Optimal Reactive Power Flow Based On IPM And ACA

With the increasing of power capacity and electric equipment,the requirement of reactive power grows day by day.The unbalanced reactive power will cause the drop of power factor and voltage,the decline of capability of network transmission,and the increase of active power loss,so the equipments can not be sufficiently utilized,even be damaged.The reactive power optimization is an efficient method to guarantee the system's security and economically running and an important approach of decreasing the active power loss and enhancing the voltage quality,so it has the all-important theoretical value and practical significance .About the optimization methods,the advantages of primal-dual interior point method are that counting time has little relation with the size of problem and counting time doesn't follow the increase of the size of problem to rise distinct.The method's disadvantage is that the discrete variables can't be solved in primal-dual interior point method.Ant Colony Algorithm is a new developed bionic optimization algorithm,which simulates the ants'finding food process.Because of its simple mechanism,plus-feedback parallelization,strong lustiness and excellent distributed computational mechanism,it has shown huge developing potential in solving many complicated optimization problems.In this thesis,by integrating an ant colony optimization algorithm (ACA) with an interior point method (IPM), a hybrid strategy for the optimal reactive power flow (ORPF) problem is proposed in this paper.First,the original ORPF problem is converted to a continuous non-linear programming problem by relaxing the discrete variables,and the initial solution is obtained by the IPM.Then according to the discrete feature of the control variables,the original ORPF problem is decomposed into a continuous optimization sub-problem and a discrete optimization sub-problem,which are solved by IPM and ACA respectively.By solving the two sub-problems alternately,the optimal solution of the ORPF problem can be obtained.IPM and ACA take advantage of each other,so that the efficiency of the hybrid strategy is greatly improved.Furthemore,the numerical example of IEEE 6-bus and IEEE 30-bus system is employed to validate correctness and effectiveness of the proposed algorithm,and the result based on this algorithm is compared with that based on IPM and GA.