Research On Two Methods For Harmonic Elimination Of ChangAn LingMu Company's Distribution

At present, the capacity of nonlinear load such as arc furnaces used in the power systems and extended industrial enterprises increases far more rapidly, the harmonic pollution become a serious problem. And various electrical equipments and measuring instruments, which are complicated, sensitive to the electrical power quantity, become universal. Additionally the people's request to the electric power quantity and credibility is more and more high. To solve the problem, domestic and international scholars and electrical engineer are searching and studying the effective harmonic elimination measures in several decades.The traditional method is to use passive filter. This kind of method has the advantage of simple structure, low cost, maturing technique, stable running and high efficiency etc. But it also has weakness. It is susceptible to series and parallel resonance with the supply and the load. Its filtering characteristics are influenced by the supply impedance. Tuned passive filters are also susceptible to load and line switching transients and they are always off-tuned. The active power filter, a new method of filtering load harmonics, has been developed fast in the recent years. It can overcome the proper blemish of passive filter, but many technique problems under big capacity circumstance exist, the economic investment and running expenses are high, which affect its application and expansion. A hybrid active filter, which is a combination of an active filter in series with a shunt passive filter, has both the advantage of passive filter and active power filter.This paper is based on a real engineering. By analyzing the harmonic data measured in the welding workshop of Chongqing Changan Lingmu Automobile Limited Corporation, a set of low-voltage harmonic elimination apparatus has been designed and put into use. Further an active filter in series with a shunt passive filter is designed, simulation certificates the hybrid active power filter can improve the harmonic elimination results and raise the power factor.This paper pay great attention to the comparing between two kinds of harmonic elimination method for low-voltage network, and the evaluating function method is applied while comparing. Mathematical model including the economic costs and the harmonic suppress result is built up. Comparing results show that the passive filter still has a large applied space; Finally, the paper points out the scope of application for the two kinds of harmonic elimination methods, thus can give some reference to the electrical...