Capacity Assessment Of Intermittent Energy Considering Energy Storage

Wind power and photovoltaic are the world’s fastest growing and have the most economic benefits of all kinds of intermittent energy generation technologies, as an alternative energy of the future, the major issue of intermittent energy generation technologies in China currently is that it is only regarded as substitute energy that provides certain consumption value. So how to estimate the capacity value of intermittent energy and improve it’s effect in the balance of the grid is the key to break through the bottleneck. In this paper, capacity credit assessment of intermittent energy considering energy storage is discussed. Taking the wind power as an example, the best storage allocation method is searched from the view of economic value.1) Assessment of power system reliability. Reliability assessment method can be classified as analytical method and simulation, a basis of analytical method can be put as general state, enumeration method, while the simulation method commonly uses component sampling method, mainly using the Monte Carlo simulation method. The two-state model of conventional units is introduced, and the LOLE is used as the index of system reliability.2) Method of capacity credit assessment. The capacity credit can be understanded from the load side and the generation side. The effective load carrying capability is recommended as the index of capacity credit in this paper. Then the basic principle of secant method is described. The basic flow of the Monte Carlo simulation to calculate the capacity credit is introduced, and then the method is verified in the IEEE89 system, using wind power as an example. It can be seen that the capacity of wind power is relevant with the matching degree of output and load, under normal circumstances, the capacity credit of wind power stays at a low level.3) Study of storage allocation strategy. Study on the characteristics of main kinds of energy storage, analysis its feasibility for improving capacity credit of wind power, method of capacity credit calculation is proposed againsts the fixed power and capacity of energy storage. The basic idea is finding the best strategy through the Newton iterative method, the the capacity credit of the very system can be gotten. Aiming at the optimization problem, particle swarm optimization algorithm based on exterior point penalty function method is introduced. In the case, the result calculated by different power and capacity are analyzed, it can be seen that the capacity credit of intermittent varies with the capacity of energy storage.4) Analysis of benefit-cost of wind power system considering energy storage. The cost of energy storage is related to its power and capacity, and the benefit is devided into two aspects, the energy efficiency and environmental benefits. The unit capacity credit benefit is proposed to evaluate the economic value of wind power considering energy storage. In the case, several energy storage scheme is compared through the view of economic value, and it is providing a theoretical reference for the construction of wind farms.