Continously variable series reactor: Impacts on distance protection using CCVTs

A continuously variable series reactor (CVSR) is a novel application of a well-known concept that provides continuous modulation of line reactance by controlling the magnetization in a ferromagnetic core. The target application is power flow control in meshed electric power systems. Modulation of the line impedance occurs by altering the bias of a dc winding to control the magnetization of the ferromagnetic core, thereby varying the reactance of the ac winding. Fault conditions can drive the CVSR outside of the control point in sub-cycle time and could affect distance protection along the controlled line. This study seeks to quantify such impacts using PSCAD™ simulations of a CVSR under fault conditions with CCVTs providing the line potential measurements. Impacts are observed through playback of the resulting waveforms into a distance relay. The results show that the interaction of the CVSR with CCVTs has minimal effect on distance protection reach.