Transient Stability of Low Voltage Micro Grid

Abstract

The micro grids (MG) is an essential part of smart grids, since distributed generations based on renewable energy sources are becoming incredibly popular. For low-voltage micro grid, this popularity becomes transparently obvious. In a low-voltage MG islanded mode operation, the type 4 wind turbine generators, connecting to grid through the inverter, are less sensitive to the frequency change of the MG. So it will affect the transient stability of the grid. The presence of photovoltaic generations (PV) in grid-forming and grid-feeding mode, when the frequency of the system changes, also affects the frequency recovery back to the rated value. The low-voltage MGs are commonly in radial network structure. A short circuit on the distribution line will led to line tripping and load shedding on its own. This is different from the loop transmission grid, after cutting the faulted distribution line, the system load does not change. In case of load changes, it is necessary to pay attention to the operation of the governors in order to bring the frequency back to normal. Therefore, the transient period needs to be studied for a longer time. With the above notes, the paper shall implement the transient stability survey of low-voltage MG in case of occurring disturbances such as short-circuit, load-shedding, power source loss, and also study the factors affecting transient stability. The study was conducted on ETAP software 12.6.