Research On The Optimal Allocation And Economic Operation Model For Storage Energy In Microgrids

Because distributed power has the characteristics of intermittent andfluctuating output power in microgrid, which prevents the development of newenergy, with renewable energy applications continuing to expand the scale, thisproblem need to be solved. The excess energy from distributed power can bestored by the energy storage device in microgrid, and be released in the peakload. Moreover, the energy storage can also make up the disadvantages ofintermittent and fluctuating power output for the renewable energy, solve therenewable energy accessing problem fundamentally, and make renewableenergy access to grid smoothly. Therefore, it has the vital significance andnecessary to develop and research the optimal configuration and operationtheory of energy storage in microgrid.In the current research on engery storage allocation and operation inmicrogrid, these studies do not consider how to make full use of wind and solarcomplementary characteristics, less considering the constraint conditions of thebattery charge and discharge times and lacking of theoretical study of theoptimized allocation of the super capacitor and battery hybrid energy storage.The main contents of this paper are as follows:(1) For the independent wind-solar-diesel-battery capacity allocationproblem, the article considers the wind and solar complementary features thatthe daylight has strong sunshine and low wind speed; the night has high windspeed and weak light. Through the rational allocation capacity of wind turbineand photovoltaic module, can make the output power of the wind and solarcomplementary power generation system close to the load curve, enhance thematching between wind and solar complementary power generation system andload. This method improves the supplying reliability of power system, reducesthe configured capacity of battery and diesel generator, decreases cycle timesand discharging depth of battery.(2) For the disadvantage of distributed power’s randomness and volatilityto configure capacitor and battery hybrid energy storage system, by analysisingload characteristic, the article gives the hybrid energy storage system total capacity configuration method. The optimization objective function is thelowest total cost of the hybrid energy storage system, For the two decisionvariables of quantity and batch element in the objective function, respectively,the article puts forward the calculation method of based on Ragone curve andthe equivalent cycle life, transformes the problem of solving the two decisionvariables to solve the time constant T, then the objective function istransformed into the single variable nonlinear function about time constant T.The problem is solved by the optimization toolbox of MATLAB, which givessuper capacitor and battery’s ratio of capacity and power. The results show thatthe hybrid energy storage cost is33.8%of the single battery energy storage cost,improve greatly the energy storage economy.(3) the paper established a mathematical model of Microgrid economicaloperation, which includes the wind turbine, photovoltaic components, dieselgenerators, fuel cells, energy storage and load, considering the constraints ofmicro-sources and energy storage device. Genetic algorithm is used to achievethe minimum comprehensive cost of microgrid system.