Mitigation of Power and Frequency Instability to Improve Load Sharing Among Distributed Inverters in Microgrid Systems

This paper presents the design of a power system stabilizer (PSS) for stability improvement of a droop-controlled inverter-based microgrid systems. For faster power sharing, high droop gains are required, but increasing the droop gains degrades the system stability. Hence, there is a tradeoff between the faster load sharing and system stability. An answer to the given problem is presented in this paper by developing a PSS for inverter-based microgrid. The proposed stabilizer provides sufficient damping to the low-frequency oscillation even at higher value of droop gains which are usually unstable otherwise. The PSS designed in this paper is a generalized one and a step-by-step method to select the PSS parameters is also presented. Time domain simulation, experimental results, and eigenvalue analysis are presented for verification of the proposed controller.