Search for dissertations about: "dc networks"
Showing result 1 - 5 of 41 swedish dissertations containing the words dc networks.
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1. On the design of hybrid DC-breakers consisting of a mechanical switch and semiconductor devices
Abstract : The interest of using direct current in networks for both transmission and distribution of power is increasing due to the higher efficiency compared to the alternating current used today. As no natural zero crossings exist in direct current, the interruption of fault currents becomes a challenge. READ MORE
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2. The control of VSC-HVDC and its use for large industrial power systems
Abstract : With the recent developments in semiconductors and control equipment, Voltage Source Converter based High Voltage direct Current (VSC-HVDC) has become feasible. Due to the use of VSC technology and Pulse Width Modulation (PWM), it has a number of potential advantages: short circuit current reduction; rapid, independent control of the active and reactive power, etc. READ MORE
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3. Electromagnetic Modelling of Power Transformers for Study and Mitigation of Effects of GICs
Abstract : Geomagnetic disturbances that result from solar activities can affect technological systems such as power networks. They may cause DC currents in power networks and saturation of the core in power transformers that leads to destruction in the transformer performance. READ MORE
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4. Electromagnetic Modelling of Power Transformers with DC Magnetization
Abstract : DC currents that flow through the ground can be injected to the star windings of power transformers from their grounded neutral points and close their path with transmission lines. The geomagnetically induced currents (GICs) and AC/DC convertors of high voltage direct current (HVDC) systems are the sources of such DC currents. READ MORE
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5. On Stability Enhancement in AC/DC Power Systems through Multi-terminal HVDC Controllers
Abstract : 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. READ MORE