Sökning: "AC DC"

Visar resultat 1 - 5 av 152 avhandlingar innehållade orden AC DC.

  1. 1. Enhanced Active Resonant DC Circuit Breakers for HVDC Grids

    Författare :Tim Augustin; Hans-Peter Nee; Marley Becerra; Jürgen Biela; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Active damping; Actuator; DC circuit breakers; DC grid; DC power systems; Fast mechanical switch; Fault handling strategy; Gas discharge devices; HVDC; HVDC circuit breakers; Multilevel converters; Multiterminal HVDC; Power transmission; Spark gaps; Thomson-coil actuator; Vacuum interrupter; Voltage Source Converter VSC ; Electrical Engineering; Elektro- och systemteknik;

    Sammanfattning : High-voltage DC (HVDC) grids are considered promising for the electricity grid expansion required to integrate renewable energy sources into the existing infrastructure. DC fault currents increase rapidly and lack a current zero crossing. LÄS MER

  3. 2. Design and control of a DC collection grid for a wind farm

    Författare :Lena Max; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; DC collection grid; fault handling; DC DC converter; wind energy; control design; loss evaluation;

    Sammanfattning : In this thesis, the internal DC collection grid for a wind farm is investigated regarding the design, losses and dynamic operation for both normal operating conditions and for different fault conditions. The main advantage for the DC collection grid is the considerably lower weight of the 1 kHz transformers in the DC/DC converters compared to the equivalent 50 Hz transformers. LÄS MER

  4. 3. On the Analysis of DC Network Dynamics of VSC-based HVDC Systems

    Författare :Gustavo Pinares; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Frequency Domain Analysis; VSC Admittance; Eigenvalue Analysis; DC Grid Impendance; DC Grid Resonance; VSC; HVDC; DC Side Dynamics;

    Sammanfattning : In this thesis, the dc network dynamics of VSC-HVDC systems is investigated through eigenvalue and frequency domain analysis. The eigenvalue analysis has been used to identify the factors that have an impact on the system stability. LÄS MER

  5. 4. On Stability Enhancement in AC/DC Power Systems through Multi-terminal HVDC Controllers

    Författare :Omar Kotb; Mehrdad Ghandari; Oriol Gomis Bellmunt; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; AC DC power system; hybrid MTDC; multi-terminal HVDC; small signal stability; VSC-MTDC; Electrical Engineering; Elektro- och systemteknik;

    Sammanfattning : Due to the increasing share of renewable energy sources in modern power systems and electricity market deregulation, heavy inter-regional and cross-border power flows are becoming a commonplace in system operation. Moreover, large-scale integration of renewable energy sources is expected to pace up, therefore new solutions have to be developed to integrate these intermittent sources, which are also characterized by being distributed over large geographical areas, such as offshore wind farms. LÄS MER

  7. 5. Coordinated Frequency Control Between Interconnected AC/DC Systems

    Författare :Danilo Obradovic; Mehrdad Ghandari; Robert Eriksson; Jonas Persson; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Power System Dynamics; Frequency Stability; Small Signal Stability; HVDC Supplementary Power Control; Electrical Engineering; Elektro- och systemteknik;

    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