Cordination Optimization Dispatch And Its Evaluation In Wind Integrated Power Systems

At present, open and impartial dispatching is still the main dispatching mode inChina. Its fundamental requirement is to make the difference in the completion ratio ofeach generation plant’s annual contract volume as small as possible on conditions thatmeeting the electric power and energy balance and other constraints. Besides, in order tomake sure the fairness of annual contract and protect all generation plants’ interest,annual generation utilization hours of each units are allocated on average according tothe installed capacity. Because not considering the difference of generation units in theenergy consumption and emissions, this dispatching mode leads to the waste of resourcesand pollution. With resource and environment problems paid more and more attention,wind integration, energy saving and emission reduction are inevitable trend. Solong-term optimization dispatch in wind integrated power system must take intoconsideration many inconsistent factors such as energy saving, environment friendly,fairness, security, wind utilization and so on. On the other hand, in order to cope with theuncertainties of wind power, generation units and load, the power system must reservesome generation capacity to ensure the reliability of power system. In general, the morespinning reserve, the more reliable power system will operate. But with the increase inthe spinning reserve, marginal benefit of the spinning reserve decreases. Therefore, wemust determine the optimal reserve to make the best of the total benefits of economy andreliability.According to different dispatching principle, different dispatching mode can beestablished. The goal of economic dispatching mode is to minimize the total generationcost; Environmental economic dispatching mode takes into account both the economicand environmental benefits; while the goal of open and impartial dispatching mode is tomake the difference in the completion ratio of each generation plant’s annual contract volume as small as possible. The actual dispatching mode depends on which goals thedecision maker lays particular stress on. In order to facilitate comparative analysis of thegeneration scheduling, it’s necessary to evaluate each scheduling.Based on the above background, this paper mainly carry out the following researchwork:(1) Firstly, the variety law of wind speed is modeled by two-parameter Weibulldistribution; Then on the basis of comprehensive consideration of coal consumption,emissions, openness and impartiality, a long-term multi-objective fuzzy optimizationdispatch model is established. After piecewise linearization of the objectives and theconstraints, the optimization model is converted to a mixed integer linearprogramming(MILP) problem. An efficient optimization software CPLEX is employed tosolve the problem.(2) On condition that wind power and load forecast errors followGaussian distribution with mean zero, and the operation states of generation units aredescribed by two-state Markov model, EENS calculation model is obtained. Thenaccordingly an optimization model including generation cost, social cost of loadshedding and reserve cost is built to solve the spinning reserve of maximizing the socialbenefit.(3) In order to analyze and compare different generation scheduling, a series ofindices and fuzzy comprehensive evaluation method is utilized to evaluate the optimalgeneration scheduling obtained.