Capacity Credit Evaluation Framework of Wind, Solar and Pumped Hydro Storage Considering Generation Adequacy and Flexibility

Conventional capacity credit evaluation only focuses on generation adequacy. It is assumed that as long as there is sufficient capacity in the system to cover demand, there will be enough facilities to keep real time balancing of system load and generation, namely system flexibility. However, recent studies have demonstrated that system may suffer from lack of flexibility at operational stage in the process of increasing penetration level of wind or solar. Thus, consideration of flexibility is necessary in capacity credit evaluation in high wind and solar penetrated system. In this work, the concept of capacity credit is extended with consideration of both generation adequacy and flexibility. Then, a framework to evaluate the capacity credit with the extended definition is proposed. The proposed framework is applied to evaluate the capacity credit of wind, solar and pumped hydro storage in the renewable energy zones proposed in AEMO’s Integrated System Plan. It is demonstrated that allowing wind and solar curtailment at operational stage can improve capacity credit to some extent. Also, coordination of wind, solar and pumped hydro storage can increase their capacity credits significantly.