Gearbox unit and wind power generation device

A gearbox unit for a wind power generation device, comprising

• a gearbox comprising an input element configured to be rotationally coupled with a main shaft of the wind power generation device and an output element rotationally coupled to the input element, wherein a rotational speed is increased from the input element to the output element;
• a lubricant supply system configured to supply lubricant to the gearbox for cooling and/or lubricating the gearbox, the lubricant supply system comprising an electric pump operable to discharge the lubricant;
• a primary power source;
• a backup power source;
• and
• a power controller configured to control supply of electrical power from the primary power source and/or the backup power source to the electric pump, whereby the electrical power is supplied from the backup power source in response to an available electrical power from the primary power source falling below a predetermined threshold that is less than a required electrical power of the electric pump.