T&D World Magazine
Smart grids can support bidirectional power flow
Smart grids can support bidirectional power flow

Automatic Circuit Reclosers Help Connect Renewable Energy Sources to Smart Grids

Key developments in protection and monitoring functionality such as synchrophasor technology will allow utilities to use ACRs––instead of expensive substations––to connect distributed renewable energy sources such as wind and solar to tomorrow’s smart grids.

NOJA Power has highlighted in a white paper how the next generation of Automatic Circuit Reclosers such as future versions of its OSM series ACRs, will lower the cost and simplify connection of renewable energy generation to smart grids. Renewable energy is forming an increasing component of the world’s generation capacity as nations step up their effort to limit carbon emissions.

Heads of government have reached an agreement at the 2015 UN climate change conference in Paris, France, to reduce carbon emissions in an attempt to limit the planet’s average temperature rise to 1.5 C. The Paris agreement includes financial (US$100bn ($139bn) a year by 2020) and technological assistance for developing countries to help them bypass fossil fuels and move straight to renewables. As a result of this, and previous carbon-reduction initiatives, renewable generation is set to rapidly increase around the world. Australia, for instance, already has the highest penetration of grid-connected, rooftop photovoltaic (PV) systems anywhere on the globe; in some localities of Brisbane, Qld, for example, 60 percent of domestic customers have installed some PV capacity.

Integrating widespread renewable generation into existing distribution grids––which were originally designed to accommodate huge power stations sending power in one direction over transmissions lines to local substations which stepped down the voltage for distribution across local networks­––is very difficult. Smart grids––advanced, computerized electricity distribution networks––are better suited to the distributed nature, bidirectional power flows and precise monitoring and control demanded by renewable generation. Nonetheless, integrating RE generation into a smart grid is still tough; challenges include building expensive new infrastructure, and dealing with the voltage variability, power quality, and grid protection issues that RE generation creates.

Modern ACRs such as NOJA Power’s OSM series––as fundamental components of smart grids­­––already provide solutions to many of these challenges. For example, the ACRs perform voltage measurements on all six bushings, current measurement on all three phases and provide extensive power quality and data logging capability as well as many of the switching, bidirectional protection, control and communication capabilities required to integrate RE generation into the electricity grid.

However, developments are underway to enhance functionality to provide a comprehensive solution. For example, NOJA Power is developing synchrophasor technology for its products. The technology has become increasingly relevant since a 2004 U.S.-Canada investigation into blackouts recommended the use of synchrophasors to provide a real-time, wide-area grid visibility.

A key application of the technology is “islanding” detection. Islanding occurs when part of a network is isolated from the rest of the grid but continues to operate because it has a local source of generation (such as an RE source). Such a phenomenon is undesirable because it can be hazardous and can result in poor power quality potentially damaging utility assets. Synchrophasor technology provides a means for detecting islanding under nearly all load and generation conditions.
 
“The next generation of NOJA Power auto reclosers will deliver a cost-effective, reliable means for utilities to connect, monitor, control and protect renewable generation as part of future smart grids,” explains Neil O’Sullivan, NOJA Power’s Managing Director. “Notably, the ACRs will be equipped with synchrophasor technology to detect early signs of islanding and switch to change generation sources or shed loads to prevent an island forming.

NOJA Power’s OSM series ACRs are fundamental elements of smart grids and provide a comprehensive suite of automation features. The OSM series has been fully type-tested by independent laboratory KEMA in the Netherlands to ensure long life and reliability under the harshest environmental conditions. Since their introduction, the OSM series ACRs have been installed by utilities in over 84 countries around the world. (See “About the NOJA Power OSM series” below.)

NOJA Power has produced a white paper entitled “Integrating renewable energy sources into smart grids using Automatic Circuit Reclosers”, which details how its ACRs can be used to economically connect renewable energy generation to smart grids. The white paper is available from the company’s website, www.nojapower.com.

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