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The air-cooled turbo-generator often works in the more frequent start-up and shut-down operation. Either the misoperation or the failure of synchronizing controllers can cause the out of phase synchronization fault. The fault can disturb the power angle and cause a strong impact electromagnetic force for the generator. With the traditional numerical calculation method, it is difficult to calculate the variations of key physical parameters and the electromagnetic field in the end region of the generator under complex working conditions, especially the out of phase synchronization fault. In order to solve the problem, a calculation method of the nonlinear transient electromagnetic field with multi-domain field-circuit-grid coupled is proposed. The correctness of the model and method is validated by comparing the calculated and test values of the magnetic density flux at the key points of the generator under the no-load condition. Based on this method, the power angle variation, the magnetic flux leakage distribution in the end region, and the electromagnetic force on the end winding in the transient process of the fault are calculated and analyzed. [ABSTRACT FROM AUTHOR]

The 120° voltage source inverter driven brushless dc (BLDC) motors are very common in many applications. This paper extends the previous work and presents an improved dynamic average-value model for such BLDC motor-drive systems. The new model is explicit and uses a proper qd model of the permanent magnet synchronous machine with nonsinusoidal rotor flux. The model utilizes multiple reference frame theory to properly include the back EMF harmonics as well as commutation and conduction intervals into the averaged voltage and torque relationships. The commutation angle is readily obtained from the detailed simulation. The proposed model is demonstrated on a typical industrial BLDC motor with trapezoidal back EMF waveforms. The results of studies are compared with experimental measurements as well as previously established models, whereas the new model is shown to provide appreciable improvement. [ABSTRACT FROM PUBLISHER]

Directly coupled electromagnetic field-electric circuit modeling approach for coupling an electrical machine to its associated external circuit and power electronics has been widely reported in the literature. However, the inclusion of a closed-loop control system, such as conventional vector (field-oriented) control, within a directly coupled electromagnetic field-electric circuit model has not been widely studied. This is partly because it is a rather complex task. This paper introduces a directly coupled electromagnetic field-electric circuit computational model in which a conventional vector control system has been incorporated for detail simulation of vector-controlled electric machinery drive systems. The model has been successfully applied in the design and analysis of a vector-controlled wound field brushless starter-generator system prototype. Comparison between the simulation and test results for both motor and generator modes show excellent correlation that validates the efficacy and computational soundness of the modeling approach. [ABSTRACT FROM AUTHOR]

This paper presents an exhaustive simulation study performed to validate the adequacy of the equivalencing method promoted by the National Renewable Energy Laboratory for modeling wind power plants by single- and multiple-machine equivalents. The main simulation results are presented for a number of steady state and transient wind turbine generator operating conditions following various faults and a typical low-voltage ride through. The impact of protection systems such as the crowbar is also taken into account. The aggregation technique has shown to be adequate for load flow, stability, and electromagnetic transient studies with limitations, as presented in the paper. [ABSTRACT FROM AUTHOR]

In this paper, applying field orientation based on particle swarm optimization (PSO) controls the speed of two- asymmetrical-winding induction motor. The maximum efficiency of the motor is obtained by the evaluation of optimal rotor flux at any operating point. In addition, the electromagnetic torque is also improved while maintaining a fast dynamic response. In this research, a novel approach is used to evaluate the optimal rotor flux level. This approach is based on PSO. This research presents two speed control strategies. These are field-oriented controller (FOC) and FOC based on PSO. The strategies are implemented mathematically and experimentally. The simulation and experimental results have demonstrated that the FOC based on PSO method saves more energy than the conventional FOC method. [ABSTRACT FROM AUTHOR]