Reactive power optimization and safety lifting device for photovoltaic inverter

Abstract

A photovoltaic inverter reactive power optimization and safety improvement device provided by the present invention comprises a composite protection circuit, a reactive power optimization circuit and an open circuit trigger circuit, the composite protection circuit is a resonant circuit, and the composite protection circuit is connected between a zero phase in an input end of the open circuit trigger circuit and a fire phase in an output end of the open circuit trigger circuit. The first end of the reactive power optimization circuit is connected to a power grid, the second end of the reactive power optimization circuit is connected with the input end of the open circuit trigger circuit, and the output end of the open circuit trigger circuit is connected with a photovoltaic inverter. According to the invention, by arranging the resonance circuit, island auxiliary protection is realized with extremely low cost, and the hidden danger of mis-tripping of the residual-current circuit breaker is avoided. Meanwhile, overvoltage protection and reactive power absorption during operation of the photovoltaic inverter are realized.

Description

technical field [0001] The invention belongs to the field of photovoltaic power generation auxiliary equipment, and in particular relates to a photovoltaic inverter reactive power optimization and safety lifting device. Background technique [0002] With the development of power electronics technology, more and more small-scale micro-grids with distributed power sources have been put into use. Among them, small-scale micro-grids represented by photovoltaic systems have unreliable island protection, reactive power disorder and easy overvoltage after a large number of small micro-grids are connected to the power grid. and other problems, and because the photovoltaic system contains a large number of electronic converters, its sensitivity to the disturbance of the power supply system also has special requirements for fault protection. If only relying on the protection of the electronic converter itself, sometimes there are significant limitations in islanding effect protection,...

AI Technical Summary

Problems solved by technology

If you only rely on the protection of the electronic converter itself, sometimes there will be significant limitations in islanding effect protection, overvoltage protection, etc.

[0003] In addition, after the photovoltaic system as a distributed power source is connected to the microgrid, due to the fluctuation of transmission power and the characteristics of distributed loads, the voltage at each load node of the microgrid transmission line is high or low, resulting in a voltage deviation exceeding the safe operation limit. Technical indicators, after large-scale distributed photovoltaics are connected, there is a problem of static voltage offset in local nodes of the distribution network

The distribution network, especially the low-voltage network, is sensitive to voltage changes. When the output of photovoltaic power generation peaks in the afternoon on a sunny day in early spring or autumn, the voltage of the low-voltage distribution network is often seriously high due to low load-side consumption, which affects power quality and power supply security. great challenge

At the same time, on the issue of relay protection, a large number of terminal distributed photovoltaics send fault currents back to the same level or the upper level grid. Since the existing distribution network protection does not consider the power direction, the probability of protection malfunction or refusal increases.

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