Research On Operation Strategy And Optimal Allocation Of Energy Storage System In Distribution Networks With High PV Penetration

With shortage of fossil fuel and growing environmental pollution,the development of renewable energy such as PV has attracted wide attention from all over the world.But the problems such as the impact of output fluctuation on the grid and voltage violation caused by high PV penetration pose huge challenges to the security and stable operation of distribution networks.With the rapid development of energy storage system,it has become an effective means to solve these problems.The comprehensive control strategy of energy storage system and the coordinated operation strategy of PV-battery-load are proposed in this paper.On this basis,considering the coupling relationship between operation and allocation,the multi-stage dynamic optimal allocation of energy storage system is proposed.The specific contents are as follows:(1)Firstly,this paper proposes a bi-level operation control strategy of supercapacitors and batteries.At the upper-level,a fuzzy-logic based variable step-size control strategy of supercapacitors is proposed to smooth PV power fluctuation and the impact of PV forecasting error is eliminated by adjusting supercapacitors'power in real time.The smoothed PV output are employed at the lower-level.Considering batteries'remaining lifetime,state of charge,operating costs,voltage sensitivity factor,bus voltages and peak-valley electricity price,the controller chooses the optimal battery to realize voltage management and price arbitrage.This part lays the foundation of PV-battery-load coordinated operation control and energy storage system optimal allocation.(2)Then,based on the operation control strategy of batteries,this paper combines PV inverters'reactive power control and consumer-side active loads control and proposes the rule-based and optimal-based coordinated operation strategies of PV-battery-load.When the bus voltages exceed the limits,the rule-based control strategy operates according to the order of PV reactive power compensation,battery voltage management and active load control;the optimal-based control strategy operates the PV reactive power compensation preferentially,if the voltage problems still exist,the battery and active load will be optimally controlled with the goal of minimizing the operating cost.The advantages and application scenarios of two control strategies are analyzed and compared through example simulation.(3)Finally,considering the proposed operation control strategy,the growth of PV penetration and loads and the time value of money during investment planning period,this paper establishes a multi-stage dynamic optimal allocation model of energy storage system.The model firstly combines the genetic algorithm with the gravity search algorithm to solve a single-stage static optimal allocation problem and gets the installation location and capacity of energy storage system in target year.Then,using the results as constraints,the heuristic rule-based multi-path forward dynamic programming method is used to determine the specific investment time of each equipment.The effectiveness of the method is verified by example simulation.And this method provides theoretical support for the optimal allocation of energy storage system in practice.