Control strategies on islanded low-voltage microgrids (Master/slave and droop control : study and comparison)

Distributed generation appears as the eco-friendly solution to a growing demand of electricity. Within the same idea, microgrids have become one of the most attractive sources of attention since they integrate local supply sources both with cleanliness and robustness. These microgrids can operate either connected to the utility grid, or on their own, namely the islanded mode. As it is the case for conventional grids, they need to be controlled, allowing electrical load and supply management on one hand, synchronisation with the main grid on the other. Different diversified methods of control have emerged over the last years, each suited to specific applications. This paper aims to take a closer look at numerous existing solutions by analysing their working principle and ensured functions into the grid. Further on, two of them are selected for a deeper analysis of their features: the Master/Slave control strategy and droop control. The major difference dissociating the control methods is the use of communications links in the first case, enabling smart power sharing, but implying communication delays and low expandability, while the second is based on local control and allows more precise regulation. Both control strategies are implemented on a proposed microgird benchmark. Each case demonstrates, as per expected, fundamentally different behaviours and reactions to robustness testing experiments conducted on SIMULINK simulation software; an observation section has been established so as to compare each of them. The idea is to determine the pros and cons of each and figure some general guidelines clarifying which method of control is best suited for some basic layouts of microgrid.