The Operation Strategy And Optimal Planning Method Of The Stand-alone Microgrid Including Wind Turbine,Photovoltaic,Hydro Turbine,Diesel Generator And Energy Storage System

With the aggravation of energy crisis and environmental crisis,renewable energy sources have become increasingly significant in recent years.As an important means to realize the energetic complementarity and improve the efficiency of renewable resources,the stand-alone microgrid system gains increasingly attention,especially in islands and remote areas.Compared with the traditional power network,the standalone microgrid system is more complicated,and has more multiple power and more dispersed load distribution,so the allocation of distributed generation would affect the energy efficiency,the power supply reliability and the power quality.Therefore,the planning of microgrid is of great significant.The main work of the paper is as follow:(1)Aiming at the shortage of traditional hard cycle operation strategy which has ignored the power flow and node voltage constraints,the two novel coordinated operation strategies have been proposed,including the modified coordinated operation strategy and the two-step operation strategy.In the modified coordinated operation strategy,energy storage system is invested by the distribution company,and diesel generators and energy storage system are allowed to take turns to be the main power supply and provide frequency/voltage reference.In this strategy,the reactive power adjustment though the bidirectional converter system of energy storage system is used to regulate voltage.In the two-step operation strategy,energy storage system is invested by the distributed generation owner,which shares the same integration node with the distributed generation,and the absorption of distributed power by energy storage system as well as the reactive power adjustment though its power control system are used to regulate voltage.The case study proves the effectiveness of these two methods.(2)For the medium-voltage stand-alone microgrid,a new optimal planning model considering economic,environmental and reliable benefits based on the single benefit subject is proposed.In the model,the utilization rate constraint of renewable sources is taken into account,for purpose of searching the optimal allocation of microgrid with guarantying the utilization of renewable sources.The case study shows the feasibility of the proposed optimal planning model and analyses the affection of diesel price,the utilization rate constraint of renewable sources and the investment of distributed generation.(3)Based on the interest conflict of the distribution company and the distributed generation owner,a new multi-objective optimal planning model is formulated for medium voltage stand-alone microgrid system.Considering that few rules and regulations were made to standardize the contract price between the distribution company and the distributed generation owner,the contract electricity price between the distribution company and the distributed generation owner as well as the capacity and location of distributed generation and energy storage system are selected as the optimization variables.The case study proves the effectiveness of the model and analyses the influence of different operation mode of system and the investment mode of energy storage system.