The Influence of Shunt Active Power Filter on Stability and Performance in Considering Time-Delay

摘要

The existence of time-delay in active power filter (APF) has a great influence on its stability and performance. Hence, this paper deals with the problems of solving the delay margin, the maximal delay which allows the closed-loop system to retain stable, and minimizing the performance index for a given H_∞ controller. Firstly, for the given time-delay system and controller, a Lyapunov-Krasovskii functional is used to derive a delay-dependent stability criterion. And a modified Lyapunov-Krasovskii functional is used to obtain less conservative results. Secondly, the mathematical model of APF with time-delay is built, and the two problems already mentioned can be dealt with via transforming them into one of the basic problems of linear matrix inequality (LMI). Finally, the relationships between the delay stability margin and some parameters have been investigated, and the performance index has been discussed in considering time-delay. The effectiveness of the proposed method is verified by simulation studies.