Voltage imbalance compensation device and zero-sequence current compensation method

Abstract

The invention provides a voltage imbalance compensation device and a zero-sequence current compensation method. The voltage imbalance compensation device comprises a Z-type transformer, at least one phase change switch and a terminal controller which are arranged at the load side of a power distribution area, wherein the Z-type transformer and the at least one phase change switch are connected toa power grid in parallel, each phase change switch is connected with a load in series, and a zero line of each load is connected with a neutral point of the Z-type transformer; and the terminal controller is in communication connection with each phase change switch and is used for repeating the step of obtaining a phase change judgment parameter according to the zero sequence current of the Z-typetransformer or the total load current of each phase on the power grid side and executing the phase change step if the phase change judgment parameter is judged to be greater than a preset value afterthe phase change judgment parameter is obtained every time. The method is applied to the device. The voltage imbalance compensation device and the zero sequence current compensation method provided by the embodiment of the invention improve the service life of the phase change switch and reduce the risk of phase change failure.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a voltage unbalance compensation device and a zero-sequence current compensation method. Background technique [0002] As the most widely used form of energy today, electricity is a prerequisite for the development of various industries. With the development of various high-tech industries and the advancement of power reform, the power supply must not only keep up with the growing demand for power capacity, but also be able to Meet the increasingly high power quality requirements. [0003] At present, power quality problems are mainly reflected in reactive power compensation, harmonic control and three-phase imbalance. Most of the users are at the end of the distribution network, and most of them are single-phase loads. Since the three-phase loads change randomly and are usually unbalanced, three-phase unbalanced currents are generated, resulting in unbalanced three-ph...

AI Technical Summary

Problems solved by technology

However, the zero-sequence current compensation capability of the commutation switch is greatly affected by the load. As long as the three-phase load is unbalanced, the zero-sequence current will exist. At the same time, there are risks such as commutation failure and intermittent power failure during the commutation process; Z-type transformers The compensated zero-sequence current depends on the magnitude of the zero-sequence current of the load. When the zero-sequence current of the load is too large, it is easy to cause overcurrent or even damage to the Z-type transformer

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