Outcomes, Insights, and Best Practices from IIC Testbeds: Microgrid Testbed
be the size of an 18-wheeler cargo container. The Microgrid Testbed housed at the Industrial IoT Lab, realistically mirrors future end deployments: Putting all the equipment in a rack, connecting the equipment with a single Ethernet cable, and having all the equipment be TSN-compliant on a small scale.
Lab Status
The Microgrid Testbed lab in Austin is simultaneously in a state of completion and development. When Jamie Smith, Director of Embedded Systems, National Instruments, opened the lab in February 2017, he made the tongue-in-cheek comment,“ Nothing in the lab is finished,” to denote that it is meant to be a working lab, and all the testbeds housed within are meant to be working testbeds. So, the testbed team goes to IIC meetings and networks with other people to discover whether there could be someone with tablet technology or some other software technology, etc., wanting to contribute to the testbed.
Utility experts are now being invited to the lab to witness all the parts of the solution currently being tested. The testbed team asks the utility experts for validation that the innovations of the testbed help solve the real-world problems. Those conversations have already begun and continue to be evolving discussions, probing and identifying other problems the utilities would like the testbed team to solve and move to deploy those solutions. The team is actively working toward moving to a field deployment with other partners’ involvement.
GRID RE-SYNCHRONIZATION
One of the wrinkles of having a microgrid is, because of the way inverters are designed today, even when running from storage, it becomes difficult or impossible to reconnect to the main grid. It can happen with today’ s technology but it is not guaranteed and when it does happen, is not a fully controlled maneuver.
When the main grid goes down, the microgrid disconnects and continues to run. There may be a short blackout to those on the microgrid, but because it is selfsufficient, it starts up again rather quickly. However, when it is time to reconnect to the main grid, it becomes complicated. Because there is no active control over the frequency and voltage on a microgrid, the frequencies between the main grid and microgrid need to match by happenstance to reconnect. If that occurs, then there is technology on the market today that will make the connection and both the main and microgrid are in sync. If the two grids are not on the same frequency then protection systems prevent the re-connect and the microgrid will run until storage( batteries) are depleted, blackout again, and then reconnect. The inconvenience of two blackouts is another microgrid problem that new IIoT technology can help solve.
STANDARDS
TSN is the technology enabling the synchronization required in the Microgrid Testbed to run a stable grid on 100 % inverter sourced power. National Instruments and Cisco are both heavily involved in the TSN standard development, both from the IEEE side as well as with the Avnu Alliance. Avnu is an organization working on the promotion and usage of TSN.
DDS is an open-communication protocol that is used to implement machine to machine communication at the edge where
- 38- September 2017