Modeling and Transient Behavior Analysis of an Inverter-based Microgrid

Abstract

Microgrids can provide a more reliable power supply and can enable the interconnection of renewable energy. The microgrid has been recognized as one of the most important directions of power systems. The transient characteristics of the microgrid are very important for the planning and operation of the whole power system. However, its mechanism still needs further exploration because the circuit structure, control feature, and even the operation mode of the microgrid are quite different from those of the traditional power system. In this article, a dynamic model is proposed for a microgrid according to the difference in transient processes between the microgrid and the traditional grid. The model is expressed as a differential-algebraic equation system, so the structure of the microgrid and the physical meaning of original variables are preserved. The focal point in this article is the fast control function of the inverter and the strong coupling between inverter and grid. The inverter is modeled in greater detail and is similar to the structure and consistent interface of the synchronous generator model. The model is verified by simulation using PSCAD/EMTDC (Manitoba HVDC Research Centre, Canada), and the transient dynamics of microgrid are numerically and analytically studied.

Keywords:

• microgrid
• inverter model
• distributed generator
• differential-algebraic equation
• transient dynamics