The Research On Static Var Compensator For Unbalanced Load

With the rapid development of national economy, there are more and more industrial devices being used in industry, such ac arc furnaces and rolling mills. These loads, which have the electric characteristics of asymmetry or impact, bring so much power quality problems as low power factor, voltage fluctuation and flicker, three phase voltage and current unbalanced, and etc. These problems are serious threatens to electric equipments, moreover it will also threat to the order of power system. Static var compensator (SVC) can solve well these problems synthetically. So it has important meaning to design the SVC of rapid response and good stability.This thesis introduced performance characteristic of the ac arc furnaces, put forward the optimized designing method of SVC's circuit parameters. This method offer techno-support for designing the SVC after promulgation of new national standard.The performance of SVC is determined by the strategy of control system. According to the different compensatory objects, this paper took a project which based on symmetry components to compensate. When SVC is used as the system compensatory, it is mainly used to adjust the system voltage. Therefore, the balanced control strategy is adopted. When SVC is used as the load compensatory, it is mainly used to restrain the voltage fluctuation and flash during the running of the impactive loads,so the unbalanced control strategy is adopted. According to this project, the hardware and software for the control system of SVC are designed. The data processing method and the strategy of the control system are also analyzed in detail.The optimized designing method of SVC's circuit parameters and the strategy of control system are validated by the SVC simulation. A small-scale experiment system is established, the results indicated that the system and its controller can timely compensate for unbalanced loads and reactive power, and received the expectation purpose.