Study Of Load Optimal Dispatching For Virtual Power Plant

With energy crisis and environmental issues becoming increasingly serious,the development of renewable energies has been paid more and more attention by the countries around the world. However, the integration of random and intermittent renewable energies will introduce new difficulties in the secure and economic operation of power systems. Virtual power plant(VPP) can integrate large-scale geographically dispersed and various types of distributed renewable energies and loads effectively, break the boundaries between power side and load side and improve power supply reliability, it is an important means to solve the problems that renewable energies were integrated into the grid. Based on promoting the application that integrating scale renewable energies into the electric power system, this paper introduces the concept of VPP and conducted study of load optimal dispatching for VPP.First, against the problems when small scale renewable energies were connected to the grid. On the basis of analyzing the power generation cost of the distributed generator (DG) in the VPP, a VPP economic optimal dispatch model with the environmental benefits is established, and an operation strategy of VPP based on the seasonal characteristics of small hydropower is designed. With the goal of actual output of VPP tracking planning output and minimizing generation and environmental cost of VPP in each period, the output power of the DG in the VPP is obtained by the particle swarm algorithm. The simulation results shows that small scale renewable energies and some controllable DGs are built into VPP through load optimal dispatching can reduce the effect of renewable energies’ output fluctuation on grid and the total cost of DG.Second, Time-of-use power price of grid can stimulate VPP to participate in the grid shifting load, reduce the cost of power generation and get better benefits. Against the uncertainty of the output power when a large scale renewable energy were connected to the grid and the effect of grid time-of-use power price to the generation side, an operating strategy of VPP based on the time-of-use power price was designed. With the goal of maximizing the profits in each period, an economic optimal dispatch model of VPP based on time-of-use power price is established. The output power of each energy resource of VPP is obtained by the particle swarm algorithm The simulation result shows the rationality of the established model, and shows that VPP based on time-of-use power price can get better economy and power quality through using pumped storage and energy storage battery for joint operation and load optimal dispatching when large scale renewable energy is connected to the grid.Finally, Against the dilemma that large-scale renewable energies consumption level is limited, this paper brought load side demand response into load optimal dispatching for VPP on account of the mechanism of generation and load side. Load curve was predicted by principle of user response considering consumer psychology. Considering the effects that load side demand response and generation side conventional power had influenced on renewable energies consumption and system operation, with the goal of maximizing the renewable energies consumption and minimizing system operation and environmental costs, a multi-objective load optimal dispatching model based on the coordination between generation side and load side. Multi-objective was transformed into single objective by target multiplication and division methods. Then adaptive immune vaccine algorithm was used to solve the model. The results of actual calculation example indicated the VPP which considering coordinated operation of load side and generation side through load optimal dispatching can reduce system operation and environmental costs effectively, and improve renewable energies utilization.