Achieving Operational Flexibility with Voltage Control

Using voltage data down to the consumer level is essential for grid optimisation and operational flexibility in the new era of intermittent generation and fast-changing user demand.

Power grids were designed and built many decades ago to accommodate centralised generation with largely predictable customer demand and predictable network voltage profiles. However, existing infrastructure now needs to be adapted to cope with demands of a low-carbon era with increasingly dynamic supply and demand.

For example, one of the biggest challenges facing power grids is the monitoring and control systems that were implemented to manage high-voltage (HV) parts of the grid. Many are no longer fit for purpose. And as network complexity has increased, fluctuations in voltage can have significant repercussions—high voltage can be dangerous and low voltage (LV) can be disruptive—with both having significant cost and environmental impacts.

Typically, high voltages cause higher losses and wastes energy, increasing electricity bills and carbon emissions, and causing acceleration of equipment ageing and potentially premature failure. There are also customer service impacts. Consumers rightly expect suppliers to comply with statutory voltage regulations, and low-carbon technology providers should be able to connect to the grid as efficiently as possible.

Whole-System Approach

What’s needed now is a “whole-system approach” to voltage control that allows network operators to adapt the current system and reinforce power grids to cope with new demands and support a low-carbon future. Voltage control systems have existed in substations for many decades. The current generation of technology is at the heart of Electricity North West’s CLASS (Customer Load Active System Services) initiative, which enables it to participate in the balancing market by amending system voltages to control electricity demand. CLASS uses automatic voltage control (AVC) relays to increase or reduce voltages by amounts that are imperceptible to consumers to amend load demand (Figure 1). The relays are linked to a control centre, which uses an advanced network management system to respond to grid frequency changes caused by the imbalance between energy demand and generation.

Moving forward, the advanced functionality that voltage control systems offer will be at the heart of creating an increasingly dynamic grid. Particularly, if they are adapted to incorporate “Wide Area Control,” which utilises measurement data from all parts of the grid including “at the edge”—in homes and business in the LV network where electricity is consumed.

The Power of Local Data

In many cases at present, network operators only learn of voltage issues when customers complain, for example, when an electric vehicle (EV) user in an area with high solar panel uptake cannot charge their car because voltages are too high for inverter systems to handle. With a whole-system approach, voltages can be optimised using smart meter data to identify areas where this kind of issue exists.

Existing voltage control functionality for the grid is generally implemented with measurement and control actuation in the same location (normally a substation). However, by including the “extended voltage feedback system,” data collected directly from the consumer end of the network can supplement substation measurement data to provide a more accurate assessment of network requirements.

For instance, Northern Powergrid’s groundbreaking Boston Spa Energy Efficiency Trial (BEET) innovation project uses data from customers’ smart meters to optimise voltages on the network using existing voltage control systems in HV substations. Northern Powergrid believes BEET could shave more than£20 off average bills and cut carbon emissions by up to two million tonnes a year, if applied nationally, the equivalent of removing 200,000 cars from the road. It plans to roll BEET out to about 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.

A Whole-System Approach Vs. Patchwork Fixes

The goal of a whole-system approach to voltage control is to enable operators to respond flexibly and instantaneously to the fluctuations caused by rapid changes of input from intermittent generation, together with sharp peaks and troughs in customer demand. Products and services that can deliver total voltage control across the LV and HV layers of the grid are constantly expanding and evolving. AVC options are moving from hardware-based to digital. Artificial intelligence, improving algorithms, and enhanced communications are making whole-system voltage control easier.

But we also need to maintain and update the thousands of legacy transformer assets, many of which have been managing voltages on the grid for more than 50 years, by adding new sensor and communications technologies to make them part of a fully integrated system that is equipped for the new era of super-dynamic supply and demand. Integration of digital technologies with legacy assets can modernise and future-proof the network, delaying replacement and saving money. Crucially, it can ensure whole systems are managed more intelligently, to deliver greater reliability of service, regulatory compliance, and lower costs, together with accommodation of more distributed energy resource connections, more efficient load balancing, and lower carbon.

—Jon Hiscock, PhD is CEO of Fundamentals Ltd., a power systems technology specialist.