Generation reliability assessment of stand-alone hybrid power system — A case study

Many rural communities are not able to access the main power grid supply due to high cost associated with grid extension. The stand-alone renewable energy based hybrid power system is a significant adaptation to cope with increasing power demand along with environmental consideration in rural communities. In such a system, determining the correct size and capacity of renewable generating units to supply continuous and reliable electricity is of great importance. For this purpose, the reliability of a standalone renewable energy based hybrid generation system is evaluated in this paper to meet the load demand of a residential building located in St. John's, Newfoundland and Labrador (NL), Canada. A probabilistic reliability evaluation approach, Monte Carlo simulation technique is adopted to compute the reliability index, Loss of Load Probability (LOLP) utilizing the generation models, renewable resources data and load demand data for a whole year. The main advantage of this technique over the deterministic approaches is its ability to provide quantitative reliability assessment taking the actual system behavior into consideration. The system reliability is evaluated based on LOLP values, which are computed considering different combinations of renewable energy mixtures in the generation system. In this paper, three dominant renewable energy resources, solar, wind and hydro, are taken into consideration, and the most reliable energy mixture is determined. Furthermore, system reliability is assessed considering variation in total generation capacity. This type of analyses will be useful for the system designers to determine total capacity and optimum sizing of the system before installation.