Battery Energy Storage Systems (BESS) are playing an increasingly important role in modern power systems, particularly in the context of renewable energy and grid balancing. With that in mind, Paul Brickman, Commercial Director at Crestchic Loadbanks, explores the role of BESS and the importance of testing.

But first, for the uninitiated, what do we mean by BESS? In simple terms, a BESS consists of one or more batteries that store electrical energy for use at a later time. This stored energy can then be drawn upon when required, to meet demands for power across different applications, including electricity grids and microgrids, electric vehicles, backup power, and solar power installations.

The role of BESS (Battery Energy Storage Systems) in grid balancing  

As the UK continues its transition to renewable sources of energy, grid balancing has become an increasingly important focus for operators. To meet the demand from homes, businesses and critical infrastructure up and down the country, levels of power generation, including voltage and frequencies, must be managed so that they are exactly equal to levels being used. 

In fact, the UK power network operates at a frequency of 50 Hz. Even a 1% deviation from this has the potential to damage equipment and infrastructure, reducing the energy system’s resilience to sudden changes in frequency, which can, in turn, lead to temporary blackouts.

When harnessing natural sources of power, which are reliant on the wind blowing and the sun shining, managing a stable and constant supply can be more challenging. While the risks of undersupply are, arguably, more obvious, oversupply can also be a problem. Indeed, lockdown has shown us that we cannot always easily predict demand patterns. 

BESS has an important role to play in this grid-balancing conundrum. When excess electricity is available in the grid, such as during times of low demand or high renewable energy generation (e.g., sunny or windy days), the BESS charges its batteries. Once charged, the BESS can be used during periods of peak demand, or when renewables are not producing sufficient power. In this scenario, the BESS discharges the stored energy from the batteries back into the grid. This helps to balance supply and demand, reducing strain on the grid and enhancing grid stability.

BESS (Battery Energy Storage Systems) and the energy transition 

We’ve already covered the topic of grid balancing. However, it is important to note that using BESS not only balances the grid by providing quick-response energy injections or absorptions, but it also opens the doors for more reliable and stable integration of renewables. Perhaps more crucially, using BESS to meet peak electricity demand periods avoids the need to rely on fossil fuel power plants during such times. In certain situations, BESS can also serve as a backup power source in case of grid failures or emergencies.

BESS (Battery Energy Storage Systems) reliability and the need for testing 

As technology advances and costs decrease, BESS is likely to play an even more significant role in the future of energy storage and distribution. However, when connecting any power source to the transmission network, it is important to ensure that it is safe, reliable, and capable of effectively supporting the grid. Testing is an essential step to ensure that the BESS operates safely, efficiently, and in compliance with relevant regulations and safety standards. 

Load banks are essentially artificial loads that can be used to simulate an electrical load under test conditions. While load bank testing is not a mandatory requirement for all BESS installations, the benefits by far outweigh the risks – allowing users to: 

Energise the new connection line under load: Engineers can use a loadbank to simulate the electrical load that the power line that connects the BESS to the grid would experience during normal operation. By drawing power off the grid and energising the connection line, engineers can verify the operational integrity of the connection before it is connected to the network. 

G99 Compliance: In the UK, the connection of electricity generating facilities to the grid is regulated by the Grid Code. G99 refers to the engineering recommendation issued by the UK’s National Grid Electricity System Operator (ESO) for the connection of energy storage systems to the electricity grid. To comply with G99, the power generating module must be connected to a suitable test supply, grid simulation set or load bank as part of the test. 

Verify the operational integrity of the system: Once the line has been energised, the loadbank can be used to test BESS system components and connections, including the automatic transfer switches, transformers, and circuit breakers. 

In summary, using a load bank is a proactive measure to ensure the BESS’s proper functioning, safety, and optimal integration with the grid. By conducting thorough testing before grid connection, potential risks and issues can be addressed, ultimately protecting the grid from disruptions and contributing to overall grid reliability.