Vol. 15, #680, 15 January 1996, published by the American Wind Energy Association

The full text of the WEEKLY is available
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It's official: 1995 warmest year on record


Wind integration not major problem for utilities Ontario Hydro awaits final bids on renewables RFP Wind-diesel workshop headed for Halifax in June


A preliminary assessment of weather data from around the world indicates, according to the British Meteorological Office and the University of East Anglia, that 1995 was the warmest year since recordkeeping began in 1856.

The earth's average surface temperature for the entire year was 58.72 degrees Fahrenheit, the groups said January 3, or 0.07 degrees warmer than 1990, the previous record-holder.

In addition, they said, the five-year period from 1991 through 1995 was the warmest on record, even though the earth was cooled for nearly two years by haze from the eruption of the Philippine volcano Mt. Pinatubo in 1991.

The new finding can be expected to lend additional credence to the theory that the earth is being warmed by human activities, in particular the emission of greenhouse gases from the burning of fossil fuels. An international panel of climate experts said in a recent report that scientific evidence to date "suggests a discernible human influence on climate."

Dr. James E. Hansen, director of the National Aeronautics and Space Administration's Goddard Institute for Space Studies in New York City, noted that the 1995 record was established despite the fact that two natural contributors to warming, solar energy and the El Nino current in the Pacific Ocean, were neutralized. Hansen, who said in 1988 that it appeared that the global climate had begun to change, told the NEW YORK TIMES that he expects at least "a couple more" recordbreaking years before the year 2000.

The British groups' finding is based on analysis of temperature readings from meteorological stations on land and at sea around the world. The Goddard Institute, which maintains a separate set of long-term data, also found 1995 to be the warmest year ever, but said the difference between it and 1990 was within the margin of sampling error and is therefore statistically insignificant.

A third set of measurements, the Spencer-Christy series of satellite readings begun in 1982, showed 1995 to be only about average for the period from 1982 to 1991, according to Dr. John R. Christy of the University of Alabama. Christy noted, however, that the 1982-1991 period was a warm one in the first place, and said the rate of warming measured by satellites is beginning to move into the range expected to result from human-caused warming.

Although the satellite measurements are considered to be more accurate than other data, they measure temperature only in the lower atmosphere, rather than at the earth's surface.


Integration of wind power plants into utility operating systems "has not been a problem," according to a new paper by Robert Putnam of the consulting firm Electrotek Concepts, "and any issues that have developed, such as intermittency and voltage regulation, can be addressed by accepted power system procedures and practices."

Putnam's paper, which has been submitted to the annual conference of the Institute of Electrical and Electronic Engineers (IEEE), was funded by the U.S. Department of Energy and is based on interviews with system operators and dispatchers from Pacific Gas & Electric Co. (PG&E) and Southern California Edison Co. (SCE). Both utilities have had extensive experience with the integration of wind energy on their systems since the early 1980s.

Putnam divides integration issues that have arisen with wind into "interface (or engineering) issues, operational issues, [and] planning issues." He describes how the interface and operational issues which were the focus of his investigation have been handled as follows:
Interface issues include harmonics, reactive power supply, voltage regulation, and frequency control.

Harmonics: "Harmonics are undesirable distortions of the utility AC sinusoidal voltage and current waveforms. . . . Harmonics are of concern due to potential damage to both utility distribution and customer load equipment. Some first-generation wind power plants installed in the early 1980s employed older, alternative conversion systems such as those using 6-pulse thyristor bridge configurations without external harmonic correction or filtering, resulting in the production of lower order harmonics . . . Advanced converter systems available today produce output with very little harmonic distortion, well below that specified in the IEEE Recommended Practice for Monitoring Power Quality. With the addition of harmonic correction devices and the current trend towards the use of advanced power electronics in variable-speed wind turbines, harmonics are no longer a significant utility concern."

Reactive Power Supply: "Early wind plants using induction generators were installed with inadequate hardware for reactive power compensation. As a result, utilities experienced increased line losses and difficulty controlling system voltage. . . . Wind plant operators were economically incented to improve the quality of power injected into the PG&E system when PG&E began to charge for excessive VAR [reactive power] support. SCE and PG&E now require small power producers using induction generators to provide near unity power factor at the point of interconnection. Power electronics technology used with modern, variable-speed wind turbines have demonstrated a full range of power factor control under all operating conditions, even with the wind turbine shut down."

Voltage Regulation: "Difficulty in controlling voltage regulation is accentuated when the wind plant is located in a remote area and connected to the utility through transmission lines originally designed to service only the load in the area. SCE experiences periodic voltage limitations on its 66 kV system in Tehachapi due to the weak system interconnection. Solutions considered by SCE include new transmission lines, alternative line arrangements, the addition of static or adaptive VAR controllers, and wind plant curtailment. Based on an economic analysis of each of these alternatives, SCE has determined that the least cost option is to curtail wind plant production and to compensate wind plant operators accordingly . . . "

Frequency Control: "Utilities operating wind power plants connected to weak, isolated grids can have difficulty maintaining normal system frequency. System frequency varies when gusting winds cause the power output of wind plants to change rapidly. While maintaining normal system frequency has not been a problem in the windfarm areas of California, it has been well documented on the Hawaii Electric Light Company (HELCO) system. [An] EPRI [Electric Power Research Institute] study showed that a reduction in capacity or an increase in demand of 10 MW per minute, caused by a combination of wind power output changes and/or unscheduled load changes, would cause HELCO's load-following generation plant, Hill 6, to trip, resulting in a loss of ability to regulate system frequency within acceptable limits. The report concludes that in order to accommodate more wind energy, the HELCO system would require

(1) the use of modern, variable-speed wind turbines with power electronic control and interface to the grid (the power electronic system can be controlled to limit wind turbine output during gusty or strong wind periods) and/or

(2) automatic generation control with additional spinning reserve.

In the case of SCE and PG&E, the short-term variations in wind plant output are small relative to normal load fluctuations and therefore to not significantly impact the ramping and cycling duties of available system regulating capacity."

Operational issues include operating reserve, unit commitment and economic dispatch, system stability, and transmission and distribution system impacts.

Operating Reserve: "Utilities carry operating reserve to assure adequate system performance and to guard against sudden loss of generation, off-system purchases, unexpected load fluctuations, and/or unexpected transmission line outages. Operating reserve is further defined to be spinning or non- spinning reserve. Typically, one-half of system operating reserves are spinning, so that a sudden loss of generation will not result in a loss of load, with the balance available to serve load within 10 minutes. Any probable load or generation variations that cannot be forecast have to be considered when determining the amount of operating reserve to carry. . . . At current wind plant penetration levels in California, the variability of wind plant output has not required any change in operating reserve requirements. The exact point at which the integration of intermittent generation such as wind begins to degrade system economics is unclear, but the technical literature suggests that it is at penetration levels in excess of five percent. Intermittency is becoming an increasing concern to utility operators in California, particularly during low demand periods, since wind plant penetration is beginning to reach this level. . . . As markets for electricity become more competitive, the ability to forecast and control the wind resource will increase the value of wind energy to utilities.

Unit Commitment and Economic Dispatch: Unit commitment is the scheduling of specific power plants on the utility system to meet expected demand. Units are committed to the schedule based on "generation maintenance schedules, generator startup and shutdown costs, minimum fuel burn requirements, and seasonal availability of intermittent resources such as hydro and wind. This schedule is usually made at least 24 hours in advance. . . . The most conservative approach to unit commitment and economic dispatch, and the one adopted by PG&E and SCE, is to discount any contribution from interconnected wind resources . . . In fact, wind plant output may be fairly predictable as in the case of the Altamont Pass region of California, due to seasonal and diurnal wind resource characteristics observed over many years of wind farm operation or as a result of wind resource monitoring programs. Further research is needed to develop the capability to accurately forecast wind plant output on an hourly basis over time periods ranging from one day ahead to one week . . . "

System Stability: " . . . Large wind turbines typically have low-speed, large-diameter blades coupled to an electric generator by a high-ratio gear box. This feature results in a large turbine inertia and low mechanical stiffness between turbine and generator [which] gives large wind turbines excellent transient stability properties. Operating experience with wind power plants in California confirms that wind turbine transients due to speed fluctuations or network disturbances have not resulted in system stability problems."

Transmission and Distribution System Impacts: Wind systems can affect transmission and distribution systems by "[altering] the design power flow or [causing] large voltage fluctuations . . . " Also, "islanding," in which a wind plant might energize a line that otherwise would be dead, has been a concern. "Operating experience with wind power plants in California has not shown system protection or safety to be an issue. Circumstances that may have led to islanding in the past have been identified, and hardware and detection schemes have been tested and approved. In PG&E's case, for example, the installation of direct transfer trip equipment is designed to trip the wind farms to prevent them from islanding."

Concludes Putnam, "The positive integration experience with wind energy in California . . . can provide valuable insights to utilities planning new projects and needs to become more widely understood."


Ontario Hydro has selected a short list of bidders from those replying to its 60-MW request for proposals (RFP) for renewable energy projects (see WIND ENERGY WEEKLY #661, August 28, 1995), and is awaiting final bids.

Bunli Yang, the Canadian utility's renewable energy strategist, said final bids are due by the end of this month on the 24 proposals on the short list. Thirty-six proposals were originally received.

There were three wind energy categories in the RFP, which asked for bids in six technology classes. The wind groupings included:

After the RFP was issued, the deadline for bids in the medium wind farm category was postponed for 42 weeks to allow developers time to conduct wind resource assessments.

In the individual category, bidders on the 11 shortlisted projects are: Fuller Electric, J. Weilandt, J. Liovas (2 proposals), Bidsmore, Controltech (3 proposals), Windtechnik, WenvorTechnologies, and Great Lakes Power. In the small wind farm category, four proposals, from Tacke Windpower, New World Power, Wolfe Island Power, and York Research, were shortlisted.

Ontario Hydro's plans for a Round 2 renewables RFP for 65 MW of capacity have been delayed, Yang said, due to a decision by the Ontario provincial government to charter a citizens' advisory group, the McDonald Advisory Committee, on competition in the electric power industry. The committee is scheduled to report on its findings in April. "The key issue [in Round 2] is how to encourage participation of our own business units," Yang said. "We are still having internal discussions on that, but I don't anticipate that we will be able to confer with stakeholders until well after the McDonald Committee finishes work."


Halifax, Nova Scotia, will be the site of the 10th International Wind-Diesel Workshop, sponsored by AWEA and the Canadian Wind Energy Association (CanWEA) and scheduled for June 11-12.

The workshop will be held at the Technical University of Nova Scotia and will include sessions on: technology review; remote community priorities, needs and requirements; diesel industry and plant operator requirements; financing, joint venture and implementation schemes; and penetration, storage, control and reliability issues, among others. Deadline for submission of papers or presentations is March 31.

The fee for the meeting will be Cdn $150. For further information, contact Malcolm Lodge, Island Technologies, Inc., PO Box 832, 49 Pownal Street, Charlottetown, PEI, C1A 7L9, phone (902) 368-7171, fax (902) 368-7139.



from the

Contact: Jessica Maier, (202) 383-2500

New Installations Expected to Total 18,500 MW by 2005

Worldwide installed wind power capacity surged to over 5,000 MW during the first quarter of 1996, and this strong growth in international wind energy markets is expected to continue, according to official projections released today by the American Wind Energy Association, which referred to wind power as "the world's fastest growing electric power technology."

Total installed wind power capacity will reach over 18,500 MW by 2005, according to the projections, representing a market of over $18 billion. Over 1,300 MW of new wind energy capacity was installed around the world in 1995 alone, a 35% percent increase in capacity over 1994. However, an imbalance in the world market exists: while many markets flourished in 1995, some slowed drastically--particularly the U.S.

Germany and India accounted for almost two-thirds of all new installations last year-- nearly 900 MW. The U.S., on the other hand, lagged behind, adding only 41 MW of new wind capacity. In the last ten years, the U.S. share of total world wind energy capacity has dropped from about 90 percent to 30 percent. "The rest of the world is forging ahead with wind energy development and leaving the U.S. in the dust," said AWEA's executive director Randall Swisher. "The current and future competitiveness of the U.S. in global energy markets is at risk."

Stagnation in the U.S. market can be attributed to the pending restructuring of the electric utility industry, which has made utility power planners gun-shy of planning any new capacity additions. The outlook for U.S. growth is hopeful, though, if the industry is restructured in a way that is friendly to renewables. AWEA's projections predict that U.S. wind capacity additions will grow slowly until about 2000, and then increase over the next several years, totalling about 2,700 MW of new capacity by 2005.

"Utility restructuring has caused a short-term mentality among many power planners, making them hesitant of any new capacity additions," said Swisher. "This short-sighted outlook could unfairly disadvantage renewables when the industry is restructured. If the U.S. wants to retain its leadership role in world energy markets, strong policy encouraging renewables must exist." Some of the policies AWEA proposes to ensure U.S. competitiveness are:

AWEA's projections are based on publicly and privately held information on existing installations and planned capacity additions worldwide. The projections assume no significant political shifts that would cause an increase or decrease in national support for wind energy. They also assume only a moderate shift in fossil fuel prices and efficiency gains from combustion technologies, as well as moderate improvements in the cost of wind-generated power.

Growth of Installed Wind Capacity in Selected Countries, 1995

Country          New capacity    Total installed       % growth,
               installed, 1995    capacity, 1995         1995

India                383 MW          565 MW               210%

Spain                 73 MW          145 MW               100

Germany              498 MW         1136 MW                77

Holland              106 MW          259 MW                69

United Kingdom        46 MW          193 MW                31

China                  7 MW           36 MW                23

Denmark               75 MW          614 MW                14

United States         41 MW         1770 MW                 2.4

TOP FIVE GROWTH MARKETS FOR WIND ENERGY Projected Additions Through 2005

        1996 1997 1998 1999 2000 2001 2002 2003 2004 2005    Total 

U.S.      30  150  200  150  200  300  300  400  500  500     2730 

India    400  300  300  250  250  200  200  200  200  200     2500 

China     50   50   50  100  150  150  150  200  200  200     1300 

Germany  300  200  100  100  100  100  100  100  100  100     1300 

Spain    100  125  150  150  200  150  100  100  100  100     1275 

AWEA, formed in 1974, is the national trade association of the U.S. wind energy industry. AWEA's membership of over 800 includes turbine and component manufacturers, project developers, utilities, academicians, and interested individuals from 49 states. Renewables Portfolio Standard A Detailed description is available from AWEA on the World Wide Web

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