CN112311011A - Thermal power plant black start system with small hydropower and method - Google Patents

Abstract

The invention relates to a black start system and a black start method for a thermal power plant with small hydropower, which comprises a first hydraulic generator, a second hydraulic generator, a third hydraulic generator, a fourth hydraulic generator, a first main transformer, a second main transformer, a first step-down transformer, a second step-down transformer, a first three-winding service transformer, a second three-winding service transformer, a first double-winding service transformer, a second double-winding service transformer and a 35kV outgoing T-junction circuit, wherein the first hydraulic generator is connected with the first hydraulic generator through a first main transformer and a second main transformer; after the line sent by the thermal power unit loses power, the thermal power unit is quickly started through small hydropower in the thermal power plant, the small hydropower supplies power to one section of bus of a power system of the thermal power plant, the other section of bus is connected with a small hydropower bus and passes through a three-winding transformer to supply power, the two sections of power system buses of the thermal power plant recover to supply power, and the power system loses power quickly; when the thermal power generating unit output line normally runs, the small-sized water and electricity can assist the thermal power generating unit to participate in AGC frequency modulation or supply power to a power grid through a T connection line.

Description

Thermal power plant black start system with small hydropower and method

Technical Field

The invention belongs to the technical field of black start of a thermal power plant with small hydropower, and particularly relates to a black start system and method of the thermal power plant with the small hydropower.

Background

At present, black start in China mainly comprises water, electricity and a gas turbine, thermal power is limited by too many factors and does not have black start capability, the main reason is that a plurality of thermal power auxiliary machines are arranged, a large power supply is needed during black start to drive the thermal power auxiliary machines to operate, meanwhile, after power grid power loss occurs, after the thermal power plant uses the auxiliary machines for a period of time, the temperatures of a boiler and a steam turbine gradually transit towards a cold state, and when all complex processes have no faults, restarting is carried out for several hours or more than one day, so that thermal power is a key technology for limiting black start due to special operation conditions and physical characteristics of the thermal power. The condition that the thermal power has the black start capability is that after the power grid loses power, all auxiliary machines can be switched to a power supply with larger capacity for supplying power, namely the power supply can be rapidly sent out in a short time under the condition of extreme hot states of a boiler and a steam turbine, and at present, the thermal power urgently needs a power supply which can store energy and is controllable and has larger capacity than auxiliary machines for factories to realize black start.

The current black start technology of the thermal power plant mainly has the following problems: (1) the thermal power plant has no capacity except for starting the standby power supply, so that the black starting capability of the thermal power plant is restricted due to the fact that the thermal power plant can start the controllable small-sized water power; (2) relevant literature data of small hydropower auxiliary thermal power plant units for thermal power plants are not seen; (3) at present, no case and report for AGC (automatic gain control) frequency modulation of a small hydropower auxiliary thermal power generating unit exists; (4) at present, no related technology for realizing the starting of the small hydroelectric auxiliary thermal power generating unit by utilizing the penetration power supply of a three-winding transformer exists.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a black start system and a black start method for a thermal power plant with small hydropower, which can enable a thermal power unit to have black start capability and provide safety guarantee for a power grid.

The invention is realized by the following technical scheme:

a thermal power plant black start system with small hydropower stations comprises a first hydro-generator, a second hydro-generator, a third hydro-generator, a fourth 6kV switch, a first 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;

the first hydraulic generator is connected with the first 6kV bus through a first 6kV switch; the second water wheel generator is connected with the first 6kV bus through a third 6kV switch; the third water wheel generator is connected with the second 6kV bus through a fifth 6kV switch; the fourth water wheel generator is connected with the second 6kV bus through a seventh 6kV switch;

two ends of the fourth 6kV switch are respectively connected with the first 6kV bus and the second 6kV bus;

one end of the second main transformer is connected with the second 6kV bus, and the other end of the second main transformer is connected with the second 35kV bus through a second 35kV switch;

one end of the third 35kV switch is connected with the second 35kV bus, and the other end of the third 35kV switch is connected with the first 6kV bus through the first 35kV bus, the fifth 35kV switch, the first 35kV switch and the first main transformer in sequence;

one end of the sixth 35kV switch is connected with the second 35kV bus, and the other end of the sixth 35kV switch is connected with the third 6kV bus through a third 35kV disconnecting link, a first step-down transformer and an eighth 6kV switch in sequence;

one end of the first 20kV circuit breaker is connected with the end of the first generator, the other end of the first 20kV circuit breaker is connected with the high-voltage side of the first three-winding station transformer, the low-voltage side A branch of the first three-winding station transformer is connected with the third 6kV bus through the ninth 6kV switch, and the low-voltage side B branch of the first three-winding station transformer is connected with the fourth 6kV bus through the tenth 6kV switch.

Preferably, the system further comprises 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 third winding station transformer, a second 20kV circuit breaker, a first 400V bus, a second 400V bus, a third 400V switch and a 35kV outgoing T wiring circuit;

one end of the second 6kV switch is connected with the first 6kV bus, and the other end of the second 6kV switch is connected with the first 400V bus through a first double-winding station transformer and a first 400V switch in sequence;

one end of the sixth 6kV switch is connected with the second 6kV bus, and the other end of the sixth 6kV switch is connected with the second 400V bus through a second double-winding station transformer and a second 400V switch in sequence;

one end of the third 400V switch is connected with the first 400V bus, and the other end of the third 400V switch is connected with the second 400V bus;

one end of the fourth 35kV switch is connected with the common point of the first 35kV switch and the fifth 35kV switch, and the other end of the fourth 35kV switch is connected with the 35kV outgoing T-junction circuit through the first 35kV disconnecting link;

one end of the seventh 35kV switch is connected with the common point of the first 35kV switch and the fifth 35kV switch, and the other end of the seventh 35kV switch is connected with the fifth 6kV bus through a second 35kV disconnecting link, a second step-down transformer and an eleventh 6kV switch in sequence;

one end of the second 20kV circuit breaker is connected with the end of the second generator, the other end of the second 20kV circuit breaker is connected with the high-voltage side of the second three-winding station transformer, the low-voltage side A branch of the second three-winding station transformer is connected with the fifth 6kV bus through the twelfth 6kV switch, and the low-voltage side B branch of the second three-winding station transformer is connected with the sixth 6kV bus through the thirteenth 6kV switch.

Further, when the first hydro-generator, the second hydro-generator, the third hydro-generator and the fourth hydro-generator are all the first three-winding service transformer load providing a black start power or participating 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-to-state.

Further, when the first water-wheel generator, the second water-wheel generator, the third water-wheel generator and the fourth water-wheel generator are all provided with a black starting power supply or participate in AGC frequency modulation by the load of the second three-winding service transformer, the seventh 35kV switch, the second 35kV disconnecting link, 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 disconnecting link are all in an open state.

Preferably, when the first hydro-generator and the second hydro-generator provide a black start power for the second three-winding plant transformer load or participate in AGC frequency modulation, and when the third hydro-generator and the fourth hydro-generator provide a 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 seventh 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 ninth 6kV switch, the tenth 6kV switch, the eleventh 6kV switch, the thirteenth 6kV switch, the first 400V switch and the second 400V switch are all in a closed state, 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 off state.

Preferably, when the first three-winding station transformer and the second three-winding station transformer are not in 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 outgoing T-junction circuit, 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 fourth 35kV switch, the fifth 35kV switch, the first 35kV disconnecting link, the ninth 6kV switch, the tenth 6kV switch, the first 20kV circuit breaker, the twelfth 6kV switch, the thirteenth 6kV switch, the second 20kV circuit breaker, the first 400V switch and the second 400V switch are all in a closed state, and the fourth 6kV switch, the sixth 35kV switch, the seventh 35kV circuit breaker, the thirteenth 6kV circuit breaker, the fourth 35kV circuit breaker, the fifth 400V switch and the fourth 35kV circuit breaker are all in a closed state, The second 35kV disconnecting link, the third 35kV disconnecting link, the eighth 6kV switch and the eleventh 6kV switch are all in an off state.

Furthermore, the first water-wheel generator, the second water-wheel generator, the third water-wheel generator and the fourth water-wheel generator all assist the first three-winding service transformer or the second three-winding service transformer to participate in AGC frequency modulation, and power of the first water-wheel generator, the second water-wheel generator, the third water-wheel generator and the fourth water-wheel generator is adjusted and an AGC target instruction is tracked, so that the frequency of the power grid is stabilized.

A black start method of a thermal power plant with small hydropower comprises the following steps:

1) sequentially disconnecting the fourth 6kV switch, the fourth 35kV switch, the seventh 35kV switch, the second 35kV disconnecting link and the first 20kV circuit breaker, and entering the step 2);

2) sequentially closing the first 6kV switch, the second 6kV switch, the third 6kV switch, the fifth 6kV switch and the sixth 6kV switch; a seventh 6kV switch, a first 35kV switch, a second 35kV switch, a third 35kV switch, a fifth 35kV switch, a sixth 35kV switch, a ninth 6kV switch and a tenth 6kV switch, and entering step 3);

3) adjusting the voltage build-up of the first hydraulic generator, the second hydraulic generator, the third hydraulic generator and the fourth hydraulic generator to be 6.3kV of rated voltage, and entering the step 4);

4) closing the first 400V switch and the second 400V switch, and entering the step 5);

5) closing the eighth 6kV switch, wherein the third 6kV bus and the fourth 6kV bus are supplied with power by the first water wheel generator, the second water wheel generator, the third water wheel generator and the fourth water wheel generator, and entering the step 6);

6) igniting, impulse rotating, constant speed and voltage building are carried out on a first generator accessed by the first three-winding station transformer, after the voltage building of the first generator reaches rated voltage, a grid-connected switch is closed, a circuit is charged, a power supply is provided for a power grid, and the step 7 is carried out;

7) and ending black start of the first generator accessed by the first three-winding service transformer.

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

Compared with the prior art, the invention has the following beneficial technical effects:

after the thermal power unit sends out a line and loses power, the system is quickly started through small hydropower in the thermal power plant, the small hydropower supplies power to one section of bus of a power system of the thermal power plant, the other section of bus is connected with a small hydropower bus and passes through a three-winding transformer to supply power, the two sections of buses for the power plant recover power supply, and the unit is started, fixed in speed and built according to an extreme thermal state program and quickly recovers power supply to the power losing system; when the transmission line of the thermal power generating unit normally runs, the small-sized water and electricity can assist the thermal power generating unit to participate in AGC frequency modulation or supply power to a power grid through a T-connection line; the invention provides a novel thermal power black start system and a novel thermal power black start method, which enable a thermal power unit to have black start capability, improve the safety and stability of a power grid, participate in AGC (automatic gain control) frequency modulation of the power grid to increase the economic benefits of operation of the thermal power unit, flexibly switch the operation modes of small hydropower stations aiming at different application scenes, and meet the requirements of daily safety, frequency modulation and power supply of the power grid.

Furthermore, the small hydropower station is flexible in wiring during black start, can supply power for one or two thermal power unit plant systems, realizes electrode thermal state start of the thermal power units and sends out power, provides a black start power supply with large capacity and reliability for a power grid, and reduces power failure pressure of the power grid.

Furthermore, any section of the bus at the low-voltage side of the three-winding transformer is powered by small hydropower, and the other section of the bus is powered by the three-winding transformer in a penetrating way, so that the investment of primary equipment can be reduced, the wiring of the system is simplified, and the operation flexibility is enhanced.

Furthermore, when the power grid normally operates, the small hydropower station can participate in AGC frequency modulation of one or two thermal power units, so that the frequency of the power grid is stabilized, the natural advantages of the thermal power unit with the small hydropower station are exerted, the thermal power unit is assisted in outputting to follow and match AGC instructions, and the frequency modulation performance and the economic benefit of the thermal power unit are improved; according to the invention, the electrochemical energy storage is not required to be additionally added to the thermal power generating unit, and the frequency modulation safety of the thermal power generating unit is improved.

Furthermore, the small hydropower station can also send a power supply to a power grid through the T-connection circuit, so that the investment cost of the circuit is reduced, and high-quality and high-cost-performance green energy is provided for the power grid.

Drawings

FIG. 1 is a schematic diagram of the system of the present invention.

Fig. 2 is a schematic diagram of the first, second, third and fourth hydraulic generators of the present invention, which are all the first three-winding service transformer load providing black start power or participating in AGC frequency modulation.

Fig. 3 is a schematic diagram of the first water-wheel generator, the second water-wheel generator, the third water-wheel generator and the fourth water-wheel generator all providing black start power for the load of the second three-winding service transformer or participating in AGC frequency modulation.

Fig. 4 is a schematic diagram of a first hydraulic generator and a second hydraulic generator of the present invention providing a black start power supply for a second three-winding service transformer load or participating in AGC frequency modulation, and a third hydraulic generator and a fourth hydraulic generator providing a black start power supply for a first three-winding service transformer load or participating in AGC frequency modulation.

FIG. 5 is a schematic diagram of the power supply principle of the first, second, third and fourth hydraulic generators of the present invention, all of which are 35kV and are fed out of a T-junction circuit.

In the figure: 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 second 6kV switch 6; a third 6kV switch 7; a fourth 6kV switch 8; a fifth 6kV switch 9; a sixth 6kV switch 10; 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 fourth 35kV switch 19; a first 35kV bus 20; a second 35kV bus 21; a fifth 35kV switch 22; a sixth 35kV switch 23; a seventh 35kV switch 24; a first 35kV knife switch 25; a second 35kV knife switch 26; a third 35kV disconnecting link 27; an eighth 6kV switch 28; a third 6kV bus 29; a fourth 6kV bus 30; a ninth 6kV switch 31; a tenth 6kV switch 32; a first step-down transformer 33; a first three-winding service transformer 34; a first 20kV circuit breaker 35; an eleventh 6kV switch 36; a fifth 6kV bus 37; a sixth 6kV bus 38; a second step-down transformer 39; a twelfth 6kV switch 40; a thirteenth 6kV switch 41; a second third winding service transformer 42; a second 20kV circuit breaker 43; a first dual-winding service transformer 44; a second dual-winding service transformer 45; a first 400V switch 46; a second 400V switch 47; a first 400V bus bar 48; a second 400V bus 49; a third 400V switch 50; the 35kV outgoing T-junction line 51.

Detailed Description

The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.

The invention can solve the problems of black start and frequency modulation of the thermal power generating unit, reduces the investment of primary equipment by utilizing a transformer ride-through power supply mode, enables the thermal power generating unit to have black start capability, exerts the natural advantages of a small hydroelectric generating unit, participates in AGC frequency modulation or external power supply of the thermal power generating unit, and improves the operation flexibility of the thermal power generating unit.

The invention relates to a black start system and a black start method for a thermal power plant with small hydropower, which comprises a first hydraulic generator, a second hydraulic generator, a third hydraulic generator, a fourth hydraulic generator, a first main transformer, a second main transformer, a first step-down transformer, a second step-down transformer, a first three-winding service transformer, a second three-winding service transformer, a first double-winding service transformer, a second double-winding service transformer and a 35kV outgoing T-junction circuit, wherein the first hydraulic generator is connected with the first hydraulic generator through a first main transformer and a second main transformer; after the thermal power unit sends out a line and loses power, the system is quickly started through small hydropower in the thermal power plant, the small hydropower supplies power to one section of bus of a power system of the thermal power plant, the other section of bus is connected with a small hydropower bus and passes through a three-winding transformer to supply power, the two sections of buses for the power plant recover power supply, and the unit is started, fixed in speed and built according to an extreme thermal state program and quickly recovers power supply to the power losing system; when the transmission line of the thermal power generating unit normally runs, the small-sized water and electricity can assist the thermal power generating unit to participate in AGC frequency modulation or supply power to a power grid through a T-connection line; the novel thermal power black start system and the method have the advantages that the thermal power unit has black start capacity, the safety and stability of a power grid are improved, the power grid AGC frequency modulation can be participated to increase the economic benefits of operation of the thermal power unit, the operation modes of small hydropower stations are flexibly switched according to different application scenes, and the daily safety, frequency modulation and power supply requirements of the power grid are met.

As shown in fig. 1, the present invention is a black start system of a thermal power plant with small hydroelectric power, the device comprises a first water wheel generator 1, a second water wheel generator 2, a third water wheel generator 3, a fourth water wheel 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, a sixth 35kV switch 23, a third 35kV disconnecting link 27, an eighth 6kV switch 28, a third 6kV bus 29, a fourth 6kV bus 30, a ninth 6kV switch 31, a tenth 6kV switch 32, a first step-down transformer 33, a first three-winding transformer 34 for plant use and a first 20kV circuit breaker 35; wherein, the first water wheel generator 1 is connected with the first 6kV bus 12 through a first 6kV switch 5, the second water wheel generator 2 is connected with the first 6kV bus 12 through a third 6kV switch 7, the third water wheel generator 3 is connected with the second 6kV bus 13 through a fifth 6kV switch 9, the fourth water wheel generator 4 is connected with the second 6kV bus 13 through a seventh 6kV switch 11, one end of the second main transformer 15 is connected with the second 6kV bus 13, the other end is connected with the second 35kV bus 21 through a second 35kV switch 17, one end of the third 35kV switch 18 is connected with the second 35kV bus 21, the other end is connected with the first 6kV bus 12 through a first 35kV bus 20, a fifth 35kV switch 22, a first 35kV switch 16 and a first 6kV bus 14 in sequence, one end of the sixth 35kV switch 23 is connected with the second 35kV bus 21, the other end in proper order through third 35kV switch 27, first step-down transformer 33, eighth 6kV switch 28 with third 6kV generating line 29 links to each other, first 20kV circuit breaker 35 one end links to each other with first generator terminal, the other end with first three winding house service transformer 34 high-pressure side links to each other, first three winding house service transformer 34 low-voltage side A branch through ninth 6kV switch 31 with third 6kV generating line 29 links to each other, first three winding house service transformer 34 low-voltage side B branch through tenth 6kV switch 32 with fourth 6kV generating line 30 links to each other. .

In this embodiment, the system further includes a second 6kV switch 6, a sixth 6kV switch 10, a fourth 35kV switch 19, a seventh 35kV switch 24, a first 35kV disconnecting link 25, a second 35kV disconnecting link 26, an eleventh 6kV switch 36, a fifth 6kV bus 37, a sixth 6kV bus 38, a second step-down transformer 39, a twelfth 6kV switch 40, a thirteenth 6kV switch 41, a second three-winding service transformer 42, a second 20kV circuit breaker 43, a first dual-winding service transformer 44, a second dual-winding service transformer 45, a first 400V switch 46, a second 400V switch 47, a first 400V bus 48, a second 400V bus 49, a third 400V switch 50, and a 35kV outgoing T-junction circuit 51; one end of the second 6kV switch 6 is connected to the first 6kV bus 12, the other end of the second 6kV switch is connected to the first 400V bus 48 through a first double-winding station 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, the other end of the sixth 6kV switch is connected to the second 400V bus 49 through a second double-winding station transformer 45 and a 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 of the third 400V switch is connected to the second 400V bus 49; one end of the fourth 35kV switch 19 is connected with the common point of the first 35kV switch 16 and the fifth 35kV switch 22, the other end is connected with the 35kV sending-out T-connection circuit 51 through the first 35kV disconnecting link 25, one end of the seventh 35kV switch 24 is connected with the common point of the first 35kV switch 16 and the fifth 35kV switch 22, the other end is connected with the fifth 6kV bus 37 through a second 35kV disconnecting link 26, a second step-down transformer 39 and an eleventh 6kV switch 36 in sequence, one end of the second 20kV breaker 43 is connected with the end of the second generator, the other end is connected with the high-voltage side of the second three-winding service transformer 42, the low-voltage side a branch of the second three-winding service transformer 42 is connected with the fifth 6kV bus 37 through a twelfth 6kV switch 40, the low-voltage side B branch of the second three-winding station transformer 42 is connected with the sixth 6kV bus 38 through a thirteenth 6kV switch 41.

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

In this embodiment, the rated capacities of the first dual-winding service transformer 44 and the second dual-winding service transformer are 315kVA, and the number of the connection group is DY 11; the first main transformer 14 and the second main transformer 15 have a rated capacity of 12500kVA, and the joint group is labeled Ynd 11.

As shown in fig. 2, when the first hydro-generator 1, the second hydro-generator 2, the third hydro-generator 3, and the fourth hydro-generator 4 are all the first three-winding service transformer 34 load providing black start power or participating 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 switch 26, the third 35kV 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, the first 400V switch 46, and the second 400V switch 47 are all in a closed state, The first 20kV circuit breakers 35 are all in a breaking transition state; the rated voltage of the first hydraulic generator 1, the second hydraulic generator 2, the third hydraulic generator 3 and the fourth hydraulic 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 station transformer 34 and the second three-winding station transformer 42 is 20kV/6.3kV/6.3kV, and the transformation ratio of the first double-winding station transformer 44 and the second double-winding station transformer 45 is 6.3kV/0.4 kV.

As shown in fig. 3, when the first water-turbine generator 1, the second water-turbine generator 2, the third water-turbine generator 3, and the fourth water-turbine generator 4 are all the second three-winding service transformer 42 load providing a black start power supply or participating in AGC frequency modulation, the seventh 35kV switch 24, the second 35kV disconnecting link 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 disconnecting link 27 are all in an open state.

As shown in fig. 4, when the first hydro-generator 1 and the second hydro-generator 2 provide black start power for the load of the second three-winding service transformer 42 or participate in AGC frequency modulation, and when the third hydro-generator 3 and the fourth hydro-generator 4 provide black start power for the load of the first three-winding service 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 second 35kV disconnecting link 26, the third 35kV disconnecting link 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, the third 400V switch 46, and the third 6kV switch, The second 400V switch 47 is 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 in an open state.

As shown in fig. 5, when the first three-winding service transformer 34 and the second three-winding service transformer 42 are not in 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 supplied with power by the 35kV sending-out T connection circuit 51, 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, the fourth 6kV switch 8, the sixth 35kV switch 23, the seventh 35kV switch 24, the second 35kV disconnecting link 26, the third 35kV disconnecting link 27, the eighth 6kV switch 28 and the eleventh 6kV switch 36 are all in an off state.

In this embodiment, the first hydraulic generator 1, the second hydraulic generator 2, the third hydraulic generator 3, and the fourth hydraulic generator 4 all assist the first three-winding service transformer 34 or the second three-winding service transformer 42 to participate in AGC frequency modulation, and stabilize the power grid frequency by adjusting the power of the first hydraulic generator 1, the second hydraulic generator 2, the third hydraulic generator 3, and the fourth hydraulic generator 4 and tracking an AGC target instruction.

A black start method of a thermal power plant with small hydropower comprises the following steps:

1) sequentially disconnecting the fourth 6kV switch 8, the fourth 35kV switch 19, the seventh 35kV switch 24, the second 35kV disconnecting link 26 and the first 20kV circuit breaker 35, and entering the step 2);

2) sequentially closing 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; a seventh 6kV switch 11, a first 35kV switch 16, a second 35kV switch 17, a third 35kV switch 18, a fifth 35kV switch 22, a sixth 35kV switch 23, a ninth 6kV switch 31, a tenth 6kV switch 32, and go to step 3);

3) adjusting the pressure build-up of the first hydraulic generator 1, the second hydraulic generator 2, the third hydraulic generator 3 and the fourth hydraulic generator 4 to the rated voltage of 6.3kV, and entering the step 4);

4) closing the first 400V switch 46 and the second 400V switch 47, and entering the step 5);

5) closing the eighth 6kV switch 28, supplying power to the third 6kV bus 29 and the fourth 6kV bus 30 by the first hydraulic generator 1, the second hydraulic generator 2, the third hydraulic generator 3 and the fourth hydraulic generator 4 in a load manner, and entering the step 6);

6) igniting, impulse rotating, constant speed and voltage building are carried out on a first generator accessed by the first three-winding factory transformer 34, after the voltage building of the first generator reaches rated voltage, a grid-connected switch is closed, a line is charged, a power supply is provided for a power grid, and the step 7) is carried out;

7) and ending the black start of the first generator accessed by the first three-winding service transformer 34.

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

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all simple modifications, changes and equivalent structural changes made to the above embodiment according to the technical spirit of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims (9)

1. A black start system with small hydropower for a thermal power plant is characterized by comprising a first water wheel generator (1), a second water wheel generator (2), a third water wheel generator (3), a fourth water wheel generator (4), a fourth 6kV switch (8), a first 6kV bus (12), a second 6kV bus (13), a second main transformer (15), a third 35kV switch (18), a first 35kV bus (20), a second 35kV bus (21), a sixth 35kV switch (23), a third 6kV bus (29), a fourth 6kV bus (30), a ninth 6kV switch (31), a tenth 6kV switch (32), a transformer (34) for a first plant winding and a first 20kV circuit breaker (35);

the first hydro-generator (1) is connected with the first 6kV bus (12) through a first 6kV switch (5); the second water wheel generator (2) is connected with the first 6kV bus (12) through a third 6kV switch (7); the third water wheel generator (3) is connected with the second 6kV bus (13) through a fifth 6kV switch (9); the fourth water wheel generator (4) is connected with the second 6kV bus (13) through a seventh 6kV switch (11);

two ends of the fourth 6kV switch (8) are respectively connected with a first 6kV bus (12) and a second 6kV bus (13);

one end of the second main transformer (15) is connected with the second 6kV bus (13), and the other end of the second main transformer is connected with the second 35kV bus (21) through a second 35kV switch (17);

one end of the third 35kV switch (18) is connected with the second 35kV bus (21), and the other end of the third 35kV switch is connected with the first 6kV bus (12) through a first 35kV bus (20), a fifth 35kV switch (22), a first 35kV switch (16) and a first main transformer (14) in sequence;

one end of the sixth 35kV switch (23) is connected with the second 35kV bus (21), and the other end of the sixth 35kV switch is connected with the third 6kV bus (29) through a third 35kV disconnecting link (27), a first step-down transformer (33) and an eighth 6kV switch (28) in sequence;

first 20kV circuit breaker (35) one end links to each other with first generator terminal, the other end with first three winding house service transformer (34) high-pressure side links to each other, first three winding house service transformer (34) low pressure side A branch through ninth 6kV switch (31) with third 6kV generating line (29) link to each other, first three winding house service transformer (34) low pressure side B branch through tenth 6kV switch (32) with fourth 6kV generating line (30) link to each other.

2. The black start system of a thermal power plant with small hydropower according to claim 1, further comprising a second 6kV switch (6), a sixth 6kV switch (10), a fourth 35kV switch (19), a seventh 35kV switch (24), a fifth 6kV bus (37), a sixth 6kV bus (38), a second three-winding service transformer (42), a second 20kV circuit breaker (43), a first 400V bus (48), a second 400V bus (49), a third 400V switch (50), and a 35kV outgoing T-connection (51);

one end of the second 6kV switch (6) is connected with the first 6kV bus (12), and the other end of the second 6kV switch is connected with the first 400V bus (48) through a first double-winding station transformer (44) and a first 400V switch (46) in sequence;

one end of the sixth 6kV switch (10) is connected with the second 6kV bus (13), and the other end of the sixth 6kV switch is connected with the second 400V bus (49) through a second double-winding station transformer (45) and a second 400V switch (47) in sequence;

one end of the third 400V switch (50) is connected with the first 400V bus (48), and the other end of the third 400V switch is connected with the second 400V bus (49);

one end of the fourth 35kV switch (19) is connected with the common point of the first 35kV switch (16) and the fifth 35kV switch (22), and the other end of the fourth 35kV switch is connected with the 35kV sending-out T-junction circuit (51) through a first 35kV disconnecting link (25);

one end of the seventh 35kV switch (24) is connected with a common point of the first 35kV switch (16) and the fifth 35kV switch (22), and the other end of the seventh 35kV switch is connected with the fifth 6kV bus (37) through a second 35kV disconnecting link (26), a second step-down transformer (39) and an eleventh 6kV switch (36) in sequence;

second 20kV circuit breaker (43) one end links to each other with the second generator terminal, the other end with second three winding house transformer (42) high-pressure side links to each other, second three winding house transformer (42) low pressure side A branch through twelfth 6kV switch (40) with fifth 6kV generating line (37) link to each other, second three winding house transformer (42) low pressure side B branch through thirteenth 6kV switch (41) with sixth 6kV generating line (38) link to each other.

3. The thermal power plant black start system with small hydropower of claim 2, wherein the first hydro-generator (1), the second hydro-generator (2), the third hydro-generator (3) and the fourth hydro-generator (4) are respectively provided with a black start power supply or participate in AGC frequency modulation when the first three-winding plant transformer (34) is loaded, 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 fifth 35kV switch (22), the sixth 35kV switch (23), the second 35kV switch (26), the third 35kV 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. The thermal power plant black start system with small hydropower according to claim 3, wherein the first water-turbine generator (1), the second water-turbine generator (2), the third water-turbine generator (3) and the fourth water-turbine generator (4) are all in a closed state of the seventh 35kV switch (24), the second 35kV switch (26), the eleventh 6kV switch (36), the twelfth 6kV switch (40) and the thirteenth 6kV switch (41) when the second three-winding plant transformer (42) is loaded to provide black start power or participate in AGC frequency modulation, and the sixth 35kV switch (23) and the third 35kV switch (27) are all in an open state.

5. The thermal power plant black start system with small hydropower according to claim 1, wherein the first and second water-turbine generators (1, 2) provide black start power for the second three-winding service transformer (42) load or participate in AGC frequency modulation, and the first and fourth water-turbine generators (5, 6kV, 7, 6kV, 9, 10, 11, 35kV, 16, 17, 23, 35kV, 24, 26 and the third and fourth water-turbine generators (3, 4) provide black start power for the first three-winding service transformer (34) load or participate in AGC frequency modulation, 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 breaker (35) and the second 20kV breaker (43) are all in an open state.

6. The thermal power plant black start system with small hydropower according to claim 1, wherein the first three-winding plant transformer (34) and the second three-winding plant transformer (42) are all powered by the 35kV outgoing T-junction line (51) when not performing black start, 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 breaker (35), the twelfth 6kV switch (40), the thirteenth 6kV switch (41), the second 20kV 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. The thermal power plant black start system with small hydropower according to claim 4, wherein the first hydraulic generator (1), the second hydraulic generator (2), the third hydraulic generator (3) and the fourth hydraulic generator (4) are all used for assisting the first three-winding service transformer (34) or the second three-winding service transformer (42) to stabilize the power grid frequency by adjusting the power of the first hydraulic generator (1), the second hydraulic generator (2), the third hydraulic generator (3) and the fourth hydraulic generator (4) and tracking an AGC target instruction when participating in AGC frequency modulation.

8. A black start method for a thermal power plant with small hydropower is characterized by comprising the following steps:

1) sequentially disconnecting the fourth 6kV switch (8), the fourth 35kV switch (19), the seventh 35kV switch (24), the second 35kV disconnecting link (26) and the first 20kV circuit breaker (35), and entering the step 2;

2) sequentially closing 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); a seventh 6kV switch (11), a first 35kV switch (16), a second 35kV switch (17), a third 35kV switch (18), a fifth 35kV switch (22), a sixth 35kV switch (23), a ninth 6kV switch (31), and a tenth 6kV switch (32), and the step 3 is performed;

3) adjusting the pressure build-up of the first hydraulic generator (1), the second hydraulic generator (2), the third hydraulic generator (3) and the fourth hydraulic generator (4) to a rated voltage of 6.3kV, and entering the step 4);

4) closing the first 400V switch (46) and the second 400V switch (47), and entering step 5);

5) closing the eighth 6kV switch (28), supplying power to the third 6kV bus (29) and the fourth 6kV bus (30) by the first water turbine generator (1), the second water turbine generator (2), the third water turbine generator (3) and the fourth water turbine generator (4) in load, and entering step 6);

6) a first generator accessed by the first three-winding station transformer (34) is ignited, rushed to rotate, fixed in speed and built up in voltage, after the voltage of the first generator is built up to a rated voltage, a grid-connected switch is closed, a line is charged, a power supply is provided for a power grid, and the step 7 is carried out;

7) and ending black start of the first generator accessed by the first three-winding service transformer (34).

9. The black start system of a thermal power plant with small hydropower according to claim 8, wherein the voltage of the first 35kV bus (20) and the second 35kV bus (21) in the step 3) is 35 kV; the voltage of the first 400V bus (48) and the second 400V bus (49) in the step 4) is 400V; and in the step 5), the voltages of the third 6kV bus (29) and the fourth 6kV bus (30) are 6.3 kV.

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