Research On Transmission System Planning Based On Uncertainty Theory

Large-scale renewable energy penetration,application of demand side management and complicated environment brings many complex uncertainties to the power system.Therefore,transmission system planning faces severe challenges,such as how to model the uncertainties and how to consider the uncertainties in the planning model.In this dissertation,models of uncertainties are established and transmission system planning models which are suitable for the different scenarios and satisfy various requests are proposed based on the uncertainty theory.The achievements perfect the transmission system planning methodology considering uncertainties.The primarily work and achievements of this dissertation are as follows.(1)The transmission system planning method considering the correlations among wind power and dependencies among the nodal load prediction is proposed.Firstly,the Johnson system is used to describe the probability distribution of multi-dimensional uncertainties.Secondly,the planning model is established,which minimizes the investment cost of the planning scheme and is constrained by the limit of branch power flow,load prediction correlation and wind power correlation.The combination of Sobol's sequence generator based Monte Carolo simulation and quantum inspired binary particle swarm optimization(QBPSO)method is adopted to solve the planning models.(2)An adjustable robust transmission system planning method considering load prediction correlation is put forward.The load prediction is described by the interval number.According to the adjustable robust optimization theory,an adjustable robust optimization model for minimal load curtailment is propsed considering correlation among the interval load and is employed to be the security indicator of the planning scheme.On that basis,a bilevel transmission system planning model considering correlation among interval load is proposed.The security and economy of the planning model is coordinated by adjusting the robust parameter.(3)The transmission system planning method considering probability models of wind power and interval models of load prediction is presented.The objective of the planning model is the minimization of investment cost and the model is constrained by the limit of branch power flow under the stochastic wind power and interval load.The combination of the Sobol's sequence and the improved branch-and-bound algorithm is used to validate the security of the planning scheme and the QBPSO is employed to optimize the planning model.(4)A transmission system planning method considering probability model of wind power and fuzzy model of load prediction is put forward.Probability model of wind power and fuzzy model of load prediction are expanded to fuzzy-random models.The planning model,which minimizes the investment cost,is constrained by fuzzy-random chance constraint of branch power.By taking advantage of the properties of the proposed planning model,the fuzzy-random chance constrained model is transferred to the planning model considering interval model of the predictive load and probability model of the wind power.As a result,the comuputational efficiency is improved.(5)A multi-stage transmission system planning method considering fuzzy model of predictive load and interval model of wind power is proposed.The multi-stage transmission system planning model considering fuzzy uncertainty and interval uncertainty,minimizing the the investment cost and subjecting to fuzzy chance constraint of branch power is constructed.The multi-stage planning model is transferred to multi-stage robust planning model according to the property of the planning model.Thus,the computation burden of solving the planning model can be decreased.(6)A probabilistic-interval reliability evaluation method is presented.In the light of probability model of wind power and interval model of load prediction,the conception and the computation method of probabilistic-interval reliability evaluation are proposed.This indicator allows the planners to deeply understand the reliability of the planning schemes.Analyses on a typical 24-bus system and a real 231-bus system verify the feasibility,validity and applicability of the research contents in this dissertation.