2017-11-12 / Insight

The basics of turbine operations

BY ANDREW DIETDERICH
810-452-2609 • adietderich@mihomepaper.com

NORTH BRANCH TWP. — Many people likely only know that wind turbines have red flashing lights on top of them that create an interesting effect at night.

But there is a lot more to the massive industrial machines.

According to the U.S. Dept. of Energy, the easiest way to put it is that a wind turbine works opposite of a fan. Only as opposed to using electricity to make wind, like a fan does, wind turbines use wind to make electricity.

“Wind power is the ability to make electricity using the air flows that occur naturally in the earth’s atmosphere. Wind turbine blades capture kinetic energy from the wind and turn it into mechanical energy, spinning a generator that creates electricity,” according to the American Wind Energy Association.

At a minimum of 30 meters above the ground, according to the U.S. Dept. of Energy, wind turbines “can take advantage of faster and less turbulent wind.”

DTE Energy says on its website, “Michigan ranks among the top 15 states nationwide for potential for wind energy generation. The area around the Great Lakes is particularly well-suited for wind energy development because of the availability of higher wind speeds across flat land.”

The wind turbines being considered for northeast Lapeer County are well above the 30-meter mark.

Timothy W. Denney, Burnside Township attorney with Lapeer-based Rickard, Denney, Garno & Associates, said DTE has indicated the size of the wind turbines being considered for the area are 500 feet.

The maximum height is based on the highest point of a blade during rotation. Because blades typically are about 160 feet each, that means the center of the rotor where the blades connect is about 340 feet above the ground.

From afar, the top of a wind turbine behind the rotor can appear as a small box.

In reality however, the “small box” is more the size of a small room called a “nacelle” that is accessed via a straight-up climb via the pillar (tower).

Inside the nacelle, a lowspeed shaft connected to the wind-driven blades leads into a gear box. In the gear box, the low-speed shaft turning at 30 to 60 rotations per minute connects with a high-speed shaft that then turns at a rate of up to 1,800 rotations per minute — the kind of speed a generator (also in the nacelle) needs to produce electricity.

Researchers are constantly trying to improve wind turbine gear boxes to increase reliability, among other things. Such improvement include the possibility of using direct drive (gearless) wind turbines.

The nacelle also contains the controllers that collect and analyze wind info to automatically rotate the turbine to face the strongest wind and angle, or pitch, its blades to optimize the energy collected. And it’s all monitored via computer from afar.

Ultimately, the electricity (power) generated by a wind turbine is directed to a nearby substation via underground cabling, usually allowing farmers to continue using the rest of their land for agricultural-related purposes.

The substation then connects to the larger grid whereby power can be distributed to the end user.

The amount of power generated by wind turbines is measured in megawatts (MW) with 1 MW equal to one million watts. New wind developments usually are said to be capable of producing a certain level of electricity. DTE’s Pinnebog Wind Park in Huron County, for example, was commissioned in late 2016 and the company said the park’s 30 wind turbines have the ability to produce 50 MW “of clean, renewable energy — enough to power more than 22,000 homes.”

The U.S. Dept. of Energysupported Midwest Wind Energy Center says Michigan has “installed wind capacity” of 1,531 MW with “potential wind capacity” of 59,042 MW.

1. Blades: Lift and rotate when
wind is blown over them,
causing the rotor to spin. They
are comparable in design to an
airplane wing.
2. Rotor: Blades and hub together form the rotor.
3. Pitch system: Turns (or pitches) blades out of the wind to
control the rotor speed, and to
keep the rotor from turning in
winds that are too high or too
low to produce electricity.
4. Brake: Stops the rotor,
mechanically, electrically, or
hydraulically, as needed.
5. Gear box: Connects the lowspeed shaft to the high-speed
shaft, increasing the rotations
per minute (rpm) to generally
between 1,000 and 1,800 rpm
— the kind of rpm needed by
most generators to produce
electricity. When turbines fail,
it’s often this part that is the
source of the problems.
6. Generator.
7. Controller: Starts up the
machine at wind speeds
of about eight to 16 mph.
Likewise, shuts a turbine
down when wind speeds reach
about 55 mph to avoid being
damaged.
8. Anemometer: Measures the
wind speed and transmits
wind speed data to the controller. 9. Yaw drive: Orients turbine to
face the wind when direction
changes.
Source: U.S. Dept. of Energy

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