Demonstrating the effectiveness of active voltage control technologies in congested low-voltage distribution networks

The electricity network consists of high-voltage transmission and medium- to low-voltage (LV) distribution systems. Transmission is looped and easily controlled, while distribution is radial, vulnerable to outages, and lacks remote operation capability except for limited interventions. Real-time data from distribution is rare. Traditional grid design was functionally adequate until the rise of many solar and small power plants. To meet climate goals, the network must accommodate renewable energy production, requiring adjustments beyond voltage drop considerations to handle voltage fluctuations. As part of an innovation project, a Hungarian DSO has installed in-line voltage regulator (IVR) and on-load tap changer transformer (OLTC) units in more than 20 LV network locations, with the aim to demonstrate their effectiveness in voltage control. During the pilot, a measurement campaign was also conducted to properly assess the effects of these units on power quality and the fluctuation of the voltages. In our paper the detailed results of these pilots are presented, focusing not only on the numerical results concerning the decrease of voltage variations, but also providing insight to operational experiences. Finally, the best practices are presented on how the LV supply areas should be selected to maximise the technical capabilities of IVR and OLTC units.