Predictive Analysis of Microgrid Reliability Using a Probabilistic Model of Protection System Operation

Protection continues to be an important factor in the development of microgrids. In this paper, an evaluation strategy is proposed to quantify the effects of deficient protection scheme on reliability indices in a microgrid. In particular, the evaluation strategy takes into account the trigger probability of protective actions under abnormal operating conditions, such as warranted trips, rejections, and malfunctions. This trigger probability in per unit time is defined as dynamic outage rate to distinguish the static outage rate (i.e., random outage rate). A probabilistic model is constructed by simulating system operating conditions to determine the trigger probability. The model can be characterized by the previously proposed virtual setting value, which can be determined by a predictive analysis to minimize the probability of incorrect protective actions under different operating conditions. With the proposed evaluation strategy, the significance of the impacts of the protection system, in terms of dynamic outage rate and static outage rate, on the operational reliability are demonstrated with a 400 V microgrid system.