Page 50 - North American Clean Energy July/August 2019 Issue

wind power
Converter Component Failures
What you don’t know can hurt your bottom line
by Tommy Duckworth and Colleen Voisin
IRSP Partner
e key to improving wind turbine reliability
is bridging the gap between the wind farm and
the OEM. How do you do this? Partner with an Independent Repair Service Provider (IRSP). Wind farm managers should establish preventative maintenance strategies and preventative repair actions after the OEM’s warranty has expired. e IRSP can help reduce operation and maintenance costs by identifying high failure components which, in turn, will help extend overall turbine life. If
your IRSP isn’t experienced in servicing electronic components such as IGBTs, Pitch Controls, Printed Circuit Boards, PLCs, and can't fully load-test your AC drives/Converters, you should look elsewhere.
Another advantage of a great IRSP is the service warranty that they can provide to your equipment on the back end - anywhere from 3 months to 2 years. Equipment warranties vary from provider to provider, so dig in and really get to know what’s covered and what isn’t.
The Power Converter Blues
One failure unit that comes to an IRSP from
a wind farm is inarguably the Converter. The best way to identify high failure components is to open the unit and inspect the electronics. Not all Converters are created the same - high failure components will vary with each OEM. Take this failure example:
• IGBTs
• Flat ribbon cable that connect IGBTs to the
control board
• Clamp Capacitors
• Gate driver boards that mount to the IGBTs If there is an IGBT failure, the reasons could be
excessive voltages, excessive current or excessive thermal stress, or even insu cient cooling. Excessive currents can happen because of wrong
limits set forth for currents, or even an external short circuit (i.e.: motor, cable). Other failure factors could be temperatures, vibrations, humidity, and even age of components. All of these factors should be considered in order to accurately diagnose any performance issues and repair actions.
Troubleshooting Converters
Here is an e ective, 5-step process for troubleshooting and repairing Converters by an IRSP technician:
1. Remove the cover on the unit and perform a VOI (visual overall inspection); inspecting for any burnt, blown, loose connections, and bus caps that have swelled.
2. Perform a static check with a digital multi-meter (DMM). e DMM checks the inputs and outputs of the recti er section and the inverter section.
3. Power up the control board and power supply board to verify all voltages are correct.
4. Test the DC link for leakage, also known as Internal Resistance (IR).
5. Test the blower.
MAKE NO MISTAKE, THE WIND ENERGY
industry has experienced a serious boom. In 2018, wind energy generated 6.5 percent of the nation’s electricity. To
put that into perspective, it’s enough energy to power 26 million homes. Over the last decade, the US wind industry has invested over $142 billion in new wind projects - it is the largest source of renewable generating capacity in the country.
Despite growth of this industry, new wind turbines are expensive: up to $4 million per unit installed, which can last up to 20 years. Many things factor into the overall reliability and performance of each unit, including wear-out related failures, temperatures, humidity, precipitation, as well as
the age of turbine components. Older wind turbines will feed more into your operation and maintenance costs. Understanding and nding ways to improve the reliability and performance of these turbines is paramount. e cost of new equipment (from the OEM) isn’t cheap, nor is upgrading obsolete technology. Ordering replacement parts from your OEM often keeps a unit down for weeks because the parts are coming from overseas.
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