This thesis investigates the effects of increased penetration levels of DFIG based wind turbines on rotor angle stability of power systems and how these impacts could be mitigated. The main outcome of this research is the comprehensive assessment of the stability improvements that can be achieved through a novel cost-effective control approach using existing DFIG equipments. A control strategy for both the rotor-side converter (RSC) and grid-side converter (GSC) of the DFIG is proposed to mitigate DFIGs impacts on the system stability. DFIG-GSC is utilised as a static synchronous compensator (STATCOM) to provide reactive power support during the active crowbar time when controlling of both reactive and active power is lost and a large amount of reactive power is absorbed. In addition, a supplementary power system stabiliser (PSS) is designed taking into account the influence of the crowbar system. To overcome the effects of PSS active power modulation, the PSS is designed to be implemented in the reactive power control loop of DFIG-RSC.The proposed approaches are examined on IEEE 9-bus and IEEE 39-bus systems under both small and large disturbances. The simulation results show the effectiveness and robustness of both approaches to enhance rotor angle stability. As the levels of wind penetration are increased, the benefit of such a control scheme is that the DFIG-based wind farms are able to take over the synchronous generators responsibility to support power system stability.As wind power is stochastic and fluctuates with the variation of wind speed, the proposed DFIG PSS should have the capability to damp power system oscillations effectively under non-uniform variable wind speeds across the wind farm. Therefore, the feasibility of the proposed fixed parameters PSS is evaluated using the IEEE 39-bus test system taking into account the non-uniform and variable wind speed profiles.The results confirm the robustness and stabilising effect against various operating modes and under various wind speeds.
|Date of Award||9 Jul 2017|
- University Of Strathclyde
|Supervisor||Kwok Lo (Supervisor) & Olimpo Anaya-Lara (Supervisor)|