Research of hybrid active power filter based on FBD method detection
To fast and effectively detect harmonic current of power system, FBD method is proposed. Compared with method which is based on instantaneous reactive power, FBD method has no complex transformation and transformation, it can be used to detect harmonic current for single-phase, three-phase three-wire and three-phase four-wire system. But FBD method needs a low-pass filter to extract the DC current, it causes delay and phase-shifting problems, to solve these problems, this paper presents a real-time sliding window to extract the DC current instead of low-pass filter. At the same time, shows the principle of hybrid active power filter, and corresponding mathematical model is established. Finally, take a new composite control strategy. Simulation results show correctness of the detection and effectiveness of the new composite control strategy.
Application of FBD-method to real-time current detection in three-phase four-wire system
A real-time current detection based on FBD(Fryze-Buchholz-Dpenbrock) method is pre-sented to detect the harmonic,negative-sequent and zero-sequent currents in three-phase four-wire system,and the essential of the method is the projection transformation of reference voltage.With reference voltages and currents,the equivalent conductance is acquired,and then used to calculate the instruction current,thus the current is in phase with the reference voltage.The fundamental positive-sequent active and reactive currents,unsymmetrical current and harmonic current can be detected in case of voltage distortion,which extends the application field of FBD method.Compared with the detection method based on instantaneous reactive power theory,it does not need Park transformation and d q transformation.Simulations prove its feasibility and validity.
Repetitive learning control and its application to a class of nonlinear systems
A new repetitive learning control method based on steady-state response is proposed for the tracking or rejection of unknown periodic reference or disturbance with a known period. It is essentially a feedforward approach and has the merits of high accuracy, easy implementation and insensitive to non-repetitive disturbances, compared with the conventional repetitive control method. Then the proposed method is applied to a class of nonlinear systems, where the disturbances have nonlinear dependency on the output with only continuous Lipschitz condition imposed, which can address most cases in practice. The effectiveness of the proposed method is confirmed by simulation results