Synthetic Inertia and Microgrid Stability on Kilowatt-scale Microgrids

We’ve worked with microgrid-powered communities to pioneer synthetic inertia and microgrid control in renewable and diesel microgrids.

Just as in a megawatt-scale grid, the balance of supply and load on a kilowatt-scale microgrid must be continuously maintained. If it’s not, the frequency of the AC power changes, which can cause power reliability issues.

An off-grid system with more than one source of energy generation needs a “heartbeat” to give the other elements on the system a known frequency to lock onto. Otherwise, step changes in energy on the grid when generation sources and loads turn on and off can cause frequency instability, which can affect operation of appliances and – in worst cases – cause the grid to fail.

This is where the Deka® UltraBattery® comes in.

Thanks to its robustness and high power, the Deka UltraBattery can be used to provide the heartbeat of the power system. The system as a whole can then respond to the high power swings demanded by the microgrid while maintaining a stable frequency to support reliable power.

Synthetic Inertia and Off-grid Stability

Reliable and accurate response to the high-power swings demanded by microgrids

Deka UltraBattery: Leading the Pack

The Deka UltraBattery has already achieved the next step in energy storage – maintaining multiple demanding applications in a single installation.

Our microgrid projects use battery systems powered by the Deka UltraBattery to smooth solar and micro-hydro while maintaining the balance between generation and load to prevent the diesel generator from needing to start.

Our Ecoult UltraFlex – a 48 V battery system powered by the Deka UltraBattery – is a perfect example. In our largest Ecoult UltraFlex microgrid project – a community of dozens of houses – the Ecoult UltraFlex is just one battery system among many spread around the site, but it’s the one used to drive the heartbeat of the system.

Just as in the mains power grid, every battery and generator in the microgrid must parallel its frequency with the wider grid. But unlike mains power grids, microgrids don’t have a natural frequency produced by large rotating machines, so instead something must power a synthetic frequency signal.

Because of its high power, reliability, large capacity, and online remote monitoring, the microgrid’s designers give this task to the Ecoult UltraFlex.

The various electrochemistries dotted around the microgrid match their frequency to the heartbeat of the Deka UltraBattery that powers the Ecoult UltraFlex. It literally leads the pack.

The Benefits of a Multipurpose Battery Technology

Shipping diesel to remote sites is expensive, so microgrids must do all they can to avoid using the fallback diesel generator. Every kilowatt hour stored from the sun therefore represents a major saving.

The Ecoult UltraFlex helps to avoid generator use by remaining ever-flexible in partial state of charge and by providing “reserve tank” capability for those times when renewables simply can’t keep up with demand. This means the generator can be switched completely off, while the time required for it to start up and come to full power is always covered by the Ecoult UltraFlex. So even in the worst-case scenario, diesel runtime is minimized and the lights stay on.

The Ecoult UltraFlex also helps to manage grid frequency by storing and releasing PV-generated energy in multiple ways. For example, once the batteries are full, rather than letting “excess” PV energy go to waste the Ecoult UltraFlex stores it in other ways – for instance, as heat in water tanks for the site’s various hot water needs.

The Future is Already Here

This mix of energy generation, frequency management, storage methods, load management, and cost savings will become more and more characteristic of microgrids and even main grids in the near future.

For the Ecoult UltraFlex, powered by the Deka UltraBattery, the future is already here.