Local and Distributed Voltage Control Algorithms in Distribution Networks

In this paper, we consider a voltage control problem in power distribution grids. The specific goal is that of keeping the voltages within preassigned operating limits by commanding the reactive power output of the microgenerators connected to the grid. We propose three strategies. The first two strategies are purely local, meaning that each microgenerator updates the amount of reactive power to be injected based only on local measurements of the voltages' magnitude. Instead the third one is distributed, namely, the microgenerators, to perform the updating steps, require some additional information coming from the neighboring agents. The local strategies are simpler to be implemented, but they might fail in solving the voltage control problem. Instead, the distributed one requires the microgenerators to be endowed with communication capabilities, but it is effective in driving the voltages within the admissible intervals and, additionally, it exploits the cooperation among the agents to reach also a power losses minimization objective. Theoretical analysis and extensive numerical simulations are provided to confirm the arguments aforementioned.