A black start system and method for a 500kV voltage level three-quarters connection hydropower station

Abstract

The present invention discloses a black start system and method for a 500kV voltage level four-thirds connection hydropower station, which mainly comprises a diesel generator, a hydro-turbine generator, a step-up transformer, and a first 500kV line and a second 500kV line connected to the four-thirds connection. A generator-transformer-line self-excitation test is carried out to eliminate the hidden danger of self-excitation oscillation at startup, and the line overvoltage multiple is determined by using the diesel generator to provide a reference for the voltage limit on the high-voltage side of the black start step-up transformer. The hydro-turbine generator is started by the diesel generator, and the hydro-turbine generator is charged with the step-up transformer to charge the line, and the turbine is restored to operate with a 10kV busbar load island for plant use. The present invention improves the safety and controllability of the black start from multiple angles, such as setting a diesel generator standby power supply, modifying an overvoltage setting, modifying an underexcitation limit setting, adopting automatic excitation AVR control, investing a black start pressure plate, a single-side voltage-free closing mode of a grid-connected switch, and reasonably simplifying the switch and knife switch operation, thereby saving the black start time.

Description

Technical Field

[0001] The invention belongs to the technical field of black start of a hydropower station, and in particular relates to a black start system and method for a 500kV voltage level three-quarter connection hydropower station. Background Art

[0002] Black start is when the power grid loses power due to an extreme fault, and the power plant with self-starting capability is the first to supply power, and the power supply scope is gradually expanded in a "spark-starting" manner until the normal operation of the entire power grid is restored. As a security guard for power grids in various countries, black start can reduce the power outage losses caused by major natural disasters. Many black start examples at home and abroad have shown that black start is of great significance to the safety of power grids and national security. In order to ensure the safe and stable operation of the power grid and standardize the operation and management of black start equipment, the power grid has successively issued a number of black start-related rules and regulations in accordance with relevant national laws, regulations and industry standards, and provided economic compensation to power plants with black start capabilities. Power plants with conditions attach great importance to it and actively cooperate with the power grid to carry out black start capacity building and testing. Carrying out hydropower black start tests can quickly restore the normal and stable operation of the power grid in a short period of time, minimize load and economic losses, and have significant social benefits.

[0003] The existing black start technology has the following defects and deficiencies: (1) The self-excitation judgment of the generator and step-up transformer with line black start is mostly based on theoretical analysis. It is necessary to judge the self-excitation from the perspective of actual experiments. Actual experiments can more accurately judge the self-excitation phenomenon; (2) The overvoltage multiples at the beginning and end of the black start line are mostly calculated by line distribution parameters, and then the voltage on the high-voltage side of the step-up transformer is determined according to the maximum allowable operating voltage at the end of the line. It has not yet been seen that the line overvoltage multiples are measured using diesel. The actual measurement is more accurate than the theoretical calculation results; (3) The generator overvoltage setting is not adjusted during the common hydropower black start. When charging the line, the excitation system is usually manually used. The generator voltage is built up to the rated voltage. After the grid switch is connected, a large amount of capacitive current in the line causes the voltage to exceed the rated value. The grid-connected signal to the excitation system and the speed control system is manually released, and the grid-connected switch is closed by manual short-circuiting, which reduces the safety of the black start. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a 500kV voltage level three-quarter connection hydropower station black start system and method, which has a simple structure and reasonable design, reduces the operating steps of operators, saves start-up time, and improves operational safety.

[0005] The present invention is achieved through the following technical solutions:

[0006] A 500kV voltage level three-quarter connection hydropower station black start system, comprising a diesel generator, a 10kV busbar for a plant, a hydro-generator, a first 500kV line, a first reactor and a second 500kV line;

[0007] The diesel generator is connected to the 10kV plant busbar via the first 10kV plant switch, the first 10kV plant knife switch, and the second 10kV plant switch in sequence;

[0008] The 10kV plant busbar passes through the third 10kV plant switch and the high-voltage plant transformer in sequence;

[0009] The grounding end of the hydro-generator is grounded via a neutral point grounding knife switch, and the power generation end is connected in sequence via a generator outlet circuit breaker, a generator outlet knife switch, a step-up transformer and a first high-voltage 500kV knife switch;

[0010] The second 500kV line is connected to the first 500kV line via the eighth high-voltage 500kV knife switch, the ninth high-voltage 500kV knife switch, the third high-voltage 500kV circuit breaker, the tenth high-voltage 500kV knife switch, the second high-voltage 500kV knife switch, the first high-voltage 500kV circuit breaker, the third high-voltage 500kV knife switch, and the fourth high-voltage 500kV knife switch in sequence;

[0011] One end of the first reactor is grounded via the second reactor, and the other end is connected to the common point where the fourth high-voltage 500kV knife switch and the first 500kV line are connected via a fifth high-voltage 500kV knife switch.

[0012] The high-voltage plant transformer T is connected to the common point where the generator outlet knife switch and the step-up transformer are connected;

[0013] The first high-voltage 500kV knife switch T is connected to a common point where the second high-voltage 500kV knife switch and the tenth high-voltage 500kV knife switch are connected.

[0014] Preferably, it also includes a first 500kV busbar, a second 500kV busbar and a backup power supply;

[0015] The first 500kV busbar is sequentially connected to the common point where the eighth high-voltage 500kV knife switch and the ninth high-voltage 500kV knife switch are connected after being connected by a T-type connection via the sixth high-voltage 500kV knife switch, the second high-voltage 500kV circuit breaker, and the seventh high-voltage 500kV knife switch;

[0016] The second 500kV busbar is sequentially connected to the common point where the third high-voltage 500kV knife switch and the fourth high-voltage 500kV knife switch are connected via the twelfth high-voltage 500kV knife switch, the fourth high-voltage 500kV circuit breaker, and the eleventh high-voltage 500kV knife switch;

[0017] The backup power supply is connected to the common point where the first 10kV switch for plant use and the first 10kV knife switch for plant use are connected after passing through the fourth 10kV switch for plant use;

[0018] The diesel generator serves as the first safety backup power supply for the black start of the hydro-generator, and the backup power supply serves as the second safety backup power supply for the black start of the hydro-generator.

[0019] Furthermore, when conducting the black start self-excitation test of the hydro-turbine generator, step-up transformer and the first 500kV line, the overvoltage protection setting of the hydro-turbine generator is set to 115V, the delay time is set to 0s, and the tripping logic is modified to disconnect the generator outlet circuit breaker, the third plant 10kV switch, the third high-voltage 500kV circuit breaker and the fourth high-voltage 500kV circuit breaker; adjust the speed of the hydro-turbine generator to 104.2r / min; close the neutral point grounding switch, the generator outlet circuit breaker, the generator outlet switch, the first high-voltage 500kV switch, the second high-voltage 500kV switch, the first high-voltage 500kV circuit breaker, the third high-voltage 500kV switch, the fourth high-voltage 500kV switch and the fifth high-voltage 500kV switch.

[0020] Furthermore, when conducting the black start self-excitation test of the hydro-generator, step-up transformer and the second 500kV line, the third plant 10kV switch, the first high-voltage 500kV circuit breaker and the second high-voltage 500kV circuit breaker are disconnected; the speed of the hydro-generator is adjusted to 104.2r / min; the neutral point grounding switch, the generator outlet circuit breaker, the generator outlet switch, the first high-voltage 500kV switch, the eighth high-voltage 500kV switch, the ninth high-voltage 500kV switch, the third high-voltage 500kV circuit breaker and the tenth high-voltage 500kV switch are closed.

[0021] Furthermore, when conducting the black start self-excitation test of the hydro-generator, the step-up transformer, the first 500kV line and the second 500kV line, the third plant 10kV switch, the second high-voltage 500kV circuit breaker and the fourth high-voltage 500kV circuit breaker are disconnected; the speed of the hydro-generator is adjusted to 104.2r / min; the neutral point grounding switch, the generator outlet circuit breaker, the generator outlet switch, the first high-voltage 500kV switch, the second high-voltage 500kV switch, the first high-voltage 500kV circuit breaker, the third high-voltage 500kV switch, the fourth high-voltage 500kV switch, the fifth high-voltage 500kV switch, the eighth high-voltage 500kV switch, the ninth high-voltage 500kV switch, the third high-voltage 500kV circuit breaker and the tenth high-voltage 500kV switch are closed.

[0022] Furthermore, when conducting the overvoltage test on the diesel generator, the high-voltage plant transformer, the step-up transformer and the first 500kV line, disconnect the fourth plant 10kV switch, the generator outlet circuit breaker, the third high-voltage 500kV circuit breaker and the fourth high-voltage 500kV circuit breaker; start the diesel generator and build up the voltage to the rated voltage of 10kV; close the first plant 10kV switch, the first plant 10kV knife switch, the second plant 10kV switch, the third plant 10kV switch, the first high-voltage 500kV knife switch, the second high-voltage 500kV knife switch, the first high-voltage 500kV circuit breaker, the third high-voltage 500kV knife switch, the fourth high-voltage 500kV knife switch and the fifth high-voltage 500kV knife switch.

[0023] Furthermore, when conducting overvoltage tests on the diesel generator, high-voltage plant transformer, step-up transformer and second 500kV line, disconnect the fourth plant 10kV switch, generator outlet circuit breaker, first high-voltage 500kV circuit breaker and second high-voltage 500kV circuit breaker; start the diesel generator and build up the voltage to the rated voltage of 10kV; close the first plant 10kV switch, the first plant 10kV knife switch, the second plant 10kV switch, the third plant 10kV switch, the first high-voltage 500kV knife switch, the eighth high-voltage 500kV knife switch, the ninth high-voltage 500kV knife switch, the third high-voltage 500kV circuit breaker and the tenth high-voltage 500kV knife switch.

[0024] Furthermore, when conducting overvoltage tests on the diesel generator, high-voltage plant transformer, step-up transformer, first 500kV line and second 500kV line, disconnect the fourth plant 10kV switch, generator outlet circuit breaker, second high-voltage 500kV circuit breaker and fourth high-voltage 500kV circuit breaker; start the diesel generator and build up the voltage to the rated voltage of 10kV; close the first plant 10kV switch, the first plant 10kV knife switch, the second plant 10kV switch, the third plant 10kV switch, the first high-voltage 500kV knife switch, the second high-voltage 500kV knife switch, the first high-voltage 500kV circuit breaker, the third high-voltage 500kV knife switch, the fourth high-voltage 500kV knife switch and the fifth high-voltage 500kV knife switch, the eighth high-voltage 500kV knife switch, the ninth high-voltage 500kV knife switch, the third high-voltage 500kV circuit breaker and the tenth high-voltage 500kV knife switch.

[0025] Furthermore, when the hydro-generator and the step-up transformer perform black start charging tests on the first 500kV line and the second 500kV line, the fourth plant 10kV switch, the third plant 10kV switch, the second high-voltage 500kV circuit breaker, and the fourth high-voltage 500kV circuit breaker are disconnected, and the neutral point grounding switch, the generator outlet circuit breaker, the generator outlet switch, the first high-voltage 500kV switch, the second high-voltage 500kV switch, the third high-voltage 500kV switch, the fourth high-voltage 500kV switch, the fifth high-voltage 500kV switch, the eighth high-voltage 500kV switch, the ninth high-voltage 500kV switch, the tenth high-voltage 500kV switch, the first high-voltage 500kV circuit breaker, and the third high-voltage 500kV circuit breaker are closed.

[0026] A black start method for a 500 kV voltage level three-quarters connection hydropower station comprises the following steps:

[0027] 1) Carry out preparation work for the black start test, and proceed to step 2) after all preliminary preparation work is completed;

[0028] 2) Conducting a self-excitation test of the hydro-generator and the step-up transformer on the first 500kV line or the second 500kV line, judging the self-excitation phenomenon according to whether the voltage and current signals of the hydro-generator, the first 500kV line and the second 500kV line oscillate, if there is no self-excitation phenomenon, proceeding to step 3), if there is self-excitation phenomenon, proceeding to step 6);

[0029] 3) using the diesel generator to carry out an overvoltage test on the first 500kV line or the second 500kV line, calculating the ratio n of the voltage at the end and the voltage at the beginning of the first 500kV line or the second 500kV line, dividing the maximum allowable operating voltage of 548kV at the end by n to determine the high-voltage side target value of the step-up transformer during black start, and then proceeding to step 4);

[0030] 4) Start the diesel generator to supply power to the 10kV bus load for the factory, conduct a black start charging test of the hydro-generator and the step-up transformer with the first 500kV line or the second 500kV line, check and confirm that the voltage indication and phase sequence at the end of the first 500kV line or the second 500kV line are correct, and proceed to step 5);

[0031] 5) The 10kV bus load for the power plant is restored to be powered by the hydro-generator, and the voltage indication of the 10kV bus for the power plant is checked and confirmed to be stable, and the variation range is less than or equal to 3% of the rated voltage 10kV, and then the process goes to step 6);

[0032] 6) The black start of the hydro-generator and the step-up transformer with the first 500kV line or the second 500kV line is completed.

[0033] Compared with the prior art, the present invention has the following beneficial technical effects:

[0034] The present invention carries out self-excitation and overvoltage tests before black start to judge whether there is a safety hazard of self-excitation oscillation during black start, determines the target voltage on the high-voltage side of the step-up transformer according to the overvoltage test result, and timely discovers the existing risks before black start; before black start, the primary and secondary equipment settings and operation modes are adjusted, the overvoltage setting, the low excitation limit setting, the circuit breaker and the single-side no-pressure control mode of the switch are modified, and the grid-connected signal is exited to the exciter speed control system, so as to ensure the safety of black start from the perspective of secondary circuit and control; during black start, the excitation system adopts the AVR automatic control mode to avoid line overvoltage caused by line capacitive current, uses a diesel generator to start the hydro-turbine generator, reasonably simplifies the operation of switches and knife switches, and promptly restores the plant 10kV bus load to the hydro-turbine generator after the black start is successful, so as to realize the hydro-turbine generator's self-contained plant power island operation mode, thereby improving the safety and controllability of black start, saving black start time, ensuring that the power supply of the hydro-turbine generator is sent out in time when the power grid loses power, and accelerating the reconstruction and recovery speed of the power grid.

[0035] Furthermore, the present invention adjusts the rated speed of the hydro-turbine generator through a generator-transformer-line self-excitation test to simulate normal operating conditions, pushes out the excitation system, modifies the overvoltage setting of the hydro-turbine generator to 115V, sets the delay time to 0s, modifies the tripping logic to disconnect the generator output circuit breaker, closes all switches and knife switches on the black start path, observes the voltage and current oscillations on the high-voltage side of the generator and the step-up transformer, promptly discovers the self-excitation condition in the black start path, and eliminates the safety hazards of the black start.

[0036] Furthermore, the present invention starts the diesel generator and builds up the voltage to the rated voltage, puts into high-voltage plant transformer and step-up transformer, calculates the voltage ratio between the end and the head end of the black start line to be sent, determines the voltage of the high-voltage side of the step-up transformer when the actual generator is black started with the step-up transformer, and prevents the voltage at the end of the line to be sent from exceeding the maximum allowable operating voltage.

[0037] Furthermore, the present invention uses the backup power supply as the second backup power supply of the diesel generator. When a black start is performed, the diesel generator cannot be started or pressure built up, and the backup power supply is used, thereby improving the reliability of the black start of the hydropower station and avoiding accidents of black start failure.

[0038] Furthermore, during black start, the present invention adopts an automatic excitation AVR mode for the excitation system, and the low excitation limit is set to the PQ curve value of the hydro-turbine generator to accurately control the generator and transformer voltages. When the line is put into operation with capacitive current to assist magnetization, the excitation current is automatically reduced to maintain a constant output voltage. At the same time, a black start-specific pressure plate and a single-sided no-voltage closing mode of the grid-connected switch are provided to reduce the risk of manual short-circuit node operation, and the excitation surge current is prevented from damaging the generator body by building up voltage with the generator and transformer and by using the empty charging line mode.

[0039] Furthermore, when the 10kV bus load for the factory is restored to be powered by the hydro-turbine generator, the diesel generator continues to operate normally. When the operation of the small island with the 10kV bus load for the factory is unstable, the diesel generator is put into use in time to ensure that the 10kV bus load for the factory does not lose power.

[0040] Furthermore, the present invention adjusts all switches on the path to a hot standby state before a black start, which can save black start time, speed up the black start power supply, and has high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a system principle block diagram of the present invention.

[0042] Figure 2 This is a principle block diagram of the first 500kV line self-excitation test of the present invention.

[0043] Figure 3 This is a principle block diagram of the second 500kV line self-excitation test of the present invention.

[0044] Figure 4 This is a principle block diagram of the self-excitation test of the first 500kV line and the second 500kV line of the present invention.

[0045] Figure 5 This is a principle block diagram of the first 500kV line overvoltage test of the present invention.

[0046] Figure 6 This is a second 500kV line overvoltage test principle block diagram of the present invention.

[0047] Figure 7 This is a block diagram of the overvoltage principle of the first 500kV line and the second 500kV line of the present invention.

[0048] Figure 8 This is a block diagram of the black start charging principle of the first 500kV line or the second 500kV line of the present invention.

[0049] Fig. 9 This is a block diagram of the black start recovery plant power supply principle of the present invention.

[0050] In the figure: 1-diesel generator; 2-10kV switch for the first plant; 3-10kV knife switch for the first plant; 4-10kV switch for the second plant; 5-10kV busbar for the plant; 6-10kV switch for the third plant; 7-high-voltage plant transformer; 8-neutral point grounding knife switch; 9-hydraulic generator; 10-generator outlet circuit breaker; 11-generator outlet knife switch; 12-step-up transformer; 13-1st high-voltage 500kV knife switch; 14-2nd high-voltage 500kV knife switch; 15-1st high-voltage 500kV circuit breaker; 16-3rd high-voltage 500kV knife switch; 17-4th high-voltage 500kV knife switch; 18-1st 500kV line; 19-5th high-voltage 500kV knife switch 1-100kV switch; 2-110kV switch; 3-120kV switch; 3-130kV switch; 3-140kV switch; 3-150kV switch; 3-160kV switch; 3-170kV switch; 3-180kV switch; 3-190kV switch; 4-200kV busbar; 5-350kV backup power supply; 6-10kV switch for plant use. DETAILED DESCRIPTION

[0051] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0052] The invention discloses a black start system and method for a 500kV voltage level four-thirds connection hydropower station, which mainly comprises a diesel generator, a hydro-turbine generator, a step-up transformer, and a first 500kV line and a second 500kV line connected to the four-thirds connection; a generator-transformer-line self-excitation test is carried out to eliminate the hidden danger of self-excitation oscillation at startup, and the line overvoltage multiple is determined by using the diesel generator to provide a reference for the voltage limit on the high-voltage side of the black start step-up transformer; the hydro-turbine generator is started by the diesel generator, and the hydro-turbine generator with the step-up transformer charges the line, and the turbine is restored to operate with a 10kV busbar load island for factory use; the invention can eliminate the technical difficulties existing in the black start process, and improve the safety and controllability of the black start from multiple angles such as setting a diesel generator standby power supply, modifying the overvoltage setting value, modifying the low excitation limit setting value, adopting automatic excitation AVR control, putting in a black start pressure plate, a single-side voltage-free closing mode of a grid-connected switch, and reasonably simplifying the switch and knife switch operation, thereby saving the black start time, ensuring that the hydro-turbine generator power supply is sent out in time when the power grid loses power, and accelerating the reconstruction and recovery speed of the power grid.

[0053] like Figure 1As shown, a 500kV voltage level three-quarter connection hydropower station black start system of the present invention comprises a diesel generator 1, a 10kV busbar 5 for a plant, a hydro-generator 9, a first 500kV line 18, a first reactor 20 and a second 500kV line 27;

[0054] The diesel generator 1 is connected to the 10kV plant bus 5 via the first 10kV plant switch 2, the first 10kV plant switch 3, and the second 10kV plant switch 4 in sequence;

[0055] The 10kV plant busbar 5 passes through the third 10kV plant switch 6 and the high-voltage plant transformer 7 in sequence;

[0056] The grounding end of the hydro-generator 9 is grounded via a neutral point grounding switch 8, and the power generation end is connected in sequence via a generator outlet circuit breaker 10, a generator outlet switch 11, a step-up transformer 12 and a first high-voltage 500 kV switch 13;

[0057] The second 500kV line 27 is connected to the first 500kV line 18 via the eighth high-voltage 500kV knife switch 26, the ninth high-voltage 500kV knife switch 28, the third high-voltage 500kV circuit breaker 29, the tenth high-voltage 500kV knife switch 30, the second high-voltage 500kV knife switch 14, the first high-voltage 500kV circuit breaker 15, the third high-voltage 500kV knife switch 16, and the fourth high-voltage 500kV knife switch 17 in sequence;

[0058] One end of the first reactor 20 is grounded via the second reactor 21, and the other end is connected to the common point where the fourth high-voltage 500kV knife switch 17 and the first 500kV line 18 are connected via a fifth high-voltage 500kV knife switch 19;

[0059] The high-voltage plant transformer 7T is connected to the common point where the generator outlet knife switch 11 and the step-up transformer 12 are connected;

[0060] The first high-voltage 500 kV knife switch 13T is connected to a common point where the second high-voltage 500 kV knife switch 14 and the tenth high-voltage 500 kV knife switch 30 are connected.

[0061] The diesel generator 1 is used for overvoltage test and black start initial stage to provide factory power for the hydro-generator 9. Its detailed parameters are as follows:

[0062] Rated capacity(kVA) Active power (kW) Rated power factor Rated voltage(V) 625 500 0.8 10500

[0063] After the first 500kV line 18 and the second 500kV line 27 lose power, the hydro-generator 9 starts in time and re-sends power to help the power grid recover power and start the power to be started. Its detailed parameters are as follows:

[0064] Rated capacity(MVA) Active power(MW) Rated power factor Rated speed (r / min) 777.8 700 0.9 104.2

[0065] like Figure 1 As shown, it also includes a first 500kV bus 22, a second 500kV bus 34 and a backup power supply 35;

[0066] The first 500kV busbar 22 is connected to the common point where the eighth high-voltage 500kV knife switch 26 and the ninth high-voltage 500kV knife switch 28 are connected after passing through the sixth high-voltage 500kV knife switch 23, the second high-voltage 500kV circuit breaker 24, and the seventh high-voltage 500kV knife switch 25 in sequence;

[0067] The second 500kV busbar 34 is connected to the common point where the third high-voltage 500kV knife switch 16 and the fourth high-voltage 500kV knife switch 17 are connected after passing through the twelfth high-voltage 500kV knife switch 33, the fourth high-voltage 500kV circuit breaker 32, and the eleventh high-voltage 500kV knife switch 31 in sequence;

[0068] The backup power supply 35 is connected to the common point where the first 10kV switch 2 and the first 10kV knife switch 3 are connected after passing through the fourth 10kV switch 36;

[0069] The diesel generator 1 serves as the first safety backup power supply for the black start of the hydro-generator 9 , and the backup power supply 35 serves as the second safety backup power supply for the black start of the hydro-generator 9 .

[0070] Self-excitation is actually a kind of parameter resonance. When the generator carries a capacitive load, under the matching of certain reactance parameters, even if the excitation current is very small, it is possible to produce parameter resonance due to the effect of excitation energy. For self-excitation of the generator, when the capacitive load carried by the generator reaches a certain index, the magnetic assistance generated by the capacitive current in the circuit will gradually increase the terminal voltage of the generator. The increased voltage will cause the capacitive current to increase, and the terminal voltage will increase again due to the magnetic assistance, causing the terminal voltage to increase spontaneously and become higher and higher. Although the terminal voltage of the generator caused by self-excitation will not increase infinitely, due to the decrease in capacitive reactance caused by the increase in the length of the transmission line, the terminal voltage will quickly produce a higher value during the gradual increase. In more serious cases, it will damage the insulation of the unit and the plant electrical equipment, bring unsafe factors to the equipment and the entire system, and even cause accidents. Therefore, the occurrence and severity of self-excitation will be one of the key issues related to whether the black start can be successfully carried out.

[0071] like Figure 2As shown, when the black start self-excitation test of the hydro-generator 9, the step-up transformer 12 and the first 500kV line 18 is performed, the overvoltage protection setting value of the hydro-generator 9 is set to 115V, the delay time is set to 0s, and the tripping logic is modified to disconnect the generator outlet circuit breaker 10, the third plant 10kV switch 6, the third high-voltage 500kV circuit breaker 29 and the fourth high-voltage 500kV circuit breaker 32; adjust the speed of the hydro-generator 9 to 104.2r / min; close the neutral point grounding knife switch 8, the generator outlet circuit breaker 10, the generator outlet knife switch 11, the first high-voltage 500kV knife switch 13, the second high-voltage 500kV knife switch 14, the first high-voltage 500kV circuit breaker 15, the third high-voltage 500kV knife switch 16, the fourth high-voltage 500kV knife switch 17 and the fifth high-voltage 500kV knife switch 19.

[0072] like Figure 3 As shown, when the black start self-excitation test of the hydro-generator, step-up transformer and the second 500kV line is carried out, when the black start self-excitation test of the hydro-generator 9, step-up transformer 12 and the second 500kV line 27 is carried out, the third plant 10kV switch 6, the first high-voltage 500kV circuit breaker 15 and the second high-voltage 500kV circuit breaker 24 are disconnected; the speed of the hydro-generator 9 is adjusted to 104.2r / min; the neutral point grounding switch 8, the generator outlet circuit breaker 10, the generator outlet switch 11, the first high-voltage 500kV switch 13, the eighth high-voltage 500kV switch 26, the ninth high-voltage 500kV switch 28, the third high-voltage 500kV circuit breaker 29 and the tenth high-voltage 500kV switch 30 are closed.

[0073] like Figure 4 As shown, when the black start self-excitation test of the hydro-generator 9, the step-up transformer 12, the first 500kV line 18 and the second 500kV line 27 is performed, the third plant 10kV switch 6, the second high-voltage 500kV circuit breaker 24 and the fourth high-voltage 500kV circuit breaker 32 are disconnected; the rotation speed of the hydro-generator 9 is adjusted to 104.2r / min; the neutral point grounding switch 8, the generator outlet circuit breaker 10, the generator outlet switch 11, the first high-voltage 500kV switch 13, the second high-voltage 500kV switch 14, the first high-voltage 500kV circuit breaker 15, the third high-voltage 500kV switch 16, the fourth high-voltage 500kV switch 17, the fifth high-voltage 500kV switch 19, the eighth high-voltage 500kV switch 26, the ninth high-voltage 500kV switch 28, the third high-voltage 500kV circuit breaker 29 and the tenth high-voltage 500kV switch 30 are closed.

[0074] When the end of the line is unloaded, the input impedance of the line is capacitive. The line capacitance effect not only makes the voltage at the end of the line higher than the beginning, but also makes the voltage at the beginning and end of the line higher than the electromotive force of the power supply, causing the power supply to generate overvoltage in the unloaded line.

[0075] like Figure 5 As shown, when the diesel generator 1, the high-voltage plant transformer 7, the step-up transformer 12, and the first 500kV line 18 are subjected to an overvoltage test, the fourth plant 10kV switch 36, the generator outlet circuit breaker 10, the third high-voltage 500kV circuit breaker 29, and the fourth high-voltage 500kV circuit breaker 32 are disconnected; the diesel generator 1 is started and the voltage is built up to the rated voltage of 10kV; the first plant 10kV switch 2, the first plant 10kV knife switch 3, the second plant 10kV switch 4, the third plant 10kV switch 6, the first high-voltage 500kV knife switch 13, the second high-voltage 500kV knife switch 14, the first high-voltage 500kV circuit breaker 15, the third high-voltage 500kV knife switch 16, the fourth high-voltage 500kV knife switch 17, and the fifth high-voltage 500kV knife switch 19 are closed; and the overvoltage multiple is calculated according to the ratio of the voltage at the end and the head end of the first 500kV line 18.

[0076] like Figure 6 As shown, when the diesel generator 1, the high-voltage plant transformer 7, the step-up transformer 12, and the second 500kV line 27 are subjected to an overvoltage test, the fourth plant 10kV switch 36, the generator outlet circuit breaker 10, the first high-voltage 500kV circuit breaker 15, and the second high-voltage 500kV circuit breaker 24 are disconnected; the diesel generator 1 is started and the voltage is built up to the rated voltage of 10kV; the first plant 10kV switch 2, the first plant 10kV knife switch 3, the second plant 10kV switch 4, the third plant 10kV switch 6, the first high-voltage 500kV knife switch 13, the eighth high-voltage 500kV knife switch 26, the ninth high-voltage 500kV knife switch 28, the third high-voltage 500kV circuit breaker 29, and the tenth high-voltage 500kV knife switch 30 are closed; and the overvoltage multiple is calculated according to the ratio of the voltage at the end and the head end of the second 500kV line 27.

[0077] like Figure 7As shown, when the diesel generator 1, the high-voltage plant transformer 7, the step-up transformer 12, the first 500kV line 18 and the second 500kV line 27 are overvoltage tested, the fourth plant 10kV switch 36, the generator outlet circuit breaker 10, the second high-voltage 500kV circuit breaker 24 and the fourth high-voltage 500kV circuit breaker 32 are disconnected; the diesel generator 1 is started and the voltage is built up to the rated voltage of 10kV; the first plant 10kV switch 2, the first plant 10kV knife switch 3, the second plant 10kV switch 4, the third plant 10kV switch 5 are closed, and ... 0kV switch 6, the first high-voltage 500kV knife switch 13, the second high-voltage 500kV knife switch 14, the first high-voltage 500kV circuit breaker 15, the third high-voltage 500kV knife switch 16, the fourth high-voltage 500kV knife switch 17 and the fifth high-voltage 500kV knife switch 19, the eighth high-voltage 500kV knife switch 26, the ninth high-voltage 500kV knife switch 28, the third high-voltage 500kV circuit breaker 29 and the tenth high-voltage 500kV knife switch 30; the overvoltage multiple is calculated according to the ratio of the end voltage and the head voltage of the first 500kV line 18 and the second 500kV line 27.

[0078] like Figure 8 and Fig. 9As shown, when the hydro-generator 9 and the step-up transformer 12 perform a black start charging test on the first 500kV line 18 and the second 500kV line 27, the fourth plant 10kV switch 36, the third plant 10kV switch 6, the second high-voltage 500kV circuit breaker 24, and the fourth high-voltage 500kV circuit breaker 32 are disconnected, and the neutral point grounding knife switch 8, the generator outlet circuit breaker 10, the generator outlet knife switch 11, the first high-voltage 500kV circuit breaker 24, and the fourth high-voltage 500kV circuit breaker 32 are closed. kV switch 13, the second high voltage 500kV switch 14, the third high voltage 500kV switch 16, the fourth high voltage 500kV switch 17, the fifth high voltage 500kV switch 19, the eighth high voltage 500kV switch 26, the ninth high voltage 500kV switch 28, the tenth high voltage 500kV switch 30, the first high voltage 500kV circuit breaker 15 and the third high voltage 500kV circuit breaker 29; check and confirm that the first 500kV line 18 and the first The voltage indication at the end of the second 500kV line 27 does not exceed the maximum allowable operating voltage of 548kV, and the phase sequence is correct; when the load of the plant 10kV bus 5 is restored, the second plant 10kV switch 4 is disconnected and the third plant 10kV switch 6 is closed; the excitation system of the hydro-generator 9 is provided with a black start pressure plate, which automatically releases the connection between the grid-connected signal of the generator output circuit breaker and the speed regulation and excitation system when it is put into use, and the excitation system of the hydro-generator 9 adopts the automatic excitation AVR mode to perform a black start charging test on the first 500kV line 18 or the second 500kV line 27; the low excitation limit of the excitation system of the hydro-generator 9 is set according to the generator PQ curve, (700MW, -294MVar), (525MW, -378Mvar), (350MW, -408MVar); the synchronous system of the hydro-generator 9 closes the generator output circuit breaker in a single-side no-voltage closing mode.

[0079] In this embodiment, a black start method for a 500 kV voltage level three-quarters connection hydropower station includes the following steps:

[0080] 1) Carry out preparation work for the black start test, and proceed to step 2) after all preliminary preparation work is completed;

[0081] 2) Conducting a self-excitation test of the hydro-generator 9 and the step-up transformer 12 on the first 500kV line 18) or the second 500kV line 27, judging the self-excitation phenomenon according to whether the voltage and current signals of the hydro-generator 9, the first 500kV line 18, and the second 500kV line 27 oscillate, if there is no self-excitation phenomenon, proceeding to step 3, if there is self-excitation phenomenon, proceeding to step 6);

[0082] 3) using the diesel generator 1 to carry out an overvoltage test on the first 500kV line 18 or the second 500kV line 27, calculating the voltage ratio n between the end and the head of the first 500kV line 18 or the second 500kV line 27, dividing the maximum allowable operating voltage of 548kV at the end by n to determine the high-voltage side target value of the step-up transformer 12 during black start, and then proceeding to step 4);

[0083] 4) Start the diesel generator 1 to supply power to the factory 10kV bus 5 load, conduct a black start charging test of the hydro-generator 9 and the step-up transformer 12 with the first 500kV line 18 or the second 500kV line 27, check and confirm that the terminal voltage indication and phase sequence of the first 500kV line 18 or the second 500kV line 27 are correct, and proceed to step 5);

[0084] 5) The load of the 10kV bus 5 for the power plant is restored and the power is supplied by the hydro-generator 9. Check and confirm that the voltage indication of the 10kV bus 5 for the power plant is stable, and the variation range is less than or equal to 3% of the rated voltage 10kV, and then proceed to step 6);

[0085] 6) The black start of the hydro-generator 9 and the step-up transformer 12 with the first 500 kV line 18 or the second 500 kV line 27 is completed.

[0086] In this embodiment, in the step 1), the operator operates the second high-voltage 500kV circuit breaker 24 and the fourth high-voltage 500kV circuit breaker 32 to switch to a cold standby state, and disconnects the fourth plant-use 10kV switch 36;

[0087] In the step 2), the operator sequentially adjusts the speed of the hydro-generator 9 to 104.2 r / min, closes the neutral point grounding switch 8, closes the generator outlet switch 11, closes the first high-voltage 500kV switch 13, closes the second high-voltage 500kV switch 14, closes the third high-voltage 500kV switch 16, the fourth high-voltage 500kV switch 17, the fifth high-voltage 500kV switch 19, closes the generator outlet circuit breaker 10 and the first high-voltage 500kV circuit breaker 15. If the voltage and current of the hydro-generator 9 and the first 500kV line 18 oscillate, self-excitation is generated, and a black start cannot be performed. The first high-voltage 500kV circuit breaker 15 is immediately disconnected. If no oscillation occurs, the first 500kV line 18 can be black-started, and the first high-voltage 500kV circuit breaker 15 is checked and confirmed to be in a disconnected state. The operator continues to sequentially close the eighth high-voltage 500kV switch 26, the ninth high-voltage 500kV switch 28, The tenth high-voltage 500kV knife switch 30 is closed, and the third high-voltage 500kV circuit breaker 29 is closed. If the voltage and current of the hydro-generator 9 and the second 500kV line 27 oscillate, self-excitation is generated, and a black start cannot be performed. The third high-voltage 500kV circuit breaker 29 is immediately disconnected. If no oscillation occurs, a black start of the second 500kV line 27 can be performed. The first high-voltage 500kV circuit breaker 15 is closed again ... the self-excitation is generated, and a black start cannot be performed. If the voltage and current of the 500kV line 27 and the first 500kV line 18 oscillate, self-excitation is generated, and black start cannot be performed. The third high-voltage 500kV circuit breaker 29 and the first high-voltage 500kV circuit breaker 15 are immediately disconnected. If no oscillation occurs, the second 500kV line 27 and the first 500kV line 18 can be black started, and then the generator outlet circuit breaker 10, the first high-voltage 500kV circuit breaker 15 and the third high-voltage 500kV circuit breaker 29 are disconnected;

[0088] In the step 3), the diesel generator 1 is first started and the voltage is built up to the rated voltage of 10kV, and the first 10kV switch 3, the first 10kV switch 2, the second 10kV switch 4, the third 10kV switch 6 and the first high-voltage 500kV circuit breaker 15 are closed in sequence, and the voltage ratio n1 between the first end and the end of the first 500kV line 18 is calculated, and the first high-voltage 500kV circuit breaker 15 is disconnected, and then the third high-voltage 500kV circuit breaker 29 is closed, and the voltage ratio n2 between the first end and the end of the second 500kV line 27 is calculated, and the circuit breaker 29 is closed again. The first high-voltage 500kV circuit breaker 15 calculates the voltage ratio n3 between the head end and the tail end of the first 500kV line 18, calculates the voltage ratio n4 between the head end and the tail end of the second 500kV line 27, selects the minimum value among 548 / n1, 548 / n2, 548 / n3, and 548 / n4 to determine the target voltage Vm of the high-voltage side of the step-up transformer 12 during black start, and finally disconnects the first plant-use 10kV switch 2, the second plant-use 10kV switch 4, the third plant-use 10kV switch 6, the first high-voltage 500kV circuit breaker 15, and the third high-voltage 500kV circuit breaker 29;

[0089] In the step 4), the operator sequentially closes the first 10kV switch 2 and the second 10kV switch 4, starts the diesel generator 1 to supply power to the 10kV bus 5 load, starts the hydro-generator 9 and sets the speed to 104.2r / min, closes the generator outlet circuit breaker 10, adjusts the high-voltage side voltage of the step-up transformer 12 to Vm, closes the first high-voltage 500kV circuit breaker 15, checks and confirms that the terminal voltage of the first 500kV line 18 is ≤548kV, the phase sequence is Correct, disconnect the first high-voltage 500kV circuit breaker 15, close the third high-voltage 500kV circuit breaker 29, check and confirm that the voltage indication at the end of the second 500kV line 27 is ≤548kV and the phase sequence is correct, disconnect the generator output circuit breaker 10, close the first high-voltage 500kV circuit breaker 15, close the generator output circuit breaker 10 again, check and confirm that the voltage indication at the end of the first 500kV line 18 and the second 500kV line 27 is ≤548kV and the phase sequence is correct;

[0090] In the step 5), the operator first disconnects the second 10kV power supply switch 4, and then closes the third 10kV power supply switch 6. The load of the 10kV power supply bus 5 is restored and powered by the hydro-generator 9. The operator checks and confirms that the voltage indication of the 10kV power supply bus 5 is stable, and the variation range is less than or equal to 3% of the rated voltage 10kV.

[0091] In the step 6), the operating personnel disconnect the third 10kV switch 6 for plant use, close the second 10kV switch 4 for plant use, close the excitation system and guide vanes of the hydro-generator 9, the hydro-generator 9 is in a shutdown state, the diesel generator 1 is shut down, and the first 10kV switch 2 for plant use, the second 10kV switch 4 for plant use, the generator output circuit breaker 10, the first high-voltage 500kV circuit breaker 15, and the third high-voltage 500kV circuit breaker 29 are disconnected in sequence, the overvoltage protection setting of the hydro-generator 9 is restored to 130V, the delay time is set to 5s, the tripping logic is restored, and the black start of the hydro-generator 9 and the step-up transformer 12 with the first 500kV line 18 or the second 500kV line 27 is completed.

[0092] The present invention accurately determines the technical difficulties existing in the black start process through self-excitation and overvoltage tests; utilizes the backup power supply as the second backup power supply of the diesel generator to prevent the diesel generator from starting failure; modifies the overvoltage setting of the black start generator to ensure the safety of the primary equipment involved in the black start; the excitation system and the synchronization system are respectively provided with a black start pressure plate and a single-side no-pressure closing pressure plate to avoid the risk of misoperation in manual operation; the excitation system adopts the automatic excitation AVR mode, modifies the low excitation limit to the generator PQ power curve, and makes the generator-transformer-line voltage after closing not exceed the allowable value; and the knife switch and the switch within the black start range are operated to the hot standby state.

[0093] The above is only a preferred embodiment of the patent of the present invention, and does not impose any limitation on the patent of the present invention. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A 500kV voltage level three-quarter connection hydropower station black start system, characterized in that: It comprises a diesel generator (1), a 10 kV busbar (5) for a plant, a hydro-generator (9), a first 500 kV line (18), a first reactor (20) and a second 500 kV line (27); The diesel generator (1) is connected to the 10kV power supply busbar (5) via a first 10kV power supply switch (2), a first 10kV power supply knife switch (3), and a second 10kV power supply switch (4) in sequence; The 10kV plant busbar (5) passes through the third 10kV plant switch (6) and the high-voltage plant transformer (7) in sequence; The grounding end of the hydro-generator (9) is grounded via a neutral point grounding knife switch (8), and the power generation end is connected in sequence via a generator outlet circuit breaker (10), a generator outlet knife switch (11), a step-up transformer (12) and a first high-voltage 500 kV knife switch (13); The second 500 kV line (27) is connected to the first 500 kV line (18) in sequence via an eighth high-voltage 500 kV knife switch (26), a ninth high-voltage 500 kV knife switch (28), a third high-voltage 500 kV circuit breaker (29), a tenth high-voltage 500 kV knife switch (30), a second high-voltage 500 kV knife switch (14), a first high-voltage 500 kV circuit breaker (15), a third high-voltage 500 kV knife switch (16), and a fourth high-voltage 500 kV knife switch (17); One end of the first reactor (20) is grounded via the second reactor (21), and the other end is connected to a common point where the fourth high-voltage 500kV knife switch (17) and the first 500kV line (18) are connected via a fifth high-voltage 500kV knife switch (19); A high-voltage plant transformer (7) T is connected to a common point where the generator outlet knife switch (11) and the step-up transformer (12) are connected; The first high-voltage 500 kV knife switch (13) T is connected to a common point where the second high-voltage 500 kV knife switch (14) and the tenth high-voltage 500 kV knife switch (30) are connected.

2. A 500kV voltage level three-quarter connection hydropower station black start system according to claim 1, characterized in that: It also includes a first 500 kV busbar (22), a second 500 kV busbar (34) and a backup power supply (35); The first 500kV busbar (22) is sequentially connected to a common point where the eighth high-voltage 500kV knife switch (26) and the ninth high-voltage 500kV knife switch (28) are connected, after being connected via a sixth high-voltage 500kV knife switch (23), a second high-voltage 500kV circuit breaker (24), and a seventh high-voltage 500kV knife switch (25); The second 500kV busbar (34) is sequentially connected to a common point where the third 500kV knife switch (16) and the fourth 500kV knife switch (17) are connected, after passing through a twelfth high-voltage 500kV knife switch (33), a fourth high-voltage 500kV circuit breaker (32), and an eleventh high-voltage 500kV knife switch (31); The backup power supply (35) is connected to the common point where the first plant 10kV switch (2) and the first plant 10kV knife switch (3) are connected after passing through the fourth plant 10kV switch (36); The diesel generator (1) serves as the first safety backup power supply for the black start of the hydro-generator (9), and the backup power supply (35) serves as the second safety backup power supply for the black start of the hydro-generator (9).

3. A 500kV voltage level three-quarter connection hydropower station black start system according to claim 2, characterized in that: When performing a black start self-excitation test on the hydro-generator (9), the step-up transformer (12) and the first 500kV line (18), the overvoltage protection setting value of the hydro-generator (9) is set to 115V, the delay time is set to 0s, and the tripping logic is modified to disconnect the generator output circuit breaker (10), disconnect the third plant 10kV switch (6), the third high-voltage 500kV circuit breaker (29) and the fourth high-voltage 500kV circuit breaker (32); adjust the The rotation speed of the hydro-generator (9) is 104.2 r / min; the neutral point grounding knife switch (8), the generator outlet circuit breaker (10), the generator outlet knife switch (11), the first high-voltage 500 kV knife switch (13), the second high-voltage 500 kV knife switch (14), the first high-voltage 500 kV circuit breaker (15), the third high-voltage 500 kV knife switch (16), the fourth high-voltage 500 kV knife switch (17) and the fifth high-voltage 500 kV knife switch (19) are closed.

4. A 500kV voltage level three-quarter connection hydropower station black start system according to claim 3, characterized in that: When performing a black start self-excitation test on the hydro-generator (9), the step-up transformer (12) and the second 500 kV line (27), the third plant-use 10 kV switch (6), the first high-voltage 500 kV circuit breaker (15) and the second high-voltage 500 kV circuit breaker (24) are disconnected; the rotation speed of the hydro-generator (9) is adjusted to 104.2 r / min; and the neutral point grounding knife switch (8), the generator outlet circuit breaker (10), the generator outlet knife switch (11), the first high-voltage 500 kV knife switch (13), the eighth high-voltage 500 kV knife switch (26), the ninth high-voltage 500 kV knife switch (28), the third high-voltage 500 kV circuit breaker (29) and the tenth high-voltage 500 kV knife switch (30) are closed.

5. A 500kV voltage level three-quarter connection hydropower station black start system according to claim 4, characterized in that: When performing a black start self-excitation test on the hydro-generator (9), the step-up transformer (12), the first 500 kV line (18) and the second 500 kV line (27), the third plant 10 kV switch (6), the second high-voltage 500 kV circuit breaker (24) and the fourth high-voltage 500 kV circuit breaker (32) are disconnected; the rotation speed of the hydro-generator (9) is adjusted to 104.2 r / min; the neutral point grounding knife switch (8), the generator outlet circuit breaker (10) and the generator outlet are closed. A knife switch (11), a first high-voltage 500 kV knife switch (13), a second high-voltage 500 kV knife switch (14), a first high-voltage 500 kV circuit breaker (15), a third high-voltage 500 kV knife switch (16), a fourth high-voltage 500 kV knife switch (17), a fifth high-voltage 500 kV knife switch (19), an eighth high-voltage 500 kV knife switch (26), a ninth high-voltage 500 kV knife switch (28), a third high-voltage 500 kV circuit breaker (29) and a tenth high-voltage 500 kV knife switch (30).

6. A 500kV voltage level three-quarter connection hydropower station black start system according to claim 5, characterized in that: When performing an overvoltage test on the diesel generator (1), the high-voltage plant transformer (7), the step-up transformer (12), and the first 500 kV line (18), the fourth plant 10 kV switch (36), the generator outlet circuit breaker (10), the third high-voltage 500 kV circuit breaker (29), and the fourth high-voltage 500 kV circuit breaker (32) are disconnected; the diesel generator (1) is started and the voltage is built up to the rated voltage of 10 kV; the first plant 10 kV switch (2), the first plant 10 kV knife switch (3), the second plant 10 kV switch (4), the third plant 10 kV switch (6), the first high-voltage 500 kV knife switch (13), the second high-voltage 500 kV knife switch (14), the first high-voltage 500 kV circuit breaker (15), the third high-voltage 500 kV knife switch (16), the fourth high-voltage 500 kV knife switch (17), and the fifth high-voltage 500 kV knife switch (19) are closed.

7. A 500kV voltage level three-quarter connection hydropower station black start system according to claim 6, characterized in that: When conducting an overvoltage test on the diesel generator (1), the high-voltage plant transformer (7), the step-up transformer (12), and the second 500 kV line (27), the fourth plant 10 kV switch (36), the generator outlet circuit breaker (10), the first high-voltage 500 kV circuit breaker (15), and the second high-voltage 500 kV circuit breaker (24) are disconnected; the diesel generator (1) is started and the voltage is built up to the rated voltage of 10 kV; the first plant 10 kV switch (2), the first plant 10 kV knife switch (3), the second plant 10 kV switch (4), the third plant 10 kV switch (6), the first high-voltage 500 kV knife switch (13), the eighth high-voltage 500 kV knife switch (26), the ninth high-voltage 500 kV knife switch (28), the third high-voltage 500 kV circuit breaker (29), and the tenth high-voltage 500 kV knife switch (30) are closed.

8. A 500kV voltage level three-quarter connection hydropower station black start system according to claim 7, characterized in that: When performing an overvoltage test on the diesel generator (1), the high-voltage plant transformer (7), the step-up transformer (12), the first 500 kV line (18) and the second 500 kV line (27), the fourth plant 10 kV switch (36), the generator outlet circuit breaker (10), the second high-voltage 500 kV circuit breaker (24) and the fourth high-voltage 500 kV circuit breaker (32) are disconnected; the diesel generator (1) is started and the voltage is built up to the rated voltage of 10 kV; the first plant 10 kV switch (2) and the first plant 10 kV knife switch (3) are closed. , a second 10 kV switch for plant use (4), a third 10 kV switch for plant use (6), a first high-voltage 500 kV knife switch (13), a second high-voltage 500 kV knife switch (14), a first high-voltage 500 kV circuit breaker (15), a third high-voltage 500 kV knife switch (16), a fourth high-voltage 500 kV knife switch (17), a fifth high-voltage 500 kV knife switch (19), an eighth high-voltage 500 kV knife switch (26), a ninth high-voltage 500 kV knife switch (28), a third high-voltage 500 kV circuit breaker (29), and a tenth high-voltage 500 kV knife switch (30).

9. A 500kV voltage level three-quarter connection hydropower station black start system according to claim 8, characterized in that: When the hydro-generator (9) and the step-up transformer (12) perform a black start charging test on the first 500 kV line (18) and the second 500 kV line (27), the fourth plant 10 kV switch (36), the third plant 10 kV switch (6), the second high-voltage 500 kV circuit breaker (24), and the fourth high-voltage 500 kV circuit breaker (32) are disconnected, and the neutral point grounding knife switch (8), the generator outlet circuit breaker (10), and the generator outlet knife switch (11) are closed. ), a first high-voltage 500 kV knife switch (13), a second high-voltage 500 kV knife switch (14), a third high-voltage 500 kV knife switch (16), a fourth high-voltage 500 kV knife switch (17), a fifth high-voltage 500 kV knife switch (19), an eighth high-voltage 500 kV knife switch (26), a ninth high-voltage 500 kV knife switch (28), a tenth high-voltage 500 kV knife switch (30), a first high-voltage 500 kV circuit breaker (15) and a third high-voltage 500 kV circuit breaker (29).

10. A black start method for a 500kV voltage level three-quarters connection hydropower station, characterized in that: The system according to any one of claims 1 to 9 comprises the following steps: 1) Carry out preparation work for the black start test, and proceed to step 2) after all preliminary preparation work is completed; 2) carrying out a self-excitation test of the hydro-generator (9) and the step-up transformer (12) on the first 500 kV line (18) or the second 500 kV line (27), and judging whether the self-excitation phenomenon occurs according to whether the voltage and current signals of the hydro-generator (9), the first 500 kV line (18) and the second 500 kV line (27) oscillate; if there is no self-excitation phenomenon, proceeding to step 3); if there is a self-excitation phenomenon, proceeding to step 6); 3) using the diesel generator (1) to carry out an overvoltage test on the first 500 kV line (18) or the second 500 kV line (27), calculating the ratio n of the voltage between the end and the head of the first 500 kV line (18) or the second 500 kV line (27), dividing the maximum allowable operating voltage of the end 548 kV by n to determine the high-voltage side target value of the step-up transformer (12) during black start, and then proceeding to step 4); 4) starting the diesel generator (1) to supply power to the load of the 10 kV busbar (5) for the factory, carrying out a black start charging test of the hydro-generator (9) and the step-up transformer (12) with the first 500 kV line (18) or the second 500 kV line (27), checking and confirming that the terminal voltage indication and phase sequence of the first 500 kV line (18) or the second 500 kV line (27) are correct, and proceeding to step 5); 5) The load of the 10 kV busbar (5) for the power plant is restored and the power is supplied by the hydro-generator (9). Check and confirm that the voltage indication of the 10 kV busbar (5) for the power plant is stable and the variation range is less than or equal to 3% of the rated voltage 10 kV, and then proceed to step 6); 6) The black start of the hydro-generator (9) and the step-up transformer (12) with the first 500 kV line (18) or the second 500 kV line (27) is completed.

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