Fault current limiting capability of Interline Power Flow Controller in Low Voltage 415V Distribution Networks

Process industrial loads are increasing due to expansion of existing manufacturing units. Increasing of loads will increase the power requirement which is reflected at the distribution level. Feeding the additional loads existing switchgear to be modified and for meeting load requirement additional source of distribution transformer to be added, which it may not be an economical solution. To meet the additional load requirement of industries, two transformers need to be operated in parallel in continuous mode. Bus fault current at LV switchgear is the main constrain with parallel operation of the distribution transformer. Due to increase in fault current, existing switchgears bus bar design capacities may not be adequate, generally in India fault current at LV side switchgear bus bars will be designed for 50kA withstanding capacity. Approach is to reduce the fault current below design fault current with parallel operation of transformers. This approach is mainly safeguard the switchgear equipment during parallel operation of transformers and also avoiding adding additional transformers in distribution network. This paper proposes the method of utilizing series FACTS device Interline Power Flow controller (IPFC), connected in LV side to control the power flow and reduce the fault current on switchgear bus bar during transformer parallel operation. The controller used as reference design fault current method and injected the required voltage in a distribution side during fault condition to achieve desired fault current. The distribution network consider for analysis is one of the Indian 800MW Thermal power plant Water system LV switchgear and analyzed short circuit current on switchgear bus bar with and without IPFC by using ETAP and MATLAB/SIMULINK model and compared the bus short circuit current for different ratings of transformers connected in parallel to LV switchgear.