Method and system for controlling re-grid connection of photovoltaic grid-connected power generation system

Abstract

The invention discloses a method and a system for controlling re-grid-connection of a photovoltaic grid-connected power generation system, and belongs to the technical field of power system control. The method comprises the steps: when it is monitored that a photovoltaic power generation grid-connected switch is in an open state, keeping phase-locked loop control over a photovoltaic power generation grid-connected system, so that the voltage of the alternating current side of the inverter of the photovoltaic power generation grid-connected system and the voltage of a power grid are kept synchronous; inputting an impact suppression circuit into the direct current side of the inverter of the photovoltaic power generation grid-connected system, and controlling the impact suppression circuit to control the input and quit of an energy consumption resistor through a switching tube so as to suppress the voltage change of the direct current side of the inverter; and setting the d-axis currentcontrol reference value of the inverter of the photovoltaic power generation grid-connected system as the d-axis current control reference value before the photovoltaic power generation grid-connectedsystem is off-grid, and completing the re-grid connection of the photovoltaic grid-connected power generation system. According to the invention, the re-grid connection time of the photovoltaic powergeneration grid-connection system is reduced, the response speed of the photovoltaic power generation grid-connection system is accelerated, and the emergency control capability of photovoltaic to the power grid is exerted.

Description

technical field [0001] The present invention relates to the technical field of electric power system control, and more specifically, relates to a method and system for controlling reconnection of a photovoltaic grid-connected power generation system. Background technique [0002] In response to the energy crisis, renewable energy power generation has developed rapidly. Among them, photovoltaic grid-connected power generation technology is the focus of renewable energy power generation in recent years. As the proportion of photovoltaic power generation connected to the grid is getting higher and higher, the characteristics of power electronics in the power system are prominent, the system's rotational inertia is reduced, and the anti-disturbance and overload capabilities are continuously reduced. Grid disturbances and faults may cause large-scale power fluctuations, resulting in The collapse of system voltage and frequency depends on the control technology of power electroni...

AI Technical Summary

Problems solved by technology

Keeping photovoltaic off-grid without stopping, that is, keeping each component in a standby state, is the basis for flexible switching of photovoltaic and off-grid and rapid response to the grid. However, in the non-stop state, the photovoltaic array continues to output power, and the photovoltaic inverter The controllers of components such as DC / DC converters still work normally, while the inverter cannot transmit power to the grid. If the photovoltaics are directly connected to the grid, due to the delay in the response of the control system during the switching process of the operating mode, May generate large voltage and current impact during grid connection

[0006] At present, there is still little research on the control of photovoltaic re-connection to the grid. There is no control technology for reconnecting to the grid without stopping after photovoltaic off-grid. How to suppress the impact of photovoltaic re-connection process in the scenario of non-stop and short-term off-grid re-connection, to ensure the safety of photovoltaic equipment and the stability of the power system has become an urgent need for technical personnel in the field to solve question

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