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Abstract: This paper described the structure of a Shunt Active Power Filter system and compared various methods of active power filter harmonic detection, then the improved adaptive algorithm was used in active power filter harmonic detection; as regards the control strategy, the control method that based on optimal voltage space vector hysteresis current was presented in this paper for tracking control, And by using Matlab/Simulink simulation software, the Adaptive filter detection system and control model of Three-phase three-wire Shunt Active Power Filter were established. Simulation results showed that the selected detection method and control strategy of harmonic current played a fairly good compensation role on the harmonics which was generated by nonlinear loads and had a good dynamic compensation performance. [Copyright &y& Elsevier]

Abstract: Frequency is an important parameter of a power system, and frequency measurement is a very important link in a power system measurement device. This paper compared the accuracy of the Fourier frequency measurement algorithm with different sampling period, chose the method of whole cycle to improve. Calculated based on the empirical model and used the least error squares fitting the error compensation curve to correct the result and get a new algorithm in frequency measurement which is convenient in calculation, high precision and real-time because it need only 2 sampling cycle and does not increase the complexity. The simulation results show the frequency value measured by improved algorithm is highly accurate and can be applied in a quick arc-suppressing system. [Copyright &y& Elsevier]

Abstract: Nowadays, renewable energies have taken a special role in power systems and most of distributed generations (DGs) in power systems also utilize these types of energy resources. Their advantage, including the use of renewable energies which are not polluting environment and owning endless nature, the use of these resources to produce electrical energy in the world is increasing. A problem with such generators is the unwanted islanding phenomenon. In this paper, a new technique to detect islanding conditions has been proposed. The performance of the proposed method based on passive methods is much more appropriate than that of previous methods. The simulation results performed in MATLAB, clearly show improved operation of this method. [Copyright &y& Elsevier]