A Research On The Optimal Allocation Of Energy Storage For Power System Integrated With Large-scale Wind Power

As fossil fuel shortage and environment pollution become more and more serious, wind power generation has experienced a rapid growth in recent years. However, due to its uncontrollable, stochastic, and variable characteristics, high wind power penetration brings great complexity in the power balance and stability control of power system. The flexible energy storages can help in power balance and energy balance of power system, and is an effective solution to improve the safe and economic operation, and renewable energy utilization of power system with lager-scale wind power integration.The multiple time-scales modeling of wind power output using discrete wavelet transformation (DWT) is proposed. The Time-Frequency characteristics of wind power fluctuations can be obtained by DWT, and then wind power nature under different time-scales can be analyzed. The advantage of analyzing wind power of different time-scales using DWT is verified by the results. The operation modes of some mature energy storages in the power system with wind power integration are introduced based on their characteristics, and the idea of the optimal allocation of energy storages is proposed. The three special researches on the optimal allocation of energy storage based on smoothing the short-time wind power fluctuation, the optimal allocation of energy storage based on mitigating wind power forecast errors, the optimal allocation of energy storage based on peak load regulation of power system with wind power integration are carried out. Then, based on the three special researches, the methodology of the optimal allocation of multiple energy storages using decomposition-coordination method for power system with wind power integration is presented.This paper studies the optimal allocation methodology of the battery-based energy storage (BESS) capacity based on smoothing the short-time wind power fluctuation, and proposes a novel optimal operation strategy for BESS to limit the fluctuation between two adjacent time intervals. The optimal operation strategy considers the prospective effect of the future time intervals during Tval (PSPE), and a multi-stage recursion using sequential rolling planning is applied here to solve the problem. The effectiveness of the optimal operation strategy has been tested by using actual power out data of a wind farm. The results show that wind power fluctuation can be improved greatly, and PSPE performs better and more effective than the traditional operation strategy in operation and coordination of energy storage system.This paper studies the optimal allocation methodology of battery-based energy storage (BESS) capacity based on mitigating wind power forecast errors, and proposes a novel methodology to optimize BESS capacity for wind power forecast errors in the bulk power system. In the design of energy storage allocation capacity, the proposed method not only considers the wind power forecast errors, but also takes into account the load characteristics and the regulating ability of conventional units. After calculating the wind power forecast error which can be compensated by conventional units, the scheduled appropriate wind power forecast error to be compensated by BESS is obtained. Based on the scheduled appropriate wind power forecast errors compensated by BESS, the optimal energy state of BESS is designed, which enables BESS to compensate wind power forecast errors maximally. Then, the daily system operation is simulated in details over a year to obtain the system operation costs. A comparison between the savings in operating costs and the investment cost of a given BESS capacity is used to determine the optimal capacity of BESS. The effectiveness of the optimal approach has been tested by numerical examples.This paper studies the optimal allocation methodology of energy storage based on peak load regulation of power system with wind power integration. Using well-being analysis theory, the paper presents a peak load regulation capacity requirement model for power system integrated with wind power. The peak load regulation capacity model illustrates the effects of wind power on the required peak load regulation capacity. Based on the peak load regulation capacity requirement model for wind power, a model for optimizing the pumped storage power station capacity for peak load regulation of power system with wind power integration is proposed. The model takes into account the costs of energy storage, operation cost and capacity cost savings of the system, and the net benefits are evaluated as the objective. The case studies were carried out for a system, and the results verified the effectiveness and accuracy of the presented model.According to the required energy storages characteristics of wind power output under different time-scales, the necessity of optimizing multiple energy storages considering their coupling effects is presented. Based on the above three special researches, the optimal allocation methodology of multiple energy storages in power system with wind power integration using decomposition-coordination method is proposed. According to wind power components under different time-scales, the optimal allocation of multiple energy storages can be decomposed to be three sub-models. Based on the separate optimization of sub-models, the method considers the coupling effects between different energy storages, and more global optimization results can be obtained.