Smartening up power infrastructure

28 August 2011 (Last Updated August 28th, 2011 18:30)

Many power grids operate under the burden of aging infrastructure, but can smart grid technology paper over the cracks? Mitch Beedie asks whether smart metering and smart grid technology could be enough to ease the pressure off aging infrastructure without the need to raise consumer prices.

Smartening up power infrastructure

Power infrastructure is the most ignored, least 'sexy' part of the power industry, and as a result many countries have aging transmission and distribution (T&D) systems.

Old and creaking centralised grids are making it harder to meet peak demands, made worse by a general difficulty in adding new generating sites and transmission lines.

Modernising T&D will however drive up electricity prices at a time of rising fuel costs and the need to replace coal fired power stations with renewable energy sources.

Many utilities are therefore adopting a 'make do and mend' maintenance philosophy. However, security of supply is becoming more important to customers with computers and other sensitive equipment.

They will become particularly angry if, on top of doubling their electricity bills, their utility starts blacking out their supplies.

Smart meters are being marketed as a solution to all these problems, but adding a smart meter to every house would bring another huge expense. Another lower-cost approach improves visibility of the infrastructure and focuses maintenance efforts to where they are needed.

The promise of smart meters

"Power infrastructure is the most ignored, least 'sexy' part of the power industry."

Proponents are certainly making a smart meter in each home sound attractive for utilities. It will do away with meter readers, improve billing accuracy, and help prevent electricity theft.

Multitiered tariffs will mean customers will reduce demand peaks, as could automatically switching off appliances during peak times. It will help operators to move from centralised to distributed grids, tying in (distributed) renewable supplies along with energy storage and charging stations for plug-in electric cars.

Grids will be able to avoid power quality drops and outages, and respond faster to supply disruptions. Keeping within capacity ratings of electrical lines and transformers will extend T&D system life, while reducing peak demands could save utilities huge amounts of money by delaying or eliminating upgrades to the grid.

With all that, who could object? Customers paying the bills, for a start. Utilities often take advantage of the extra information to push up bills with complex multitiered electricity rates that confuse and annoy customers and so lose the public relations argument before it starts. And upgrading all those meters and analysing the massive volumes of resultant information will be hugely expensive.

The real world

Some of the claims made for a meter in every home are doubtful. Electricity meters are often read at the same time as gas meters, and there will be little advantage to customers if meter readers still need to read those.

Improving the accuracy of bills and preventing electricity theft will be nice for the utilities, but are hardly their most pressing problems. Plug-in electric cars are not yet common, and will not reduce CO2 and pollutant emissions as long as the electricity is supplied by burning coal.

Multitiered tariffs and higher prices will hit the poor, pensioners and unemployed worst – particularly those who are at home during the day. And many households will not be able to transfer heating / cooling and cooking to off-peak times.

The extra information can be gained without fitting smart meters in all homes. Fitting them in substations also makes the grid smart. It can bring most of the benefits of a meter in every home, and is much, much, cheaper. 

Smart grids at the transmission level

In substations, smart meters and smart grid technology can help implement condition based maintenance programmes. A demand / supply model can be continuously updated, estimating power flows and calculating voltage stability margins. That gives valuable data on the health of transformers, circuit breakers and other equipment. That in turn keeps reliability high while reducing maintenance costs, particularly for an aging infrastructure.

"Many utilities are therefore adopting a 'make do and mend' philosophy."

Intelligent electronic devices, remote terminal units and disturbance and assets monitoring systems can feed information on critical equipment back from the substations into supervisory control and data acquisition (SCADA) systems.

These run the energy management systems, with network state estimators, network application models and analysis tools helping to ensure reliable operation.

Systems continuously compare voltages, currents and temperatures to operating limits to look for potential overloads. They calculate the magnitude and direction of power flow, reactive dynamic reserves and interconnection status with neighbouring transmission operators. They monitor and control the remote equipment to prevent failures, minimising the effects of any failures that do occur and restoring service afterwards. Analysing post event information helps assess the condition of aging infrastructure to determine where system improvements are needed.

Independent transmission developer ITC in the US uses this approach. According to Terry Harvill, vice president of Grid Development at ITC, the company implemented a programme specifically to improve event analysis for shortening response times and identifying corrective actions. It uses PowerWorld software to generate a dynamic wide-area graphical view of the entire system.

Analysing the readings helps assess transmission system reliability, spotting (for example) temperature trends that can predict equipment failures. That gives early indication of specific failures rather than only general status alarms.  It also reduces the need for field calibration and inspection. ITC monitors the various elements of their major transformers, measuring dissolved gas in oil, bushings, temperature, and current monitoring of fans and pumps. The industry standard ICCP (inter-control center communications protocol) exchanges data with other control rooms, local distribution companies, and system and generation operators.

Even here, though, smart meters have limitations. Smart grids can help manage grid loading to reduce the stress on old or deteriorated system components, but that doesn't improve the condition of the components themselves. William Snyder, vice president at Quanta Technology, remarks that sensors do not locate broken conductor strands or insulators outside the substation, or detect corrosion of lattice tower legs or foundations. The visible sections of transmission towers have likely been well painted and maintained, but buried sections are less likely to have been maintained. The condition of underground and ACSR (aluminium conductor steel reinforced) cables is often similarly unknown.

Focusing efforts – and money 

"Grids will be able to avoid power quality drops and outages, and respond faster to supply disruptions."

People arguing against adding high-tech solutions to our energy crisis, like an energy meter in every home, are sometimes accused of being Luddites. The accusation from the other side is that advocates are just being hypnotised by shiny new things, which actually only still further delay the adoption of real energy saving measures. Utilities should therefore study results of smart project pilots carefully, watching out for voluntary projects that will distort results by self selecting people interested in conserving energy. Utilities' highest priority should be on keeping bills down by helping customers reduce their energy consumption, and a smart meter in every home will only divert funds from this.

Smart meters in themselves don't save energy, although they can encourage environmentally and cost-conscious customers to do so. Everyone else will resist paying extra for meters where the benefits are not obvious.

Meters don't need to be installed in every home, only progressively in homes that are renewing electric wiring and fitting renewable supplies. Shifting loads away from peak times does not save energy; it just shifts loads. Energy efficiency is a fundamentally better way of avoiding the need for extra peak supplies.

Rather than sending workers round to install new meters, utilities would be better off spending their time and money in making all the low-cost improvements (including things like insulation and draught proofing, low-energy equipment and LED lights) wherever possible.