Boost Wind Turbine Availability and Reduce O&M Costs with Ultracapacitors for Emergency Pitch Control Backup Systems

A white paper by Maxwell Technologies


If a wind turbine is not spinning, it is not generating revenue.

Wind farm operators make every effort to maximize uptime, but a variety of factors contribute to turbines being offline. One challenging area can be the turbine’s battery-based emergency pitch control backup system.

Site managers often spend additional budget dollars and perform unscheduled maintenance to address the many performance issues associated with battery-based systems, including degraded performance in cold and hot weather conditions, battery voltage faults, and additional weekly or monthly turbine climbs to replace failed battery systems.

How can site managers eliminate costly and time-consuming maintenance of the pitch system’s backup power system? Fortunately, alternative robust energy storage technologies are available to help overcome the common pain points with battery-based systems.

Ultracapacitor energy storage is a well-established technology used as backup power for emergency pitch systems in turbines worldwide, both onshore and offshore. Ultracapacitors, also called supercapacitors or electric double layer capacitors (EDLCs), are high-power energy storage devices that store charge electrostatically with minimal chemical reactions which commonly occur in lead-acid batteries. As a result, ultracapacitor technology provides site managers with a significantly more reliable emergency pitch control energy storage solution that requires minimal maintenance and contributes to greater turbine uptime.

This white paper will examine the technical and business advantages of ultracapacitor-based energy storage for emergency wind pitch control systems.

The challenges of battery-based emergency pitch backup systems

The energy storage for emergency pitch control provides the energy necessary to pitch the wind turbine’s blades to a safe position during an emergency situation, such as loss of utility power or critical pitch system faults. The emergency pitch function is integral for preventing severe damage to or total loss of the wind turbine in the event of a dangerous condition. In GE 1.5 MW turbines, the emergency pitch systems are tested at least once per month to ensure the systems are prepared to react in the event of such emergencies.

Wind farms dealing with battery-based backup systems face three primary challenges: (1) battery faults; (2) premature battery system failures; (3) inventory, storage and waste management.