Network operational losses in comparison to other EU member states are high in the UK. Approximately 6% of electricity generated is lost each year in UK distribution networks, incurring costs in the region of £1 billion to customers. The majority of these losses occur within distribution transformers and low voltage circuits.
Cutting grid losses
In an effort to reduce these losses and improve energy efficiency, the UK government has put into a place a number of targets for the country to reach - a 16% reduction in greenhouse gas emissions, a 15% increase in the share of renewables by 2020, as well as a reduction of 176.6mt of carbon in terms of raising efficiency in the network.
UK power distributors are obligated to meet these targets otherwise they could face significant penalties. For instance, British Gas was fined £11.1 million by the regulator Ofgem over its failure to deliver energy efficiency measures on time, and power generator Drax was fined, under the community energy saving programme (Cesp), a record £28 million for failing to meet its energy efficiency obligations under Cesp.
To help Distribution System Operators (DSOs) meet these targets, Dr. Sarat Chandra Vegunta, Senior Consultant – Power Systems Solutions (PSS) at S&C Electric Europe Ltd., which covers Europe, Middle East and Africa, will be presenting three papers at CIRED 2015, an international conference and exhibition on electricity distribution, between 15-18 June. All three papers are closely related with distribution network losses reduction aspects in the UK, the reasons for these losses, and the opportunities that energy reductions give Distribution Network Operators (DNOs). The papers have been written from a UK perspective.
According to Dr. Vegunta, the papers were written in response to the growing global concern around climate change, and growing energy costs that utilities and customers are forced to grapple with. These are the two main drivers for improving electrical network efficiency. Obviously, by meeting the regulators’ targets, DSOs can also avoid the steep fines.
Reducing energy losses-a real case study
While there is scope for some conventional methods to reinforce the network with tools already on hand to replace transformers and procure more efficient transformers based on cost benefit analysis, the industry is seeking additional tools and methods for DNOs to meet EU directives, explains Dr. Vegunta.
S&C Electric recently worked with a UK utility to reduce technical losses and looked at various network interventions that could be implemented. This included several solutions which are discussed in the three papers (Distribution network losses reduction - CIRED Paper 0068; UK utility losses reduction work - CIRED Paper 0069; Substation losses reduction via redundant transformer switching - CIRED Paper 0070):
- Network reconfiguration
- Conservation voltage reduction
- Switching off a redundant transformer at the substation
- Network meshed operation
- Energy storage solutions
- Upgrading system voltage.
Dr. Vegunta says that the UK utility received Innovation Funding Incentive (IFI) funds, an incentive offered by Ofgem to enable DNOs to conduct research and identify opportunities to reduce network losses. With this funding, S&C Electric was able to conduct a year-long study and look into the impact of these network interventions to reduce losses. As part of the study, a detailed technical analysis and cost-benefit analysis was conducted.
S&C Electric found that there were two specific interventions which were very effective in reducing losses:
- The Transformer Auto Stop Start (TASS) method switches off one in a pair of transformers in selected substations to reduce fixed losses. Dr. Vegunta explains, “This involves two (one redundant) transformers operating up to a maximum of 50% load at a substation. We would switch out one of these transformers when the load falls below a cross-over point, an optimum loading point of the substation where one of the transformers is switched off, so that the losses associated with energized transformers are reduced. From this we could reduce up to 9% in the overall total losses that exist in that specific UK network. The return on investment was also quite reasonable.”
- The Alternative Network Topology method will be deployed alongside the TASS method where appropriate, to further reduce losses and maintain network supply integrity. This reduces electrical impedance of the network, thereby also reducing losses.
By combining these two methods into various options for the DNOs, they can significantly reduce network technical losses of over 31,000MWh of electricity over 45 years, worth over £40 million to Britain’s customers. This equates to savings of 6,421 tonnes of CO2.
With this positive result, the UK utility applied for funds in order to do a hardware demonstration and Ofgem gave the utility the go-ahead last year to proceed with Project LEAN (Low Energy Automated Networks) which was launched in December 2014. LEAN seeks to demonstrate new methods that can be applied to existing assets to reduce losses in the shorter term.
This consists of the two aforementioned methods. S&C Electric are currently looking into the risks of implementing the two methods.
This type of trial has never been deployed in Britain or overseas and poses an element of risk and uncertainty, which require detailed investigation and understanding before integrating LEAN into business as usual activities. However, the methods offer worthy benefits if the solution is proven. For this reason, the LEAN project is ideally suited to the aims of the Low Carbon Network Fund.