Optimal placement of multiperiodbased switched capacitor in radial distribution systems Abstract   This paper proposes a methodology for optimal allocation of multiperiodbased switchable capacitor in radial distribution systems to minimize the energy loss and improve the voltage profile. In the proposed methodology, each monthly typical day is divided to numerous time segments under a socalled number of segments (NOS) factor. Several possible values of NOS are evaluated to seek its impact on systemu0027s yearly loss. In the optimization process, by considering a common value of NOS, an optimal candidate bus for locating capacitor is obtained while the capacitor step is optimized in each segment. To speed up the solving process, a technical constraint is offered to ignore the nonimportant states for capacitor size evaluation. Moreover, two methods for load flow calculations including the direct load flow and backwardforward sweep methods are investigated. The proposed methodology is applied to IEEE 10bus, 33bus, 69bus, and 85bus systems, and thereby relevant conclusions are drawn.

Optimal Operation of Active Distribution Network Involving the Unbalance and Harmonic Compensation of Converter The massive accessing of unbalance and nonlinear loads to a power distribution network may cause serious problems on power quality and result in additional power loss and safety risks. Distributed generation (DG) with a converter interface has a flexible adjusting ability and can provide certain unbalance and harmonic compensations to power distribution networks. In this study, an optimal operation method of an active distribution network (ADN) involving the unbalance and harmonic compensation of a converter was proposed. First, the power regulating characteristics of DG were analyzed. Second, an optimization model was constructed to minimize ADN power loss, sum of harmonic voltage squares, and total unbalance of the negative sequence voltage, and multiple constraints, such as converters and network, were considered in the model. Third, the optimization model was transformed into a semidefinite programming model based on the characteristics of the nonconvex and nonlinear original model, thus assuring global convergence and decreasing difficulties in problem solving. Finally, the validity of the proposed algorithm was verified by using IEEE 33node and 123node test systems.