AUTHORS: Hussein. D. Al-Majali, Bilal. H. Al-Majali
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ABSTRACT: Control strategy for the modulation of the DC power for Modified HVDC Systems is proposed. A microprocessor- based firing scheme is presented which control the firing angles for modified HVDC converter with by-pass valves. Fast and continuous control of the DC voltage is possible with good operational characteristics. Using table-look-up algorithm to speed up the response, it gives a full range control of the firing angle for both rectifier and inverter modes. The algorithm is experimentally verified and is found to give a very-fast, precise and equidistant control of the thyristor triggering. Harmonic generations into the AC system and the converter reactive voltampere absorption have been reduced. The operations of modified bridge, the control algorithm and the microprocessor implementation are described. Experimental results on a laboratory model compare well with the predicted values.
KEYWORDS: HVDC Converter, Harmonics, Continuous Control, By-Pass-Valve, Microprocessor
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