Research On Capacity Optimization And Energy Storage Control Strategy Of Photovoltaic-storage Combined Systems Based On Wavelet Packet Decomposition

With the continuous acceleration of social development and the increasing consumption of fossil energy,renewable energy such as photovoltaics has become the focus of attention.However,the inherent randomness and intermittent nature of photovoltaics have seriously affected the safe and stable operation of power systems.Effective control of photovoltaic power generation has become the key to achieving its large-scale promotion.In addition,it has become an inevitable trend for photovoltaic to participate in market competition with the further deepening of the power market reform.The key to the competitiveness of PV in the market is whether it can contribute to the contract.Therefore,reasonable energy storage configuration,effective control strategy,and thus the stabilization of photovoltaic power fluctuations and their contribution to the planning curve have important practical significance.In this paper,the energy storage is divided into six categories according to the speed of the existing energy storage response time,and the response frequency range corresponding to different energy storage is given.Based on the proposed energy storage classification,the power demand signal of photovoltaic power station is divided into several levels by wavelet transform,and various energy storage capacity requirements satisfying the power compensation requirements are obtained by spectrum analysis method.In this way,the fine allocation of energy storage capacity of photovoltaic power plants can be realized.A Photovoltaic Control Performance Standard(PCPS)is proposed,which is based on the control power output deviation control of PV power station.Based on the proposed control performance evaluation criteria,taking the deviation between actual output and planned output of photovoltaic power plant as control objective,and subarea control according to the control threshold of photovoltaic output deviation,a sub-scenario energy storage control strategy suitable for PV power station output stabilization is proposed.Based on the hierarchical and multi-band division of the control power deviation signal by wavelet packet transform,the energy storage requirements in the corresponding frequency range are calculated,and the energy storage compensation power requirements are regulated and controlled according to the proposed control strategy.The simulation analysis of the characteristics of a PV power station in China shows that the proposed strategy can match the PV plant output curve with the expected plan,and verify the effectiveness and practicability of the proposed method.