Nondetection Zone on Synchronous Generator Protection Using Voltage and Frequency Relay as Medium Power Distributed Generation

Distributed Generation (DG) become popular to locally supply grid connected load. One advantage of DG is a grid support reducing the cost in transmission and distribution system. The problem relates to DG is when the loss of grid occurs, the DG will operate stand-alone and supply the rest of the load. The main topic of the research is the ability of generator protection system to detect the loss of grid condition for medium power DG. Nondetection zone (NDZ) is like a blind spot causing the protection system can not be able to detect the fault. NDZ of a synchronous generator can be estimated by voltage and frequency relay by simulation. The result shows that medium power DG with governor and AVR mechanism indicated that the protection of loss of grid only needed frequency relay because voltage relay has a wider NDZ. NDZ of frequency relay with AVR mechanism for resistive-inductive pf 0.8 load is at the value of active power imbalance (ΔP) -0.0425 pu till 0.0972 pu and the value of reactive power imbalance (ΔQ) -0.0319 pu till 0.0728 pu.