Research On Static Var Compensator System For Impact Loads

With the rapid development of industry in China, more and more high capacity impact loads are applied in power systems, which gives rise to many serious problems in terms of power quality, such as voltage fluctuation, flicker and three-phase voltage imbalance. Thus, var compensation in power systems is of great importance to improving power system stability and reducing electrical power loss. Recently, along with the development of power electronics, Static Var Compensator (SVC) has become an alternative in a prior consideration in the var compensation of the impact loads, and is also one of the effective solutions to improving the power quality in China.Thus, SVC based on Thyristor Controlled Reactor (TCR) is designed in light of the electrical characteristics of high capacity impact loads in metallurgical industry. Meanwhile, SVC digital controlled system is developed based on the typical impact loads (such as electric arc furnace) and with the mean power compensating algorithm expressed in current and voltage of the instantaneous load. Furthermore, the whole package of SVC system (incl. digital thyristor trigger) and its hardware circuits have been developed, with DSP as the control chip and a singlechip as its peripheral circuits chip. Moreover, with the aid of C programming language, assembly language and VB.NET, the compensation algorithm, hardware circuit and monitoring system software are developed eventually. In addition, a simulation has been given to verify the feasibility of the system.Testing results show that newly developed TCR-based SVC and its digital control system have the following features:calculation of compensation algorithm is fast and accurate; the whole SVC system has favorable VAR compensation performance, quick response, high precision, good stability, easy debugging and powerful interaction between human and machine, etc. Comparing with the existing SVC, it is guaranteed that the new TCR-based SVC and its digital control system can be successfully applied in many industrial fields.