A black start system and method for a thermal power plant with small hydropower

Abstract

The invention discloses a black start system and method for a thermal power plant with small hydropower, comprising a first hydro-turbine generator, a second hydro-turbine generator, a third hydro-turbine generator, a fourth hydro-turbine generator, a first main transformer, a second main transformer, a first step-down transformer, a second step-down transformer, a first three-winding plant transformer, a second three-winding plant transformer, a first double-winding plant transformer, a second double-winding plant transformer, and a 35kV sending T-connected line; after the sending line of the thermal power unit loses power, the small hydropower in the thermal power plant is quickly started, the small hydropower supplies power to one section of the plant power system of the thermal power unit, the other section of the bus is connected to the small hydropower bus through the three-winding transformer, the two sections of the plant bus of the thermal power plant are restored to power, and the power supply of the power failure system is quickly restored; when the sending line of the thermal power unit operates normally, the small hydropower can assist the thermal power unit in participating in AGC frequency modulation or supply power to the power grid through the T-connected line.

Description

Technical Field

[0001] The invention belongs to the technical field of black start of a thermal power plant with small hydropower, and in particular relates to a black start system and method of a thermal power plant with small hydropower. Background Art

[0002] At present, my country's black start is mainly based on hydropower and gas turbines. Thermal power does not have the ability to start in black due to too many limiting factors. The main reason is that there are many auxiliary machines in thermal power. A large power supply is needed to drive the auxiliary machines to run during black start. At the same time, after the power grid loses power, the auxiliary machines of the thermal power units are used for a period of time, and the temperature of the boilers and steam turbines gradually transitions to a cold state. When all complex processes are fault-free, it takes several hours or more than a day to restart. Therefore, thermal power has always been a key technology that restricts its black start due to its special operating conditions and physical characteristics. The condition for thermal power to have the ability to start in black is that after the power grid loses power, all auxiliary machines can switch to a power supply with a larger capacity, that is, when the boilers and steam turbines are in an extremely hot state, the power can be quickly delivered in a short time. At present, thermal power urgently needs a power supply that can store energy, is controllable, and has a capacity greater than the auxiliary machines used in the plant to achieve black start.

[0003] At present, the black start technology of thermal power plants has the following main problems: (1) In addition to the backup power supply, the thermal power plant has no small hydropower with the capacity to start and control the machine, which restricts its black start capability; (2) There is no relevant literature on the use of small hydropower to assist thermal power plant units; (3) There are currently no cases or reports of small hydropower assisting thermal power units in AGC frequency regulation; (4) There is currently no relevant technology for using three-winding transformers to cross-power the power supply to start the unit when small hydropower assists thermal power units in black start. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a black start system and method for a thermal power plant with small hydropower, which can enable the thermal power units to have black start capability and provide safety guarantee for the power grid.

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

[0006] A black start system of a thermal power plant with small hydropower comprises a first hydro-generator, a second hydro-generator, a third hydro-generator, a fourth hydro-generator, a fourth 6kV switch, a first 6kV bus, a second 6kV bus, a second main transformer, a third 35kV switch, a first 35kV bus, a second 35kV bus, a sixth 35kV switch, a third 6kV bus, a fourth 6kV bus, a ninth 6kV switch, a tenth 6kV switch, a first three-winding plant transformer and a first 20kV circuit breaker;

[0007] The first hydro-generator is connected to the first 6kV busbar via the first 6kV switch; the second hydro-generator is connected to the first 6kV busbar via the third 6kV switch; the third hydro-generator is connected to the second 6kV busbar via the fifth 6kV switch; the fourth hydro-generator is connected to the second 6kV busbar via the seventh 6kV switch;

[0008] Two ends of the fourth 6kV switch are connected to the first 6kV bus and the second 6kV bus respectively;

[0009] One end of the second main transformer is connected to the second 6kV bus, and the other end is connected to the second 35kV bus via a second 35kV switch;

[0010] One end of the third 35kV switch is connected to the second 35kV bus, and the other end is connected to the first 6kV bus via the first 35kV bus, the fifth 35kV switch, the first 35kV switch, and the first main transformer in sequence;

[0011] One end of the sixth 35kV switch is connected to the second 35kV bus, and the other end is connected to the third 6kV bus via the third 35kV knife switch, the first step-down transformer, and the eighth 6kV switch in sequence;

[0012] One end of the first 20kV circuit breaker is connected to the first generator end, and the other end is connected to the high-voltage side of the first three-winding plant transformer. The low-voltage side A branch of the first three-winding plant transformer is connected to the third 6kV bus via the ninth 6kV switch, and the low-voltage side B branch of the first three-winding plant transformer is connected to the fourth 6kV bus via the tenth 6kV switch.

[0013] Preferably, it also includes a second 6kV switch, a sixth 6kV switch, a fourth 35kV switch, a seventh 35kV switch, a fifth 6kV bus, a sixth 6kV bus, a second three-winding plant transformer, a second 20kV circuit breaker, a first 400V bus, a second 400V bus, a third 400V switch and a 35kV sending T-connection line;

[0014] One end of the second 6kV switch is connected to the first 6kV bus, and the other end is connected to the first 400V bus via the first double-winding plant transformer and the first 400V switch in sequence;

[0015] One end of the sixth 6kV switch is connected to the second 6kV bus, and the other end is connected to the second 400V bus via the second double-winding plant transformer and the second 400V switch in sequence;

[0016] One end of the third 400V switch is connected to the first 400V bus, and the other end is connected to the second 400V bus;

[0017] One end of the fourth 35kV switch is connected to the common point of the first 35kV switch and the fifth 35kV switch, and the other end is connected to the 35kV output T-connected line via the first 35kV switch;

[0018] One end of the seventh 35kV switch is connected to the common point of the first 35kV switch and the fifth 35kV switch, and the other end is connected to the fifth 6kV busbar via the second 35kV knife switch, the second step-down transformer, and the eleventh 6kV switch in sequence;

[0019] One end of the second 20kV circuit breaker is connected to the second generator end, and the other end is connected to the high voltage side of the second three-winding plant transformer. The low voltage side A branch of the second three-winding plant transformer is connected to the fifth 6kV bus via the twelfth 6kV switch, and the low voltage side B branch of the second three-winding plant transformer is connected to the sixth 6kV bus via the thirteenth 6kV switch.

[0020] Further, when the first hydro-turbine generator, the second hydro-turbine generator, the third hydro-turbine generator and the fourth hydro-turbine generator all provide black start power for the load of the first three-winding plant transformer or participate in AGC frequency modulation, the first 6kV switch, the second 6kV switch, the third 6kV switch, the fifth 6kV switch, the sixth 6kV switch, the seventh 6kV switch, the first 35kV switch, the second 35kV switch, the third 35kV switch, the fifth 35kV switch, the sixth 35kV switch, the second 35kV knife switch, the third 35kV knife switch, the eighth 6kV switch, the ninth 6kV switch, the tenth 6kV switch, the first 400V switch and the second 400V switch are all in a closed state, and the third 400V switch, the fourth 35kV switch, the seventh 35kV switch, the eleventh 6kV switch and the first 20kV circuit breaker are all in an open state.

[0021] Furthermore, when the first hydro-turbine generator, the second hydro-turbine generator, the third hydro-turbine generator and the fourth hydro-turbine generator all provide black start power for the second third-winding plant transformer load or participate in AGC frequency modulation, the seventh 35kV switch, the second 35kV knife switch, the eleventh 6kV switch, the twelfth 6kV switch and the thirteenth 6kV switch are all in a closed state, and the sixth 35kV switch and the third 35kV knife switch are all in an open state.

[0022] Preferably, when the first hydro-generator and the second hydro-generator provide black start power for the second three-winding plant transformer load or participate in AGC frequency modulation, when the third hydro-generator and the fourth hydro-generator provide black start power for the first three-winding plant transformer load or participate in AGC frequency modulation, the first 6kV switch, the second 6kV switch, the third 6kV switch, the fifth 6kV switch, the sixth 6kV switch, the seventh 6kV switch, the first 35kV switch, the second 35kV switch, the sixth 35kV switch The fourth 6kV switch, the third 35kV switch, the second 35kV knife switch, the third 35kV knife switch, the eighth 6kV switch, the ninth 6kV switch, the tenth 6kV switch, the eleventh 6kV switch, the twelfth 6kV switch, the thirteenth 6kV switch, the first 400V switch, and the second 400V switch are all in a closed state, and the fourth 6kV switch, the third 35kV switch, the fourth 35kV switch, the fifth 35kV switch, the first 20kV circuit breaker, and the second 20kV circuit breaker are all in an open state.

[0023] Preferably, when the first three-winding plant transformer and the second three-winding plant transformer do not perform black start, the first hydro-generator, the second hydro-generator, the third hydro-generator and the fourth hydro-generator are all powered by the 35kV sending T-connected line, and the first 6kV switch, the second 6kV switch, the third 6kV switch, the fifth 6kV switch, the sixth 6kV switch, the seventh 6kV switch, the first 35kV switch, the second 35kV switch, the third 35kV switch and the fourth 35kV switch are powered by the 35kV sending T-connected line. The fourth 6kV switch, the sixth 35kV switch, the seventh 35kV switch, the second 35kV knife switch, the third 35kV knife switch, the eighth 6kV switch and the eleventh 6kV switch are all in the open state.

[0024] Furthermore, when the first hydro-turbine generator, the second hydro-turbine generator, the third hydro-turbine generator and the fourth hydro-turbine generator all assist the first three-winding plant transformer or the second three-winding plant transformer in participating in AGC frequency modulation, the grid frequency is stabilized by adjusting the power of the first hydro-turbine generator, the second hydro-turbine generator, the third hydro-turbine generator and the fourth hydro-turbine generator and tracking the AGC target instructions.

[0025] A black start method for a thermal power plant with small hydropower comprises the following steps:

[0026] 1) Disconnect the fourth 6kV switch, the fourth 35kV switch, the seventh 35kV switch, the second 35kV switch, and the first 20kV circuit breaker in sequence, and proceed to step 2);

[0027] 2) Close the first 6kV switch, the second 6kV switch, the third 6kV switch, the fifth 6kV switch, the sixth 6kV switch; the seventh 6kV switch, the first 35kV switch, the second 35kV switch, the third 35kV switch, the fifth 35kV switch, the sixth 35kV switch, the ninth 6kV switch, and the tenth 6kV switch in sequence, and proceed to step 3);

[0028] 3) adjusting the voltage of the first hydro-generator, the second hydro-generator, the third hydro-generator and the fourth hydro-generator to the rated voltage of 6.3 kV, and proceeding to step 4);

[0029] 4) Close the first 400V switch and the second 400V switch, and proceed to step 5);

[0030] 5) The eighth 6kV switch is closed, and the third 6kV busbar and the fourth 6kV busbar loads are powered by the first hydro-generator, the second hydro-generator, the third hydro-generator, and the fourth hydro-generator, and the process proceeds to step 6);

[0031] 6) The first generator connected to the first three-winding plant transformer is ignited, rushed, set at a constant speed, and built up voltage. After the first generator builds up voltage to the rated voltage, the grid-connected switch is closed to charge the line and provide power to the grid, and then step 7 is entered;

[0032] 7) The black start of the first generator connected to the first three-winding plant transformer is completed.

[0033] Preferably, in the step 3), the voltage of the first 35kV bus and the second 35kV bus is 35kV; in the step 4), the voltage of the first 400V bus and the second 400V bus is 400V; in the step 5), the voltage of the third 6kV bus and the fourth 6kV bus is 6.3kV.

[0034] Compared with the prior art, the present invention has the following beneficial technical effects:

[0035] After the power outage of the thermal power unit transmission line, the present invention quickly starts up through the small hydropower in the thermal power plant. The small hydropower supplies power to one section of the busbar of the thermal power unit's power supply system, and the other section of the busbar is connected to the small hydropower busbar through a three-winding transformer to supply power. Both sections of the thermal power plant's power supply busbars are restored to power, and the unit is started, speeded, and pressure built up according to the extremely hot state program, and power supply to the power-lost system is quickly restored; when the thermal power unit transmission line is operating normally, the small hydropower can assist the thermal power unit in participating in AGC frequency modulation or supply power to the power grid through a T-connected line; the present invention provides a new type of thermal power black start system and method, so that the thermal power unit has black start capability, improves the safety and stability of the power grid, can participate in the AGC frequency modulation of the power grid to increase the operating economic benefits of the thermal power unit, and flexibly switches the operating mode of the small hydropower according to different application scenarios to meet the daily safety, frequency modulation, and power supply needs of the power grid.

[0036] Furthermore, during black start, the small hydropower of the present invention has flexible wiring, can supply power to the plant systems of one or two thermal power units, realize extremely hot start of the thermal power units and send out power, provide the power grid with large-capacity and reliable black start power, and reduce the pressure of power outage of the power grid.

[0037] Furthermore, any section of the busbar on the low-voltage side of the three-winding transformer of the present invention is powered by small hydropower, and the other section is powered by the three-winding transformer, which can reduce the investment in primary equipment, simplify system wiring, and enhance operational flexibility.

[0038] Furthermore, when the power grid is operating normally, the small hydropower of the present invention can participate in the AGC frequency regulation of one or two thermal power plants, stabilize the frequency of the power grid, give play to the natural advantages of thermal power units with small hydropower, assist the thermal power units in following and matching the AGC instructions, and improve the frequency regulation performance and economic benefits of the thermal power units; the present invention does not require the thermal power units to add additional electrochemical energy storage, thereby improving the frequency regulation safety of the thermal power units.

[0039] Furthermore, the small hydropower of the present invention can also send power to the power grid through a T-connected line, thereby reducing line investment costs and providing the power grid with high-quality, cost-effective green energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a system principle diagram of the present invention.

[0041] Figure 2 The first hydro-turbine generator, the second hydro-turbine generator, the third hydro-turbine generator and the fourth hydro-turbine generator of the present invention all provide black start power for the first three-winding plant transformer load or participate in the AGC frequency modulation principle diagram.

[0042] Figure 3The first hydro-turbine generator, the second hydro-turbine generator, the third hydro-turbine generator and the fourth hydro-turbine generator of the present invention all provide black start power for the load of the second three-winding plant transformer or participate in the AGC frequency modulation principle diagram.

[0043] Figure 4 The first hydro-generator and the second hydro-generator of the present invention provide black start power for the second three-winding plant transformer load or participate in AGC frequency modulation, and the third hydro-generator and the fourth hydro-generator provide black start power for the first three-winding plant transformer load or participate in AGC frequency modulation principle diagram.

[0044] Figure 5 This is a schematic diagram of power supply principle of 35kV sending T-connected lines for the first hydro-turbine generator, the second hydro-turbine generator, the third hydro-turbine generator and the fourth hydro-turbine generator of the present invention.

[0045] In the figure: the first hydro-generator 1; the second hydro-generator 2; the third hydro-generator 3; the fourth hydro-generator 4; the first 6kV switch 5; the second 6kV switch 6; the third 6kV switch 7; the fourth 6kV switch 8; the fifth 6kV switch 9; the sixth 6kV switch 10; the seventh 6kV switch 11; the first 6kV bus 12; the second 6kV bus 13; the first main transformer 14; the second main transformer 15; the first 35kV switch 16; the second 35kV switch 17; the third 35kV switch 18; the fourth 35kV switch 19; the first 35kV bus 20; the second 35kV bus 21; the fifth 35kV switch 22; the sixth 35kV switch 23; the seventh 35kV switch 24; the first 35kV knife switch 25; the second 35kV knife switch 26; the third 35kV knife switch 27; the fourth 35kV knife switch 28; the first 35kV knife switch 29; the second 35kV knife switch 30; the third 35kV knife switch 31; the first 35kV knife switch 32; the second 35kV knife switch 33; the third 35kV knife switch 34; the first 35kV knife switch 35; the second 35kV knife switch 36; the third 35kV knife switch 37; the third 35kV knife switch 38; the fourth 35kV knife switch 39; the first 35kV knife switch 40; the second 35kV knife switch 41; the first 35kV knife switch 42; the second 35kV knife switch 43; the third 35k Gate 27; eighth 6kV switch 28; third 6kV bus 29; fourth 6kV bus 30; ninth 6kV switch 31; tenth 6kV switch 32; first step-down transformer 33; first three-winding plant transformer 34; first 20kV circuit breaker 35; eleventh 6kV switch 36; fifth 6kV bus 37; sixth 6kV bus 38; second step-down transformer 39; twelfth 6kV switch 40; thirteenth 6kV switch 41; second three-winding plant transformer 42; second 20kV circuit breaker 43; first double-winding plant transformer 44; second double-winding plant transformer 45; first 400V switch 46; second 400V switch 47; first 400V bus 48; second 400V bus 49; third 400V switch 50; 35kV sending T-connected line 51. DETAILED DESCRIPTION

[0046] 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.

[0047] The present invention can solve the black start and frequency modulation problems of thermal power units, utilize the transformer crossing power supply mode, reduce the primary equipment investment, enable the thermal power units to have black start capability, give play to the natural advantages of small hydropower units, participate in AGC frequency modulation or external power supply of thermal power units, and improve the operation flexibility of thermal power units.

[0048] The present invention discloses a black start system and method for a thermal power plant with small hydropower, comprising a first hydro-turbine generator, a second hydro-turbine generator, a third hydro-turbine generator, a fourth hydro-turbine generator, a first main transformer, a second main transformer, a first step-down transformer, a second step-down transformer, a first three-winding plant transformer, a second three-winding plant transformer, a first double-winding plant transformer, a second double-winding plant transformer, and a 35kV sending T-connected line; after the sending line of the thermal power unit loses power, the present invention quickly starts the thermal power plant through the small hydropower in the thermal power plant, the small hydropower supplies power to one section of the busbar of the thermal power unit plant power system, and the other section of the busbar is connected to the small hydropower busbar. The line is powered by a three-winding transformer, and the two sections of the plant busbars of the thermal power plant are restored to power supply. The units are started, set speed, and build pressure according to the extremely hot state procedure, and power supply to the power-lost system is quickly restored. When the transmission line of the thermal power unit is operating normally, small hydropower can assist the thermal power unit in participating in AGC frequency regulation or supply power to the power grid through T-connected lines. A new type of thermal power black start system and method is provided to enable the thermal power unit to have black start capability, improve the safety and stability of the power grid, participate in the AGC frequency regulation of the power grid to increase the operating economic benefits of the thermal power unit, and flexibly switch the operating mode of small hydropower for different application scenarios to meet the daily safety, frequency regulation, and power supply needs of the power grid.

[0049] like Figure 1As shown, the present invention provides a black start system for a thermal power plant with small hydropower, comprising a first hydro-generator 1, a second hydro-generator 2, a third hydro-generator 3, a fourth hydro-generator 4, a first 6kV switch 5, a third 6kV switch 7, a fourth 6kV switch 8, a fifth 6kV switch 9, a seventh 6kV switch 11, a first 6kV bus 12, a second 6kV bus 13, a first main transformer 14, a second main transformer 15, a first 35kV switch 16, a second 35kV switch 17, a third 35kV switch 18, a first 35kV bus 20, a second 35kV bus 21, a fifth 35kV switch 22, sixth 35kV switch 23, third 35kV knife switch 27, eighth 6kV switch 28, third 6kV bus 29, fourth 6kV bus 30, ninth 6kV switch 31, tenth 6kV switch 32, first step-down transformer 33, first three-winding plant transformer 34 and first 20kV circuit breaker 35; wherein, the first hydro-generator 1 is connected to the first 6kV bus 12 via the first 6kV switch 5, the second hydro-generator 2 is connected to the first 6kV bus 12 via the third 6kV switch 7, the third hydro-generator 3 is connected to the second 6kV bus 12 via the fifth 6kV switch 9, The fourth hydro-generator 4 is connected to the second 6kV bus 13 via the seventh 6kV switch 11, one end of the second main transformer 15 is connected to the second 6kV bus 13, and the other end is connected to the second 35kV bus 21 via the second 35kV switch 17, one end of the third 35kV switch 18 is connected to the second 35kV bus 21, and the other end is connected to the first 6kV bus 12 via the first 35kV bus 20, the fifth 35kV switch 22, the first 35kV switch 16, and the first main transformer 14 in sequence, and the sixth 35kV switch 23 is connected to the second 35kV bus 21. One end is connected to the second 35kV bus 21, and the other end is connected to the third 6kV bus 29 via the third 35kV knife switch 27, the first step-down transformer 33, and the eighth 6kV switch 28 in sequence. One end of the first 20kV circuit breaker 35 is connected to the first generator end, and the other end is connected to the high-voltage side of the first three-winding plant transformer 34. The low-voltage side A branch of the first three-winding plant transformer 34 is connected to the third 6kV bus 29 via the ninth 6kV switch 31, and the low-voltage side B branch of the first three-winding plant transformer 34 is connected to the fourth 6kV bus 30 via the tenth 6kV switch 32. 。

[0050] In this embodiment, the second 6kV switch 6, the sixth 6kV switch 10, the fourth 35kV switch 19, the seventh 35kV switch 24, the first 35kV knife switch 25, the second 35kV knife switch 26, the eleventh 6kV switch 36, the fifth 6kV bus 37, the sixth 6kV bus 38, the second step-down transformer 39, the twelfth 6kV switch 40, the thirteenth 6kV switch 41, the second three-winding plant transformer 42, the second 20kV circuit breaker 43, the first double-winding plant transformer 44, the second double-winding plant transformer 45, the first 400 V switch 46, second 400V switch 47, first 400V bus 48, second 400V bus 49, third 400V switch 50 and 35kV sending T-connection line 51; wherein, one end of the second 6kV switch 6 is connected to the first 6kV bus 12, and the other end is connected to the first 400V bus 48 via the first double-winding plant transformer 44 and the first 400V switch 46 in sequence; one end of the sixth 6kV switch 10 is connected to the second 6kV bus 13, and the other end is connected to the second double-winding plant transformer 45, the second 400V The switch 47 is connected to the second 400V bus 49, the third 400V switch 50 is connected to the first 400V bus 48 at one end, and connected to the second 400V bus 49 at the other end; the fourth 35kV switch 19 is connected to the common point of the first 35kV switch 16 and the fifth 35kV switch 22 at one end, and connected to the 35kV output T-connection line 51 via the first 35kV knife switch 25 at the other end; the seventh 35kV switch 24 is connected to the common point of the first 35kV switch 16 and the fifth 35kV switch 22 at one end, and connected to the 35kV output T-connection line 51 via the first 35kV knife switch 25 at the other end; The second end is connected to the fifth 6kV bus 37 via the second 35kV knife switch 26, the second step-down transformer 39, and the eleventh 6kV switch 36 in sequence; one end of the second 20kV circuit breaker 43 is connected to the second generator end, and the other end is connected to the high-voltage side of the second three-winding plant transformer 42; the low-voltage side A branch of the second three-winding plant transformer 42 is connected to the fifth 6kV bus 37 via the twelfth 6kV switch 40; the low-voltage side B branch of the second three-winding plant transformer 42 is connected to the sixth 6kV bus 38 via the thirteenth 6kV switch 41.

[0051] In this embodiment, the first hydro-generator 1, the second hydro-generator 2, the third hydro-generator 3, and the fourth hydro-generator 4 have a rated capacity of 5625 kVA, a rated speed of 214.5 r / min, a rated excitation voltage of 126 V, a rated power of 4500 kW, and a rated excitation current of 343 A.

[0052] In this embodiment, the rated capacity of the first double-winding plant transformer 44 and the second double-winding plant transformer is 315kVA, and the connection group label is DY11; the rated capacity of the first main transformer 14 and the second main transformer 15 is 12500kVA, and the connection group label is Ynd11.

[0053] like Figure 2 As shown, when the first hydro-generator 1, the second hydro-generator 2, the third hydro-generator 3, and the fourth hydro-generator 4 all provide black start power for the first three-winding plant transformer 34 load or participate in AGC frequency modulation, the first 6kV switch 5, the second 6kV switch 6, the third 6kV switch 7, the fifth 6kV switch 9, the sixth 6kV switch 10, the seventh 6kV switch 11, the first 35kV switch 16, the second 35kV switch 17, the third 35kV switch 18, the fifth 35kV switch 22, the sixth 35kV switch 23, the second 35kV knife switch 26, the third 35kV knife switch 27, the eighth 6kV switch 28, the ninth 6kV switch 31, the tenth 6kV switch 32, the first 400V switch 46, and the second 400V switch 47 are all in a closed state. The third 400V switch 50, the fourth 35kV switch 19, the seventh 35kV switch 24, the eleventh 6kV switch 36, and the first 20kV circuit breaker 35 are all in the disconnected state; the rated voltage of the first hydro-generator 1, the second hydro-generator 2, the third hydro-generator 3, and the fourth hydro-generator 4 is 6.3kV, the transformation ratio of the first main transformer 14 and the second main transformer 15 is 6.3kV / 35kV, the transformation ratio of the first step-down transformer 33 and the second step-down transformer 39 is 35kV / 6.3kV, the transformation ratio of the first three-winding plant transformer 34 and the second three-winding plant transformer 42 is 20kV / 6.3kV / 6.3kV, and the transformation ratio of the first double-winding plant transformer 44 and the second double-winding plant transformer 45 is 6.3kV / 0.4kV.

[0054] like Figure 3 As shown, when the first hydro-generator 1, the second hydro-generator 2, the third hydro-generator 3, and the fourth hydro-generator 4 all provide black start power for the load of the second third-winding plant transformer 42 or participate in AGC frequency modulation, the seventh 35kV switch 24, the second 35kV knife switch 26, the eleventh 6kV switch 36, the twelfth 6kV switch 40, and the thirteenth 6kV switch 41 are all in a closed state, and the sixth 35kV switch 23 and the third 35kV knife switch 27 are all in an open state.

[0055] like Figure 4As shown, when the first hydro-generator 1 and the second hydro-generator 2 provide black start power for the second three-winding plant transformer 42 load or participate in AGC frequency modulation, when the third hydro-generator 3 and the fourth hydro-generator 4 provide black start power for the first three-winding plant transformer 34 load or participate in AGC frequency modulation, the first 6kV switch 5, the second 6kV switch 6, the third 6kV switch 7, the fifth 6kV switch 9, the sixth 6kV switch 10, the seventh 6kV switch 11, the first 35kV switch 16, the second 35kV switch 17, the sixth 35kV switch 23, The seventh 35kV switch 24, the second 35kV knife switch 26, the third 35kV knife switch 27, the eighth 6kV switch 28, the ninth 6kV switch 31, the tenth 6kV switch 32, the eleventh 6kV switch 36, the twelfth 6kV switch 40, the thirteenth 6kV switch 41, the first 400V switch 46, and the second 400V switch 47 are all in the closed state, and the fourth 6kV switch 8, the third 35kV switch 18, the fourth 35kV switch 19, the fifth 35kV switch 22, the first 20kV circuit breaker 35, and the second 20kV circuit breaker 43 are all in the open state.

[0056] like Figure 5 As shown, when the first three-winding plant transformer 34 and the second three-winding plant transformer 42 do not perform black start, the first hydro-generator 1, the second hydro-generator 2, the third hydro-generator 3, and the fourth hydro-generator 4 are all powered by the 35kV sending T-connection line 51, and the first 6kV switch 5, the second 6kV switch 6, the third 6kV switch 7, the fifth 6kV switch 9, the sixth 6kV switch 10, the seventh 6kV switch 11, the first 35kV switch 16, the second 35kV switch 17, the third 35kV switch 18, the fourth 35kV switch 19, ... The fifth 35kV switch 22, the first 35kV knife switch 25, the ninth 6kV switch 31, the tenth 6kV switch 32, the first 20kV circuit breaker 35, the twelfth 6kV switch 40, the thirteenth 6kV switch 41, the second 20kV circuit breaker 43, the first 400V switch 46, and the second 400V switch 47 are all in a closed state, and the fourth 6kV switch 8, the sixth 35kV switch 23, the seventh 35kV switch 24, the second 35kV knife switch 26, the third 35kV knife switch 27, the eighth 6kV switch 28, and the eleventh 6kV switch 36 are all in an open state.

[0057] In this embodiment, when the first hydro-turbine generator 1, the second hydro-turbine generator 2, the third hydro-turbine generator 3, and the fourth hydro-turbine generator 4 all assist the first three-winding plant transformer 34 or the second three-winding plant transformer 42 in participating in AGC frequency modulation, the power grid frequency is stabilized by adjusting the power of the first hydro-turbine generator 1, the second hydro-turbine generator 2, the third hydro-turbine generator 3, and the fourth hydro-turbine generator 4 and tracking the AGC target instructions.

[0058] A black start method for a thermal power plant with small hydropower comprises the following steps:

[0059] 1) disconnect the fourth 6kV switch 8, the fourth 35kV switch 19, the seventh 35kV switch 24, the second 35kV switch 26, and the first 20kV circuit breaker 35 in sequence, and proceed to step 2);

[0060] 2) Sequentially close the first 6kV switch 5, the second 6kV switch 6, the third 6kV switch 7, the fifth 6kV switch 9, the sixth 6kV switch 10; the seventh 6kV switch 11, the first 35kV switch 16, the second 35kV switch 17, the third 35kV switch 18, the fifth 35kV switch 22, the sixth 35kV switch 23, the ninth 6kV switch 31, the tenth 6kV switch 32, and proceed to step 3);

[0061] 3) adjusting the voltage of the first hydro-generator 1, the second hydro-generator 2, the third hydro-generator 3, and the fourth hydro-generator 4 to the rated voltage of 6.3 kV, and proceeding to step 4);

[0062] 4) Close the first 400V switch 46 and the second 400V switch 47, and proceed to step 5);

[0063] 5) The eighth 6kV switch 28 is closed, and the third 6kV bus 29 and the fourth 6kV bus 30 are powered by the first hydro-generator 1, the second hydro-generator 2, the third hydro-generator 3, and the fourth hydro-generator 4, and the process proceeds to step 6);

[0064] 6) The first generator connected to the first three-winding plant transformer 34 is ignited, rushed, kept at a constant speed, and built up voltage. After the first generator builds up voltage to the rated voltage, the grid-connected switch is closed to charge the line and provide power to the grid, and then the process goes to step 7);

[0065] 7) The black start of the first generator connected to the first three-winding plant transformer 34 is completed.

[0066] In this embodiment, in the step 3), the voltage of the first 35kV bus 20 and the second 35kV bus 21 is 35kV; in the step 4), the voltage of the first 400V bus 48 and the second 400V bus 49 is 400V; in the step 5), the voltage of the third 6kV bus 29 and the fourth 6kV bus 30 is 6.3kV.

[0067] 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 black start system for a thermal power plant with small hydropower, characterized in that: The invention comprises a first hydro-turbine generator (1), a second hydro-turbine generator (2), a third hydro-turbine generator (3), a fourth hydro-turbine generator (4), a fourth 6kV switch (8), a first 6kV busbar (12), a second 6kV busbar (13), a second main transformer (15), a third 35kV switch (18), a first 35kV busbar (20), a second 35kV busbar (21), a sixth 35kV switch (23), a third 6kV busbar (29), a fourth 6kV busbar (30), a ninth 6kV switch (31), a tenth 6kV switch (32), a first three-winding plant transformer (34) and a first 20kV circuit breaker (35); The first hydro-generator (1) is connected to the first 6 kV bus (12) via a first 6 kV switch (5); the second hydro-generator (2) is connected to the first 6 kV bus (12) via a third 6 kV switch (7); the third hydro-generator (3) is connected to the second 6 kV bus (13) via a fifth 6 kV switch (9); the fourth hydro-generator (4) is connected to the second 6 kV bus (13) via a seventh 6 kV switch (11); Two ends of the fourth 6kV switch (8) are respectively connected to the first 6kV busbar (12) and the second 6kV busbar (13); One end of the second main transformer (15) is connected to the second 6 kV bus (13), and the other end is connected to the second 35 kV bus (21) via a second 35 kV switch (17); One end of the third 35 kV switch (18) is connected to the second 35 kV bus (21), and the other end is connected to the first 6 kV bus (12) via the first 35 kV bus (20), the fifth 35 kV switch (22), the first 35 kV switch (16), and the first main transformer (14) in sequence; One end of the sixth 35 kV switch (23) is connected to the second 35 kV bus (21), and the other end is connected to the third 6 kV bus (29) via the third 35 kV knife switch (27), the first step-down transformer (33), and the eighth 6 kV switch (28) in sequence; One end of the first 20kV circuit breaker (35) is connected to the first generator end, and the other end is connected to the high voltage side of the first three-winding plant transformer (34); the low voltage side A branch of the first three-winding plant transformer (34) is connected to the third 6kV bus (29) via the ninth 6kV switch (31); the low voltage side B branch of the first three-winding plant transformer (34) is connected to the fourth 6kV bus (30) via the tenth 6kV switch (32).

2. A black start system for a thermal power plant with small hydropower according to claim 1, characterized in that: It also includes a second 6kV switch (6), a sixth 6kV switch (10), a fourth 35kV switch (19), a seventh 35kV switch (24), a fifth 6kV busbar (37), a sixth 6kV busbar (38), a second three-winding plant transformer (42), a second 20kV circuit breaker (43), a first 400V busbar (48), a second 400V busbar (49), a third 400V switch (50) and a 35kV output T-connected line (51); One end of the second 6kV switch (6) is connected to the first 6kV bus (12), and the other end is connected to the first 400V bus (48) via a first double-winding plant transformer (44) and a first 400V switch (46) in sequence; One end of the sixth 6kV switch (10) is connected to the second 6kV bus (13), and the other end is connected to the second 400V bus (49) via the second double-winding plant transformer (45) and the second 400V switch (47) in sequence; One end of the third 400V switch (50) is connected to the first 400V bus (48), and the other end is connected to the second 400V bus (49); One end of the fourth 35kV switch (19) is connected to the common point of the first 35kV switch (16) and the fifth 35kV switch (22), and the other end is connected to the 35kV output T-connected line (51) via the first 35kV knife switch (25); One end of the seventh 35kV switch (24) is connected to the common point of the first 35kV switch (16) and the fifth 35kV switch (22), and the other end is connected to the fifth 6kV bus (37) via the second 35kV knife switch (26), the second step-down transformer (39), and the eleventh 6kV switch (36) in sequence; One end of the second 20kV circuit breaker (43) is connected to the second generator end, and the other end is connected to the high voltage side of the second three-winding plant transformer (42); the low voltage side A branch of the second three-winding plant transformer (42) is connected to the fifth 6kV bus (37) via a twelfth 6kV switch (40); the low voltage side B branch of the second three-winding plant transformer (42) is connected to the sixth 6kV bus (38) via a thirteenth 6kV switch (41).

3. A black start system for a thermal power plant with small hydropower according to claim 2, characterized in that: When the first hydro-turbine generator (1), the second hydro-turbine generator (2), the third hydro-turbine generator (3) and the fourth hydro-turbine generator (4) all provide black start power to the load of the first three-winding plant transformer (34) or participate in AGC frequency modulation, the first 6kV switch (5), the second 6kV switch (6), the third 6kV switch (7), the fifth 6kV switch (9), the sixth 6kV switch (10), the seventh 6kV switch (11), the first 35kV switch (16), the second 35kV switch (17), the third 35kV switch (18), the fifth The 35kV switch (22), the sixth 35kV switch (23), the second 35kV knife switch (26), the third 35kV knife switch (27), the eighth 6kV switch (28), the ninth 6kV switch (31), the tenth 6kV switch (32), the first 400V switch (46), and the second 400V switch (47) are all in a closed state, and the third 400V switch (50), the fourth 35kV switch (19), the seventh 35kV switch (24), the eleventh 6kV switch (36), and the first 20kV circuit breaker (35) are all in an open state.

4. A black start system for a thermal power plant with small hydropower according to claim 3, characterized in that: When the first hydro-turbine generator (1), the second hydro-turbine generator (2), the third hydro-turbine generator (3) and the fourth hydro-turbine generator (4) all provide black start power for the load of the second three-winding plant transformer (42) or participate in AGC frequency modulation, the seventh 35kV switch (24), the second 35kV knife switch (26), the eleventh 6kV switch (36), the twelfth 6kV switch (40) and the thirteenth 6kV switch (41) are all in a closed state, and the sixth 35kV switch (23) and the third 35kV knife switch (27) are all in an open state.

5. A black start system for a thermal power plant with small hydropower according to claim 2, characterized in that: When the first hydro-turbine generator (1) and the second hydro-turbine generator (2) provide black start power for the load of the second three-winding plant transformer (42) or participate in AGC frequency modulation, when the third hydro-turbine generator (3) and the fourth hydro-turbine generator (4) provide black start power for the load of the first three-winding plant transformer (34) or participate in AGC frequency modulation, the first 6kV switch (5), the second 6kV switch (6), the third 6kV switch (7), the fifth 6kV switch (9), the sixth 6kV switch (10), the seventh 6kV switch (11), the first 35kV switch (16), the second 35kV switch (17), the sixth 35kV switch (23), the seventh 35kV switch (24), the first 35kV switch (18), the second 35kV switch (19), the sixth 35kV switch (25), the seventh 35kV switch (26) and the first 35kV switch (27) are connected to the power supply. The 5kV switch (24), the second 35kV knife switch (26), the third 35kV knife switch (27), the eighth 6kV switch (28), the ninth 6kV switch (31), the tenth 6kV switch (32), the eleventh 6kV switch (36), the twelfth 6kV switch (40), the thirteenth 6kV switch (41), the first 400V switch (46), and the second 400V switch (47) are all in a closed state, and the fourth 6kV switch (8), the third 35kV switch (18), the fourth 35kV switch (19), the fifth 35kV switch (22), the first 20kV circuit breaker (35), and the second 20kV circuit breaker (43) are all in an open state.

6. A black start system for a thermal power plant with small hydropower according to claim 1, characterized in that: When the first three-winding plant transformer (34) and the second three-winding plant transformer (42) do not perform a black start, the first hydro-turbine generator (1), the second hydro-turbine generator (2), the third hydro-turbine generator (3) and the fourth hydro-turbine generator (4) are all powered by the 35 kV output T-connection line (51), and the first 6 kV switch (5), the second 6 kV switch (6), the third 6 kV switch (7), the fifth 6 kV switch (9), the sixth 6 kV switch (10), the seventh 6 kV switch (11), the first 35 kV switch (16), the second 35 kV switch (17), the third 35 kV switch (18), the fourth 35 kV switch (19), the fifth 35 kV switch (11) are all powered by the 35 kV output T-connection line (51). The 5kV switch (22), the first 35kV knife switch (25), the ninth 6kV switch (31), the tenth 6kV switch (32), the first 20kV circuit breaker (35), the twelfth 6kV switch (40), the thirteenth 6kV switch (41), the second 20kV circuit breaker (43), the first 400V switch (46), and the second 400V switch (47) are all in a closed state, and the fourth 6kV switch (8), the sixth 35kV switch (23), the seventh 35kV switch (24), the second 35kV knife switch (26), the third 35kV knife switch (27), the eighth 6kV switch (28), and the eleventh 6kV switch (36) are all in an open state.

7. A black start system for a thermal power plant with small hydropower according to claim 4, characterized in that: When the first hydro-turbine generator (1), the second hydro-turbine generator (2), the third hydro-turbine generator (3) and the fourth hydro-turbine generator (4) all assist the first three-winding plant transformer (34) or the second three-winding plant transformer (42) in participating in AGC frequency modulation, the power grid frequency is stabilized by adjusting the power of the first hydro-turbine generator (1), the second hydro-turbine generator (2), the third hydro-turbine generator (3) and the fourth hydro-turbine generator (4) and tracking the AGC target instruction.

8. A black start method for a thermal power plant with small hydropower, characterized in that: The system according to any one of claims 2 to 7 comprises the following steps: 1) disconnect the fourth 6kV switch (8), the fourth 35kV switch (19), the seventh 35kV switch (24), the second 35kV knife switch (26), and the first 20kV circuit breaker (35) in sequence, and proceed to step 2); 2) Close the first 6kV switch (5), the second 6kV switch (6), the third 6kV switch (7), the fifth 6kV switch (9), and the sixth 6kV switch (10) in sequence; the seventh 6kV switch (11), the first 35kV switch (16), the second 35kV switch (17), the third 35kV switch (18), the fifth 35kV switch (22), the sixth 35kV switch (23), the ninth 6kV switch (31), and the tenth 6kV switch (32) in sequence, and proceed to step 3); 3) adjusting the voltage of the first hydro-generator (1), the second hydro-generator (2), the third hydro-generator (3) and the fourth hydro-generator (4) to a rated voltage of 6.3 kV, and proceeding to step 4); 4) Close the first 400V switch (46) and the second 400V switch (47), and proceed to step 5); 5) The eighth 6kV switch (28) is closed, and the loads of the third 6kV bus (29) and the fourth 6kV bus (30) are powered by the first hydro-generator (1), the second hydro-generator (2), the third hydro-generator (3), and the fourth hydro-generator (4), and the process proceeds to step 6); 6) The first generator connected to the first three-winding plant transformer (34) is ignited, started, maintained at a constant speed, and voltage is built up. After the voltage of the first generator reaches the rated voltage, the grid-connected switch is closed to charge the line and provide power to the grid, and then the process proceeds to step 7); 7) The black start of the first generator connected to the first three-winding plant transformer (34) is completed.

9. A black start method for a thermal power plant with small hydropower according to claim 8, characterized in that: In the step 3), the voltage of the first 35kV bus (20) and the second 35kV bus (21) is 35kV; in the step 4), the voltage of the first 400V bus (48) and the second 400V bus (49) is 400V; in the step 5), the voltage of the third 6kV bus (29) and the fourth 6kV bus (30) is 6.3kV.

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