Medium Voltage Direct Current (MVDC) Systems in Electricity Distribution Networks

BACKGROUND

Conventionally, electrical energy is distributed as Alternating Current (AC), mainly because the voltage can be easily varied using AC transformers, although Direct Current (DC) has many other advantages.

This was the basis of the “Battle of the Systems” between AC (Westinghouse) and DC (Edison) in the early 20th century. The development of power electronics has profoundly changed the balance between DC and AC. Now, DC voltages can be easily varied using power electronics converters.

For Medium Voltage (MV) distribution networks, DC technologies have recently been identified as one of keys to address challenges caused by highly distributed renewable generation and electric vehicles. For example, Sottish Power Energy Networks (SPEN) was awarded the Angle-DC project (£13m, 2015-2020) by Ofgem (the government regulator for UK electricity markets) to demonstrate an MVDC system connecting Anglesey to North Wales, which is the first of its kind in Europe and is expected to be widely replicated.

As the only academic partner of the Angle-DC project, Cardiff University is working with SPEN, EA Technology and GE to address technical challenges raised by this project. As an emerging area, most of existing MVDC technologies are still far from mature. Hence, there is a lot of room to improve existing approaches and to develop new technologies. For example, no preferred topology of power converters, which is at the heart of MVDC distribution networks, has been identified.

PROJECT AIMS AND METHODS

This timely PhD project will focus on the heart of MVDC, i.e., topologies and the associated controllers of power converters. Such converters that are available, are based on electric motor drives. Innovatively, this project will consider their new operation in distribution networks, and so improve system performance.

The project will include:

- Reviewing existing MVDC technologies. (0.5 years)
- Technical specifications of MVDC converters (0.5 years)
- Holistic design of topologies and controllers of MVDC converters (1.5 years)
- Experimental verification (1 year)

At the end of this project, a family of topologies and controllers for MVDC distribution networks will have been developed, experimentally verified and patented.

ELIGIBILITY

You should have obtained, or be about to obtain, a First or Upper Second Class UK Honours degree, or the equivalent qualifications gained outside the UK.

Applicants with a Lower Second Class degree will be considered if they also have a master’s degree. Applicants with a minimum Upper Second Class degree and significant relevant non-academic experience are encouraged to apply