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CN-122029714-A - Net-structured output limiting control system and method

CN122029714ACN 122029714 ACN122029714 ACN 122029714ACN-122029714-A

Abstract

The invention relates to a photovoltaic power generation output limit control technology, in particular to a grid-structured output limit control system and method used with a photovoltaic inverter. According to the present invention, by combining the inertia control which cannot be achieved by the existing photovoltaic inverter with the grid-structured inverter, the inertia control can be performed more continuously, and the positive effects of being able to effectively manage and utilize the existing photovoltaic inverter apparatus can be obtained.

Inventors

  • JIANG ZHICHENG

Assignees

  • 韩国系统形成株式会社

Dates

Publication Date
20260512
Application Date
20231011

Claims (10)

  1. 1. A net-structured output limit control system, comprising: a photovoltaic inverter for converting direct current generated by the photovoltaic module into alternating current, and And the grid-formed inverter is connected with the photovoltaic inverter in parallel and is used for executing voltage source control on a power grid.
  2. 2. The system of claim 1, further comprising a DC communication device connecting the photovoltaic inverter and the grid-tied inverter, The dc communication device operates as follows: In the case that the dc voltage of the grid-formed inverter is higher than the dc voltage of the photovoltaic inverter, the switch is opened so that the photovoltaic inverter is not connected to the grid-formed inverter; And when the direct current voltage of the grid-formed inverter is lower than the direct current voltage of the photovoltaic inverter, the switch is conducted, so that the photovoltaic inverter is connected with the grid-formed inverter.
  3. 3. The system of claim 1, further comprising an energy storage device connected to the grid-tied inverter through which stored energy is released when a disturbance occurs to the grid.
  4. 4. The system of claim 1, wherein the grid-tied inverter comprises: A grid-formed communication part for receiving grid-off signals of a photovoltaic inverter power system or output limit instructions of photovoltaic power generation caused by grid disturbance, and And the network construction control part is used for executing corresponding control when receiving the power system off-grid signal or the output limiting command.
  5. 5. The system according to claim 4, wherein the grid-formation control unit controls the output of the photovoltaic module at a preset dc voltage set point by performing dc communication with the photovoltaic module when receiving the off-grid signal of the photovoltaic inverter power system due to the grid disturbance.
  6. 6. The system according to claim 4, wherein the grid-formation control unit controls the output of the photovoltaic module at a point deviated from the maximum power point of the photovoltaic module by performing dc communication with the photovoltaic inverter when receiving an output limit command of the photovoltaic power station from the outside.
  7. 7. The system according to claim 4, wherein the grid formation control unit, when receiving an emergency output limit command from the outside or when determining that output limit is required for system stability, causes the photovoltaic inverter to be off-grid by increasing an ac output voltage of the power grid.
  8. 8. A mesh type output limit control method executed in a mesh type output limit control system including a photovoltaic inverter and a mesh type inverter connected in parallel with the photovoltaic inverter and performing voltage source control on a power grid, characterized by comprising: the grid-structured inverter receives off-grid signals of a photovoltaic inverter power system or output limit instructions of photovoltaic power generation caused by grid disturbance, and And executing corresponding control under the condition that the off-grid signal or the output limiting command is received.
  9. 9. The method as recited in claim 8, further comprising: A step of switching on a switch in a case where a DC voltage of the grid-formed inverter is lower than a DC voltage of the photovoltaic inverter by a DC communication device connecting the photovoltaic inverter and the grid-formed inverter so that the photovoltaic inverter is connected to the grid-formed inverter, and And the grid-formed inverter is in direct current communication with the photovoltaic power station, and the power output of the photovoltaic power station is controlled at a preset direct current voltage set point.
  10. 10. The method as recited in claim 8, further comprising: and under the condition that an output limiting instruction of photovoltaic power generation is received, the grid-structured inverter enables the photovoltaic inverter to be off-grid by improving the alternating current output voltage of the power grid.

Description

Net-structured output limiting control system and method Technical Field The present invention relates to a power limiting control technology for solar power generation, and more particularly, to a grid-structured power limiting control system and method coupled to a solar inverter. Background With the advancement of global carbon emission reduction policies, renewable energy power generation is continuously increased, and thermal power stations are continuously reduced. However, with the increase of inverter-type power generation facilities to which power electronics technology for converting renewable energy is applied, a Weak Grid problem (wea Grid is) occurs in which the Grid voltage and frequency maintenance capability is reduced. Furthermore, as renewable energy sources increase, the robustness of the grid system is decreasing. On the other hand, when the photovoltaic power plant receives the output limit instruction, it is possible to cope with the manner of storing the produced energy in the battery, reducing the output operation, or stopping the power plant operation. However, first, the method of storing energy in the battery is only feasible when the battery is mounted, and is not suitable as a method of coping with the output limitation command for the existing power station without the battery. Second, the reduced output operation mode can be implemented only on intelligent inverters in current source controlled inverters, and most photovoltaic inverters currently installed do not have the function of operating in this mode. Third, shutdown of the plant is the only option in reality, but the photovoltaic energy cannot be sold during shutdown, which can lead to direct economic loss to the photovoltaic plant owners. In the environment of increasing renewable energy sources, existing photovoltaic power plants have heretofore been difficult to handle due to stability problems, except when they are taken off the grid or are subject to output limiting measures to stop operation. The background of the present invention is disclosed in korean registered patent No. 10-2320750. Disclosure of Invention Technical problem The invention aims to provide a grid-structured output limit control system and a grid-structured output limit control method, which can continuously output photovoltaic power generation when a power grid is disturbed and provide limited power output when the output is limited. The technical problems to be solved by the present invention are not limited to the above technical problems, and other technical problems not mentioned are apparent to those of ordinary skill in the art to which the present invention pertains from the following description. Solution scheme According to one aspect of the present invention, a web-formed output limit control system is provided. A grid-formed output limit control system according to an embodiment of the present invention includes a photovoltaic inverter for converting direct current generated by a photovoltaic power station into alternating current, and a grid-formed inverter connected in parallel with the photovoltaic inverter and performing voltage source control on a power grid. According to an embodiment of the present invention, the photovoltaic inverter further comprises a dc communication device for connecting the photovoltaic inverter and the grid-formed inverter, wherein the dc communication device is configured to switch off when the dc voltage of the grid-formed inverter is higher than the dc voltage of the photovoltaic inverter, so that the photovoltaic inverter is not connected to the grid-formed inverter, and to switch on when the dc voltage of the grid-formed inverter is lower than the dc voltage of the photovoltaic inverter, so that the photovoltaic inverter is connected to the grid-formed inverter. According to an embodiment of the invention, the energy storage device is connected to the grid-formed inverter and provides energy. According to another aspect of the present invention, there is provided a web-formed output limit control method and a computer program executing the method and having a computer-readable recording medium recorded thereon. The grid-structured output limit control method comprises the steps that the grid-structured inverter receives a grid-off signal or a photovoltaic power generation output limit instruction of a photovoltaic inverter power system caused by grid disturbance, and corresponding control is executed when the grid-off signal or the output limit instruction is received. According to one embodiment of the invention, the method can further comprise the step of connecting the photovoltaic inverter and the grid-formed inverter by the direct current communication device, when the direct current of the grid-formed inverter is lower than the direct current of the photovoltaic inverter, a switch is conducted, so that the photovoltaic inverter is connected with the grid-formed inverter, and the step of contro