Virtual power station project maps distributed generation

"The virtual power station is about lots of small renewable energy devices working together," Daniel Rowe, engineering analyst with CSIRO Energy Technology told pv magazine, "so that the product is bigger than the sum of the parts."

Scientists from CSIRO are working with a local council and residents in the state of New South Wales on the Virtual Power Station Technology Trial. It involves installing a "little black box" to volunteers’ inverters, which transfer electricity output data back to the CSIRO’s central computer. The data is then uploaded onto a website where homeowners can monitor their system’s output.

The second outcome of the project is to help homeowners better understand and relate to their photovoltaic system’s output, and therefore regulate and synchronize their own power usage accordingly.

The major aim of the project is to develop a system whereby, in theory, with diffuse power generation from a multitude of photovoltaic arrays, systems can be linked to form a virtual power station. Grid operators and utilities could then integrate battery storage to "smooth" electricity production peaks and in accordance with demand. "Using the power that these devices generate, you can aggregate that together and then use storage devices to make up any gaps that you may have or provide services for the electricity grid," explained Rowe.

Another benefit, continued Rowe, is that with photovoltaic arrays spread across some distance, the communication devices can also be used as a source of weather prediction data. "You can see weather transiting across the system, which can allow you to change your control strategy and maybe export a bit of power from your batteries or save a bit more for later."

Peace of mind

At present, there are fears amongst utilities and grid operators that the rapid increase in residential solar installations that have gone up across the suburbs of Australia, could have an adverse impact on the aging grid infrastructure. In 2011, over 700 megawatts of photovoltaic capacity was installed, largely by householders.

"One of the things that gets utilities worried at the moment, is that they’ve got all of these solar panels spread out across their grid and they don’t know what they’re doing," continued Rowe. Using the data from a virtual power station system, storage or backup generation technologies – like gas boosters – can then be used to absorb periods of high production of make up for it when it decreases. "You can also do some funky things like load control, which means turning off non-essential devices. And that isn’t noticed at all by the end user."

In CSIRO’s technology trial, 20 sites have been chosen to provide the data, across Lake Macquarie City Council properties and homes in the area. Nineteen of the sites are only monitoring locations and one has been equipped with storage capabilities. The researchers can then instruct this site when to charge or discharge the batteries.

The sites communicate using the mobile phone network, "but in the future we see this using the internet network," said Rowe. Australia is, at present, investigating the installation of ultra-fast broadband technology.

The project has been running for three years and the technology trial has been in place for the past year. One of the first outcomes that has been observed by the researchers is that participants have been able to stay more connected with their own array, see their daily output and compare it with other arrays on the virtual power station network. "An interesting outcome has been that one person found that there was a problem with their inverter and it wasn’t exporting any power at all!"

Rowe believes systems like the virtual power network could be installed more widely in homes in three to five years.