Risk Management In Transmission System Planning, Cost Evaluation And Depreciation Issues

There are many subjective and objective risk factors in the long period from transmission system planning to decommissioning and/or disposal of electric assets, such as risk preferences of decision-makers in network planning, design changes and schedule delays in engineering construction, which will affect investment returns and operating efficiency. Given this background, in order to improve investment returns and operating efficiency, it is vital to manage risks in the whole process from network planning to decommissioning and/or disposal of assets. At present, existing problems in transmission system risk management include several aspects:1) the study of transmission system risk management is still preliminary and not systematic; 2) risk preferences of decision-makers is not comprehensively considered in network planning; 3) quantitive methods are still not well developed for the cost risk management; 4) policy risk should be examined in a systematic way.In view of the above issues, in-depth research is performed in the following aspects, with respect to the situation and characteristics of transmission system risk management at home and abroad.(1) In view of the problems existing in risk management of transmission system, a life cycle based analytical framework for risk management is put forward, and some other suggestions of risk management are put forword in period of network planning, engineering construction and operation, in order to provide the reference for further development of transmission system risk management.(2) In order to introduce risk preferences of decision-makers into the evaluation of power network planning schemes, a new method with utility function is presented. First, the relevance among evaluation indexes of the same type in power network planning decision-making is removed by using a new comprehensive evaluation method based on the Choquet capacity and integral. Then, An appropriate utility function is used to describe the risk preferences that various decision-makers may have in addressing the uncertainties of profit. After that, the Choquet integral based risk premium is employed to measure the reduced part of the profit and the result of subjective expected comprehensive profit can be obtained and employed as the result of the comprehensive evaluation of economic indexes. Finally, a decision-making reference table is established based on economic and reliability indexes.(3) A new method of evaluating transmission project cost and risk control with value at risk (VaR) is proposed in order to make the evaluation quantitative. First, the total cost of a transmission project is first broken into a number of independent unit subproject costs. These unit subproject costs are evaluated by using the weight analysis method based on Value at Risk (VaR) and the main unit subproject costs are identified. Then, considering the interval constraints of the values of uncertain factors, a stochastic linear programming model is established with an objective to control the cost within a given risk range. Finally, the Monte Carlo simulation is used to sample the random factors and then a definite linear programming problem can be attained and solved.(4) In the background of electricity tariff reform, the way of enterprise earnings changed into cost-plus-benefit model. In this new model, depreciation will both affect the benefit and cost, and it becomes much more complicated that depreciation impacts on the profit of grid enterprises. First, this thesis reviews depreciation of fixed assets, government policies and equipment life. Then, the impacts on the profit of grid enterprises with depreciation life changes are studied. Finally, the net curve of depreciation in advance is calculated, and power grid assets depreciation policy suggestions are proposed.Finally, several conclusions are obtained based on the research outcomes, and directions for future research indicated.