Optimal Dispatch And Bidding Strategy Of Virtual Power Plant With Risk Management

In recent years,numbers of distributed generators have been integrated into the power system;they can support the power system in the demand side,and provide various clean energies.However,the installed capacity of distributed generators is small and their numbers are huge.Thus,they are different to be dispatched by the independent system operators.Even worse,most distributed generators generate electricity by wind,solar and other renewable energy,their outputs are random.As the reasons above,virtual power plant technology which can manage distributed generators centralized,balance the risk and uncertainty has received more and more attention.This paper focuses on the virtual power plant technology,introduces the new theories and methods in the uncertainty optimization and risk management,considers the random sources and controllable sources in the virtual power plant,studies the sale and purchase problem under predetermined prices,coordination of energy and ancillary services problem,day-ahead bidding strategy problem,mid-term contract strategy problem and the estimation problem of the effects of virtual power plant on the power system.This paper tries to contribute the fields in virtual power plant operation and interaction.The main ideas and contributions of this paper are as follows:Considering the virtual power plant's risk management under various uncertainties,this paper employs the spectral risk measures which consider the decision maker's subjective risk aversion.The spectral risk measures build the spectral functions to quantize the risk aversion towards losses.Scenarios tree is built to simulate the possible value of random variables in the future.This paper proposed a dispatch model considers the spectral risk measures under time-of use electricity price.Stochastic optimization is used to solve the optimal dispatch and the risk index.Compared with other indexes like standard deviation,value at risk and conditional value at risk,the spectral risk measures can affect the subjective risk aversion of decision makers and help decision makers to find the optimal result with the most satisfactory.Considering the target of profit maximization and risk minimization,this paper first introduce the concept of economic capital and determine its requirement by the conditional cash flow at risk,then,a new profit-risk tradeoff is built by the index risk adjusted return on capital.Lastly,this paper proposes a bidding strategy of virtual power plant to maximize its risk adjusted return on capital,proposes an optimal dispatch model with risk adjusted return on capital threshold,and proposes a coordination dispatch model of energy and ancillary services.Considering the probability distributions of random variables are hard to predict,this paper uses interval optimization to establish the day-ahead bidding strategy and mid-term contract strategy.Interval optimization only considers the possible range of random variables,and ignores their exact possibility distributions.Interval optimization can determine and optimize the profit interval of virtual power plant.According to the pessimism degree of decision maker,the interval performance ordering is established,and it is used to find the most satisfied profit interval of decision makers.Considering the effects of renewable energy,virtual power plants on the future power system,an economic dispatch model considering the reliability constraint is proposed.This model takes the variable factors like generator outage,renewable power outputs,virtual power plant's energy sales and their correlation into account,and optimize the schedule of generators and the spinning reserve dispatch.Then risk contribution theory is adopted to estimate the contribution of virtual power plant,renewable energy and conventional generators on the total risk of power grid.Then,a cost allocation of spinning reserve method based on risk contribution is proposed.This method requires the risk sources to afford the spinning reserve costs according to their effects on the power system's total risk.The virtual power plant situation and distributed generator operating independently situation are compared to find out the meanings of virtual power plant.The two masterstrokes of this paper are market models and risk management.This paper studies the strategy to increase profit,quantize risk,reduce risk and allocate risk under the various uncertainties from local load,renewable energy and electricity prices.According to the market model and uncertainty environment the decision makers face to,suitable model in this paper can be adopted to determine the optimal dispatch and bidding strategy of the virtual power plant.