Photovoltaic Systems Integration using On Load Tap Change Transformers for High Penetration Mitigation Issues: Case Study Malta, Europe

Photovoltaic systems (PVs) installations have gained considerable momentum in
low voltage (LV) network integration throughout the years due to their economy of scales.
Nowadays, PVs offer promising decentralized solutions towards the decarbonisation of
electrical power generation and renewable energy. However, high penetration of PVs on LV
networks brings about technical challenges mainly associated with supply voltage and network
utilisation factors. The main aim of this paper is to propose a mitigation strategy towards
voltage challenges based on real LV feeder consisting of 52 potential prosumers. A stochastic
methodology uses a Monte Carlo simulation approach and evaluates the downstream and
upstream scenarios of PV penetration along the LV feeder. On load tap changer (OLTC) at the
secondary side of the substation transformer is proposed and modelled in OpenDSS power flow
simulation to mitigate decentralized supply voltage variations. The stochastic analysis results
are generated from a pool of real-life 1860 consumer and 1136 PV profiles. The proposed
mitigation may possibly allow higher PV penetration without any voltage issues while also
ensuring that with 100% penetration is possible also through the utilisation factor of the feeder.