A case study of using OLTC to mitigate overvoltage in a rural european low voltage network

Increasing penetration of distributed renewable energy sources such as PV may lead to voltage rise in the LV distribution networks. When local production exceeds local consumption, this voltage rise may lead to overvoltage, i.e. violation of the EN 50160 standard. A number of solutions have been developed to mitigate the over voltage, thus increasing the hosting capacity of the LV network without violating EN 50160. Equipping a distribution transformer with On-Load Tap Changer (OLTC), can also solve the overvoltage problem in the LV network. A challenge for the OLTC control is to deal with different voltage profiles of downstream lines of the LV network. This paper evaluates a classical OLTC-based control to mitigate the overvoltage problem and analyzes the possible voltage violation at downstream of the LV network in a rural European LV network.1