Using OLTC-Fitted Distribution Transformer to Increase Residential PV Hosting Capacity: Decentralized Voltage Management Approach

Abstract

The increasing Photovoltaic (PV) penetration in residential Low Voltage (LV) networks is likely to result in a voltage rise problem. One of the potential solutions to deal with this problem is to adopt a distribution transformer fitted with an On-Load Tap Changer (OLTC). The control of the OLTC in response to local measurements reduces the need for expensive communication channels and remote measuring devices. However, this requires developing an advanced decision-making algorithm to estimate the existence of voltage issues and define the best set point of the OLTC. This paper presents a decentralized data-driven control approach to operate the OLTC using local measurements at a distribution transformer (i.e., active power and voltage at the secondary side of the transformer). To do so, Monte Carlo simulations are utilized offline to produce a comprehensive dataset of power flows throughout the distribution transformer and customers’ voltages for different PV penetrations. By the application of the curve-fitting technique to the resulting dataset, models to estimate the maximum and the minimum customers’ voltages are defined and embedded into the control logic to manage the OLTC in real time. The application of the approach to a real UK LV feeder shows its effectiveness in improving PV hosting capacity without the need for remote monitoring elements.

Modular PV System for Applications in Prosumer Installations with Uncontrolled, Unbalanced and Non-Linear Loads

“…Obviously, this method cannot be the online solution for the occurring PQ problems. Reinforcement of the network comprising the replacement of distribution transformers with ones having on-load tap changers (OLTC) could help (an example is presented in [14]), but it is difficult due to the high cost of OLTCs and the outage needed for the transformer upgrades [14,15].…”

Harmonic Loss Analysis of Low-Voltage Distribution Network Integrated with Distributed Photovoltaic

“…Because of clean and sufficient solar energy resources and convenient installation methods, such as "roof photovoltaic", the economic and environmental benefits of the PV generation system are continuously improved [3,4]. When a high proportion of distributed energy is connected to the power grid, the change in configuration and operation condition of the distribution network is huge [5] and the power flow of the distribution network has significantly been changed [6,7]. On the one hand, distributed PV will affect the power flow of the distribution network, directly affecting the loss of lines and equipment [8].…”