Smart resistor: Dynamic stabilization of constant power loads in DC microgrids with high bandwidth power converters and energy storage

Abstract

Power Electronic converters and electric motor drives have found increased application in automobiles, ships and microgrids. These devices when driving loads in a regulated fashion act as Constant Power Loads (CPLs). CPLs can be power converters, each regulating input current to maintain a constant output power. These converters can cause destabilizing effects on the grid due to their nonlinear behavior. This paper studies the effect of CPLs on DC Microgrids and analyzes their stability. It also demonstrates a method to dynamically stabilize these loads locally by converting them into a smart resistor using high bandwidth power converters and energy storage units. The bandwidth offered by this circuit enables the DC Microgrid to locally control any instabilities on the grid. The proposed method decentralizes the control effort making the microgrid more intelligent and reliable. Analysis is verified using simulation tools and validated using a hardware test setup.