A black start system and method for a hydropower station with a dual-voltage-level connection

Abstract

A black start system and method for a hydropower station with a dual voltage level connection, including the first hydrogenerator, a three-winding main transformer, a first 500 kV circuit breaker, a second 220 kV circuit breaker, a first 220 kV line, a 500 kV circuit breaker, a second 500 kV line, a fourth 500 kV circuit breaker, a third 500 kV line, a high-voltage station service transformer, and a 10 kV station service incoming switch; by closing all switches and disconnecting switches on the black start path, only the circuit breakers supplying power to the lines are kept open, using the self-energy storage of the hydrogenerator to open the guide vanes to start the unit. When the hydrogenerator reaches a constant speed at the rated speed, the control mode of the excitation system is switched to the automatic mode, enabling the hydrogenerator to build up voltage to the rated voltage with the three-winding main transformer, promptly restoring the working power supply of the station service system, and successively realizing the power transmission of the first 220 kV line, the second 500 kV line, and the third 500 kV line, improving the black start capacity of the power grid and ensuring the safety of the power plant and the grid in response to extreme situations.

Description

Technical Field

[0001] The invention belongs to the technical field of hydroelectric black start, and particularly relates to a hydroelectric power station black start system and method with a double-voltage-level connection. Background Art

[0002] With the change of the global environment, extreme natural disasters have occurred frequently in recent years, having a major impact on the normal life of human beings. As electricity is the most basic requirement in fields such as industry, agriculture, and residential life, how to ensure a stable, reliable, and safe power supply has always been the goal that power workers in all countries strive for. From a global perspective, the power grid construction makes every effort to build a strong power grid and formulates various assessment systems, aiming to reduce the probability of power outages. Black start just serves as a strong guarantee after a power grid security accident. Whether it is the entire power grid or a local power grid, after the power grid loses power, capable units should restore power transmission in the first time to relieve the power grid pressure. For this reason, local power grids have specifically formulated policies to incorporate black start into the policies of auxiliary services. Power plants with black start capabilities will receive economic compensation every year, especially for units that can help the power grid black start in time after the power grid loses power, and the reward is even greater. The existing well-known black start technologies have the following problems: (1) The voltage level of the outgoing line is single, usually one voltage level and one wiring structure, resulting in a small restoration range during black start. Especially for large units, the black start power supply capacity is weakened; (2) The two units do not adopt an extended unit connection. If the self-storage capacity of one unit is insufficient, in the case of startup failure, the other unit cannot be started quickly, prolonging the black start time. At the same time, the two units cannot achieve a fast standby conversion function; (3) During black start, the excitation uses a manual method to charge the line empty, resulting in an automatic voltage rise when the line is put into operation, bringing potential safety hazards to various electrical equipment. Summary of the Invention

[0003] Aiming at the problems existing in the prior art, the invention provides a hydroelectric power station black start system with a double-voltage-level connection, which can quickly send the power supply to the power grids with two voltage levels and structures when the power grid loses power, expand the restoration range, and ensure the safety of the power grid.

[0004] The invention is realized through the following technical solutions:

[0005] A hydroelectric power station black start system with a double-voltage-level connection includes a first hydrogenerator, a first 220 kV line, a seventh 500 kV disconnecting switch, a second 500 kV line, a tenth 500 kV disconnecting switch, a third 500 kV line, a high-voltage station service transformer, a 10 kV station service incoming switch, and a 10 kV busbar;

[0006] One end of the first hydro-generator is connected to the first neutral point grounding switch. The power generation end is successively connected to the first 220 kV line through the first outlet circuit breaker, the first outlet switch, the second branch of the three-winding main transformer, the first 500 kV switch, the second 500 kV switch, the first 500 kV circuit breaker, the third 500 kV switch, the second 500 kV bus, the fourth 500 kV switch, the second 500 kV circuit breaker, the fifth 500 kV switch, the sixth 500 kV switch, the tie transformer, the first 220 kV switch, the first 220 kV circuit breaker, the second 220 kV switch, the first 220 kV bus, the third 220 kV switch, the second 220 kV circuit breaker, and the fourth 220 kV switch;

[0007] One end of the seventh 500 kV switch is T-connected to the common point between the first 500 kV switch and the second 500 kV switch, and the other end is successively connected to the second 500 kV line through the third 500 kV circuit breaker, the eighth 500 kV switch, and the ninth 500 kV switch;

[0008] One end of the tenth 500 kV switch is connected to the second 500 kV bus, and the other end is successively connected to the third 500 kV line through the fourth 500 kV circuit breaker, the eleventh 500 kV switch, and the twelfth 500 kV switch;

[0009] One end of the high-voltage station service transformer is connected to the first branch of the three-winding main transformer, and the other end is connected to the 10 kV bus through the 10 kV station service incoming switch.

[0010] Preferably, it further includes a second hydro-generator, a thirteenth 500 kV switch, a first 500 kV bus, a fifth 220 kV switch, a second 220 kV bus, and a sixth 220 kV switch;

[0011] One end of the second hydro-generator is connected to the second neutral point grounding switch, and the power generation end is successively connected to the first branch of the three-winding main transformer through the second outlet circuit breaker and the second outlet switch;

[0012] One end of the thirteenth 500 kV switch is T-connected to the common point between the eighth 500 kV switch and the ninth 500 kV switch, and the other end is successively connected to the first 500 kV bus through the fifth 500 kV circuit breaker and the fourteenth 500 kV switch;

[0013] One end of the fifth 220 kV switch is connected to the common point between the first 220 kV circuit breaker and the second 220 kV switch, and the other end is connected to the second 220 kV bus;

[0014] One end of the sixth 220 kV disconnect switch is connected to the second 220 kV bus, and the other end is connected to the common point between the third 220 kV disconnect switch and the second 220 kV circuit breaker.

[0015] Further, before the first hydro-generator and the three-winding main transformer perform black start with the first 220 kV line, the second 500 kV line, and the third 500 kV line, the first neutral point earthing switch, the first outlet switch, the first 500 kV disconnect switch, the second 500 kV disconnect switch, the first 500 kV circuit breaker, the third 500 kV disconnect switch, the fourth 500 kV disconnect switch, the second 500 kV circuit breaker, the fifth 500 kV disconnect switch, the first 220 kV disconnect switch, the first 220 kV circuit breaker, the second 220 kV disconnect switch, the third 220 kV disconnect switch, the fourth 220 kV disconnect switch, the seventh 500 kV disconnect switch, the eighth 500 kV disconnect switch, the ninth 500 kV disconnect switch, the tenth 500 kV disconnect switch, the eleventh 500 kV disconnect switch, the twelfth 500 kV disconnect switch, the second neutral point earthing switch, and the second outlet switch are all in the closed state; the first outlet circuit breaker, the second 220 kV circuit breaker, the third 500 kV circuit breaker, the fourth 500 kV circuit breaker, the 10 kV auxiliary power incoming switch, the second outlet circuit breaker, the thirteenth 500 kV disconnect switch, the fifth 500 kV circuit breaker, the fourteenth 500 kV disconnect switch, the fifth 220 kV disconnect switch, and the sixth 220 kV disconnect switch are all in the open state.

[0016] Further, when the first hydro-generator and the three-winding main transformer charge the first 220 kV line, the first outlet circuit breaker, the 10 kV auxiliary power incoming switch, and the second 220 kV circuit breaker are in the closed state.

[0017] Further, when the first hydro-generator and the three-winding main transformer charge the second 500 kV line, the third 500 kV circuit breaker is in the closed state.

[0018] Further, when the first hydro-generator and the three-winding main transformer charge the third 500 kV line, the fourth 500 kV circuit breaker is in the closed state.

[0019] Further, when the first hydro-generator cannot reach a fixed speed or build voltage, disconnect the first outlet circuit breaker, adjust the speed of the second hydro-generator to a fixed value, build voltage to the rated state, and then close the second outlet circuit breaker.

[0020] A black start method for a hydropower station with a double-voltage-level connection includes the following steps:

[0021] 1) Transfer the 10 kV auxiliary power incoming switch to cold standby and proceed to step 2);

[0022] 2) The second hydrogenerator is put into cold reserve, and proceed to step 3);

[0023] 3) Disable the primary frequency regulation function of the first hydrogenerator, and proceed to step 4);

[0024] 4) Disable the reclosing of the first 220 kV line, the second 500 kV line, and the third 500 kV line, and proceed to step 5);

[0025] 5) Disconnect the first outlet breaker, the second 220 kV breaker, the third 500 kV breaker, the fourth 500 kV breaker, the 10 kV station service incoming switch, the second outlet breaker, the fifth 500 kV breaker, the thirteenth 500 kV disconnecting switch, the fourteenth 500 kV disconnecting switch, the fifth 220 kV disconnecting switch, and the sixth 220 kV disconnecting switch in sequence, and proceed to step 6);

[0026] 6) Close the first neutral point earthing switch, the first outlet disconnecting switch, the first 500 kV disconnecting switch, the second 500 kV disconnecting switch, the third 500 kV disconnecting switch, the fourth 500 kV disconnecting switch, the fifth 500 kV disconnecting switch, the first 220 kV disconnecting switch, the second 220 kV disconnecting switch, the third 220 kV disconnecting switch, the fourth 220 kV disconnecting switch, the seventh 500 kV disconnecting switch, the eighth 500 kV disconnecting switch, the ninth 500 kV disconnecting switch, the tenth 500 kV disconnecting switch, the eleventh 500 kV disconnecting switch, the twelfth 500 kV disconnecting switch, the second neutral point earthing switch, the second outlet disconnecting switch, the first 500 kV breaker, the second 500 kV breaker, and the first 220 kV breaker in sequence, and proceed to step 7);

[0027] 7) Exhaust the air bag of the first hydrogenerator, check and confirm that the air bag pressure gauge indicates 0, and proceed to step 8);

[0028] 8) Disable the braking brake of the first hydrogenerator, and proceed to step 9);

[0029] 9) Pull out the servomotor lock of the first hydrogenerator, and proceed to step 10);

[0030] 10) Set the speed of the first hydrogenerator to 200 r / min, and proceed to step 11);

[0031] 11) Boost the voltage of the first hydrogenerator with a three-winding main transformer to 16.46 kV in AVR mode, and proceed to step 12);

[0032] 12) Close the 10 kV station service incoming switch, check and confirm that the 10 kV bus is at 10 kV, and resume the first hydrogenerator to operate with the 10 kV bus, and proceed to step 13);

[0033] 13) Close the second 220 kV circuit breaker to charge the first 220 kV line. Check and confirm that the voltage of the first 220 kV line is 220 kV, and proceed to step 14).

[0034] 14) Close the third 500 kV circuit breaker to charge the second 500 kV line. Check and confirm that the voltage of the second 500 kV line is 527 kV, and proceed to step 15).

[0035] 15) Close the fourth 500 kV circuit breaker to charge the third 500 kV line. Check and confirm that the voltage of the third 500 kV line is 527 kV, and proceed to step 16).

[0036] 16) The black start of the first hydro-generator and the three-winding main transformer with the first 220 kV line, the second 500 kV line, and the third 500 kV line is completed.

[0037] Furthermore, when boosting the voltage with AVR in step 11), the under-excitation limit function of the first hydro-generator is withdrawn.

[0038] Furthermore, when the black start in step 16) is completed, disconnect the second 220 kV circuit breaker, the third 500 kV circuit breaker, and the fourth 500 kV circuit breaker in sequence, and stop the operation of the first hydro-generator with a speed of 0.

[0039] In the present invention, all switches and disconnectors on the black start path are closed, and only the circuit breakers for powering the lines are left in the open state. The hydro-generator uses its self-energy storage to open the guide vanes to start the unit. When the hydro-generator reaches the rated speed, the control mode of the excitation system is switched to the automatic mode, enabling the hydro-generator to build up voltage to the rated voltage with the three-winding main transformer, and promptly restoring the working power supply of the plant system. The power transmission of the first 220 kV line, the second 500 kV line, and the third 500 kV line is realized in sequence, providing a new black start system and method with multiple voltage levels and multiple wiring structures for the power grid, enhancing the black start ability of the power grid, and ensuring the safety of the plant and the grid in the face of extreme situations.

[0040] Furthermore, after the successful black start of the hydro-generator in the present invention, the power is sent out by using a total of three lines of 220 kV and 500 kV, and two wiring structure modes of 3 / 2 and double busbars, expanding the black start power supply and restoration scope, reducing the impact of large power outages on various places, and enhancing the power supply capacity of the hydro-generator set.

[0041] Furthermore, the two units of the present invention adopt an extended unit connection and are mutually standby during black start. When one unit fails to start due to a fault, the other unit can achieve rapid start with fewer operations, reducing the risk of black start failure, saving black start time, and enabling rapid power transmission from the black start unit in case of a fault.

[0042] Furthermore, the excitation of the present invention adopts an automatic control mode, directly building up the voltage of the hydrogenerator and the three-winding transformer to the rated value, avoiding the problem of long zero-start voltage build-up operation time in the manual mode. At the same time, when the line is put into operation, automatic field weakening is used to counteract the magnetizing effect of capacitive current, maintain the rated voltage, prevent voltage rise problems, and ensure the safety of black start equipment. Brief Description of the Drawings

[0043] Figure 1 It is a schematic diagram of the black start principle of the present invention.

[0044] Figure 2 It is a schematic diagram of the principle before black start of the present invention.

[0045] Figure 3 It is a schematic diagram of the charging principle of the first hydrogenerator and the three-winding main transformer of the present invention for the second 500 kV line.

[0046] Figure 4 It is a schematic diagram of the charging principle of the first hydrogenerator and the three-winding main transformer of the present invention for the third 500 kV line.

[0047] Figure 5 It is a schematic diagram of the charging principle of the first hydrogenerator and the three-winding main transformer of the present invention for the third 500 kV line.

[0048] In the figure: First neutral point earthing switch 1; First hydrogenerator 2; First outgoing circuit breaker 3; First outgoing disconnecting switch 4; Three-winding main transformer 5; First 500 kV disconnecting switch 6; Second 500 kV disconnecting switch 7; First 500 kV circuit breaker 8; Third 500 kV disconnecting switch 9; Second 500 kV busbar 10; Fourth 500 kV disconnecting switch 11; Second 500 kV circuit breaker 12; Fifth 500 kV disconnecting switch 13; Sixth 500 kV disconnecting switch 14; Tie transformer 15; First 220 kV disconnecting switch 16; First 220 kV circuit breaker 17; Second 220 kV disconnecting switch 18; First 220 kV busbar 19; Third 220 kV disconnecting switch 20; Second 220 kV circuit breaker 21; Fourth 220 kV disconnecting switch 22; First 220 kV line 23; Seventh 500 kV disconnecting switch 24; Third 500 kV circuit breaker 25; Eighth 500 kV disconnecting switch 26; Ninth 500 kV disconnecting switch 27; Second 500 kV line 28; Tenth 500 kV disconnecting switch 29; Fourth 500 kV circuit breaker 30; Eleventh 500 kV disconnecting switch 31; Twelfth 500 kV disconnecting switch 32; Third 500 kV line 33; High-voltage station service transformer 34; 10 kV station service incoming switch 35; 10 kV busbar 36; Second neutral point earthing switch 37; Second hydrogenerator 38; Second outgoing circuit breaker 39; Second outgoing disconnecting switch 40; Thirteenth 500 kV disconnecting switch 41; Fifth 500 kV circuit breaker 42; Fourteenth 500 kV disconnecting switch 43; First 500 kV busbar 44; Fifth 220 kV disconnecting switch 45; Second 220 kV busbar 46; Sixth 220 kV disconnecting switch 47. Detailed implementation manners

[0049] The present invention will be further described in detail below in conjunction with specific embodiments, which are explanations rather than limitations of the present invention.

[0050] The present invention can solve the black start problems of two-thirds, double-busbar and extended unit connection hydropower stations with voltage levels of 220 kV and 500 kV, especially the problems of single voltage level of outgoing lines, no standby for black start units, and the problem of voltage rise during line charging with manual excitation voltage mode in black start.

[0051] A black start system for a hydropower station with a dual voltage level connection according to the present invention, as Figure 1As shown, it includes the first neutral point earthing switch 1, the first hydro-generator 2, the first outgoing circuit breaker 3, the first outgoing disconnecting switch 4, the three-winding main transformer 5, the first 500 kV disconnecting switch 6, the second 500 kV disconnecting switch 7, the first 500 kV circuit breaker 8, the third 500 kV disconnecting switch 9, the second 500 kV busbar 10, the fourth 500 kV disconnecting switch 11, the second 500 kV circuit breaker 12, the fifth 500 kV disconnecting switch 13, the sixth 500 kV disconnecting switch 14, the linking transformer 15, the first 220 kV disconnecting switch 16, the first 220 kV circuit breaker 17, the second 220 kV disconnecting switch 18, the first 220 kV busbar 19, the third 220 kV disconnecting switch 20, the second 220 kV circuit breaker 21, the fourth 220 kV disconnecting switch 22, the first 220 kV line 23, the seventh 500 kV disconnecting switch 24, the third 500 kV circuit breaker 25, the eighth 500 kV disconnecting switch 26, the ninth 500 kV disconnecting switch 27, the second 500 kV line 28, the tenth 500 kV disconnecting switch 29, the fourth 500 kV circuit breaker 30, the eleventh 500 kV disconnecting switch 31, the twelfth 500 kV disconnecting switch 32, the third 500 kV line 33, the high-voltage auxiliary transformer 34, the 10 kV auxiliary incoming switch 35 and the 10 kV busbar 36; wherein, one end of the first neutral point earthing switch 1 is connected to the [description missing in the original], and the other end is successively connected to the first 220 kV line 23 via the first hydro-generator 2, the first outgoing circuit breaker 3, the first outgoing disconnecting switch 4, the second branch of the three-winding main transformer 5, the first 500 kV disconnecting switch 6, the second 500 kV disconnecting switch 7, the first 500 kV circuit breaker 8, the third 500 kV disconnecting switch 9, the second 500 kV busbar 10, the fourth 500 kV disconnecting switch 11, the second 500 kV circuit breaker 12, the fifth 500 kV disconnecting switch 13, the sixth 500 kV disconnecting switch 14, the linking transformer 15, the first 220 kV disconnecting switch 16, the first 220 kV circuit breaker 17, the second 220 kV disconnecting switch 18, the first 220 kV busbar 19, the third 220 kV disconnecting switch 20, the second 220 kV circuit breaker 21, the fourth 220 kV disconnecting switch 22; one end of the seventh 500 kV disconnecting switch 24 is T-connected to the common point between the first 500 kV disconnecting switch 6 and the second 500 kV disconnecting switch 7, and the other end is successively connected to the second 500 kV line 28 via the third 500 kV circuit breaker 25, the eighth 500 kV disconnecting switch 26, the ninth 500 kV disconnecting switch 27; one end of the tenth 500 kV disconnecting switch 29 is connected to the second 500 kV busbar 10, and the other end is successively connected to the third 500 kV line 33 via the fourth 500 kV circuit breaker 30, the eleventh 500 kV disconnecting switch 31, the twelfth 500 kV disconnecting switch 32; one end of the high-voltage auxiliary transformer 34 is connected to the first branch of the three-winding main transformer 5, and the other end is connected to the 10 kV busbar 36 via the 10 kV auxiliary incoming switch 35 and the 10 kV busbar 36.

[0052] It should be noted that there seems to be some inaccuracies or missing information in the original text, especially in the description of the connection of the first neutral point earthing switch 1 where part of the connection description is missing. This translation is based on the existing text as accurately as possible.In this embodiment, it further includes a second neutral point earthing switch 37, a second hydro-generator 38, a second outgoing circuit breaker 39, a second outgoing switch 40, a thirteenth 500 kV switch 41, a fifth 500 kV circuit breaker 42, a fourteenth 500 kV switch 43, a first 500 kV busbar 44, a fifth 220 kV switch 45, a second 220 kV busbar 46 and a sixth 220 kV switch 47. One end of the second neutral point earthing switch 37 is grounded, and the other end is sequentially connected to the first branch of the three-winding main transformer 5 via the second hydro-generator 38, the second outgoing circuit breaker 39 and the second outgoing switch 40. One end of the thirteenth 500 kV switch 41 is T-connected to the common point between the eighth 500 kV switch 26 and the ninth 500 kV switch 27, and the other end is sequentially connected to the first 500 kV busbar 44 via the fifth 500 kV circuit breaker 42 and the fourteenth 500 kV switch 43. One end of the fifth 220 kV switch 45 is connected to the common point between the first 220 kV circuit breaker 17 and the second 220 kV switch 18, and the other end is connected to the second 220 kV busbar 46. One end of the sixth 220 kV switch 47 is connected to the second 220 kV busbar 46, and the other end is connected to the common point between the third 220 kV switch 20 and the second 220 kV circuit breaker 21.

[0053] In this embodiment, the parameters of the first hydro-generator 2 are as follows in the table:

[0054]

[0055] In this embodiment, the parameters of the three-winding main transformer 5 are as follows in the table:

[0056]

[0057] In this embodiment, the parameters of the connecting transformer 15 are as follows in the table:

[0058] Model SUB-MRT Rated capacity 750 / 750 / 30 MVA Rated voltage 550 / 242 / 38.5 kV Rated frequency 50 Hz Rated current 787 / 1789 / 450A Connection group Ynaod11 (Autotransformer) Manufacturer Mitsubishi Electric Corporation, Japan Impedance HV-MV 12.36％ Impedance MV-LV 98.00％ Impedance HV-LV 109.5％

[0059] In this embodiment, the parameters of the high-voltage station service transformer 34 are as follows in the table:

[0060]

[0061] Such as Figure 2As shown in the figure, before the black start of the first hydro-generator 2 and the three-winding main transformer 5 with the first 220 kV line 23, the second 500 kV line 28, and the third 500 kV line 33, the first neutral grounding switch 1, the first outlet switch 4, the first 500 kV switch 6, the second 500 kV switch 7, the first 500 kV circuit breaker 8, the third 500 kV switch 9, the fourth 500 kV switch 11, the second 500 kV circuit breaker 12, the fifth 500 kV switch 13, the first 220 kV switch 16, the first 220 kV circuit breaker 17, the second 220 kV switch 18, the third 220 kV switch 20, the fourth 220 kV switch 22, the seventh 500 kV switch 24, the eighth 500 kV switch 26, the ninth 500 kV switch 27, the tenth 500 kV switch 29, the eleventh 500 kV switch 31, the twelfth 500 kV switch 32, the second neutral grounding switch 37, and the second outlet switch 40 are all in the closed state; the first outlet circuit breaker 3, the second 220 kV circuit breaker 21, the third 500 kV circuit breaker 25, the fourth 500 kV circuit breaker 30, the 10 kV auxiliary power incoming switch 35, the second outlet circuit breaker 39, the thirteenth 500 kV switch 41, the fifth 500 kV circuit breaker 42, the fourteenth 500 kV switch 43, the fifth 220 kV switch 45, and the sixth 220 kV switch 47 are all in the open state.

[0062] As Figure 3 shown in the figure, when the first hydro-generator 2 and the three-winding main transformer 5 charge the first 220 kV line 23, the first outlet circuit breaker 3, the 10 kV auxiliary power incoming switch 35, and the second 220 kV circuit breaker 21 are in the closed state. The terminal voltage of the first hydro-generator 2 is 16.46 kV, the terminal current is 3.81 kA, the excitation voltage is 50 V, the excitation current is 365 A. The voltage of the 10 kV bus 36 is 10 kV, and the voltage of the high-voltage side of the three-winding main transformer 5 is 527 kV.

[0063] As Figure 4 shown in the figure, when the first hydro-generator 2 and the three-winding main transformer 5 charge the second 500 kV line 28, the third 500 kV circuit breaker 25 is in the closed state.

[0064] As Figure 5 shown in the figure, when the first hydro-generator 2 and the three-winding main transformer 5 charge the third 500 kV line 33, the fourth 500 kV circuit breaker 30 is in the closed state.

[0065] In this embodiment, when the first hydro-generator 2 cannot reach a fixed speed or build voltage, the first outlet circuit breaker 3 is disconnected, the second hydro-generator 38 is adjusted to reach a fixed speed, and the voltage is built up to the rated state, and then the second outlet circuit breaker 39 is closed.

[0066] A black start method for a hydropower station with a dual-voltage-level connection, comprising the following steps:

[0067] 1) Transfer the 10kV auxiliary power incoming switch to cold standby, and proceed to step 2);

[0068] 2) Transfer the second hydro-generator to cold standby, and proceed to step 3);

[0069] 3) Withdraw the primary frequency regulation function of the first hydro-generator, and proceed to step 4);

[0070] 4) Withdraw the reclosing of the first 220kV line, the second 500kV line, and the third 500kV line, and proceed to step 5);

[0071] 5) Disconnect the first outlet breaker, the second 220kV breaker, the third 500kV breaker, the fourth 500kV breaker, the 10kV auxiliary power incoming switch, the second outlet breaker, the fifth 500kV breaker, the thirteenth 500kV disconnecting switch, the fourteenth 500kV disconnecting switch, the fifth 220kV disconnecting switch, and the sixth 220kV disconnecting switch in sequence, and proceed to step 6);

[0072] 6) Close the first neutral point grounding switch, the first outlet disconnecting switch, the first 500kV disconnecting switch, the second 500kV disconnecting switch, the third 500kV disconnecting switch, the fourth 500kV disconnecting switch, the fifth 500kV disconnecting switch, the first 220kV disconnecting switch, the second 220kV disconnecting switch, the third 220kV disconnecting switch, the fourth 220kV disconnecting switch, the seventh 500kV disconnecting switch, the eighth 500kV disconnecting switch, the ninth 500kV disconnecting switch, the tenth 500kV disconnecting switch, the eleventh 500kV disconnecting switch, the twelfth 500kV disconnecting switch, the second neutral point grounding switch, the second outlet disconnecting switch, the first 500kV breaker, the second 500kV breaker, and the first 220kV breaker in sequence, and proceed to step 7);

[0073] 7) Exhaust the air duct of the first hydro-generator, check and confirm that the air duct pressure gauge indicates 0, and proceed to step 8);

[0074] 8) Withdraw the brake of the first hydro-generator, and proceed to step 9);

[0075] 9) Pull out the servomotor lock of the first hydro-generator, and proceed to step 10);

[0076] 10) Set the speed of the first hydro-generator to 200 r / min, and proceed to step 11);

[0077] 11) The first hydro-generator 2 is stepped up to 16.46 kV in AVR mode with a three-winding main transformer 5, and step 12) is entered;

[0078] 12) Close the 10 kV auxiliary power incoming switch 35, check and confirm that the 10 kV busbar 36 is at 10 kV, and resume the first hydro-generator 2 to operate with the 10 kV busbar 36, and step 13) is entered;

[0079] 13) Close the second 220 kV circuit breaker 21 to charge the first 220 kV line 23, check and confirm that the voltage of the first 220 kV line 23 is 220 kV, and step 14) is entered;

[0080] 14) Close the third 500 kV circuit breaker 25 to charge the second 500 kV line 28, check and confirm that the voltage of the second 500 kV line 28 is 527 kV, and step 15) is entered;

[0081] 15) Close the fourth 500 kV circuit breaker 30 to charge the third 500 kV line 33, check and confirm that the voltage of the third 500 kV line 33 is 527 kV, and step 16) is entered;

[0082] 16) The black start of the first hydro-generator 2 and the three-winding main transformer 5 with the first 220 kV line 23, the second 500 kV line 28, and the third 500 kV line 33 is completed.

[0083] In this embodiment, when boosting the voltage in AVR in step 11), the under-excitation limit function of the first hydro-generator 2 is withdrawn; when the black start in step 16) is completed, the second 220 kV circuit breaker 21, the third 500 kV circuit breaker 25, and the fourth 500 kV circuit breaker 30 are disconnected in sequence, and the operation of the first hydro-generator 2 is stopped, and the rotational speed is 0.

[0084] A black start system and method for a hydropower station with a dual voltage level connection, including the first hydrogenerator, three-winding main transformer, first 500 kV circuit breaker, second 220 kV circuit breaker, first 220 kV line, 500 kV circuit breaker, second 500 kV line, fourth 500 kV circuit breaker, third 500 kV line, high-voltage station service transformer and 10 kV station service incoming switch; by closing all switches and disconnecting switches on the black start path, only the circuit breaker supplying power to the line is kept open, using the self-energy storage of the hydrogenerator to open the guide vane to start the unit. When the hydrogenerator reaches the rated speed, the control mode of the excitation system is switched to the automatic mode, enabling the hydrogenerator to build voltage to the rated voltage with the three-winding main transformer, and timely restoring the working power supply of the station service system. The power supply of the first 220 kV line, the second 500 kV line, and the third 500 kV line is realized in sequence, providing a new black start system and method with multiple voltage levels and multiple wiring structures for the power grid, enhancing the black start ability of the power grid, and ensuring the safety of the power plant and the grid in response to extreme situations.

[0085] The above are only preferred embodiments of the present invention patent, and do not impose any limitations on the present invention patent. Any simple modifications, changes, and equivalent structural changes made to the above embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A black start system for a hydropower station with a double voltage level connection, characterized in that It includes a first hydrogenerator (2), a first 220 kV line (23), a seventh 500 kV disconnecting switch (24), a second 500 kV line (28), a tenth 500 kV disconnecting switch (29), a third 500 kV line (33), a high-voltage station service transformer (34), a 10 kV station service incoming switch (35), and a 10 kV busbar (36); One end of the first hydrogenerator (2) is connected to a first neutral point earthing disconnecting switch (1), and the generating end is successively connected to the first 220 kV line (23) via a first outlet circuit breaker (3), a first outlet disconnecting switch (4), the second branch of a three-winding main transformer (5), a first 500 kV disconnecting switch (6), a second 500 kV disconnecting switch (7), a first 500 kV circuit breaker (8), a third 500 kV disconnecting switch (9), a second 500 kV busbar (10), a fourth 500 kV disconnecting switch (11), a second 500 kV circuit breaker (12), a fifth 500 kV disconnecting switch (13), a sixth 500 kV disconnecting switch (14), a linking transformer (15), a first 220 kV disconnecting switch (16), a first 220 kV circuit breaker (17), a second 220 kV disconnecting switch (18), a first 220 kV busbar (19), a third 220 kV disconnecting switch (20), a second 220 kV circuit breaker (21), and a fourth 220 kV disconnecting switch (22); One end of the seventh 500 kV disconnecting switch (24) is T-connected to the common point between the first 500 kV disconnecting switch (6) and the second 500 kV disconnecting switch (7), and the other end is successively connected to the second 500 kV line (28) via a third 500 kV circuit breaker (25), an eighth 500 kV disconnecting switch (26), and a ninth 500 kV disconnecting switch (27); One end of the tenth 500 kV disconnecting switch (29) is connected to the second 500 kV busbar (10), and the other end is successively connected to the third 500 kV line (33) via a fourth 500 kV circuit breaker (30), an eleventh 500 kV disconnecting switch (31), and a twelfth 500 kV disconnecting switch (32); One end of the high-voltage station service transformer (34) is connected to the first branch of the three-winding main transformer (5), and the other end is connected via a 10 kV station service incoming switch (35) and a 10 kV busbar (36).

2. The black start system of a hydropower station with a double voltage level connection according to claim 1, wherein It further includes a second hydrogenerator (38), a thirteenth 500 kV disconnecting switch (41), a first 500 kV busbar (44), a fifth 220 kV disconnecting switch (45), a second 220 kV busbar (46), and a sixth 220 kV disconnecting switch (47); One end of the second hydrogenerator (38) is connected to a second neutral point earthing disconnecting switch (37), and the generating end is successively connected to the first branch of the three-winding main transformer (5) via a second outlet circuit breaker (39) and a second outlet disconnecting switch (40); One end of the thirteenth 500 kV disconnect switch (41) is tee-connected to the common point between the eighth 500 kV disconnect switch (26) and the ninth 500 kV disconnect switch (27), and the other end is connected to the first 500 kV busbar (44) successively through the fifth 500 kV circuit breaker (42) and the fourteenth 500 kV disconnect switch (43). One end of the fifth 220 kV disconnect switch (45) is connected to the common point between the first 220 kV circuit breaker (17) and the second 220 kV disconnect switch (18), and the other end is connected to the second 220 kV busbar (46). One end of the sixth 220 kV disconnect switch (47) is connected to the second 220 kV busbar (46), and the other end is connected to the common point between the third 220 kV disconnect switch (20) and the second 220 kV circuit breaker (21).

3. A black start system for a hydropower station with a double voltage level connection according to claim 2, characterized in that, Before the first hydrogenerator (2) and the three-winding main transformer (5) perform black start with the first 220 kV line (23), the second 500 kV line (28), and the third 500 kV line (33), the first neutral grounding disconnect switch (1), the first outlet disconnect switch (4), the first 500 kV disconnect switch (6), the second 500 kV disconnect switch (7), the first 500 kV circuit breaker (8), the third 500 kV disconnect switch (9), the fourth 500 kV disconnect switch (11), the second 500 kV circuit breaker (12), the fifth 500 kV disconnect switch (13), the first 220 kV disconnect switch (16), the first 220 kV circuit breaker (17), the second 220 kV disconnect switch (18), the third 220 kV disconnect switch (20), the fourth 220 kV disconnect switch (22), the seventh 500 kV disconnect switch (24), the eighth 500 kV disconnect switch (26), the ninth 500 kV disconnect switch (27), the tenth 500 kV disconnect switch (29), the eleventh 500 kV disconnect switch (31), the twelfth 500 kV disconnect switch (32), the second neutral grounding disconnect switch (37), and the second outlet disconnect switch (40) are all in the closed state; the first outlet circuit breaker (3), the second 220 kV circuit breaker (21), the third 500 kV circuit breaker (25), the fourth 500 kV circuit breaker (30), the 10 kV auxiliary power incoming switch (35), the second outlet circuit breaker (39), the thirteenth 500 kV disconnect switch (41), the fifth 500 kV circuit breaker (42), the fourteenth 500 kV disconnect switch (43), the fifth 220 kV disconnect switch (45), and the sixth 220 kV disconnect switch (47) are all in the open state.

4. A black start system for a hydropower station with a dual voltage level connection, as claimed in claim 3, wherein When the first hydrogenerator (2) and the three-winding main transformer (5) charge the first 220 kV line (23), the first outlet circuit breaker (3), the 10 kV auxiliary power incoming switch (35), and the second 220 kV circuit breaker (21) are in the closed state.

5. A black start system for a hydropower station with a dual voltage level connection according to claim 4, characterized in that, When the first hydrogenerator (2) and the three-winding main transformer (5) charge the second 500 kV line (28), the third 500 kV circuit breaker (25) is in the closed state.

6. A black start system for a hydropower station with a double voltage level connection according to claim 5, characterized in that, When the first hydrogenerator (2) and the three-winding main transformer (5) charge the third 500 kV line (33), the fourth 500 kV circuit breaker (30) is in the closed state.

7. A black start system for a hydropower station with a dual voltage level connection, as claimed in claim 6, wherein When the first hydrogenerator (2) cannot reach a fixed speed or build voltage, disconnect the first outlet circuit breaker (3), adjust the speed of the second hydrogenerator (38) to a fixed value, build voltage to the rated state, and close the second outlet circuit breaker (39).

8. A black start method for a hydropower station with a double-voltage-level connection, characterized in that, The system according to any one of claims 2-7 includes the following steps: 1) Transfer the 10 kV auxiliary power incoming switch (35) to cold standby and proceed to step 2); 2) Transfer the second hydrogenerator (38) to cold standby and proceed to step 3); 3) Withdraw the primary frequency regulation function of the first hydrogenerator (2) and proceed to step 4); 4) Withdraw the reclosing of the first 220 kV line (23), the second 500 kV line (28), and the third 500 kV line (33) and proceed to step 5); 5) Disconnect the first outlet circuit breaker (3), the second 220 kV circuit breaker (21), the third 500 kV circuit breaker (25), the fourth 500 kV circuit breaker (30), the 10 kV auxiliary power incoming switch (35), the second outlet circuit breaker (39), the fifth 500 kV circuit breaker (42), the thirteenth 500 kV disconnecting switch (41), the fourteenth 500 kV disconnecting switch (43), the fifth 220 kV disconnecting switch (45), and the sixth 220 kV disconnecting switch (47) in sequence and proceed to step 6); 6) Close the first neutral point grounding disconnecting switch (1), the first outlet disconnecting switch (4), the first 500 kV disconnecting switch (6), the second 500 kV disconnecting switch (7), the third 500 kV disconnecting switch (9), the fourth 500 kV disconnecting switch (11), the fifth 500 kV disconnecting switch (13), the first 220 kV disconnecting switch (16), the second 220 kV disconnecting switch (18), the third 220 kV disconnecting switch (20), the fourth 220 kV disconnecting switch (22), the seventh 500 kV disconnecting switch (24), the eighth 500 kV disconnecting switch (26), the ninth 500 kV disconnecting switch (27), the tenth 500 kV disconnecting switch (29), the eleventh 500 kV disconnecting switch (31), the twelfth 500 kV disconnecting switch (32), the second neutral point grounding disconnecting switch (37), the second outlet disconnecting switch (40), the first 500 kV circuit breaker (8), the second 500 kV circuit breaker (12), and the first 220 kV circuit breaker (17) in sequence and proceed to step 7); 7) Exhaust the air duct of the first hydrogenerator (2), check and confirm that the air duct pressure gauge indicates 0, and proceed to step 8); 8) Withdraw the braking brake of the first hydrogenerator (2) and proceed to step 9); 9) Pull out the servomotor locking pin of the first hydrogenerator (2) and proceed to step 10); 10) Set the speed of the first hydrogenerator (2) to 200 r / min and proceed to step 11); 11) The first hydrogenerator (2) drives the three-winding main transformer (5) to boost the voltage to 16.46 kV in AVR mode and proceed to step 12); 12) Close the 10 kV auxiliary power incoming switch (35), check and confirm that the voltage of the 10 kV busbar (36) is 10 kV, resume the operation of the first hydro-generator (2) with the 10 kV busbar (36), and proceed to step 13). 13) Close the second 220 kV circuit breaker (21), charge the first 220 kV line (23), check and confirm that the voltage of the first 220 kV line (23) is 220 kV, and proceed to step 14). 14) Close the third 500 kV circuit breaker (25), charge the second 500 kV line (28), check and confirm that the voltage of the second 500 kV line (28) is 527 kV, and proceed to step 15). 15) Close the fourth 500 kV circuit breaker (30), charge the third 500 kV line (33), check and confirm that the voltage of the third 500 kV line (33) is 527 kV, and proceed to step 16). 16) The black start of the first hydro-generator (2) and the three-winding main transformer (5) with the first 220 kV line (23), the second 500 kV line (28), and the third 500 kV line (33) is completed.

9. A black start method for a hydropower station with a dual-voltage-level connection according to claim 8, characterized in that, When boosting the voltage with AVR in step 11), the under-excitation limiting function of the first hydro-generator (2) is withdrawn.

10. A black start method for a hydropower station with a dual voltage level connection according to claim 8, characterized in that, When the black start in step 16) is completed, disconnect the second 220 kV circuit breaker (21), the third 500 kV circuit breaker (25), and the fourth 500 kV circuit breaker (30) in sequence, and stop the operation of the first hydro-generator (2) with the speed being 0.

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