Power stations once generated electricity at a rate of hundreds of kilovolts which then cascaded down through the power network to come out of a domestic powerpoint at 230 volts. But there are now many more ways of generating electricity and the power grid now has to take account of generation sources such as wind turbines and even domestic solar generation capability.
Those new sources – especially in renewable energy – can generate unpredictable supply, and the power grid has to be more carefully managed to ensure it does not become overloaded and that there is never a shortage of electricity available.
In the old-fashioned, power station-based generation industry, management was simple. Large power stations such as Drax or Sizewell would generate electricity and any issues could be handled by calling the control room at Drax.
Now though, with tens of thousands of wind turbines,the picture is radically more complex and the only way to safely manage a national power network is through increased communications.
‘In terms of energy, the gas industry is stable and hasn’t really been affected in recent years, all the action is in electricity,’ says Adrian Grilli, managing director of the Joint Radio Company, a joint venture company of National Grid plc – the UK electricity transmission and gas transmission and distribution operator – and the Energy Networks Association Ltd. JRC, formed in 1955, represents UK gas and electricity transmission and distribution companies and has responsibility for managing the fuel and power radio spectrum.
Grilli sees the change both in the nature of electricity generation and in the emergence of smart meter networks. He points out that the UK is unique because the smart meter network is the responsibility of the electricity suppliers, while the energy distributors are responsible for a separate distribution network. Most European countries use one network for both.
On the distribution side, increased complexity is necessitating greater communications capacity. ‘Now you might have 10 or 15 thousand wind turbines generating – or not generating – electricity, so it’s a much bigger communications and control issue than dealing with just one large power station,’ he adds. ‘You need to know when they’re generating and when they’re not.
‘You have a vastly increased number of sources of energy on the network, which are completely independent and random,’ says Grilli. ‘The [distribution companies] are in the process of upgrading their networks [which is acceptable] while renewables are only a small percentage of network but, when the percentage rises to a significant proportion, you have to be able to control it.
‘1% of wind power doesn’t make much difference but, once you get to 10% and the wind blows unexpectedly, you have 10% more generation suddenly appearing and you have surplus generation,’ Grilli adds.
The converse is also true. If the wind doesn’t blow as forecast you lose 10%, and with a traditional power station taking five hours to get up to speed, it’s clear that deviations from forecasts of even one hour can have a substantial effect.
‘As [renewable generation] becomes more significant you need to track wind across the UK by monitoring and you have to be able to switch off [turbines] remotely from the network operations centre,’ says Grilli. ‘A lot more control is necessary and a lot of these sites are highly dispersed.’
Another foible of the UK market is that a lot of the energy is generated in the north of the country and consumed in the south, so distributors have to have the transmission capability to get it to consumers.
The only way to manage this safely, says Grilli, is to deploy ‘a lot more communications’. To do so, distributors have deployed private radio – mainly in the form of UHF radio – and that looks set to continue. ‘When you’re pricing the system, GPRS is useful because it’s cheap to deploy,’ he adds. ‘The issue arises when you start to depend on these solutions and reliability comes into play.’
Transmission capability, for example, is highly dependent on temperature. It’s possible to double capacity from Scotland to 4,000 amps depending on temperature and GPRS can certainly handle that data. ‘It can’t assure that power, though,’ explains Grilli.
‘If monitoring fails, that’s when it moves from discretionary and nice to have to mission critical. Utilities are certainly seeing communications become more mission critical and UHF radio is being used because we haven’t got much else.’
However, as communication increases, alternatives will be needed. ‘In the future, broader band communications are likely to rely on LTE, WiMAX or CDMA,’ says Grilli. ‘Mobile operators will take strides to increase the resiliency and reliability of their networks, but there will continue to be a dividing line between private and public networks.’
Grilli points out that in the event of a massive power outage, the commercial cellular networks will cease to operate. Partly for that reason, not all communications will be wireless. ‘The networks are rolling out a lot more fibre,’ points out Grilli.
‘We’ve also got powerline communications so the mains can be used for signalling. Distributors like Western Power have a lot more resiliency because their territory is much more stormy than London, where links are all underground and it’s difficult to use UHF because of the building density. In addition, there’s very little generation in London.’
Even so, the trend is towards much greater instability in power networks. ‘Around the world, networks will become much more unstable because of the changing nature of supply and demand,’ says Grilli.
‘Government strategies for carbon reduction including electrical heat pumps place an increasing load on the network. On a cold winter’s day, three quarters of energy comes from gas and gas is inherently stable and storable – electricity is not.
‘If you push space heating onto electricity, you increase demand but you haven’t got the option of more storage, the only way you can manage it then is through more effective communications.’
The flip side of energy-related communications is that the UK has decided to initiate a separate smart meter network.
‘The UK is unique with smart meters in that they are the responsibility of every supplier rather than the distribution company,’ he says.
That will mean two power-related networks are built. ‘One could say, wouldn’t that be a bit wasteful,’ adds Grilli.