Developments with the 60kW Westwind Wind Generator at Breamlea,Victoria by Michael Gunter, Breamlea Operations Group, ATA (paper submitted to the Wind Energy Workshop 1995 at Monash University) Purchase: This machine was sold at tender by Generation Victoria in September 1994. Its former owners were the State Electricity Commission of Victoria (now split up) and the Victorian Solar Energy Council (now Energy Victoria). The successful tenderer was the AlternativeTechnology Association Inc. at a bid of $18,000. Partial funding of the bid was from the former Brunswick Electricity Supply now part of CitiPower Ltd. CitiPower is purchasing the exported energy. Re-commissioning: A dedicated group of ATA members working voluntarily re-ommissioned it by early December 1994. This work involved complete renewal of all the mounting bolts of the slewing gearbox (some of which were sheared off), investigation of bronze filings in the slewing gearbox,tightening of loose nuts on the Aerostar blade tip-spoilers, electrical checks of the generator, power & signal wiring, and testing of critical microprocessor control functions. Our working hypothesis on the mechanical damage is that gusting crosswinds were, by a combination of lift and drag on the stationary airfoils, causing severe shockloading on the slew gearbox, thus driving the worm wheel "in reverse" and with the development of some backlash, eventually shearing off the mounting bolts (which may have worked loose after regular SECV maintenance ceased). It would appear that slewing mechanisms such as this are prone to damage unless the wind generator is kept continuously on-line, or at least kept pointing into the wind when stopped. Unreliability: Since re-commissioning we have been struggling to achieve both reliable operation and respectable energy export levels: From early February 1995 we were off-line for TWO MONTHS trying to locate an intermittent fault, which was eventually traced (with the help of both PowerCor and itiPower staff) to a corroded and partly burnt-out LV fusible link 5 metres up the distribution company's power pole! Return to service on 7 April 1995 signalled the start of the traditional autumn doldrums on the Victorian coastline, and our production was commensurate with the low wind regime. Additionally the machine has been dogged by shutdowns due to "low volts" condition being detected by the microprocessor controller. As there is no auto-restart, we have been losing considerable production time until one of our local members was alerted and performed a manual restart. The local distribution company PowerCor has this month been investigating voltage dips with a chart recorder, and has also replaced two further suspect corroded fusible links in their installation. The voltage sensors in the microprocessor have undergone minor adjustment to reduce sensitivity to voltage dips, and with the winds now picking up we are cautiously optimistic that production will approach the expected 100,000 kWh annually. Despite all the problems over the past 8 months we have exported 42,664 kWh in what appears to date to have been a year of below-average windspeeds. Data Logging and Data Communication: A "DataTaker" DT50 data logger, donated by Data Electronics has been programmed with a schedule which measures every half-hour average, maximum and minimum windspeeds, exported energy, minutes on-line in both low speed 8 pole mode and high speed 6 pole mode and average generator shaft speed. Three weeks' data can be stored in the internal memory. We have written a script for the shareware comms program "TELIX" which every 4 days interrogates the data logger on COM1 and captures the data to a file on disk. The file is then compressed with PKZIP, then another TELIX script talking to a modem on COM2 rings us up in Melbourne and uploads the zipped file. We are achieving a 60% reduction in STD phone bills by sending compressed data, and the modem is configured with auto-answer disabled for unbeatable security. Four days' data, the equivalent of four A4 pages full of numbers is uploaded in about 30 seconds (the modem is only 2400 bps). Preliminary data analysis suggests that the anemometer needs to be overhauled and recalibrated, as energy export for a given windspeed is slightly better than was being achieved in the SECV's 1987/88 monitoring program. Prospects for Wind Power in the new electricity market: When the ATA bought the wind generator, we were kindly given a large amount of related documentation by the former SECV unit which ran the Breamlea project. Part of this information was computer discs containing all the data from the Victorian Wind Monitoring Study (1985-87). Historical data of system demand (for electricity) is now readily available from the Victorian Power Exchange. Additional weather data (wind and temperature at Melbourne Airport) was bought from the Bureau of Meteorology. Using relational databases to combine the three data sets, we have been attempting to define the relationship, if any, between wind, temperature and the usage of electricity by Victorian consumers. The rationale for all this number crunching is that if a significant "wind chill" factor operates in winter, and hot winds cause increased demand in summer due to air conditioning loads, then wind energy producers should sell their energy not at a flat rate, but based on some relationship to the half-hourly fluctuations in the market price for electricity. It may now be irrelevant to regard wind power as some sort of unreliable "base-load" power, and wind sites which demonstrate the best correlation of windspeed with peaks in system demand will be the first places where wind farms will be economically viable. It would appear that the original ten sites used in the Victorian Wind Monitoring Study may not have been sufficient. Caution is required in relation to the possible effect of climate change in both reducing average windspeed at these latitudes, and increasing the severity of storms. In addition to system demand data we now have market price data, so perhaps another wind monitoring study is required, specifically looking for sites with the best correlation between windspeed and electricity price. Twelve months' data would seem to be an absolute minimum for each site chosen. The following page (see workshop.gif) is a summary chart of the data analysis. It shows the variation in weekday daytime (9am,noon, 3pm & 6pm) system demand in Victoria, expressed in 1990-equivalent MWh, as a function of dry-bulb temperature at Melbourne Airport. The 50th centile and the average of the highest 25% of demand readings in each temp group are shown. Adjacent figures are the average windspeed at Melbourne Airport for the corresponding temperature and demand data subsets. Note that small increases in windspeed are highly significant due to the cubic relationship with energy availability. M Gunter 25/8/95