Impact of Inverter Interfaced DG Control Schemes on Distributed Network Protection

Abstract

Inverter interfaced distributed generation is emerging to be an attractive renewable source to the distribution grid. However, control schemes utilized in inverter interfaced distributed generation (IIDG) leads to complications in fault current estimation in the distribution network, which might cause a threat or profound impact on conventional protection system. Conventional protection schemes and tactics require more extensive investigation. The current version of IEEE 1547 would not provide any comprehensive solution for fault identification, especially in presence of DGs. It is, therefore, essential to study fault feeding characteristics of IIDG which solely depend upon controller types and its design parameters. Two types of widely used control schemes, current control scheme and voltage control scheme are thoroughly studied in this paper. In the current control scheme, IIDG act as a current source for the ac grid and for the voltage control scheme, it behaves as a voltage source in the absence of ac grid. A simplified single line distribution network model was examined to verify the controller impact on different types of fault. A novel controller is also proposed to identify the faults in distribution grid supported with IIDG.