Research On Optimization Of The Coordinated Operation Between Large-scale Energy Storage And Wind Power Generation

Due to the exhaustion of traditional fossil resources and the environment deterioration, wind power has significantly developed. Meanwhile, the stochastic nature of wind power brought great challenge to the secure operation of the power system, and moreover the large-scale development and long distance transmission of wind power further increase the risk of the power system secure operation.At the same time, the rapid development of energy storage in electric power system can be regarded as a special kind of power supply which could flexible respond in various time scales, and its large-scale application can provide a new approach to solve the above problems.ESS integrated in wind farms can effectively smooth the wind power fluctuation and improve the consumption of wind power. In this research, to solve the problem of optimal operation of wind-energy storage system, the following work including optimal planning, optimal real-time control and composite utilization of wind-energy storage system has been done to cover the research areas from system planning to the real-time operation and application. This research can effectively smooth the wind power fluctuation and achieve the economy of the wind-energy storage system, and meanwhile it explores the composite application pattern of the wind-energy storage system to make full use of size-limited energy storage system and improve its operation efficiency. Specifically, the main content of this research includes the following aspects:In terms of the optimization planning of wind-energy storage system, based on the analysis of influence factors of charging/discharging of ESS, a SOC section model is built to avoid the overcharge or over-discharge. Afterwards, a charging/discharging control strategy according to the SOC state is proposed with adjustive correction coefficient, which can effectively constrain overcharge or over-discharge to prolong the life span of the energy storage system. Then the operation cost of the wind-energy storage system is analyzed in view of the construction cost and operation cost, and accordingly the capacity of ESS is optimally determined which fully considers the dispatch requirement of wind power, life span of ESS and the total cost of ESS.In respect of real-time operation of the wind-energy storage system, the characteristic of wind power has been deeply analyzed, and accordingly a very short term prediction of wind power based on empirical mode decomposition (EMD) is presented, which shows that the very short term prediction can provide the future information for the look-ahead control of HESS. For this reason, wind power prediction is introduced into the control process of HESS, and a novel coordinated control Strategy for HESS using predicted information has been proposed. Considering the dominantfactors that influence HESS efficiency, a new charge and discharge strategy for HESS is built, and based on this, an optimization model is proposed to take SOC minimum-variance as objectivefunction and consider the constraints on charge/discharge power and HESS capacity. Afterwards, the coordinated control model for next look-ahead time section can be determined.In regard of the composite application of the wind- energy storage system, based on the spatial scale effect, this research analyzes the operation pattern and working mode of BESS integrated in adjacent wind farms, and points out that the fluctuation smoothing and peak shaving in power grid can be the appropriate for current BESS scale. After that, on basis of the charging and discharging strategy, the optimization function aiming to minimize the sum of total operation cost is built to determine the BESS capacity. At the same time, the feasibility for peak shaving is discussed according to the seasonal differences of wind power, the BESS operating strategy for fluctuation smoothing and peak shaving has been discussed, and the objective function that takes benefit maximization as target has been built. In this way, the operation modes of BESS can be optimized by the adjustment in accordance with the seasonal wind power features.