Research On The Comprehensive Compensation Systerm For The Power Quality Of High-speed Electrified Railway

Due to high-speed railway itself complex power systems and electriclocomotives changing operating conditions result in power qualityproblems,such as serious harmonics, negative sequence and voltage fluctuations,which would seriously threaten the high-speed security and stability of railwaytraction network and traction power supply system, and will cause the country’sgreat economic losses with power accident. The high-speed railway plays animportant role in our social and economic development, therefore, should takeeffective measures to compensate and govern for high-speed railway powerquality.The high-speed rail system and AC-DC power supply electric locomotiveworks and features were introduced to determine that AC-DC EMU CRH2AT ismy research object,which CRH2is provided by power supply of V/v wiringmode under traction transformer.Then harmonics and negative sequence generation theory of high-speedrailway were analyzed in this paper. Three-level four-quadrant PWM rectifiers ofAC-DC train and harmonics of grid current were analyzed by Bilateral FourierTransform. Negative sequence current represented with the degree of unbalancecurrent, which the V/v traction transformer currents analyzed with symmetricalcomponents under different working conditions. The conclusion is that theharmonic and negative sequence current features of high-speed rail.In order to govern high-speed electrified railway harmonic and negativesequence current,this paper studied power quality comprehensive compensationsystem RPC-SVC compensation device by combining the railway powerregulator (Railway Static Power Conditioner, RPC) and static reactive power compensation device (Static Var Compensator, SVC).Analysed compensationprinciple of harmonic, negative sequence current and reactive power.Detectedcurrent instruction signal of the systerm based on the principle of phasediscrimination method and getted total instruction signal of RPC need tocompensate.Input this instruction signal to control unit and realized the control ofRPC by double-loop control of voltage loop and current loop. Finally,accordingto use Matlab/Simulink to verify the correctness of the method of detection andcontrol,while simulated three phase current of the systerm that aftercompensated.The results show that the effect of the compensation system hasgood harmonic suppression and negative sequence current governancefundamentally improve the high-speed rail power quality problems, to achieve acertain expectation.