Hybrid Power Quality Conditioner Installed in a Traction Substation by Optimized DC-Link Voltage

With the growth of railway electrification, power quality has played a major role in the designing of the system. Since electric trains are usually single-phase loads (except for some old three-phase trains), they draw high amounts of negative sequence component of currents. Furthermore, due to many reasons (e.g., the power-electronic switching converters at traction drives, pantograph/catenary interaction, arcs at section isolators, etc.), electric railway suffers from harmonic and transient currents. Therefore, many compensation methods were examined to maintain the power quality at an acceptable level. The Railway static Power Conditioner (RPC) can be an ideal compensator for high-speed railway, which contains two single phase back to back converters connected in parallel with traction substation through two step-down single-phase transformers. The operation of RPC is highly influenced by the DC-link voltage, which should maintained constant, usually by a PI-controller. In this paper, a Hybrid Power Quality Conditioner (HPQC) comprised of a RPC and a single phase SVC is presented to reduce the rating and total price of power electronic converters utilized in the compensator. A Genetic-Algorithm (GA) optimization is hired to tune accurately the DC-link controller coefficients. The simulation studies performed in MATLAB/Simulink revealed that the DC-link voltage ripple is reduced effectively, which results in a better performance and/or capacitor size decreasing

کلیدواژه ها:

Railway electrification ، Railway Static Power Conditioner (RPC) ، power quality ، static VAr compensator (SVC) ، GA-optimization ، Hybrid Power Quality Conditioner (HPQC)