High-Frequency Grid Current Control of Parallel Inverters

Abstract

In high power applications such as wind energy systems, smart transformers and active power filters, parallel inverters are usually utilized in order to obtain high control bandwidths for achieving low harmonic distortion or for providing grid services. This paper provides analysis of the maximum frequency of the current that can be injected by parallel neutralpoint clamped (NPC) inverters based on proportional resonant control without facing stability problems. A lead compensation is proposed to increase the control bandwidth for improved harmonic control and for a wide frequency range, which can be controlled by the parallel inverter system. The analysis is validated by simulations and experiments.