Static and rotary power supply cooperative emergency power supply equipment and multi-mode control method thereof

Abstract

The invention provides static and rotating power supply cooperative emergency power supply equipment and a multi-mode control method thereof.The emergency power supply equipment comprises a diesel generator, a direct current bus filter capacitor and a plurality of DC-AC three-phase inversion modules and further comprises a three-phase switch k1, the output end of the diesel generator is connected with the three-phase switch k1, two paths of three-phase lines are led out of the three-phase switch k1, and the two paths of three-phase lines are connected with the output end of the diesel generator; wherein one path of three-phase line serves as a primary power supply end of the emergency power supply equipment, the other path of three-phase line is connected with the alternating current side of one DC-AC three-phase inversion module, and the DC sides of the DC-AC three-phase inversion module and the other DC-AC three-phase inversion modules are connected with a DC bus filter capacitor. And the alternating current sides of the other DC-AC three-phase inversion modules are respectively used as secondary power supply ends of the emergency power supply equipment. According to the invention, power electronic devices and the capacity of the existing multi-port emergency power supply equipment can be effectively reduced.

Description

Technical Field

[0001] The present invention relates to the field of electric power grid control technology, and in particular to a static and rotating power supply cooperative emergency power supply equipment and a multi-mode control method thereof. Background Art

[0003] Emergency power supply equipment with mobile properties is one of the main means to achieve emergency power supply. However, due to multiple constraints such as loadable energy capacity and single port grid connection, traditional emergency power supply equipment has prominent problems such as weak power supply support capacity, high energy consumption, and single function. Figure 1 As shown. Fixed-installed flexible interconnection devices can optimize local power flow and power supply quality, but the dual uncertainty of new energy and load power causes the equipment to be idle for a long time, with high investment costs and low returns on a large scale. For this reason, some scholars have proposed combining traditional emergency power supply equipment with flexible interconnection devices to build multi-port emergency power supply equipment to achieve complementary advantages between the two. Multi-port emergency power supply equipment such as Figure 2 shown.

[0004] However, the existing multi-port emergency power supply equipment adopts the topology of AC-DC rectification followed by DC-AC inversion, which requires more power semiconductor devices, and the power supply of the diesel generator must flow completely through the power electronic equipment before being supplied to the load, which increases the device selection and capacity of the power electronic equipment. Therefore, the existing multi-port emergency power supply equipment still has the disadvantages of a large number of devices, large power electronic port capacity, low utilization rate, and high investment cost. Summary of the invention

[0005] In order to solve the problems of large number of devices and large power electronic port capacity in existing multi-port emergency power supply equipment, the present invention proposes a stationary and rotating power supply cooperative emergency power supply equipment and a multi-mode control method thereof.

[0006] In order to solve the above technical problems, the present invention adopts the following technical method: a static and rotating power supply coordinated emergency power supply equipment, including a diesel generator, a DC bus filter capacitor and multiple DC-AC three-phase inverter modules, and also including a three-phase switch k1. The output end of the diesel generator is connected to the three-phase switch k1, and the three-phase switch k1 leads to two three-phase lines, one of which is used as the primary power supply end of the emergency power supply equipment, and the other three-phase line is connected to the AC side of a DC-AC three-phase inverter module. The DC sides of the DC-AC three-phase inverter module and the remaining DC-AC three-phase inverter modules are all connected to the DC bus filter capacitor, and the AC sides of the remaining DC-AC three-phase inverter modules are respectively used as the secondary power supply ends of the emergency power supply equipment.

[0007] Furthermore, the number of the DC-AC three-phase inverter modules is two, the DC sides of the two DC-AC three-phase inverter modules are connected to the DC bus filter capacitor, the AC side of one DC-AC three-phase inverter module is connected to the three-phase switch k1, and the AC side of the other DC-AC three-phase inverter module serves as the secondary power supply end of the emergency power supply equipment.

[0008] As another aspect of the present invention, a multi-mode control method of the aforementioned emergency power supply equipment of the coordinated type of stationary and rotating power sources comprises: Step S1, compare the distance between two stations L Length of cables carried by emergency power supply equipment The size of , then go to step S2; if , then go to step S3; Step S2, detecting the power failure state of the two substations; if both substations lose power, the emergency power supply equipment is connected to the two substations through the primary power supply terminal and the secondary power supply terminal, and works in mode 1; if only one of the two substations loses power, the emergency power supply equipment is connected to the substation with power through the primary power supply terminal and the substation with power failure through the secondary power supply terminal, and works in mode 2; if both substations have power, the emergency power supply equipment is connected to the two substations through the primary power supply terminal and the secondary power supply terminal, and works in mode 3; Step S3, detecting the power failure status of the two substations; if both substations lose power, the emergency power supply equipment is connected to the substation with the most power failure through the primary power supply terminal, and works in mode 4; if only one of the two substations loses power, the emergency power supply equipment is connected to the power failure substation through the primary power supply terminal, and works in mode 4; if both substations have power, the emergency power supply equipment is connected to any substation through the primary power supply terminal, and works in mode 5; Mode 1, multi-station support: the three-phase switch k1 is closed, the DC-AC three-phase inverter module connected to the three-phase switch k1 adopts DC voltage stabilization control, and the other DC-AC three-phase inverter module adopts AC voltage frequency support control; Mode 2, area power supply support: the three-phase switch k1 is disconnected, the DC-AC three-phase inverter module connected to the three-phase switch k1 adopts DC voltage stabilization control, and the other DC-AC three-phase inverter module adopts AC voltage frequency support control; Mode 3, multi-station power flow control: the three-phase switch k1 is disconnected, the DC-AC three-phase inverter module connected to the three-phase switch k1 adopts DC voltage stabilization control, and the other DC-AC three-phase inverter module adopts active and reactive power control; Mode 4, single-station support: the three-phase switch k1 is closed, and the DC-AC three-phase inverter module connected to the three-phase switch k1 adopts DC voltage stabilization control and compensates for the reactive power of the access station; Mode 5, single-station power management: the three-phase switch k1 is disconnected, and the DC-AC three-phase inverter module connected to the three-phase switch k1 adopts power quality management control and compensates for the reactive power of the access station.

[0009] The present invention provides a static and rotating power supply cooperative emergency power supply equipment and a multi-mode control method thereof. Based on the idea that part of the power flows through the power electronic equipment, the present invention constructs a new type of emergency power generation vehicle in the form of a static power electronic equipment and a rotating diesel generator in parallel. Under the premise of ensuring all functions of the traditional multi-terminal mobile emergency vehicle, the power electronic devices and capacity of the existing multi-port emergency power supply equipment are effectively reduced, the utilization rate of the device is improved, and the investment cost is reduced. At the same time, a multi-mode control method is designed for the proposed emergency power supply equipment based on static and rotating heterogeneous power supplies to meet the operation and control requirements in different scenarios and provide effective support for the equipment work. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is the topological structure diagram of the traditional emergency power supply equipment; Figure 2 This is a topological diagram of the traditional multi-port emergency power supply equipment; Figure 3 A topological diagram of the emergency power supply equipment with coordinated stationary and rotating power supplies provided by the present invention; Figure 4 A flow chart of a multi-mode control method for a stationary and rotating power supply cooperative emergency power supply equipment provided by the present invention; Figure 5 Schematic diagram of the operation mode of the emergency power supply equipment in the present invention (wherein (a) is a schematic diagram of the emergency power supply equipment operating in mode 1; (b) is a schematic diagram of the emergency power supply equipment operating in mode 2; (c) is a schematic diagram of the emergency power supply equipment operating in mode 3; (d) is a schematic diagram of the emergency power supply equipment operating in mode 4; (e) is a schematic diagram of the emergency power supply equipment operating in mode 5); Figure 6 This is a schematic diagram of the operation of Mode 1 in an embodiment of the present invention; Figure 7 The following are simulation waveforms of mode 1 in the embodiment of the present invention (wherein (a) is the load power waveform of the substations 1 and 2; (b) is the power waveform of the diesel generator and the DC-AC three-phase inverter modules 1 and 2; (c) is the DC side voltage waveform; (d) is the three-phase voltage waveform of the DC-AC three-phase inverter module 2 on the AC side); Figure 8 This is a schematic diagram of the operation of Mode 2 in an embodiment of the present invention; Fig. 9The following are simulation waveforms of mode 2 in the embodiment of the present invention (wherein (a) is the load power waveform of substations 1 and 2; (b) is the power waveform of DC-AC three-phase inverter modules 1 and 2; (c) is the DC side voltage waveform; (d) is the three-phase voltage waveform of the AC side of DC-AC three-phase inverter module 2); Fig.10 This is a schematic diagram of operation mode 3 in an embodiment of the present invention; Fig.11 The following are simulation waveforms of mode 3 in the embodiment of the present invention (wherein (a) is the load power waveform of the substations 1 and 2; (b) is the power waveform of the DC-AC three-phase inverter modules 1 and 2; (c) is the DC side voltage waveform); Fig.12 This is a schematic diagram of operation of Mode 4 in an embodiment of the present invention; Fig.13 The following are simulation waveforms of mode 4 in the embodiment of the present invention (wherein (a) is the load power waveform of area 3; (b) is the active and reactive power waveform of the diesel generator; (c) is the active and reactive power waveform of the DC-AC three-phase inverter module 1; (d) is the DC side voltage waveform; (e) is the three-phase voltage waveform of the diesel generator); Fig.14 This is a schematic diagram of the operation of Mode 5 in an embodiment of the present invention; Fig.15 The following are simulation waveforms of mode 5 in an embodiment of the present invention (wherein (a) is the load power waveform of substation 3; (b) is the active and reactive power waveform of DC-AC three-phase inverter module 1; (c) is the DC side voltage waveform; (d) is the three-phase current waveform of substation 3). DETAILED DESCRIPTION

[0011] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with embodiments and drawings. The contents mentioned in the implementation modes are not intended to limit the present invention.

[0012] like Figure 3As shown, the static and rotating power supply cooperative emergency power supply equipment provided by the present invention includes a diesel generator G, a DC bus filter capacitor C, a three-phase switch k1, a DC-AC three-phase inverter module M1 and a DC-AC three-phase inverter module M2. The output end of the diesel generator G is connected to the three-phase switch k1, and the three-phase switch k1 leads to two three-phase lines, one of which is used as the primary power supply end of the emergency power supply equipment and can be directly connected to the distribution network to supply power to the load, and the other three-phase line is connected to the AC side of the DC-AC three-phase inverter module M1. The DC sides of the DC-AC three-phase inverter module M1 and the DC-AC three-phase inverter module M2 are both connected to the DC bus filter capacitor C, and the AC side of the DC-AC three-phase inverter module M2 is used as the secondary power supply end of the emergency power supply equipment. The access position of the secondary power supply end is confirmed according to the operation mode.

[0013] The stationary and rotating power supply cooperative emergency power supply equipment provided by the present invention adopts a multi-mode control method, such as Figure 4 As shown, the method includes: Step S1, compare the area The distance between Length of cables carried by emergency power supply equipment The size of , then the emergency power supply equipment can connect both areas to enter the multi-area interconnection state and go to step S2; if , the emergency power supply equipment can only be connected to one area, enter the single area access state, and go to step S3.

[0014] Step S2, detection area If the power failure state If power is lost, If there is electricity, is 1; if the area If power is lost, If there is electricity, is 1; according to The value of determines the operating mode: 1) If If it is 00, the emergency power supply equipment is connected to two areas through the primary power supply terminal and the secondary power supply terminal, and works in mode 1. Mode 1 is a multi-area support mode. Figure 5 (a), in this mode, the three-phase switch k1 is closed, the diesel generator G provides energy for the substation, the primary power supply end supplies power to the substation with power failure, and the DC-AC three-phase inverter module M1 connected to the three-phase switch k1 uses DC voltage stabilization control (Udc-Q control) to stabilize the DC capacitor voltage and supply power to the DC-AC three-phase inverter module M2 at the same time. The DC-AC three-phase inverter module M2 uses AC voltage frequency support control (VF control) to supply power to the substation with power failure.

[0015] 2) If If it is 01 or 10, the emergency power supply equipment is connected to the station area through the primary power supply terminal and to the lost station area through the secondary power supply terminal, and works in mode 2. Mode 2 is the area transfer support mode. Figure 5 (b), in this mode, the three-phase switch k1 is disconnected, the diesel generator G is shut down, and the DC-AC three-phase inverter module M1 connected to the three-phase switch k1 adopts DC voltage stabilization control. The radio area with power supplies the DC-AC three-phase inverter module M2 through the primary power supply end and the DC-AC three-phase inverter module M1 in turn, and the DC-AC three-phase inverter module M2 then adopts AC voltage frequency support control to supply power to the lost radio area; here, it is worth mentioning that, under normal circumstances, when working in mode 2, the radio area with power can provide sufficient power for the lost radio area, but in order to ensure that the lost radio area can obtain sufficient power under any circumstances, the present invention can first determine whether the power that the radio area can provide is sufficient to support the lost radio area. If so, the above-mentioned method is adopted, the three-phase switch k1 is disconnected, the diesel generator G is shut down, and the power required by the lost radio area is all transferred from the radio area with power. If not, the three-phase switch k1 is closed, and the radio area with power transfers all the power it can provide to the lost radio area, and the remaining part of the power required by the lost radio area is provided by the diesel generator G.

[0016] 3) If If it is 11, the emergency power supply equipment is connected to two areas through the primary power supply terminal and the secondary power supply terminal, and works in mode 3. Mode 3 is a multi-area power flow control mode. Figure 5 (c) In this mode, the three-phase switch k1 is disconnected, the diesel generator G is shut down, and the DC-AC three-phase inverter module M1 connected to the three-phase switch k1 uses DC voltage stabilization control to stabilize the DC capacitor voltage. The DC-AC three-phase inverter module M1 is directly connected to one of the station areas and can supply power to the DC-AC three-phase inverter module M2. The DC-AC three-phase inverter module M2 uses active and reactive power control (PQ control) to regulate the power flow between stations.

[0017] Step S3, detection area If the power failure state If power is lost, If there is electricity, is 1; if the area If power is lost, If there is electricity, is 1; according to The value of determines the operating mode: 1) If If it is 00, the emergency power supply equipment is connected to the area with the most power outages through the primary power supply terminal and works in mode 4, which is the single area support mode. Figure 5(d) In this mode, the three-phase switch k1 is closed, and the diesel generator G provides energy for the substation. Specifically, the primary power supply end supplies power to the access substation, and the DC-AC three-phase inverter module M1 connected to the three-phase switch k1 uses DC voltage stabilization control to stabilize the DC capacitor voltage and compensate for the reactive power of the access substation.

[0018] 2) If If it is 01 or 10, the emergency power supply equipment is connected to the power outage area through the primary power supply terminal and works in mode 4 (same as mode 4 above).

[0019] 3) If If it is 11, the emergency power supply equipment is connected to any area through the primary power supply terminal and works in mode 5. Mode 5 is the single area power management mode. Figure 5 (e) In this mode, the three-phase switch k1 is disconnected, the diesel generator G is turned off, and the DC-AC three-phase inverter module M1 connected to the three-phase switch k1 adopts power quality management control (THD control) to stabilize the DC capacitor voltage and compensate for the reactive power and power quality of the access area.

[0020] In order to further verify the effectiveness and superiority of the present invention, the present invention builds a two-port emergency power supply equipment simulation model based on the Matlab / simulink simulation platform. Figure 3 , the simulation parameters are shown in Table 1: , (1) Mode 1 simulation verification The emergency power supply equipment is set to be connected to the substations 1 and 2, and both substations 1 and 2 lose power. , and both areas 1 and 2 lose power At this time, according to the operation mode switching strategy, the generator car is judged to work in mode 1 multi-station area support. The three-phase switch k1 is closed, the diesel generator is started, the DC-AC three-phase inverter module 1 adopts Udc-Q control, and the DC-AC three-phase inverter module 2 adopts VF control. The system architecture is as follows Figure 6 As shown, the simulation waveform is as follows Figure 7 shown.

[0021] Figure 7 (a) is the load power of areas 1 and 2, and the load power of area 1 50kW, load in area 2 It is -20kW. Figure 7 (b) is the diesel generator power , DC-AC three-phase inverter module 1 power , DC-AC three-phase inverter module 2 power , DC-AC three-phase inverter module 2 uses VF control to absorb the remaining power of area 2 -20kW and transfer it to area 1, thereby reducing the output power of the diesel generator to 30kW. The DC side voltage waveform is as follows Figure 7 As shown in (c), the three-phase voltage on the AC side of the DC-AC three-phase inverter module 2 Waveform Figure 7 As shown in (d), the voltage on the AC and DC sides is stable during the whole process.

[0022] (2) Mode 2 simulation verification The emergency power supply equipment is set to be connected to the substations 1 and 2, and substation 1 has power, while substation 2 has no power. ,and At this time, according to the operation mode switching strategy, the generator car is judged to work in mode 2 area transfer support. The three-phase switch k1 is disconnected, the diesel generator is turned off, the DC-AC three-phase inverter module 1 adopts Udc-Q control, and the DC-AC three-phase inverter module 2 adopts VF control. The system architecture is as follows Figure 8 As shown, the simulation waveform is as follows Fig. 9 shown.

[0023] Fig. 9 (a) is the load power of areas 1 and 2, and the load power of area 1 50kW, load in area 2 It is -20kW. Fig. 9 (b) is the power of DC-AC three-phase inverter module 1 , DC-AC three-phase inverter module 2 power , DC-AC three-phase inverter module 2 uses VF control to absorb the remaining power of area 2 -20kW, and transfers it to area 1 through DC-AC three-phase inverter module 1. The DC side voltage waveform is as follows Fig. 9 As shown in (c), the three-phase voltage on the AC side of the DC-AC three-phase inverter module 2 Waveform Fig. 9 As shown in (d), the voltage on the AC and DC sides is stable during the whole process.

[0024] (3) Mode 3 simulation verification The emergency power supply equipment is set to be connected to the substations 1 and 2, and both substations 1 and 2 have power. ,and At this time, according to the operation mode switching strategy, the generator car is judged to work in mode 3 power flow control. The three-phase switch k1 is disconnected, the diesel generator is turned off, the DC-AC three-phase inverter module 1 adopts Udc-Q control, and the DC-AC three-phase inverter module 2 adopts PQ control. The system architecture is as follows Fig.10 As shown, the simulation waveform is as follows Fig.11 shown.

[0025] Fig.11 (a) is the load power of areas 1 and 2, and the load power of area 1 50kW, load in area 2 It is -20kW. Fig.11 (b) is the power of DC-AC three-phase inverter module 1 , DC-AC three-phase inverter module 2 power , DC-AC three-phase inverter module 2 adopts PQ control to absorb the remaining power of area 2 -20kW, and transfers it to area 1 through DC-AC three-phase inverter module 1. The DC side voltage waveform is as follows Fig.11 As shown in (c), the DC side voltage is stable during the whole process.

[0026] (4) Mode 4 simulation verification The emergency power supply equipment is set to be connected to area 3, and area 3 loses power. Since the length of the carrying cable is less than the distance between areas 2 and 3 , and power outage in area 3 At this time, according to the operation mode switching strategy, the generator car is judged to work in mode 4 single-station area support. The three-phase switch k1 is closed, the diesel generator is started, and the DC-AC three-phase inverter module 1 uses Udc-Q control to stabilize the DC side voltage and compensate for reactive power. The system architecture is as follows Fig.12 As shown, the simulation waveform is as follows Fig.13 shown.

[0027] Fig.13 (a) is the active and reactive power of load in area 3. 40kW, reactive load It is 20kvar. Fig.13 (b) is the active power output of the diesel generator Reactive Power , the diesel generator only generates 40kW of active power, and the reactive power is provided by the DC-AC three-phase inverter module 1, such as Fig.13 (c) is shown. The DC side voltage waveform is as follows Fig.13 (d) shows the diesel generator output voltage Waveform Fig.13 As shown in (e), the DC side voltage and the station area voltage remain stable during the whole process.

[0028] (5) Mode 5 simulation verification The emergency power supply equipment is set to be connected to area 3, and area 3 has power. Since the length of the carrying cable is shorter than the distance between areas 2 and 3 , and there is electricity in area 3 At this time, according to the operation mode switching strategy, the generator car is judged to work in mode 5 single-station power management. The three-phase switch k1 is disconnected, the diesel generator is turned off, and the DC-AC three-phase inverter module 1 uses THE control to stabilize the DC side voltage while compensating for reactive power and power quality. The system architecture is as follows Fig.14 As shown, the simulation waveform is as follows Fig.15 shown.

[0029] Fig.15 (a) is the active and reactive power of load in area 3. 40kW, reactive load It is 20kvar. Fig.15 (b) is the active power output of the DC-AC three-phase inverter module 1 Reactive Power , compensate the reactive power of area 3 20kvar, and control the harmonic three-phase current of area 3 ,like Fig.15 (d) is shown. The DC side voltage waveform is as follows Fig.15 As shown in (c), the DC side voltage remains stable during the whole process.

[0030] It can be seen that the static and rotating power supply cooperative emergency power supply equipment and its multi-mode control method proposed in the present invention can reduce the number of equipment components, reduce costs, and improve operating efficiency on the basis of meeting all the functions of the existing multi-port emergency power supply equipment. It is worth noting that the present invention only analyzes the emergency power supply equipment with two ports as an example. The present invention can also be applied to multi-port (greater than 2) and other types of DC-AC three-phase full-bridge module structures. When applied in actual engineering, the emergency power generation vehicle can be modified according to the actual port requirements and module structure.

[0031] The above embodiments are preferred implementation schemes of the present invention. In addition, the present invention may also be implemented in other ways. Any obvious replacement without departing from the concept of the present technical solution is within the protection scope of the present invention.

[0032] In order to make it easier for ordinary technicians in the field to understand the improvements of the present invention over the prior art, some drawings and descriptions of the present invention have been simplified, and for the sake of clarity, some other elements are omitted in this application document. Ordinary technicians in the field should realize that these omitted elements may also constitute the content of the present invention.

Claims

1. The emergency power supply equipment with coordinated static and rotating power sources includes a diesel generator, a DC bus filter capacitor and multiple DC-AC three-phase inverter modules, characterized in that: It also includes a three-phase switch k1. The output end of the diesel generator is connected to the three-phase switch k1. The three-phase switch k1 leads out two three-phase lines, one of which is used as the primary power supply end of the emergency power supply equipment, and the other three-phase line is connected to the AC side of a DC-AC three-phase inverter module. The DC sides of the DC-AC three-phase inverter module and the remaining DC-AC three-phase inverter modules are connected to the DC bus filter capacitor, and the AC sides of the remaining DC-AC three-phase inverter modules are respectively used as the secondary power supply ends of the emergency power supply equipment.

2. The stationary and rotating power supply coordinated emergency power supply equipment according to claim 1 is characterized in that: There are two DC-AC three-phase inverter modules, the DC sides of the two DC-AC three-phase inverter modules are connected to the DC bus filter capacitor, the AC side of one DC-AC three-phase inverter module is connected to the three-phase switch k1, and the AC side of the other DC-AC three-phase inverter module serves as the secondary power supply end of the emergency power supply equipment.

3. The multi-mode control method for emergency power supply equipment coordinated with stationary and rotating power sources according to claim 2, characterized in that: include: Step S1, compare the distance between two stations L Length of cables carried by emergency power supply equipment The size of , then go to step S2; if , then go to step S3; Step S2, detecting the power failure state of the two substations; if both substations lose power, the emergency power supply equipment is connected to the two substations through the primary power supply terminal and the secondary power supply terminal, and works in mode 1; if only one of the two substations loses power, the emergency power supply equipment is connected to the substation with power through the primary power supply terminal and the substation with power failure through the secondary power supply terminal, and works in mode 2; if both substations have power, the emergency power supply equipment is connected to the two substations through the primary power supply terminal and the secondary power supply terminal, and works in mode 3; Step S3, detecting the power failure status of the two substations; if both substations lose power, the emergency power supply equipment is connected to the substation with the most power failure through the primary power supply terminal, and works in mode 4; if only one of the two substations loses power, the emergency power supply equipment is connected to the power failure substation through the primary power supply terminal, and works in mode 4; if both substations have power, the emergency power supply equipment is connected to any substation through the primary power supply terminal, and works in mode 5; Mode 1, multi-station support: the three-phase switch k1 is closed, the DC-AC three-phase inverter module connected to the three-phase switch k1 adopts DC voltage stabilization control, and the other DC-AC three-phase inverter module adopts AC voltage frequency support control; Mode 2, area power supply support: the three-phase switch k1 is disconnected, the DC-AC three-phase inverter module connected to the three-phase switch k1 adopts DC voltage stabilization control, and the other DC-AC three-phase inverter module adopts AC voltage frequency support control; Mode 3, multi-station power flow control: the three-phase switch k1 is disconnected, the DC-AC three-phase inverter module connected to the three-phase switch k1 adopts DC voltage stabilization control, and the other DC-AC three-phase inverter module adopts active and reactive power control; Mode 4, single-station support: the three-phase switch k1 is closed, and the DC-AC three-phase inverter module connected to the three-phase switch k1 adopts DC voltage stabilization control and compensates for the reactive power of the access station; Mode 5, single-station power management: the three-phase switch k1 is disconnected, and the DC-AC three-phase inverter module connected to the three-phase switch k1 adopts power quality management control and compensates for the reactive power of the access station.

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