Abstract:

Microgrid, integrated with generation, storage, and load, either produces or consumes power. When power consumption increases at a microgrid's point of common coupling (PCC), the entire power distribution network is at risk of voltage collapse. Critical load impedance and continuation power flow were currently used to assess static voltage stability in power systems. Critical load impedance was derived based on a Thevenin equivalent circuit model, but information used to derive the equivalent circuit is usually not available and accurate parameter estimation takes time. Because continuation power flow used approximation, this method is not accurate unless close to voltage collapse. To predict impending voltage collapse for a microgrid, this paper introduces a static voltage stability detector that only uses local measurements available at the microgrid's PCC. A voltage stability index depicts the distance of microgrid's power consumption from voltage collapse. Therefore, microgrid manager needs to take more urgent action when the index is smaller. Furthermore, microgrid manager predicts voltage stability index once a local load forecast is available. Compared with existing techniques, this voltage stability detector is accurate and easy to implement for microgrids in a power distribution network.