Analysis of protection performance in UHV transmission line with multi series capacitors compensation

Series capacitor can enhance transmission capability of power grid and optimize the power flowed to improve the transient stability of power systems. However, they change the magnitudes and the directions of fault voltages and currents in series compensated networks and impact the protection performances. This paper analyses the fault electric quantity characteristics and discusses the operation behaviors of protection relays on transmission lines with multi series capacitors. Some suggestions for improving the protection performance are proposed. The analysis results were tested extensively using RTDS (Real-time Digital Simulator) in a transmission line model. The simulation results show that the suggestions can improve the performance of protection relays applied in UHV transmission line with multi-series capacitors.