A comprehensive reliability assessment index system for regional grid with a large renewable energy penetration

In recent years, the utilization of renewable resources such as wind and solar to generate electrical power has been growing due to the two main driving forces: environmental advantages coupled with financial benefits. Owing to the negligible operating cost, dropping investment and zero-pollution, the renewable energy (RE) technologies have a rapid development. As a result, renewable energy will have a larger penetration rate in regional grid's generation capacity. At the same time, the integration of a large amount of renewable energy in regional grid creates a series of reliability problems because of its intermittent and stochastic nature. How to roundly and accurately assess the impact of the injection of renewable energy on system reliability has ever been a concerned problem in long-term. So far the concept of Capacity Credit (CC) is the most widely used and accepted index to measure the reliability value of wind energy in the power system planning field. However, the kind of assessment is too simple and too one-sided to fully reflect the influence of RE. In this paper, we propose a novel index system which can be easily calculated, aiming at roundly and effectively evaluate the impact on reliability of renewable energy's fluctuation. Numerical test cases are used to validate the effect of this index system.