Research On The Harmonic And Reactive Power Compensation In Traction Power Supply System

The electrified railway is the trend of railway transport development for its prominent advantages. But, the harmonic and reactive components produced by electrical locomotive not only caues added losses and reduce the utilization ratio of the traction transformer, but also influence the stability and security of electrical power system. So, harmonic control and reactive component compensation about traction power system attract lots of interests.This paper analyzed the harmonic and reactive components which exist in electrified railway in detail. The operational effects of the harmonic and reactive power compensation equipments which are used in Dongye traction power station Shuohuang railway, Zhoushizhuang and Gaoyang traction power station Fengshada railway are tested and analyzed in practical. The test results indicated that the harmonic and reactive power compensation equipments used in traction substation are passive. It emphasizes the compensation of reactive component and makes good effect, the average power factor can exceed 0.9 which is the international standard, and has certain effect in the harmonic control. But, when traction load is low, the capacitive reactive power returns to the power system. When harmonic traction load is high, the harmonic inject to power system will exceed the allowed standards, the maximum total harmonic voltage's distortion reach 6.99% which is 3.49 times of the national standards. The maximum current of third harmonic is 24.12A, which is 2.51 times of the national standards. The maximum current of fifthly harmonic is 14.95A, which is 1.56 times of the national standards.The active filter is a kind of new harmonic and reactive power compensation equipment. It can compensate reactive component as well as control harmonic. In this paper the fundamental of active filter and the traditional test method of harmonic and reactive-load current are introduced, the parallel compensation model and the control method of filter are analyzed. Based on the analyses of actual measure data, a model of Shunt Hybrid active power filter which is suitable for electrified railway is established, the control method and detection circuit is achieved. Theoretical analysis and simulation result indicate that the model can obtain satisfactory effect at the harmonic control and reactive power compensation.