A New Impedance-Based Main and Backup Protection Scheme for Active Distribution Lines in AC Microgrids

Microgrids active characteristics such as grid-connected or islanded operation mode, the distributed generators with an intermittent nature, and bidirectional power flow in distribution lines lead to malfunction of traditional protection schemes. In this article, impedance-based fault detection scheme is proposed main microgrids by applying equivalent circuits for doubly-fed lines. scheme, relay location data positive sequence voltage absolute value other end line are used. It can detect even high impedance faults modes. robust against load generation uncertainties network reconfigurations. Low sampling rate minimum exchange among advantages scheme. Moreover, a backup based on conductance variations suggested. No requirement communication link distinguished advantage The schemes have been simulated using PSCAD MATLAB software results confirmed their validity.