Control and operation of wind power plants connected to dc grids
- Autores: Kevin Schönleber
- Directores de la Tesis: Oriol Gomis Bellmunt (dir. tes.), Sergio Rates Palau (codir. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2018
- Idioma: español
- Tribunal Calificador de la Tesis: Jon Are Wold Suul (presid.), Daniel Montesinos Miracle (secret.), Nicolaos Antonio Cutululis (voc.)
- Programa de doctorado: Programa de Doctorado en Ingeniería Eléctrica por la Universidad Politécnica de Catalunya
- Materias:
- Texto completo no disponible (Saber más ...)
- Resumen
Remote offshore wind power plants (WPPs) are being linked through high-voltage de voltage-source converter (VSC-HVdc) transmission to the main grids. The current deployments of HVdc grid connections for offshore WPPs are point-to-point transmission systems. Moreover, WPPs connected to the offshore VSC-HVdc form an offshore ac grid which operates non synchronously to the main grids. lt is characterized by extensive submarine cabling and, in the case offull-scale power converter-based wind turbines, by being purely converter-based.
This thesis goes into two main aspects regarding the operation of HVdc-connected WPPs: i) reactive power and voltage control and ii) fault ride through (FRT) in the ac offshore grids. Optimization-based reactive power control strategies are enhanced to the application of an ac grid consisting ofone grid-forming and several grid-connected converters. A reactive power and voltage control method is introduced which aims to increase the annual energy production from a single WPP. In the industrial application, several WPPs might be clustered which leads to multi-layered controllers and operation boundaries. Taking this into account, an operation strategy with reasonable communication requirements is suggested and evaluated against conventional methods .
The work further propases a control framework for the grid-form ing offshore VSC-HVdc. Special emphasis is put on the FRT of unbalanced faults in the offshore grid and the provision of controlled currents for ease of fault detection. Furthermore, the internal variables of the offshore modular multi-level VSC-HVdc are analyzed. Moreover, tour FRT strategies for the grid connected converters are evaluated for unbalanced faults in the offshore grid. This consequently implies that control strategies in symmetrical components are considered. Furthermore, the reduction of over-modulation and over-voltages by the power converters in the offshore grid is dealt with.
