Developing DC Circuit Breaker Tech for Renewable Energy Integration

£75,000 has been awarded by the Scottish Enterprise High Growth Spin-out Programme (HGSP) to a renewables project spearheaded by the University of Aberdeen (UA). The project focuses on developing the LC Direct Current Circuit Breaker (LC DC CB), a key technology hoped to advance renewable energy integration in Scotland.

 

A new CB technology could be the key to renewable energy integration in Scotland. Image used courtesy of Pixabay

 

AC and DC Transmission

If you were looking at a graph depicting voltage vs. time for direct current (DC), electricity travels in a straight line, indicating it has no frequency, and its voltage stays constant. On the other hand, as the term implies, alternating current (AC) alternates polarity 50 to 60 times per second (depending on location). This gives it a frequency and suggests its voltage does not remain constant over time (it decreases and increases).

DC and AC are two different ways of transmitting and distributing electricity. DC is the oldest form of electricity transmission, while AC has become the most popular form in modern times.

Some of the merits of DC transmission include the ability to store electricity in batteries, lack of delay or advance in the circuit, and the efficient use of power due to the lack of reactive power. In AC, reactive power is generated as power travels to and throw between the power source and load. An electrical load can be defined as any circuit element that consumes energy.

Another benefit of DC transmission is that it does not require power inverters, which can be inefficient. Removing the need for inverters also lowers the cost of DC systems. DC systems are suitable for high-power and long-distance transmission. Unlike DC transmission lines, AC lines can disrupt communication on other lines.

 

A New Generation of Circuit Breaker Technology

A DC CB is a device used to protect electrical circuits from overcurrents. It detects when an electrical circuit's current exceeds a certain threshold and then automatically disconnects the circuit. This helps to prevent circuit damage from overloads, short circuits, and other faults. DC CBs are commonly used in automotive, marine, and industrial applications.

Current DC CB technology is considered costly and slow in operation speed compared with AC CB technology, which has held back the wider adoption of DC transmission and distribution systems.

 

From left to right: Technician Richard Osborne and Professor Dragan Jovcic standing next to the DC CB. Image used courtesy of UA

 

Professor Dragan Jovcic from UA’s School of Engineering has been developing the LC DC CB since 2018 to improve DC CB technology, including operation speed, by achieving faster commutation, which can be done by changing and integrating certain CB components. Such components might include a parallel capacitor and type of switch.

Current commutation is switching current from one source to another in a DC circuit breaker. It controls the current flow from one device to another to prevent damage or disruption. Current commutation is important for any electrical system as it allows for safe and efficient operation. It can be used in various applications, such as power supplies, motor controllers, and even DC motors. In addition, current commutation can protect against overloading and short-circuit conditions. Using a combination of electronic switches and relays, current commutation can ensure that only the necessary amount of current can flow through an electrical system.

Jovcic endeavors to further develop the LC DC CB technology for commercialization and establish a spin-out company with which to do so. Jovcic is working alongside Royal Society Entrepreneur in Residence, Paddy Collins, to achieve this. Under the EU Horizon 2020 project PROMOTioN, experiments and testing on LC DC CB hardware prototypes have yielded positive results.

The LC DC CB is hoped to push forward electrification efforts and green hydrogen generation at a large scale.