Flatness-based control strategy of a grid-connected PMSG offshore wind farm to participate in Primary Frequency Control

This paper proposes an effective control strategy to enhance the Primary Frequency Control (PFC) capability of an offshore wind farm connected to the grid. A new nonlinear control method based on differential flatness properties of systems is applied to control the wind turbines in where, the control system is done by planning the appropriate trajectories on components of the output variables vector of the system. The PFC is assured by use of the energy reserve margins of the Wind Turbine Generators (WTGs). By starting from an imposed droop by the Transmission System Operator (TSO), news trajectories for the output variables of the system are generated and applied to the system control. Consequently, it allows the offshore wind farm to provide relief for the grid during depressed frequency conditions. Advantages of the proposed control method are in the one part, the simplicity of the system control strategy and in the other part, control and smoothing power of the wind farm during the transient state.