Modelling wind farm with synthetic inertia for power system dynamic studies

The requirement to increase system wind power penetration while providing better frequency quality has necessitated the wind turbines to emulate inertial response of the classical synchronous generators. This paper presents a simulation study done in order to understand the main factors that affect the potential for inertia emulation in a variable speed variable pitch wind turbine. A small power system consisting of three synchronous generators and one wind farm is modelled. Dynamic models are applied for all components in order to gain a more realistic understanding of the underlying phenomenon. The results show how the applied inertia emulation scheme influences the operation of the wind turbine. It is found that while the inertia time constant dominates inertia emulation in an under frequency event, the dynamics of the pitching system dominates inertia emulation in an over frequency event. The study provides an insight into how to design the inertia controller.