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Engineers tackle energy sector

- By Erna van Wyk

This year’s School of Electrical and Information Engineering Open Day tackled South Africa’s energy problems through fourth year projects that focussed on improving the country’s current reliance on Eskom and its electricity supplying affiliates, as well as improving the battery management for solar power systems.

Held on 15 October 2014, Open Day is an annual feast of projects developed by the School’s final year students. The six-week project development phase mirrors the industry challenges these students will face such as short time frames and resource constraints.

During Open Day students do not only show off their work to parents, fellow students or lecturers, but also to industry representatives and prospective employers.

Two projects specifically targeted the country’s energy dilemmas and the students came up with innovative small changes that could result in huge improvements for electricity suppliers as well as consumers.

 

 Investigation into the use of a medium voltage power cable as a data communications channel by Gregory Arendse and Vernon Avis

Fourth year Electrical Engineering students Arendse and Avis investigated the viability of a power line communication system implemented on medium voltage (MV) power cables found within electrical distribution grids. Arendse explains their system:

“I specialises in Information Engineering and Vernon in Electrical Engineering and with this project we were able to bring our two fields together. Our worked focussed on smart grids that can monitor power usage and Eskom’s assets without having to put in any additional infrastructure.”

“A lot of research has been done on low voltage PLC (Power Line Communication) cables but we looked at medium voltage cables – the lines that join your substations to the distribution points. Although it is further from the house, we wanted to see if it can be used as a backbone network to send data to the electricity supplier. And it worked – we could send data on a medium voltage cable.”

“There could be different applications of this system. For instance, Eskom metres in your house need to be manually monitored by Eskom workers who would come around to read your metre and take the data back to Eskom. In principle we could automate this process, put a metre in your house that could be read remotely from Eskom’s offices rather than through sending someone to your house. It is automated and could be read more often.”

“This can assist in more control in the accuracy of billing systems. But this is not the main purpose of our project. It is rather to have more control of the system to improve maintenance and lessen loadshedding.

“An electricity supplier such as Eskom will be able to see where in a city high amounts of electricity are being used, when a cable is being removed through cable theft or when there are other faults on the system. Because loadshedding occurs when, for instance, transformers get overloaded or damaged and needs to be repaired, this system will alert the electricity supplier who will then be able to put pre-emptive measures in place to avoid power cuts or loadshedding.”

“Our project is aimed at how we get the information from point A to point B through using the existing cables that are already in the ground, and saving the electricity supplier additional infrastructure costs.

“Research into this field is already being done, but we wanted to specifically see the response of 11kW XLPE power cables – used widely in South Africa – when we put data on the cable. The tests were conducted in a very theoretical closed-environment and more real-world testing is needed, and although we could not do all the tests we wanted to do, we found that we could send data across the cable.”

 

 Improved battery management for solar energy systems by Claude Simoes Permuy and David Edwards

Permuy and Edwards are fourth year Electrical Engineering students and took on the challenge of improving the lifespan of batteries in a string. Permuy explains their system:

“The world is relying more and more on renewable energy and batteries are a big part of it. In South Africa we have great solar and wind energy opportunities. This energy is stored on solar batteries connected together, but the differences in the batteries quickly cause unbalances in the system.

“No two batteries, even from the same factory, are identical. They all have slight differences. Inevitably, when the batteries are connected in a series, one of them will start to degrade. This unbalance is the result of under- or overcharging that in turn leads to degradation and a shorter battery life. The degradation is on the whole string and it results in less charge capacity and less energy.”

“We have developed a battery management system that measures the difference in the two batteries and turns on a DC-to-DC-convertor that charges each of the batteries separately. The microprocessor decides which flayback or mini charger it should automatically switch on to charge the batteries that need be charged at a specific time. It is a system that is beneficial to anyone who uses batteries in a string and the benefits include longer lasting batteries that save a lot of money in the end.”

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