Power system and its generator set start-stop power supply system

Abstract

The utility model discloses a power system and generator set start -stop power supply system. Generator set start -stop power supply system includes: start -stop power supply transformer adopts three -phase split winding transformer, and the high voltage side of start -stop power supply transformer is introduced from the separation of phase closed busbar between the low voltage side and outlet circuit breaker of main transformer, and the high voltage side of start -stop power supply transformer adopts star connection, and the neutral point of star connection is grounded through the first resistance cabinet, protection device is coupled with first resistance cabinet, and the current that flows through first resistance cabinet is acquired, and protection device still is coupled with the distribution device of main transformer high voltage side, when the current of first resistance cabinet exceeds the preset current threshold value, controls distribution device and main transformer are disconnected. The above -mentioned power system and generator set start -stop power supply system can effectively protect the damage of generator set from the single -phase ground fault of separation of phase closed busbar.

Description

Technical Field

[0001] This utility model relates to the field of high-voltage power generation technology, and in particular to a power system and its generator set start-stop power supply system. Background Technology

[0002] A generator output circuit breaker (GCB) is typically installed between large generators and main transformers. The power supply for the high-voltage station service transformer is drawn from the isolated phase busbar between the low-voltage side of the main transformer and the generator output circuit breaker. The traditional winding connection of the high-voltage station service transformer is D, yn1, yn1, and the high-voltage side is ungrounded. The generator neutral point is grounded via a resistor on the secondary side of the distribution transformer. When a single-phase ground fault occurs in the generator output circuit, the generator output circuit breaker trips instantaneously, protecting the safe operation of the unit. The advantages of this scheme are simple and clear wiring, simple relay protection, convenient operation and maintenance, and rich operating experience. The vast majority of power projects in China adopt this scheme.

[0003] The startup process of large generator sets is complex, involves multiple starting loads, and is lengthy, typically requiring 1-2 days for a cold start. Furthermore, the large installed capacity of the domestic power grid necessitates that all large generator sets connected to the grid possess peak-shaving capabilities, leading to frequent start-ups and shutdowns in the later stages of operation. During generator startup, the generator's output circuit breaker is disconnected. Traditional high-voltage station transformers, with their conventional winding connections, are prone to voltage oscillations that can propagate to the power grid and cause various damages when a single-phase ground fault occurs on the isolated phase busbar. Utility Model Content

[0004] Therefore, it is necessary to provide a power system and its generator set start-up and shutdown power supply system and start-up and shutdown power supply control method to address the problem of damage caused by a single-phase ground fault in an isolated phase bus.

[0005] A generator set start-stop power supply system is provided for use as a power source during generator set startup and shutdown. The generator set is coupled to the low-voltage side of the main transformer via an output circuit breaker. The generator set start-stop power supply system includes:

[0006] The start-stop power supply transformer is a three-phase split-winding transformer; the high-voltage side of the start-stop power supply transformer is led from the phase-separated closed bus between the low-voltage side of the main transformer and the outlet circuit breaker, and the high-voltage side of the start-stop power supply transformer adopts a star connection, and the neutral point of the star connection is grounded through the first resistor cabinet.

[0007] The protection device is coupled to the first resistor cabinet to obtain the current flowing through the first resistor cabinet; the protection device is also coupled to the power distribution device on the high-voltage side of the main transformer, and when the current of the first resistor cabinet exceeds a preset current threshold, it controls the power distribution device to disconnect from the main transformer.

[0008] In one embodiment, the three-phase split windings on the low-voltage side of the start-stop power transformer are a first low-voltage split winding, a second low-voltage split winding, and an additional low-voltage winding.

[0009] The first low-voltage split winding adopts a star connection and the neutral point is grounded through the first grounding resistor, and the voltage phase is the same as the voltage phase of the high-voltage side;

[0010] The second low-voltage split winding adopts a star connection and the neutral point is grounded through the second grounding resistor, and the voltage phase is the same as the voltage phase of the high-voltage side;

[0011] The additional low-voltage winding adopts a delta connection and its voltage phase lags the high-voltage side voltage phase by 330°.

[0012] In one embodiment, the resistance of the first resistor cabinet is 120~140 ohms.

[0013] In one embodiment, the resistance of the first resistor cabinet is 130 ohms.

[0014] In one embodiment, the number of start-stop power transformers is two or more.

[0015] In one embodiment, the protection device independently monitors the start-stop power supply system, and when the current of any of the start-stop power supply transformers exceeds a preset current threshold, it controls the corresponding power distribution device to disconnect from the main transformer.

[0016] An electric power system, comprising:

[0017] Generator sets are used to generate electricity;

[0018] The main transformer is coupled to the generator set and increases the output voltage of the generator set before transmitting it to the power distribution equipment.

[0019] Power distribution equipment is used to transmit the voltage output from the main transformer to the power grid;

[0020] An output circuit breaker is connected between the generator set and the main transformer;

[0021] The start-stop power supply system, as described above, is used as the power source for starting and stopping the generator set.

[0022] In one embodiment, it further includes: a generator neutral point grounding transformer; the generator set is grounded through the generator neutral point grounding transformer.

[0023] In one embodiment, the power distribution device uses a 3 / 2 circuit breaker connection.

[0024] In one embodiment, the main transformer is a 500 kV transformer.

[0025] The aforementioned power system and its generator start-stop power supply system can effectively protect the generator from damage caused by single-phase grounding faults on the isolated busbar that may occur during frequent start-stop processes. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a power system structure according to one embodiment;

[0027] Figure 2 This is a flowchart of a generator set start-stop power control method according to one embodiment. Detailed Implementation

[0028] To facilitate understanding of this utility model, a more complete description will be given below with reference to the accompanying drawings. The drawings illustrate preferred embodiments of this utility model. However, this utility model can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of this utility model more thorough and complete.

[0029] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0030] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0031] This application provides a power system. The power system includes: a generator set 100, an output circuit breaker 500, a main transformer 200, a power distribution unit 300, and a start-stop power supply system 400. The generator set 100 is used to generate electricity. The main transformer 200 is coupled to the generator set 100, increasing the output voltage of the generator set 100 before transmitting it to the power distribution unit 300. The power distribution unit 300 is used to transmit the voltage output by the main transformer 200 to the power grid. The output circuit breaker 500 is connected between the generator set 100 and the main transformer 200. The start-stop power supply system 400 serves as the power source for starting and stopping the generator set 100.

[0032] Generator set 100 is a device that converts other forms of energy (such as chemical energy, hydropower, and nuclear energy) into electrical energy. In large thermal power plants or nuclear power plants, the mainstream generator set 100 is usually a synchronous generator, whose working principle is based on the law of electromagnetic induction: a prime mover (such as a steam turbine or water turbine) drives the rotor to rotate, causing the rotating magnetic field generated by the rotor's excitation winding to cut the stator winding, thereby inducing a three-phase alternating electromotive force in the stator winding, realizing the conversion of mechanical energy into electrical energy. The operating state of generator set 100 needs to be dynamically matched with the grid load. When the grid load increases, the prime mover needs to increase the input power to synchronously increase the generator output power; when the load decreases, the input power needs to decrease. Large generator sets 100 connected to the grid system are required to have peak-shaving capabilities, therefore, generator sets 100 experience frequent start-ups and shutdowns in later stages of operation.

[0033] The main transformer 200 is a key device connecting the generator set 100 to the high-voltage power grid. It steps up the medium- and low-voltage electrical energy (10kV-25kV) output from the generator set 100 to high-voltage or ultra-high-voltage (such as 110kV, 220kV, 500kV, and 1000kV) to reduce power transmission losses and meet the needs of long-distance power transmission. The main transformer 200 consists of an iron core and high- and low-voltage windings, with the high-voltage winding having significantly more turns than the low-voltage winding. When the low-voltage winding is connected to the output voltage of the generator set 100, an alternating magnetic flux is generated in the iron core, inducing a high voltage in the high-voltage winding, thus achieving voltage level conversion. The end with the high-voltage winding is called the high-voltage side, and the end with the low-voltage winding is called the low-voltage side.

[0034] The power distribution unit 300 is a collection of equipment for receiving, distributing, and controlling electrical energy. The power distribution unit 300 distributes the high-voltage electrical energy (e.g., 500kV) boosted by the main transformer 200 to different transmission lines, transmitting it to the power grid or regional load centers, while simultaneously monitoring, protecting, and isolating the electrical energy. The power distribution unit 300 may include circuit breakers, disconnect switches, instrument transformers (current transformers, voltage transformers), busbars, etc. Based on voltage level, it can be divided into high-voltage power distribution units (e.g., 500kV power distribution units) and medium-voltage power distribution units (e.g., 110kV power distribution units). In one embodiment, the main transformer 200 is a 500kV transformer. Correspondingly, the 500kV power distribution unit 300 adopts a 3 / 2 circuit breaker connection method, meaning that two transmission lines share three circuit breakers. Even if one circuit breaker fails, both lines can still supply power normally, significantly improving power supply reliability.

[0035] The 500kV power, stepped up by the main transformer 200, is connected to the busbar of the distribution unit 300, and then distributed to multiple 500kV transmission lines via circuit breakers and disconnectors in the distribution unit 300, reaching the regional power grid or load center. For example, a 500kV distribution unit 300 may use a 3 / 2 circuit breaker connection, where two transmission lines share three circuit breakers. Even if one circuit breaker fails, both lines can still supply power normally, improving power supply reliability.

[0036] The output circuit breaker 500 connects the generator set 100 and the main transformer 200, and is a device for controlling the connection and disconnection of the generator set 100 and the power grid, as well as isolating faults. The output circuit breaker 500 is a high-voltage switching device that achieves circuit connection and disconnection through the opening and closing of contacts. It also has an arc-extinguishing function, quickly extinguishing the electric arc generated between the contacts when the high-voltage circuit is disconnected, preventing arc erosion of the contacts or insulation damage. During normal operation of the unit, the circuit breaker can be closed to allow power transmission from the generator set 100 to the main transformer 200. When the unit is shut down or under maintenance, the circuit breaker can be opened to isolate the generator set 100 from the power grid, ensuring the safety of maintenance personnel. In the event of a fault in the power grid or the generator set, the output circuit breaker 500 can be quickly tripped to prevent the fault from spreading to the generator set 100 or other equipment.

[0037] The start-stop power supply system 400 provides auxiliary power for the generator set 100 during startup, shutdown, and emergency operation. When the generator set 100 is not generating electricity or has stopped, it supplies power to the unit's auxiliary equipment (such as the lubricating oil pump, cooling water pump, and excitation system) to ensure smooth startup and safe shutdown. For large generator sets, the start-stop power supply system 400 typically uses a high-voltage station service transformer as its core, in conjunction with a low-voltage station service transformer and an automatic transfer switch for backup power. The high-voltage station service transformer is usually powered by the isolated busbar between the low-voltage side of the main transformer 200 and the outlet circuit breaker 500. The start-stop power supply system 400 can use dual or multiple power sources (such as two high-voltage station service transformers, one for operation and one for backup) to prevent power loss to auxiliary equipment due to a single power source failure. During the startup phase of the generator set 100 (before ignition and power generation), the start-stop power supply system 400 supplies power to the excitation system through the high-voltage station service transformer, enabling the generator to establish an excitation magnetic field; simultaneously, it supplies power to the cooling water pump, providing cooling water to the turbine. During the shutdown phase of generator set 100, the start-stop power supply system 400 needs to continuously supply power to the lubricating oil pump until the turbine rotor comes to a complete stop, in order to prevent the rotor from wearing due to lack of lubricating oil.

[0038] Traditional high-voltage station service transformers have a winding connection of (D, yn1, yn1), with the high-voltage side ungrounded. Here, D represents a delta connection for the high-voltage winding, and the two yn1s represent two low-voltage windings, both connected in a star configuration with a neutral ground. With this connection, if a single-phase ground fault occurs in the isolated-phase busbar circuit from the low-voltage side of the main transformer 200 to the high-voltage side of the high-voltage station service transformer, and the grounding capacitance current is small enough not to form a stable arc, an unstable arc may occur, causing instantaneous changes in the grid's operating state and resulting in intermittent arc grounding overvoltage. The interaction between this intermittent grounding overvoltage and the grid oscillation circuit can cause resonant overvoltage. This resonant overvoltage can reach 2.5 to 3 times the phase voltage, leading to insulation breakdown of normal phases, forming a phase-to-phase short circuit, and burning out the isolated-phase busbar conductors. In severe cases, it can also damage the connected output circuit breaker 500, the main transformer 200, or the high-voltage station service transformer.

[0039] To prevent resonant overvoltage caused by a single-phase ground fault in the isolated phase busbar circuit, a start-stop power supply system 400 according to an embodiment of this application includes a start-stop power supply transformer 402 and a protection device 412. The start-stop power supply transformer 402 is a three-phase split-winding transformer; the high-voltage side of the start-stop power supply transformer 402 is connected from the isolated phase busbar between the low-voltage side of the main transformer 200 and the output circuit breaker 500, and the high-voltage side of the start-stop power supply transformer 402 is star-connected, with the neutral point of the star connection grounded through a first resistor cabinet 404. The protection device 412 is coupled to the first resistor cabinet 404 to obtain the current flowing through it. The protection device 412 is also coupled to the power distribution device 300 on the high-voltage side of the main transformer 200; when the current in the first resistor cabinet 404 exceeds a preset current threshold, it controls the power distribution device 300 to disconnect from the main transformer 200.

[0040] A three-phase split-winding transformer has two or more low-voltage windings wound on each phase core column of a three-phase core, in addition to one high-voltage winding. These split windings are electrically independent of each other. Essentially, it integrates two or more transformers with ordinary low-voltage windings onto a single core and high-voltage winding, enabling it to simultaneously output multiple independent low-voltage power supplies from a single high-voltage power source.

[0041] The start-stop power transformer 402 can be a high-voltage auxiliary transformer for high-voltage plants. Its high-voltage side is connected in a star configuration, and the neutral point of this star connection is grounded through the first resistor cabinet 404. When a single-phase ground fault occurs on the isolated busbar between the low-voltage side of the main transformer 200 and the high-voltage side of the high-voltage auxiliary transformer, if a resonant overvoltage occurs, a large resistive-capacitive current can flow through the protection device 412 due to its coupling with the first resistor cabinet 404. Based on this large current, the protection device 412 can perform protective actions, disconnecting the main transformer 200 from the power grid to prevent further fault expansion. After the grounded neutral point on the high-voltage side of the high-voltage auxiliary transformer is connected to the first resistor cabinet 404, a resistive current can be injected into the fault point. The resistive component of this current is 1.05-1.1 times the capacitive component. This limits the fault current to a moderate level, improves the sensitivity of the relay protection, and ensures that only minor local damage may occur at the fault point, limiting transient overvoltage to 2.6 times the normal voltage relative to the neutral point.

[0042] The aforementioned start-stop power supply system 400 effectively protects generator set 100 from damage caused by single-phase grounding faults on the isolated busbar during frequent start-stop operations. For a large generator set: the first resistor cabinet 404 at the neutral point of the high-voltage side of one high-voltage station service transformer costs approximately 100,000 RMB, two units total 200,000 RMB; one main transformer costs approximately 30 million RMB, two high-voltage station service transformers approximately 13 million RMB; one outgoing circuit breaker costs approximately 10 million RMB, and the isolated busbar on the station service branch costs approximately 400,000 RMB; the total is approximately 53.4 million RMB. Typically, power engineering projects involve the construction of two units, totaling 106.8 million RMB, representing a significant investment and high cost. For a power project constructing two units, only four resistor cabinets need to be added, costing approximately 400,000 RMB each. In the event of a fault, the grounding current flowing through the protection device 412 increases, allowing the protection device 412 to quickly and sensitively disconnect the high-voltage side of the main transformer 200 from the power grid, interrupting the fault current. This can prevent a series of subsequent faults from spreading, thereby protecting equipment such as the phase-separated busbar equipment, the 500-phase circuit breaker, the high-voltage plant transformer, and the 200-phase main transformer, resulting in significant economic benefits.

[0043] In some embodiments, the three-phase split windings on the low-voltage side of the start-stop power transformer 402 are a first low-voltage split winding 406, a second low-voltage split winding 408, and an additional low-voltage winding 410. The first low-voltage split winding 406 is star-connected with its neutral point grounded through a first grounding resistor, and its voltage phase is the same as the high-voltage side voltage phase; the second low-voltage split winding 408 is star-connected with its neutral point grounded through a second grounding resistor, and its voltage phase is the same as the high-voltage side voltage phase; the additional low-voltage winding 410 is delta-connected with its voltage phase lagging behind the high-voltage side voltage phase by 330°.

[0044] The start-stop power transformer 402 uses a (YN, yn0, yn0, +d11) connection.

[0045] Connection method Y / y indicates a star connection, where one end of the three-phase windings is connected together, and the other end is connected to the three-phase power supply / load; D / d indicates a delta connection, where the three-phase windings are connected end-to-end to form a closed delta. Uppercase letters indicate the connection method on the high-voltage side, and lowercase letters indicate the connection method on the low-voltage side. N / n indicates that the neutral point is grounded.

[0046] Polarity group The phase relationship between the high-voltage and low-voltage windings is represented by numbers such as 0 and 11. The numbers correspond to the angle by which the low-voltage winding voltage lags the high-voltage winding voltage (e.g., 0 indicates they are in phase, "11" indicates a 330° lag). It can also be understood by comparing it to the position of a clock hand.

[0047] Therefore, YN represents the connection method of the high-voltage side winding of the high-voltage station service transformer, indicating a star connection with the neutral point grounded. After connecting the grounded neutral point of the high-voltage side of the high-voltage station service transformer to the first resistor cabinet 404, resistive current can be injected into the fault point. The resistive component of the current is 1.05-1.1 times the capacitive component of the current. This can limit the fault current to a moderate level, improve the sensitivity of relay protection, and ensure that only minor local damage may occur at the fault point, limiting transient overvoltage to 2.6 times the normal relative neutral point voltage.

[0048] The first yn0 indicates the connection method of the first low-voltage split winding 406, meaning that the first low-voltage split winding 406 adopts a star connection and the neutral point is grounded through the first grounding resistor, and the voltage phase is the same as the voltage phase of the high-voltage side.

[0049] The second yn0 indicates the connection method of the second low-voltage split winding 408, meaning that the second low-voltage split winding 408 adopts a star connection and the neutral point is grounded through the second grounding resistor, and the voltage phase is the same as the voltage phase of the high-voltage side.

[0050] The two yn0 windings have symmetrical parameters and consistent phase, which can be used to supply power to two independent plant loads. The neutral point grounding can ensure the safety of personnel and equipment on the low-voltage side.

[0051] +d11 indicates the connection method of the additional low-voltage winding 410, meaning that the additional low-voltage winding 410 adopts a delta connection and its voltage phase lags behind the high-voltage side voltage phase by 330°. The function of the additional low-voltage winding 410 is generally to absorb third harmonics (such as the 3rd, 9th, and 15th harmonics) in the power grid, avoid voltage distortion on the low-voltage side caused by harmonics, protect sensitive equipment (such as motors and frequency converters), and also improve the operating stability of the transformer.

[0052] In some embodiments, the resistance of the first resistor cabinet 404 is 120~140 ohms. Specifically, the resistance of the first resistor cabinet 404 can be 130 ohms. When a single-phase ground fault occurs on the conductor of the isolated phase busbar from the low-voltage side of the main transformer 200 to the high-voltage side of the high-voltage station service transformer, the resistive-capacitive current flowing through the protection device 412 is about 100A, which improves the sensitivity and selectivity of the grounding protection.

[0053] In one embodiment, such as Figure 1 As shown, the power system may also include a generator neutral point grounding transformer 600. The generator set is grounded through the generator neutral point grounding transformer 600. The generator neutral point grounding transformer 600 is used to limit the magnitude of the single-phase ground fault current when a single-phase ground fault occurs in the stator winding of the generator set 100, thereby ensuring the safe operation of the generator set 100.

[0054] In one embodiment, when there are two or more start-stop power transformers 402, multiple power outputs can be provided, or for backup purposes. The protection device 412 independently monitors the start-stop power system 400. When the current of any of the start-stop power transformers 402 exceeds a preset current threshold, it controls the corresponding power distribution device 300 to disconnect from the main transformer 200. Two sets of protection devices 412 can monitor the current of their respective start-stop power transformers 402, or one set of protection devices 412 can centrally monitor the current of multiple start-stop power transformers 402. The solution is flexible.

[0055] Based on the same utility model concept, such as Figure 2 As shown, this application provides a generator set start-stop power control method, applied to the aforementioned power system. Combined with... Figure 1 The method includes:

[0056] S102: Disconnect the output circuit breaker 500. The output circuit breaker 500 achieves circuit connection and disconnection through the opening and closing of its contacts. When the generator set 100 is in the startup process, the output circuit breaker 500 can be disconnected to isolate the generator set 100 from the power grid.

[0057] S104: The main transformer 200 inputs three-phase voltage to the high-voltage side of the start-stop power transformer 402 through the phase-separated enclosed busbar. Since the generator set 100 has not yet started, the start-stop power transformer 402 draws power through the phase-separated enclosed busbar between the generator set 100 and the output circuit breaker 500. At this time, electrical energy is transmitted (reverse transmission) from the high-voltage side to the low-voltage side by the main transformer 200.

[0058] S106: Detect the current flowing through the first resistor cabinet 404. When the current in the first resistor cabinet 404 exceeds a preset current threshold, control the power distribution device 300 to disconnect. According to the above structure, the high-voltage side of the high-voltage station service transformer adopts a star connection, and the neutral point is grounded through the first resistor cabinet 404. When a single-phase ground fault occurs on the isolated closed busbar from the low-voltage side of the main transformer 200 to the high-voltage side of the high-voltage station service transformer, if a resonant overvoltage occurs, the first resistor cabinet 404 can inject resistive current into the fault point. The resistive component current is 1.05-1.1 times the capacitive component current. This can limit the fault current to a suitable level and improve the sensitivity of the relay protection. Since the protection device 412 is coupled to the first resistor cabinet 404, a large resistive-capacitive current can be obtained flowing through the protection device 412. Based on this large current, the protection device 412 can perform a protection action, disconnecting the main transformer 200 and the power grid to prevent the fault from further expanding.

[0059] S108: After the generator set 100 starts successfully, close the output circuit breaker 500. After the generator set 100 starts normally, the output circuit breaker 500 can be closed to allow the generator set 100 to transmit electrical energy to the main transformer 200.

[0060] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0061] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A generator set start-stop power supply system, used as a power source for starting and stopping a generator set, wherein the generator set is coupled to the low-voltage side of a main transformer via an output circuit breaker, and the generator set start-stop power supply system comprises: The start-stop power supply transformer is a three-phase split-winding transformer. The high-voltage side of the start-stop power supply transformer is led from the phase-separated closed bus between the low-voltage side of the main transformer and the outlet circuit breaker, and the high-voltage side of the start-stop power supply transformer adopts a star connection, with the neutral point of the star connection grounded through the first resistor cabinet. The protection device is coupled to the first resistor cabinet to obtain the current flowing through the first resistor cabinet; the protection device is also coupled to the power distribution device on the high-voltage side of the main transformer, and when the current of the first resistor cabinet exceeds a preset current threshold, it controls the power distribution device to disconnect from the main transformer.

2. The generator set start-stop power supply system according to claim 1, characterized in that, The three-phase split windings on the low-voltage side of the start-stop power transformer are the first low-voltage split winding, the second low-voltage split winding, and the additional low-voltage winding. The first low-voltage split winding adopts a star connection and the neutral point is grounded through the first grounding resistor, and the voltage phase is the same as the voltage phase of the high-voltage side; The second low-voltage split winding adopts a star connection and the neutral point is grounded through the second grounding resistor, and the voltage phase is the same as the voltage phase of the high-voltage side; The additional low-voltage winding adopts a delta connection and its voltage phase lags the high-voltage side voltage phase by 330°.

3. The generator set start-stop power supply system according to claim 1, characterized in that, The resistance of the first resistor cabinet is 120~140 ohms.

4. The generator set start-stop power supply system according to claim 1, characterized in that, The resistance of the first resistor cabinet is 130 ohms.

5. The generator set start-stop power supply system according to claim 1, characterized in that, The number of start-stop power supply transformers is two or more.

6. The generator set start-stop power supply system according to claim 5, characterized in that, The protection devices independently monitor the start-stop power supply system. When the current of any of the start-stop power supply transformers exceeds a preset current threshold, the corresponding power distribution device is controlled to disconnect from the main transformer.

7. An electric power system, characterized in that, include: Generator sets are used to generate electricity; The main transformer is coupled to the generator set and increases the output voltage of the generator set before transmitting it to the power distribution equipment. Power distribution equipment is used to transmit the voltage output from the main transformer to the power grid; An output circuit breaker is connected between the generator set and the main transformer; The start-stop power supply system is the start-stop power supply system according to any one of claims 1 to 6, used as a power supply for the generator set during startup and shutdown.

8. The power system according to claim 7, characterized in that, Also includes: The generator set is grounded through the generator neutral point grounding transformer.

9. The power system according to claim 7, characterized in that, The power distribution device uses a 3 / 2 circuit breaker connection.

10. The power system according to claim 7, characterized in that, The main transformer is a 500 kV transformer.

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