Radio teleswitch


Radio teleswitch

The Radio Teleswitch Service (RTS) has its origins in the energy management projects initiated in the United Kingdom by the Electricity Council in the early 1980s. Three projects investigated the feasibility of using the telephone network, the distribution network and national radio for large scale energy management purposes. The radio teleswitch project was chaired by Walter Waring deputy chairman of Eastern Electricity and supported by the BBC. The idea of phase modulating control and data signals onto the low frequency carrier wave used for broadcasting the BBC Radio 4 programmes was tested. The BBC was satisfied that there was no discernible distortion of its broadcast service and no infringement of its Royal Charter. The technique won the Queen's award for technology while its application for controlling consumer tariffs and loads was approved by the Home Office. The project was funded by the CEGB and the mainland electricity boards who were each allocated one of 16 message channels. One channel was reserved for testing and the final one was allocated to Northern Ireland when it joined the project.

Operation

Each of the user companies (The "RTS Users", or "Service Providers") have their own database on the Central Teleswitch Control Unit (CTCU), which is a VAX computer running VMS for reliability and minimum downtime. The database defines how each group of teleswitches belonging to the user-company will control the loads and meter registers connected to it. The CTCU uses the database and certain rules to generate and control a continuous string of messages which it forwards to the BBC for transmission. Although each message will be received by all installed teleswitches, the unique user and group-codes carried by the message ensure that only teleswitches carrying the same combination of codes will act on it.

Service Role

For convenient and practical operation of the system the Users needed to set up or appoint an organisation to take overall responsibility for managing the delivery of the service. The organisation needs to hold nominal ownership of the system and IPR and as an agent to enter into and manage contracts necessary for the delivery of the service. The managing agent also provides co-ordination and liaison roles between all the parties concerned.

Formal Agreements

The Electricity Association (EA), which was previously known as the Electricity Council, entered into a renewed formal agreement with the BBC in 1996 as an agent of the users. The EA had also negotiated an agreement with the National Grid Company (NGC) concerning the servicing of the CTCU. Since 2004 the functions of EA regarding this contract have been taken over by the Energy Networks Association.

further discussions

The radio teleswitch concept arose to solve the problems caused by off peak electricity storage heaters, which, in turn, was driven by the perceived cheapness of overnight electricity from nuclear. It probably also arose because it has become possible to modulate a signal onto the Radio 4 long wave.

There were (and are) two main problems with off peak storage and the white meter (ie low cost nighttime electricity).

The heaters provide most heat when it is least needed (ie first thing in the morning), and least when users wanted it (ie 6.00pm in the afternoon). So they have to provide an afternoon boost (and a relatively low peak time), but still at an expensive time.

There is a short term surge when the heaters come on, as they tended to have their clocks set to come on at the same time. In part this was solved by having inaccurate clocks, and also by having a randomness about when the cheap rates come on. Rarely are the meters actually set to operate at the precise advertised times. Dealing with this surge risked becoming an bigger problem than the one it was aimed to solve.

The use of low cost electricity at night is quite widely available, but is subject to variation as to the changeover time. If you set your dishwasher to at the time when cheaper electricity notionally begins, you may well be lucky, and achieve this, but you may not be, and pay full rate for what you think of as cheap rate. What is happening now is that there is often a delay 3 hours button on the devices, so that, if you set it late at night, you can be fairly certain it moves to the cheap period. But using advertised time to switch you devices is not particularly reliable. (and I suspect it always says this on the packet.)

There were various attempts to solve this. Stephen Salter suggested (in 1978) that a timed teleswitch should be operated according to a voltage trend, as such loads have an effect on local voltage. So they would tend not to switch all at once. He also suggested frequency as an influence.

None of these are particularly satisfactory, and, I understand, many radio teleswitch systems have fallen into disuse. In part this is because they are under the control of the DNOs, but many electricity retailers (suppliers) are served by the same channel, and not all wish to have the same tariff time boundaries. So who should control the teleswitch?

Although electric heating may well be best avoided, (if there are alternatives) it is unlikely that wind will come at off peak times. What you need is these devices to come on when it is most appropriate.

I am suggesting that the radio teleswitch should not attempt to control the devices, but instead broadcast a future price curve signal (probably one per electricity retailer), so that devices can see the expected future price over the hours (and days) ahead. This means the heaters etc, can plan their consumption to both meet the consumers needs (hot water or clean dishes by a specific deadline) and do so at the minimum possible price (perhaps even choosing their retailer for the night!.) If the wind forecast changes then the forecast price curve will change, and devices will replan (or, if the price has gone too high, fall back to a cheaper deadline). When people set up the device, they can be shown the different costs of different deadlines.

One time when a price replan would be most helpful would have been in late May, when Sizewell triggered off, leaving the electricity system short of electricity for 2 days or so. This would have been a good time to discourage devices from consuming, by raising the price, or narrowing the off-peak time.

While the behaviour of individual devices will not necessarily be predictable (it depends upon all sorts of things, not least the urgency of need of the consumer) a population of devices will behave pretty predictably (just as a supermarket can predict and influence the consumption of baked beans from the price they choose). Indeed, a population of devices will behave in an entirely rational way, unlike us, whose rationality tends to be bounded.

As more and more devices get put in place, an electricity retailer would have the ability to influence demand and its timing over the period ahead. This gives them much more opportunity to play in the electricity markets, where otherwise they have very limited market power (unlike generators). So it allows them to avoid some of the wholesale price spikes (and other aberrations of the system balancing cash) that are a significant risk to them at present. This significantly reduces their costs, and so makes the whole electricity system a lot more efficient. The demand can be tuned to available generation, rather than, as now, generation has to be available to meet demand.

There are complications about metering, and settlement, but these are both in need of a serious overhaul in order to provide sensible incentives to low carbon behaviour, it is time this was seriously debated.

The radio teleswitch idea needs updating to today’s needs of ambient renewable penetration, and a more sensible economics in electricity.

References and more information

# Adapted from: "An introduction to the Radio Teleswitch Service". Shau Sumar - EA internal document, 2003.
# British Standards: BS 7647:1993 "Radio teleswitches for tariff and load control"
# [http://www.energynetworks.org/ Energy Networks Association]


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