Symmetrical drop-off low voltage ride through reactive power control method of photovoltaic power generation system

Abstract

The invention relates to a symmetrical drop-off low voltage ride through reactive power control method of a photovoltaic power generation system. A controller detects whether a grid connection point voltage drops off in real time, and if the voltage does not drop off to 90% of a nominal voltage, an active current reference value id* is taken from an outer voltage loop, and grid connection control when the voltage is normal is adopted; if the grid connection point voltage drops off below 90% of the nominal voltage, the outer voltage ring is disconnected, low-voltage ride through control is adopted, namely inner current loop control is adopted, definite reactive power is output to a power grid by the photovoltaic power generation system according to the drop-off amplitude, and recovery of the voltage of the power grid is facilitated; if it is detected that the voltage recovers, the active power of the photovoltaic power generation system recovers at 10% rated power / second, reactive power is gradually reduced to zero at the same time, and finally the grid connection control when the voltage is normal is adopted. According to the method, an outlet current of a photovoltaic grid-connected inverter is limited within an over-current protection action current, reactive power support is provided for the grid voltage to recover to the normal value, investment of reactive power equipment is saved, and resources are saved.

Description

technical field [0001] The invention relates to a technology for integrating a photovoltaic power generation system into a power grid, in particular to a reactive power control method for symmetrical drop low voltage ride-through of a photovoltaic power generation system. Background technique [0002] With the increasingly prominent environmental and energy issues, the development and utilization of renewable green energy is an effective measure to solve the current environmental degradation and energy shortage. Photovoltaic power generation, as an important way of green energy development and utilization, has attracted the attention of countries all over the world, and the proportion of photovoltaic installed capacity in my country is also increasing, especially the investment in large-scale photovoltaic power generation. As a large number of photovoltaic power generation systems are connected to the grid, the method of quickly cutting the photovoltaic power generation syst...

AI Technical Summary

Problems solved by technology

[0005] The present invention is aimed at the problem of self-wasting reactive power caused by connecting a reactive power compensation device to supplement reactive power demand when a symmetrical drop fault occurs in the grid voltage, and proposes a photovoltaic power generation system symmetrical drop low voltage ride-through reactive power control method. The control strategy that can realize low-voltage ride-through of the photovoltaic power generation system and output reactive power to the grid at the same time solves the problem of grid connection when the photovoltaic power generation system fails symmetrically and makes full use of solar energy resources, reducing the input of reactive power equipment.

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