Protective coordination of main and backup overcurrent relays with different operating modes of active super-conducting current controller

Abstract

Active superconducting current controllers (ASCCs) are new generation of series compensators, which can also be categorised as fault current limiters because of their ability to decrease the fault current continuously. Although the performance of the ASCCs in different operating modes introduces a limiting impedance in series with the network, it can degrade the operation of the overcurrent relays (OCRs). In this paper the ASCC modelling and its control strategy for fault detection and converter operation is investigated. The simulation of a typical three-phase ASCC shows the effect of the ASCC on fault current limiting and confirms the operation of the control system. The impact of different modes of ASCC on the operation of the main and backup OCRs is studied through the simulation of a typical distribution system . Simulation results confirm that the protective coordination of different modes of the ASCC is achieved by modifying both the time dial and pickup current parameters of the OCRs