A Brief on the Upgrade of Lead-Acid Batteries Used for Pitch Systems of Wind Turbines (Real essence)

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Wind turbines rely on backup power supply to feather the blades in case of a generator failure. In this case, battery modules have to provide sufficient voltage and current to start and move the generator for feathering, and ensure sound performance with multiplied power especially in harsh environment with low temperature.

 

The followings are statuses of some common energy storage units used for pitch control systems:

 

After careful tests and study, we believe that the causes of short lifetime of lead-acid batteries are as follows:

  1. Sulfation caused by undercharging or water loss caused by overcharging will exacerbate battery aging.
  2. Damaged external 24V UPS power supply results in management failure and deep discharge, which then cause falling off of active substance from the electrode plate, hence the diminishing capacitance.
  3. With no management system in lead-acid batteries, specific voltage and temperature of each module cannot be detected and the battery differential factors cannot be dealt with in time.
  4. Cycle life of batteries shrinks sharply if the ambient temperature is above 25℃.

 

Compared with lead-acid batteries, supercapacitors are more advanced and easy to use, though they have not been tested over time yet. There is still the concern that supercapacitors may fail to supply sufficient energy for feathering in extreme operating cases. Testing can be challenging given the equipment size and the complex testing process involving ESR, capacitance, and consistency. Regular manual operation for feathering and routine inspection on capacitance and ESR are helpful, but they cannot guarantee sufficient energy in supercapacitors either.

 

Lithium batteries are more cost effective compared with supercapacitors. New types of lithium batteries with longer lifetime are gaining great momentum, such as lithium iron phosphate battery and lithium titanate cell, thanks to the daily changing development in computer, communication, and consumer electronics, electric vehicles, and energy storage industry. The prospect stands that these new types of lithium batteries, once used as backup power for pitch control systems of wind turbines, require no maintenance at all in their 20-year-lifetime. No similar products in use can claim the same maintenance free feature for the time being.

 

 

A set of Micctech lithium battery module system consists of the management module and four 93.6V/5.2Ah battery modules in series.

 

 

Technical features and specifications of the management module are as follows:

 

 

Technical features and specifications of the battery module are as follows:

 

By the year 2017, Micctech has developed and delivered over 60,000 lithium modules and they are now supplying backup power for over 2000 wind turbines in the industry. The earliest ones were in use more than eight years ago. All of our products are now in stable performance and well recognized among clients. We did a site test on the modules put into use eight years ago at the beginning of this year, and found the capacitance of these earliest batch of products faded only by less than 20%.

Micctech is committed to offer reliable energy storage solutions to the wind power industry. For more information about our energy storage products, please leave us without your contact information on the web page or email us at sales@micctech.com. Technicians from our company will get in touch with you as soon as possible.