Research On Economic Operation Problem Of Micro-grid Based On Flow Battery

It is of great significance for the power industry, which is the largest consumer of theprimary energy, to advance the smart grid construction so that the power system ispossessed of security, flexibility, cleanliness and economy. During the construction of smartgrid, the application of energy storage technology will have broad development space.Introducing energy storage technology will not only improve the capability of peak loadshifting so that we can effectively realize demand management, but also promote theapplication of renewable energy, such as wind energy and solar energy, so that thecompatibility to be connected to the power grid of the renewable energy and the stability ofpower system operation can be improved. The basic requirements for the energy storage,which is applied to peak load shifting, smooth the intermission of renewable energy at thepower generation side and reduce the spinning reserve, include large energy storage, quickpower response, high storage efficiency, long lifespan, low operating cost and so on.Regarding that the property of flow battery can meet these basic requirements, it will havesome advantages over other storage battery to choose the flow battery.Based on the National Basic Research Program of China (2010CB227206) and(2009CB219702), this paper systematically discusses the problem of economic operation ofapplying flow battery to the microgrid, with the medium and low voltage distributionnetwork as the study object. Considering the application of the flow battery in the peak loadshifting with the ideal characteristics, an optimization and dispatching model, whichchooses the ideal effect of peak load shifting as the optimal goal, the energy stage andcapacity power configuration of the flow battery as the constraints, is built up and theapplicability of the generic algorithm and the reasonability of the model are validated byrunning simulation with the generic algorithm and the theoretic algorithm respectively.In order to consider the economy of the power grid, this paper takes the power and thepower consumers, the two different trading subjects in the power market, as the objects toanalyze. With various kinds of factors, such as the counts of charging and discharging, thestate of charge, during the actual operation of the flow battery considered, the paper alsotakes the daily investment expense of the flow battery as the constraints and then do themodeling research to get two models, one of which targets the safe and economic operationof the power grid while the other one targets the side demand management. Economic operation of microgrid is the main problem of optimal management of themicrogrid energy. with the flow battery and distributed power source modeled together andthe different aspects of the economic costs selectively considered, an optimal model isproposed according to constraints of power of units in microgrid and the state capacity offlow battery. Taking use of the generic algorithm to models established above, theoptimization of controls towards charging-discharging power of a flow battery, loaddistribution and power exchange with the grid has been made, and finally the economicanalysis of microgrids that equipped with different batteries in different power grid tradingmodes, together with the optimal allocation for the power and capacity of the flow battery,is illustrated in this article.