Calculation of valve damping circuit losses in 12-pulse HVDC convertors

An analytical method is presented for the calculation of valve damping circuit losses of a 12-pulse HVDC convertor, taking the effects of inductive coupling into account. The extra commutation notches introduced to the valve voltage waveform are expressed in terms of a notch factor, and a general equation for the valve damping circuit loss is derived. The equation is divided into two parts so that the effects of valve stray capacitance and multiple valve grading circuits can be accommodated in a logical manner. An additional component of loss arising from the thyristor stored change phenomenon is also discussed.<
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