Hay River, Northwest Territories: The Northwest Territories Power Corp. (NTPC) announced commissioning February 16 of a 590kW Variable Speed Generator (VSG) Project in Aklavik.
Electricity is now being provided to the more than 300 NTPC customers in Aklavik using a converter-based VSG platform. The VSG will also integrate solar power from a new 55 kilowatt solar array, installed by the GNWT earlier this year. The new technology is projected to reduce diesel consumption by approximately 80,000 litres per year, which would result in a greenhouse gas emission reduction of 210 tonnes, through improved efficiency of diesel generation.
With the VSG platform now live, a one year trial period will commence to assess performance against expectations. At the end of the trial, NTPC will determine whether to broaden use of variable speed generators to other locations.
The Government of the Northwest Territories provided funding support for the project.
Australia’s Centre for Renewable Energy and Power Systems (CREPS) recently published an independent technology whitepaper on variable speed diesel technology that identifies VSG as a prime solution to the challenge of integrating renewables with diesel generator based off grid systems.
The CREPS paper states: “Variable speed diesel application will significantly reduce the cost of high penetrations of renewable energy into remote and off-grid power systems, without substantially changing the technology footprint. Accordingly diesel based technologies have a pivotal role in transitioning off-grid power systems to a reduced reliance on diesel fuel.”
The paper explains that conventional diesel generators run at a fixed speed, 1800 rotations per minute for 60Hz systems or 1500 rpm for 50Hz. Variable speed diesel generators can run at any rotational speed, as determined by which speed provides the greatest efficiency for any load setting. The generator is still able to meet the requisite system frequency, with a power converter placed between the generator and the load. The power converter ensures the variable frequency output of the generator is conditioned to meet the network frequency.
The approach is common across wind, solar PV and battery technologies, the paper says, which generate at either variable speed or are direct current technologies. Reliance on a power converter does not reduce the reliability of the approach. However it does improve the power quality and security that can be offered to support the network. The ability of the variable speed generator to select its preferred speed setting is responsible for performance improvements – the paper cites fuel savings for VSG as high as 60% when it’s deployed in partnership with renewables. For applications that are already benefiting from renewables and energy storage, addition of VSG can bring up to an additional 30% of fuel savings. The generator is no longer constrained to a very narrow speed reference (akin to driving your car without ever changing gear).
Mechanical gearbox concepts also exist to achieve variable speed operation, however these increase, rather than decrease the complexity and cost of the approach.
To download a copy of the CREPS Whitepaper, visit the Innovus Website, http://www.innovus-power.com/.