The stereotypical view of a uninterruptible power supply (UPS) as the big, bulky and inefficient black box sat in the corner of your IT room is most definitely a thing of the past.
UPS technology and design has come on in leaps and bounds over recent years, leading to huge improvements in operating efficiency and functionality in a vastly reduced footprint, especially in large-scale installations such as data centres or telecoms, industrial, and retail environments.
Transformer-free and modular solutions
Typically, the most common UPS design was transformer-based, where the power flows via the rectifier, inverter, and transformer to the output, with the transformer used to step up the AC voltage levels.
While transformer-free alternatives have been around since the 1990s, they’ve really grown in popularity over the last decade or so as the technologies became more mainstream.
They operate in a similar way but use IGBT transistors capable of dealing with high voltages, eliminating the need for a step-up transformer after the inverter.
Removing the transformer leads to several benefits. Physically they are smaller and lighter than transformer-based models. They deliver higher energy efficiency and generate less heat, so require less cooling too.
While transformer-based UPS are still the preferred choice for installations requiring galvanic isolation, such as industrial processing, transformer-free models are now the norm for power ratings below 10 kVA and are also available up to around 300 kVA at the higher end of the spectrum.
Then there’s been the growth of modular UPS as opposed to the typical monolithic units. Modular solutions offer simple ‘pay as you grow’ scalability – at initial installation you closely mirror your load requirements, and if you need more capacity in the future, you just add extra power modules as and when the need arrives.
Modular solutions reduce the risk of expensive oversizing so help to control your upfront capital costs. And because they deliver a high power density in a compact footprint, they help to maximise valuable floor space. While because each power module is hot-swappable, you’re guaranteed downtime-free maintenance during any service visits.
Smart grid ready
Another key area of progress – and one likely to become increasingly important as we transition towards a net zero electricity network – is the rise of smart grid-ready UPS systems.
Thanks to advances in management and monitoring software, communications protocols, and battery technologies, some UPS can communicate with local power networks. Then depending on the real-time conditions, they either draw electricity from the grid or push power from the batteries back in to help balance supply with demand and ensure a stable frequency.
Common applications for smart grid-ready UPS include peak shaving, which in effect uses the batteries to limit how much electricity you need to draw from the mains supply.
Then there’s frequency stabilisation, such as National Grid’s Firm Frequency Response scheme. In practice, if the frequency drops below the safe limit of 50 Hz, stored battery power pushes back into the grid, or if the frequency goes above 50 Hz the UPS draws electricity into its batteries to pull the frequency back down.
Such advances have the potential to transform a UPS from an essential but pretty reactive piece of kit (i.e. waiting to kick-in when there’s an issue with the electricity supply) into a dynamic ‘virtual power plant’, particularly in large-scale installations.
Upcoming trends
Looking to the future, as UPS manufacturers push for even higher efficiencies, one of the emerging trends is the wider use of silicon carbide semiconductors.
These are far smaller and lighter than the silicon-based components that have typically been used in UPS production. They also produce less heat, which in turn reduces the need for cooling.
The higher efficiency of the silicon carbide components significantly reduces the energy needed to run the UPS and increases its overall performance, enabling it to achieve efficiency around 98% whilst operating in maximum protection online mode.
That’s equivalent to the efficiency ratings you only tend to see when the UPS is running in various ‘Eco’ or ‘economy’ modes, where any energy saving always goes hand in hand with a trade-off in reduced protection.
As the availability of silicon carbide improves, the UPS systems of tomorrow will be able to deliver greater capacity at a higher operating efficiency in a smaller footprint than even today’s most advanced solutions.
Last week, Ryan Jones highlighted the four biggest myths about UPS and explained how to tackle those myths. Find out more about Riello UPS here.