Novel ‘tap-changer’ development and concept demonstration
The novel tap-changer addresses the challenge of voltage control in low voltage (LV) local distribution networks with increasingly uncertain and rapidly varying loads. It can provide high fidelity voltage control where currently this is a fix ratio with any balancing being performed at a much lower resolution at higher voltages further up the network chain.
Electricity distribution network operators have a duty to ensure that voltages delivered to customers are close to nominal values, for example 230 V @ +10% & −6%. They have to do this for all customers, and on all timescales, from seconds to years. The difficulty is that there are small voltage drops throughout the network itself: the cables and overhead lines each have some impedance (combination of resistance and reactance), which causes a small drop in the voltage whenever a current flows. Balancing of voltages is performed at much higher voltages in the electrical system, meaning there can be great variability at the low voltage side when uncertain and unsteady loads are drawn, i.e. local feed-in energy distribution from photo-voltaic cells and charging of electric vehicles.
The aim of the project was to develop a compact and low cost tap-changer based on the sponsors established patent to address the issue of voltage control in LV networks. It can provide control of the secondary distribution transformers that feed 'local' networks and so provide much greater control of voltages delivered to customers in the presence of much greater local load uncertainty. Many distribution network operators are currently considering the possibility of introducing voltage control mechanisms to their LV networks due to these uncertain loads that are becoming larger and much more unpredictable.
This project has developed from a theoretical concept through various stages of modelling and design to create two generations of prototype demonstrators. The ‘tap-changer’ is available to view in the Control Group laboratory. Contact Sharon Henson to make an appointment for a demonstration.
Dr Chris Ward - Senior Lecturer in Control Systems Engineering
“This project has enabled a private investor to tap into the research expertise available in the Control Systems Group and develop an idea from concept through to demonstrator. The next step is to test the tap-changer in a real-world environment.”