Most microgrid owners just want a smart way to control their energy mix. Here’s how Emax 2’s all-in-one innovation helps them cut through the noise
The aim of ABB’s Emax 2 all-in-one innovation is straightforward: help make the microgrid architecture for typical installations simpler and more cost-effective. Most microgrids operate at industrial plants, commercial buildings and remote communities with power requirements up to 4MW. They’re relatively small, low-voltage networks with a substation, connected to a medium-voltage mains supply.
What the facility owners want is something ready to make decisions, controlling their energy mix and keeping things moving. It’s like getting the music right at a party: you shouldn’t overthink it. We figured most just need a good DJ who can set up quickly and knows how to roll with whatever’s happening.
The idea of using less equipment and a simpler interface was just the starting point for the Emax 2 all-in-one for microgrids, however.
A breaker that listens up
Emax 2 is not like other circuit breakers. It doesn’t just detect downstream faults: it can also spot upstream faults in the medium-voltage grid. Interface protection system is the new function that uses Emax 2’s unique frequency and voltage sensing to “listen” for faults upstream of the breaker. It not only provides better protection for the plant; it also manages the islanding phase of the microgrid.
When a fault in the medium-voltage network is detected, Emax 2 opens, disconnecting the microgrid from the mains power. It then switches the microgrid into islanded mode, communicating with other breakers on the site via Ethernet connections, getting them to adapt protection profiles.
In this operating mode, when the short-circuit values at the microgrid feeders change, so do all the other circuit breaker settings. In this way, Emax 2 guarantees the selectivity and coordination between the devices in every situation, helping to ensure the plant’s continuity.
DJs know they need to get on the mic before dropping a tune that changes the tempo. You just need to tell everybody it’s coming and that’s what Emax 2 all-in-one does.
Beat the frequency shifts
When a site finds itself in islanded mode, managing the non-critical loads is as important as filtering the song requests every DJ gets. ABB’s patented, fast-load shedding function can disconnect non-critical loads like air-conditioning or pumps in a fraction of a second, so that servers or emergency lights stay on line always.
When a microgrid first enters islanded operation, its consumption is often higher than its generation. It could be consuming 1MW and only producing 500kW on site as back-up generators can typically supply 40-50% of the site’s loads.
Managing the power gap intelligently is essential. Imbalances rapidly reduce the voltage frequency and something like a 5% drop can be enough to trip the local generator’s protections with consequent blackout.
To prevent that, Emax 2 quickly spots any movements in the frequency and disconnects loads according to a priority list. Even without other meters installed in the switchgear, algorithms in the intelligent breaker can evaluate how much power needs to be shed from the loads under its supervision. The same strategy is used to manage solar generation, estimating the power based on values set during commissioning, factoring in the time of day and year with the installation’s location, field and orientation.
From the instant Emax 2 all-in-one detects the fault in the mains grid, it takes just a fraction of a second for it to put the current back on the right frequency, cutting non-essential loads. Then, using embedded logic that act as an automatic transfer switch, Emax 2 is able to bring in other local power generation sources. Like a DJ, once the beats are matched, the breaker cross-fades to the next track and the floor stays filled.
Always in synch
Even in islanded mode, when the Emax 2 circuit breaker is open, it keeps one ear on the main grid and one tuned to the microgrid, tracking the voltages and frequencies. When the main power grid is ready to come back in, the circuit breaker compares the different voltage waveforms on that grid and the microgrid.
Transient current surges can be ten times the nominal current, placing huge stresses on the microgrid’s components if the interface breaker closes without synchronism. Emax 2 aligns the waveforms’ magnitude and frequency by signalling the generator’s voltage regulator to speed up or slow down.
Once the microgrid is reconnected to the grid and back to steady-state, Emax 2 is able to perform some of its more advanced power management functions. It can proactively control load power consumption and generator production to set the amount of energy absorbed from the grid, improving cost savings by removing peaks that incur heavy surcharges.
In parts of the US and Europe, some utilities even buy back power from companies at peak times, asking selected customers to reduce their consumption for short periods. Emax 2’s simple demand response interface makes it simple to dial things down.
For most microgrids, this really is all the functionality they need. By focusing on what matters most to the majority of people, Emax 2 brings something pretty special to the party.