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Losses Management

It should be noted that the dependency on customers’ demand and levels of generation is outside of DNO control, but the National Grid approach to reducing losses can be split into a number of main areas: -

Understanding & Monitoring

It is crucial to the success of National Grid’s attempts to reduce losses that there is a comprehensive understanding of the subject. This means understanding the causes; their relative magnitude; where the losses are occurring on the network and what effect any mitigating actions would have.
National Grid’s most powerful tool in understanding losses is network modelling. This can create computer simulations of the network which show where losses are occurring. These simulations can also be used to determine the effect of future changes on the network operation and performance. This allows National Grid to assess what will happen if demand increases in the future, or what will happen if particular assets are changed.

The current smart-meter rollout will completely change how it’s possible to monitor the network. When the rollout is complete in 2020, there will be meter data coming from every customer as well as regular monitoring points across the network. At present, National Grid Electricity Distribution have monitoring points on the higher voltage parts of the network, but no real-time data is recorded for the lower voltages, so the understanding was limited. Smart-meters will provide comprehensive ‘real-time’ data, which should make it more straightforward to identify any areas of high loss.

Asset Replacement

The most clear-cut way to reduce losses is by replacing cables and transformers. Some of these maybe either old or less efficient assets which upgrading these to more efficient stock can substantially reduce losses. However, installation costs are often high, so generally upgrades are made when the equipment needs replacing anyway. To ensure these upgrades are cost effective, cost benefit analyses is carried out on each unit: assessing the load on the unit and thus calculating the cost of the losses it produces. In addition there is a need to ensure that all standards used to procure equipment / assets needs to take into account the need to reduce the losses and any other regulatory issues.


The variable losses in cables can be reduced by using cables with larger cross sectional areas, which also increases their capacity. 

Endeavour to site substations as close to the load / generation as possible thus reducing circuit lengths. 

Ensure that the equipment / asset standards are up to date and meet all requirements.

Network Operation

Imbalance is found on all parts of the low-voltage (LV) network due to customers who use one or two phases having different load consumptions. On the high-voltage (HV) network, imbalance is due to the uneven distribution of single-phase transformers or two wire spurs and different loads on each phase for three-phase customers. The most obvious way to reduce phase imbalance is to carefully balance the aggregated load on each phase, but as customer consumption is not always predictable and varies at different times of day, this can be difficult.

Proper balancing of voltages and power flows across the distribution system will ensure efficient integrations of distributed generation and low carbon technologies within the electricity network. 


National Grid takes on a number of innovation projects every year. Below is a sample of the ones which are related to losses. For more information on National Grid Electricity Distribution innovations, visit the innovation section of the website or read our innovation strategy.

LV Templates

The LV Templates project setup a highly monitored network in South Wales to see if substations could be characterised into a number of ‘templates,’ which could be used to describe the behaviour of other substations. South Wales was chosen as it has a high density of renewable generation. The project found that 82% of substations fitted one of the templates constructed.

The project also investigated voltage reduction. Although it is generally beneficial to run at a higher voltage to reduce the load, when voltage reductions are made whilst keeping the load fixed, losses can be reduced as the overall power flow is reduced. The project found this was beneficial and a voltage reduction of 0.88% has been carried out across our entire LV network.

Closedown Report

Losses Investigation

The Losses Investigation project aimed to obtain more data on losses on the LV network. This part of the network is not normally monitored, but it is an area where losses are quite high. To investigate them more carefully, the project setup a fully monitored area of the LV network, to investigate where losses occur. The investigation is concerned with determining the best methods for measuring and calculating losses but when it is complete, it will provide information on where the losses are occurring as well.

Progress Report


This project was also looking to balance power flows, using automated systems. A power flow forecasting tool was created, which used 48-hour weather forecasts to help predict loading. The project also developed a flexible power link, which allowed for power flow to be transferred to another area of the network, to reduce peak loads. The FPL is currently being developed and will be installed on to parts of the 33kV network in 2018.

Progress Report

Management of Electricity Distribution Network Losses 

Imperial College and Sohn Associates have worked together on an IFI-sponsored project which has examined the opportunities for moving further towards loss-inclusive network operation and design. The work has been conducted in collaboration with UK Power Networks (UKPN) and National Grid Electricity Distribution (NGED). 
The project has been designed with the objective of developing new knowledge and presenting information on network losses and low-loss design which can both inform the regulatory process in and can assist DNOs with their consideration of losses in network management. 
This report describes the studies which analyses the nature of losses, their magnitude and the economic justification for loss-inclusive network design. 
This project has positively informed and influenced National Grid’ long term plan to discover new knowledge of network losses and to develop network policies, standards and network designs for future networks. 
Management of Electricity Distribution Network Losses – Final Report 
Management of Electricity Distribution Network Losses – Report Appendices 


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