Voltage Stability Indices for Islanded Microgrids

Microgrid voltage stability is being challenged as the power output of renewable energy generation is not as stable as the traditional generation used in the main grid. Therefore, the choice of voltage stability analysis techniques plays an important role in the stable operation of the microgrid. This paper presents a comparative study on the voltage stability indices (VSI) measured using different techniques for an islanded microgrid composed of various renewable energy resources. Four dominant VSI techniques for microgrids are compared in this paper. An islanded microgrid system is modelled based on the IEEE-14-bus system in PSCAD. The model is used to evaluate the stability results analyzed by different VSIs. Two simulation scenarios are applied, including changing the output power of distributed generations (DGs) and the connection position of the DGs. A ranking of bus voltage stability is analyzed based on the simulation and the VSI calculation. Finally, the advantages and disadvantages of each technique are discussed based on the simulation results.