Method of retrofitting a wind turbine with an energy generating unit

A method of retrofitting a wind turbine having a tower and a first energy generating unit with a second energy generating unit, the tower having a total tower life at a first tower life expectancy design value, the first tower life expectancy design value being determined before the first period of time, the method comprising:

• removing the first energy generating unit from an upper end of the tower at an end of a first period of time, the tower having a remaining tower life less than the total tower life at the end of the first period of time;
• determining a second tower life expectancy value based on the remaining tower life and a generating unit life expectancy design value of the second energy generating unit at the end of the first period of time;
• coupling a tower transition adaptor to the upper end of the tower, the tower transition adaptor having a first end with a first interface sized for engaging with an interface on the upper end of the tower and a second end with a second interface sized for engaging with an interface on the second energy generating unit;
• coupling the second energy generating unit to the second end of the tower transition adaptor;
• determining a tower life of the tower used during the first period of time;
• determining the remaining tower life of the wind turbine tower;
• and
• operating the second energy generating unit to consume the remaining tower life at a lower rate than the first energy generating unit consumed the total tower life during the first period of time so as to extend the service life of the tower beyond the first tower life expectancy design value to the second tower life expectancy value,
• wherein operating the second energy generating unit further comprises operating the second energy generating unit at a rated power curve for the second energy generating unit.

A method of retrofitting a wind turbine having a tower and a first energy generating unit with a second energy generating unit, the tower having a total tower life at a first tower life expectancy design value, the method comprising:

• removing the first energy generating unit from an upper end of the tower at an end of the first period of time, the tower having a remaining tower life less than the total tower life at the end of the first period of time;
• coupling a tower transition adaptor to the upper end of the tower, the tower transition adaptor having a first end with a first interface sized for engaging with an interface on the upper end of the tower and a second end with a second interface sized for engaging with an interface on the second energy generating unit;
• coupling the second energy generating unit to the second end of the tower transition adaptor;
• determining a tower life of the tower used during the first period of time;
• determining the remaining tower life of the tower;
• and
• operating the second energy generating unit to consume the remaining tower life at a lower rate than the first energy generating unit consumed the total tower life during the first period of time so as to extend the service life of the tower beyond the first tower life expectancy design value to a second tower life expectancy value,
• wherein operating the second energy generating unit further comprises maintaining an effective tower life rate below a predetermined threshold, and
• wherein maintaining the effective tower life rate includes:
• measuring the loads acting on the tower over a period of time after replacing the first energy generating unit;
• determining the effective tower life rate based on the measured loads over the period of time;
• and
• reducing operating loads on the tower when the effective tower life rate determined is equal to or exceeds the predetermined threshold.