Page 16 - North American Clean Energy January February 2015

wind power

Scheduling More Wind Power

Exploiting probabilistic forecasts

By Dr Eric Grimit, Dr Jeffrey Lerner, Charles Maalouf & Francesca Davidson

Every day at wind plants across the United States, there’s an important daily task that’s approached as a matter of

routine. hat task is providing the required schedule of tomorrow’s expected wind output for the day-ahead electricity

market.

Typically, the professionals carrying out this task are risk adverse, and often use simple the tools and information required to extract additional value from this daily routine. he

rules of thumb to submit their day-ahead schedules. One such example is submitting only solution: a better understanding and exploitation of probabilistic forecasts, which would
half of the expected output to minimize the risk of getting caught short in the real-time allow more energy to be scheduled into the day-ahead market, without increasing the risk
market, with the view that everything will “settle out” in the real-time market.
of under-delivering any power.
However, experience suggests this is a major lost opportunity—potentially, by as much

as three gigawatt-hours (GWh) for an average-sized, 100-megawatt (MW) plant every Power marketing practices
month.
Scheduling and trading wind energy is by no means a simple task. he party responsible for
Although wind plant energy schedulers would likely agree there’s more money to be marketing energy from a wind plant has many factors to consider. Over-delivering usually
made with a risk-adjusted scheduling strategy for the day-ahead market, they often lack
leads to imbalance charges, which are imposed for forcing curtailment of other energy

sources. Sometimes this even means curtailment of the wind project itself. On the other
hand, under-delivering usually means paying for more balancing reserves, and often at
high, spot-market prices.
At the same time, those marketing wind power have to be cognizant of the wind

conditions around a project, which can cause transmission congestion either at the hub or
node level, leading to price spikes. Volatility in the real-time market can also occur when
the wind energy predicted across a region for the next day is either signiicantly exceeded

or fails to materialize.
Ramping down a wind power plant’s production, when more energy is available than
From the beginning, SGS Herguth was there! The wind industry was held anticipated, is generally manageable. But, it’s impossible to ramp up production to match
together by dedicated wind farm technicians and supported by SGS Herguth.
a project’s stated power delivery if there’s a lack of wind. his reality, along with the
SGS Herguth ensures early identiication of wear debris and contaminants:
asymmetry of penalties versus rewards, places most of the focus on downside risk, or the
• Wear Debris & Contamination Analysis for Oil and Grease
risk of being short of the energy promised to the grid in any given hour. he result is more
Plasma Spectroscopy on Acid Dissolved Metals
conservative scheduling practices.
Filter Debris Analysis
Direct Reading and Analytical Ferrography
To avoid penalties from under-delivering, those marketing power tend to gravitate
Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS)
toward a behavior known as “scaling” or “haircutting” the wind power forecast. In this
• Lubricant Life and Serviceability Evaluations for Oil and Grease
approach, the marketer scales down or gives a “haircut” to the forecast by a fraction,
Acidity and Viscosity
sometimes 50% or more.
Remaining Antioxidant Levels
When a period with many up and down ramps is anticipated, marketers may also
Flender Foam and Air Entrainment Tester ASTM Foam and Air Release Testing
Grease Evaluations
trend toward conservatism, only scheduling the minimum amount possible. Usually, this
minimum is what they have reserve capacity contracts for and no more. For example, if
Contact us today for all of your testing needs! the forecast shows a ramp down to 30 MW, and the owner has a reserve capacity contract
800-645-5227 (OIL-LABS) www.sgsherguth.com

16 JANUARY/FEBRUARY 2015
nacleanenergy.com