A simplified shunt APF model based on instantaneous energy equilibrium and its application in DC voltage control

Suitable model for the analysis and control of the shunt active power filter (APF) was quite difficult to obtain, which prohibited not only the industrial applications, as no generalized method to design the control loop, also the analysis and comparison between existing control methods. In this paper, a simplified shunt APF model, including the steady state model and small signal model, based on the instantaneous energy equilibrium is proposed. Subsequently, the newly built model is used to analyze two popular control methods in detail, as the shunt APF control with or without the reactive and harmonic current detection, in the DC voltage control loop responses to different load current disturbances. The obtained results are compared with the time domain simulation results for the control method with the reactive and harmonic current detection, the differences for them are found as the time delay caused by the low path filter (LPF) in the detection, the control and the whole system model is improved by considering this effect, and the comparisons on the responses to different current disturbances are evaluated for these two control methods accordingly. Finally, an example of the shunt APF control loop design is done based on the new model in the control method without reactive and harmonic current detection, the computer simulation and the prototype experiment are done to verify the validity of this newly designed compensator accordingly.