July/August 2018

36 RENEWABLE ENERGY July/August 2018 www.drivesncontrols.com VSDs boost productivity by 65% at Greek pelletiser N izamis, a Greek manufacturer of wood pellets and briquettes used for domestic and commercial fuel, was encountering inconsistencies in the quality of its products due to its widespread use of manual production processes. It decided that it needed to automate to ensure consistency, while also reducing costs through improved quality and energy efficiencies. “The company’s workforce was manually handling production of the raw product which meant there was inconsistency in its quality,” recalls Theodore Amiridis of a local business, Automation Experts, that Nizamis brought in to help. “This often resulted in the product needing to go through the process again and again, increasing costs. They wanted to automate the system to ensure consistency while increasing efficiency and reducing energy costs.” The raw material used to make the pellets and briquettes can be anything from crop waste and wood shavings, to logs and tree branches. Processing these different materials involves a variety of equipment including heavy-duty wood cutters and clippers, sieves, grinders, pelletisers and air coolers. Many of these machines rely on heavy-duty motors which have to cope with varying demands. Amiridis recommended installing more than two dozen variable-speed drives to control the various motors. He suggested using the Optidrive P2 VSD from the Welsh drives-maker Invertek for heavy-duty processes such as the initial cutting, clipping and grinding stages. For other elements such as conveyors and lifts, he felt that Invertek’s Optidrive E3 would be more suitable. The drives were installed and connected via Modbus. “We installed and commissioned 25 drives and this immediately produced electrical savings of 50%, in addition to increasing productivity by 65%,” Amiridis reports. “The drives also ensured consistency throughout the process, with precise control over each and every motor. The company now has a complete and efficient automated production line.” A Greek producer of wooden pellets have halved its use of electricity and boosted its productivity by 65% by automation processes previously performed by hand. World’s largest pumped-storage hydro plant will use variable-speed technology When completed in 2021, the Fengning hydroelectric plant in China’s Hebei province will be the world’s largest pumped-storage power station, with an installed capacity of 3.6GW (in the form of a dozen 300MW pump-turbines housed in a huge underground cavern), and a predicted annual power generation of 3.4TWh. The aim is to complete the project in time to help stabilise the grid during the 2022 Winter Olympics when the demand for electricity to power nearby venues will be much higher than usual. Like other pumped-storage schemes, the $1.87bn Fengning plant will pump water from a lower reservoir to a higher reservoir during periods of low energy demand – such as overnight – when electricity is cheap. At times of peak demand, water will be released from the upper reservoir to return to the lower one via the pumps, now operating as hydroelectric generators. The Fengning hydro project is the first in China to use variable- speed technology. This will allow it to operate over a wide range of speeds that will help to optimise the performance of the pumping operation to the upper reservoir, as well as releasing water to the lower reservoir to generate power economically. The flexible system will improve efficiency and help to stabilise the regional grid. Construction work on the project began in 2013 with the Gezhouba Group as the main contractor. Under a €70m contract, which forms part of the project’s second phase, the Andritz group is supplying two variable-speed pump-generators, as well as AC excitation, governors, protection and control systems. The pump- generators will have a 345MVA capacity in the pumping mode, and 330MVA in the generating mode. GE’s Power Conversion business will provide the variable-speed technology, comprising two MV7000 variable-speed converters, for the two Andritz pump-generators, as well as a static frequency converter for four more pump-generators that are being supplied by Dongfang Electric Machinery. The Fenging project marks the entrance of GE’s variable-speed pump technology into the Chinese market.“We will bring more efficiency to hydro power production, which will help benefit the local community,”predicts Gagon Sood, CEO of GE’s Power Conversion’s industry, power and wind business.