Factors affecting the earth fault current in large-scale rural medium voltage cable network

This paper deals with the distributed compensation of earth fault current in large-scale rural area medium voltage cable network. First, the history and current state of the rural area medium voltage networks in Finland are reviewed. In considering the new requirements of customers and legislation, distribution network companies have decided to build weatherproof network, which increases the amount of cable network. PSCAD simulations have been used to verify how some factors such as the density of compensation coils, the share of decentralized compensation, the background network and the parallel resistance affect the earth fault current and how the earth fault current can be minimized during a fault condition. Also the effects of above mentioned factors to quantities measured by protection relays were investigated.