Computation of stability delay margins of microgrids with implementation of two types of superconducting magnetic energy storage systems

The extensive integration of renewable energy sources (RESs) into the microgrid (MG) might influence frequency fluctuations within the system. Furthermore, time delays are inevitable, as MGs encounter significant time delays stemming from the extensive utilization of phasor measurement units and communication networks employed to transmit data from the power facility to the central controller. These delays may reduce controller effectiveness and destabilize the MG’s frequency. To assess the stability delay margin (SDM) of an isolated MG with and without superconducting magnetic energy storage (SMES), this research uses a Direct method to determine the SDM, the maximum delay the system can withstand before instability. The proposed method eliminates the exponential terms e − s τ from the characteristic polynomial (CP) and gives an analytical expression to the delay margin. Standard polynomial may calculate the crossover frequencies and exact SDMs by omitting the exponential term. The main purpose of this study is to investigate the delay-dependent stability and to compute the SDM of MGs integrated with two advanced SMES units, MG-SMES Model 1 (linear configuration) and Model 2 (dynamic configuration). In this paper we present a comprehensive quantitative evaluation of SDMs for a wide variety of proportional-integral (PI) controller gains. The results show that the addition of SMES units greatly improves the reliability of the system, and Model 2 is always better than Model 1. The SMES Model 2 has a stability cushion, which is 32.244–53.123% greater than that of Model 1. Time-domain simulations and the Quasi-polynomial Mapping-based Root Finder (QPmR) approach verify the SDM results. This illustrates that the SMES integration can successfully reduce the destabilizing effects of communication delays in modern MGs.