Reactive power compensation device and its control method based on modular multilevel topology

Abstract

A reactive power compensation device based on novel modular multilevel topology and a control method thereof relate to a high-voltage and large-power reactive power compensation device. In the prior art, compensation in a high-voltage and large-power field is limited and an inhibiting ability to circulation is insufficient. The invention aims at solving the above problems. A three-phase alternating-current power supply, a resistance-inductance load, a MMC converter, a signal detection circuit, a control circuit and a driving circuit are included. The MMC converter comprises three bridge arms which share a same structure and are connected in parallel. Each bridge arm comprises an upper bridge arm and a lower bridge arm which are symmetrical about a middle point of the bridge arm and are connected in series. Each upper bridge arm comprises a resistor, an inductor, several half-bridge units and an H bridge unit which are connected in series. The inductor of each upper bridge arm and an inductor of each lower bridge arm are connected in series. The middle points of the three bridge arms of the converter are connected in parallel between the three-phase alternating-current power supply and the load through a lead. By using the device and the method in the invention, power-grid reactive power can be compensated; a three-phase imbalance problem of a system is solved; effects of supporting a power grid voltage and inhibiting the circulation are achieved.

Description

technical field [0001] The invention relates to a reactive power compensation device and a control method thereof, in particular to a reactive power compensation device based on a modular multilevel converter and a control method thereof, and belongs to the technical field of high voltage and high power reactive power compensation. Background technique [0002] With the extensive application of power converters and nonlinear loads, a large number of reactive power and harmonics are generated in the power grid. The use of STATCOM for reactive power compensation and harmonic suppression can not only meet the requirements of power grid energy saving and loss reduction, but also help improve the quality of power grid power supply. [0003] Currently, there are three common multi-level topologies: diode-clamped, flying-capacitor, and H-bridge cascaded. Diode clamping type and flying capacitor type structure, as the number of levels increases, the number of switching devices and ...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to solve the problems of limited compensation and insufficient ability to suppress circulating current in the prior art in the field of high voltage and high power

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