The evaluation of distance protection performance in the presence of Quadrature Boosters in support of a coordinated control strategy

This paper presents an assessment of the performance of distance protection for transmission lines in the presence of Quadrature Booster Transformers (QBs). The use of QBs in the UK transmission grid is increasing to maximise the utility of existing infrastructure as well as enabling rapid network modifications as dictated by operational requirements. An analysis is performed with the aid of a real time digital simulator (RTDS) to quantify the extent of error which may lead to the mal-operation of distance protection on transmission lines with QBs installed and operating under different scenarios. Using QBs in the future for more active constraint management may cause further complications that stretch existing protection schemes' capability. These issues are also considered. Furthermore the scope for an adaptive relaying solution is defined with focus on a wider scale coordination of protection for networks with QBs installed.