• E. Estelles

Benchmarking Energy Usage at SSEN Substations

Power grids represent vital infrastructure in modern society: when large amounts of electricity must be delivered from power plants to homes and businesses, the grid is the fastest and most efficient option. However, power networks are not perfect, and they have losses like any electrical system. Keeping these losses as low as possible is in the best interest of energy companies, since they represent power that is generated but not billed.

Logic Energy has been working with Scottish and Southern Electricity Networks (SSEN) to benchmark energy consumption at substations. The study has the goal of analysing how energy usage is affected by their design features, building condition, and external factors such as the weather. The five substations considered in the study are located in different regions of Scotland, including the Highlands.

The study considers the individual energy consumption of heating equipment, lighting fixtures, and other substation systems. Logic Energy has also been monitoring key weather variables like temperature and relative humidity, to analyse their impact on energy consumption. Based on the results of this study, SSEN will develop a plan to reduce their non-technical losses.

Understanding Technical and Non-Technical Losses

Reducing grid losses is a top priority for power companies, as mentioned above, since they represent electricity that is not being sold. Achieving 0% losses is impossible, since even the most efficient equipment dissipates power, but a well-managed grid should have minimal losses. Annual transmission losses in the UK are typically below 2%, but this number can be misleading:

  • Considering that the UK consumes 330 terawatt-hours per year (330 billion kWh), a 2% loss represents 6.6 TWh (6.6 billion kWh).

  • Since the typical household consumption is 3,100 kWh per year, these losses are equivalent to the consumption of over two million homes.

Even a slight reduction of the transmission loss percentage can unlock enough electricity for thousands of homes. However, the first step to reduce grid losses is identifying them, and there are two main types: technical and non-technical.

In simple terms, technical losses represent all the energy dissipated by the grid while delivering electricity to the point of use. For example, the heat dissipated by power lines and transformers is considered a technical loss. On the other hand, non-technical losses represent energy that is used but not billed. This can be the result of metering errors, unidentified consumption, or even theft.

Substations have both technical and non-technical losses. They have power conversion equipment that dissipates energy, and building systems that consume unmetered electricity. Each type of loss requires a different strategy:

  • Power conversion losses (technical) can be reduced by replacing transformers and other substation equipment with newer and more efficient units.

  • The unmetered consumption of building systems (non-technical) can be reduced with energy efficiency measures, like in any commercial or industrial facility.

Using Logic Energy monitoring systems, SSEN will benchmark energy consumption in substations of different ages and constructions. Consumption will be analysed individually for each building system, identifying the best opportunities to save energy without compromising operations. The benchmarking results could be applied at a larger scale, reducing the non-technical losses of any SSEN substation.

Transmission and distribution losses also have an environmental impact, especially in grids that rely on fossil fuels for most of their power generation. The reduction of technical and non-technical losses can complement the use of renewable sources, and power grids can be decarbonised at a faster pace. Renewable sources are on the rise in the UK, according to the Digest of UK Energy Statistics:

  • Their output reached 134.6 TWh in 2020, representing 43.1% of total generation.

  • For comparison, fossil fuels generated 117.8 TWh that same year.

The RIIO-T2 Plan: SSEN Goals for the 2022-2026 Period

SSEN has established five ambitious goals for the five-year period between 2022 and 2026, which are part of the RIIO-T2 Plan:

  1. Transporting renewable electricity for 10 million homes.

  2. Reaching 100% network reliability for homes and business.

  3. Delivering all connections on time.

  4. Reducing greenhouse gas emissions by one-third.

  5. Achieving £100 million in efficiency savings with innovation.

Substation benchmarking can contribute directly to goals #4 and #5. With a reduction of non-technical losses, SSEN can avoid the emissions and costs associated with those losses. Monitoring systems can also reveal performance issues that may affect the reliability of SSEN power networks, contributing to goal #2.

In December 2019, SSEN published their transmission losses strategy in a detailed document. They presented a case study for the Tealing 275 kV substation, where losses were analysed in collaboration with Edinburgh Napier University. SSEN determined that the substation was losing 192 MWh/year (192,000 kWh/year), equivalent to the average consumption of 62 UK homes.

  • The study identified a savings opportunity of 109 MWh/year, where 41 MWh/year could be saved with relatively simple measures.

  • The measures proposed in the study included intelligent lighting controls,luminaire replacements, and building envelope upgrades to improve thermal performance.

SSEN and Edinburgh Napier University extrapolated the potential savings for the entire substation fleet, and they estimated a savings opportunity of 2 GWh/year (2,000,000 kWh/year). The study also proposed onsite solar generation as a way to compensate for substation losses that cannot be eliminated.

The growth of renewables is concentrated in northern Scotland, while most consumers served by SSEN are located to the south. To keep up with renewable generation, SSEN must keep their networks in optimal condition, operating with high efficiency and reliability. According to the Future Energy Scenarios (FES), Scotland could reach a renewable generation capacity of around 31GW - 40GW by 2030, up from 12.3GW reported by the Scottish Government in December 2021.

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