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.
Kinemamtic analysis of flying-saw vehicle
The paper analyzes the kinematic motion of the flying-saw vehicle.After the analysis,it is concluded that the ac- celerating periods and decelerating periods in both forward and backward directions will follow sin~2αcurve and,in order to increase the sawing dimensional accuracy,flying-saw vehicle must come back as soon as possible while acceleration remains constant.Based on this premise,the paper gives out the equations of kinematic motion of the flying-saw vehicle in every sta- ges and one example result in a common situation.By now this method has been used in the real situation.