Smart sensing
Mark England, CEO of Sentec, considers the possibility of a ‘smart grid’ and the implications that it will have.
A report by ZPryme Research that was conducted in 2009 predicted that the global smart grid market would reach $171 billion by 2014. Perhaps surprisingly, smart metering was forecast as the smallest segment, with only 11% of the total. Communications was next at 16%.
In fact, the largest category was smart sensors and devices, with a full 50% of the market, predicted to hit $85.5 billion. But when you consider the new challenges the grid will face in the coming years, this high market share is easily explained.
As we move towards a smart grid, equipment such as substations will face stresses from new applications on top of the growing challenges in monitoring performance. With many major car manufacturers now showcasing eco-friendly vehicles, it seems that the electric car is on the verge of achieving a long-awaited breakthrough in the UK market. But the grid in its current form would be unable to cope with the pressure from thousands of new electric vehicles, the electrification of residential heating and the input of micro-generated power back into a grid which was designed to transport centrally generated power in one direction; to the end user. Most of the UK high and medium voltage sections of the existing grid are well understood and monitored efficiently, whereas in the low voltage distribution network there is almost no monitoring or control and this area needs to be addressed.
Some distribution network operators (DNOs) in the UK use expensive mobile units to measure low voltage networks, but this equipment has to be moved between transformer units. Currently less than 1% of units are monitored continuously and on each feeder. With Smart Grid Analysis predicting that by 2015 more than $7.5 billion in smart sensors will be sold for applications in electricity grids around of the world, there is a clear opportunity for these products to be developed.
Bringing intelligence to the low voltage grid with a sensing solution is vital to achieving the objectives of an overall ‘smart’ grid. It’s crucial to know the health of major assets in near real time and identify in detail the load those assets are serving so that problems can be pinpointed before they cause trouble. This simultaneously minimises maintenance costs and maximises uptime. ‘Smart’ distribution grids can also help companies scientifically value and prioritise projects and capital investments and co-ordinate and integrate capacity from distributed generation and storage solutions. The low voltage section of the distribution network requires a solution that can be retrofitted to existing infrastructure if it is to be cost-effective and implemented quickly enough. The typical UK substation also faces several specific issues that make a custom designed product an obvious choice.
Space in substations is tight, so product size must be considered. In addition, it’s crucial that there is no disruption to supply when the sensors are being fitted. Ease of fitting should also be a priority in a low voltage sensor, and avoiding the need for calibration on site can make it much quicker and easier to train the fitters to install a new product.
Robustness and reliability once fitted is also vital. Due to the specific substation requirements, the sensor system must be impervious to weather, damp or physical location. To ensure longevity, it’s also important that the sensor can continue to operate under challenging conditions; for example following large fault currents or when installed in external locations over extended periods of time.
When it comes to electricity distribution, accuracy saves time and money. Maintaining accuracy over the full lifetime of the sensor without any need for in situ recalibration is a key improvement over existing technology.
Finally, the cost point of the system must be low enough to enable continuous monitoring on all phases in all substations. The full cost of ownership must also be taken into account including the cost of the sensor system itself, transmitting and processing data, training staff, installation time and maintenance visit time. The business case can also include the savings as a result of the reduction in asset damage from overloads, and the costs of managing unexpected outages.
If predictions hold true, the sensor market is set to boom, but DNOs need to consider the custom product requirements of a low voltage substation. Bringing intelligence to the low voltage grid is vital, and by ensuring that sensors are customised to prioritise ease of installation, durability and accuracy, it will be possible to truly deliver on the promise of a ‘smart’ grid.
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