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CN-122000838-A - Off-grid control method and power equipment

CN122000838ACN 122000838 ACN122000838 ACN 122000838ACN-122000838-A

Abstract

The application provides a parallel-to-off network control method and power equipment. The parallel off-grid control method is applied to the main power equipment. The main power equipment is in communication connection with at least one auxiliary power equipment through a signal line and a protocol communication line, and each auxiliary power equipment and an alternating-current end of the main power equipment are connected with a power grid through corresponding grid-connected switches. The method comprises the steps of sending a power grid abnormality notification to the slave power equipment through a protocol communication line when grid-connected operation is conducted and power grid abnormality is confirmed, wherein the power grid abnormality notification is used for configuring the slave power equipment to output breaking signals through a signal line, the breaking signals are used for indicating all the power equipment to break grid-connected switches, controlling the grid-connected switches to break when the breaking signals are detected, controlling an alternating-current end to output off-grid alternating-current voltage, generating a synchronous signal according to an output phase angle of the off-grid alternating-current voltage and outputting the synchronous signal through the signal line, and the synchronous signal is used for indicating each slave power equipment to conduct off-grid phase synchronization. The control method provided by the application can reduce the damage probability of the grid-connected switch.

Inventors

  • Zhou Maoqiang
  • WANG LEI
  • CHEN XI

Assignees

  • 深圳市正浩创新科技股份有限公司

Dates

Publication Date
20260508
Application Date
20250612

Claims (10)

  1. 1. The parallel-to-off network control method is applied to a main power device, and is characterized in that the main power device is in communication connection with at least one auxiliary power device through a signal line and a protocol communication line, and an alternating-current end of each auxiliary power device and an alternating-current end of the main power device are respectively connected to a power grid through corresponding grid-connected switches, and the method comprises the following steps: When grid-connected operation is performed and the grid abnormality is confirmed, a grid abnormality notification is sent to the slave power equipment through the protocol communication line, the grid abnormality notification is used for configuring the slave power equipment to output a breaking signal through the signal line, and the breaking signal is configured to instruct all the power equipment to break the corresponding grid-connected switch; When the breaking signal is detected, the grid-connected switch corresponding to the main power equipment is controlled to be disconnected; after the grid-connected switch is disconnected, controlling an alternating-current end of the main power equipment to output off-grid alternating-current voltage; And generating a synchronizing signal according to the output phase angle of the off-grid alternating voltage and outputting the synchronizing signal through the signal line, wherein the effective edge of the synchronizing signal corresponds to a preset phase of the output phase angle, and the synchronizing signal is used for indicating each slave power equipment to perform off-grid phase synchronization.
  2. 2. The method for controlling off-grid according to claim 1, wherein after the grid-connected switch is turned off, before controlling the main power device to output the off-grid ac voltage, the method further comprises: and after the breaking signal is detected, a first preset time length is used for confirming that the grid-connected switch is disconnected.
  3. 3. The method for controlling off-grid according to claim 1, wherein before the controlling the ac terminal of the main power device to output the off-grid ac voltage, the method further comprises: and when the breaking signal is detected, controlling the alternating-current end of the main power equipment to stop outputting.
  4. 4. The off-grid control method of claim 1, further comprising: And after the power grid abnormality notification is sent, controlling the grid-connected switch to be disconnected for a second preset time period.
  5. 5. The grid-connected/disconnected control method according to claim 1, wherein before the transmission of the grid abnormality notification to the slave electric power device through the protocol communication line, the method further comprises: acquiring at least one of an actual grid voltage, an actual grid current and an actual grid power of the grid; Determining that the grid is abnormal when an abnormal condition is satisfied, wherein the abnormal condition includes at least one of: the actual grid voltage is less than the first grid voltage or the actual grid voltage is greater than the second grid voltage; The actual grid current is less than the first grid current or the actual grid current is greater than the second grid current; The actual power grid is smaller than the first power grid or larger than the second power grid; And receiving the power grid abnormality information reported by the power equipment.
  6. 6. The parallel-to-off network control method is applied to slave power equipment, and is characterized in that the slave power equipment is in communication connection with main power equipment through a signal line and a protocol communication line, and an alternating-current end of the slave power equipment and an alternating-current end of the main power equipment are respectively connected to a power grid through corresponding grid-connected switches, and the method comprises the following steps: outputting a breaking signal through the signal line when a power grid abnormality notification sent by the main power equipment is received through the protocol communication line, wherein the breaking signal is configured to instruct all the power equipment to break the corresponding grid-connected switch; When the breaking signal is detected, the grid-connected switch corresponding to the slave power equipment is controlled to be disconnected; After the grid-connected switch is disconnected, controlling the AC end of the slave power equipment to output off-grid AC voltage; And when the synchronous signal is detected through the signal line, carrying out off-grid phase synchronization according to the synchronous signal, wherein the effective edge of the synchronous signal corresponds to a preset phase of the output phase angle of the main power equipment.
  7. 7. The method of on-line and off-line control according to claim 6, wherein the outputting of the breaking signal through the signal line comprises: and continuously pulling the signal line high in a third preset time period.
  8. 8. The off-grid control method of claim 6, further comprising: And after receiving the power grid abnormality notification, controlling the grid-connected switch to be disconnected for a fourth preset time period.
  9. 9. The grid-connected/disconnected control method according to claim 6, wherein after the grid-connected switch is turned off, before the grid-connected/disconnected ac voltage is output from the ac terminal of the power device, the method further comprises: And when the breaking signal is detected through the signal line, controlling the alternating-current end of the slave power equipment to stop outputting.
  10. 10. An electrical device, characterized in that the electrical device comprises a memory and a processor for implementing the grid-connected and off-grid control method according to any one of claims 1 to 5 or the grid-connected and off-grid control method according to any one of claims 6 to 9 when executing a computer program stored in the memory.

Description

Off-grid control method and power equipment Technical Field The application relates to the technical field of power electronics, in particular to a parallel-off-grid control method and power equipment. Background With the increasing installation of distributed renewable energy sources and energy storage devices, structural changes are introduced to modern power distribution systems. The micro-grid based on the energy storage system can continuously supply power to regional loads without being separated from the power transmission system when the power grid fails, keeps off-grid operation, and exits the off-grid operation mode to be switched to a grid-connected operation mode when the power grid returns to normal. The energy storage device such as an energy storage converter (Power Conversion System, PCS) can be used for off-grid load operation, grid-connected rectification inversion, namely charging and discharging operation. When the grid-connected and off-grid operation is performed, a network side relay of the energy storage device has a scene of load breaking. If the network side relays of the plurality of energy storage devices are not disconnected synchronously, the network side relay which is disconnected finally can bear current exceeding the bearing capacity of hardware in a certain time, and further the network side relay is adhered and damaged. Disclosure of Invention In view of the above, the application provides a parallel-off-grid control method and a power device, which can better realize synchronous disconnection of grid-connected switches when a plurality of power devices are switched from grid connection to off-grid, thereby reducing the damage probability of the grid-connected switches and improving the safety of the power devices. The first aspect of the application provides a parallel-off-grid control method which is applied to main power equipment. The method comprises the steps that when grid connection operation is conducted and grid abnormality is confirmed, a grid abnormality notification is sent to the slave power equipment through the protocol communication line, the grid abnormality notification is used for configuring the slave power equipment to output breaking signals through the signal line, the breaking signals are configured to instruct all the slave power equipment to break the corresponding grid connection switches, when the breaking signals are detected, the grid connection switches corresponding to the master power equipment are controlled to break, after the grid connection switches are broken, the alternating current end of the master power equipment is controlled to output off-grid alternating current voltage, a synchronous signal is generated according to the output phase angle of the off-grid alternating current voltage and is output through the signal line, the effective edge of the synchronous signal corresponds to the preset phase of the output phase angle, and the synchronous signal is used for instructing each slave power equipment to conduct grid phase synchronization. In one embodiment, after the grid-connected switch is disconnected, before the main power equipment is controlled to output off-grid alternating voltage, the method further comprises the step of confirming that the grid-connected switch is disconnected after a breaking signal is detected for a first preset time length. In one embodiment, before the AC end of the main power equipment is controlled to output off-grid AC voltage, the method further comprises the step of controlling the AC end of the main power equipment to stop outputting when the breaking signal is detected. In one embodiment, the method further comprises controlling the grid-connected switch to be disconnected for a second preset time period after the power grid abnormality notification is sent. In an embodiment, before the notification of the grid abnormality to the slave power device through the protocol communication line, the method further comprises obtaining at least one of an actual grid voltage, an actual grid current and an actual grid power of the grid, determining the grid abnormality when an abnormality condition is met, wherein the abnormality condition comprises at least one of an actual grid voltage being smaller than the first grid voltage or an actual grid voltage being larger than the second grid voltage, an actual grid current being smaller than the first grid current or an actual grid current being larger than the second grid current, an actual grid power being smaller than the first grid power or an actual grid power being larger than the second grid power, and receiving grid abnormality information reported from the power device. The second aspect of the application provides a parallel-off-grid control method applied to slave power equipment. The method comprises the steps of outputting a breaking signal through a signal wire when a power grid abnormality notification sent by the main power equipment is re