Dillan Ockhuis

Dynamics of a Grid-Connected Small-Scale Geared Wind Turbine with Slip-Synchronous Technology D.K. Ockhuis Department of Electric and Electronic Engineering, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa. Thesis: M.Eng (Elec) March 2018 In this study, the dynamic behaviour of a 2.2 kW, fixed-speed downwind turbine is investigated. The downwind turbine drivetrain comprises of 1.9 m turbine blades, a gearbox with gear ratio of 1:3.78, a slip permanent magnet coupling and a permanent magnet synchronous generator (PMSG). The downwind turbine has a synchronous speed of 600 rpm (on the high-speed side of the gearbox) and is direct-grid connected by means of a grid connection controller (GCC). Each component of the downwind drivetrain was designed and developed by different persons however, the functionality of the drivetrain as a complete unit remains unknown. The 2.2 kW downwind drivetrain was modelled using mathematical equations which then translated to a simula...

The process of connecting small-scale wind turbine synchronous generators directly to the grid is not prevalent in literature. A wind turbine generator system not connected to the grid is a non-self-regulating system that has to be actively loaded and speed controlled prior to grid connection. In this paper, a grid connection power converter and a speed controller is proposed and developed for connecting a fixed-speed slip-synchronous permanent magnet generator (SS-PMG) to the grid. The power converter consists of a diode rectifier and Buck dc-dc converter with a resistive dump load, however, the diode rectifier and Buck converter are only active prior to grid connection, after which they are disconnected and the generator is directly connected to the grid. The proposed power converter is shown to provide acceptable and smooth grid connection performance as per the relevant grid codes. The proposed speed controller results in a single set of controller gains which are shown to be ca...

Wind power penetration into existing electrical power systems continues to experience year-on-year growth. Consequently, modern wind turbine systems (WTS) are required to comply with relevant grid codes and provide ancillary grid services to assist with overall grid stability. Adhering to these grid codes and services can cause additional mechanical loading on WTS, which can result in a reduction in service life of some of the drivetrain components, and instability if a sufficient means of damping is not present in the drivetrain. In this paper, a dynamic simulation model of a Type 1, direct grid-connected, fixed-speed (FS) slip-synchronous wind turbine system (SS-WTS) is developed to investigate its dynamic stability in response to the additional mechanical loads imparted onto it during transient events on the grid. The SS-WTS is not equipped with a power converter and, consequently, an understanding of its dynamic stability is critical to evaluate its ability to assist with grid s...