Charging of an energy storage system of a wind turbine

A control system configured to control a charging of an energy storage system of a wind turbine, wherein the wind turbine comprises a power generation system for generating electrical power and a power delivery interface for delivering the generated electrical power to an external system that is external to the wind turbine, wherein the wind turbine is configured to output a maximum amount of power via the power delivery interface that corresponds to a power rating of the wind turbine, and wherein the power generation system is configured to generate at least a first amount of electrical power that corresponds to the power rating of the wind turbine at the power delivery interface and a second amount of electrical power in excess of the first amount, wherein the control system is configured to perform:

• obtaining a maximum power limit to which electrical power supplied to the external system via the power delivery interface is limited, wherein the maximum power limit corresponds to the power rating of the wind turbine;
• monitoring at least one of an amount of electrical power provided from the power generation system to the power delivery interface or an amount of power generatable by the power generation system;
• determining if a predefined condition is met, wherein determining that the predefined condition is met requires at least determining, based on the monitoring, that the amount of power generatable by the power generation system comprises at least the first amount and the second amount of electrical power;
• and
• if the predefined condition is met, operating a power system of the wind turbine in a charging mode wherein an amount of electrical power equal or less than the second amount is supplied from the power generation system to the energy storage system to charge the energy storage system.