A voltage unbalance compensation device and a zero-sequence current compensation method

Abstract

The present invention provides a voltage unbalance compensation device and a zero-sequence current compensation method. The voltage unbalance compensation device includes a Z-shaped transformer arranged on the load side of the distribution station area, at least one commutation switch and a terminal controller, wherein : The Z-type transformer and the at least one commutation switch are connected in parallel to the grid, each commutation switch is connected in series with a load, and the neutral line of each load is connected to the neutral point of the Z-type transformer; the terminal controller is connected to each commutation switch The phase switch communication connection is used to repeat the steps of obtaining the commutation judgment parameters according to the zero-sequence current of the Z-type transformer or the total load current of each phase on the grid side, and after obtaining the commutation judgment parameters each time, if the judgment is known If it is judged that the parameter is greater than the preset value, the commutation step is executed. The method is applied to the device described above. The voltage unbalance compensation device and the zero-sequence current compensation method provided by the embodiments of the present invention improve the service life of the commutation switch and reduce the risk of commutation 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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