The invention discloses a
harmonic instability determination method for a light-weight high-
voltage direct-current
power transmission 12-
pulse wave converter. The
harmonic instability determination method comprises the following steps of obtaining a relation of modulation from a
direct current side current to an
alternating current side, and a relation of modulation from an
alternating current side
voltage to the
direct current side according to a 12-
pulse wave converter switching function modulation theory; for low-order
harmonics, setting a
direct current side
fundamental frequency harmonic current to be Idcl(t) at a t moment; modulating the direct current side harmonic current to the
alternating current side through the converter as follows: a formula which is as shown in the specification; in a (t+<
delta>t) moment, obtaining harmonic
voltage change as follows: a formula which is as shown in the specification; obtaining harmonic
instability engineering criterion of a single-circuit direct current line according to current ratio at the (t+<
delta>t) moment and the t moment as follows: a formula which is as shown in the specification; and when a formula which is as shown in the specification is workable, showing that the current in the direct current side
system is increased constantly, the
system is instable, and the harmonic instability is excited. According to the harmonic instability determination method, by combination with a direct current magnetic
bias effect of a
transformer, a direct current magnetic bias coefficient is introduced; negative sequence
impedance parameters at the alternating current side are omitted; the alternating current side positive sequence secondary impedance and the direct current side
fundamental frequency impedance are adopted to determine whether the harmonic instability occurs or not, so that the determination method is more accurate and reliable.