Abstract:
One solution to confront the intermittent nature of renewable energies is to utilize energy storage systems (ESSs) in microgrids (MGs). This paper studies an expansion planning problem to report the optimal size of the storage system. The objective function includes the investment cost of the storage system and the operating cost. Adding a storage system to an MG not only can be considered as the investment cost, but also it benefits the system in reducing the operating cost. Therefore, the main target is to minimize the sum of the later items. To ensure the practical capability of solutions, storage management systems (SMS) are used for modeling the storage system. The mixed-integer programming (MIP) method is also employed to formulate the expansion planning problem. The storage system cooperates with thermal units to maximize the obtained economic benefits and minimize the costs. Numerical analysis is performed and a mathematical model is proposed to evaluate an optimal size of the storage system. The numerical results show that a larger storage system does not necessarily mean gaining more economic benefits. There is an optimal condition based on which the storage system is designed and installed. It is found that selecting larger sizes of the storage system imposes higher expansion costs on the MG.
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