Optimal Allocation Of Intermittent Distributed Generation And Reactive Power Compensation Based On Bilevel Programming

Under pressure of the severe situation of energy and environment for humansurvival, all the countries in the world regard the exploitation of renewable energysources as the future energy development strategy. The wind and solar energy havereceived a lot of public attention by resort to the particular advantage of substantialresource, without regionality and cleanness. With the advancement of technology andimpulse of policy, the intermittent DGs (distributed generation) which represented byDWG (distributed wind generation) system and PV (solar photovoltaic generation)system obtained a rapid development. The practice has demonstrated that to optimizethe location and capacity of intermittent DGs would be propitious to improve thevoltage quality, system load rate and reduce the network power loss.Based on the study of probability model of intermittent DGs’ output power andload power, this paper proposes an analytical algorithm of probabilistic power flowbased on semi-invariant and Gram-Charlier expansion. Taking the effect of economicbenefit of dynamic reactive power optimization of distribution network whichcontains intermittent DGs into consideration, the dynamic reactive poweroptimization model of distribution network which contains intermittent DGs isestablished. And genetic algorithm with elitist strategy is used for the optimal solution.Result of example has indicated that time variation of system load power andintermittent DGs’ output power would affect the economic benefit of dynamic reactivepower optimization of distribution network. Thereinto, the intermittent DGs’ outputreactive power can upgrade the reactive compensation reserve capacity of distributionsystem and ease the pressure of Cs’(compensation capacitor) reactive compensation.Accordingly, the effect of system dynamic reactive power optimization is improved,the fluctuating of system node voltage is reduced and the probability of voltageamplitude within the normal range is enhanced.Concerning the intermittence and random fluctuating of intermittent DGs’ outputpower, with application of opportunity-constrained programming method whichapplies to the uncertain environment, aiming at taking account of economic benefit ofsystem programming and voltage quality, the bilevel optimal allocation model ofintermittent DGs and Cs is constructed in this paper. The lower level programmingsimulates the dynamic reactive power optimization of distribution network to determine the optimized operational yearly expected benefit of C. In order todetermine the optimal allocation scheme of intermittent DGs and Cs, the upper levelprogramming has taken the static programming economic benefit of intermittent DGsand Cs and optimized operational yearly expected benefit of C into comprehensiveconsideration. And then genetic algorithm with elitist strategy is used for the optimalsolution. With using the probabilistic power flow calculation results to put upprobability verify for the chance constrained, the simulation example shows thatoptimized operational benefit of C would affect the optimal allocation of DGs and Cs,and it would be remarkably influenced by Cs’ capacity, maximum daily allowablenumber of switching operations, seasonal change of the expectation of DGs’ outputpower and load power. In addition, despite increasing the cost of investment, raisingthe configuration capacity of Cs can enhance the optimzied operational benefit of Cand system voltage quality. While transforming the optimized operational benefit of Cinto optimized operational yearly expected benefit of C, the method of dividing timecan be used to unify the time scale of bilevel programming.