Sökning: "frequency stability"
Visar resultat 6 - 10 av 352 avhandlingar innehållade orden frequency stability.
6. Coordinated Frequency Control Between Interconnected AC/DC Systems
Sammanfattning : With ambitions of reducing the environmental pollution, power systems integrate larger shares of Renewable Energy Sources (RES) to phase out conventional thermal and nuclear generators. Since RES (such as wind and solar power) are connected to the grid through power electronics devices, they do not inherently contribute to system inertia. LÄS MER
7. Modeling of Modular Multilevel Converters for Stability Analysis
Sammanfattning : Modular multilevel converters (MMCs) have recently become the state-of-the-art solution for various grid-connected applications, such as high-voltage direct current (HVDC) systems and flexible alternating current transmission systems (FACTS). Modularity, scalability, low power losses, and low harmonic distortion are the outstanding properties that make MMCs a key technology for a sustainable future. LÄS MER
8. Dynamic Models of Wind Turbines
Sammanfattning : The impact of wind power generation in the power system is no longer negligible. Therefore, there is an urgent need for wind turbine models that are capable of accurately simulating the interaction between wind turbines or wind farms and the power system. LÄS MER
9. Wind Power - Added Value for Network Operation
Sammanfattning : This dissertation deals with the investigation on different value added properties of variable speed wind turbines (VSWT) that stem from the flexible controllability of converter interfaced wind turbines (WT). Improvements in voltage and transient stability of a nearby grid, small-signal stability improvement on the power system, frequency control support for the network operation, as well as thetechnical and the economic issues related to the reactive power ancillary service provision, are among the issues covered. LÄS MER
10. On bone quality and implant stability measurements
Sammanfattning : In conjuction with placement of oral implants, the jaw bone quality assessment is mainly based on quantitative radiographic measures and the subjective opinion of the performing surgeon. While the primary implant stability is discussed in terms of the pre-set motor torque and the subjective hand-felt perception during final tightening of implants, the secondary stability is defined as the absence of implant mobility. LÄS MER