Dual-Layer Based Microgrid Protection Using Voltage Synchrophasors

Distribution networks have been facing many changes in recent years, mainly considering their integration with microgrids. Their combined use has several operational challenges, such as power quality issues, system instability, and protection problems. Considering the decreased costs of phasor measurement units (PMUs), many protection schemes have been proposed using these devices. Thus, this paper presents a dual-layer protection for microgrids based on the RMS value of voltage measurements. The first layer uses conventional overcurrent relays to detect faults. In case of failure or delayed operation of these relays, a second layer device should operate, which utilizes the voltage from strategically allocated PMUs. In this context, if necessary, the second layer device sends a remote trip signal. The proposed method was evaluated for all fault types, considering different microgrid operation modes and power injection from distributed generators. Overall, the dual-layer protection significantly improved the microgrid protection reliability, regardless of its operation mode.