Simulation Analysis of Low Voltage Micro grid under Different Fault Conditions using Fault Models

Abstract

Microgrid, which provides a new and effective way of making full use of distributed energy, still faces numerous technical challenges [1]–[3]. Microgrid protection [4], [5] is one of them. To understand the fault features of microgrid, it is necessary to explore the fault models of IIDGs, which take the dominant position of micro-sources within a microgrid. In essence, IIDGs can be classified into PQ controlled IIDGs (PQ-IIDG) and voltage controlled ones (V/f-IIDG). PQ-IIDG injects a given power into microgrid and acts as a controlled current source. V/f-IIDG is responsible for maintaining the voltage and frequency of microgrid, so it behaves like a controlled voltage source. The key point of developing IIDGs’ fault models is to understand how they respond to abnormal conditions when fault occurs in microgrid, in other words, how their voltage or current references change. In [17], a virtual impedance based method is applied to modify the voltage references of V/f-IIDG, thus to limit the over current caused by load step; however, the cases of unbalanced faults are not taken into consideration.

                In this work, develops fault models of IIDGs within a low-voltage microgrid, including active/reactive power (PQ)-controlled IIDGs and voltage-controlled IIDGs. Voltage-controlled IIDG is of great significance on maintaining a stable microgrid. The model of voltage-controlled IIDG proposed in this work, keeps its voltage-source nature while accomplishing current limiting. The performance of the proposed IIDG fault models can be implemented in Matlab/Simulink environment.