System and Method for Monitoring Ultracapacitors

A system for monitoring operation of a bank of ultracapacitors configured to power an alternating current (AC) motor of a pitch system in a wind turbine, the ultracapacitors comprising a plurality of segments, the system comprising:

• a charging circuit;
• a resistive load;
• a current sensor configured to measure a discharge current of the ultracapacitors;
• and
• a control device having one or more processors configured to execute computer-readable instructions stored in one or more memory devices to perform operations, the operations comprising:
• coupling the ultracapacitors to the charging circuit to charge the ultracapacitors to a charging voltage;
• responsive to charging the ultracapacitors to the charging voltage, coupling the ultracapacitors to the resistive load to discharge the ultracapacitors through the resistive load;
• obtaining, via the current sensor, data indicative of a discharge current of the ultracapacitors during discharge through the load;
• determining a capacitance of the ultracapacitors based, at least in part, on the discharge current;
• and
• performing one or more control actions based, at least in part, on the capacitance.