Qatar University

Other

Qatar Foundation for Education, Science and Community Development

Ahmed Elserougi

Ahmed Massoud

Shehab Ahmed

Ayman S Abdel-Khalik

Ahmed Salah Morsy

An electrical converter is provided, comprising a first half-bridge sub-module, a switch, and a first capacitor. The half-bridge sub-module is connected to the first capacitor, and the switch is connected to a terminal of the first half-bridge sub-module. The switch includes a plurality of insulated-gate bipolar transistors. The insulated-gate bipolar transistors are serially connected with each other.

Self-balanced non-isolated hybrid modular DC-DC converter based on low duty cycle operation and sequential capacitors charging/discharging for medium voltage DC grids

An electrical converter, comprising a plurality of first modules and a plurality of second modules. At least one of the plurality of first modules includes a half-bridge module coupled with a direct current (DC)-link capacitor. A diode connected across the DC-link capacitor and a thyristor. At least one of the plurality of second modules is connected to at least one of the plurality of first modules.

Modular isolated half-bridge based capacitor-tapped multi-module converter with inherent DC fault segregation capability

Voltage balancing and extracted output power circuit topologies use maximum power point and maximum power point tracking to provide voltage balancing and voltage and current adjustment to optimize extracted output power for corresponding DC voltage source strings (). The topologies used to control power generation include one or more voltage balancing circuits and/or power system optimizer circuits () to reduce decreased power utilization and enable independent operating voltages of DC voltage source strings () to provide voltage balancing and to deliver a maximum power independent of the voltage and current of other DC voltage source strings (). The current flowing in each DC voltage source string is controlled by the duty ratio of the corresponding switch (). The circuit topologies can include a plurality of voltage balancing/power system optimizer circuits ().

Apparatus and method for voltage balancing and optimizing output power in power generation systems

The method of converting high voltage AC lines into bipolar high voltage DC systems makes use of the three transmission lines (referred to as the positive pole, the negative pole, and the modulating pole) in an existing high voltage AC system as transmission lines in a bipolar high voltage DC system. When current from the power source is up to the thermal current limit of the transmission lines, the transmission lines operate in two-wire mode, where current is delivered in the positive pole and returned in the negative pole, the modulating pole being open. When power source current exceeds the thermal current limit, operation is in three-wire mode, alternating for predetermined periods between parallel configuration of the positive pole and the modulating pole to divide current for delivery to the load, and parallel configuration of the negative pole and the modulating pole, dividing the return current.

Three wire DC transmission circuit with modulated pole

The direct current (DC) side fault isolator for high voltage direct current (HVDC) converters () includes a first set of double thyristor switches () connected across the line-to-line voltage terminals between first and second phases of alternating current (AC) terminals of a HVDC converter (), and a second set of double thyristor switches () connected across the line-to-line voltage between the second phase and a third phase of the AC terminals of the HVDC converter (). In use, the first and second sets of double thyristor switches () separate the HVDC converter () from an external power grid () during direct current (DC) side faults by turning on these thyristors ().

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Doha, Qatar

Ahmed Elserougi