| In order to cope with severe environmental pollution and promote a supply-side structural reform in the energy sector,China's power supply is developing towards a clean and decentralized trend.Meanwhile,a deepening reform in China's electric power system is driving the power industry to change from a single supply-side management model to a double-side overall management model for both demand and supply sides.With the development of energy internet technology,it is a trend that the demand side resources such as distributed power generation,demand response and electric vehicles will be included in the planning for the power system.However,power generation of these distributed energy resources are not controllable,and grid-connected with these resources may affect the security and stability of the power grid.Distributed energy from the generation side and the load side can be gathered through virtual power plants(VPPs)using controlling systems,so as to improve stability of power supply,promote clean energy consumption,achieve the goal of energy saving and emission reduction for the power industry.Under the marketization of electric power in China,based on a diversity of technology for different distributed power generation,energy storage systems as well as demand response,a power system optimal dispatching model involving with different types of VPPs is constructed in this paper,and the influence of different policies on the development of VPPs is analyzed through policy simulation at the macro level.Main contents of this paper is as follows:Firstly,definition,main structure and technical characteristics of VPPs are explained.Successful experiences and development differences of VPPs in Germany,European Union and USA are summarized.Based on international experience,three business models in China's market are put forward including a development model based on energy internet technology,a market transaction model based on demand response and a selling model by using a power sharing pool.Secondly,connotation and classification of the demand-response VPPs are expounded,and the complementary relationship of the price type and the incentive type demand response VPP participating in the market transaction is introduced;meanwhile the market operation mechanism and marketing strategy of the price type VPPs in the multi-level power market transaction is analyzed.Peak-valley time-of-use(TOU)price is an important strategy to implement price-type demand response VPPs.In this paper,an operation strategy of VPPs based on peak-valley TOU prices is designed,aiming to minimize the coal consumption,minimize the differences of peak and valley loads and maximize the satisfaction of the user's power consumption.A VPP economic dispatch model based on peak-valley TOU price is constructed.Fuzzy analytic hierarchy process(AHP)is applied to transform multiple objectives to a single objective optimization model.Simulation results reflects that the model is valid.The peak-valley TOU price implemented by electricity selling companies can reduce the coal consumption and narrow the difference of peak and valley loads,but increase user's electricity expenditure.Thirdly,a comprehensive VPP comprising a variety of distributed power generations,energy storage systems and demand response is constructed,and the output characteristics and operating cost and revenue of distributed energy are analyzed systematically.From simple to complex,the VPP internal optimal scheduling model considering uncertainty and environmental value is gradually designed.Firstly,an optimal operation model is established to maximize the VPPs operational benefits under the normal scenario.Then,based on the stochastic progr-amming theory and the scene analysis method,an VPP optimal dispatch model with the uncertainty of wind and photovoltaic power generation is established.Finally,considering environment value,a stochastic optimal dispatch model is set up to optimize the system running profit and minimize environment cost and value loss.Simulation results show that after considering the environmental value in the optimization target,the loss of treatment cost and environment value of the virtual power plants decrease obviously,and the uncertainty of wind power and photoelectric output not only affect the operation profit of the virtual power plant,but also increase the environment control cost and the value loss because of the increase of the external power purchase.Fourthly,a double-layer optimal dispatching model of VPPs and conventional power generations is constructed.First of all,considering a medium and long term trading and spot trading,an economic dispatch model for conventional power generation is established.Then,based on the double-layer optimization theory,a two-level economic dispatch model of virtual power plants and traditional power plants is established.Among them,aiming to minimize system scheduling cost,the upper layer is an economic dispatch model between VPPs and conventional thermal power plants.Under the goal of minimizing the VPP operation cost,the dispatch model at the lower level can generates the operation scheduling plan for each VPP.Thirdly,considering the uncertainty of user load,wind power and photoelectric power.a double-level stochastic economic dispatch model is established.Finally,in order to minimize environmental cost,a multi-objective double layer stochastic economic dispatch model is formed.From simple to complex,a double-layer stochastic dispatch model considering some uncertainty and environment value is gradually established based on the conventional economic dispatch model.The feasibility and applicability of the simulation analysis of the model are verified by selecting a power system in a designated region as the simulation object.Fifthly,a system dynamics model of VPP industry development is established.Firstly,based on the theory of system dynamics,a modeling purpose is expounded,and modeling boundary are set up to analyze key influencing factors.According to the VPP industry characteristics,the system of VPP industry development is divided into three subsystems including power supply and demand subsystem,VPP investment operation subsystem and resource and environment subsystem.Based on the interaction among the subsystems,some causality diagrams of each influence factor in the VPP development system are designed.Then,the complex system dynamics model for VPP industry development is established,and the equations and key parameter values among the internal variables of each subsystem are set up.Sixthly,based on the national energy policy,the scenario is simulated and analyzed for the energy policy affecting the development of VPPs.Firstly,based on the related data of economic society and electric power industry in Region A,the initial parameter values of the model are determined by the regression coefficient method and the arithmetic mean value method,and the validity of the model is tested.Secondly,the relevant national energy policies are combed,and the benchmark scenarios,basic policy scenarios and comprehensive policy scenarios are designed accordingly.Thirdly,the development trend of VPP industry under different situation is simulated and analyzed.Results show that power generation,installed capacity and profit of VPP in Region A increase in three policy scenarios,and following the accumulation of investment funds in research and development,the cost of generating electricity are significantly reduced and the efficiency of power generation is improved.The VPP rapid development will also help reduce carbon dioxide emissions and coal consumption in Region A significantly.Fourthly,the simulation results of VPP development under different policy scenarios are compared and analyzed.Results show that the VPPs have been developed rapidly in the integrated scenario.And the clean energy ratio,carbon dioxide emission from the power industry and the VPP installed capacity in Region A have reached the policy target setting value.Finally,corresponding suggestions are put forward to promote the rapid development of virtual power plants and improve resource environment in China. |
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