Wireless sensor networks (WSNs) have not only become an attractive solution for low power implementations and embedded systems but also for the Power transmission and distribution. Research is ongoing to develop an innovative power source to facilitate the running of advanced sensing and communications technology in hazardous areas using WIFI to Power Sensors, Energy Harvesting using novel MEMS Electromagnetic Transducers, Powering sensors with Pipeline heat generated from Flow Pressure, Remotely and wirelessly controlled power source for UnderWater Sensor Networks (UWSN) and UWSN to detect Low Power and Power Spark of electrical equipments
Recently, the Robinson Brothers, a specialty in chemical manufacturing in the West Midlands, U.K., has deployed a wireless transmitter on the steam main supplying its plant.
Another major company, ABB have designed and installed a transmitter that uses energy-harvesting technology to make remote temperature measurements without the need for a power supply connected to the transmitter. This equipment is powered by a micro-thermoelectric generator, which is driven by the temperature difference between the steam pipe and the ambient surroundings, and communicating with the plant’s control system via WirelessHART, the temperature sensor/transmitter operates without the need for power or communication cabling.
Researchers have received EPSRC funding to develop a wireless sensor network (WSN) designed to spot faults in electricity sub-stations that can lead to power cuts.
The team led by Prof Ian Glover, a Professor of Radio Science and Wireless Systems Engineering at Huddersfield University will be joined on the project by researchers from Strathclyde University and Dr Maria de Fatima Queiroz Vieira, from the Federal University of Campina Grande in Brazil, will develop a WSN capable of sensing partial discharge (PD) in electricity sub-stations, a situation that occurs when the insulation of cables and other power equipment becomes old or damaged.
According to the Professor Glover, if the electricity sub-stations is left unchecked, partial discharge can lead to dangerous and destructive faults including explosions and power cuts. The system will be designed to be monitored centrally permitting the new WSN to allow operators to replace planned maintenance with condition-based maintenance.
This is a major improvement to the traditional approach to PD detection using free-standing radio receivers, which was used to measure the difference in time-of-flight from the PD source to a set of spatially separated receivers.
‘The difference in the times-of-flight are found by cross-correlating the noise-like time waveforms arriving at the different receivers with each other,’ Glover said. ‘The difference in the times-of-flight for a pair of receivers defines a locus of points on which the source of PD could lie. Multiple loci, resulting from multiple pairs of receivers, intersect which gives the location of the source.’
The project which expected to last 4.5 year has received £670,000 from the funding body, and aims to develop a system that relies principally on measurement of PD signal amplitude and does not rely on time measurements.
One challenge, said Prof Glover, will be to make the sensors sensitive enough to detect PD at a useful range without requiring sophisticated signal processing, such as the cross-correlation used in the time-of-flight approach.
He said, ‘Such signal processing is power hungry and these sensors will probably need to be powered using energy harvesting technologies – solar cells, vibration, stray electric and magnetic fields, for example – if they are not to require expensive maintenance.’
Another challenge, he said, is that the loss of the PD signal in propagating from source to receiver may vary significantly, even for paths of the same length due to the complex propagation environment of the substation.
‘This means that the location of the PD source is almost certainly not possible by simply inverting a path loss law since the path loss law will be unknown,’ said Prof Glover. ‘It may be that we have to ‘calibrate’ our sensors using an emulated PD signal. This itself will require power and may further challenge the energy harvesting solution to maintenance avoidance.’
It is hoped that the new WSN system, field testing of which is expected to start in around 24 months, will give electricity operators the confidence to continue running ageing infrastructure efficiently and economically. It could potentially have export potential too.
‘Electricity sub-stations are pretty much the same the world over, the technology’s the same, the problems are the same,’ said Prof Glover. ‘There are many countries in the same situation as the UK with ageing assets and limited funds to replace those assets.’