Study On The Practical Application Of Optimal Power Flow Based On Linear Programming

Based on the Linear Programming (LP) technique, the problems of Optimal Power Flow (OPF) are studied thoroughly from the viewpoint of practical application in this thesis. The main contents and contributions are as follows:(1) Based on the Nonlinear Programming (NLP) model of OPF, the mathematical formulation of the LP-based OPF is constructed and the flowchart for its application is described in detail.(2) As the fundamental of the LP-based OPF, the calculation of sensitivity coefficient is discussed in detail with three methods, i.e. the Jacobian matrix inversion method, the control variable perturbation method and the Jacobian matrix direct-conversion method. Some improvements are made on the Jacobian matrix direct-conversion method and its application is expanded from the reactive power optimization to the general OPF. In terms of the perturbation method, it is found that the calculation result is very sensitive to the evaluation of the perturbation of the control variables.(3) Concerning the characteristic of the power system and the request of the linear programming, it is needed to select the active constraints which should be enforced in the LP.(4) For the different reasons of network constraints violation, a systematic approach is established. It is found that the linear approximation would make the operating point away from the feasible region and the selection of the constraints would expand the feasible region.(5) For the different reasons of objective's increasing, the corresponding measures are given. It is shown that the operating point moves in two ways when the objective goes in the opposite direction. Some control variables which would make the objective increase should be selected to adjust the step size.(6) According to the trust region method, it is suggested that the step size should be adjusted to accelerate the convergence rate.The proposed method is illustrated on the WSCC 9-bus test system, IEEE 30-bus test system, IEEE118-bus test system and a certain Chinese regional 109-bus real system, respectively. The simulation results show that the proposed method is correct and effective.