A device and method for using thermal power plants to store and supply power to power plants

Abstract

The application discloses a device and method for using thermal power plant to store and supply power, and relates to the technical field of power system automation. The device comprises an energy storage system, a fast switching device and a controller. The energy storage system is connected to a plant power bus through an energy storage converter PCS and an energy storage access switch. The fast switching device is connected between a working power supply switch and the energy storage access switch. The controller is connected to the energy storage converter PCS and the fast switching device. The controller controls the energy storage converter PCS to establish a bus voltage in a VF network mode and maintain a hot standby voltage building state under specific conditions. When the controller receives a trip signal and determines that the working power supply switch has tripped, the controller controls the fast switching device to disconnect the working power supply switch and turn on the energy storage access switch, thereby realizing uninterrupted and rapid switching of plant power. The energy storage serves as a bottom backup power supply during the startup of a standby transformer, thereby effectively improving the power supply reliability of plant power in thermal power plants.

Description

Technical Field

[0001] This invention relates to the field of power system automation technology, specifically to a device and method for utilizing the power distribution, storage and protection of power plants in thermal power plants. Background Technology

[0002] Thermal power plant auxiliary power systems typically employ a "dual power supply" architecture. During normal operation, the high-voltage auxiliary transformer (VVT) draws power from the generator output and supplies it to the auxiliary power bus via the working power switch. When the working power supply fails or is under maintenance, the starting standby transformer (SPP) draws power from the high-voltage bus as a backup power source to ensure the continuity of auxiliary power. However, during periods when the SPP is out of service due to planned maintenance or a fault, the auxiliary power system effectively degrades to a single power supply. If the working power supply trips, the auxiliary power will be completely lost, severely impacting unit safety.

[0003] Energy storage systems are increasingly used in thermal power plants, primarily for ancillary services such as grid frequency regulation and peak shaving. Some existing technologies have already incorporated energy storage systems into thermal power plants as backup power sources. For example, Chinese patent application CN114825597A discloses a high-voltage direct-connected energy storage backup power system for thermal power plants. This system connects the energy storage power supply unit directly to the low-voltage side of the thermal power unit's standby transformer via an energy storage step-up transformer, allowing the energy storage to supply power to the plant's auxiliary loads when a grid failure causes the generator to shut down. However, this scheme still has significant shortcomings: First, the energy storage system only serves as a backup power source after an accident, and its switching depends on the generator shutdown signal, which is a passive response power supply. During normal operation, the energy storage device is not in an active voltage build-up standby state. Once the working power is interrupted, the energy storage system needs to go through a series of actions such as startup, voltage build-up, and closing before it can supply power, resulting in a switching delay of several seconds. Second, this scheme achieves power supply by connecting energy storage in parallel on the low-voltage side of the standby transformer. The energy storage needs to be stepped up by the step-up transformer before it can be connected to the 6kV bus, which increases the system complexity and power loss. Third, this scheme does not involve the coordinated control of the fast-switching device and the energy storage, and cannot achieve rapid switching between the working power source and the energy storage power source.

[0004] Furthermore, existing fast-start switching devices for thermal power plants are typically used for switching between the working power source and the standby transformer. Their switching logic is based on voltage amplitude and phase angle difference detection, with a switching time generally within 100 milliseconds. However, when the standby transformer exits standby mode, the existing fast-start switching device loses its standby power source target and cannot automatically switch to energy storage power. Existing patents such as CN202220931374.3 (A Black Start Switching System for Plant Auxiliary Power) address the switching problem between energy storage and gas turbine power generation, but primarily solve the switching between energy storage and gas turbine power generation during the gas turbine black start process. They do not limit the scenario to "during standby transformer maintenance" and do not highlight the active grid-connected strategy of VF mode. CN120341911A (A Method for Coupling Grid-Connected Energy Storage with Thermal Power Black Start) focuses on the coordinated frequency response and black start path optimization of grid-connected energy storage and thermal power units, aiming to improve black start recovery efficiency. It belongs to "post-accident recovery" rather than "pre-accident preventative protection." Meanwhile, existing technologies have not yet proposed a technical solution for using energy storage systems to pre-establish bus voltage and maintain hot standby in a grid-like manner, and for achieving uninterrupted switching between the working power supply and energy storage through fast switching devices. Summary of the Invention

[0005] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a device and method for utilizing the power supply and storage of thermal power plants. It has the advantages of fast power supply switching speed, simple system structure, and high power supply reliability. It solves the problems of large switching delays and inability to achieve uninterrupted power supply during the start-up and deactivation of existing energy storage backup power solutions and when the working power supply is interrupted.

[0006] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: This invention provides, in one aspect, a device for utilizing the power supply and storage capacity of a thermal power plant, comprising: The energy storage system is connected to the plant power bus via an energy storage converter PCS and an energy storage access switch; A quick-switching device is connected between the working power switch and the energy storage access switch; The controller is connected to the energy storage converter PCS and the fast-switching device, respectively. The controller is used to control the energy storage converter PCS to establish bus voltage in grid mode under specific conditions, and to obtain the opening and closing status of the working power switch. When the controller receives a trip signal and determines that the working power switch has tripped, the controller controls the fast switching device to switch to the energy storage system for power supply.

[0007] The grid configuration mode is a voltage-frequency (VF) control mode, and the plant power bus is a 6kV bus. The specific conditions include starting the standby transformer to exit the standby state. During the period when the standby transformer is started to exit the standby state, the controller controls the energy storage converter PCS to establish the bus voltage in the grid configuration mode and maintain the hot standby voltage building state.

[0008] The working power switch is located between the high-voltage plant transformer and the plant power bus, and the energy storage access switch is located between the energy storage converter PCS and the plant power bus; the controller obtains the opening and closing status signal of the working power switch through the auxiliary contacts of the working power switch.

[0009] The specific conditions also include periods of strong typhoons; the controller is also used to control the energy storage converter PCS to establish bus voltage in grid mode during periods of strong typhoons.

[0010] The controller controls the fast-switching device to switch to the energy storage system for power supply, including: the controller controls the fast-switching device to disconnect the working power switch and turn on the energy storage access switch; the time from disconnecting the working power switch to turning on the energy storage access switch is no more than 100 milliseconds.

[0011] The controller is also used to control the fast-switching device to switch to the energy storage system for power supply in response to an external manual start command.

[0012] The high-voltage plant service transformer, the start-up standby transformer, and the energy storage system form a three-level backup power supply system, with power supply priorities decreasing sequentially. The energy storage system serves as the third-level backup power source, acting as a backup power source for the plant service bus during the period when the start-up standby transformer is out of standby mode.

[0013] The energy storage system further includes an energy storage bus, a first PCS outgoing switch, a second PCS outgoing switch, and an energy storage outgoing switch; the energy storage converter PCS includes a first energy storage converter and a second energy storage converter, the first energy storage converter is connected to the energy storage bus via the first PCS outgoing switch, the second energy storage converter is connected to the energy storage bus via the second PCS outgoing switch, and the energy storage bus is connected to the energy storage access switch via the energy storage outgoing switch.

[0014] Another aspect of the present invention provides a method for distributing, storing, and protecting power from thermal power plants, and an apparatus applied to the above-mentioned aspect, comprising: Under specific conditions, the energy storage converter PCS is switched to grid-connected mode to establish bus voltage; Obtain the open / closed status of the power supply switch; When a trip signal is received and it is determined that the working power switch has tripped, the power supply is switched to the energy storage system via a fast-switching device.

[0015] The grid configuration mode is a voltage-frequency (VF) control mode, and the plant power bus is a 6kV bus. The specific conditions include starting the standby transformer to exit the standby state. During the period when the standby transformer is started to exit the standby state, the energy storage converter PCS is controlled to establish the bus voltage in the grid configuration mode and maintain a hot standby voltage build-up state. The switching to the energy storage system power supply through the fast switching device includes: disconnecting the working power switch and turning on the energy storage access switch, and the time from disconnecting the working power switch to turning on the energy storage access switch is no more than 100 milliseconds.

[0016] (III) Beneficial Effects Compared with the prior art, the present invention provides a device and method for utilizing the power supply and storage capacity of thermal power plants, which has the following beneficial effects: This invention utilizes a power storage converter (PCS) in a VF grid configuration to pre-establish bus voltage and maintain a hot standby voltage build-up state. Combined with a fast-switching device, it performs a first-out-then-on switching, achieving uninterrupted and rapid switching of plant power. Simultaneously, it forms a three-tiered backup power supply system: "high-voltage plant transformer—starting standby transformer—energy storage." During the period when the starting standby transformer is out of standby, energy storage serves as a backup power source, solving the technical problem of existing dual-power architectures having no backup power available during outages. This represents a shift from "post-accident recovery" to "pre-accident preventative protection." Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating the principle of power plant power distribution, storage, and protection provided by the present invention.

[0018] In the diagram: 1. High-voltage plant service transformer; 2. Working power switch; 3. Start-up standby transformer; 4. Plant service busbar; 5. Fast switching device; 6. First energy storage converter; 7. Second energy storage converter; 8. First PCS outgoing switch; 9. Second PCS outgoing switch; 10. Energy storage busbar; 11. Energy storage outgoing switch; 12. Energy storage access switch; 13. Controller. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0020] Please see Figure 1The electrical system structure of the thermal power plant used in this invention is as follows: The 220kV busbar includes Bus I and Bus II. The high-voltage side of the No. 1 main transformer is connected to the 220kV Bus I via switch 21A and to the 220kV Bus II via switch 21H. The low-voltage side of the No. 1 main transformer is connected to the outlet of Generator #1. Generator #1 is stepped up by the No. 1 main transformer and then connected to the 220kV busbar. The high-voltage side of the high-voltage plant service transformer 1 is connected to the electrical circuit between Generator #1 and the No. 1 main transformer via switch 62A. The low-voltage side is connected to the 6kV 1A section busbar via working power switch 2, serving as the normal operating power supply for the plant service. The high-voltage side of the start-up standby transformer 3 is connected to the 220kV busbar, and the low-voltage side is connected to the 6kV 1A section busbar via standby power switch, serving as the standby power supply for the plant service.

[0021] In one embodiment, the present invention provides a device for power supply protection in thermal power plants, comprising an energy storage system, a fast-switching device 5, and a controller 13. The energy storage system is connected to the plant auxiliary power bus 4 via an energy storage converter (PCS) and an energy storage access switch 12. The output of the energy storage converter (PCS) is connected to a 6kV 1A section bus via the energy storage access switch 12. The energy storage converter (PCS) converts the DC power output from the energy storage device into AC power, and its output voltage level matches the voltage of the plant auxiliary power bus 4. The energy storage access switch 12 controls the connection and disconnection between the energy storage system and the plant auxiliary power bus 4. The fast-switching device 5 is connected between the working power switch 2 and the energy storage access switch 12, and is used to perform plant auxiliary power switching operations. The controller 13 is connected to both the energy storage converter (PCS) and the fast-switching device 5, and is used to control the energy storage converter (PCS) to establish the bus voltage in grid mode under specific conditions, and to obtain the opening and closing status of the working power switch 2.

[0022] In one embodiment, the grid-connected mode refers to the energy storage converter PCS operating in voltage-frequency (VF) control mode, actively establishing and maintaining a stable voltage amplitude and frequency as an independent voltage source, independent of the external power grid. Unlike the grid-following mode, the grid-connected mode can autonomously establish and maintain the bus voltage when the power grid fails or the plant auxiliary power bus 4 loses voltage. The controller 13 controls the energy storage converter PCS to establish the bus voltage in grid-connected mode under specific conditions, including starting the standby transformer 3 to exit standby mode. During the period when the standby transformer 3 is started to exit standby mode, the controller 13 controls the energy storage converter PCS to establish a 6kV bus voltage in VF grid-connected mode and maintain a hot standby voltage build-up state. The hot standby voltage build-up state refers to the energy storage converter PCS operating in VF control mode, having established a voltage consistent with the rated voltage and frequency of the plant auxiliary power bus 4, with the energy storage access switch 12 in the open state, and the energy from the energy storage system being delivered to the upper port of the energy storage access switch 12 for standby but not fed into the plant auxiliary power bus 4, while the plant auxiliary power bus 4 is still powered by the working power source.

[0023] In one embodiment, the power supply switch 2 is located between the high-voltage station service transformer 1 and the station service bus 4, and the energy storage access switch 12 is located between the energy storage converter PCS and the station service bus 4. The controller 13 obtains the opening and closing status signal of the power supply switch 2 through its auxiliary contacts. The auxiliary contacts are mechanically linked to the main contacts of the power supply switch 2. When the main contacts are closed, the auxiliary contacts output a closing signal; when the main contacts are open, the auxiliary contacts output a opening signal. The controller 13 monitors whether the power supply switch 2 has tripped in real time by reading this signal.

[0024] In one embodiment, the specific conditions also include periods of severe typhoons. During periods of severe typhoons, the controller 13 controls the energy storage converter PCS to establish bus voltage in VF grid-connected mode. During extreme weather periods such as severe typhoons, the external power grid has a high risk of failure. The controller 13 controls the energy storage converter PCS in advance to establish bus voltage in grid-connected mode and maintains a hot standby voltage-building state, while the energy storage access switch 12 is in the open state.

[0025] In one embodiment, when the controller 13 receives a trip signal and determines that the working power switch 2 has tripped, the controller 13 controls the fast-switching device 5 to switch to the energy storage system for power supply. Specifically, the controller 13 controls the fast-switching device 5 to disconnect the working power switch 2 and connect the energy storage access switch 12. The time from disconnecting the working power switch 2 to connecting the energy storage access switch 12 is no more than 100 milliseconds. The controller 13 first confirms that the working power switch 2 has been disconnected, and then connects the energy storage access switch 12. This "disconnect first, connect later" series switching logic ensures that the working power supply and the energy storage power supply will not operate in parallel, avoiding damage to the equipment caused by closed-loop operation. The basis for the switching time of no more than 100 milliseconds comes from the national standard "Design Code for Small Thermal Power Plants" (GB50049-2011), which defines "the switching time of high-voltage power supply accidents in power plants is no more than 100ms" as fast switching in Article 2.0.10. When the switching time is controlled within 100ms, the phase difference between the residual voltage of the plant bus and the voltage of the energy storage power supply does not exceed 30°, which can avoid the generation of large inrush current when closing the circuit and ensure the safe operation of rotating loads such as motors.

[0026] In one embodiment, the controller 13 is also configured to control the fast-switching device 5 to switch to power supply from the energy storage system in response to an external manual start command. When the unit needs to be shut down during the period when the standby transformer 3 is out of standby, the operator issues a manual start command. In response to the command, the controller 13 controls the fast-switching device 5 to disconnect the working power switch 2. After confirming that it has been disconnected, the controller 13 turns on the energy storage access switch 12 to switch to power supply from the energy storage system.

[0027] In one embodiment, the high-voltage plant service transformer 1, the start-up standby transformer 3, and the energy storage system form a three-level backup power supply system, with power supply priorities decreasing sequentially: the first level is the high-voltage plant service transformer 1, the second level is the start-up standby transformer 3, and the third level is the energy storage system. The energy storage system, as the third-level backup power source, serves as a backup power source for the plant service bus 4 while the start-up standby transformer 3 is out of standby mode. When the start-up standby transformer 3 resumes normal operation, the plant service system reverts to a dual-power supply architecture, and the energy storage system exits the third-level standby state.

[0028] In one embodiment, the energy storage system further includes an energy storage bus 10, a first PCS output switch 8, a second PCS output switch 9, and an energy storage output switch 11. The energy storage converter PCS includes a first energy storage converter 6 and a second energy storage converter 7, which are redundantly configured. The output of the first energy storage converter 6 is connected to the energy storage bus 10 via the first PCS output switch 8, the output of the second energy storage converter 7 is connected to the energy storage bus 10 via the second PCS output switch 9, and the energy storage bus 10 is connected to the energy storage access switch 12 via the energy storage output switch 11. In hot standby power-up mode, the energy storage outgoing switch 11 is closed, and the energy storage incoming switch 12 is open. The electrical energy output from the energy storage converter PCS is sent to the energy storage bus 10 via the first PCS outgoing switch 8 or the second PCS outgoing switch 9, and then to the upper port of the energy storage incoming switch 12 via the energy storage outgoing switch 11 for standby, but is not fed into the plant auxiliary power bus 4. When the energy storage incoming switch 12 is turned on, the stored electrical energy is instantly fed into the plant auxiliary power bus 4. Both energy storage converters are in hot standby mode, and the load is evenly distributed between them during normal operation. If one fails, the other can take over the entire load.

[0029] In one embodiment, the generator-transformer protection device is existing equipment in the thermal power plant, used to detect the operating status of the generator and main transformer, and to issue a trip signal when a fault occurs. The controller 13 is connected to the generator-transformer protection device to receive the trip signal.

[0030] Another aspect of the present invention provides a method for utilizing the power supply and storage of thermal power plants, applied to the aforementioned device, comprising the following steps.

[0031] Step 1: Under specific conditions, switch the energy storage converter PCS to VF grid-connected mode to establish bus voltage. Specific conditions include starting standby transformer 3 to exit standby mode. During the period when standby transformer 3 is starting to exit standby mode, control the energy storage converter PCS to establish bus voltage in VF grid-connected mode and maintain a hot standby voltage build-up state. In the hot standby voltage build-up state, the energy storage access switch 12 is in the open state; the energy storage system has established voltage but it is not fed into the bus.

[0032] Step 2: Obtain the open / close status of the power switch 2. The controller 13 continuously monitors the open / close status signal of the power switch 2 through its auxiliary contacts.

[0033] Step 3: When the controller 13 receives a trip signal and determines that the working power switch 2 has tripped, it switches to power supply from the energy storage system via the fast-switching device 5. Switching to power supply from the energy storage system includes: disconnecting the working power switch 2 and turning on the energy storage access switch 12. The time from disconnecting the working power switch 2 to turning on the energy storage access switch 12 shall not exceed 100 milliseconds.

[0034] The working process of the device and method of the present invention will be further explained below with reference to specific application scenarios.

[0035] In one application scenario, hot standby voltage build-up occurs during the period when the standby transformer 3 is taken out of standby. When the standby transformer 3 is taken out of standby due to maintenance or failure, the backup power supply of the plant power system is lost, and the plant power system degrades to single-source power supply. During the period when the standby transformer 3 is taken out of standby, the controller 13 controls the energy storage converter PCS to switch to VF grid mode, actively establishes the 6kV bus voltage, and maintains the hot standby voltage build-up state. The 6kV voltage output by the energy storage converter PCS is sent to the energy storage bus 10 via the first PCS outgoing switch 8 or the second PCS outgoing switch 9, and then sent to the upper port of the energy storage access switch 12 for standby via the energy storage outgoing switch 11. At this time, the energy storage access switch 12 is in the open state, and power is not fed into the 6kV 1A section bus. The bus is still powered by the high-voltage plant power transformer 1 via the working power switch 2.

[0036] In another application scenario, automatic fault switching occurs. During the period when the standby transformer 3 is being activated and deactivated, if the generator set protection device detects a generator set fault, it sends a trip signal. One path of this trip signal drives the trip coil of the working power switch 2, causing it to trip; the other path is sent to the controller 13. Upon receiving the trip signal, the controller 13 determines whether the working power switch 2 has tripped via its auxiliary contacts. Once the controller 13 confirms that the working power switch 2 has tripped, it controls the fast-switching device 5 to disconnect the working power switch 2 and activate the energy storage access switch 12. Since the upper port of the energy storage access switch 12 already has energy storage voltage ready, the power is instantly fed into the bus after the switch closes, with a switching time of no more than 100 milliseconds, achieving uninterrupted power supply.

[0037] In another application scenario, manual switching occurs. During the period when the standby transformer 3 is being deactivated from standby, if the unit needs to be shut down normally, the operator issues a manual start command. Controller 13 responds to this command by controlling the fast-switching device 5 to disconnect the working power switch 2. After confirming that it is disconnected, it connects the energy storage access switch 12, switching to power supply from the energy storage system.

[0038] In another application scenario, during a severe typhoon, controller 13 controls the energy storage converter PCS to switch to VF grid-connected mode, establishing a 6kV bus voltage and maintaining a hot standby voltage build-up state. If an external grid fault causes the working power switch 2 to trip, controller 13 controls the fast-switching device 5 to switch power to the energy storage system according to the aforementioned fault switching logic. After the typhoon, the external grid stabilizes, and operators manually switch the plant auxiliary power back to the working power, exiting the VF control mode of the energy storage converter PCS.

[0039] Furthermore, the specific operating process of the three-level backup power supply is as follows: During normal operation, the high-voltage plant service transformer 1 supplies power to the plant service bus 4 via the working power switch 2. When the high-voltage plant service transformer 1 fails or is under maintenance, the starting standby transformer 3 supplies power to the plant service bus 4 via the backup power switch. During the period when the starting standby transformer 3 is out of standby mode, the energy storage system, as the third-level backup power source, supplies power to the plant service bus 4 via the energy storage access switch 12 when the working power supply of the high-voltage plant service transformer 1 is interrupted. When the starting standby transformer 3 resumes standby, the operators manually exit the VF control mode of the energy storage converter PCS, and the plant service system returns to a dual-power supply architecture.

[0040] In summary, this invention actively establishes the bus voltage and maintains a hot standby voltage-building state through the energy storage converter PCS in VF grid mode. Combined with the fast-switching device 5, it performs a first-break-then-connect switching when the working power supply trips, with a switching time of no more than 100 milliseconds, achieving uninterrupted power supply to the plant. Simultaneously, the energy storage converter PCS directly outputs 6kV voltage and connects to the plant power bus 4 via the energy storage access switch 12, eliminating the need for a step-up transformer and simplifying the system structure. This forms a three-level backup power supply system: "high-voltage plant power transformer 1—starting standby transformer 3—energy storage." During the period when the starting standby transformer 3 is de-emerged, the energy storage serves as a backup power source, effectively ensuring the reliability of the power supply to the thermal power plant.

[0041] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A device for utilizing the power supply, storage, and protection of thermal power plants, characterized in that, include: The energy storage system is connected to the plant power bus via an energy storage converter PCS and an energy storage access switch; A quick-switching device is connected between the working power switch and the energy storage access switch; The controller is connected to the energy storage converter PCS and the fast-switching device, respectively. The controller is used to control the energy storage converter PCS to establish bus voltage in grid mode under specific conditions, and to obtain the opening and closing status of the working power switch. When the controller receives a trip signal and determines that the working power switch has tripped, the controller controls the fast switching device to switch to the energy storage system for power supply.

2. The apparatus according to claim 1, characterized in that, The grid configuration mode is a voltage-frequency (VF) control mode, and the plant power bus is a 6kV bus. The specific conditions include starting the standby transformer to exit the standby state. During the period when the standby transformer is started to exit the standby state, the controller controls the energy storage converter PCS to establish the bus voltage in the grid configuration mode and maintain the hot standby voltage building state.

3. The apparatus according to claim 1, characterized in that, The working power switch is located between the high-voltage plant transformer and the plant power bus, and the energy storage access switch is located between the energy storage converter PCS and the plant power bus; the controller obtains the opening and closing status signal of the working power switch through the auxiliary contacts of the working power switch.

4. The apparatus according to claim 1, characterized in that, The specific conditions also include periods of strong typhoons; the controller is also used to control the energy storage converter PCS to establish bus voltage in grid mode during periods of strong typhoons.

5. The apparatus according to claim 1, characterized in that, The controller controls the fast-switching device to switch to the energy storage system for power supply, including: the controller controls the fast-switching device to disconnect the working power switch and turn on the energy storage access switch; the time from disconnecting the working power switch to turning on the energy storage access switch is no more than 100 milliseconds.

6. The apparatus according to claim 1, characterized in that, The controller is also used to control the fast-switching device to switch to the energy storage system for power supply in response to an external manual start command.

7. The apparatus according to claim 1, characterized in that, The high-voltage plant service transformer, the start-up standby transformer, and the energy storage system form a three-level backup power supply system, with power supply priority decreasing sequentially. The energy storage system serves as the third-level backup power source, acting as a backup power source for the plant service bus during the period when the start-up standby transformer is out of standby mode.

8. The apparatus according to claim 1, characterized in that, The energy storage system further includes an energy storage bus, a first PCS outgoing switch, a second PCS outgoing switch, and an energy storage outgoing switch; the energy storage converter PCS includes a first energy storage converter and a second energy storage converter, the first energy storage converter is connected to the energy storage bus via the first PCS outgoing switch, the second energy storage converter is connected to the energy storage bus via the second PCS outgoing switch, and the energy storage bus is connected to the energy storage access switch via the energy storage outgoing switch.

9. A method for utilizing the power supply and storage capacity of a thermal power plant, applied to the apparatus described in any one of claims 1 to 8, characterized in that, include: Under specific conditions, the energy storage converter PCS is switched to grid-connected mode to establish bus voltage; Obtain the open / closed status of the power supply switch; When a trip signal is received and it is determined that the working power switch has tripped, the power supply is switched to the energy storage system via a fast-switching device.

10. The method according to claim 9, characterized in that, The grid configuration mode is a voltage-frequency (VF) control mode, and the plant power bus is a 6kV bus. The specific conditions include starting the standby transformer to exit the standby state. During the period when the standby transformer is started to exit the standby state, the energy storage converter PCS is controlled to establish the bus voltage in the grid configuration mode and maintain a hot standby voltage build-up state. The step of switching to the energy storage system via the fast-switching device includes: disconnecting the working power switch and turning on the energy storage access switch, wherein the time from disconnecting the working power switch to turning on the energy storage access switch is no more than 100 milliseconds.

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