Grid-connected Response Verification of AC Microgrid under Single Line-to-ground Short Circuit

Abstract

In design of power systems, assumptions are made to model the physical systems. The assumptions may not sufficiently reflect the behavior of the system under normal and faulted conditions. Under short circuit conditions, system parameters vary significantly, particularly in microgrids with grid interconnection capabilities. This paper presents the result of validating the response of a microgrid which is capable of grid interconnection and islanding under voltage and reactive power control regimes. The microgrid is modeled to incorporate two wind turbines, each rated 5.5 kW, 400 V. The utility has synchronous generator rated 100 MW, 13.8 kV. Both the utility and microgrid are capable of exchanging active power and reactive power. Single line-to-ground short circuits are introduced and withdrawn at 30.00 s and 32.00 s, respectively. The dynamic responses of the testbed are captured pre-, during- and post-short circuit in grid-connected mode under both control regimes. The response of the testbed is verified to be consistent with established short circuit theory, verifying the validity of the system for short circuit detection and analysis. The testbed can therefore be used for short circuit and related studies, design optimization and power system performance prediction.