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In modern life, people require better power quality and more reliable power supply, effective reactive power compensation in power system is an important guarantee for the power grid to run safely, steady and economic. FACTS provides a new powerful tool to improve the operation functiona and economic benefits for the large and complex power system, among them, TCSC is one of the compensation technology which widely applied.Firstly, this paper introduced current research on the TCSC by some scholars, did a detailed analysis of its basic principles and working characteristics. Aim at the inherent flaws on TCSC, this paper improve on it, use the PWM technology to control the compensation circuit, in order to adjust the reactive power supply fast and efficiently.Based on the full reserve of the principle of traditional TCSC, this paper adopt high-frequency switch device substituted the ordinary Thyristor, used PWM control technology, designed a novel controllable circuit used for dynamic reactive power compensation, realize the fast, smooth adjustment of equivalent inductance in inductance circuit. This circuit not only inherited the excellent compensation characteristics, but also overcome the shortcomings of bring a large amount of harmonic and response lag in TCSC. Two full controlled switch devices reverse series compose the switch part, using the switch’s built-in anti-parallel diode, it makes the inductance circuit can high-frequency conduct in two directions. This compensation circuit is divided into three parts: main circuit, detection circuit and the control circuit, this paper gived the corresponding design scheme and specific realize method.In the end, the correctness and feasibility of this compensation circuit are proved through the MATLAB simulation platform. The simulation results shows that, the THD of steady-state current in circuit line is only 0.02%, when switching frequency is 10kHz, the process of dynamic response need almost 2~3 cycles, reflects fast and efficient performance that compensation circuit needed, with a good research value.
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