Dynamic Stability Study of Isolated Rural Microgrid Based on Load Characteristics

Rural areas are either weakly connected to grid or have no grid access. Therefore, hybrid system is only solution for continuous undisrupted power supply. Also these rural microgrids have specific types of load. Small systems are more susceptible to load disturbances and therefore, frequency and voltage variation have post disturbance effect on the system stability. Four different types of loads having exponential voltage and frequency characteristics are considered for the study. The aggregate indices are used in the load modeling. Load modeling has been done based on aggregate index calculation. For the small disturbance stability study composite load is considered having exponential load voltage and frequency characteristics. Further, the isolated microgrid proposed has Hydro with Induction generator, Diesel genset with PMSG and Photovoltaic System. The system is designed in such a way that Hydro and PVS is supplying constant active power and change in requirement of active power is supported by DG genset. Similarly, the inverter associated with PV system is modeled such that microgrids reactive power requirements are met. No other reactive power compensator is envisaged. Accordingly, the controllers are tuned using Integral Square Error criterion for minimum variation in load voltage & frequency.