Modeling of Variable Switching Frequency Controlled STATCOMs and Active Filters

Abstract

This paper introduces an average circuit model for switch mode shunt converters coupled with power systems such as active filters (AF) and static compensators (STATCOM). These devices absorb or deliver reactive power to the utility network by employing a variable switching frequency modulation scheme (e.g. hysteresis current control). Analysis and simulation of these exact devices could be complex under transient and steady state conditions. Here the variable switching frequency shunt devices are modeled using an averaging approach, deriving averaged mathematical and circuit models. Further, the ripple is approximated to provide a correction to the average model. The resulting models produce much faster simulations than their exact devices. Theoretical considerations show that the averaged model agree well with the original system, and this is confirmed by PSpice and MATLAB simulations, as well as experimental results.