Interaction Between Micro-Grid Generators and Active Front End Converters: Modeling, Analysis and Solutions

This paper presents modeling and analysis of a field issue having system interaction between a Micro-Grid Generator (MGG) connected to an Adjustable Speed Drive (ASD) utilizing an Active Front End (AFE) converter. In a MGG - AFE system, MGG terminal voltage harmonics are typically of low magnitude, but some select harmonic frequencies can resonate and be amplified by interacting with the AFE system's LCL filter resonant frequency point, resulting in excessive high frequency ac line oscillations. Interesting, the same AFE - LCL filter system connected to the utility grid displayed no such resonance issue. Reasons for this behavior are discussed in the paper. A post-sale passive filter solution that can be applied to solve the MGG - ASD resonance problem is proposed and analyzed with simulation and experimental results. A summary checklist of steps to investigate to avoid resonance issues for MGG - AFE systems is provided.