An energy-saving power supply system and usage method for a high-voltage frequency conversion starting device of a generator set

Abstract

The present invention relates to an energy-saving power supply system and a usage method for a high-voltage frequency conversion starting device of a generator set, including a high-voltage frequency conversion starting device, a main transformer, a high-voltage auxiliary transformer, a generator, a generator outlet circuit breaker, a high-voltage starting standby transformer, a bus unit, a first power supply unit, and a second power supply unit. The generator is respectively connected to the low-voltage side of the main transformer and the high-voltage side of the high-voltage auxiliary transformer through the generator outlet circuit breaker. The high-voltage side of the main transformer is connected to the bus unit through the first power supply unit. The bus unit is connected to the high-voltage side of the high-voltage starting standby transformer through the second power supply unit. The balance winding of the high-voltage starting standby transformer is connected to the high-voltage frequency conversion starting device through an outgoing line bushing. The high-voltage frequency conversion starting device is connected to the generator. It can reduce the capacity of the high-voltage auxiliary transformer, thereby reducing energy consumption, and reducing the power supply nodes, improving the power supply reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply for generator sets, in particular to an energy-saving power supply system and a usage method for a high-voltage frequency conversion starting device of a generator set. Background Art

[0002] When a gas turbine generator set starts, the gas turbine generator is used as a synchronous motor and needs to supply power to the stator of the gas turbine generator through a high-voltage frequency conversion starting device to drive the unit to increase speed. Until the speed reaches about 2000 r.p.m, the power output by the thermal turbine can maintain the rotation of the unit and generate power to continue increasing speed or generating electricity, and the high-voltage frequency conversion starting device exits operation.

[0003] The power supply of the existing high-voltage frequency conversion starting device is drawn from the 6 kV section of the high-voltage auxiliary power supply section of the gas turbine power plant. The high-voltage frequency conversion starting device is often the largest load in the high-voltage auxiliary power supply section of the gas turbine power plant, occupying a large proportion of the capacity of the high-voltage auxiliary transformer and the high-voltage starting standby transformer. This makes the capacity of the high-voltage auxiliary transformer and the high-voltage starting standby transformer large, and the corresponding parameter requirements for the 6 kV switchgear are high. The thermal stability cross-section of the 6 kV cable and bus is large, resulting in a high investment in the 6 kV auxiliary power supply system of the gas turbine power plant. Moreover, the power supply path of the high-voltage frequency conversion starting device is: high-voltage starting standby transformer - 6 kV section of the high-voltage auxiliary power supply section - high-voltage frequency conversion starting device, adding a power supply node in the 6 kV section of the high-voltage auxiliary power supply section and increasing the probability of failure. Summary of the Invention

[0004] The purpose of the present invention is to provide an energy-saving power supply system for a high-voltage frequency conversion starting device of a gas turbine generator set, which can reduce the capacity of the high-voltage auxiliary transformer, thereby reducing energy consumption, reducing the number of power supply nodes, and improving power supply reliability.

[0005] To achieve the above object, the present invention provides the following technical solution: An energy-saving power supply system for a high-voltage frequency conversion starting device of a gas turbine generator set, characterized in that it includes a high-voltage frequency conversion starting device, a main transformer, a high-voltage auxiliary transformer, a generator, a generator outlet circuit breaker, a high-voltage starting standby transformer, a bus unit, a first power supply unit, a second power supply unit, a first outgoing line unit, a second outgoing line unit, a first auxiliary low-voltage unit, and a second auxiliary low-voltage unit. The generator is electrically connected to the high-voltage side of the main transformer and the high-voltage side of the high-voltage auxiliary transformer through the generator outlet circuit breaker respectively. The low-voltage side of the main transformer is electrically connected to the bus unit through the first power supply unit. The bus unit is electrically connected to the first outgoing line unit and the second outgoing line unit. The bus unit is electrically connected to the high-voltage side of the high-voltage starting standby transformer through the second power supply unit. The low-voltage side of the high-voltage starting standby transformer is electrically connected to the first auxiliary low-voltage unit and the second auxiliary low-voltage unit. The low-voltage side of the high-voltage auxiliary transformer is electrically connected to the first auxiliary low-voltage unit and the second auxiliary low-voltage unit. The balance winding of the high-voltage starting standby transformer is connected to the high-voltage frequency conversion starting device through an outgoing line bushing. The high-voltage frequency conversion starting device is electrically connected to the generator.

[0006] Furthermore, the high-voltage starting standby transformer is a three-phase double-winding on-load tap-changing transformer. The high-voltage windings of the three-phase double-winding on-load tap-changing transformer have a total of one group, which is star-connected. The low-voltage windings have a total of one group, which is star-connected. The balance windings have a total of one group, which is delta-connected. The neutral point of the high-voltage winding is directly grounded. The neutral point of the low-voltage winding is grounded through a resistor cabinet. The high-voltage side of the high-voltage winding is connected to the bus unit through the second power supply unit. The low-voltage side winding is connected to the first auxiliary low-voltage unit and the second auxiliary low-voltage unit. The A, B, and C phases of the balance winding are led out through the outgoing line bushing to connect the terminal of the power supply of the high-voltage frequency conversion starting device.

[0007] Furthermore, the bus unit includes a first 220KV bus, a second 220KV bus, a first circuit breaker, a first isolating switch, and a second isolating switch. The first 220KV bus is connected to the second 220KV bus through the first isolating switch, the first circuit breaker, and the second isolating switch in sequence.

[0008] Further, the first power supply unit includes a second circuit breaker, a third isolating switch, a fourth isolating switch, and a fifth isolating switch. The second circuit breaker is connected to the third isolating switch, and the other end of the third isolating switch is connected to the high-voltage side of the main transformer. The other end of the second circuit breaker is respectively connected to one end of the fourth isolating switch and one end of the fifth isolating switch. The other end of the fourth isolating switch is connected to the first 220 kV bus, and the other end of the fifth isolating switch is connected to the second 220 kV bus. The second power supply unit includes a third circuit breaker, a sixth isolating switch, a seventh isolating switch, and an eighth isolating switch. One end of the third circuit breaker is connected to one end of the sixth isolating switch, and the other end of the sixth isolating switch is connected to the high-voltage side of the high-voltage start-up standby transformer. The other end of the third circuit breaker is respectively connected to one end of the seventh isolating switch and one end of the eighth isolating switch. The other end of the seventh isolating switch is connected to the first 220 kV bus, and the other end of the eighth isolating switch is connected to the second 220 kV bus.

[0009] Further, the first outgoing line unit includes a fourth circuit breaker, a ninth isolating switch, a tenth isolating switch, and an eleventh isolating switch. The fourth circuit breaker is connected to one end of the ninth isolating switch and one end of the tenth isolating switch. The other end of the ninth isolating switch is connected to the first 220 kV bus, and the other end of the tenth isolating switch is connected to the second 220 kV bus. The other end of the fourth circuit breaker is connected to one end of the eleventh isolating switch, and the other end of the eleventh isolating switch is connected to the external power grid. The second outgoing line unit includes a fifth circuit breaker, a twelfth isolating switch, a thirteenth isolating switch, and a fourteenth isolating switch. The fifth circuit breaker is connected to one end of the twelfth isolating switch and one end of the thirteenth isolating switch. The other end of the twelfth isolating switch is connected to the first 220 kV bus, and the other end of the thirteenth isolating switch is connected to the second 220 kV bus. The other end of the fifth circuit breaker is connected to one end of the fourteenth isolating switch, and the other end of the fourteenth isolating switch is connected to the external power grid.

[0010] Further, the first plant low-voltage unit includes a sixth circuit breaker, a seventh circuit breaker, and a 6KVA section of the machine plant. One end of the sixth circuit breaker is connected to the low-voltage side winding of the high-voltage start-up standby transformer, and one end of the seventh circuit breaker is connected to the low-voltage side of the high-voltage plant transformer. The other end of the sixth circuit breaker and the other end of the seventh circuit breaker are both connected to the 6KVA section of the machine plant; the second plant low-voltage unit includes an eighth circuit breaker, a ninth circuit breaker, and a 6KVB section of the machine plant. One end of the eighth circuit breaker is connected to the low-voltage side of the high-voltage plant transformer, and one end of the ninth circuit breaker is connected to the low-voltage side winding of the high-voltage start-up standby transformer. The other end of the eighth circuit breaker and the other end of the ninth circuit breaker are both connected to the 6KVB section of the machine plant.

[0011] Another object of the present invention is to provide a usage method that can better save energy for the power supply system of the high-voltage variable-frequency starting device of a gas turbine generator set.

[0012] A usage method for an energy-saving power supply system of a high-voltage variable-frequency starting device of a gas turbine generator set includes the following steps:

[0013] Step S1: Before the generator starts, disconnect the generator outlet circuit breaker;

[0014] Step S2: Close the sixth circuit breaker and the ninth circuit breaker. The high-voltage start-up standby transformer provides power for the high-voltage variable-frequency starting device, the first plant low-voltage unit, and the second plant low-voltage unit. Start the high-voltage variable-frequency starting device, and the high-voltage variable-frequency starting device starts the generator;

[0015] Step S3: When the high-voltage variable-frequency starting device drives the generator speed to reach about 2000 r.p.m, turn off the high-voltage variable-frequency starting device, and the shaft power output by the thermal turbine drives the generator to continue to increase speed;

[0016] Step S4: When the generator can reach the synchronous speed and can operate stably, close the generator outlet circuit breaker, and the generator supplies power to the bus unit;

[0017] Step S5: Close the seventh circuit breaker and the eighth circuit breaker and disconnect the sixth circuit breaker and the ninth circuit breaker. The high-voltage plant transformer provides power for the first plant low-voltage unit and the second plant low-voltage unit, and the high-voltage start-up standby transformer is changed to the hot standby state.

[0018] Advantages of the present invention: The present invention realizes the reduction of the capacity of the high-voltage auxiliary transformer, thereby reducing energy consumption, reducing the power supply nodes, and improving the power supply reliability; by providing power for the high-voltage frequency conversion starting device from the balance winding of the high-voltage start-up standby transformer, the capacity of the high-voltage auxiliary transformer is reduced, the cross-sections of the corresponding busbars and cables are reduced, thereby reducing the cost; at the same time, the power supply node of the 6kV section of the high-voltage auxiliary power section is reduced, and the power supply path of the high-voltage frequency conversion starting device is improved from "high-voltage start-up standby transformer - 6kV section of high-voltage auxiliary power section - high-voltage frequency conversion starting device" to "high-voltage start-up standby transformer - high-voltage frequency conversion starting device", reducing the power supply nodes and improving the power supply reliability. In the traditional scheme, the capacities of the high-voltage auxiliary transformer and the high-voltage start-up standby transformer are both 20MVA, and the capacity of the high-voltage frequency conversion starting device is 5MVA. The present invention can reduce the capacity of the high-voltage auxiliary transformer to 15MVA, saving the cost and improving the power supply reliability. Brief Description of the Drawings

[0019] Figure 1 is a schematic structural diagram of the present invention;

[0020] Figure 2 is a flowchart of the method of the present invention.

[0021] Among them, the high-voltage frequency conversion starting device 1, the main transformer 2, the high-voltage auxiliary transformer 3, the generator 4, the generator outlet circuit breaker 5, the high-voltage start-up standby transformer 6, the bus unit 7, the first power supply unit 8, the second power supply unit 9, the first outgoing line unit 10, the second outgoing line unit 11, the first auxiliary low-voltage unit 12, the second auxiliary low-voltage unit 13, the first 220KV busbar 71, the second 220KV busbar 72, the first circuit breaker 73, the first isolating switch 74, the second isolating switch 75, the second circuit breaker 81, the third isolating switch 82, the fourth isolating switch 83, the fifth isolating switch 84, the third circuit breaker 91, the sixth isolating switch 92, the seventh isolating switch 93, the eighth isolating switch 94, the fourth circuit breaker 101, the ninth isolating switch 102, the tenth isolating switch 103, the eleventh isolating switch 104, the fifth circuit breaker 111, the twelfth isolating switch 112, the thirteenth isolating switch 113, the fourteenth isolating switch 114, the sixth circuit breaker 121, the seventh circuit breaker 122, the 6KVA section of the auxiliary power of the machine 123, the eighth circuit breaker 131, the ninth circuit breaker 132, the 6KVB section of the auxiliary power of the machine 133. Detailed Embodiments

[0022] The present invention will be further described below with reference to the accompanying drawings.

[0023] Please refer to Figure 1, the present invention provides an embodiment: an energy-saving power supply system for a high-voltage variable-frequency starting device of a gas turbine generator set, including a high-voltage variable-frequency starting device 1, a main transformer 2, a high-voltage auxiliary transformer 3, a generator 4, a generator outlet circuit breaker 5, a high-voltage starting standby transformer 6, a bus unit 7, a first power supply unit 8, a second power supply unit 9, a first outgoing line unit 10, a second outgoing line unit 11, a first auxiliary low-voltage unit 12, and a second auxiliary low-voltage unit 13. The generator 4 is electrically connected to the low-voltage side of the main transformer 2 and the high-voltage side of the high-voltage auxiliary transformer 3 through the generator outlet circuit breaker 5. The high-voltage side of the main transformer 2 is electrically connected to the bus unit 7 through the first power supply unit 8. The bus unit 7 is electrically connected to the first outgoing line unit 10 and the second outgoing line unit 11. The bus unit 7 is electrically connected to the high-voltage side of the high-voltage starting standby transformer 6 through the second power supply unit 9. The low-voltage side of the high-voltage starting standby transformer 6 is electrically connected to the first auxiliary low-voltage unit 12 and the second auxiliary low-voltage unit 13. The low-voltage side of the high-voltage auxiliary transformer 3 is electrically connected to the first auxiliary low-voltage unit 12 and the second auxiliary low-voltage unit 13. The balance winding of the high-voltage starting standby transformer 6 is connected to the high-voltage variable-frequency starting device 1 through an outlet bushing. The high-voltage variable-frequency starting device 1 is electrically connected to the generator 4. The high-voltage variable-frequency starting device 1 is used to start the generator 4. The main transformer 2 is used to step up the electric energy generated by the generator 4 and transmit it to the bus unit 7. The high-voltage auxiliary transformer 3 steps down the electric energy generated by the generator 4 and transmits it to the first auxiliary low-voltage unit 12 and the second auxiliary low-voltage unit 13. The generator 4 is used to generate electricity for the power plant. The generator outlet circuit breaker 5 is used to cut off and connect the circuits between the generator 4 and the main transformer 2 and the high-voltage auxiliary transformer 3. The high-voltage starting standby transformer 6 is used to step down the voltage of the bus unit 7 and transmit it to the first auxiliary low-voltage unit 12 and the second auxiliary low-voltage unit 13 when the power plant is not generating electricity, and is also used to start the high-voltage variable-frequency starting device 1, so that it is not necessary to start through the high-voltage auxiliary transformer 3, thereby reducing the capacity of the high-voltage auxiliary transformer 3. The bus unit 7 is used to supply power to external power supply equipment. The first power supply unit 8 is used to connect and disconnect between the bus unit 7 and the main transformer 2. The second power supply unit 9 is used to connect and disconnect between the bus unit 7 and the high-voltage starting standby transformer 6. The first auxiliary low-voltage unit 12 and the second auxiliary low-voltage unit 13 are used to supply power to the auxiliary power distribution device.

[0024] Please continue to refer to Figure 1As shown, in an embodiment of the present invention, the high-voltage start-up standby transformer 6 is a three-phase double-winding on-load tap-changing transformer. The high-voltage windings of the three-phase double-winding on-load tap-changing transformer share one group, which is star-connected. The low-voltage windings share one group, which is star-connected. The balance windings share one group, which is delta-connected. The neutral point of the high-voltage winding is directly grounded. The neutral point of the low-voltage winding is grounded through a resistor cabinet. The high-voltage side winding is connected to the bus unit 7 through the second power supply unit 9. The low-voltage side winding is connected to the first plant low-voltage unit 12 and the second plant low-voltage unit 13. The A, B, and C phases of the balance windings lead out connection terminals through the outgoing bushing to be connected to the power supply of the high-voltage frequency conversion starting device 1. The function of the balance winding is to provide a triple-frequency harmonic path for the high-voltage start-up standby transformer 6 with star-connected high-voltage and low-voltage windings, eliminate the triple-harmonic magnetic flux, and thus eliminate the triple-harmonic components in the voltage. The capacity of the balance winding is usually 30% of the capacity of the high-voltage winding.

[0025] Please continue to refer to Figure 1 As shown, in an embodiment of the present invention, the bus unit 7 includes a first 220KV bus 71, a second 220KV bus 72, a first circuit breaker 73, a first isolating switch 74, and a second isolating switch 75. The first 220KV bus 71 is connected to the second 220KV bus 72 through the first isolating switch 74, the first circuit breaker 73, and the second isolating switch 75 in sequence. The first 220KV bus 71 and the second 220KV bus 72 are connected and disconnected through the first circuit breaker 73, the first isolating switch 74, and the second isolating switch 75. During normal operation, when the first 220KV bus 71 and the second 220KV bus 72 are connected, it can be seen as a 220KV bus. The bus unit 7 is of a double-bus connection type. The advantage of this connection type is that it can improve the power supply reliability, dispatching flexibility, and convenience of expansion and testing.

[0026] Please continue to refer to Figure 1As shown in the figure, in an embodiment of the present invention, the first power supply unit 8 includes a second circuit breaker 81, a third disconnecting switch 82, a fourth disconnecting switch 83, and a fifth disconnecting switch 84. The second circuit breaker 81 is connected to the third disconnecting switch 82. The other end of the third disconnecting switch 82 is connected to the high-voltage side of the main transformer 2. The other end of the second circuit breaker 81 is respectively connected to one end of the fourth disconnecting switch 83 and one end of the fifth disconnecting switch 84. The other end of the fourth disconnecting switch is connected to the first 220 kV bus 71, and the other end of the fifth disconnecting switch 84 is connected to the second 220 kV bus 72. The second power supply unit 9 includes a third circuit breaker 91, a sixth disconnecting switch 92, a seventh disconnecting switch 93, and an eighth disconnecting switch 94. One end of the third circuit breaker 91 is connected to one end of the sixth disconnecting switch 92. The other end of the sixth disconnecting switch 92 is connected to the high-voltage side of the high-voltage start-up standby transformer 6. The other end of the third circuit breaker 91 is respectively connected to one end of the seventh disconnecting switch 93 and one end of the eighth disconnecting switch 94. The other end of the seventh disconnecting switch 93 is connected to the first 220 kV bus 71, and the other end of the eighth disconnecting switch 94 is connected to the second 220 kV bus 72.

[0027] Please continue to refer to Figure 1 As shown in the figure, in an embodiment of the present invention, the first outgoing line unit 10 includes a fourth circuit breaker 101, a ninth disconnecting switch 102, a tenth disconnecting switch 103, and an eleventh disconnecting switch 104. The first outgoing line unit includes a fourth circuit breaker 101, a ninth disconnecting switch 102, a tenth disconnecting switch 103, and an eleventh disconnecting switch 104. The fourth circuit breaker 101 is connected to one end of the ninth disconnecting switch 102 and one end of the tenth disconnecting switch 103. The other end of the ninth disconnecting switch 102 is connected to the first 220 kV bus 71. The other end of the tenth disconnecting switch 103 is connected to the second 220 kV bus 72. The other end of the fourth circuit breaker 101 is connected to one end of the eleventh disconnecting switch 104, and the other end of the eleventh disconnecting switch 104 is connected to the external power grid. The second outgoing line unit 11 includes a fifth circuit breaker 111, a twelfth disconnecting switch 112, a thirteenth disconnecting switch 113, and a fourteenth disconnecting switch 114. The fifth circuit breaker 111 is connected to one end of the twelfth disconnecting switch 112 and one end of the thirteenth disconnecting switch 113. The other end of the twelfth disconnecting switch 112 is connected to the first 220 kV bus 71. The other end of the thirteenth disconnecting switch 113 is connected to the second 220 kV bus 72. The other end of the fifth circuit breaker 111 is connected to one end of the fourteenth disconnecting switch 114, and the other end of the fourteenth disconnecting switch 114 is connected to the external power grid. The number of outgoing line units is determined according to the scale of the power plant and the importance level of the power plant in the power grid. In specific projects, there may not necessarily be two circuits, and there may be more circuits.

[0028] Please continue to refer to Figure 1 As shown, in an embodiment of the present invention, the first plant low-voltage unit 12 includes a sixth circuit breaker 121, a seventh circuit breaker 122, and a plant auxiliary 6KVA section 123. One end of the sixth circuit breaker 121 is connected to the low-voltage side winding of the high-voltage start-up standby transformer 6, and one end of the seventh circuit breaker 122 is connected to the low-voltage side of the high-voltage plant transformer 3. The other end of the sixth circuit breaker 121 and the other end of the seventh circuit breaker 122 are both connected to the plant auxiliary 6KVA section 123. The second plant low-voltage unit 13 includes an eighth circuit breaker 131, a ninth circuit breaker 132, and a plant auxiliary 6KVB section 133. One end of the eighth circuit breaker 131 is connected to the low-voltage side of the high-voltage plant transformer 3, and one end of the ninth circuit breaker 132 is connected to the low-voltage side winding of the high-voltage start-up standby transformer 6. The other end of the eighth circuit breaker 131 and the other end of the ninth circuit breaker 132 are both connected to the plant auxiliary 6KVB section 133. The plant auxiliary 6KVA section 123 and the plant auxiliary 6KVB section 133 are used to connect in-plant electrical equipment.

[0029] Please continue to refer to Figure 2 As shown, a method for using an energy-saving power supply system of a high-voltage variable-frequency starting device for a gas turbine generator set includes the following steps:

[0030] Step S1: Before the generator starts, disconnect the generator outlet circuit breaker;

[0031] Step S2: Close the sixth circuit breaker and the ninth circuit breaker. The high-voltage start-up standby transformer provides power for the high-voltage variable-frequency starting device, the first plant low-voltage unit, and the second plant low-voltage unit, and start the high-voltage variable-frequency starting device. The high-voltage variable-frequency starting device starts the generator;

[0032] Step S3: When the high-voltage variable-frequency starting device drives the generator speed to reach about 2000 r.p.m, turn off the high-voltage variable-frequency starting device, and the shaft power output by the thermal turbine drives the generator to continue to increase speed;

[0033] Step S4: When the generator can reach the synchronous speed and can operate stably, close the generator outlet circuit breaker, and the generator supplies power to the bus unit;

[0034] Step S5: Close the seventh circuit breaker and the eighth circuit breaker and disconnect the sixth circuit breaker and the ninth circuit breaker. The high-voltage plant transformer provides power for the first plant low-voltage unit and the second plant low-voltage unit, and the high-voltage start-up standby transformer is changed to the hot standby state.

[0035] The high-voltage frequency conversion starting device, main transformer, high-voltage auxiliary transformer, generator, generator outlet circuit breaker, and high-voltage start-up standby transformer in the present invention are all prior arts, and those skilled in the art have been able to clearly understand them, so no detailed description will be given here.

[0036] The above are only the preferred embodiments of the present invention, and should not be construed as limitations to this application. Any equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims

1. A method of using an energy-saving power supply system for a high-voltage variable-frequency starting device of a gas turbine generator set, characterized in that, The energy-saving power supply system of the high-voltage frequency conversion starting device for a gas turbine generator set includes a high-voltage frequency conversion starting device, a main transformer, a high-voltage auxiliary transformer, a generator, a generator outlet circuit breaker, a high-voltage starting standby transformer, a bus unit, a first power supply unit, a second power supply unit, a first outgoing line unit, a second outgoing line unit, a first auxiliary low-voltage unit, and a second auxiliary low-voltage unit. The generator is electrically connected to the low-voltage side of the main transformer and the high-voltage side of the high-voltage auxiliary transformer through the generator outlet circuit breaker. The high-voltage side of the main transformer is electrically connected to the bus unit through the first power supply unit. The bus unit is electrically connected to the first outgoing line unit and the second outgoing line unit. The bus unit is electrically connected to the high-voltage side of the high-voltage starting standby transformer through the second power supply unit. The low-voltage side of the high-voltage starting standby transformer is electrically connected to the first auxiliary low-voltage unit and the second auxiliary low-voltage unit. The low-voltage side of the high-voltage auxiliary transformer is electrically connected to the first auxiliary low-voltage unit and the second auxiliary low-voltage unit. The balance winding of the high-voltage starting standby transformer is connected to the high-voltage frequency conversion starting device through an outgoing line bushing. The high-voltage frequency conversion starting device is electrically connected to the generator. The first auxiliary low-voltage unit includes a sixth circuit breaker, a seventh circuit breaker, and a 6KVA section for the generator auxiliary. One end of the sixth circuit breaker is connected to the low-voltage winding of the high-voltage starting standby transformer. One end of the seventh circuit breaker is connected to the low-voltage side of the high-voltage auxiliary transformer. The other end of the sixth circuit breaker and the other end of the seventh circuit breaker are both connected to the 6KVA section for the generator auxiliary. The second auxiliary low-voltage unit includes an eighth circuit breaker, a ninth circuit breaker, and a 6KVB section for the generator auxiliary. One end of the eighth circuit breaker is connected to the low-voltage side of the high-voltage auxiliary transformer. One end of the ninth circuit breaker is connected to the low-voltage winding of the high-voltage starting standby transformer. The other end of the eighth circuit breaker and the other end of the ninth circuit breaker are both connected to the 6KVB section for the generator auxiliary. The usage method includes the following steps: Step S1: Before starting the generator, disconnect the generator outlet circuit breaker. Step S2: Close the sixth circuit breaker and the ninth circuit breaker. The high-voltage starting standby transformer provides power for the high-voltage frequency conversion starting device, the first auxiliary low-voltage unit, and the second auxiliary low-voltage unit. Start the high-voltage frequency conversion starting device, and the high-voltage frequency conversion starting device starts the generator. Step S3: When the high-voltage frequency conversion starting device drives the generator speed to reach 2000 r.p.m, turn off the high-voltage frequency conversion starting device, and the shaft power output by the thermal turbine drives the generator to continue to increase speed. Step S4: When the generator can reach the synchronous speed and can operate stably, close the generator outlet circuit breaker, and the generator supplies power to the bus unit. Step S5: Close the seventh circuit breaker and the eighth circuit breaker and disconnect the sixth circuit breaker and the ninth circuit breaker. The high-voltage auxiliary transformer provides power for the first auxiliary low-voltage unit and the second auxiliary low-voltage unit, and the high-voltage starting standby transformer is changed to the hot standby state.

2. The usage method of an energy-saving power supply system for a high-voltage frequency conversion starting device of a gas turbine generator set according to claim 1, characterized in that: The high-voltage start-up standby transformer is a three-phase double-winding on-load tap-changing transformer. The high-voltage windings of the three-phase double-winding on-load tap-changing transformer form a single group, which is star-connected. The low-voltage windings form a single group, which is star-connected. The balance windings form a single group, which is delta-connected. The neutral point of the high-voltage winding is directly grounded. The neutral point of the low-voltage winding is grounded through a resistor cabinet. The high-voltage side of the high-voltage winding is connected to the bus unit through the second power supply unit. The low-voltage winding is connected to the first low-voltage unit for plant use and the second low-voltage unit for plant use. The A, B, and C phases of the balance windings are led out through the outgoing bushing to connect the terminal to the power supply connection of the high-voltage frequency conversion starting device.

3. The usage method of an energy-saving power supply system for a high-voltage variable-frequency starting device of a gas turbine generator set according to claim 1, characterized in that: The bus unit includes a first 220 kV bus, a second 220 kV bus, a first circuit breaker, a first isolating switch, and a second isolating switch. The first 220 kV bus is connected to the second 220 kV bus through the first isolating switch, the first circuit breaker, and the second isolating switch in sequence.

4. A method for using an energy-saving power supply system of a high-voltage variable-frequency starting device for a gas turbine generator set according to claim 3, characterized in that: The first power supply unit includes a second circuit breaker, a third isolating switch, a fourth isolating switch, and a fifth isolating switch. The second circuit breaker is connected to the third isolating switch. The other end of the third isolating switch is connected to the high-voltage side of the main transformer. The other end of the second circuit breaker is respectively connected to one end of the fourth isolating switch and one end of the fifth isolating switch. The other end of the fourth isolating switch is connected to the first 220 kV bus. The other end of the fifth isolating switch is connected to the second 220 kV bus. The second power supply unit includes a third circuit breaker, a sixth isolating switch, a seventh isolating switch, and an eighth isolating switch. One end of the third circuit breaker is connected to one end of the sixth isolating switch. The other end of the sixth isolating switch is connected to the high-voltage side of the high-voltage start-up standby transformer. The other end of the third circuit breaker is respectively connected to one end of the seventh isolating switch and one end of the eighth isolating switch. The other end of the seventh isolating switch is connected to the first 220 kV bus. The other end of the eighth isolating switch is connected to the second 220 kV bus.

5. The usage method of an energy-saving power supply system for a high-voltage frequency conversion starting device of a gas turbine generator set according to claim 3, characterized in that: The first outgoing line unit includes a fourth circuit breaker, a ninth isolating switch, a tenth isolating switch, and an eleventh isolating switch. The fourth circuit breaker is connected to one end of the ninth isolating switch and one end of the tenth isolating switch. The other end of the ninth isolating switch is connected to the first 220 kV busbar, and the other end of the tenth isolating switch is connected to the second 220 kV busbar. The other end of the fourth circuit breaker is connected to one end of the eleventh isolating switch, and the other end of the eleventh isolating switch is connected to the external power grid. The second outgoing line unit includes a fifth circuit breaker, a twelfth isolating switch, a thirteenth isolating switch, and a fourteenth isolating switch. The fifth circuit breaker is connected to one end of the twelfth isolating switch and one end of the thirteenth isolating switch. The other end of the twelfth isolating switch is connected to the first 220 kV busbar, and the other end of the thirteenth isolating switch is connected to the second 220 kV busbar. The other end of the fifth circuit breaker is connected to one end of the fourteenth isolating switch, and the other end of the fourteenth isolating switch is connected to the external power grid.

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