A two-layer control strategy for voltage regulation of active unbalanced LV distribution networks

Abstract

In this paper, a coordinated control strategy is proposed to effectively address the voltage regulation issue in active unbalanced low-voltage (LV) distribution networks. The proposed control scheme is based on a two-layer centralized approach, consisting of the local and the overlaying control layers. The former is embedded at the hardware level of the distributed renewable energy sources (DRESs). Therefore, it is continuously active, aiming to prevent network overvoltages and to mitigate voltage unbalances based explicitly on local measurements. The overlaying control strategy is implemented at a central controller, at the distribution system operator (DSO) level, acting supplementary to the local control scheme to increase the total injected green energy and to implement DSO policies for the reallocation of the active power curtailment. The validity of the proposed two-layer control strategy is demonstrated on a real Slovenian LV network by means of time-series simulations. Additionally, the impact of the proposed control on the maximum DRESs penetration level is thoroughly evaluated, while its performance is compared against other conventional control strategies, revealing its superiority in terms of voltage regulation, voltage unbalance mitigation and increased green energy production.