Using the grid as a communication network has long been a goal of internet developers — there is a wired connection into every home in the country — but now it looks possible to use this connection to manage the demand-side response market.
Time to communicate better with the demand-side response
Demand-side response, where the output of large electricity loads is adjusted to balance the grid, could soon benefit from a technology that sends and receives instructions to participants over the transmission and distribution system.
Demand-side response along with energy storage is an important tool in the box for creating more robust and resilient grids. Each approach imparts some much-needed flexibility to grids. Energy storage does so by responding rapidly to grid signals, in a second or under, to inject or absorb power to compensate for real-time mismatch in consumption and demand.
In demand-side response programmes, participants — typically government departments, businesses and industrial energy consumers — adjust their energy consumption patterns to take the edge off peaks in demand by turning down or switching off loads during times of high demand.
Both DSR and energy storage can earn revenues from ancillary grid service markets.
Communicating with assets in a demand-side management programme requires a reliable internet or mobile communication connection in addition to an individual meter, which can make the technology too expensive and impractical to extend the benefits of DSR to thousands of smaller assets, like water or electric heaters in homes, for example. Many assets are excluded from existing DSR arrangements due to a lack of remote connectivity.
The investment required to install equipment even for businesses thinking about performing DSR services can be costly. This is putting off would-be participants in the commercial and industrial sector, which transmission system operators such as the UK’s National Grid are trying to attract to provide demand management.
Reactive Technologies has developed what it calls a grid data and measurement system (GDMS), which provides a cost-effective alternative by using the frequency of the electricity network to carry data.
“Unlike cellular networks where there are often patchy reception areas, sending data via the grid’s frequency provides full coverage of the UK,” says Marc Borrett, chief executive of Reactive Technologies.
Measuring output from renewables
GDMS allows connected devices to share information and enables remote control and measurement of generators and consumption devices across electricity networks. Potential applications extend beyond the functions of smart meters.
They include communicating with assets connected to the electricity network to measure and control their energy consumption or generation.
The grid frequency communication technology, which works in real time, can also be used to measure the generation profile of grid-connected solar or wind farms, as well as other types of generators, providing their owners, grid operators and local distribution network operators with greater visibility of how these assets behave on the network.
“Through this visibility the technology allows for better utilization of intermittent resources, rather than curtailment, when they generate energy when there is not necessarily the demand. By putting a receiver on the asset the distribution network operator will know whether a solar farm’s output is 8MW or 10MW,” Borrett says.
Earlier this year Reactive Technologies completed a pilot with the National Grid and the distribution network operator SSE.
“SSE provided us with the infrastructure and sites where we could broadcast from. These were primarily substations with the National Grid providing access to the transmission level infrastructure. There was one power station in the pilot too.”
Typically, energy retailers and large commercial customers have the means to participate in demand response programmes.
Connected devices send and receive data across the electricity network through minute and subtle changes made to the grid frequency by modulating the power consumption of transmitting devices.
These frequency changes create a unique code. Receivers that are embedded in loads are programmed to detect the frequency changes. They identify and decode the messages, which are instructions to tell the load or appliance to carry out an instruction, turning down, or switching off according to a schedule, or based on grid frequency changes.
“We are looking to address a gap in the market where you don’t need to rely on an internet connection. That means we can potentially reach more assets compared with current demand-side response technologies,” says Borrett, whose background is in telecommunications.
The hardware — the receiver — can be embedded in plugs, potentially allowing air-conditioning units, thermal heaters, electrical storage heaters, hot water tanks and freezers, appliances that are found in millions of homes, to benefit from providing demand-side services.
By the end of 2017, Reactive Technologies is aiming to have some small pilots with energy suppliers and the company is also talking to distribution network operators. However it could be a few years before a residential DSR rollout happens using the technology.
The data provided by GDMS can provide a clearer picture of how electricity is generated and consumed at the distribution network level. Such information is essential for operators tasked with balancing electricity networks which are becoming increasingly complex with the greater variety of assets connected to them, such as rooftop solar, energy storage and electric cars.
Commercialized smart grid technologies, which typically use sensors, software and other technologies to monitor assets like medium and low voltage cables and equipment, have to send data over GPRS networks. Therefore a significant part of their platform offering to utility customers includes ICT products such as communication modules and modems.
To ensure the reliability of sending data over general packet radio service (GPRS), suppliers of smart metering and smart grid products and systems have to improve their modems. One such player has had to address the problem of what can happen when a cellular area experiences outages or a smart meter drops out of the network by implementing a logging feature in its modems, to log key data to identify issues causing data transfer failures.
There have been various attempts to send data via local electricity networks, such as a single building, known as Power Line Communications (PLC). However, these technologies are limited in range and cannot send a signal through transformers or over long distances.
The pilot of Reactive Technologies’ grid communication technology with the National Grid and SSE is thought to be a world first in sending data through an entire electricity network over long distances and through transformers even to the very fringes of the grid, such as appliances in homes and businesses.
An important and relevant concern that is accompanying the rise of smart grid technologies is the issue of security and privacy.
GDMS does not know or communicate any private user details, just high-level service descriptors, as in “water heaters in the south-west of England”. However, trusted encryption techniques can be used to ensure data security.
Because it uses grid frequency, the technology can identify whether it is communicating with a real asset as opposed to a virtual one, which could address fraudulent misappropriation of energy concerns as digitalization and smart grid infrastructure is increasingly adopted.