Effective Application of Series FACTS Devices in Industrial 415V Distribution Networks

The power distribution network in small and medium scale industries is through a 415V switchgear fed from motor control center (MCC) through step down transformer of 11/415V kV or 33 kV /415 V. The designed fault current of switchgear in 415V side usually is at 50kA. However, the process loads are continuously increasing, due to this the fault current at the busbar of the switchgear increases beyond designed fault current, which may require the replacement of entire switchgear to the new design fault current. However, upgrading the existing switchgear is not an economical solution to the industries. Alternatively reducing the fault current at the busbar is feasible. In this paper, series FACTS devices, thyristor control series capacitor (TCSC) and static synchronous series compensator (SSSC) used to reduce the busbar fault current in 415V distribution network. Furthermore, this paper discusses the innovative control logic, which is derived based on reference fault current (designed fault current) comparing with actual fault current in closed loop system to make reduction in fault current below designed fault current. Case study carried on 800 MW Thermal power plant Ash handling unit 415V switchgear.