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AbstractThe three-phase shunt active power filter eliminates harmonic currents and compensates reactive power for non-linear loads. A current control scheme based on the time-domain approach for three-phase shunt active power filters is analysed in this paper. A basic outline and evaluation of the performance of existing current control methods for active power filters are presented. According to different complicated power quality issues and various compensation requirements, a current control scheme based on time domain approach is proposed. Comparing with existing methods this algorithm has very short response time delay. Different compensation current references can thus be accurately and easily obtained by adopting the proposed current control scheme. The simulation results show the excellent performance and effectiveness of the proposed method.

Exact phase plane analysis of nonlinear system containing two-position relay element, with hysteresis under the consideration of Coulomb friction, is given. Expressions for period and amplitude of stable limit cycle are derived. The effect of Coulomb friction on limit cycle behaviour is also discussed.