Probabilistic static voltage stability evaluation of microgrid with droop-controlled distributed generations

Islanded microgrids is vulnerable to instability owing to its small scale and low inertia. To analysis the probabilistic static voltage stability of islanded microgrids with droop-controlled distributed generations (DG), a method based on singular value decomposition and probabilistic load flow is adopted. The deterministic load flow model of the islanded microgrid is presented considering the philosophy of droop-controlled DGs and static voltage/frequency characteristics of loads. Newton-Raphson approach is adopted to solve the flow equations. Through singular value decomposition of Jacobian matrix of the load flow calculation, the minimum singular value can be obtained as the index of static voltage stability for IMG. And the right singular vector corresponding to the minimum singular value is also analyzed to indicate the sensitive voltages and areas. Monte Carlo method is performed to simulate the stochastic characteristics of intermittent DG output and load power and the probabilistic characteristics of minimum singular value as well as the right singular vector are obtained. The proposed method is verified on an islanding microgrid modified from IEEE33 system.