The total capacity of 5 units is 184MW, of which Chencun has 3x50MW units and Jicun has 2x17MW units. The old-fashioned electromagnetic type protection used in the present There are many problems in the long-term operation of the field. Combined with the technical transformation project, in May 1998, the main transformer of Ji Village No. 2 was put into operation, and the WBZ-02 type transformer was protected by microcomputer (the difference of the transformer) Dynamic protection has been tested by regional and external faults). In December 1998, Chencun No. 2 generator transformer group put into operation a WFBZ-01 microcomputer protection. In April 1999, combined with the computer monitoring and AGC construction of Chencun No. 1 machine, the electromagnetic protection of No. 1 generator and No. 1 main transformer (220kV/120MVA autotransformer) was further improved. Change, using LFP-900 type microcomputer protection. March 2000~2001 Electromagnetic protection of Chencun No. 3 generator transformer group and Jicun No. 1 generator, No. 1 main transformer and Jicun No. 2 generator in March of each year Replace with LFP-900 microcomputer protection. Generator and transformer microcomputer protection is easy to solve traditional electromagnetic type Protecting hard-to-solve computing and logic issues, improving and improving protection performance. Due to the condition and operation of the primary equipment of the power system The mode is complicated, and the operation experience of microcomputer component protection still needs to be summarized and improved. The correct rate of protection for generators and transformers in the power grid is not high. In the case of application, study the internal structure and technical performance of the protection device, reasonably select the type, and propose a correct and reasonable protection configuration group screen In this case, the configuration and sensitivity of the component protection are both satisfied with the operation requirements of the main device, and the shortcomings of the previous electromagnetic protection are solved. Running table Ming, the selection configuration and technical transformation work carried out was successful. Analysis of Application and Operation of 1WBZ-02 Transformer Microcomputer Protection 315CXV110, protection uses WBZ-02 type transformer microcomputer protection. Protection configuration transformer differential protection, backup protection, switching protection, They are borne by three independent CPUs and have dedicated monitoring CPU units. Provide differential protection of the second harmonic brake, switch protection Backup protection for protection and reactive phase and ground faults. 1.1 Action analysis On May 13, 1998, the weight of the No. 2 main transformer occurred. Gas protection action, the analysis is that the switching protection circuit board has a low operating voltage of the relay, and the misoperation occurs under the interference. The method of high relay operating voltage is solved, and the operation after the shortage is normal. September 24, 1999, on the 35kV side of the main transformer No. 2 A and C phase breakdown faults occur in the cable, and the main transformer microcomputer differential protection Correct action avoids the expansion of the fault range. On July 23, 2000, the current of the TA terminal box of the 110kV bypass busbar occurred twice. When the 2QP pressure plate of the secondary circuit of the high voltage side of the main transformer of the No. 2 main transformer is cut off, one end is accidentally touched to the ground, causing the main transformer k of the main transformer to be differentially protected. The TA current loop is grounded at two points to make the main transformer. The differential protection 110kV side TA generates a differential current trip twice. The reason for the analysis is to prevent the occurrence of differential protection TA secondary loop multi-point connection About the author: Li Changgui (1962-), male, Anhui Huoshan, engineer, deputy director of Chencun Hydropower Station, engaged in production technology and operation management of hydropower plants. E-mail: AHJXZEB135sohu.com China Powerbook7 Ground (already a little protective ground), because the microcomputer differential protection action is sensitive, The differential current generated by multi-point grounding under normal load current will cause protection malfunction. In the actual operation, when the bypass bus switch is operated with the high-m side switch of the main transformer, the main transformer differential protection ta secondary current is performed. When the circuit switching platen is operated, reliable safety measures must be taken to prevent multi-point grounding of the TA secondary circuit. 1.2 Analysis of application characteristics of the device WBZ-02 protects liquid crystal display with Chinese characters convenient and intuitive, real-time The current of the differential protection difference circuit and the magnitude of each phase current are displayed to avoid the differential protection malfunction caused by the TA polarity connection. Transformer differential The protected three-sided TA secondary wiring still uses the traditional wiring principle. The current phase angle adjustment is not performed in the protection program. WBZ-02 can print fault information and sampled value report of fault amount, analyze fault condition Sampling value conversion is required. Application and Operation Analysis of 2WFBZ-01 Generator Transformer Group Microcomputer Protection Chencun No. 2 generator transformer group adopts WFBZ-01 type micro Machine protection, which is carried out by 3 independent CPUs, adopts the method of generator protection and transformer protection cross configuration to protect the configuration to improve The operational reliability of the entire set of microcomputer protection. Protection configuration CPU1: generator differential, stator single-phase grounding, overvoltage, phase-to-phase voltage loss, excitation cancellation Loss, SF6 switch low air pressure, main transformer light, heavy gas, TA disconnected. CPU2: generator crossover, demagnetization, negative sequence overcurrent, low voltage overcurrent, positive sequence Overload, zero-sequence current in the main transformer direction, TV disconnection. CPU3: main transformer differential, main transformer neutral point gap zero sequence, neutral point zero sequence Current. 2.1 No. 2 generator transformer group WFBZ-01 protection application solved problem Generator protection increases the excitation of the original electromagnetic protection Protection, that is, the generator de-excitation switch FMK, the exciter de-excitation switch LMK, the LK switch of the main excitation circuit when the electric brake is stopped The normally closed auxiliary contacts are connected in parallel with the HWJ normally open contacts of the outlet switch. When the unit is running, any switch trips to cause the transmission. The motor loses magnetism and the excitation disappears to protect the action. Since FMK uses DM4 plastic magnetic switch to its voltage type trip coil, the band in WFBZ-01 When the current keeps the outlet contact action, the FMK can't trip. For this reason, the DM4 de-excitation switch voltage type trip coil (8000, current) is used. 0.275A) parallel to one resistor at both ends (100 The method achieves the self-holding current requirement of the protection outlet, so that the FMK can trip reliably. Design of one-point grounding protection of generator rotor in WFBZ-01 It is necessary to superimpose a DC voltage of about +42V on the rotor voltage, which will result in a rotor-to-ground voltage monitoring table on the control panel of No. 2 generator. The measurement cannot be measured. The solution is to monitor the resistance of the measured rotor to ground using a protective device. Monitor CPU1 in front of the protection screen Digital display, the upper row of numbers *88* represents the dial switch number, the lower row of numbers For the rotor-to-ground insulation resistance (kn), when the insulation resistance is greater than 120kll, 119.9kn is displayed. The No. 2 machine rotor is grounded at one point. When the signal is blocked, because the device has additional power to the rotor, the safety measures for checking the insulation of the rotor should be disconnected from the operating power protected by the No. 2 unit. Neutral point zero sequence overcurrent protection and middle of the original No. 2 main transformer The point gap overcurrent protection shares a group of TAs. The problem is that the main transformer must be neutral when the neutral point of the main transformer is grounded. Point gap overcurrent protection exit; otherwise, under the outer fault, the main transformer Neutral point gap overcurrent protection can be mis-operated. For this technical change, a current transformer is added at the neutral point gap of the No. 2 main transformer. (LQJC-10 type, 200/5A). This is in the neutral point of the main transformer When the ground is running, the clearance overcurrent protection does not have to be out of operation, which improves the protection. Operational reliability. 2.2 Analysis of application characteristics of the device The WFBZ-01 protection display adopts LED digital tube, and the protection action signal adopts LED display. Protected investment, cutting without control words, mining Use DIP switch to cut and export pressure plate control. Transformer differential protection Adjust the unbalanced current of the TA with software. Protection export combination It is realized by a hard jumper on the circuit board, and the outlet relay contacts are self-holding with a current coil. WFBZ-01 cannot display real-time current, The voltage value can print the fault information and the sampled value report of the faulty child. Analysis on Application and Operation of 3LFP-900 Generator and Transformer Microcomputer Protection 972A, 973E) is a dual CPU structure that protects the CPU from protection Yes, manage the CPU to complete various management functions, with friendly man-machine interface. The management CPU has an independent protection total starting element, which improves The reliability of the protection device. Protection configuration LFP-981 device includes generator unit high Sensitive cross-section, stator grounding, demagnetization, overvoltage, composite voltage overcurrent, Reverse power protection and symmetrical overload, negative sequence overload signal, TV off Line discrimination, three-phase operation loop. LFP-982 device includes generator longitudinal difference (ratio differential), rotor 1, 2 point grounding, negative sequence overcurrent, phase modulation Loss of pressure, non-electricity protection and TA disconnection discrimination 3LFP-972A device (main transformer differential protection) including second harmonic braking ratio differential, Differential quick disconnect. LFP-973E device: main transformer 110kV, 220kV side backup protection (each set of devices) including composite voltage direction Flow protection, directional zero sequence overcurrent protection, overload signal and starting main transformer cooler. LFP-973F device: single transformer 10.5kV low-voltage side single-phase grounding signal and main transformer common coil overload signal. LFP-973D' device: light and heavy gas protection of main transformer, cold But the device is out of power failure. SF6 switch low pressure alarm and other non-electricity (re-mobilization) Protection and three-phase operation loop. 3.1 Problems solved in the application The original Chencun No. 1 generator stator grounding protection is installed in No. 1 main transformer On the pressure protection screen, there is no stator grounding protection during the startup of the generator. Protection function. Considering the actual situation of the equipment at the site, the generator is this time. Configure stator grounding protection, but when the generator is out of service, the main transformer is shipped No single-phase grounding monitoring on the 10.5kV low-voltage side, due to the 10.5kV busbar Long and not closed busbars, so add single-phase grounding protection on the 10.5kV side of the main transformer. In order to realize the generator stator grounding protection function, LFP-981 is installed. The voltage measurement circuit is connected to the Y wiring with 3 small TVs. The phase voltage of the generator is output, and the TV outlet of the generator is connected with V/V. The voltage, so the original TV is replaced by a three-phase five-column TV. Use secondary B phase grounding, neutral point plus breakdown fuse to meet the generator synchronous installation Set requirements. Therefore, when replacing the microcomputer protection, it is necessary to The secondary equipment is modified to obtain better protection. Lord 1 Transformer original autotransformer zero sequence differential protection configuration canceled, microcomputer differential protection LFP-972A single phase ground fault occurred inside the main transformer The sensitivity is satisfied (the original electromagnetic type BCH-4 is not satisfied). The main transformer longitudinal differential protection of No. 1 has a total of 4 sides TA, and the secondary parallel connection between the high-voltage side TA of the plant and the low-voltage side TA of the main transformer is taken as a group of TA leads. People to LFP-972A, developed during the protection current vector test A reasonable short-circuit test method is used to identify the correctness of the 2-side TA wiring. 3.2 Analysis of protection actions Route 485 occurred due to The permanent failure of the tree discharge and the grounding of the fault and the slow development of the fault, the LFP-941A microcomputer line protection trips after the coincidence of the jump, the recording When the fault zero-sequence current is displayed, the time is large and small, causing the 941A protection to start for a long time. The device self-test sends an error message, and it is judged that there is a TA disconnection and Fixed value setting error fault, blocking protection exit (protection program is designed in Blocking protection exit when sending TA disconnection alarm, currently has procedures version upgrade). Subsequently, the fault current suddenly increases due to the discharge, and the microcomputer protection outlet of the 485 line has been blocked, causing No. 1 The zero-sequence current I segment protection action of the main transformer 110kV side 973E trips, which plays the role of backup protection. Therefore strengthening the main change Backup protection is critical to the safe operation of the site. "Light" signal, No. 1 main transformer protection screen LFP-973F liquid crystal display *Uogy*, ie 3f /. Action signal, test control screen 10.5kV side The relative voltages of the TV voltmeters A, B, and C are 5.5 and 8.4, respectively. 4.6kV, the initial judgment is mainly low, and the EE side C phase is grounded. On the 1st The main transformer 10.5kV system was inspected and found that the 10kV busway was injected into the C-phase busbar by the water pipe bursting in the downstream side wall. on. The single-phase grounding protection of the low-voltage side of the main transformer is used to signal the reliable operation. An accident in which an outlet three-phase short circuit occurs on the low voltage side of the main transformer is avoided. 3.3 Analysis of application characteristics of the device LFP_900 type protects liquid crystal display information and displays real time /, f /, difference flow / value and / and phase sequence, phase, etc., with direction guarantee The correctness of the power direction of the guard is determined by the use of self-produced 3?, 3/. ,protection The direction is clear and the physical concept is clear. In order to protect the outside of the computer protection The circuit is closed and the correct investment operation provides technical guarantee and is now Field debugging is convenient. LFP-972A transformer differential protection TA adopts Y wiring, the current compensation coefficient is adjusted by the BCD switch to adjust the TA unbalanced current, and the load is measured to observe whether the differential current is balanced. Guarantee The protection exit combination mode adopts the software trip matrix to set the flexible application in the field, and the protection exit adopts the delay 200Ms trip pulse mode. In the case of the excitation disappearance protection action, the voltage type tripping coil of the DM4 type de-excitation switch is used for the FMK to ensure reliable demagnetization. Protection The fault recording function can capture the excitation inrush current waveform when the main transformer is turned on, and protect the fault current, voltage waveform and protection. Action exit switch quantity. ' 4 generators, transformers, microcomputer protection related technical issues Explore 4.1 Test on the two sides of the LFP-982 generator differential protection Consider the effects of transient saturation The scene occurred when the unit was connected to the grid due to the problem of the exit switch mechanism. Causes grid-connected impact, because the inrush current contains a large non-periodic component, and the degree of saturation is different when the TA characteristics on both sides are inconsistent. The flow causes the differential protection action of the LFP-982 generator, because This should be given attention to the selection and installation of TA on both sides. The measure is to replace the model of the TA on both sides of the generator to the same model, that is, the volt-ampere characteristics are the same, and modify the protection program of the upgraded LFP-982 to be anti-TA saturation program. The setting of the LFP-982 differential protection is not set. Can be too sensitive, still need to be explored and improved in the setting scheme Improve its operational reliability. 4.2 Understanding of Improving the Correct Action Level of Microcomputer Components Protection From the action situation since the microcomputer protection was put into operation, 35, 110, High correct operation rate of LFP-900 microcomputer protection for 220kV line Up to 100%, and the generator and transformer microcomputer protection can operate correctly when the fault occurs in the area, and the incorrect action occurs when the fault occurs outside the area. Because the protection principle needs to be improved in terms of fastness and reliability, such as generator differential protection (the original BCH-2 is fast saturated by non-periodic components). The converter works.) If the criterion for increasing the non-periodic component is increased, the differential protection will delay the exit when the fault occurs in the area, which is not conducive to fast. Remove the fault. Second, there are hidden dangers in the outer loop, the old equipment loop and characteristics Can meet the operational requirements of electromagnetic protection, but can not meet the operational requirements of microcomputer protection, these must be added in the future technical transformation work Improve. At the same time, it is necessary to strengthen the analysis of the action behavior of microcomputer protection. 4.3 Loss of magnetic protection can play the role of unit power-on protection In the start-up commissioning of a 30MW unit The hidden danger of the 6.3kV outlet switch of the generator under static current is the real machine simulation test: the generator is accidentally closed and shocked at rest. The current is 4.5 times the rated current and contains a large aperiodic component. Asynchronous impedance loss-of-magnetism protection in WFB-100 microcomputer protection 0.3s action trip, action jump after 2s lower than low voltage memory overcurrent protection The brake removal fault is much faster, check the generator end and zero boost Grinding No abnormalities, greatly reducing the damage to the generator. Visible, in the middle of the ', small The micro-machine protection of the generator has the characteristics of asynchronous impedance circle. The de-magnetization protection should be properly set and jumped, which can be used as the unit for power-on protection. The safe operation is very beneficial. In the current transformation of the sister-in-law, the static self-excited and controlled silicon excitation system is adopted to prevent the unit from being demagnetized. The scope of the barrier, the loss of magnetic protection is also very important. When the unit is out of magnetism Tripped by the generator low-voltage over-current protection action, the action time is much longer than the action time of the loss-of-magnetic protection:> 4.4 Adding the main transformer direction to the generator transformer unit unit wiring Sequence current protection Additional main transformer direction zero sequence current protection (direction pointing The main transformer side, the operating time limit is Os) is due to the original electromagnetic type main transformer differential protection on the high voltage side of the main transformer. Single phase ground fault time The sensitivity is not enough. It happened in the grid connection of Chencun No. 3 generator transformer group (the main transformer is not grounded), the high voltage side switch of the main transformer is not complete. When the closing gate is connected, the main transformer neutral point overvoltage is caused, the neutral point arrester* is worn, and the main transformer direction zero sequence current protection Os action outlet trips. The main transformer differential protection does not move, which plays the role of the main protection backup. At present, the sensitivity of the main transformer microcomputer differential protection is very high (the whole The value is 0.3/,.), so it is not necessary to add the zero-sequence current protection of the main transformer direction from the sensitivity consideration, but considering the current microcomputer main insurance The protection configuration failed to adopt dualization due to the cost factor, and the added main transformer direction zero-sequence current protection? In the microcomputer backup protection chassis, Therefore, adding the zero-sequence current protection in the direction of the main transformer has a great effect on improving the safe operation level of the main transformer. Visible, microcomputer protected The configuration should take into account all aspects of the factors to make the protection configuration reasonable and meet the requirements of on-site operation = 4.5 When the generator excitation mode is changed, the protection control word should be modified in time. Ji Village No. 1 and No. 2 generators were transformed from the excitation method of the original exciter to After the static self-excited microcomputer can control the excitation mode of the Gui, when the phase-to-phase fault occurs in the generator U, the protection of the short-circuit current will affect the protection action. Reliability, so the memory characteristics of the overcurrent protection in the software. For self-excited generators, after the LFP-982 composite voltage overcurrent protection is activated, the overcurrent components are stretched for 15s, so that the protection can be reliably operated. ? Control word *ZBL* when the protection device is used for self-excited generator “1*, only change the control word of the microcomputer protection to improve the protection performance. 4.6 The differential protection of the locked generator when the electric brake is stopped must be reliable in the normal shutdown of the hydropower generator of the peaking hydropower plant. Dynamic stop technology, when the machine is stopped, the generator stator is out of n three-phase short circuit, and a constant brake excitation current is added to the rotor winding. The road switch installation position is in the generator differential protection zone. Therefore, receiving electricity The main protection against braking effects is generator differential protection. In order to prevent misoperation, double blocking contacts are introduced from the electric brake screen and the local LCU screen. To the generator protection screen, the generator differential protection is blocked for a short time of about 3 minutes during the shutdown of the unit. 4.7 Cancel the mutual jump mode between the main transformer neutral point protection. The main transformer of Chencun No. 2 and No. 3 and the main transformer of Ji Village No. 1 and No. 2 Neutral point current and voltage protection H has been carried out after using microcomputer protection Perfection, increase the neutral point gap current TA of the main transformer, and set up the independent main transformer neutral point zero sequence current protection, gap Zero sequence current protection and zero sequence overvoltage protection. Therefore, the original transformer of No. 1~3 of Chencun Village and the neutral point protection room of No.1 and No.2 main transformers of Ji Village The mutual jump mode can be canceled according to the counter-measurement of component protection. 4.8 Handle the operation mode of the equipment and the reliability of the protection operation Relationship To avoid the secondary circuit cut when the device operation mode changes once In the event of a change in protection, it is necessary to cancel the unreasonable operation mode. The village used to have only one three-volume transformer, and the other was a two-volume transformer. The technical change was replaced by a three-volume transformer, plus the high voltage of the main transformer. All switches have been replaced from SW4-110 to ABB before the switch g_LTB- The 145 type SF6 switch, so the reliability of power supply has been greatly improved. Therefore The problem and existence of the original secondary high-voltage switch operation and the main transformer differential protection TA secondary circuit switching using 110kV side-mother switch The protection of the dead zone problem will not exist with the cancellation of this mode of operation. Reduce the weak points in the field, the operational reliability of the microcomputer protection will have A big increase. 4.9 Must pay attention to the upgrade and replacement of the microcomputer protection program The version number of the microcomputer protection program must be recorded and archived. through Through the accumulation of computer protection operation experience, especially for the motion analysis of some accidental faults, the program of microcomputer protection is continuously improved and updated. Therefore, it is necessary to contact the manufacturer in time to replace the protection program chip in time. Ensure the excellent performance of the microcomputer protection. 4.10 to understand and master the new principle of microcomputer protection Such as WFBZ-01 generator rotor point grounding protection due to It is necessary to superimpose the DC voltage on the negative pole of the rotor, which causes the rotor-to-ground voltage monitoring meter on the unit control panel to be unmeasurable. The measured rotor of the protective device is used to monitor the ground resistance. The LFP-982 generator rotor is grounded at one point and uses switching sampling. The law does not affect the measurement of the rotor-to-ground voltage monitoring meter. The rotor-to-ground insulation resistance is displayed in real time during the line, but the hydro-motor unit with frequent start-stop cannot monitor the rotor of the generator when the unit is shut down for standby. insulation. Implement the same functionality due to differences in software programming Protection of the balance factor due to the TA ratio and the Y/A transformation problem The calculation formulas of the constant and the differential flow are different, so pay attention to compare and prevent An error occurred. 4.11 Strengthening the technical management of on-site operation of microcomputer protection On-site management of the whole station microcomputer protection fixed value area The operating instructions of the microcomputer protection site are specified, and each operating value area of ​​the microcomputer protection is specified and clearly marked on the protection screen to prevent the protection of the fixed value area. Misoperation to prevent protection from running in a fixed-value zone (due to each micro The machine protection chassis can store 10 sets of protection settings) to avoid protection and rejection. Realized by the operating personnel when the system operation mode changes Adjust the protection setting value effectively, effectively shorten the operation time when r accident handling and normal operation mode change, and improve the safe operation water on site. Volume 36 Li Changgui, etc.: Fully Microcomputerized Technical Transformation and Operation Analysis of Generators and Transformers Protection Ping played a positive role. 5 application analysis (1) The upgrade of microcomputer protection is very fast, and should be as far as possible for a plant. Selecting the same type of protection can greatly reduce spare parts and facilitate The field personnel mastered. (2) The microcomputer protection should be sufficient when designing and selecting Consider the scalability, otherwise the expansion performance will be affected after the device is manufactured. Limiting, modifying, and adding devices can affect the operational reliability of the device. (3) The principle and criteria of microcomputer protection are better than electromagnetic protection, so The action is sensitive, and the external circuit design including anti-interference is required to comply with the relevant regulations of the microcomputer protection. (4) Microcomputer protection setting It is necessary to combine the calculation guidelines for generator and transformer relay protection and the actual situation on site. The improvement of protection sensitivity requires that the device be in a more Good operating conditions. (5) Because the microcomputer protection relies on the program to achieve insurance The function of the protection, the field personnel must master the hardware structure and logic block diagram of the microcomputer protection, and the alarm signal and the blocking signal sent by the device should be adopted. Take the appropriate processing method. (6) In the on-site technical reform, new and old protection To save, we must do a good job in the technical management of new protection and investment, such as running Formulation of instructions, strengthening training for field operators. At the same time Technical transformation of public equipment, such as the conversion of the light plate signal from the bulb type to the LED type, and the reliability of the control power supply. Outer The transformation of the loop equipment must keep pace with the transformation of the microcomputer protection, (7) Microcomputer protection provides a variety of information and prints out accident reports. Through nearly four years of operation, the device comes with fault information and fault waveforms. The printing function provides great convenience for accident analysis and on-site processing of problems. (8) 5 generators and 5 transformers of Chencun Hydropower Station The device has achieved successful experience in the technical transformation of microcomputer protection, eliminating the hidden dangers of the original electromagnetic protection, and raising Chen Cun The safe operation level of hydropower stations in the power system. - Electric Chain Saw,Hand Held Chain Saw,Lithium Battery Electric Saw,Electric Cordless Chainsaw Dtmade Manufacturing Co., LTD , https://www.dtmade.com
Technical transformation and operation analysis of generator and transformer protection
Chencun Hydropower Station is currently the largest hydropower station in Anhui Province, with installed capacity