Economic Operation Optimization Of Photovoltaie-energy Storage Micro-grid Based On Events

In this paper,a photovoltaic-energy storage micro-grid which consists of photovoltaic cell arrays,batteries,inverters(including a grid-connected inverter and a bi-directional inverter)and loads is studied.In addition,the micro-grid is allowed to purchase electricity from or sell electricity to the power grid.In order to optimize the economic operation of photovoltaic-energy storage micro-grid,considering the randomness of photovoltaic output power,electricity load and electricity price,a rolling optimization scheduling method based on events-driven is proposed.The researches are as follows:Firstly,based on the operation characteristics of photovoltaic-energy storage micro-grid,events are proposed,including the variation of photovoltaic output power,the variation of electricity load and the variation of electricity price,and its expression are given.Secondly,the scheduling period is divided into several rolling windows based on events.The length of each rolling window may different.A rolling optimization model of micro-grid based on a rolling horizon optimization framework is established.The objective function is to minimize the operational cost of micro-grid that includes the maintenance costs of both photovoltaic cell arrays and batteries,the penalty costs of batteries,electricity purchasing costs and electricity selling incomes.The constraints such as the power balance,the charging and discharging power limits of batteries,the SOC limits of batteries,the purchasing and selling power limits and the SOC update of batteries are considered.In addition,the nonlinear items in the constraints are linearized,and thus a Mix Integer Linear Programming formulation is obtained.When an event occurs,then re-schedule and re-adjust scheduling scheme.Otherwise,do not re-schedule and proceed according to original scheduling scheme.Finally,combining with the characteristics of rolling optimization model of micro-grid based on events,GAMS/CPLEX is used to solve the model.A case study is conducted with the utilization of the data of photovoltaic output power,electricity load and electricity price.The rolling optimization based on events is compared with the global optimization under five different scenarios.The results verify the effectiveness of the proposed method.