Danger, danger, high voltage

Jon Hiscock, chief executive of Fundamentals, highlights the growing importance of voltage control on distribution networks in a world of intermittent renewable generation and fast-changing customer demand. 

One of our clients called us recently to tackle the problem of a customer who could not charge their electric car, because the voltage they supplied was too high, tripping out the charger safety circuits. Just one example of a growing problem in the medium and low voltage distribution sector.

Our motorist’s problem was that they live in a housing development with a lot of rooftop solar panels, causing voltage surges in their local part of the network on sunny days. A typical converse scenario affects end-of-network communities. Their distance from main substations already causes voltages to drop. With increasing demand from all manner of electrical equipment, voltages can fall to the point where they cannot function properly.

Both the above issues can usually be fixed with the addition of voltage control units locally, but these are effectively sticking plasters. The big picture is that transmission and distribution operators are having to address the growing problem of voltage control at a strategic level, across the entire grid.

Strategic voltage challenges

Local problems are symptoms of the root causes of unacceptable voltage variations grid-wide. These are two-fold. Electricity is increasingly generated from a multitude of renewable sources, which are naturally intermittent. A cloud passing over a solar farm will cause a sudden power drop. Gusts blowing across a wind farm cause power surges. Meanwhile, growing numbers of customers need to plug in their EVs and fire up their heat pumps at the same time, causing massive and rapidly-developing peaks in demand.

The challenge of uncontrolled voltages is multi-facetted. It is a cost as well as an environmental issue, because out-of-limits voltages waste energy, increase electricity bills, cause premature equipment failure and produce excess carbon. It is a customer service issue, because consumers rightly demand reliable quality of supply. And it is a regulatory issue, because operators can be sanctioned for supplying electricity outside agreed parameters.

The grid can call on reserve generation capacity and release energy from storage systems to balance supply and demand at the national, high voltage level. But distribution network operators (DNOs) are becoming increasingly involved in controlling voltages at medium voltage and low voltage levels. This has the potential to save customers millions of pounds and cut carbon emissions, whilst minimising the disruption that can be caused to the grid by the connection of ever-growing numbers and sources of intermittent generation.

The technologies exist to drive DNOs’ progress towards better control of voltages at the distribution level. For instance, plug-and-play Automatic Voltage Controller (AVC) relays can be deployed in substations and use a combination of software and digital controls to adjust voltages instantaneously.

Electricity North West Limited’s CLASS

For example, AVCs are at the heart of Electricity North West’s CLASS (Customer Load Active System Services) voltage control initiative, heralded by Ofgem as “a cost-effective, low carbon technology that has the potential to reduce bills to consumers … and can make a major contribution to our full chain flexibility vision for a secure, affordable, net-zero electricity system”.

Ofgem’s approval of CLASS as an example which others can follow is a game-changer. It enables DNOs to become actively involved in managing voltages at distribution level and minimising the need to call on backup generators – short term operating reserves (STORs) – which can be highly carbon-intensive and expensive to run.

CLASS uses voltage control relays in its substations to adjust voltages. These are linked to a control centre, which uses an advanced network management system to balance the distribution network, by responding immediately to changes in supply and demand.

Voltages can be increased or reduced by amounts that are imperceptible to consumers. So, customers’ electrical and electronic equipment will run at the voltage for which it was designed, which saves energy, reduces carbon and extends service life.

Nationwide deployment of CLASS is believed to have the potential to shave £1 billion off UK electricity bills and cut emissions significantly in the coming years. It also has enormous export potential, wherever countries similar challenges in transitioning to low carbon electricity.

Northern Powergrid’s BEET

Similarly, we have worked with Northern Powergrid on its groundbreaking BEET (Boston Spa Energy Efficiency Trial) initiative which uses data from customers’ smart meters to optimise voltages on the networks – potentially shaving £20 off average bills. The company also believes it could cut carbon emissions by up to two million tonnes a year, if applied nationally: the equivalent of removing 200,000 cars from the road.

By gathering and analysing information from smart meters, BEET enables Northern Powergrid to adjust voltages safely across the grid to optimum levels. Customers do not have to do anything or sign up for the service, as it works automatically ‘behind the meter’ and ensures service as normal. People with smart meters that display voltages can see that they are at optimal levels. And those who do not have smart meters also benefit, because the data is used to optimise voltages across the whole local network.

Northern Powergrid, plans to roll BEET out to around 80% of its 3.9 million customers by 2033 – and share learnings freely, so it can be adopted by fellow distributors across the UK and globally.

Voltage control for the renewables world

BEET and CLASS prove that controlling voltages with smarter technologies can be a win-win for network operators, consumers and the environment, because uncontrolled voltages are a tremendous waste of energy and money. Reaching for carbon-intensive backup generation as the primary method to keep the system in balance is also expensive and produces unnecessary emissions.

Ultimately, the technologies already exist to solve some of the biggest challenges facing the grid. DNOs need to be empowered with tools that enable them to manage voltage control and successfully connect more renewable generation sources to the grid, together with more electric vehicles and heat pumps, without having to spend billions on rebuilding our electricity infrastructure.