Yuasa lithium-ion batteries have been used in a successful trial to evaluate the concept of office Virtual Power Plants. Working with energy management company Kiwi Power, consultant Swanbarton Ltd and Riello (UK), Yuasa LIM batteries were installed in an IT standard 19inch rack with the same floor loading as a filing cabinet.
Uninterruptible power supplies (UPS) have become an essential, although largely invisible, element of IT infrastructure. The reliability and efficiency of UPS systems have improved consistently during the last 30 years but the fundamental services, of power quality and continuity, have remained the same. The current thrust for de-carbonisation of electricity networks presents new challenges and opportunities for the UPS industry.
Intermittent renewables, such as wind and solar, provided 14.2% of UK electricity in 2015. Global experience indicates that electricity network instability requires some form of balancing facilities once the share reaches 20%. National Grid Plc is expanding ancillary service contracts to achieve this. New plants for Short Term Operating Reserve, and Frequency Response services are proliferating, together with TRIAD contracts, which will see many large consumers operating their diesel back-up generators this winter.
Organisations must be able control power flows of many megawatts to provide services to National Grid. For example, electricity storage is recognised as the only viable technology for the new Enhanced Frequency Response market, it will be provided by dedicated grid connected batteries charging or discharging at 20-50MW. An alternative resource could be the 4GW of stored power embodied in the UPS already installed in UK. To participate in this new business opportunity UPS will need to be re-powered with deep cycling batteries and be able to work as an aggregated array to provide the required scale.
Energy management company Kiwi Power and consultant Swanbarton Ltd were funded by Innovate UK to evaluate the concept of office Virtual Power Plant (VPP) in 2015. Yuasa Battery was selected as the system supplier working in partnership with Riello (UK) Ltd. Since January 2016 a system has been operating in Kiwi Power’s London office supporting up to 20 staff with power in the range from 5-12kW. Because of the high energy density of the Yuasa lithium ion batteries a 25kWh system could be mounted in a first floor office, in a 19inch rack with the same floor loading as a filing cabinet.
The UPS is a standard MCM20NP model manufactured by Riello. Additional commands were added to its’ firmware to provide VPP operating modes;
• Discharge mode – Office load is removed from mains supply and supported by battery.
• Hold mode – Office load is supplied from mains and the battery remains in static state of charge.
• Charge mode – Office load is supplied from mains while the battery is recharged at a programmable rate.
The normal UPS mode is restored immediately in any event of mains failure, to support the office load.
The choice of operating mode is made by a Micro Grid Storage Manager (MGSM) developed by Swanbarton. This collects information on the National Grid status, battery state, local load and aggregated load conditions.
Peter Stevenson, Senior Technical Co-ordinator at Yuasa Battery Europe Ltd said: “The system has been operating seamlessly to vary the demand of Kiwi’s office, as a virtual power plant, in a way which is transparent to office operations. By using off the shelf and highly developed UPS hardware Kiwi and Swanbarton have been able to focus on the key commercial aspects of how to capture the rapidly growing revenue opportunities for energy storage. With the right App in place your UPS can become a bank account for energy trading as well as an insurance policy against power failure.
“Yuasa lithium ion products are ideally suited to energy storage applications. They are based on robust lithium metal oxide chemistry with premium cycle life and high power capability. This allows them to capture surplus power whenever it is available and to supply the load very efficiently. More than 95% of the charging energy can be recovered by the load, compared with 80% efficiency for lead acid batteries. The battery can provide many thousands of deep discharges and never needs to be fully charged. Yuasa supplies lithium ion products in many formats including plug and play cabinets ready for immediate connection to your UPS.”
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