Small Scale Stability of Isolated Rural Microgrid Based on Load Characteristics

Abstract

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 vulnerable 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. EPRI Load modeling has been considered based on aggregate index calculation. The system is studied for step increase/decrease in load as well as input power to the wind energy system and also the post effect of voltage & frequency change on the load with its influence on the system is considered for study purpose. The isolated microgrid proposed has wind energy system with PMSG and biogas genset (BG) with synchronous generator (SG). The system is designed in such a way that any increase/decrease in load and input power to wind is taken up by the biogas system. No additional reactive power compensator is envisaged. Accordingly, the controllers are tuned using Integral Square Error criterion for mitigate variation in load voltage & frequency.