Household new energy distributed photovoltaic power station system and fault repair method thereof

Abstract

The invention discloses a household new energy distributed photovoltaic power station system and a fault repairing method thereof. The system comprises a photovoltaic module array, a string inverter unit, a grid-connected cabinet, a communication cabinet, a cloud platform and a power grid. The photovoltaic module array comprises a plurality of photovoltaic modules, and the direct current output end of each photovoltaic module is connected to the direct current input end of the corresponding string inverter through the corresponding direct current side electrical on-off device; the string inverter unit comprises a plurality of string inverters and is used for converting direct current input into alternating current output, alternating current output ends of the string inverters are respectively connected to the grid-connected cabinet through the alternating current side electrical on-off device, and the grid-connected cabinet is connected to a power grid through an alternating current line; the string inverters are further connected to the communication cabinet through communication lines, the communication cabinet is used for collecting, managing and uploading operation data of the string inverters, and the communication cabinet carries out data interaction with the cloud platform through the communication lines. According to the invention, the reliability, maintainability and operation efficiency of the photovoltaic power station can be improved.

Description

Technical Field

[0001] This invention relates to the field of distributed photovoltaic power station technology, specifically to a household new energy distributed photovoltaic power station system and its fault repair method. Background Technology

[0002] With the development of distributed photovoltaic power stations and microgrid systems, remote monitoring and intelligent fault diagnosis technologies have been widely applied in this field. As an emerging power supply system, the communication architecture of distributed new energy systems has gradually transformed from a three-layer distribution network structure to a multi-layer structure. To meet the needs of the cloud, equipment, and users, most distributed new energy communication systems basically adopt the traditional layered structure of the distribution network, namely, the equipment layer, the centralized control layer, and the remote control layer. The equipment layer collects electrical characteristics of equipment based on sensors; the centralized control layer collects operating data from various devices and sends it to the cloud, managing the equipment according to certain strategies when receiving commands from the cloud; the remote control layer analyzes the system's operating status based on the data uploaded by the centralized control layer, records the operating data, and performs power allocation and fault maintenance management based on the operating status.

[0003] Currently, the operation and maintenance management of distributed photovoltaic (PV) power plants mainly relies on cloud-based fault prediction and equipment protection threshold determination. When a major fault occurs in a piece of equipment in a PV power plant, the inverter within the plant will enter a fault state and stop operating. At this time, the cloud will alert maintenance personnel to perform maintenance and repair based on the fault information fed back by the device. However, some major faults in equipment cannot self-recover, leading to direct equipment shutdown. To resolve such situations, owners can only wait for professional personnel to perform on-site maintenance. During the period before maintenance personnel arrive on-site, the entire power plant will operate under conditions outside its design power. Especially in some microgrid systems, the control strategy will change during this time, severely impacting the power plant's operating efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a household new energy distributed photovoltaic power station system and its fault repair method in view of the above-mentioned problems of the prior art, so as to realize the fault repair / self-healing of the internal equipment of the new energy power station and ensure the stable operation of the photovoltaic power station.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A residential distributed photovoltaic power station system includes: Photovoltaic module arrays, string inverter units, grid-connected cabinets, communication cabinets, cloud platforms, and power grids; The photovoltaic module array includes a number of photovoltaic modules, wherein the DC output terminal of each photovoltaic module is connected to the DC input terminal of the corresponding string inverter via a corresponding DC side electrical switching device; The string inverter unit includes multiple string inverters for converting DC input to AC output. The AC output terminal of each string inverter is connected to the grid-connected cabinet via an AC side electrical switching device. The grid-connected cabinet is connected to the power grid via an AC line. Each string inverter is also connected to a communication cabinet via a communication line. The communication cabinet is used to collect, manage, and upload the operating data of the string inverters. The communication cabinet interacts with the cloud platform via the communication line.

[0006] Furthermore, the string inverter unit also includes a backup string inverter. The DC input terminal of the backup string inverter is connected to the DC output terminal of each photovoltaic module through multiple DC-side switches, and the AC output terminal is connected to the AC output terminal of each string inverter through multiple AC-side switches. The backup string inverter is used to put into operation when the string inverter fails.

[0007] Furthermore, a DC-side electrical switching device is provided before the DC input terminal of the standby string inverter, and an AC-side electrical switching device is provided after the AC output terminal of the standby string inverter.

[0008] Furthermore, each string inverter transmits data to the communication cabinet via an RS485 communication line or wireless communication, and the communication cabinet transmits data to the cloud platform via optical fiber or wireless communication.

[0009] Furthermore, the string inverters communicate and network with each other through Mesh technology. Based on the installation location and communication signal strength of each string inverter, the string inverters in the power station are divided into one or more local area networks. Each local area network includes a master device responsible for external communication and several slave devices. The communication topology logic in the local area network adopts a combination of ring topology and star topology for wireless transmission and fault location of equipment within the local area network.

[0010] A fault repair method based on a residential renewable energy distributed photovoltaic power station system includes the following steps: When the power station is running, the inverters in each string within the photovoltaic power station system communicate and form a network. Within the communication network, each inverter in each string is initialized according to the communication configuration file issued by the cloud platform when it first starts running. When the power station is running, the electrical switching devices controlling the DC and AC sides of each string inverter are in the closed state, and the DC side switches of the standby string inverter are in the closed state and the AC side switches are in the open state, so that the standby string inverter works in the standby state. The cloud platform monitors the operating status of each string inverter in real time based on the operating status data periodically reported by the master device in the local area network composed of each string inverter. If a string inverter is detected to have failed and the failed device is a slave device, the platform determines the location of the failed device in the power grid and decides whether to perform a fault repair operation based on the fault level. If the failed device is a master device, the platform re-networks the inverter and decides whether to perform a fault repair operation based on the fault level. The fault repair operation involves a backup string inverter replacing the failed string inverter and operating in the branch corresponding to the failed string inverter.

[0011] Furthermore, the specific steps for communication and networking between the various string inverters within the photovoltaic power station system are as follows: The cloud platform receives device data from all string inverters in the photovoltaic power station system, divides the local area network by device installation identifiers, and generates network configuration information. The device data includes one or more of the following: device ID, signal strength, installation identifier, default number of networks, maximum number of networks in the local area network, and minimum number of devices in the local area network. The cloud platform broadcasts the network configuration information to all string inverter devices in the local area network. When a device receives the subscribed configuration information, it uploads the network information of signal strength and installation identification to the cloud platform. Based on the network information uploaded by each device, the cloud platform determines the master device according to the network strategy of signal strength first and installation identification second, and sends the local MESH network device range configuration file to the master device in the local area network. After the master device in each local area network is determined, the master device initiates a network connection request to the slave devices in the local area network. Based on the connection request from the master device, the slave devices compare the signal strength in the slave device ring network according to the order of device installation identifiers. After the signal comparison, the device with the strongest signal in the slave device network is determined as the backup master device, and the network configuration information in the device is updated.

[0012] Furthermore, when the faulty device is a slave device, the specific steps for determining the location of the faulty string inverter in the power grid are as follows: When a slave device does not receive a heartbeat message from a faulty device, it reports the operating status, fault type, and installation identifier of the slave device in the ring network to the master device through a star network. The master device initiates a status query to the faulty device through the star network based on the installation identifier of the faulty device. After determining the operating status and fault type of the faulty device, the master device decides whether to perform fault repair operations based on the fault level determined by the faulty device.

[0013] Furthermore, when the faulty device is the master device, the specific steps for renetworking are as follows: When the primary device fails and the backup primary device detects the loss of the primary device's heartbeat message, the backup primary device initiates a network reconfiguration request. The slave devices in the other ring link sequentially determine the status of the primary device according to the size of the installation identifier. When all devices confirm the primary device failure, the backup primary device begins network reconfiguration and sets the original primary device to standby status.

[0014] Furthermore, the specific steps for troubleshooting are as follows: After confirming the location of the faulty equipment, the main equipment sends a faulty equipment information request to the cloud platform. When the equipment information and fault information on the cloud platform are consistent with the judgment result determined by the main equipment, the main equipment sends an installation identification request message with the faulty equipment to the standby string inverter. The standby string inverter queries the electrical configuration parameter table through the installation identification to determine the location of the external relay. After determining the electrical wiring location, the standby string inverter sends an execution request to the main equipment. After receiving the execution request, the main equipment issues an execution command. Before execution, the standby string inverter performs multiple reclosing operations and collects the AC side voltage to determine the AC side voltage value. When it is confirmed that the faulty equipment has exited the operating state, the standby string inverter engages the corresponding relay and completes the grid connection operation, and returns the execution result.

[0015] Compared with the prior art, the advantages of the present invention are as follows: This invention achieves a high degree of coordination between the generation side, grid connection side, and monitoring side through the collaboration of photovoltaic module arrays, string inverter units, grid-connected cabinets, communication cabinets, and cloud platforms. Each string is independently configured with DC and AC switching devices, improving system safety and maintenance convenience. The grid-connected cabinet centrally collects and protects the inverter output, ensuring stable and reliable grid-connected operation. The communication cabinet centrally collects and uploads data, enabling the cloud platform to achieve remote monitoring and intelligent management, thereby significantly improving the reliability, maintainability, and operating efficiency of photovoltaic power plants.

[0016] This invention enables the sharing of status information of equipment within a power plant through self-organizing network communication between string inverters. The master-slave device mechanism combined with cloud platform monitoring can accurately locate and repair faults. Backup inverters are in standby mode in advance and can be quickly put into operation to replace faults, improving the continuity and power generation stability of the system. At the same time, the network can be automatically reorganized after the master equipment fails, significantly improving the reliability and fault tolerance of the power plant. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the internal equipment structure of a residential new energy distributed photovoltaic power station system in a specific application embodiment.

[0018] Figure 2 This is a diagram of the local area network communication topology for equipment within a power plant, as shown in a specific application example.

[0019] Figure 3 This is a flowchart of the main device determination and initial network setup in a specific application embodiment.

[0020] Figure 4 This is a flowchart for locating the faulty device in a specific application embodiment.

[0021] Figure 5 This is a flowchart illustrating the re-networking process when the main device fails, as shown in a specific application example.

[0022] Figure 6 This is a flowchart illustrating the fault commissioning and accidental switching of backup equipment in a specific application embodiment. Detailed Implementation

[0023] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0024] Example 1 like Figure 1 As shown, the residential renewable energy distributed photovoltaic power station system of this embodiment includes: Photovoltaic module arrays, string inverter units, grid-connected cabinets, communication cabinets, cloud platforms, and power grids; The photovoltaic module array includes a number of photovoltaic modules, wherein the DC output terminal of each photovoltaic module is connected to the DC input terminal of the corresponding string inverter via a corresponding DC side electrical switching device; The string inverter unit includes multiple string inverters for converting DC input to AC output. The AC output terminal of each string inverter is connected to the grid-connected cabinet via an AC side electrical switching device. The grid-connected cabinet is connected to the power grid via an AC line. Each string inverter is also connected to a communication cabinet via a communication line. The communication cabinet is used to collect, manage, and upload the operating data of the string inverters. The communication cabinet interacts with the cloud platform via the communication line.

[0025] In this embodiment, the string inverter unit further includes a backup string inverter. The DC input terminal of the backup string inverter is connected to the DC output terminal of each photovoltaic module through multiple DC-side switches, and the AC output terminal is connected to the AC output terminal of each string inverter through multiple AC-side switches. The backup string inverter is used to put into operation when the string inverter fails.

[0026] In this embodiment, a DC-side electrical switching device is provided before the DC input terminal of the backup string inverter, and an AC-side electrical switching device is provided after the AC output terminal of the backup string inverter.

[0027] In this embodiment, each string inverter transmits data to the communication cabinet via an RS485 communication line or wireless communication, and the communication cabinet transmits data to the cloud platform via optical fiber or wireless communication.

[0028] In this embodiment, the string inverters communicate and network with each other through Mesh technology. Based on the installation location and communication signal strength of each string inverter, the string inverters in the power station are divided into one or more local area networks. Each local area network includes a master device responsible for external communication and several slave devices. The communication topology logic in the local area network adopts a combination of ring topology and star topology for wireless transmission and fault location of devices within the local area network.

[0029] In specific application embodiments, due to the dispersed installation of distributed devices and the distance between them, when using Mesh technology for communication networking, the devices in the power station can be divided into one or more local area networks (LANs) based on factors such as the installation location of inverters and the strength of communication signals. Each LAN has a master device responsible for external communication. Within the LAN, the communication topology logic adopts a combination of ring and star topologies for wireless transmission and fault location of devices within the LAN.

[0030] When a power plant has only one local area network (LAN), during normal grid operation, equipment operating data is collected within the LAN using a combination of ring and star topologies to monitor device status. The master device collects all equipment information in a time-division manner via heartbeat messages and uploads it to the information management platform. Slave devices transmit fault status data, heartbeat flags, and ring network operating status data wirelessly to designated recipients at regular intervals, thus forming a unidirectional fault information communication loop within the communication network (e.g., ...). Figure 2 (As shown).

[0031] When there are multiple local area networks (LANs) within the power station, the main equipment of each LAN communicates directly with the cloud platform and communication cabinet.

[0032] During normal operation of the power plant, slave devices within each local area network (LAN) are responsible for exchanging fault information, while the master device is responsible for isolating faults within the LAN. When a major fault occurs, the slave devices within the LAN actively initiate fault data exchange within the ring network they form.

[0033] When a faulty device is detected in the network, the main device of the network where the faulty machine is located initiates a self-healing request to operate redundant devices; when multiple faulty devices are detected in the network, the main device of the network where the faulty machine is located initiates a self-healing request to the power plant cloud platform to operate redundant devices according to the priority level of the fault type. When multiple faults are detected in the network and the faulty machines are not in the same local area network, the master devices of each local area network actively exchange fault information to determine the fault type and fault priority, and then initiate a self-healing request to operate the redundant device (i.e., the backup string inverter) according to the configuration policy (fault priority policy / device repair priority policy).

[0034] Example 2 This embodiment provides a fault repair method for a household renewable energy distributed photovoltaic power station system based on Embodiment 1, including the following steps: When the power station is running, the inverters in each string within the photovoltaic power station system communicate and form a network. Within the communication network, each inverter in each string is initialized according to the communication configuration file issued by the cloud platform when it first starts running. When the power station is running, the electrical switching devices controlling the DC and AC sides of each string inverter are in the closed state, and the DC side switches of the standby string inverter are in the closed state and the AC side switches are in the open state, so that the standby string inverter works in the standby state. The cloud platform monitors the operating status of each string inverter in real time based on the operating status data periodically reported by the master device in the local area network composed of each string inverter. If a string inverter is detected to have failed and the failed device is a slave device, the platform determines the location of the failed device in the power grid and decides whether to perform a fault repair operation based on the fault level. If the failed device is a master device, the platform re-networks the inverter and decides whether to perform a fault repair operation based on the fault level. The fault repair operation involves a backup string inverter replacing the failed string inverter and operating in the branch corresponding to the failed string inverter.

[0035] In a specific application embodiment, to ensure the reliable operation of the entire system, this embodiment adopts the method of equipment redundancy to eliminate faulty equipment and put into operation backup equipment in the photovoltaic power station, thereby ensuring the reliable operation of the entire system.

[0036] During normal operation of the power station, the inverter equipment within the photovoltaic power station uses Bluetooth wireless mesh technology for communication and networking. Within the communication network, upon initial startup, each device determines its communication targets and message content based on a communication configuration file sent from the cloud. Devices determine their recipients, information content, and communication range by subscribing to device identifiers that match their characteristic values. The recipients and published content are confirmed by adding a publishing identifier to the messages sent by the devices.

[0037] During normal operation of the power plant, the electrical switching devices (KTn, ACn) on the DC and AC sides of the inverter are in the closed state. This is controlled by the inverter relays. The DC side line switch (Kn) of the redundant equipment (i.e., the standby string inverter) is in the closed state, and the AC side switch (Kacn) is in the open state, with the redundant equipment operating in standby mode.

[0038] When a major inverter failure occurs, the inverter equipment will be in a shutdown or offline state, and the switching device ACn will be in an open state. First, the faulty device will determine the fault type and fault code based on its own protection functions. The photovoltaic operation and maintenance cloud platform will determine whether the device is running or operating in a fault state based on the operating status reported by the device. In the local communication network, the master device determines the fault type of the faulty device based on the heartbeat message loss alarm and the fault code in the heartbeat message. The slave device determines the location information of the faulty device in the grid based on the lost device SN number in the heartbeat message. Once the location of the faulty device is located, the line switching module in the backup inverter will detect whether the AC side switch of the faulty device is open. Based on the previously determined location information of the faulty device, the master device in the communication system connects the electrical switch of the backup device to the electrical line of the faulty device, and the AC side switch Kacn is put into operation in the faulty branch. This realizes the function of the backup device being put into operation, ensuring the stability of the entire power plant's operating power.

[0039] This embodiment addresses the issue of photovoltaic power plants being unable to operate at full power due to equipment failures, thus saving customers some maintenance costs. Wireless Bluetooth communication enables networking between devices and communication between devices and data acquisition systems. Software configuration enhances the flexibility of the communication topology while reducing construction workload. Localized automatic control of the devices is achieved through information exchange between renewable inverters and between inverters and data acquisition devices (e.g., communication cabinets and cloud platforms). When a major equipment failure occurs within the power plant, the power generation network removes the faulty equipment, enabling self-healing operation of the power generation system. This approach can be widely applied to distributed renewable residential photovoltaic power plants and renewable microgrid systems, especially suitable for low-power residential products (10kW~125kW), such as micro photovoltaic power plants and microgrid systems.

[0040] In this embodiment, during the initial operation of the power grid, the equipment in the power station responds to the networking request from the cloud platform, and performs network partitioning and updates network configuration information through the cloud platform, such as... Figure 3 As shown, the specific steps for communication and networking between the various string inverters within a photovoltaic power station system are as follows: First, the cloud platform receives device data from all string inverters in the photovoltaic power station system, divides the local area network by device installation identifier (SN code) and generates network configuration information. The device data includes one or more of the following: device ID, signal strength, installation identifier, default number of networks, maximum number of networks in the local area network, and minimum number of devices in the local area network. Secondly, the cloud platform broadcasts the network configuration information to all string inverter devices in the local area network. When the device receives the subscribed configuration information, it uploads the network information such as signal strength and installation identification to the cloud platform. Based on the network information uploaded by each device, the cloud platform determines the master device according to the network strategy of prioritizing signal strength and then installation identification, and sends the local MESH network device range configuration file to the master device in the local area network. After the master device in each local area network is determined, the master device actively initiates a network connection request to the slave devices in the local area network. Based on the connection request from the master device, the slave devices compare the signal strength in the slave device ring network according to the device installation identifier SN number. After the signal comparison, the device with the strongest signal in the slave device network is determined as the backup master device, and the network configuration information in the device is updated.

[0041] The network can be structured using Bluetooth Mesh, a wireless communication network topology based on Bluetooth technology. It allows multiple Bluetooth devices to communicate and collaborate, forming a large-scale multi-point to multi-point network. Each Bluetooth device in the Mesh network is called a node and can send, receive, or forward messages. Some nodes can also be configured as relay nodes to forward messages to other nodes, thus covering a larger physical area. Optionally, Wi-Fi Mesh technology can be used instead. For communication within the power plant, the MESH networking format employs two methods. Communication information uses hierarchical grouping: master and slave devices exchange operational data, and peer devices exchange device status. Alternatively, various devices within the power grid can be localized according to their type, enabling networking within the local area network and self-healing for faults in devices of the same type.

[0042] In this embodiment, when the faulty device is a slave device, the specific steps for determining the location of the faulty string inverter in the power grid are as follows: When a slave device does not receive a heartbeat message from a faulty device, it reports the operating status, fault type, and installation identifier of the slave device in the ring network to the master device through a star network. The master device initiates a status query to the faulty device through the star network based on the installation identifier of the faulty device. After determining the operating status and fault type of the faulty device, the master device decides whether to perform fault repair operations based on the fault level determined by the faulty device.

[0043] In specific application embodiments, such as Figure 4 As shown, when a faulty device exists in the system, it is either stopped or offline. If the faulty device is a slave device, it will stop sending heartbeat messages to the publishing object. Figure 2The ring topology will be interrupted. Slave devices that do not receive heartbeat messages will proactively report their operating status, fault type, and location (SN number) within the ring network to the master device via a star network. The master device, based on the faulty device's installation location information (SN number), then initiates a status query to the faulty device via the star network. After confirming that the faulty device's operating status, fault type, and SN code match the slave device, the master device decides whether to perform self-healing based on the fault level determined by the device (fault self-healing is a technical system that uses real-time alarm detection, pre-diagnosis analysis, automatic fault recovery, and forms a closed loop). When self-healing is required, the master device issues the faulty device's SN identifier to the backup device. The backup device, based on the identifier, determines the wiring location using its internal electrical configuration table.

[0044] In this embodiment, as Figure 5 As shown, when the faulty device is the master device, the specific steps for renetworking are as follows: When the primary device fails and the backup primary device detects the loss of the primary device's heartbeat message, the backup primary device initiates a network reconfiguration request. The slave devices in the other ring links sequentially determine the status of the primary device according to the size of the installation identifier SN. When all devices confirm the primary device failure, the backup primary device begins network reconfiguration and sets the original primary device to standby status.

[0045] In this embodiment, when a major equipment failure occurs, the equipment is in a shutdown or offline state. At this time, the grid-connected ACn is in a disconnected state. To achieve fault switching, as follows... Figure 6 As shown, the specific steps for troubleshooting are as follows: After confirming the location of the faulty equipment, the master equipment initiates a faulty equipment information request to the cloud platform. When the equipment information and fault information on the cloud platform are consistent with the judgment result determined by the master equipment, the master equipment sends an installation identifier (SN) request message containing the faulty equipment's SN to the standby string inverter. The standby string inverter queries the electrical configuration parameter table through the installation identifier to determine the location of its external relay. After determining the electrical wiring location, the standby string inverter sends an execution request to the master equipment. Upon receiving the execution request, the master equipment issues an execution command. Before execution, the standby string inverter performs multiple reclosing operations and collects the AC side voltage to determine the AC side voltage value. When it is confirmed that the faulty equipment has exited the operating state, the standby string inverter engages the corresponding relay and completes the grid connection operation of the equipment, returning the execution result.

[0046] Compared with the prior art, the present invention has the following beneficial effects: In existing technologies, when equipment in a distributed power station malfunctions and becomes completely inoperable, repairs often require on-site visits from the manufacturer's after-sales personnel. During this waiting period, the equipment at that node must be shut down, impacting the overall efficiency of the power station. Normal operation can only be guaranteed after the after-sales personnel repair the fault. This invention enables fault monitoring between devices within the power station by transmitting operational data via Bluetooth. When a device malfunctions and is confirmed to be unrecoverable, the master device in the mesh network first uses a software algorithm to locate the faulty device. Then, the faulty device is removed from the power generation network. Finally, redundant inverters are put into operation on the power grid. Through these operations, self-healing of faulty nodes within the new energy power station is achieved. When equipment malfunctions within a distributed power station, software algorithms and actuators effectively prevent partial equipment malfunctions, significantly improving the stability of the power station and avoiding economic losses for the owner.

[0047] For communication between devices in distributed power plants, most current solutions use wired cables. The communication topology of the entire system is determined by the wired communication electrical design, leading to complex equipment installation, a high risk of errors, and insufficient flexibility in subsequent communication topology expansion. This invention employs Bluetooth Mesh technology to achieve wireless Bluetooth networking between devices. Communication between devices and data acquisition systems is automatically configured through communication algorithms and software, improving the flexibility of the communication topology and reducing construction workload. After the power plant is put into operation, the communication topology is determined by the configuration software and can be remotely upgraded. This significantly reduces the difficulty and workload of subsequent power plant upgrades and modifications.

[0048] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A residential distributed photovoltaic power station system, characterized in that, include: Photovoltaic module arrays, string inverter units, grid-connected cabinets, communication cabinets, cloud platforms, and power grids; The photovoltaic module array includes a number of photovoltaic modules, wherein the DC output terminal of each photovoltaic module is connected to the DC input terminal of the corresponding string inverter via a corresponding DC side electrical switching device; The string inverter unit includes multiple string inverters for converting DC input to AC output. The AC output terminal of each string inverter is connected to the grid-connected cabinet via an AC side electrical switching device. The grid-connected cabinet is connected to the power grid via an AC line. Each string inverter is also connected to a communication cabinet via a communication line. The communication cabinet is used to collect, manage, and upload the operating data of the string inverters. The communication cabinet interacts with the cloud platform via the communication line.

2. The household renewable energy distributed photovoltaic power station system according to claim 1, characterized in that, The string inverter unit also includes a backup string inverter. The DC input terminal of the backup string inverter is connected to the DC output terminal of each photovoltaic module through multiple DC-side switches, and the AC output terminal is connected to the AC output terminal of each string inverter through multiple AC-side switches. The backup string inverter is used to put into operation when the string inverter fails.

3. The household new energy distributed photovoltaic power station system according to claim 2, characterized in that, The standby string inverter is provided with a DC side electrical switching device before the DC input terminal and an AC side electrical switching device after the AC output terminal.

4. The household renewable energy distributed photovoltaic power station system according to any one of claims 1-3, characterized in that, Each string inverter communicates with the communication cabinet via RS485 communication lines or wireless communication, and the communication cabinet communicates with the cloud platform via optical fiber or wireless communication.

5. The household renewable energy distributed photovoltaic power station system according to any one of claims 1-3, characterized in that, Each string inverter communicates and networks with each other using Mesh technology. Based on the installation location and communication signal strength of each string inverter, the string inverters in the power station are divided into one or more local area networks. Each local area network includes a master device responsible for external communication and several slave devices. The communication topology logic in the local area network adopts a combination of ring topology and star topology for wireless transmission and fault location of devices within the local area network.

6. A fault repair method for a household renewable energy distributed photovoltaic power station system according to any one of claims 1-5, characterized in that, Including the following steps: When the power station is running, the inverters in each string within the photovoltaic power station system communicate and form a network. Within the communication network, each inverter in each string is initialized according to the communication configuration file issued by the cloud platform when it first starts running. When the power station is running, the electrical switching devices controlling the DC and AC sides of each string inverter are in the closed state, and the DC side switches of the standby string inverter are in the closed state and the AC side switches are in the open state, so that the standby string inverter works in the standby state. The cloud platform monitors the working status of each string inverter in real time based on the operating status data periodically reported by the master device in the local area network composed of each string inverter. If a string inverter is found to have a fault and the faulty device is a slave device, the platform determines the location of the faulty device in the power grid and decides whether to perform fault repair operation based on the fault level. If the faulty device is the primary device, then a re-networking process is performed, and a fault repair operation is performed based on the fault level. The fault repair operation involves a backup string inverter replacing the faulty string inverter in the branch corresponding to the faulty string inverter.

7. The fault repair method according to claim 6, characterized in that, The specific steps for communication and networking between the various string inverters within a photovoltaic power station system are as follows: The cloud platform receives device data from all string inverters in the photovoltaic power station system, divides the local area network by device installation identifiers, and generates network configuration information. The device data includes one or more of the following: device ID, signal strength, installation identifier, default number of networks, maximum number of networks in the local area network, and minimum number of devices in the local area network. The cloud platform broadcasts the network configuration information to all string inverter devices in the local area network. When a device receives the subscribed configuration information, it uploads the network information of signal strength and installation identification to the cloud platform. Based on the network information uploaded by each device, the cloud platform determines the master device according to the network strategy of signal strength first and installation identification second, and sends the local MESH network device range configuration file to the master device in the local area network. After the master device in each local area network is determined, the master device initiates a network connection request to the slave devices in the local area network. Based on the connection request from the master device, the slave devices compare the signal strength in the slave device ring network according to the order of device installation identifiers. After the signal comparison, the device with the strongest signal in the slave device network is determined as the backup master device, and the network configuration information in the device is updated.

8. The fault repair method according to claim 6, characterized in that, When the faulty device is a slave device, the specific steps to determine the location of the faulty string inverter in the power grid are as follows: When a slave device does not receive a heartbeat message from a faulty device, it reports the operating status, fault type, and installation identifier of the slave device in the ring network to the master device through a star network. The master device initiates a status query to the faulty device through the star network based on the installation identifier of the faulty device. After determining the operating status and fault type of the faulty device, the master device decides whether to perform fault repair operations based on the fault level determined by the faulty device.

9. The fault repair method according to claim 6, characterized in that, When the faulty device is the master device, the specific steps for reconfiguring the network are as follows: When the primary device fails and the backup primary device detects the loss of the primary device's heartbeat message, the backup primary device initiates a network reconfiguration request. The slave devices in the other ring link sequentially determine the status of the primary device according to the size of the installation identifier. When all devices confirm the primary device failure, the backup primary device begins network reconfiguration and sets the original primary device to standby status.

10. The fault repair method according to claim 6, characterized in that, The specific steps for troubleshooting are as follows: After confirming the location of the faulty equipment, the main equipment sends a faulty equipment information request to the cloud platform. When the equipment information and fault information on the cloud platform are consistent with the judgment result determined by the main equipment, the main equipment sends an installation identification request message with the faulty equipment to the standby string inverter. The standby string inverter queries the electrical configuration parameter table through the installation identification to determine the location of the external relay. After determining the electrical wiring location, the standby string inverter sends an execution request to the main equipment. After receiving the execution request, the main equipment issues an execution command. Before execution, the standby string inverter performs multiple reclosing operations and collects the AC side voltage to determine the AC side voltage value. When it is confirmed that the faulty equipment has exited the operating state, the standby string inverter engages the corresponding relay and completes the grid connection operation, and returns the execution result.

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