Semi-adaptive harmonic control for power balancing device for AC traction

“RPC: Railway Static Power Conditioner” is a proven static voltage compensator system with a pair of single phase voltage source inverters in the feeding substation to avoid a voltage fluctuation of 3-phase power grid under an single phase AC electric railway load. Several substations for Shinkansen or conventional rail substations have RPCs until now. In Hokuriku Shinkansen section, there is another RPC with a function of harmonic compensation. There, in the case of emergency, length of the extended feeding circuit would exceed 100km. In such a case, stray capacitance between catenary and the earth would cause severe harmonic resonance. Thus RPC for this section introduce a semi-adaptive harmonic control algorithm to avoid a self-resonance. RPC watches active load current continuously and if load current is smaller than threshold level, RPC stops compensating harmonics. Also if compensating current for each harmonics order is too large, RPC stops the order. Authors have already conformed an appropriate operation for this semi-adaptive harmonic control algorithm with a simulation. RPC will test its ability in winter 2013 and will in service in spring 2015.