NOJA Power highlights how Automatic Circuit Reclosers will make it simpler and less expensive to 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.

Smart grids diagram

Smart grids can support bidirectional power flow

Electrical switchgear engineers NOJA Power today highlights how the next generation of Automatic Circuit Reclosers (ACR or “auto recloser”), such as future versions of its OSM series ACRs, will lower the cost and simplify connection of renewable energy (RE) generation to smart grids. RE 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 RE. As a result of this, and previous carbon-reduction initiatives, RE 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 RE 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, computerised electricity distribution networks––are better suited to the distributed nature, bidirectional power flows and precise monitoring and control demanded by RE generation. (See “About smart grids” below.) 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.

“The company’s auto reclosers will provide a comprehensive solution for renewable energy integration at a fraction of the cost and require much less installation and commissioning time compared to today’s expensive alternative of building a new substation each time. RE generation that’s currently economically unviable because of infrastructure cost could then become practical.”

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.au

About smart grids

Consumer backlash to rising prices, increased raw energy costs, deregulation and pressure from the environmental lobby to limit the construction of new power stations has encouraged utilities to explore the benefits of computerisation and distribution automation in order to enhance the performance of the grid. Such enhanced networks are called “smart grids”.

The implementation of smart grids includes fitting each device on the network with sensors to gather data, and adding bidirectional digital communication between the devices in the field and the utility’s network operations centre. Another key feature of smart grids is the automation technology that lets the utility adjust and control each individual device from a central location.

Smart grids automatically monitor, protect, and optimize the operation of their interconnected elements from the central and distributed generators through the high-voltage transmission- and distribution networks, to industrial users and end-use consumers.

Smart grids enable bidirectional flows of energy and use two-way communication and control capabilities that lead to new capabilities such as connection of distributed renewable energy sources and better management of demand peaks. Further, smart grids promise improved efficiency that reduces total energy demand by limiting line losses and encouraging consumers to reduce consumption by flexible pricing and other tariff incentives. This improved efficiency and decreased consumption, together with greater use of efficient fossil fuel- and renewable-power sources, reduces the generation of carbon emissions and other pollutants.

Smart grids’ continuous monitoring allows automated systems or operators to detect and act upon dangerous situations or security breaches that threaten reliable and safe operation of the network. In addition, cyber security and privacy protection for customers is significantly enhanced. The built-in intelligence of smart grids allows rapid automatic intervention in the case of faults, limiting outage duration and lowering the utilities’ liabilities to penalties under “availability of service” agreements with the regulators.

intelligence of smart grids allows rapid automatic intervention in the case of faults, limiting outage duration and lowering the utilities’ liabilities to penalties under “availability of service” agreements with the regulators.