Research On Transmission Network Planning Based On Conditional Value-at-Risk

With the increasing demand for electricity and the change of power load structure,higher requirements are put forward for the power supply capacity and reliability of power grid.A large number of new energy sources connecting to the grid and the separation of generation and transmission has brought more and more uncertainties on generation side.The reform of retail side,the adoption of demand side management technology,and the access of new loads such as electric vehicles also increase the difficulty of load forecasting and the uncertainty of load side.The reform of transmission and distribution pricing mechanism change the profit mode of the power grid,which will force the grid to improve the efficiency of investment and operation,which will bring new impacts and challenges to transmission network planning.Therefore,it is significant to research the transmission network planning method suitable for the current situation of power development.Aiming at the influence of more and more uncertain factors on transmission network planning,to improve the risk resistance of transmission network,this paper proposes a risk assessment method of transmission network planning scheme and a portfolio optimization model of transmission network planning projects based on Conditional Value-at-Risk(CvaR).This paper mainly research the transmission network planning method based on CvaR from the following three aspects:(1)The concept of Conditional Value-at-Risk of Energy Not Supplied(CvarENS)is proposed to quantitatively evaluate the impact of uncertainties on power supply reliability of transmission networks.The system outage is used to describe the power supply reliability of the power system.The concept of Conditional Value-at-Risk(CvaR)which is used in the financial field to evaluate the risk of asset income is introduced to quantitatively describe the probability characteristics of the power outage caused by uncertain factors.So we get the the concept of Conditional Value-at-Risk of Energy Not Supplied(CvarENS).Compared with traditional quantitative methods,CvarENS can better describe the tail characteristics of outage distribution,more comprehensively measure the risk level of the planning power grid,and it has stronger applicability than EENS.(2)A risk assessment method of transmission network planning scheme based on CvaR is proposed,which is used to evaluate the power supply risk of transmission network planning scheme.Taking CvarENS as the risk index of risk assessment,the influence of uncertainties on power supply reliability of transmission network is quantitatively analyzed.According to the difference of risk tolerance,the power supply risk of transmission network planning scheme can be assessed in varying degrees by adjusting the confidence level,so as to control the power supply risk level of transmission network planning scheme,and to solve the limitation of traditional risk assessment methods.(3)Aiming at the problem of portfolio optimization of transmission network planning projects in the planning department of power grid company,a portfolio optimization model of transmission network planning projects based on Conditional Value-at-Risk(CvaR)is proposed.The proposed model considers the uncertainties such as power supply,power load and outage of system components.The objective of the model is to minimize the sum of outage loss based on CvarENS,annual investment cost and annual operation cost.The contradiction between investment economy and power supply risk is balanced,which makes up for the deficiency of the existing method in measuring the risk of the power supply.This method provides a scientific and reasonable method for the portfolio optimization model of transmission network planning projects.