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Jing L.-B.,China Three Gorges University | Jing L.-B.,Hubei Collaborative Innovation Center for Microgrid of New Energy | Zhang Y.-J.,Shanghai University
Dianji yu Kongzhi Xuebao/Electric Machines and Control

An exact analytical method for magnetic field calculation was proposed in the concentric magnetic gear with Halbach permanent-magnet arrays. The analytical method is based on the resolution of Laplace's and Poisson's equations for each sub-domain, i.e., inner and outer permanent magnet rotors, inner and outer air-gaps, and slots. The globe solution was obtained using boundary and continuity conditions. Owing to obtaining the analytical expressions of air-gap flux density, any rotor position of electromagnetic torque was calculated precisely, quickly and easily by using the Maxwell stress tensor. Compared air-gap magnetic field distributions and electromagnetic torque computed by the analytical method with those obtained from the 2-dimensional finite element method (FEM), the waveform shows good agreement with the measured waveform which proves the proposed method is correct and effective. ©, 2014, Editorial Department of Electric Machines and Control. All right reserved. Source

Cheng S.,China Three Gorges University | Cheng S.,Hubei Collaborative Innovation Center for Microgrid of New Energy | Chen M.-Y.,Chongqing University
International Journal of Electrical Power and Energy Systems

The study investigates multi-objective reactive power optimization (MORPO) of distribution system penetrated with distributed generation (DG). Integrating the reactive power of DG as one type of decision variables, a multi-objective model for RPO has been established to decrease the system active power loss, reduce voltage deviation and minimize the total capacity of reactive power compensation (RPC) devices (or minimize investments on RPC devices). Instead of converting the multiple objectives into a single one, a dynamically adaptive multi-objective particle swarm optimization (DAMOPSO) algorithm with introduction of special adaptive techniques has been proposed and validated and then applied to the MORPO problem with continuous and discrete variables. In order to the proposed MORPO model and the application of DAMOPSO, and to obtain a deep insight into MORPO with different objectives, a series of simulations on IEEE 33-bus system along with analysis and discussion are carried out. The results verified the feasibility and effectiveness of the proposed strategy. © 2014 Elsevier Inc. All rights reserved. Source

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