Software defined power grid

Read an article this past week in IEEE Spectrum (The Software Defined Power Grid is here) about a company that has been implementing software defined power grids throughout USA and the world to better integrate and utilize renewable energy alongside conventional power generation equipment.

Moreover, within the last year or so, Tesla has installed a Virtual Power Plant (VPP) using residential solar and grid scale batteries to better manage the electrical grid of South Australia (see Tesla’s Australian VPP propped up grid during coal outage). VPP use to offset power outages would necessitate something like a software defined power grid.

Software defined power grid

Not sure if there’s a real definition somewhere but from our perspective, a software defined power grid is one where power generation and control is all done through the use of programatic automation. The human operator still exists to monitor and override when something goes wrong but they are not involved in the moment to moment control of which power is saved vs. fed into the grid.

About a decade ago, we wrote a post about smart power meters (Smart metering’s data storage appetite) discussing the implementation of smart meters for home owners that had some capabilities to help monitor and control power use. But although that technology still exists, the software defined power grid has moved on.

The IEEE Spectrum article talks about a phasor measurement units (PMUs) that are already installed throughout most power grids. It turns out that most PMUs are capable of transmitting phasor power status at 60 times a second granularity and each status report is time stamped with high accuracy, GPS synchronized time.

On the other hand, most power grids today use SCADAs (supervisory control and data acquisition) to monitor and manage the power grid. But SCADAs only send data every 2-4 seconds. PMU’s are also installed in most power grids, but their information is not as important as SCADA to the monitoring, management and control of most (non-software defined) power grids.

One software defined power grid

PXiSE, the company in the IEEE Spectrum article, implemented their first demonstration project in Hawaii. That power grid had reached the limit of wind and solar power that it could support with human management. The company took their time and implemented a digital simulation of the power grid. But with the simulation in hand, battery storage and a off the shelf PC, the company was able to manage the grids power generation mix in real time with complete automation.

After that success, the company next turned to a micro-grid (building level power) with electronic vehicles, battery and solar power. Their software defined power grid reduced peak electricity demand within the building, saving significant money. With that success the company took their software defined power grid on the road to South Korea, Chile, Mexico and a number of other locations the world.

Tesla’s VPP

The Tesla VPP in South Australia, is planned to consists of up to 50K houses with solar PV panels and 13.5Kwh of batteries, able to deliver up to 250Mw of power generation and 650Mwh of power storage.

At the present time, the system has ~1000 house systems installed but even with that limited generation and storage capability it has already been called upon at least twice to compensate for coal generation power outage. To manage each and every household, they’d need something akin to the smart meters mentioned above in conjunction with a plethora of PMUs.

Puerto Rico’s power grid problems and solutions

There was an article not so long ago about the disruption to Puerto Rico’s power grid caused by Hurricanes Irma and Maria in IEEE Spectrum (Rebuilding Puerto Rico’s Power Grid: The Inside Story) and a subsequent article on making Puerto Rico’s power grid more resilient to hurricanes and other natural disasters (How to harden Puerto Rico’s power grid). The later article talked about creating micro grids, community PV and battery storage that could be disconnected from the main grid in times of disaster but also used to distribute power generation throughout the island.

Although the researchers didn’t call for the software defined power grid, it is our understanding that something similar would be an outstanding addition to their work there.

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As the use of renewables goes up and the price of batteries decreases while their capabilities go up over time, more and more power grids will need to become software defined. In the end, more software defined power grids with increasing renewables power generation and storage will make any power grid, more resilient and more fault tolerant.

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