Intelligent soft switch topological structure of integrated optical storage medium-voltage grid connection

Abstract

The invention discloses an integrated light storage medium voltage grid-connected intelligent soft switch topological structure, which comprises a medium voltage direct hanging type light storage cascade system, and is characterized in that the medium voltage direct hanging type light storage cascade system is connected with a power supply through a first medium voltage distribution feeder line and a second medium voltage distribution feeder line; the first medium-voltage distribution feeder line and the second medium-voltage distribution feeder line are respectively connected with a first load and a second load. Compared with a traditional full-power-level intelligent soft switch, the three-phase intelligent soft switch converter provided by the invention has the innovation that only part of power of feeder line power flow is adjusted, and the capacity can be far lower than the load level of a connected feeder line, so that the equipment construction cost is remarkably reduced; meanwhile, the device realizes efficient integration of distributed photovoltaic and energy storage through a three-phase optical storage cascade architecture, stabilizes photovoltaic output fluctuation by using energy storage, matches load requirements, and optimizes energy scheduling.

Description

Technical Field

[0001] The present invention belongs to the technical field of power distribution equipment and relates to an intelligent soft switch topology structure for integrating photovoltaic storage and medium-voltage grid connection. Background Art

[0002] In recent years, with the large-scale integration of renewable energy generation, primarily photovoltaics, into medium-voltage distribution networks, the open-loop structure of distribution networks has led to problems such as uneven spatial distribution and difficulty in efficiently utilizing this highly regulated flexible resource. Furthermore, the massive influx of photovoltaics can cause power congestion and reduced flexibility in power flow regulation in distribution networks. Intelligent soft switches can be installed at the end of each feeder to replace traditional tie switches with limited operation times. These switches control the power transmission of connected feeders to adjust the power flow distribution of the distribution network in real time, improving the level of photovoltaic integration in the distribution network. To ensure the reliability of the distribution network, intelligent soft switches are often required to be capable of independently supporting the load of a feeder during a fault. Therefore, current intelligent soft switches of all power levels have high initial investment costs and low capacity utilization.

[0003] In summary, the existing technology has the problems of photovoltaic access leading to power congestion in the distribution network and reduced flexibility in power flow regulation, as well as high cost and low utilization of full-power level intelligent soft switches. Summary of the Invention

[0004] The purpose of the present invention is to provide an intelligent soft switch topology structure for integrated photovoltaic storage and medium-voltage grid connection, which solves the problems in the prior art of photovoltaic access leading to distribution network flow congestion and reduced flow control flexibility, as well as high cost and low utilization of full-power level intelligent soft switches.

[0005] The technical solution adopted by the present invention is an intelligent soft switch topology structure integrating photovoltaic storage and medium-voltage grid connection, including a medium-voltage direct-mounted photovoltaic storage cascade system. The medium-voltage direct-mounted photovoltaic storage cascade system is connected to the power supply through medium-voltage distribution feeder No. 1 and medium-voltage distribution feeder No. 2 respectively. Load No. 1 and load No. 2 are connected to medium-voltage distribution feeder No. 1 and medium-voltage distribution feeder No. 2 respectively.

[0006] The present invention is also characterized in that: The medium-voltage direct-mounted photovoltaic storage cascade system includes a three-phase photovoltaic storage cascade converter, which is connected to the photovoltaic module and the energy storage module respectively. The energy storage module is connected to the three-phase intelligent soft-switching converter. The three-phase photovoltaic storage cascade converter and the three-phase intelligent soft-switching converter are connected to the No. 1 medium-voltage distribution feeder and the No. 2 medium-voltage distribution feeder respectively.

[0007] The three-phase photovoltaic storage cascade converter includes three single-phase photovoltaic storage cascade converters. The single-phase photovoltaic storage cascade converter includes several photovoltaic cascade units and several No. 1 energy storage cascade units. The input ends of the photovoltaic cascade units are connected to the photovoltaic modules through three-phase collection capacitors, and the input ends of the No. 1 energy storage cascade units are connected to the energy storage modules through three-phase collection capacitors. The output ends of the photovoltaic cascade units and the No. 1 energy storage cascade units are connected in series to form the output end of the single-phase photovoltaic storage cascade converter.

[0008] The three-phase intelligent soft-switching converter includes three single-phase intelligent soft-switching converters. The single-phase intelligent soft-switching converter includes several No. 2 energy storage cascade units. The input ends of the No. 2 energy storage cascade units are connected to the energy storage modules through three-phase collection capacitors, and the output ends of the No. 2 energy storage cascade units are connected in series to form the output ends of the single-phase intelligent soft-switching converter.

[0009] The photovoltaic module includes several photovoltaic arrays, the output ends of which are connected to the input ends of the photovoltaic cascade units in three single-phase photovoltaic storage cascade converters through three-phase collection capacitors.

[0010] The energy storage module includes several energy storage batteries, and the output ends of the energy storage batteries are connected to the input end of the No. 1 energy storage cascade unit in the single-phase photovoltaic cascade converter and the input end of the No. 2 energy storage cascade unit in the single-phase intelligent soft-switching converter through three-phase collection capacitors.

[0011] The specific structure of the photovoltaic cascade unit, the No. 1 energy storage cascade unit, and the No. 2 energy storage cascade unit is an isolated DC-AC converter.

[0012] The output end of the three-phase photovoltaic storage cascade converter is connected to the No. 1 medium-voltage distribution feeder, one end of the No. 1 medium-voltage distribution feeder and one end of the No. 2 medium-voltage distribution feeder are respectively connected to the power supply, the other end of the No. 1 medium-voltage distribution feeder and the other end of the No. 2 medium-voltage distribution feeder are connected through the bypass switch S, and the output end of the three-phase intelligent soft-switching converter is respectively connected to the No. 1 medium-voltage distribution feeder and the No. 2 medium-voltage distribution feeder at both ends of the bypass switch S.

[0013] The No. 1 medium voltage distribution feeder is connected to the No. 1 step-up transformer, and the two ends of the No. 1 step-up transformer are connected to the power supply and the No. 1 load respectively.

[0014] The No. 2 medium-voltage distribution feeder is connected to the No. 2 step-up transformer, and the two ends of the No. 2 step-up transformer are connected to the power supply and the No. 2 load respectively.

[0015] The beneficial effects of the present invention are: Reduce equipment costs and improve capacity utilization: By regulating only a portion of the feeder power flow through a three-phase intelligent soft-switching converter, capacity requirements are far lower than with traditional full-power intelligent soft-switching, significantly reducing initial construction investment. Furthermore, the cascaded photovoltaic and energy storage architecture optimizes resource allocation and improves device utilization.

[0016] Enhanced power flow regulation flexibility and energy dispatch efficiency: Efficient integration of distributed photovoltaics and energy storage is achieved, leveraging the energy storage system to smooth intermittent photovoltaic output fluctuations and accurately match load demand. Dynamic adjustment of dual-feeder power flow distribution optimizes energy transmission paths in the distribution network and improves power supply reliability.

[0017] Normalized flexible interconnection and fault emergency support: A breakthrough is made to build flexible "soft connections" between distribution feeders, which can flexibly allocate power during normal operation and quickly switch to emergency power supply mode in fault conditions to provide voltage and power support for power-off loads, significantly improving the grid's fault recovery capabilities.

[0018] Eliminate power imbalance and enhance system stability: The three-phase low-voltage DC input structure is adopted to effectively solve the problem of multi-phase output power imbalance. Combined with isolated DC-AC converter technology, it suppresses harmonic interference and comprehensively improves the stability of grid operation and power quality.

[0019] Multifunctional collaboration and scalability: This system balances fault resilience (such as emergency power supply during line short circuits and power outages) with power quality management (such as voltage fluctuation suppression), supports high-proportion photovoltaic access and coordinated regulation of energy storage, and adapts to the future development needs of intelligent and low-carbon distribution networks.

[0020] Through innovative architectural design, the present invention achieves multi-dimensional performance improvements in the distribution network while reducing costs, providing an efficient solution for the grid connection of new energy sources and the construction of new power systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the structure of the intelligent soft switch topology structure of the medium-voltage grid-connected integrated photovoltaic storage system of the present invention; Figure 2 This is a schematic diagram of the structure of the intelligent soft switch topology structure of the integrated photovoltaic storage medium voltage grid-connected according to the present invention working in a normal power flow control state; Figure 3 This is a schematic diagram of the structure of the intelligent soft switch topology structure of the integrated photovoltaic storage medium voltage grid-connected according to the present invention when a fault occurs in the line near the step-up transformer; Figure 4 This is a structural schematic diagram of the intelligent soft switch topology structure of the integrated photovoltaic storage medium-voltage grid-connected structure of the present invention when a line break fault occurs at the power supply.

[0022] In the figure, 1. Single-phase photovoltaic-storage cascade converter; 101. Photovoltaic cascade unit; 102. Energy storage cascade unit No. 1; 2. Single-phase intelligent soft-switching converter; 201. Energy storage cascade unit No. 2; 3. Photovoltaic module; 301. Photovoltaic array; 4. Energy storage module; 401. Energy storage battery; 5. Medium-voltage distribution feeder No. 1; 6. Medium-voltage distribution feeder No. 2; 7. Load No. 1; 8. Load No. 2; 9. Step-up transformer No. 1; 10. Step-up transformer No. 2; 11. Power supply.

[0023] Specific implementation methods The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] Intelligent soft switching topology for integrated photovoltaic storage medium voltage grid connection, such as Figure 1 As shown, it includes a medium-voltage direct-mounted photovoltaic storage cascade system, which is connected to the power supply 11 through the No. 1 medium-voltage distribution feeder 5 and the No. 2 medium-voltage distribution feeder 6 respectively. The No. 1 medium-voltage distribution feeder 5 and the No. 2 medium-voltage distribution feeder 6 are respectively connected to the No. 1 load 7 and the No. 2 load 8.

[0025] The medium-voltage direct-mounted photovoltaic-storage cascade system includes a three-phase photovoltaic-storage cascade converter, which is respectively connected to a photovoltaic module 3 and an energy storage module 4. The energy storage module 4 is connected to a three-phase intelligent soft-switching converter. The three-phase photovoltaic-storage cascade converter and the three-phase intelligent soft-switching converter are respectively connected to the No. 1 medium-voltage distribution feeder 5 and the No. 2 medium-voltage distribution feeder 6. The three-phase photovoltaic-storage cascade converter includes three single-phase photovoltaic-storage cascade converters 1. The single-phase photovoltaic-storage cascade converter 1 includes a number of photovoltaic cascade units 101 and a number of No. 1 energy storage cascade units 102. The input ends of the photovoltaic cascade units 101 are respectively connected to the photovoltaic modules 3 via three-phase accumulator capacitors. The input ends of the No. 1 energy storage cascade units 102 are respectively connected to the energy storage modules 4 via three-phase accumulator capacitors. The output ends of the photovoltaic cascade units 101 and the No. 1 energy storage cascade units 102 are connected in series to form the output end of the single-phase photovoltaic-storage cascade converter 1. The three-phase intelligent soft-switching converter includes three single-phase intelligent soft-switching converters 2. Each of the single-phase intelligent soft-switching converters 2 includes several second energy storage cascade units 201. The inputs of the second energy storage cascade units 201 are connected to the energy storage module 4 via three-phase accumulator capacitors. The outputs of the second energy storage cascade units 201 are connected in series to form the output of the single-phase intelligent soft-switching converter 2. The photovoltaic module 3 includes several photovoltaic arrays 301. The outputs of the photovoltaic arrays 301 are connected to the inputs of the photovoltaic cascade units 101 in the three single-phase photovoltaic cascade converters 1 via three-phase accumulator capacitors. The energy storage module 4 includes several energy storage batteries 401. The outputs of the energy storage batteries 401 are connected to the inputs of the first energy storage cascade unit 102 in the single-phase photovoltaic cascade converter 1 and the inputs of the second energy storage cascade unit 201 in the single-phase intelligent soft-switching converter 2 via three-phase accumulator capacitors. The specific structure of the photovoltaic cascade unit 101 , the first energy storage cascade unit 102 , and the second energy storage cascade unit 201 is an isolated DC-AC converter.

[0026] The output of the three-phase photovoltaic-storage cascade converter is connected to medium-voltage distribution feeder No. 1 5. One end of medium-voltage distribution feeder No. 1 and one end of medium-voltage distribution feeder No. 2 6 are each connected to power source 11. The other ends of medium-voltage distribution feeder No. 1 and No. 2 6 are connected via a bypass switch S. The output of the three-phase intelligent soft-switching converter is connected to medium-voltage distribution feeder No. 1 5 and medium-voltage distribution feeder No. 2 6 at both ends of bypass switch S. A step-up transformer No. 1 9 is connected to medium-voltage distribution feeder No. 1, and its two ends are connected to power source 11 and load No. 1 7, respectively. A step-up transformer No. 2 10 is connected to medium-voltage distribution feeder No. 2 6, and its two ends are connected to power source 11 and load No. 2 8, respectively.

[0027] The present invention Figure 1 A and B represent the output terminals of the three-phase intelligent soft-switching converter, and N represents the star-connected neutral point of the three-phase photovoltaic-storage cascade converter.

[0028] The present invention proposes a medium-voltage direct-mounted photovoltaic storage cascade system, the core innovation of which is the use of a three-phase intelligent soft-switching converter to achieve partial power regulation and function integration. Compared with the traditional full-power intelligent soft switch, the device only regulates part of the power of the feeder flow, and the capacity can be much lower than the load level of the connected feeder, significantly reducing the equipment volume and construction cost; at the same time, through the three-phase photovoltaic storage cascade architecture, the distributed photovoltaic and energy storage resources at the end of the line are efficiently collected, and the energy storage system is used to smooth the intermittent fluctuations of photovoltaic output in real time, thereby improving the renewable energy absorption capacity. At the system operation level, the device has made a breakthrough in constructing a normalized flexible "soft connection" between distribution feeders - dynamically optimizing the dual feeder flow distribution under normal conditions, quickly switching to emergency mode in the event of a fault, providing voltage and power support for the power-lost load, and having both fault resilience and power quality management capabilities; in addition, its low-voltage DC three-phase collection structure effectively eliminates the problem of multi-phase output power imbalance, suppresses harmonic interference, and comprehensively improves the stability and reliability of power grid operation. This technology balances cost and performance with a low-capacity, highly integrated design, providing an efficient solution for flexible interconnection, new energy consumption, and improved power supply reliability in scenarios with a high proportion of photovoltaic access.

[0029] Example 1 This embodiment proposes an intelligent soft switch topology structure for integrating photovoltaic storage with medium voltage grid connection, such as Figure 1 As shown, it includes a medium-voltage direct-mounted photovoltaic-storage cascade system, which is connected to power source 11 via medium-voltage distribution feeder No. 1 5 and medium-voltage distribution feeder No. 2 6. Load No. 1 7 and load No. 2 8 are connected to medium-voltage distribution feeder No. 1 5 and medium-voltage distribution feeder No. 2 6, respectively. The medium-voltage direct-mounted photovoltaic-storage cascade system includes a three-phase photovoltaic-storage cascade converter, which is connected to photovoltaic module 3 and energy storage module 4, respectively. Energy storage module 4 is connected to a three-phase intelligent soft-switching converter. The three-phase photovoltaic-storage cascade converter and the three-phase intelligent soft-switching converter are connected to medium-voltage distribution feeder No. 1 5 and medium-voltage distribution feeder No. 2 6, respectively.

[0030] Example 2 This embodiment proposes an intelligent soft switch topology structure for integrating photovoltaic storage with medium voltage grid connection, such as Figure 1 As shown, it includes a medium-voltage direct-mounted photovoltaic storage cascade system, which is connected to the power supply 11 through the No. 1 medium-voltage distribution feeder 5 and the No. 2 medium-voltage distribution feeder 6 respectively. The No. 1 medium-voltage distribution feeder 5 and the No. 2 medium-voltage distribution feeder 6 are respectively connected to the No. 1 load 7 and the No. 2 load 8.

[0031] The medium-voltage direct-mounted photovoltaic-storage cascade system includes a three-phase photovoltaic-storage cascade converter, which is respectively connected to a photovoltaic module 3 and an energy storage module 4. The energy storage module 4 is connected to a three-phase intelligent soft-switching converter. The three-phase photovoltaic-storage cascade converter and the three-phase intelligent soft-switching converter are respectively connected to the No. 1 medium-voltage distribution feeder 5 and the No. 2 medium-voltage distribution feeder 6. The three-phase photovoltaic-storage cascade converter includes three single-phase photovoltaic-storage cascade converters 1. The single-phase photovoltaic-storage cascade converter 1 includes a number of photovoltaic cascade units 101 and a number of No. 1 energy storage cascade units 102. The input ends of the photovoltaic cascade units 101 are respectively connected to the photovoltaic modules 3 via three-phase accumulator capacitors. The input ends of the No. 1 energy storage cascade units 102 are respectively connected to the energy storage modules 4 via three-phase accumulator capacitors. The output ends of the photovoltaic cascade units 101 and the No. 1 energy storage cascade units 102 are connected in series to form the output end of the single-phase photovoltaic-storage cascade converter 1.

[0032] Example 3 This embodiment proposes an intelligent soft switch topology structure for integrating photovoltaic storage with medium voltage grid connection, such as Figure 1 As shown, it includes a medium-voltage direct-mounted photovoltaic storage cascade system, which is connected to the power supply 11 through the No. 1 medium-voltage distribution feeder 5 and the No. 2 medium-voltage distribution feeder 6 respectively. The No. 1 medium-voltage distribution feeder 5 and the No. 2 medium-voltage distribution feeder 6 are respectively connected to the No. 1 load 7 and the No. 2 load 8.

[0033] The medium-voltage direct-mounted photovoltaic-storage cascade system includes a three-phase photovoltaic-storage cascade converter, which is respectively connected to a photovoltaic module 3 and an energy storage module 4. The energy storage module 4 is connected to a three-phase intelligent soft-switching converter. The three-phase photovoltaic-storage cascade converter and the three-phase intelligent soft-switching converter are respectively connected to the No. 1 medium-voltage distribution feeder 5 and the No. 2 medium-voltage distribution feeder 6. The three-phase photovoltaic-storage cascade converter includes three single-phase photovoltaic-storage cascade converters 1. The single-phase photovoltaic-storage cascade converter 1 includes a number of photovoltaic cascade units 101 and a number of No. 1 energy storage cascade units 102. The input ends of the photovoltaic cascade units 101 are respectively connected to the photovoltaic modules 3 via three-phase accumulator capacitors. The input ends of the No. 1 energy storage cascade units 102 are respectively connected to the energy storage modules 4 via three-phase accumulator capacitors. The output ends of the photovoltaic cascade units 101 and the No. 1 energy storage cascade units 102 are connected in series to form the output end of the single-phase photovoltaic-storage cascade converter 1. The three-phase intelligent soft-switching converter includes three single-phase intelligent soft-switching converters 2. Each single-phase intelligent soft-switching converter 2 includes several second energy storage cascade units 201. The inputs of the second energy storage cascade units 201 are connected to the energy storage module 4 via three-phase accumulating capacitors. The outputs of the second energy storage cascade units 201 are connected in series to form the output of the single-phase intelligent soft-switching converter 2. The photovoltaic module 3 includes several photovoltaic arrays 301. The outputs of the photovoltaic arrays 301 are connected to the inputs of the photovoltaic cascade units 101 in the three single-phase photovoltaic cascade converters 1 via three-phase accumulating capacitors.

[0034] Example 4 This embodiment proposes an intelligent soft switch topology structure for integrating photovoltaic storage with medium voltage grid connection, such as Figure 1 As shown, it includes a medium-voltage direct-mounted photovoltaic storage cascade system, which is connected to the power supply 11 through the No. 1 medium-voltage distribution feeder 5 and the No. 2 medium-voltage distribution feeder 6 respectively. The No. 1 medium-voltage distribution feeder 5 and the No. 2 medium-voltage distribution feeder 6 are respectively connected to the No. 1 load 7 and the No. 2 load 8.

[0035] The medium-voltage direct-mounted photovoltaic-storage cascade system includes a three-phase photovoltaic-storage cascade converter, which is respectively connected to a photovoltaic module 3 and an energy storage module 4. The energy storage module 4 is connected to a three-phase intelligent soft-switching converter. The three-phase photovoltaic-storage cascade converter and the three-phase intelligent soft-switching converter are respectively connected to the No. 1 medium-voltage distribution feeder 5 and the No. 2 medium-voltage distribution feeder 6. The three-phase photovoltaic-storage cascade converter includes three single-phase photovoltaic-storage cascade converters 1. The single-phase photovoltaic-storage cascade converter 1 includes a number of photovoltaic cascade units 101 and a number of No. 1 energy storage cascade units 102. The input ends of the photovoltaic cascade units 101 are respectively connected to the photovoltaic modules 3 via three-phase accumulator capacitors. The input ends of the No. 1 energy storage cascade units 102 are respectively connected to the energy storage modules 4 via three-phase accumulator capacitors. The output ends of the photovoltaic cascade units 101 and the No. 1 energy storage cascade units 102 are connected in series to form the output end of the single-phase photovoltaic-storage cascade converter 1. The three-phase intelligent soft-switching converter includes three single-phase intelligent soft-switching converters 2. Each of the single-phase intelligent soft-switching converters 2 includes several second energy storage cascade units 201. The inputs of the second energy storage cascade units 201 are connected to the energy storage module 4 via three-phase accumulator capacitors. The outputs of the second energy storage cascade units 201 are connected in series to form the output of the single-phase intelligent soft-switching converter 2. The photovoltaic module 3 includes several photovoltaic arrays 301. The outputs of the photovoltaic arrays 301 are connected to the inputs of the photovoltaic cascade units 101 in the three single-phase photovoltaic cascade converters 1 via three-phase accumulator capacitors. The energy storage module 4 includes several energy storage batteries 401. The outputs of the energy storage batteries 401 are connected to the inputs of the first energy storage cascade unit 102 in the single-phase photovoltaic cascade converter 1 and the inputs of the second energy storage cascade unit 201 in the single-phase intelligent soft-switching converter 2 via three-phase accumulator capacitors. The specific structure of the photovoltaic cascade unit 101 , the first energy storage cascade unit 102 , and the second energy storage cascade unit 201 is an isolated DC-AC converter.

[0036] Example 5 This embodiment proposes an intelligent soft switch topology structure for integrating photovoltaic storage with medium voltage grid connection, such as Figure 1As shown, it includes a medium-voltage direct-mounted photovoltaic-storage cascade system, which is connected to power source 11 via medium-voltage distribution feeder No. 1 5 and medium-voltage distribution feeder No. 2 6. Load No. 1 7 and load No. 2 8 are connected to medium-voltage distribution feeder No. 1 5 and medium-voltage distribution feeder No. 2 6, respectively. The medium-voltage direct-mounted photovoltaic-storage cascade system includes a three-phase photovoltaic-storage cascade converter, which is connected to photovoltaic module 3 and energy storage module 4, respectively. Energy storage module 4 is connected to a three-phase intelligent soft-switching converter. The three-phase photovoltaic-storage cascade converter and the three-phase intelligent soft-switching converter are connected to medium-voltage distribution feeder No. 1 5 and medium-voltage distribution feeder No. 2 6, respectively. The output end of the three-phase photovoltaic storage cascade converter is connected to the No. 1 medium-voltage distribution feeder 5, one end of the No. 1 medium-voltage distribution feeder 5 and one end of the No. 2 medium-voltage distribution feeder 6 are respectively connected to the power supply 11, the other end of the No. 1 medium-voltage distribution feeder 5 and the other end of the No. 2 medium-voltage distribution feeder 6 are connected through a bypass switch S, and the output end of the three-phase intelligent soft-switching converter is respectively connected to the No. 1 medium-voltage distribution feeder 5 and the No. 2 medium-voltage distribution feeder 6 at both ends of the bypass switch S.

[0037] Example 6 This embodiment proposes an intelligent soft switch topology structure for integrating photovoltaic storage with medium voltage grid connection, such as Figure 1 As shown, it includes a medium-voltage direct-mounted photovoltaic storage cascade system, which is connected to the power supply 11 through the No. 1 medium-voltage distribution feeder 5 and the No. 2 medium-voltage distribution feeder 6 respectively. The No. 1 medium-voltage distribution feeder 5 and the No. 2 medium-voltage distribution feeder 6 are respectively connected to the No. 1 load 7 and the No. 2 load 8.

[0038] The medium-voltage direct-mounted photovoltaic-storage cascade system includes a three-phase photovoltaic-storage cascade converter, which is connected to photovoltaic modules 3 and energy storage modules 4, respectively. The energy storage module 4 is connected to a three-phase intelligent soft-switching converter. The three-phase photovoltaic-storage cascade converter and the three-phase intelligent soft-switching converter are respectively connected to medium-voltage distribution feeder No. 1 5 and medium-voltage distribution feeder No. 2 6. The output end of the three-phase photovoltaic-storage cascade converter is connected to medium-voltage distribution feeder No. 1 5. One end of medium-voltage distribution feeder No. 1 and one end of medium-voltage distribution feeder No. 2 6 are respectively connected to power source 11. The other ends of medium-voltage distribution feeder No. 1 and medium-voltage distribution feeder No. 2 6 are connected via a bypass switch S. The output end of the three-phase intelligent soft-switching converter is respectively connected to medium-voltage distribution feeder No. 1 5 and medium-voltage distribution feeder No. 2 6 at both ends of bypass switch S. The No. 1 medium-voltage distribution feeder 5 is connected to a No. 1 step-up transformer 9, whose ends are connected to a power source 11 and a No. 1 load 7, respectively. The No. 2 medium-voltage distribution feeder 6 is connected to a No. 2 step-up transformer 10, whose ends are connected to a power source 11 and a No. 2 load 8, respectively.

[0039] An embodiment of the present invention proposes an intelligent soft-switching topology for integrated photovoltaic and storage medium-voltage grid-connected power. The core of the system is a medium-voltage direct-mounted photovoltaic and storage cascade system, comprising a three-phase photovoltaic and storage cascade converter and a three-phase intelligent soft-switching converter. The output of the three-phase photovoltaic and storage cascade converter is connected to a node on the No. 1 medium-voltage distribution feeder 5. The converter is equipped with m+n low-voltage DC inputs, of which m inputs are connected to m photovoltaic arrays 301 via three-phase merging capacitors, and n inputs are connected to n energy storage batteries 401 via three-phase merging capacitors. The output of the three-phase intelligent soft-switching converter is connected in parallel with a bypass switch S and then connected to the interconnection between the No. 1 and No. 2 medium-voltage distribution feeders 6. The converter is composed of three single-phase intelligent soft-switching converters 2, each of which contains n series-connected No. 2 energy storage cascade units 201. The single-phase photovoltaic cascade converter 1 consists of three photovoltaic cascade units 101 and three No. 1 energy storage cascade units 102 connected in series. The photovoltaic array 301 is connected to the photovoltaic cascade unit of the corresponding phase through a three-phase collection capacitor, and the energy storage battery 401 is simultaneously connected to the photovoltaic cascade unit and the energy storage cascade unit through a three-phase collection capacitor to achieve multi-energy coordinated control.

[0040] The system utilizes a modular design. Both the three-phase photovoltaic-storage cascade converter and the intelligent soft-switching converter are expanded through the cascade of single-phase units to increase voltage levels and capacity. The energy storage battery 401 supports flexible configuration, with the option of using supercapacitors, batteries, or other storage devices, and is compatible with a variety of energy storage technologies. Through topological optimization of the three-phase pooling capacitors, the system achieves distributed access and coordinated power control of photovoltaics and energy storage. Simultaneously, the three-phase intelligent soft-switching converter establishes flexible nodes within the feeder interconnection lines, supporting dynamic power flow regulation and fault emergency response. This system combines high reliability and scalability, making it suitable for grid optimization and energy management in scenarios with high penetration of new energy.

[0041] like Figure 2 As shown, the intelligent soft switch topology structure of the integrated photovoltaic storage medium voltage grid-connected system can adjust the power distribution of the two feeders under normal operating conditions. In this state, the bypass switch S is in the disconnected state, and the load No. 1 7 and the load No. 2 8 are jointly powered by the power supply 11 and the medium voltage direct-mounted photovoltaic storage cascade system proposed by the present invention. The active power flow direction on the medium voltage distribution feeder No. 1 5 and the medium voltage distribution feeder No. 2 6 is indicated by arrows.

[0042] When a short circuit or disconnection occurs in the line near the No. 2 step-up transformer 10, the No. 2 load 8 loses power supply. After the fault is cleared, the bypass switch S is closed, and the medium-voltage direct-mounted photovoltaic storage cascade system can provide emergency power support for the power-lost load, such as Figure 3 As shown, the No. 2 load 8, which is in a power-off state, is supplied with power by the power supply 11 via the No. 1 medium-voltage distribution feeder 5. At the same time, the medium-voltage direct-mounted photovoltaic storage cascade system can also supply power to the No. 2 load 8 according to actual needs. The direction of active power flow on the No. 1 medium-voltage distribution feeder 5 and the No. 2 medium-voltage distribution feeder 6 is indicated by arrows.

[0043] When a line failure occurs at the power source, both load 1 7 and load 2 8 on the two feeders lose power supply. After the fault is cleared, the bypass switch S is closed, and the medium voltage direct-mounted photovoltaic storage cascade system can provide emergency voltage and power support for the power-lost loads, such as Figure 4 At this time, both load 1 7 and load 2 8 are supplied by the medium-voltage direct-mounted PV-storage cascade system, and the direction of active power flow on medium-voltage distribution feeder 1 5 and medium-voltage distribution feeder 2 6 is indicated by arrows.

Claims

1. The intelligent soft switch topology structure of integrated photovoltaic storage medium voltage grid connection is characterized by: The invention comprises a medium-voltage direct-mounted photovoltaic storage cascade system, wherein the medium-voltage direct-mounted photovoltaic storage cascade system is connected to a power source (11) via a No. 1 medium-voltage distribution feeder (5) and a No. 2 medium-voltage distribution feeder (6), and a No. 1 load (7) and a No. 2 load (8) are connected to the No. 1 medium-voltage distribution feeder (5) and the No. 2 medium-voltage distribution feeder (6), respectively.

2. The intelligent soft switch topology structure for integrated photovoltaic and storage medium voltage grid connection according to claim 1 is characterized in that: The medium-voltage direct-mounted photovoltaic storage cascade system comprises a three-phase photovoltaic storage cascade converter, wherein the three-phase photovoltaic storage cascade converter is connected to a photovoltaic module (3) and an energy storage module (4) respectively, the energy storage module (4) is connected to a three-phase intelligent soft-switching converter, and the three-phase photovoltaic storage cascade converter and the three-phase intelligent soft-switching converter are connected to a No. 1 medium-voltage distribution feeder (5) and a No. 2 medium-voltage distribution feeder (6) respectively.

3. The intelligent soft switch topology structure for medium voltage grid connection of integrated photovoltaic storage according to claim 2 is characterized in that: The three-phase photovoltaic storage cascade converter comprises three single-phase photovoltaic storage cascade converters (1), wherein the single-phase photovoltaic storage cascade converter (1) comprises a plurality of photovoltaic cascade units (101) and a plurality of first energy storage cascade units (102), wherein the input ends of the photovoltaic cascade units (101) are respectively connected to the photovoltaic modules (3) via three-phase collection capacitors, and the input ends of the first energy storage cascade units (102) are respectively connected to the energy storage modules (4) via three-phase collection capacitors, and the output ends of the photovoltaic cascade units (101) and the first energy storage cascade units (102) are connected in series to form the output end of the single-phase photovoltaic storage cascade converter (1).

4. The intelligent soft switch topology structure for medium voltage grid connection of integrated photovoltaic and energy storage according to claim 3 is characterized in that: The three-phase intelligent soft-switching converter comprises three single-phase intelligent soft-switching converters (2), the single-phase intelligent soft-switching converter (2) comprises a plurality of second energy storage cascade units (201), the input ends of the second energy storage cascade units (201) are respectively connected to the energy storage module (4) via three-phase collection capacitors, and the output ends of the second energy storage cascade units (201) are connected in series to form the output end of the single-phase intelligent soft-switching converter (2).

5. The intelligent soft switch topology structure for medium voltage grid connection of integrated photovoltaic storage according to claim 4 is characterized in that: The photovoltaic module (3) comprises a plurality of photovoltaic arrays (301), the output ends of the photovoltaic arrays (301) being connected to the input ends of the photovoltaic cascade units (101) in three single-phase photovoltaic storage cascade converters (1) via three-phase collection capacitors.

6. The intelligent soft switch topology structure for medium voltage grid connection of integrated photovoltaic and energy storage according to claim 5 is characterized in that: The energy storage module (4) includes a plurality of energy storage batteries (401), and the output ends of the energy storage batteries (401) are respectively connected to the input end of the first energy storage cascade unit (102) in the single-phase photovoltaic cascade converter (1) and the input end of the second energy storage cascade unit (201) in the single-phase intelligent soft-switching converter (2) through three-phase collection capacitors.

7. The intelligent soft switch topology structure for medium voltage grid connection of integrated photovoltaic and energy storage according to claim 6 is characterized in that: The photovoltaic cascade unit (101), the first energy storage cascade unit (102), and the second energy storage cascade unit (201) are specifically structured as isolated DC-AC converters.

8. The intelligent soft switch topology structure for medium voltage grid connection of integrated photovoltaic and energy storage according to claim 2 is characterized in that: The output end of the three-phase photovoltaic storage cascade converter is connected to the No. 1 medium voltage distribution feeder (5), one end of the No. 1 medium voltage distribution feeder (5) and one end of the No. 2 medium voltage distribution feeder (6) are respectively connected to the power supply (11), the other end of the No. 1 medium voltage distribution feeder (5) and the other end of the No. 2 medium voltage distribution feeder (6) are connected through a bypass switch S, and the output end of the three-phase intelligent soft switching converter is respectively connected to the No. 1 medium voltage distribution feeder (5) and the No. 2 medium voltage distribution feeder (6) at both ends of the bypass switch S.

9. The intelligent soft switch topology structure for medium voltage grid connection of integrated photovoltaic and energy storage according to claim 8 is characterized in that: The No. 1 medium voltage distribution feeder (5) is connected to a No. 1 step-up transformer (9), and both ends of the No. 1 step-up transformer (9) are respectively connected to a power source (11) and a No. 1 load (7).

10. The intelligent soft switch topology structure for medium voltage grid connection of integrated photovoltaic and energy storage according to claim 8, characterized in that: The No. 2 medium voltage distribution feeder (6) is connected to a No. 2 step-up transformer (10), and both ends of the No. 2 step-up transformer (10) are respectively connected to a power source (11) and a No. 2 load (8).

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