The Research For Restraining Current Harmonics In Metro System By SVC

With the rapid development of national economics and electricity markets, power quality issues have captured considerable attention from both utility companies and their customers in many countries. More and more impactive loads, asymmetrical loads and nonelinear loads that bring a variety of disturbances in public network have been increasing into power system all the time, hence and the electric power quantity appeared increasingly worsen trend. A poor supply quality can degrade the quality of products, influence the work of many transportation and producing departments, so make a great deal of losses in economics. Therefore, along with the formation of the electricity market with push forward, the utility must not only meet the customer's requirements of increasing power quality, but also meet the requirement of excellent power quality.It needs the cooperation of the electricity utility and customers to manage power quality. One hand, the customers require power utility can insure them to use the normal electricity, on the other hand, power utility require their customers do not influence the normal operation of public network when they use electric power. Especially, it is necessary to manage power quality from headstream for some customers who need vast electric power and would cause the high worse of power quality of public network.See from national scope, metro system is one kind of big customers which can cause bad power pollution but there have no effective way to manage it. This status is caused by series of reasons. With the actualize of the tenth 5-years project, the numbers of metro transformer substations would be increased from 200 now to 300. The power pollution caused by metro system become worse. At present time, a large numbers of investigator pay attention to find the more effective and more oecumenical ways to manage the power pollution.In this paper, at first, the knowledge connected with power quality is introduced. And then, it is deeply understanded of the kinds and the harmonic characteristics of the electrical engine in our country, the primary way to supply electrical power in metro system, the fundamental and harmonic currents which would be infused from metro system to public network under the deferent ways of transformation of power. After deep understanding the researchful trends about harmonic restraining and based on our country's real status, a way of restraining harmonic by fitting SVC on both two arms of transformer (27.5kv) is put forward. In this paper, series of questions(the operational principle of SVC, the method to calculate the parameters of SVC, the control to TCR in SVC, an so on) will be expatiated and discussed. Finally, arm at a real metro system, on both two arms of tansformer two single-phase SVC are fitted. Based on Matlab, the tide models of fundaments and harmonics in metro system are built. And the SVC's real efficacies in harmonic restraining and dynamic reactive power compensation are validated.