Inverter reactive power control method based on virtual synchronization mechanism

Abstract

The invention discloses an inverter reactive power control method based on a virtual synchronization mechanism. At present, the inverter reactive power control method is not accurate in control. Whenthe grid voltage fluctuates slightly, the voltage cannot be controlled without any difference; when the grid voltage drops deeply, and the whole reactive power ability of the inverter cannot be played. The reactive power control method is divided into three phases: when it is monitored that the voltage of the grid-connected point is normal, a reactive power control module aims to control the output reactive power of the inverter; when the voltage drop of the grid-connected point is monitored, the reactive power control module superimposes the voltage of the grid-connected point to reduce the voltage drop; and when it is monitored that the voltage of the grid-connected point is further dropped, an LVRT control module controls the inverter to switch to a low voltage ride-through control modeto perform low voltage ride through. The invention can automatically and flexibly control the output reactive power of the inverter, improve the reactive power utilization rate of the inverter, stabilize the grid-connected point voltage, reduce the grid voltage drop degree, and does not affect the low voltage ride through capability of the inverter.

Description

technical field [0001] The invention relates to the control field of grid photovoltaic grid-connected inverters, in particular to an inverter reactive power control method based on a virtual synchronization mechanism. Background technique [0002] In recent years, a large number of photovoltaic grid-connected inverters have been connected to the grid, which has brought severe challenges to the operation and control of the grid. Synchronous generators in traditional grids have excellent inertia and damping characteristics, and can operate autonomously and participate in the regulation of grid voltage and frequency. In this context, researchers at home and abroad have proposed virtual synchronization technology, which simulates or partially simulates the frequency and voltage control characteristics of traditional synchronous generators from the external characteristics, and provides damping characteristics for the system, thereby improving the stability of distributed systems...

AI Technical Summary

Problems solved by technology

However, the control of this type of method is not precise. When the grid voltage fluctuates slightly, it cannot achieve voltage-free control; when the grid voltage drops deeply, it cannot exert its full reactive power.

The Chinese patent with the publication number CN105743130A discloses a method for improving the dynamic response performance of the reactive power of a virtual synchronous generator. This method does not consider the reactive power compensation strategy during low voltage ride-through

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