Abstract: A method of supplying power to an electrically isolated wind farm is provided including a plurality of wind turbines and a power generator. In a low wind condition, where a wind speed falls below a threshold value, active power and reactive power is supplied from the power generator to a first wind turbine and wind farm passive components. In a second operation mode after the first operation mode, active power is supplied from the power generator to the first wind turbine and a second wind turbine, and reactive power is supplied/consumed by the first wind turbine to the cables and transformers between it and the second wind turbine.

Abstract: A method of performing a black start in a wind farm is provided, the wind farm including a primary black start enabled wind turbine, at least one secondary black start enabled wind turbine, and a wind farm grid interconnecting at least a part of the wind turbines in the wind farm, the method including (a) starting the primary black start enabled wind turbine in black start mode in order to supply voltage to the wind farm grid, (b) monitoring, at the at least one secondary black start enabled wind turbine, an electric parameter value in the wind farm grid, and (c) starting the at least one secondary black start enabled wind turbine in black start mode in order to supply voltage to the wind farm grid when the monitored electric parameter value meets a predetermined condition. A corresponding wind farm is also provided.

Abstract: Provided is a method of controlling at least one converter of at least one wind turbine connectable to a wind park grid of a wind park during black start or island mode of the wind park, the method including: ramping up a converter voltage reference unless a power related condition and/or a wind park grid frequency related condition or a converter current related condition is violated.

Abstract: A method of supplying power to an electrically isolated wind farm is provided including a plurality of wind turbines and a power generator. In a low wind condition, where a wind speed falls below a threshold value, active power and reactive power is supplied from the power generator to a first wind turbine and wind farm passive components. In a second operation mode after the first operation mode, active power is supplied from the power generator to the first wind turbine and a second wind turbine, and reactive power is supplied/consumed by the first wind turbine to the cables and transformers between it and the second wind turbine.

Abstract: A method of performing a black start in a wind farm is provided, the wind farm including a primary black start enabled wind turbine, at least one secondary black start enabled wind turbine, and a wind farm grid interconnecting at least a part of the wind turbines in the wind farm, the method including (a) starting the primary black start enabled wind turbine in black start mode in order to supply voltage to the wind farm grid, (b) monitoring, at the at least one secondary black start enabled wind turbine, an electric parameter value in the wind farm grid, and (c) starting the at least one secondary black start enabled wind turbine in black start mode in order to supply voltage to the wind farm grid when the monitored electric parameter value meets a predetermined condition. A corresponding wind farm is also provided.

Abstract: A method of operating a wind turbine during disconnection from a utility grid includes a generator, a wind turbine converter, in particular including a grid side converter portion connectable to the utility grid, a DC link, a generator side converter portion, and a UPS, the method including: allowing the UPS to draw, according to an UPS active power reference, active power from the wind turbine converter (104); controlling the wind turbine converter by a converter power reference to meet the UPS active power reference. Controlling the wind turbine converter by the converter power reference includes modulating a frequency of the converter terminal voltage in dependence of the converter power operating point, in particular the converter power reference.

Abstract: A system for supplying electric power to a grid and for supporting the grid is provided. The system includes (a) a power generator including a main converter, (b) an energy buffer including an energy storage and a secondary converter, (c) a grid stability monitor-configured to provide a grid stability, and (d) a controller configured to control the main converter and the secondary converter in dependency on the grid stability indication such that when the stability level is at least equal to a predetermined threshold value, the main converter is controlled to operate as a virtual synchronous machine and the secondary converter is controlled to operate to maintain a predetermined amount of energy in the energy storage, and when the stability level is below the predetermined threshold value, the secondary converter is operated to provide a predetermined response in order to support the grid stability.

Abstract: Provided is a method of controlling an energy storage device arranged to provide frequency support for an AC power system, the method including: setting an amount of energy stored in the energy storage device depending on a power system frequency of the AC power in the AC power system.

Abstract: Provided is a method of controlling at least one converter of at least one wind turbine connectable to a wind park grid of a wind park during black start or island mode of the wind park, the method including: ramping up a converter voltage reference unless a power related condition and/or a wind park grid frequency related condition or a converter current related condition is violated.

Abstract: A converter network bridge controller for a power converter hardware being connectable to an alternating current electricity network is provided. The controller includes an output unit configured for generating a quadrature voltage component reference to a PWM modulator which determines the switching of the power converter hardware, wherein the quadrature voltage component reference includes a first signal and a second signal. The output unit includes a first part and a second part. The first part is configured for generating the first signal based on a current reference for an active current to be generated by the power converter hardware. The second part is configured for providing the second signal to reduce a difference between a converter active current component of measured feedback current and the current reference for active current.

Abstract: A system for supplying electric power to a grid and for supporting the grid is provided. The system includes (a) a power generator including a main converter, (b) an energy buffer including an energy storage and a secondary converter, (c) a grid stability monitor-configured to provide a grid stability, and (d) a controller configured to control the main converter and the secondary converter in dependency on the grid stability indication such that when the stability level is at least equal to a predetermined threshold value, the main converter is controlled to operate as a virtual synchronous machine and the secondary converter is controlled to operate to maintain a predetermined amount of energy in the energy storage, and when the stability level is below the predetermined threshold value, the secondary converter is operated to provide a predetermined response in order to support the grid stability.

Abstract: Provided is a method for starting a wind park including plural wind turbines connectable in a collector system connectable to a utility grid, the method including: starting at least one first wind turbine, each being equipped with an utility grid independent energy supply and a grid forming function, to produce electrical energy from wind energy, thereby utilizing the respective grid independent energy supply for starting; performing the grid forming function by the first wind turbine to achieve a reference voltage in the collector system; starting at least one second wind turbine and/or at least one third wind turbine to produce energy by conversion of wind energy, thereby utilizing energy provided in the collector system for starting.

Abstract: A converter network bridge controller for a power converter hardware being connectable to an alternating current electricity network is provided. The controller includes an output unit configured for generating a quadrature voltage component reference to a PWM modulator which determines the switching of the power converter hardware, wherein the quadrature voltage component reference includes a first signal and a second signal. The output unit includes a first part and a second part. The first part configured for generating the first signal based on a current reference for an active current to be generated by the power converter hardware. The second part is configured for providing the second signal to reduce a difference between a converter active current component of measured feedback current and the current reference for active current.

Abstract: Provided is a method for starting a wind park including plural wind turbines connectable in a collector system connectable to a utility grid, the method including: starting at least one first wind turbine, each being equipped with an utility grid independent energy supply and a grid forming function, to produce electrical energy from wind energy, thereby utilizing the respective grid independent energy supply for starting; performing the grid forming function by the first wind turbine to achieve a reference voltage in the collector system; starting at least one second wind turbine and/or at least one third wind turbine to produce energy by conversion of wind energy, thereby utilizing energy provided in the collector system for starting.