Abstract:
To effectively smooth wind power output and realize the safe and economical operation of the energy storage system, a two-layer robust control strategy for energy storage clusters is proposed. In the system power distribution layer, the improved ensemble empirical mode decomposition is derived from analyzing high-frequency fluctuating power step by step, and an adaptive determination process of decomposition order based on grid-connected standards is proposed. It can analyze the local wind power well to reduce the low-frequency component, which is aliasing the energy storage power, reduce its power demand and operation burden, and solve the problem of low efficiency caused by the traditional method that the power signal needs to be completely decomposed. In the energy storage operation layer, considering the difference in state of charge (SOC) of energy storage units, an energy storage unit rotation control strategy based on power distribution interval is proposed, which can reduce the adjustment times of charge and discharge actions in the process while maintaining the consistency of SOC of energy storage units. On this basis, a coordinated control strategy based on three groups of energy storage clusters is proposed to effectively improve the robustness of imbalanced charge and discharge energy under the group control mode so that each energy storage unit can operate at the optimal depth of discharge (DOD) to make full use of its cycle life and prolonging its service life. Finally, the power data of a 50 MW wind farm is used to verify the effectiveness and superiority of the proposed strategy.