Variable inductor for voltage control in distribution networks

With an increasing penetration of distributed generation (DG) deviations in the distribution network voltage may occur as a consequence of changes, and even reversal, of the power flow in the feeders. In high voltage networks the voltage is normally controlled through reactive power that causes an in-phase voltage component across the reactance of the line. In distribution networks the feasibility of voltage control with reactive power is limited due to the low X/R ratio. A solution is proposed, which is based on the insertion of a controllable inductance in the feeder. In combination with reactive power support of the DG units the voltage can be controlled. The performance of the device is analysed and shown in several case studies