Collaborative modulation method based on power grid multi-circuit direct current

The invention discloses a collaborative modulation method based on power grid multi-circuit direct current. The collaborative modulation method based on the power grid multi-circuit direct current comprises the steps of (1) a power value of real-time transmission of a direct current line of each circuit is obtained to obtain the power, capable of being modulated in a real-time mode, of the direct current, (2) the modulation mode adopted by additional control of the direct current is learned about, (3) whether a fault is a monopole locking fault or a multipole locking fault is judged when the fault occurs in the direct current line of some circuit, (4) direct current modulation is not started to be used by the direct current of any one of multiple circuits when the fault is determined to be the monopole locking fault, (5) the obtained modulation mode is started to be used by other poles, in normal operation, of the direct current when a double-pole locking fault occurs on a four-pole operation direct current line, and (6) active power modulation of the direct current is rapidly started to be used by other two paths of direct current when the situation that the double-pole locking fault occurs on some double-pole operation direct current line, or a three-pole or four-pole direct current locking fault occurs on the four-pole operation direct current line is determined, and the total direct current delivery power of the multi-circuit direct current is increased to the maximum extent. The collaborative modulation method based on the power grid multi-circuit direct current needs to be developed in advance through an off-line simulation strategy, the frequency of generator tripping of a safety stability device can be reduced, and the overall economic benefit of operation of a power grid can be improved.