Multi-terminal flexible DC power distribution network pilot comparison protection method and system

The invention belongs to the technical field of flexible direct-current power distribution networks, and provides a pilot comparison protection method and system for a multi-terminal flexible direct-current power distribution network. The pilot comparison protection method for the multi-terminal flexible direct-current power distribution network comprises two parts of protection starting and fault judgment. Starting protection: taking du/dt and di/dt as starting criteria; fault judgment: taking any one of the two ends of the protected line as a measurement point, and obtaining corresponding measurement voltage and measurement current; according to a known line parameter model, calculating a voltage integral value at the reference point as a reference voltage integral value; wherein the reference point is located outside the protected line; judging whether the fault point is located between the measuring point and the reference point or not according to the positive and negative characteristics of the referenc