Effectiveness of Zeigler-Nicholas Method Based Parameter Tuning of Virtual Synchronous Generator for LFC in Low Inertia Islanded Microgrid

The growing penetration of intermittent renewable energy sources in the Microgrid is causing reduction in inertia which makes the Microgrid very sensitive to any load disturbances and leads to frequency instability. To provide sufficient inertia to Microgrid, the concept of Virtual Synchronous Generator (VSG) has emerged out as one of the best solutions in which the properties of a conventional power plant such as rotating mass and oscillation damping is emulated to mitigate the transients in the load frequency. VSG is very commonly modeled by PID controller that emulates the rotor, primary controller and secondary controller similar to a synchronous generator virtually. But proper tuning of the parameters of VSG / PID controller becomes challenging. In this paper, Zeigler-Nicholas (Z-N) method is used to tune the parameters as this method is effective even for systems for which mathematical model is unknown and requires only the transient response for the system parameter identification. The Z-N based VSG helps in robust control of load frequency by minimizing its overshoot, undershoot, settling time and rise time in case of sudden load deviation. Effectiveness of Z-N based VSG is established by comparing with Particle Swarm Optimization (PSO) tuned VSG for a low inertia islanded Microgrid.