Multi-objective Transmission Expansion Planning In The Power Market

The transmission planning in the power market environment is established on the basis of power market, which involves the variation of the planning maker. It aims to make a reasonable transmission expansion to satisfy the inceased power load in future and the requests of market operation, and to maintain proper benefits of all the market participants and the fair market competition. Established in multi-objective transmission planning approach, this dissertion emphasis on handling challenges for transmission planning to adapt the market environment, which include transmission congestion, risks in line overloading, transmission investment profit, risks in transmission investment and solving algorithm for new models. The corresponding means of settlement are presented by proposing new multi-objective planning models. The main returns and innocations of this dissertion are as follows:1) An improved Strength Pareto Evolutionary Algorithm (SPEA) is proposed and applied in the multi-objective transmission planning. An"isolated nodes absorbing"method for initialization is presented to make all nodes in initial network connected; A reverseorder initialization method is presented to effectively decrease the line redundance. Concerning the"N"and the"N-1"principle, a"borderline search strategy"is adopted and developed to keep the optimal search process within the feasible domain. Those improvements above improve the variety of the initial population and the distribution of the Pareto optimal solution set and effectively accelerate the search process.2) A novel multi-objective transmission planning model considering transmission congestion is proposed. An index of congestion surplus is presented to describe the transmission congestion degree. And a ranking method based on"the virtual optimal solution"is presented as a reference of decision-making in the Pareto optimal set. With three objectives i.e. yearly congestion surplus, transmission investment cost and cost of power outage, the multi-objective transmission planning model is presented to achieve a planning approach which simultaneously considers transmission congestion and economy and reliability of planning schemes. 3) A novel multi-objective transmission planning approach that considers line overloading risks is proposed. A standard expected value model for multi-objective multi-stage transmission planning is presented to realize the transmission optimal planning with the control of line overloading risks. In this model, a constraint of overloading risks is built with expected value and standard deviation of random line active power and two objectives are given as expected value of the average power loss and discount value of the investment cost. By modeling uncertain informations with probability theory, the probabilistic DC power flow is adopted for the correlated calculations among random variables in the planning model.4) A novel multi-objective transmission planning approach that considers transmission investment profit is proposed. Requests for transmission investment profit and social welfare are involved in the proposed planning approach. A flexible costrecovering mechanism for transmission fixed cost is setup with a marginal cost transmission pricing model which takes account of the transmission charge rate. Afterthat, a multi-objective transmission planning model is setup for optimal planning with three objectives i.e. rate of return on transmission investment cost, social welfare and transmission investment.5) A novel multi-objective transmission planning approach that considers transmission investment risk is proposed. The Value at Risk (VaR) index is adopted to evaluate the transmission investment risk. This quantized VaR risk evaluation index can be used to effectively evaluate and control the investment risk and enhance transmission investment incentives. In the analysis of risk, the uncertainty of nodal power is taken as a random disturb and caused by which, the random distribution of transmission investment profit is obtained by solving the probabilistic optimal power flow(P-OPF). After the VaR index is adopted in objective functions and limitation of rate of return on transmission investment is taken as one of constraits, the multi-objective transmission planning model is built up to achieve the optimal transmission planning.Analysis and comprarision on the 18-bus system and the 77-bus system proves the feasibility, effectivity and practicability of the proposed planning models and solving algorithm in this dissertion.