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In this paper, transmission lines overload alleviation for the Sudan National Grid has been performed. Resizing the transmission system components is not suitable during the operation. On the contrary, in that case, alleviation of the overloads by generation rescheduling is suitable and effective. Decreasing the generation station output relieves transmission line overload, but to maintain the power equilibrium, the output of other generation stations must be increased, making sure no additional transmission lines are being overloaded. A simple, efficient, fast, and accurate technique for the alleviation of line overloads by corrective generation rescheduling and load shedding is applied to alleviate the overloads. The method ensures that alleviation of the existing violations does not create any new violations. The load shedding is used as a last choice in cases when generation rescheduling has not completely alleviated the overloads. An overload that cannot be relieved by only rescheduling the generation is always due to weaknesses in the system design. The method gives good results for alleviating line overloads in cases of the most severe contingencies.

Linear permanent magnet (PM) machines are applicable to a number of prototype renewable energy devices and therefore are candidates for deployment. Synthetic loading for efficiency evaluation of linear PM synchronous machines is described and evaluated. Synthetic loading is a technique that eliminates the need for an external mechanical load to absorb generated shaft power during rated load efficiency tests. As such it is a technique ideally suited to the large linear PM generators proposed for renewable applications. Mathematical expressions for synthetic loading are derived for the linear PM synchronous machine using the dq machine model that includes core loss. Synthetic loading and standard efficiency tests, as methods of efficiency evaluation, are simulated using MATLAB and SIMULINK. Simulation data are verified by experiment for both the synthetic loading test and the standard efficiency test. Simulation and experimental results show that the synthetic loading method is capable of evaluating the efficiency of linear PM synchronous machine under test. The results show good agreement with standard efficiency tests. The key contribution of this work includes the mathematical expressions of synthetic loading applied to linear PM synchronous machines, the hardware and software implementation of the technique and the validation of the synthetic loading as a technique for efficiency evaluation of linear PM synchronous machines

Line Start Interior Permanent Magnet Synchronous Motors became competitors to cage induction motors in the general purpose industrial applications for their zero steady-state speed regulation, high efficiency and high power factor as well as for their ability to self-start from the regular fixed frequency supply. However, these motors suffer from parameters variation during operation due to the temperature fluctuations of the permanent magnet and saturation to the stator iron core. The paper uses the wellknown time harmonic finite element analysis to study some performance characteristics of one of these commercial motors considering these changes. Moreover, the problem of PM irreversible demagnetization due to abnormal armature reaction is studied for the same motor.