Voltage Stability Improvement of Microgrids Using Local Control Optimization

Stability challenges in Microgrids (MGs) usually arise from low inertia of Distributed Generation (DG). In this paper, a voltage stability improvement method is proposed in order to improve MG operation. Voltage Stability Index (VSI) is applied to evaluate and improve voltage stability of MGs including different types of DGs. A new hybrid optimization is introduced to find the optimal operation of autonomous MG and to improve VSI. Operational optimization is performed by finding optimal droop parameters of DGs and sitting wind DGs to reduce energy generation cost. Optimization is defined as a multi-objective function and a hybrid HS-GA algorithm is applied to solve the optimization problem. A new power flow formulation is also proposed in which the steady state frequency, reference frequency, droop coefficients and, reference voltage of droop based DGs are considered as optimization variables. Results of proposed approach are compared with other methods for 33 and 69-bus IEEE systems using MATLAB software. Results prove the efficiency of proposed approach for operational improvement of MGs.