In-plant electric power system of thermal power plant

Abstract

The utility model belongs to the technical field of thermal power plants, and particularly relates to an in-plant electric power system of a thermal power plant, which comprises a high-voltage plant transformation unit, a medium-voltage self-use loop, a connection bus unit, a medium-voltage common loop and a common transformer, the high-voltage side of the high-voltage plant transformation unit is used for being connected with a thermal generator set, the medium-voltage self-use loop is connected with the low-voltage side of the high-voltage plant transformation unit, and the medium-voltage self-use loop is used for supplying power to a self-power system of a thermal power plant; the high-voltage side of the common transformer is used for being connected with an external high-voltage power supply, the medium-voltage common loop is connected with the low-voltage side of the common transformer, and the medium-voltage common loop is used for supplying power to a common power system of the thermal power plant; the connection bus unit is connected between the medium-voltage self-use loop and the medium-voltage common loop, the connection bus unit is provided with a circuit breaker unit, and the circuit breaker unit is used for controlling connection and disconnection between the medium-voltage self-use loop and the medium-voltage common loop.

Description

Technical Field

[0001] This utility model belongs to the technical field of thermal power plants, specifically relating to an internal power system for a thermal power plant. Background Technology

[0002] During startup, operation, shutdown, and maintenance, thermal power plants employ a large number of electrically driven mechanical devices to ensure the normal operation of major equipment (such as boilers, steam turbines, and generators) and coal conveying, ash removal, dust removal, and water treatment systems. These electric motors, along with all the plant's operating, testing, maintenance, and lighting equipment, constitute the plant's auxiliary power load.

[0003] Plant power load is divided into unit power load (also known as self-use power load) and common power load. Unit power load refers to the auxiliary power load dedicated to each unit, such as the motors of coal mills, coal feeders, induced draft fans, forced draft fans, primary air fans, circulating water pumps, condensate pumps, etc. These loads serve a single unit. Common power load refers to the auxiliary power loads shared by the entire plant, such as those for coal conveying, ash removal, water treatment, testing, maintenance, and lighting systems. These loads are shared by the entire plant and serve multiple units.

[0004] Existing medium-voltage power supply schemes for thermal power plants typically connect thermal generator units directly to the plant auxiliary power system as the main power source for the auxiliary power system. In order to ensure the starting power and common power supply when the thermal generator units are shut down, a backup power line is usually connected to the auxiliary power system as a backup power source for the thermal power plant's auxiliary power system, and also serves as the starting power source for the thermal generator units. However, this configuration, where both the main and backup power supplies directly power the entire plant's auxiliary power load, typically uses the main power supply during normal operation of the thermal power generating unit, leaving the backup power supply in a hot standby state (i.e., no-load operation). This leads to a lack of proper allocation between the main and backup power supplies, resulting in an excessively high transformer load rate (the ratio of actual load to rated load) for the main power supply (usually exceeding 80%), while the transformer load rate for the backup power supply is too low (usually below 1%). (Theoretically, transformer efficiency reaches its peak when iron loss equals copper loss, i.e., no-load loss equals load loss. The corresponding load rate at this point is generally around 40%-60%). This ultimately results in low efficiency for both the main and backup power supply transformers. Utility Model Content

[0005] To address the shortcomings of the existing technology, this utility model provides an in-plant power system for thermal power plants. This system solves the problem that, during normal operation of thermal power generating units, the lack of proper allocation between the main power supply and backup power supply leads to excessively high transformer load rates for the main power supply and excessively low transformer load rates for the backup power supply, resulting in low efficiency for both the main and backup power supply transformers.

[0006] To achieve the above objectives, the technical solution of this utility model is as follows:

[0007] An internal power system for a thermal power plant includes a high-voltage plant auxiliary transformer unit, a medium-voltage self-use circuit, a connecting busbar unit, a medium-voltage common circuit, and a common transformer;

[0008] The high-voltage side of the high-voltage plant auxiliary transformer unit is used to connect to the thermal power generating unit, and the medium-voltage self-use circuit is connected to the low-voltage side of the high-voltage plant auxiliary transformer unit. The medium-voltage self-use circuit is used to supply power to the self-use power system of the thermal power plant.

[0009] The high-voltage side of the public transformer is used to connect to an external high-voltage power source, and the medium-voltage public circuit is connected to the low-voltage side of the public transformer. The medium-voltage public circuit is used to supply power to the public power system of the thermal power plant.

[0010] The connecting bus unit is connected between the medium-voltage self-use circuit and the medium-voltage common circuit. The connecting bus unit is equipped with a circuit breaker unit, which is used to control the connection and disconnection between the medium-voltage self-use circuit and the medium-voltage common circuit.

[0011] By setting up the medium-voltage self-use circuit, the connecting bus unit, and the medium-voltage common circuit, the high-voltage plant auxiliary transformer unit serves as the main power source for the thermal power plant's self-use power system, and the common transformer serves as the main power source for the thermal power plant's common power system. The connecting bus unit allows both to serve as backup power sources for each other. This achieves the function of using the common transformer as a backup power source for the thermal power plant's auxiliary power system (including the medium-voltage self-use circuit and the medium-voltage common circuit), and also as a starting power source for the thermal power generating units. Furthermore, it enables the high-voltage plant auxiliary transformer unit to serve as the main power source for the thermal power plant's auxiliary power system (including the medium-voltage self-use circuit and the medium-voltage common circuit) (i.e., the functions achievable by existing thermal power plant medium-voltage system power supply schemes). Furthermore, it enables the high-voltage plant service transformer unit to supply power to the medium-voltage self-use circuit independently, and the common transformer to supply power to the medium-voltage common circuit independently, during the normal operation of the thermal power generating unit. This allows for the rational allocation of the main power source (i.e., the thermal power generating unit and the high-voltage plant service transformer unit) and the backup power source (i.e., the external high-voltage power source and the common transformer). During the normal operation of the thermal power generating unit, it can effectively reduce the load rate of the main power source transformer (i.e., the high-voltage plant service transformer unit) and prevent the backup power source from being in a hot standby state, thereby increasing the load rate of the backup power source transformer (i.e., the common transformer) and achieving the technical effect of improving the efficiency of the main power source and the backup power source transformer (i.e., the high-voltage plant service transformer unit and the common transformer).

[0012] Meanwhile, using the public transformer to supply power specifically to the public power system of the thermal power plant can avoid the need to switch the power supply to the public power system when the thermal power generating units are shut down, making operation more convenient.

[0013] Furthermore, the high-voltage plant auxiliary transformer unit includes multiple high-voltage plant auxiliary transformers;

[0014] The medium-voltage self-use circuit includes multiple medium-voltage self-use busbar sections; each of the high-voltage plant service transformers is connected to multiple medium-voltage self-use busbar sections on its low-voltage side, and each of the medium-voltage self-use busbar sections is connected to the low-voltage side of the high-voltage plant service transformer through a first circuit breaker.

[0015] Furthermore, the high-voltage plant service transformer unit includes two high-voltage plant service transformers.

[0016] Furthermore, the number of medium-voltage self-use busbar sections connected to the low-voltage side of the two high-voltage plant service transformers is the same, and they are set up in a one-to-one correspondence.

[0017] The connecting bus unit includes a plurality of first connecting buses;

[0018] Each of the medium-voltage self-use busbar sections on any of the high-voltage plant service transformers is connected to a first connecting busbar between a corresponding medium-voltage self-use busbar section on another high-voltage plant service transformer; each of the first connecting busbars is connected to the medium-voltage common circuit.

[0019] The circuit breaker unit includes multiple circuit breaker components, and one of the circuit breaker components is provided on each of the first connecting busbars.

[0020] Furthermore, the circuit breaker assembly includes two second circuit breakers, one end of the first connecting busbar is connected to one of the medium-voltage self-use busbar sections through one of the second circuit breakers, and the other end of the first connecting busbar is connected to the corresponding medium-voltage self-use busbar section through the other second circuit breaker.

[0021] By connecting one end of the first connecting busbar to one of the medium-voltage self-use busbar sections through one of the second circuit breakers, and connecting the other end of the first connecting busbar to the corresponding medium-voltage self-use busbar section through another second circuit breaker, the on / off control between the medium-voltage common circuit and any of the medium-voltage self-use busbar sections can be realized. This increases the precision of load allocation for the main power supply (i.e., the thermal power generating unit and the high-voltage plant service transformer unit) and the backup power supply (i.e., the external high-voltage power supply and the common transformer), which is beneficial to ensuring that the common transformer and each of the high-voltage plant service transformers operate at the optimal load rate, further improving the efficiency of the common transformer and each of the high-voltage plant service transformers.

[0022] Furthermore, the connecting bus unit also includes a plurality of second connecting buses, and each of the first connecting buses is connected to the medium-voltage common circuit through a second connecting bus.

[0023] Furthermore, each of the high-voltage plant service transformers is connected to two medium-voltage self-use busbar sections on its low-voltage side.

[0024] Furthermore, the medium-voltage common circuit includes multiple medium-voltage common busbar sections, and each of the medium-voltage self-use busbar sections is connected to the low-voltage side of the common transformer through a third circuit breaker.

[0025] Furthermore, the medium-voltage common circuit includes two medium-voltage common bus sections.

[0026] Furthermore, the connecting bus unit includes two first connecting buses;

[0027] The circuit breaker unit includes two circuit breaker assemblies, and one circuit breaker assembly is provided on each of the first connecting busbars;

[0028] One of the first connecting busbars is used to connect one of the medium-voltage common busbar segments to several of the medium-voltage self-use busbar segments; the other first connecting busbar is used to connect another of the medium-voltage common busbar segments to the remaining medium-voltage self-use busbar segments;

[0029] The circuit breaker assembly is used to control the connection and disconnection between the medium-voltage common busbar section and each of the medium-voltage self-use busbar sections.

[0030] The power system for thermal power plants provided by this utility model has at least the following technical effects or advantages:

[0031] 1. By setting up the medium-voltage self-use circuit, the connecting bus unit, and the medium-voltage common circuit, the high-voltage plant auxiliary transformer unit is used as the main power source for the self-use power system of the thermal power plant, and the common transformer is used as the main power source for the common power system of the thermal power plant. The connecting bus unit allows both to serve as backup power sources for each other. This achieves the function of using the common transformer as a backup power source for the plant auxiliary power system (including the medium-voltage self-use circuit and the medium-voltage common circuit) of the thermal power plant, and also as a starting power source for the thermal power generating units. Furthermore, the high-voltage plant auxiliary transformer unit can also serve as the main power source for the plant auxiliary power system (including the medium-voltage self-use circuit and the medium-voltage common circuit) of the thermal power plant (i.e., the function that existing medium-voltage power supply schemes for thermal power plants can achieve). Furthermore, when the thermal power generating unit is in normal operation, the high-voltage plant service transformer unit can independently supply power to the medium-voltage self-use circuit, and the common transformer can independently supply power to the medium-voltage common circuit. This enables reasonable allocation of the main power source (i.e., the thermal power generating unit and the high-voltage plant service transformer unit) and the backup power source (i.e., the external high-voltage power source and the common transformer). When the thermal power generating unit is in normal operation, it can effectively reduce the load rate of the main power source transformer (i.e., the high-voltage plant service transformer unit) and prevent the backup power source from being in a hot standby state, thereby increasing the load rate of the backup power source transformer (i.e., the common transformer) and achieving the technical effect of improving the efficiency of the main power source and the backup power source transformer (i.e., the high-voltage plant service transformer unit and the common transformer).

[0032] 2. Utilizing the aforementioned public transformer to supply power specifically to the public power system of the thermal power plant can also avoid the need to switch the power supply to the public power system when the thermal power generating units are shut down, making operation more convenient.

[0033] 3. By connecting one end of the first connecting busbar to one of the medium-voltage self-use busbar sections through one of the circuit breakers, and connecting the other end of the first connecting busbar to the corresponding medium-voltage self-use busbar section through another circuit breaker, the on / off control between the medium-voltage common circuit and any of the medium-voltage self-use busbar sections can be realized. This increases the precision of load allocation for the main power supply (i.e., the thermal power generating unit and the high-voltage plant service transformer unit) and the backup power supply (i.e., the external high-voltage power supply and the common transformer), which is beneficial to ensuring that the common transformer and each of the high-voltage plant service transformers operate at the optimal load rate, further improving the efficiency of the common transformer and each of the high-voltage plant service transformers. Attached Figure Description

[0034] To more clearly illustrate the technical solution of this utility model, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a topology diagram of the power system within a thermal power plant in the embodiment.

[0036] 1—High-voltage plant service transformer, 2—Public transformer, 3—Medium-voltage self-use busbar section, 4—First connecting busbar, 5—Second circuit breaker, 6—Second connecting busbar, 7—Medium-voltage public busbar section. Detailed Implementation

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0038] like Figure 1 As shown, this embodiment provides an in-plant power system for a thermal power plant, including a high-voltage plant auxiliary transformer unit, a medium-voltage self-use circuit, a connecting busbar unit, a medium-voltage common circuit, and a common transformer 2;

[0039] The high-voltage side of the high-voltage plant auxiliary transformer unit is used to connect to the thermal power generating unit, and the medium-voltage self-use circuit is connected to the low-voltage side of the high-voltage plant auxiliary transformer unit. The medium-voltage self-use circuit is used to supply power to the self-use power system of the thermal power plant.

[0040] The high-voltage side of the public transformer 2 is used to connect to an external high-voltage power source, and the medium-voltage public circuit is connected to the low-voltage side of the public transformer 2. The medium-voltage public circuit is used to supply power to the public power system of the thermal power plant.

[0041] The connecting bus unit is connected between the medium-voltage self-use circuit and the medium-voltage common circuit. The connecting bus unit is equipped with a circuit breaker unit, which is used to control the connection and disconnection between the medium-voltage self-use circuit and the medium-voltage common circuit.

[0042] By setting up a medium-voltage self-use circuit, connecting busbar units, and a medium-voltage common circuit, the high-voltage plant auxiliary transformer unit is used as the main power source for the thermal power plant's self-use power system, and the common transformer 2 is used as the main power source for the thermal power plant's common power system. The connecting busbar unit allows both to serve as backup power sources for each other. This achieves the function of using the common transformer 2 as a backup power source for the thermal power plant's auxiliary power system (including the medium-voltage self-use circuit and the medium-voltage common circuit), and also as a starting power source for the thermal power generating units. Furthermore, it enables the high-voltage plant auxiliary transformer unit to serve as the main power source for the thermal power plant's auxiliary power system (including the medium-voltage self-use circuit and the medium-voltage common circuit) (i.e., the functions that existing thermal power plant medium-voltage system power supply schemes can achieve). This system enables the high-voltage auxiliary transformer unit to supply power independently to the medium-voltage self-use circuit, and the common transformer 2 to supply power independently to the medium-voltage common circuit, during the normal operation of the thermal power generating unit. This allows for the rational allocation of the main power source (i.e., the thermal power generating unit and the high-voltage auxiliary transformer unit) and the backup power source (i.e., the external high-voltage power source and the common transformer 2). During the normal operation of the thermal power generating unit, it can effectively reduce the load rate of the main power source transformer (i.e., the high-voltage auxiliary transformer unit) and prevent the backup power source from being in a hot standby state, thereby increasing the load rate of the backup power source transformer (i.e., the common transformer 2). This achieves the technical effect of improving the efficiency of both the main power source and the backup power source transformers (i.e., the high-voltage auxiliary transformer unit and the common transformer 2).

[0043] At the same time, by using public transformer 2 to supply power to the public power system of the thermal power plant, the operation of switching the power supply of the public power system can be avoided when the thermal power generating units are shut down, making the operation more convenient.

[0044] In one embodiment, such as Figure 1 As shown, the high-voltage plant service transformer unit includes multiple high-voltage plant service transformers 1;

[0045] The medium-voltage self-use circuit includes multiple medium-voltage self-use busbar sections 3; each high-voltage plant service transformer 1 has multiple medium-voltage self-use busbar sections 3 connected to its low-voltage side, and each medium-voltage self-use busbar section 3 is connected to the low-voltage side of the high-voltage plant service transformer 1 through a first circuit breaker.

[0046] Specifically, in this embodiment, such as Figure 1 As shown, the high-voltage plant service transformer unit includes two high-voltage plant service transformers 1.

[0047] In one embodiment, such as Figure 1As shown, the number of medium-voltage self-use busbar sections 3 connected to the low-voltage side of the two high-voltage plant service transformers 1 is the same, and they are set up one-to-one.

[0048] The connecting bus unit includes multiple first connecting buses 4;

[0049] A first connecting busbar 4 is connected between any medium-voltage self-use busbar segment 3 on any high-voltage plant service transformer 1 and the corresponding medium-voltage self-use busbar segment 3 on another high-voltage plant service transformer 1; each first connecting busbar 4 is connected to the medium-voltage common circuit.

[0050] The circuit breaker unit includes multiple circuit breaker assemblies, with one circuit breaker assembly installed on each first connecting bus 4.

[0051] Specifically, in this embodiment, such as Figure 1 As shown, the circuit breaker assembly includes two second circuit breakers 5. One end of the first connecting busbar 4 is connected to one of the medium-voltage self-use busbar sections 3 through one of the second circuit breakers 5, and the other end of the first connecting busbar 4 is connected to the corresponding medium-voltage self-use busbar section 3 through the other second circuit breaker 5.

[0052] By connecting one end of the first connecting busbar 4 to one of the medium-voltage self-use busbar sections 3 through one of the second circuit breakers 5, and connecting the other end of the first connecting busbar 4 to the corresponding medium-voltage self-use busbar section 3 through another second circuit breaker 5, the on / off control between the medium-voltage public circuit and any medium-voltage self-use busbar section 3 can be realized. This increases the precision of load allocation for the main power supply (i.e., thermal power generating units and high-voltage plant service transformer units) and the backup power supply (i.e., external high-voltage power supply and public transformer 2). It is beneficial to ensure that the public transformer 2 and each high-voltage plant service transformer 1 operate at the optimal load rate, further improving the efficiency of the public transformer 2 and each high-voltage plant service transformer 1.

[0053] Specifically, in this embodiment, such as Figure 1 As shown, the connecting bus unit also includes multiple second connecting buses 6, and each first connecting bus 4 is connected to the medium-voltage common circuit through a second connecting bus 6.

[0054] Specifically, in this embodiment, such as Figure 1 As shown, each high-voltage plant service transformer 1 is connected to two medium-voltage self-use busbar sections 3 on its low-voltage side.

[0055] In one embodiment, such as Figure 1 As shown, the medium-voltage public circuit includes multiple medium-voltage public bus sections 7, and each medium-voltage self-use bus section 3 is connected to the low-voltage side of the public transformer 2 through a third circuit breaker.

[0056] Specifically, in this embodiment, such as Figure 1As shown, the medium-voltage common circuit includes two medium-voltage common busbar segments 7.

[0057] To facilitate understanding of the connection method between the medium-voltage public busbar section 7 and the medium-voltage self-use busbar section 3 in this utility model, the configuration method of the connecting busbar unit is described again in another way: the connecting busbar unit includes two first connecting busbars 4;

[0058] The circuit breaker unit includes two circuit breaker assemblies, with one circuit breaker assembly installed on each of the first connecting busbars 4;

[0059] One of the first connecting busbars 4 is used to connect one of the medium-voltage common busbar sections 7 and several medium-voltage self-use busbar sections 3; the other first connecting busbar 4 is used to connect another medium-voltage common busbar section 7 and the remaining medium-voltage self-use busbar sections 3;

[0060] The circuit breaker assembly is used to control the connection and disconnection between the medium-voltage common busbar section 7 and each medium-voltage self-use busbar section 3.

[0061] Specifically, in this embodiment, such as Figure 1 As shown, one of the first connecting busbars 4 is used to connect one of the medium-voltage public busbar segments 7 and two of the medium-voltage private busbar segments 3; the other first connecting busbar 4 is used to connect another medium-voltage public busbar segment 7 and two other medium-voltage private busbar segments 3.

[0062] Preferably, in this embodiment, such as Figure 1 As shown, one end of the first connecting busbar 4 is connected to one of the medium-voltage self-use busbar sections 3, and the other end of the first connecting busbar 4 is connected to the corresponding medium-voltage self-use busbar section 3.

[0063] The power system for thermal power plants provided by this utility model has at least the following technical effects or advantages:

[0064] 1. By setting up a medium-voltage self-use circuit, connecting busbar units, and a medium-voltage common circuit, the high-voltage plant auxiliary transformer unit is used as the main power source for the thermal power plant's self-use power system, and the common transformer 2 is used as the main power source for the thermal power plant's common power system. The connecting busbar unit allows both to serve as backup power sources for each other. This achieves the function of using the common transformer 2 as a backup power source for the thermal power plant's auxiliary power system (including the medium-voltage self-use circuit and the medium-voltage common circuit), and also as a starting power source for the thermal power generating units. Furthermore, it enables the high-voltage plant auxiliary transformer unit to serve as the main power source for the thermal power plant's auxiliary power system (including the medium-voltage self-use circuit and the medium-voltage common circuit) (i.e., the functions achievable by existing thermal power plant medium-voltage system power supply schemes). It enables the high-voltage plant auxiliary transformer unit to supply power to the medium-voltage self-use circuit independently, and the common transformer 2 to supply power to the medium-voltage common circuit independently, during the normal operation of the thermal power generating unit. This allows for the rational allocation of the main power source (i.e., the thermal power generating unit and the high-voltage plant auxiliary transformer unit) and the backup power source (i.e., the external high-voltage power source and the common transformer 2). During the normal operation of the thermal power generating unit, it can effectively reduce the load rate of the main power source transformer (i.e., the high-voltage plant auxiliary transformer unit) and prevent the backup power source from being in a hot standby state, thereby increasing the load rate of the backup power source transformer (i.e., the common transformer 2) and achieving the technical effect of improving the efficiency of the main power source and the backup power source transformer (i.e., the high-voltage plant auxiliary transformer unit and the common transformer 2).

[0065] 2. Using public transformer 2 to supply power to the public power system of the thermal power plant can also avoid the need to switch the power supply of the public power system when the thermal power generating unit is shut down, making the operation more convenient.

[0066] 3. By connecting one end of the first connecting busbar 4 to one of the medium-voltage self-use busbar sections 3 through one of the second circuit breakers 5, and connecting the other end of the first connecting busbar 4 to the corresponding medium-voltage self-use busbar section 3 through another second circuit breaker 5, the on / off control between the medium-voltage public circuit and any medium-voltage self-use busbar section 3 can be realized. This increases the precision of load distribution for the main power supply (i.e., thermal power generating units and high-voltage plant service transformer units) and the backup power supply (i.e., external high-voltage power supply and public transformer 2). It is beneficial to ensure that the public transformer 2 and each high-voltage plant service transformer 1 operate at the optimal load rate, and further improve the efficiency of the public transformer 2 and each high-voltage plant service transformer 1.

[0067] The above are merely specific application examples of this utility model and do not constitute any limitation on the scope of protection of this utility model. All technical solutions formed by equivalent transformation or equivalent substitution fall within the scope of protection of this utility model.

Claims

1. An intra-plant power system of a thermal power plant, characterized by: The high-voltage plant transformer unit, the medium-voltage self-use circuit, the connecting bus unit, the medium-voltage public circuit and the public transformer are connected in series. The high-voltage side of the high-voltage plant transformer unit is used for being connected with a thermal power generator unit, the low-voltage side of the high-voltage plant transformer unit is connected with the medium-voltage self-use circuit, and the medium-voltage self-use circuit is used for supplying power to a self-use electric system of the thermal power plant. The high-voltage side of the public transformer is used for being connected with an external high-voltage power supply, the low-voltage side of the public transformer is connected with the medium-voltage public circuit, and the medium-voltage public circuit is used for supplying power to a public electric system of the thermal power plant. The connecting bus unit is connected between the medium-voltage self-use circuit and the medium-voltage public circuit, and the connecting bus unit is provided with a circuit breaker unit used for controlling the on-off of the medium-voltage self-use circuit and the medium-voltage public circuit.

2. The in-plant power system of a thermal power plant according to claim 1, characterized in that: The high-voltage plant transformer unit comprises a plurality of high-voltage plant transformers. The medium-voltage self-use circuit comprises a plurality of medium-voltage self-use bus sections, and the low-voltage side of each high-voltage plant transformer is connected with a plurality of medium-voltage self-use bus sections.

3. The in-plant power system of a thermal power plant according to claim 2, characterized in that: The high-voltage plant transformer unit comprises two high-voltage plant transformers.

4. The in-plant power system of a thermal power plant according to claim 3, characterized in that: The number of medium-voltage self-use bus sections connected on the low-voltage side of the two high-voltage plant transformers is the same and is arranged one by one. The connecting bus unit comprises a plurality of first connecting buses. Any medium-voltage self-use bus section on any high-voltage plant transformer is connected with a corresponding medium-voltage self-use bus section on another high-voltage plant transformer through a first connecting bus, and each first connecting bus is connected with the medium-voltage public circuit. The circuit breaker unit comprises a plurality of circuit breaker assemblies, and each first connecting bus is provided with a circuit breaker assembly.

5. The in-plant power system of a thermal power plant according to claim 4, characterized in that: The circuit breaker assembly comprises two second circuit breakers, one end of the first connecting bus is connected with one medium-voltage self-use bus section through one second circuit breaker, and the other end of the first connecting bus is connected with a corresponding medium-voltage self-use bus section through the other second circuit breaker.

6. The in-plant power system of a thermal power plant according to claim 4, characterized in that: The connecting bus unit further comprises a plurality of second connecting buses, and each first connecting bus is connected with the medium-voltage public circuit through a second connecting bus.

7. The in-plant power system of a thermal power plant according to claim 3, characterized in that: The low-voltage side of each high-voltage plant transformer is connected with two medium-voltage self-use bus sections.

8. The in-plant power system of a thermal power plant according to claim 2, characterized by: The medium-voltage public circuit comprises a plurality of medium-voltage public bus sections, and each medium-voltage self-use bus section is connected with the low-voltage side of the public transformer through a third circuit breaker.

9. The in-plant power system of a thermal power plant according to claim 8, characterized in that: The medium-voltage public circuit comprises two medium-voltage public bus sections.

10. The in-plant power system of a thermal power plant according to claim 9, characterized in that: The connecting bus unit comprises two first connecting buses. The circuit breaker unit comprises two circuit breaker assemblies, and each first connecting bus is provided with a circuit breaker assembly. One first connecting bus is used for connecting one medium-voltage public bus section with a plurality of medium-voltage self-use bus sections, and the other first connecting bus is used for connecting the other medium-voltage public bus section with the remaining medium-voltage self-use bus sections. The circuit breaker assembly is used to control the on-off between the medium-voltage public bus section and each medium-voltage self-use bus section.

Images