Foreword Sichuan Lutianhua (Group) Co., Ltd. Power Plant was designed by our institute in the early 1960s and is equipped with 4 sets of 74MW natural gas generators. After the high cost of power generation, two 25MW generators were dismantled in 2000. Two 12MW generators are now connected to the main 6kVI busbar of the power plant. Usually, a single operation with a small amount of active power is used as a company-wide reactive power compensation and it is also important for the company. Load security power supply.
The power plant currently has two three-volume load-carrying main transformers (capacity 40 MVA, ratio 110/35/6 kV). The high-voltage side is connected to the 110kV power grid in Southern Sichuan via a 110kV line via an expansion unit; the 35kV side is a single busbar connection, and the one-time outlet is used for the subordinate plant load; the 6kV side is divided into a main 6kV (phase 0, I, and II) and factory With 6kV (5,6,7 segments) in two parts, the main 6kV uses double bus single segmented wiring to supply power to the 14 6kV substations of the company's sub-factories.
At present, 90% of the company's electrical energy is supplied by the power grid. The power plant has actually been considered as a terminal substation of the 110kV power grid in Southern Sichuan, and the power plant's 110/35/6kV power distribution unit has become Lutianhua's power supply center and control center.
Lutianhua Power Plant has been operating for nearly 40 years. Its outdated equipment and outdated control methods are not commensurate with its position in Lutianhua's production and life. Therefore, Lutianhua proposes to use limited funds for Lutianhua. Some key electrical primary equipment and electrical secondary control systems of the power plant undergo a full-scale technological transformation.
1 In the current period, the 1.1110kV primary transformation of electrical equipment was due to the fact that the Lutianhua Power Plant had only one 110kV line connected to the grid, which did not fundamentally guarantee the reliability of power supply. In this phase of renovation, a new 110kV line will be added and the bridge will be supplied with the original 110kV line. At the same time, in order to meet the needs of the current five-phase transformation prevention, the original 110kV multi-oil circuit breaker will be replaced with an SF6 circuit breaker. The original manual operation The isolating switch is replaced with an electrically operated disconnecting switch and a grounding switch. The 110 kV current transformer and voltage transformer will also be replaced together.
1.235kV part of the transformation will be the construction of a new 35kV switchgear, the use of vacuum switchgear to replace the existing switch, while leaving the single busbar transformation into a single busbar section and increase the possibility of a 35kV outlet.
1.3 The main 6kV part will not be changed for the main 6kV electrical main equipment in this period, but in order to meet the needs of the electrical five prevention reforms, the original auxiliary contacts for circuit breakers will be replaced (control, measurement and relay protection equipment will also be replaced due to the old and new. The operating handle and auxiliary contacts of the original hand-operated disconnecting switch and earthing switch will be replaced. At the same time, mechanical connecting rods and electromagnetic locks for electrical five-prevention will be added.
Before the main 6kV power distribution interval, the net will be increased by five electromagnetic locks.
In order to solve the main 6kV bus repair and ground electrical fault prevention, the current phase of the transformation will be in the main 6kV each voltage transformer interval plus busbar repair grounding knife and electromagnetic lock, through the voltage transformer before the gap between the gate and the repair of the grounding knife double electrical connection Lock to achieve the mother repair ground electrical error prevention.
The main 6kV will add grounding and arc suppression coils and capacitive reactive power compensation devices.
1.4 The factory power supply 6kV part of the plant power supply 6kV part is intended to be changed from the original three busbars to two sections, the original switchgear is replaced by a car-type switchgear, and each section will be provided with a fixed busbar overhaul grounding switchgear.
1.5 The 380V power supply for the 380V part of the plant's power supply is intended to be changed from the original three-stage bus to the two sections, and the original switchgear will be replaced. In the current period, the main 6kV new grounding transformer will be modified and the 6kV new grounding compensation device will also serve as the grounding change for the factory power supply.
1.6 Main transformers and neighboring devices #1 and #2 main transformers were upgraded to SFSZ-40000/110 three-volume on-load tap-changer in 1995 and 2000 respectively, and #2 main transformer neutral grounding switch and 35kV side. The isolating switch has also been replaced (in this period, the manual operating mechanism needs to be replaced with an electric operating mechanism), and the #1 main transformer neutral grounding switch and 35kV side isolating switch will be replaced in this period.
2 Current Secondary Electrical Equipment Transformation 2.1 The Necessity of Electrical Secondary Equipment Retrofitting The secondary system equipment of Lutianhua Power Plant is the product of the 1950s and 1960s, after more than 30 years of operation, it has now exceeded the normal service life. With the addition of various kinds of pollution such as chemical corrosive gas and moisture environment, the overall insulation of the secondary equipment is weak, the performance is declining, and the electrical accident rate is gradually increased. According to statistics, all types of electrical accidents occurred from July 1990 to January 1997 as follows:
(1) The failure caused by the aging of the control switch and terminal is 30 times, which accounts for 34.1% of the total;
(2) 21 failures caused by the drop in the insulation of the control cable core wire, accounting for 23.9% of the total number of cases;
(3) 27 accidents caused by relay protection and internal faults of automatic devices, accounting for 30.7% of the total failures;
(4) Others (including misuse) 10 times, accounting for 11.4%;
The above accident statistics show that the secondary system caused an accident accounted for 88.796 of the total number of statistics, and most of the other 10 were caused by misoperation due to the lack of good anti-mistake hardware measures. This clearly shows that the secondary system is crucial for safe and reliable power supply.
At present, there are many hidden dangers and defects in power plants, such as:
(1) The aging of the DC equipment, the battery life exceeds the service life;
(2) The control is entirely based on manual operation. The amount of surveillance and inspection is large and wide. The records are cumbersome and arbitrary, and the real-time performance is poor.
(3) Insulation aging of secondary equipment and cable conductors, and the probability of false tripping increases;
(4) Some relay protection configurations are already in compliance with current regulations, and many relay protections do not meet the requirements of reliability, selectivity, and sensitivity;
(5) The voltage system at all levels has no complete standby power supply for self-investment;
(6) The automatic quasi-synchronous device is scrapped, and the existing manual quasi-synchronizing device can not meet the requirements of the same frequency and the same time in the same period;
(7) The generator excitation system is not adapted to the requirements of the deep reactive power compensation required by the generator;
(8) Disturbance recording system is scrapped;
(9) The low-frequency de-rating and low-frequency de-sequencing technology is backward;
(10) The lack of a complete anti-misoperation locking system for accidents occurs from time to time; misoperation accidents occur from time to time;
In summary, it is necessary to carry out a thorough technological transformation of the secondary system.
2.2 The scope of the transformation of electric secondary equipment in this period According to the contract entrusted by Lutianhua (Group) Co., Ltd., the scope of electric secondary system transformation in this period is as follows:
(1) DC batteries and DC equipment replacement, DC cable replacement;
(2) Generator excitation system replacement;
(3) 110kV line protection replacement;
(4) Generator protection replacement;
(5) The control, measurement and signal of all electrical secondary equipment are changed from the normal mode to the computer monitoring mode and the interface with the lower substation and the superior dispatching center and the company computer management system is considered;
(6) Replace automatic synchronizing devices and manual synchronizing devices;
(7) Adding a complete standby power source for self-investment;
(8) 35kV distribution device control, measurement, signal and relay protection equipments are replaced with the switchgear;
(9) The main 6kV switch reserved for this modification is controlled locally. Measurement, signal and relay protection equipment replacement;
(10) 6kV switch cabinet design for the factory;
(11) Factory use 380V into each and sectional switch cabinet design;
(12) Secondary line design of the main 6kV grounding compensation device;
(13) Coordination and cooperation of generator AVR, main transformer on-load voltage regulation and non-commutation capacitor switching;
(14) replacement of low-frequency frequency-reduced splitting devices;
(15) Replacement of fault recording device;
(16) Adding complete telecontrol communications;
(17) Comprehensive improvement of five-level electrical voltage protection devices at all levels;
(18) The secondary line design for the electrical equipment to be replaced during the transformation;
2.3 The overall objective of the current secondary electrical equipment reform in accordance with the company's requirements, the purpose of this transformation is to improve the operational reliability and automation level, reduce the labor intensity of the operating personnel, so that Lutianhua Power Plant truly become the company's modern energy management center. After negotiation, the overall goals for the transformation of secondary electrical equipment in this period are as follows:
(1) Through technological transformation, realize the secondary functions of the power plant's electrical system: "integration of functions, structure, computerization, operation monitoring, screen display, and intelligent operation management";
(2) The control operation is mainly based on intelligent control and supplemented by manual control, making the power plant a monitoring station, measurement, signal, protection, automatic device, etc., adopting an integrated automation technology.
(3) Form a company-wide power plant monitoring and control center. Collect all required information (including part of thermal worker information) within the power plant, and receive substation information at the same time to realize monitoring and remote control in the entire company's electrical system;
(4) Utilize the large-scale database of power plant microcomputer monitoring system to interface with the company's total reconciliation company's computer management information system to provide on-site real-time and historical data, accept company scheduling orders, and be able to interact with higher-level grid dispatch systems to achieve remote communication, telemetry, Remote control, remote adjustment.
2.4 The current plan for the second-phase transformation of electrical equipment Before and during the implementation of the transformation design, we exchanged opinions with the relevant leaders and technical personnel of the company on many occasions regarding the overall objective of the transformation and specific plans. In addition to clearly stating that the entire project should be technically reliable, advanced, and mature, the company repeatedly stressed that the current phase of the transformation should not cause the entire company to suspend power for a long time to affect chemical production. That is, all technical solutions should fully consider step-by-step implementation and The power outage time required for each step of the implementation should be as short as possible operability.
After carefully studying these requirements and repeatedly selecting suitable equipment, we propose the following concrete reform of the electrical secondary system in this period as follows:
2.4.1 The DC system replaces the existing battery with a maintenance-free valve-regulated lead-acid battery. The battery is placed horizontally, integrated components are rack-mounted and connected by factory-assembled batteries and all mounting accessories. The floor space is small, plus the acid is filled before the factory and all performance tests are completed, and they are put into use soon after they arrive on site.
Replace the existing charging device with a new high-frequency switching power supply.
By increasing the battery capacity and setting up the silicon pressure-relief device scheme to meet the main 6kV high current closing (244A) impact load requirements, in order to cancel the original end battery and end battery regulator.
Replace the DC screen with a new DC screen equipped with a complete DC system voltage and insulation abnormality monitoring device (which can measure a specific grounding feeder) and a battery performance abnormality monitoring device.
DC charging device and monitoring device can communicate with computer monitoring system.
The storage battery is placed in the main control room of the main control building Om. The new DC device screen is arranged in the control room.
2.4.2 UPS
In this period, the transformation will increase the microcomputer monitoring system, microprocessor-based generator protection, microcomputer-based line protection, microcomputer-based generator excitation system, and microcomputer-based fault recording screens. Equipment that requires the use of AC uninterruptible switching power supply (abbreviated as UPS) The next step thermal power plant transformation may also increase the microcomputer-based smart devices also need to use UPS power supply, so the current phase of the transformation plan to add UPS systems, UPS and computer monitoring system communication interface.
The UPS does not have a battery and the UPS equipment is located in the main control room.
2.4.3 Generator Excitation generator excitation is now compound excitation, equipped with ZLQ-70TH AC exciter and KFD-3 voltage regulator, and the whole plant is also equipped with a standby DC exciter.
In this period, the transformation will be replaced with a self-excitation static excitation system, canceling the original AC exciter and standby DC exciter.
The self-excitation static excitation system obtains the excitation power from the generator-side excitation transformer, and uses a dual-channel digital AVR to control the thyristor rectifier device, which has the characteristics of fast response and good demagnetization and can be used to communicate with the microcomputer monitoring system. The voltage and reactive power control with the entire power plant can be well coordinated to meet the required generator depth reactive power compensation adjustment requirements. In order to shorten the contact cables and reduce the amount of civil engineering work required for new equipment layout, it is proposed that the screens of the self excitation and excitation system of the static excitation system be arranged on the generator operation layer.
2.4.4 Relay Protection 2.4.4.1 Main Equipment Protection (1) Main Transformer Protection The main transformer protection and transformation of the power plant was implemented in 2000. It has been converted to a NARI LFP-941A microcomputer and put into operation. The transformation of this period is mainly to consider the interface with the transformation of the equipment.
(2) The 110kV protection power plant ordered a set of Nanrui LFP-941A microprocessor protection in 2000 (but has not yet implemented the transformation). In the current period, the transformation is to order a set of same-type protection and implement the relevant secondary transformation. At the same time, consider the interface with the current modification equipment. .
(3) Generator protection Generator protection is configured according to (Specifications for Relay Protection and Automatic Device Design of Electrical Installations (GB50062-92). The selection of protection type of generators is to adopt complete protection of microcomputer-type generators, protection energy and microcomputer monitoring system. Interfaces, protection outlets are hardwired directly to the relevant circuit breakers.
The above main equipment protection screens are all arranged in the main control room.
2.4.4.23SkV switchgear protection 35kV switchgear The new switchgear, 35kV relay protection and secondary equipment are supplied with the new switchgear. All kinds of switch cabinets use integrated automation devices that integrate relay protection, real-time measurement, control anti-jump, low-cycle load shedding and reclosing and other functions and can communicate with the microcomputer monitoring system. They have the following protection functions:
(1) 35kV line protection compound voltage latching current quick-break compound voltage latching time limit over-current zero-sequence voltage block zero-sequence over-current three-phase one-time reclosing after reclosing acceleration fast bus protection (2) 35kV line protection 35kV line switch at the same time It is also the main breaker of 35kV side breaker. The protection has been integrated into the main transformer protection. However, considering the monitoring integration and the 35kV bus protection needs, the same integrated automation device as the 35kV line is still used, except that only the fast busbar protection is retained in the protection function ( The rest is closed).
(3) 35kV bus protection uses 35kV bus protection and 35kV bus line 35kV bus protection. The 35kV bus protection is used for 35kV bus protection. 35kV line protection will block the 35kV standby power supply from the vote.
2.4.4.2 Main 6kV switchgear protection The main 6kV switchgear does not change the switch, the newly-changed relay protection and the power control box for the secondary equipment with each new interval (power control box is arranged at the original terminal Box position) is delivered together. All kinds of main 6kV switch protection adopts integrated automation devices that integrate relay protection, real-time measurement, control anti-jump, low-cycle load reduction and other functions and can communicate with the microcomputer monitoring system. They have the following protection functions:
(1) Main 6kV distribution station feeder protection compound voltage latching current quick-break compound voltage latching time limit over-current zero-sequence voltage blocking zero-sequence over-current fast bus protection 6kV feeder circuit breaker breaking capacity is not enough, composite voltage blocking current quick-break protection should be separate The outlet locks the feeder switch tripping and starts the main 6kV line breaker trip.
(2) The main 6kV line protection 6kV line switch is also the main transformer 6kV side circuit breaker, and the protection has been integrated into the main transformer protection. However, considering the monitoring integration and the need for 6kV bus protection, the 6kV distribution line feeder is still used. The same comprehensive automation device, except that only the fast bus protection is retained in the protection function (the rest is closed).
(3) The main 6kV segment protection adopts the same integrated automation device as the 6kV distribution station feeder, except that only the composite voltage lockout zone time-over-current and the fast bus protection (remaining shutdown) are retained in the protection function.
(4) Main 6kV earthing change protection This period reformation uses the original 6kV original air space (original switch) to add a grounding transformer for the 6kV system grounding compensation arc suppression coil. Consider the use of a microcomputer type transformer integrated automatic device with the following protection :
High-voltage side current quick-break high-voltage side with time-limit current High-voltage side unbalance high-pressure side zero-sequence current (only signal)
Main body protection rapid mother protection Because the breaking capacity of the 6kV circuit breaker is not enough, the composite voltage blocking current quick-break protection should separate the outlet and lock the feeder switch tripping and start the main 6kV line switch tripping.
(5) Main 6kV static compensation capacitor protection In this period, the transformation uses the main 6kY original empty interval (new breaker change) to add a parallel static compensation capacitor bank. Considering the use of a microcomputer type capacitor integrated automation device, it has the following protection:
Current Speed ​​Breakage Time Limit Over Current Unbalanced Current Unbalanced Voltage Over Voltage Under Voltage Zero Sequence Overcurrent (6) Main 6kV Mains Power Supply Feeder Protection Main 6kV Mains Power Feeder Installation Same as main 6kV Mains Feeder Feed (Closed Low-week reduction).
Because the 6kV feeder switch has insufficient breaking capacity, the composite voltage blocking current quick-break protection should be independent and the output should be closed and the feeder switch should be tripped while the main 6kV line switch should be tripped.
(7) The main 6kV bus uses the fast line protection function of the 6kV feeder, incoming line, and subsection integrated automation devices to constitute a 6kV busbar protection. No special 6kV bus protection is provided.
The 6kV bus protection action will latch the 6kV standby power supply from the input.
2.4.4.3 Factory power distribution equipment The protection plant uses 6kV and 380V power distribution devices to switch the new switches and related protections according to the “Technical Regulations for Power Design of Power Plantsâ€, and the protection device is consistent with the main 6kV.
2.4.5 Microcomputer monitoring system This phase of the transformation will use a computer monitoring system to replace the conventional control, signal and measurement systems.
2.4.5.1 Basic configuration of the microcomputer monitoring system The microcomputer monitoring system considers the use of a fully distributed open system architecture. The monitoring system host/operator station uses dual redundant configuration hot standby, and the communication trunk uses 100M dual Ethernet.
The microcomputer monitoring system consists of a bay layer and a station control layer. The bay layer and the station control layer are connected via a communication network and a communication interface.
The separation layer is composed of main equipment monitoring unit (such as generator, main transformer, 110kV line, etc.) and main equipment microcomputer protection unit equipped with 35kV and 6kV on-site comprehensive automation equipment units. The main equipment monitoring unit is centrally grouped and placed in the main control room.
The station control layer includes host/operator workstations, relay/engineer workstations, computer error prevention workstations, GPS time-of-flight systems, telecontrol communication workstations, and printers. The station-level equipment is located in the control room.
2.4.5.2 Main functions of the microcomputer monitoring system 2.4.5.2.1 All control, protection, measurement, alarm signals and telecontrol information of the bay layer are implemented in each bay unit and collected and processed. The data number is transmitted to the station control layer via the communication network.
2.4.5.2 Station Control Stations The main equipment functions are as follows:
(1) The host and operator workstation host is responsible for data and network management, and the operator workstation is responsible for the entire station operation.
The host adopts the dual-machine configuration, and the host-hot standby mode works. When the host fails, the hot standby machine self-upgrades to the host.
The operator workstation sets up two sets of computer monitor keyboard and mouse/21 color display man-machine interface, which can carry out operation monitoring and operation control on the electrical equipment of the power plant at the operator workstation (including all circuit breakers and breakers; generator active power regulation; generator AVR control, main transformer on-load tap changer adjustment, 6kV reactive power compensation switching, and overall power plant compensation for reactive power compensation; standby power supply for slow self-injection; low-cycle load shedding and low-frequency decoupling, etc.), electrical measurement Calculation, real-time screen report recording and file generation, modification and printing, acousto-optic signal alarm, real-time database storage, history database modification, system clock management, etc.
(2) Relay protection/engineering station relay protection/engineering station completes the function configuration and maintenance of each set of microcomputer protection, carries out relay protection program modification and development, relay protection database parameters and parameter structure modification, and relay protection database reference data And reference data structure modification, relay protection fixed value query and modification and remote diagnosis of relay protection.
(3) Microcomputer anti-mistake workstation Anti-mistake workstation is an independent microcomputer anti-locking microcomputer device, including a computer, keyboard, mouse, 21 "color display, computer keys, code locks, special printers.
The microcomputer anti-mistake workstation has various device operation blocking logics and obtains comprehensive on-site information through the communication interface with the host/operating station. It can realize remote electrical five-operation blocking and can perform various operation lock simulation training and perform operation ticket rehearsal.
The operation ticket is output by a dedicated workstation printer.
(4) Telecontrol workstations The microcomputer monitoring system sets up two sets of remote communication workstations to be responsible for communication interfaces with remote dispatching and lower level power distribution stations and company dispatch management centers, and to send information to the head office dispatch center to receive The remote control and remote adjustment commands of the head office's dispatch center were adjusted to realize automatic dispatching.
Remote communication workstations are dual redundant and standby.
(5) Satellite clock receiving system GPS
The standard clock information is received by the satellite clock receiving system GPS and expanded by the GPS clock pulse extender for the clock synchronization of numerous microcomputer relay protection and control of the station layer.
2.4.6 Secondary wiring and automatic device 2.4.6.1 Control mode In the current phase of the renovation, the conventional control screen will be cancelled and secondary control based on computer control will be supplemented by local control.
The first level is controlled at the main control room host/operator station. Under normal circumstances, all control, monitoring, measurement and alarm functions are completed here, through the screen display device operating conditions, through the key mouse-man-machine session to operate.
The second level of control is accomplished by a manual control switch mounted on each bay level monitoring unit. This method is a backup method used to operate the circuit breaker in the case of the microcomputer supervision system and the step-by-step implementation of the current phase of the modification.
The two-stage control is switched by the switch installed in the monitoring unit of each bay level. The second-level manual control is the compulsory mode. Once it is implemented, the closing command of the first-level control is no longer valid.
The generator active power regulation is implemented through the microcomputer control system hard wiring control turbine main valve servo motor implementation.
Since the turbine control is not synchronized in the current period, it still retains the generator-steam turbine command signal, that is, the microcomputer monitoring system converts the regulation command to the empty contact point and connects the cable to the turbine control panel to command the signal light. The turbine control panel returns the signal via the cable. When connected to the computer monitor, the system is converted into a parallel screen display. The on-screen generator emergency stop button is directly connected to the generator circuit breaker opening circuit via the cable.
Generator voltage and reactive power regulation are implemented by microcomputer monitoring system and generator microcomputer AVR communication interface.
2.4.6.2 Monitoring mode Since the microcomputer monitoring system has the functions of position status screen display, sound and light alarm, accident record analysis, trend analysis and automatic printing, a large number of electrical displays, switch position status and alarms are of high resolution. CRT screen flash, text prompts and different audio or speech alarm device replacement, the current transformation of the main control room will cancel the original regular traffic light position signal, flash signal, the central signal system and light word row signal.
Because the microcomputer monitoring system has the functions of analog acquisition and processing (including all electrical quantities and some non-electrical quantities, such as transformer temperature, main steam pressure, flow, temperature, natural gas pressure, etc.), it can monitor all kinds of electrical on-line on the screen in real time. Quantity and non-electrical quantities can be printed and tabulated at regular intervals and beyond. Digital units are also displayed in the monitoring units at each bay level. Various electrical parameters can be observed for each circuit. In this period, the original meter will be cancelled.
In order to ensure the accuracy of measurement and evaluation, a functional reactive power pulse power meter is set up separately at 110kV line, 35kV line and 6kV distribution line feeder, and the pulse information is sent to the microcomputer monitoring system for monitoring and recording.
2.4.6.3 In the same period, the generator breaker, the main 6kV incoming line and the segmented circuit breaker are automatically quasi-synchronized. The manual quasi-synchronization period includes the automatic quasi-synchronization point and the circuit breaker that needs to be switched first and then disconnected.
In the current period, the new microcomputer-based automatic quasi-synchronization and manual quasi-synchronization devices and the communication interface with the microcomputer monitoring system were newly established.
In the automatic quasi-synchronization period, the servo motor of the main valve of the turbine is controlled by hard wiring and the voltage of the generator AVR is adjusted by the hard wiring.
The manual quasi-synchronization period can be controlled by the microcomputer monitoring system to control the turbine main valve servo motor adjustment frequency and control the generator AVR regulation voltage as a backup method for automatic quasi-synchronization. It can also be set to capture the difference frequency or frequency synchronization of non-automatic quasi-contemporaneous points at the same time. brake.
The process of the same period can be displayed through the computer monitor screen, and the original conventional system is cancelled during the same period.
2.4.6.4 Electrical Five Prevention This phase of the transformation will be achieved by the computer error prevention workstation and the transformation of the site of electrical anti-misoperation locking two kinds of voltage levels of the circuit breaker, disconnector, grounding switch operation and distribution Electrical devices are divided into five doors and other electrical gates to prevent blocking.
2.4.6.5 Standby power supply Self-powered voltage levels The standby power supply will be switched slowly by the microcomputer monitoring system with low voltage criteria.
Standby power supply from the investment level from high to low to achieve the order of self-investment, if the high voltage level backup power supply from the successful investment will be locked low voltage standby power supply from the vote.
The main transformer protection action will block the 110kV standby power supply from the input; the 35kV bus protection action will block the 35kV standby power supply from the input; the 6kV bus protection action will latch the 6kV standby supply from the input.
2.4.6.6 Low-cycle load shedding and low-frequency decoupling The low-cycle load-shedding point is the main 6kV substation feeder line. The low-cycle load shedding considers two-stage frequency and time. The first stage is implemented by a 6kV feeder integrated automation device, and the second stage is implemented by a microcomputer monitoring system.
The low-frequency solution point is mainly 110/3576kV three sides optional. The low frequency de-solving takes into account two levels of frequency and time and is implemented by a microcomputer monitoring system.
The frequency and time for low-cycle load shedding and low-frequency decoupling can be set as needed. After the low-frequency decoupling, the generators bring important load to the company.
2.4.6.7 Disturbance Recording In order to independently and accurately analyze electrical faults, it is proposed to set up an important analogue quantity and switch quantity recording wave for 110kV line, main transformer, generator and each level voltage bus of the microcomputer type fault recording screen.
2.4.6.86kV Grounding Compensation 6kV Grounding Compensation Grounding Transformation and Arc Suppression Coil The self-contained arc-suppression coil tap adjuster can automatically adjust according to the compensation requirements. At the same time, the microcomputer monitoring system can also perform remote adjustment control of the tap.
2.4.6.9 Reactive Power Compensation In the current period, the main renovating main 6kV will be added with a new reactive compensation capacitor bank. The microcomputer monitoring system will base the generator AVR, on-load tap changer tap and reactive power compensation capacitor bank according to the compensation requirements. Circuit breaker switching implements remote joint regulation control.
2.4.7 Implementation steps Based on the above technical scenarios and the careful organization of the company in the future, we believe it is very hopeful to meet the company's requirements that “the step-by-step implementation and the time required for blackouts for each step of implementation should be as short as possibleâ€. The steps suggested are as follows:
(1) The DC system shall be equipped with new equipment first, and the DC feeder cables shall be replaced one by one. Finally, the existing DC system equipment and cables shall be removed;
(2) The UPS is newly installed and can be carried out at any time as required;
(3) The generator will only operate one unit at a time, and the excitation system and relay protection replacement can be carried out in separate units;
(4) The second transformation of 110kV can be carried out with a single device replacement;
(5) The 35kV distribution equipment shall be built before demolition, and the secondary equipment shall be implemented together with the new switch cabinet;
(6) The main 6kV power distribution device can be repaired and shut down at intervals, and the auxiliary auxiliary switch, on-site five-defense modification and secondary equipment modification can be carried out together. Secondary equipment modification Since the new local control box can be quickly put into use local control, and then choose the machine to carry out joint adjustment with the computer monitoring system communication interface will not cause long-term power outage;
(7) The transformation of the main control room can be based on the design plan to install a new screen at the screen location, and then gradually remove the cancel screen to install the remaining new screen gradually, and finally remove all intended to cancel the screen after the main control room room separation and appropriate decoration;
(8) The main control room cable transition, because the use of computer monitoring system to enter the main control cable is greatly reduced, new or new cable can be considered appropriate to leave a certain length along the edge of the cable sandwich first laying to the new screen of the current period, pending demolition After the cable, press the planning channel in place.
Concluding Remarks We believe that the above solutions are technically advanced and mature, and site implementation is also feasible. Plus, the preliminary estimation of the secondary part of the electrical transformation of the current period will require about RMB 4 million, which will be more reliable for the Tiantianhua Power Plant. The power supply has greatly improved the company's chemical safety production reliability. It should be said that it is a very effective and worthwhile investment in technological transformation.
The power plant currently has two three-volume load-carrying main transformers (capacity 40 MVA, ratio 110/35/6 kV). The high-voltage side is connected to the 110kV power grid in Southern Sichuan via a 110kV line via an expansion unit; the 35kV side is a single busbar connection, and the one-time outlet is used for the subordinate plant load; the 6kV side is divided into a main 6kV (phase 0, I, and II) and factory With 6kV (5,6,7 segments) in two parts, the main 6kV uses double bus single segmented wiring to supply power to the 14 6kV substations of the company's sub-factories.
At present, 90% of the company's electrical energy is supplied by the power grid. The power plant has actually been considered as a terminal substation of the 110kV power grid in Southern Sichuan, and the power plant's 110/35/6kV power distribution unit has become Lutianhua's power supply center and control center.
Lutianhua Power Plant has been operating for nearly 40 years. Its outdated equipment and outdated control methods are not commensurate with its position in Lutianhua's production and life. Therefore, Lutianhua proposes to use limited funds for Lutianhua. Some key electrical primary equipment and electrical secondary control systems of the power plant undergo a full-scale technological transformation.
1 In the current period, the 1.1110kV primary transformation of electrical equipment was due to the fact that the Lutianhua Power Plant had only one 110kV line connected to the grid, which did not fundamentally guarantee the reliability of power supply. In this phase of renovation, a new 110kV line will be added and the bridge will be supplied with the original 110kV line. At the same time, in order to meet the needs of the current five-phase transformation prevention, the original 110kV multi-oil circuit breaker will be replaced with an SF6 circuit breaker. The original manual operation The isolating switch is replaced with an electrically operated disconnecting switch and a grounding switch. The 110 kV current transformer and voltage transformer will also be replaced together.
1.235kV part of the transformation will be the construction of a new 35kV switchgear, the use of vacuum switchgear to replace the existing switch, while leaving the single busbar transformation into a single busbar section and increase the possibility of a 35kV outlet.
1.3 The main 6kV part will not be changed for the main 6kV electrical main equipment in this period, but in order to meet the needs of the electrical five prevention reforms, the original auxiliary contacts for circuit breakers will be replaced (control, measurement and relay protection equipment will also be replaced due to the old and new. The operating handle and auxiliary contacts of the original hand-operated disconnecting switch and earthing switch will be replaced. At the same time, mechanical connecting rods and electromagnetic locks for electrical five-prevention will be added.
Before the main 6kV power distribution interval, the net will be increased by five electromagnetic locks.
In order to solve the main 6kV bus repair and ground electrical fault prevention, the current phase of the transformation will be in the main 6kV each voltage transformer interval plus busbar repair grounding knife and electromagnetic lock, through the voltage transformer before the gap between the gate and the repair of the grounding knife double electrical connection Lock to achieve the mother repair ground electrical error prevention.
The main 6kV will add grounding and arc suppression coils and capacitive reactive power compensation devices.
1.4 The factory power supply 6kV part of the plant power supply 6kV part is intended to be changed from the original three busbars to two sections, the original switchgear is replaced by a car-type switchgear, and each section will be provided with a fixed busbar overhaul grounding switchgear.
1.5 The 380V power supply for the 380V part of the plant's power supply is intended to be changed from the original three-stage bus to the two sections, and the original switchgear will be replaced. In the current period, the main 6kV new grounding transformer will be modified and the 6kV new grounding compensation device will also serve as the grounding change for the factory power supply.
1.6 Main transformers and neighboring devices #1 and #2 main transformers were upgraded to SFSZ-40000/110 three-volume on-load tap-changer in 1995 and 2000 respectively, and #2 main transformer neutral grounding switch and 35kV side. The isolating switch has also been replaced (in this period, the manual operating mechanism needs to be replaced with an electric operating mechanism), and the #1 main transformer neutral grounding switch and 35kV side isolating switch will be replaced in this period.
2 Current Secondary Electrical Equipment Transformation 2.1 The Necessity of Electrical Secondary Equipment Retrofitting The secondary system equipment of Lutianhua Power Plant is the product of the 1950s and 1960s, after more than 30 years of operation, it has now exceeded the normal service life. With the addition of various kinds of pollution such as chemical corrosive gas and moisture environment, the overall insulation of the secondary equipment is weak, the performance is declining, and the electrical accident rate is gradually increased. According to statistics, all types of electrical accidents occurred from July 1990 to January 1997 as follows:
(1) The failure caused by the aging of the control switch and terminal is 30 times, which accounts for 34.1% of the total;
(2) 21 failures caused by the drop in the insulation of the control cable core wire, accounting for 23.9% of the total number of cases;
(3) 27 accidents caused by relay protection and internal faults of automatic devices, accounting for 30.7% of the total failures;
(4) Others (including misuse) 10 times, accounting for 11.4%;
The above accident statistics show that the secondary system caused an accident accounted for 88.796 of the total number of statistics, and most of the other 10 were caused by misoperation due to the lack of good anti-mistake hardware measures. This clearly shows that the secondary system is crucial for safe and reliable power supply.
At present, there are many hidden dangers and defects in power plants, such as:
(1) The aging of the DC equipment, the battery life exceeds the service life;
(2) The control is entirely based on manual operation. The amount of surveillance and inspection is large and wide. The records are cumbersome and arbitrary, and the real-time performance is poor.
(3) Insulation aging of secondary equipment and cable conductors, and the probability of false tripping increases;
(4) Some relay protection configurations are already in compliance with current regulations, and many relay protections do not meet the requirements of reliability, selectivity, and sensitivity;
(5) The voltage system at all levels has no complete standby power supply for self-investment;
(6) The automatic quasi-synchronous device is scrapped, and the existing manual quasi-synchronizing device can not meet the requirements of the same frequency and the same time in the same period;
(7) The generator excitation system is not adapted to the requirements of the deep reactive power compensation required by the generator;
(8) Disturbance recording system is scrapped;
(9) The low-frequency de-rating and low-frequency de-sequencing technology is backward;
(10) The lack of a complete anti-misoperation locking system for accidents occurs from time to time; misoperation accidents occur from time to time;
In summary, it is necessary to carry out a thorough technological transformation of the secondary system.
2.2 The scope of the transformation of electric secondary equipment in this period According to the contract entrusted by Lutianhua (Group) Co., Ltd., the scope of electric secondary system transformation in this period is as follows:
(1) DC batteries and DC equipment replacement, DC cable replacement;
(2) Generator excitation system replacement;
(3) 110kV line protection replacement;
(4) Generator protection replacement;
(5) The control, measurement and signal of all electrical secondary equipment are changed from the normal mode to the computer monitoring mode and the interface with the lower substation and the superior dispatching center and the company computer management system is considered;
(6) Replace automatic synchronizing devices and manual synchronizing devices;
(7) Adding a complete standby power source for self-investment;
(8) 35kV distribution device control, measurement, signal and relay protection equipments are replaced with the switchgear;
(9) The main 6kV switch reserved for this modification is controlled locally. Measurement, signal and relay protection equipment replacement;
(10) 6kV switch cabinet design for the factory;
(11) Factory use 380V into each and sectional switch cabinet design;
(12) Secondary line design of the main 6kV grounding compensation device;
(13) Coordination and cooperation of generator AVR, main transformer on-load voltage regulation and non-commutation capacitor switching;
(14) replacement of low-frequency frequency-reduced splitting devices;
(15) Replacement of fault recording device;
(16) Adding complete telecontrol communications;
(17) Comprehensive improvement of five-level electrical voltage protection devices at all levels;
(18) The secondary line design for the electrical equipment to be replaced during the transformation;
2.3 The overall objective of the current secondary electrical equipment reform in accordance with the company's requirements, the purpose of this transformation is to improve the operational reliability and automation level, reduce the labor intensity of the operating personnel, so that Lutianhua Power Plant truly become the company's modern energy management center. After negotiation, the overall goals for the transformation of secondary electrical equipment in this period are as follows:
(1) Through technological transformation, realize the secondary functions of the power plant's electrical system: "integration of functions, structure, computerization, operation monitoring, screen display, and intelligent operation management";
(2) The control operation is mainly based on intelligent control and supplemented by manual control, making the power plant a monitoring station, measurement, signal, protection, automatic device, etc., adopting an integrated automation technology.
(3) Form a company-wide power plant monitoring and control center. Collect all required information (including part of thermal worker information) within the power plant, and receive substation information at the same time to realize monitoring and remote control in the entire company's electrical system;
(4) Utilize the large-scale database of power plant microcomputer monitoring system to interface with the company's total reconciliation company's computer management information system to provide on-site real-time and historical data, accept company scheduling orders, and be able to interact with higher-level grid dispatch systems to achieve remote communication, telemetry, Remote control, remote adjustment.
2.4 The current plan for the second-phase transformation of electrical equipment Before and during the implementation of the transformation design, we exchanged opinions with the relevant leaders and technical personnel of the company on many occasions regarding the overall objective of the transformation and specific plans. In addition to clearly stating that the entire project should be technically reliable, advanced, and mature, the company repeatedly stressed that the current phase of the transformation should not cause the entire company to suspend power for a long time to affect chemical production. That is, all technical solutions should fully consider step-by-step implementation and The power outage time required for each step of the implementation should be as short as possible operability.
After carefully studying these requirements and repeatedly selecting suitable equipment, we propose the following concrete reform of the electrical secondary system in this period as follows:
2.4.1 The DC system replaces the existing battery with a maintenance-free valve-regulated lead-acid battery. The battery is placed horizontally, integrated components are rack-mounted and connected by factory-assembled batteries and all mounting accessories. The floor space is small, plus the acid is filled before the factory and all performance tests are completed, and they are put into use soon after they arrive on site.
Replace the existing charging device with a new high-frequency switching power supply.
By increasing the battery capacity and setting up the silicon pressure-relief device scheme to meet the main 6kV high current closing (244A) impact load requirements, in order to cancel the original end battery and end battery regulator.
Replace the DC screen with a new DC screen equipped with a complete DC system voltage and insulation abnormality monitoring device (which can measure a specific grounding feeder) and a battery performance abnormality monitoring device.
DC charging device and monitoring device can communicate with computer monitoring system.
The storage battery is placed in the main control room of the main control building Om. The new DC device screen is arranged in the control room.
2.4.2 UPS
In this period, the transformation will increase the microcomputer monitoring system, microprocessor-based generator protection, microcomputer-based line protection, microcomputer-based generator excitation system, and microcomputer-based fault recording screens. Equipment that requires the use of AC uninterruptible switching power supply (abbreviated as UPS) The next step thermal power plant transformation may also increase the microcomputer-based smart devices also need to use UPS power supply, so the current phase of the transformation plan to add UPS systems, UPS and computer monitoring system communication interface.
The UPS does not have a battery and the UPS equipment is located in the main control room.
2.4.3 Generator Excitation generator excitation is now compound excitation, equipped with ZLQ-70TH AC exciter and KFD-3 voltage regulator, and the whole plant is also equipped with a standby DC exciter.
In this period, the transformation will be replaced with a self-excitation static excitation system, canceling the original AC exciter and standby DC exciter.
The self-excitation static excitation system obtains the excitation power from the generator-side excitation transformer, and uses a dual-channel digital AVR to control the thyristor rectifier device, which has the characteristics of fast response and good demagnetization and can be used to communicate with the microcomputer monitoring system. The voltage and reactive power control with the entire power plant can be well coordinated to meet the required generator depth reactive power compensation adjustment requirements. In order to shorten the contact cables and reduce the amount of civil engineering work required for new equipment layout, it is proposed that the screens of the self excitation and excitation system of the static excitation system be arranged on the generator operation layer.
2.4.4 Relay Protection 2.4.4.1 Main Equipment Protection (1) Main Transformer Protection The main transformer protection and transformation of the power plant was implemented in 2000. It has been converted to a NARI LFP-941A microcomputer and put into operation. The transformation of this period is mainly to consider the interface with the transformation of the equipment.
(2) The 110kV protection power plant ordered a set of Nanrui LFP-941A microprocessor protection in 2000 (but has not yet implemented the transformation). In the current period, the transformation is to order a set of same-type protection and implement the relevant secondary transformation. At the same time, consider the interface with the current modification equipment. .
(3) Generator protection Generator protection is configured according to (Specifications for Relay Protection and Automatic Device Design of Electrical Installations (GB50062-92). The selection of protection type of generators is to adopt complete protection of microcomputer-type generators, protection energy and microcomputer monitoring system. Interfaces, protection outlets are hardwired directly to the relevant circuit breakers.
The above main equipment protection screens are all arranged in the main control room.
2.4.4.23SkV switchgear protection 35kV switchgear The new switchgear, 35kV relay protection and secondary equipment are supplied with the new switchgear. All kinds of switch cabinets use integrated automation devices that integrate relay protection, real-time measurement, control anti-jump, low-cycle load shedding and reclosing and other functions and can communicate with the microcomputer monitoring system. They have the following protection functions:
(1) 35kV line protection compound voltage latching current quick-break compound voltage latching time limit over-current zero-sequence voltage block zero-sequence over-current three-phase one-time reclosing after reclosing acceleration fast bus protection (2) 35kV line protection 35kV line switch at the same time It is also the main breaker of 35kV side breaker. The protection has been integrated into the main transformer protection. However, considering the monitoring integration and the 35kV bus protection needs, the same integrated automation device as the 35kV line is still used, except that only the fast busbar protection is retained in the protection function ( The rest is closed).
(3) 35kV bus protection uses 35kV bus protection and 35kV bus line 35kV bus protection. The 35kV bus protection is used for 35kV bus protection. 35kV line protection will block the 35kV standby power supply from the vote.
2.4.4.2 Main 6kV switchgear protection The main 6kV switchgear does not change the switch, the newly-changed relay protection and the power control box for the secondary equipment with each new interval (power control box is arranged at the original terminal Box position) is delivered together. All kinds of main 6kV switch protection adopts integrated automation devices that integrate relay protection, real-time measurement, control anti-jump, low-cycle load reduction and other functions and can communicate with the microcomputer monitoring system. They have the following protection functions:
(1) Main 6kV distribution station feeder protection compound voltage latching current quick-break compound voltage latching time limit over-current zero-sequence voltage blocking zero-sequence over-current fast bus protection 6kV feeder circuit breaker breaking capacity is not enough, composite voltage blocking current quick-break protection should be separate The outlet locks the feeder switch tripping and starts the main 6kV line breaker trip.
(2) The main 6kV line protection 6kV line switch is also the main transformer 6kV side circuit breaker, and the protection has been integrated into the main transformer protection. However, considering the monitoring integration and the need for 6kV bus protection, the 6kV distribution line feeder is still used. The same comprehensive automation device, except that only the fast bus protection is retained in the protection function (the rest is closed).
(3) The main 6kV segment protection adopts the same integrated automation device as the 6kV distribution station feeder, except that only the composite voltage lockout zone time-over-current and the fast bus protection (remaining shutdown) are retained in the protection function.
(4) Main 6kV earthing change protection This period reformation uses the original 6kV original air space (original switch) to add a grounding transformer for the 6kV system grounding compensation arc suppression coil. Consider the use of a microcomputer type transformer integrated automatic device with the following protection :
High-voltage side current quick-break high-voltage side with time-limit current High-voltage side unbalance high-pressure side zero-sequence current (only signal)
Main body protection rapid mother protection Because the breaking capacity of the 6kV circuit breaker is not enough, the composite voltage blocking current quick-break protection should separate the outlet and lock the feeder switch tripping and start the main 6kV line switch tripping.
(5) Main 6kV static compensation capacitor protection In this period, the transformation uses the main 6kY original empty interval (new breaker change) to add a parallel static compensation capacitor bank. Considering the use of a microcomputer type capacitor integrated automation device, it has the following protection:
Current Speed ​​Breakage Time Limit Over Current Unbalanced Current Unbalanced Voltage Over Voltage Under Voltage Zero Sequence Overcurrent (6) Main 6kV Mains Power Supply Feeder Protection Main 6kV Mains Power Feeder Installation Same as main 6kV Mains Feeder Feed (Closed Low-week reduction).
Because the 6kV feeder switch has insufficient breaking capacity, the composite voltage blocking current quick-break protection should be independent and the output should be closed and the feeder switch should be tripped while the main 6kV line switch should be tripped.
(7) The main 6kV bus uses the fast line protection function of the 6kV feeder, incoming line, and subsection integrated automation devices to constitute a 6kV busbar protection. No special 6kV bus protection is provided.
The 6kV bus protection action will latch the 6kV standby power supply from the input.
2.4.4.3 Factory power distribution equipment The protection plant uses 6kV and 380V power distribution devices to switch the new switches and related protections according to the “Technical Regulations for Power Design of Power Plantsâ€, and the protection device is consistent with the main 6kV.
2.4.5 Microcomputer monitoring system This phase of the transformation will use a computer monitoring system to replace the conventional control, signal and measurement systems.
2.4.5.1 Basic configuration of the microcomputer monitoring system The microcomputer monitoring system considers the use of a fully distributed open system architecture. The monitoring system host/operator station uses dual redundant configuration hot standby, and the communication trunk uses 100M dual Ethernet.
The microcomputer monitoring system consists of a bay layer and a station control layer. The bay layer and the station control layer are connected via a communication network and a communication interface.
The separation layer is composed of main equipment monitoring unit (such as generator, main transformer, 110kV line, etc.) and main equipment microcomputer protection unit equipped with 35kV and 6kV on-site comprehensive automation equipment units. The main equipment monitoring unit is centrally grouped and placed in the main control room.
The station control layer includes host/operator workstations, relay/engineer workstations, computer error prevention workstations, GPS time-of-flight systems, telecontrol communication workstations, and printers. The station-level equipment is located in the control room.
2.4.5.2 Main functions of the microcomputer monitoring system 2.4.5.2.1 All control, protection, measurement, alarm signals and telecontrol information of the bay layer are implemented in each bay unit and collected and processed. The data number is transmitted to the station control layer via the communication network.
2.4.5.2 Station Control Stations The main equipment functions are as follows:
(1) The host and operator workstation host is responsible for data and network management, and the operator workstation is responsible for the entire station operation.
The host adopts the dual-machine configuration, and the host-hot standby mode works. When the host fails, the hot standby machine self-upgrades to the host.
The operator workstation sets up two sets of computer monitor keyboard and mouse/21 color display man-machine interface, which can carry out operation monitoring and operation control on the electrical equipment of the power plant at the operator workstation (including all circuit breakers and breakers; generator active power regulation; generator AVR control, main transformer on-load tap changer adjustment, 6kV reactive power compensation switching, and overall power plant compensation for reactive power compensation; standby power supply for slow self-injection; low-cycle load shedding and low-frequency decoupling, etc.), electrical measurement Calculation, real-time screen report recording and file generation, modification and printing, acousto-optic signal alarm, real-time database storage, history database modification, system clock management, etc.
(2) Relay protection/engineering station relay protection/engineering station completes the function configuration and maintenance of each set of microcomputer protection, carries out relay protection program modification and development, relay protection database parameters and parameter structure modification, and relay protection database reference data And reference data structure modification, relay protection fixed value query and modification and remote diagnosis of relay protection.
(3) Microcomputer anti-mistake workstation Anti-mistake workstation is an independent microcomputer anti-locking microcomputer device, including a computer, keyboard, mouse, 21 "color display, computer keys, code locks, special printers.
The microcomputer anti-mistake workstation has various device operation blocking logics and obtains comprehensive on-site information through the communication interface with the host/operating station. It can realize remote electrical five-operation blocking and can perform various operation lock simulation training and perform operation ticket rehearsal.
The operation ticket is output by a dedicated workstation printer.
(4) Telecontrol workstations The microcomputer monitoring system sets up two sets of remote communication workstations to be responsible for communication interfaces with remote dispatching and lower level power distribution stations and company dispatch management centers, and to send information to the head office dispatch center to receive The remote control and remote adjustment commands of the head office's dispatch center were adjusted to realize automatic dispatching.
Remote communication workstations are dual redundant and standby.
(5) Satellite clock receiving system GPS
The standard clock information is received by the satellite clock receiving system GPS and expanded by the GPS clock pulse extender for the clock synchronization of numerous microcomputer relay protection and control of the station layer.
2.4.6 Secondary wiring and automatic device 2.4.6.1 Control mode In the current phase of the renovation, the conventional control screen will be cancelled and secondary control based on computer control will be supplemented by local control.
The first level is controlled at the main control room host/operator station. Under normal circumstances, all control, monitoring, measurement and alarm functions are completed here, through the screen display device operating conditions, through the key mouse-man-machine session to operate.
The second level of control is accomplished by a manual control switch mounted on each bay level monitoring unit. This method is a backup method used to operate the circuit breaker in the case of the microcomputer supervision system and the step-by-step implementation of the current phase of the modification.
The two-stage control is switched by the switch installed in the monitoring unit of each bay level. The second-level manual control is the compulsory mode. Once it is implemented, the closing command of the first-level control is no longer valid.
The generator active power regulation is implemented through the microcomputer control system hard wiring control turbine main valve servo motor implementation.
Since the turbine control is not synchronized in the current period, it still retains the generator-steam turbine command signal, that is, the microcomputer monitoring system converts the regulation command to the empty contact point and connects the cable to the turbine control panel to command the signal light. The turbine control panel returns the signal via the cable. When connected to the computer monitor, the system is converted into a parallel screen display. The on-screen generator emergency stop button is directly connected to the generator circuit breaker opening circuit via the cable.
Generator voltage and reactive power regulation are implemented by microcomputer monitoring system and generator microcomputer AVR communication interface.
2.4.6.2 Monitoring mode Since the microcomputer monitoring system has the functions of position status screen display, sound and light alarm, accident record analysis, trend analysis and automatic printing, a large number of electrical displays, switch position status and alarms are of high resolution. CRT screen flash, text prompts and different audio or speech alarm device replacement, the current transformation of the main control room will cancel the original regular traffic light position signal, flash signal, the central signal system and light word row signal.
Because the microcomputer monitoring system has the functions of analog acquisition and processing (including all electrical quantities and some non-electrical quantities, such as transformer temperature, main steam pressure, flow, temperature, natural gas pressure, etc.), it can monitor all kinds of electrical on-line on the screen in real time. Quantity and non-electrical quantities can be printed and tabulated at regular intervals and beyond. Digital units are also displayed in the monitoring units at each bay level. Various electrical parameters can be observed for each circuit. In this period, the original meter will be cancelled.
In order to ensure the accuracy of measurement and evaluation, a functional reactive power pulse power meter is set up separately at 110kV line, 35kV line and 6kV distribution line feeder, and the pulse information is sent to the microcomputer monitoring system for monitoring and recording.
2.4.6.3 In the same period, the generator breaker, the main 6kV incoming line and the segmented circuit breaker are automatically quasi-synchronized. The manual quasi-synchronization period includes the automatic quasi-synchronization point and the circuit breaker that needs to be switched first and then disconnected.
In the current period, the new microcomputer-based automatic quasi-synchronization and manual quasi-synchronization devices and the communication interface with the microcomputer monitoring system were newly established.
In the automatic quasi-synchronization period, the servo motor of the main valve of the turbine is controlled by hard wiring and the voltage of the generator AVR is adjusted by the hard wiring.
The manual quasi-synchronization period can be controlled by the microcomputer monitoring system to control the turbine main valve servo motor adjustment frequency and control the generator AVR regulation voltage as a backup method for automatic quasi-synchronization. It can also be set to capture the difference frequency or frequency synchronization of non-automatic quasi-contemporaneous points at the same time. brake.
The process of the same period can be displayed through the computer monitor screen, and the original conventional system is cancelled during the same period.
2.4.6.4 Electrical Five Prevention This phase of the transformation will be achieved by the computer error prevention workstation and the transformation of the site of electrical anti-misoperation locking two kinds of voltage levels of the circuit breaker, disconnector, grounding switch operation and distribution Electrical devices are divided into five doors and other electrical gates to prevent blocking.
2.4.6.5 Standby power supply Self-powered voltage levels The standby power supply will be switched slowly by the microcomputer monitoring system with low voltage criteria.
Standby power supply from the investment level from high to low to achieve the order of self-investment, if the high voltage level backup power supply from the successful investment will be locked low voltage standby power supply from the vote.
The main transformer protection action will block the 110kV standby power supply from the input; the 35kV bus protection action will block the 35kV standby power supply from the input; the 6kV bus protection action will latch the 6kV standby supply from the input.
2.4.6.6 Low-cycle load shedding and low-frequency decoupling The low-cycle load-shedding point is the main 6kV substation feeder line. The low-cycle load shedding considers two-stage frequency and time. The first stage is implemented by a 6kV feeder integrated automation device, and the second stage is implemented by a microcomputer monitoring system.
The low-frequency solution point is mainly 110/3576kV three sides optional. The low frequency de-solving takes into account two levels of frequency and time and is implemented by a microcomputer monitoring system.
The frequency and time for low-cycle load shedding and low-frequency decoupling can be set as needed. After the low-frequency decoupling, the generators bring important load to the company.
2.4.6.7 Disturbance Recording In order to independently and accurately analyze electrical faults, it is proposed to set up an important analogue quantity and switch quantity recording wave for 110kV line, main transformer, generator and each level voltage bus of the microcomputer type fault recording screen.
2.4.6.86kV Grounding Compensation 6kV Grounding Compensation Grounding Transformation and Arc Suppression Coil The self-contained arc-suppression coil tap adjuster can automatically adjust according to the compensation requirements. At the same time, the microcomputer monitoring system can also perform remote adjustment control of the tap.
2.4.6.9 Reactive Power Compensation In the current period, the main renovating main 6kV will be added with a new reactive compensation capacitor bank. The microcomputer monitoring system will base the generator AVR, on-load tap changer tap and reactive power compensation capacitor bank according to the compensation requirements. Circuit breaker switching implements remote joint regulation control.
2.4.7 Implementation steps Based on the above technical scenarios and the careful organization of the company in the future, we believe it is very hopeful to meet the company's requirements that “the step-by-step implementation and the time required for blackouts for each step of implementation should be as short as possibleâ€. The steps suggested are as follows:
(1) The DC system shall be equipped with new equipment first, and the DC feeder cables shall be replaced one by one. Finally, the existing DC system equipment and cables shall be removed;
(2) The UPS is newly installed and can be carried out at any time as required;
(3) The generator will only operate one unit at a time, and the excitation system and relay protection replacement can be carried out in separate units;
(4) The second transformation of 110kV can be carried out with a single device replacement;
(5) The 35kV distribution equipment shall be built before demolition, and the secondary equipment shall be implemented together with the new switch cabinet;
(6) The main 6kV power distribution device can be repaired and shut down at intervals, and the auxiliary auxiliary switch, on-site five-defense modification and secondary equipment modification can be carried out together. Secondary equipment modification Since the new local control box can be quickly put into use local control, and then choose the machine to carry out joint adjustment with the computer monitoring system communication interface will not cause long-term power outage;
(7) The transformation of the main control room can be based on the design plan to install a new screen at the screen location, and then gradually remove the cancel screen to install the remaining new screen gradually, and finally remove all intended to cancel the screen after the main control room room separation and appropriate decoration;
(8) The main control room cable transition, because the use of computer monitoring system to enter the main control cable is greatly reduced, new or new cable can be considered appropriate to leave a certain length along the edge of the cable sandwich first laying to the new screen of the current period, pending demolition After the cable, press the planning channel in place.
Concluding Remarks We believe that the above solutions are technically advanced and mature, and site implementation is also feasible. Plus, the preliminary estimation of the secondary part of the electrical transformation of the current period will require about RMB 4 million, which will be more reliable for the Tiantianhua Power Plant. The power supply has greatly improved the company's chemical safety production reliability. It should be said that it is a very effective and worthwhile investment in technological transformation.
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