As part of the smart grid implementation, distribution system operators (DSOs) are introducing distribution network automation. Although there have been academic studies on designing automation schemes from a theoretical optimisation viewpoint, it is essential to approach this from a DSO operations engineering perspective.
The research objective of our study was to obtain an optimisation method to determine the most appropriate substation locations, for an existing 11kV network, where the DSO will install automation technology.
The research presented an innovative approach of how to select substation locations to optimise the network operations of a distribution network by considering different operational aspects engineers experience during switching operations to restore the supply.
It was necessary to have a method to reduce the restoration time as much as possible. This led us to investigate an optimisation method to select the substations which reflects the real constraints of a network.
The optimisation method, using a genetic algorithm, considered customer minutes lost, energy not supplied, type of customer connected to the substation (e.g. hospital, commercial, renewable energy sources, military, etc); substation access and location; MV switchgear operation; budget availability; equipment cost for different switchgear manufacturers; and the lifetime of automation equipment.
Automating 35 per cent of the network will provide the optimum benefits for the capital cost invested
The main contributions from this research comprises the identification of actual restoration time, an optimisation method that includes the substations site restrictions experienced daily, comparing optimised results based on transformer rating or transformer peak power and a method, that for a given budget, gives the optimum substations locations, which will provide the least time to restore supply.
The research analysed typical networks in the UK and a Maltese 11kV network. It concluded that automating 35 per cent of the network will provide the optimum benefits for the capital cost invested.
The case study results for Malta gave improvement of 26 per cent and a cost savings of 16 per cent.
The DSO will use funds not spent to improve the same network by replacing switchgear, upgrading old cables having lower capacity and installing new cables.
John Caruana is a divisional manager distribution with Enemalta. He is a visiting senior lecturer at the Department of Electrical Engineering, University of Malta, and visiting industrial lecturer in power distribution engineering at Newcastle University.
Caruana holds a B.Eng from the University of Malta, an MSc in power distribution engineering from the University of Manchester and successfully completed a PhD in electrical engineering from Newcastle University. His research was partially funded by the Malta Government Sponsorship Scheme.
Sound Bites
• For over a century, researchers have thought that the patterns of brain activity that define our experiences, hopes and dreams are determined by how different brain regions communicate with each other through a complex web of trillions of cellular connections. Now, a study has examined more than 10,000 different maps of human brain activity and found that the overall shape of a person’s brain exerts a far greater influence on how we think, feel and behave than its intricate neuronal connectivity.
• For the first time, scientists have recorded brain activity in a free-ranging, wild marine mammal, revealing the sleep habits of elephant seals during the months they spend at sea. The new findings show that while elephant seals may spend 10 hours a day sleeping on the beach during the breeding season, they average just two hours of sleep per day when they are at sea on months-long foraging trips. They sleep for about 10 minutes at a time during deep, 30-minute dives, often spiralling downward while fast asleep, and sometimes lying motionless on the seafloor.
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DID YOU KNOW?
• The farthest object visible with the naked eye is the Andromeda galaxy, 2.7 million light years away
• Half the world’s cheese is made using enzymes from one Danish company.
• The marine biologist Joel Hedgpeth was the founder and sole member of the Society for the Prevention of Progress. He rejected all membership applications, because ‘growth in members would represent progress’.
• The King’s Royal Hussars regiment owns the looted silver chamber pot of Joseph Bonaparte, Napoleon’s brother, and their officers regularly drink champagne from it.
For more trivia, see: www.um.edu.mt/think.