Patent ID: 11959976
Assignee: SOUTH CHINA UNIVERSITY OF TECHNOLOGY
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC G  H  Y | IPC G  H

Claim 0:
1. A DC converter valve state detection method based on temporal features of converter terminal currents, comprising the following steps:
S1. defining a HVDC transmission converter valve model, comprising a valve VT1, a valve VT2, a valve VT3, a valve VT4, a valve VT5, and a valve VT6, wherein the valve VT1 and the valve VT4 are connected in series to form a first branch, the valve VT3 and the valve VT6 are connected in series to form a second branch, the valve VT5 and the valve VT2 are connected in series to form a third branch, and the first, second, and third branches are connected in parallel, and wherein a connecting point between the valve VT1 and the valve VT4 in the first branch is defined as an a-phase measuring point of three-phase AC currents, a connecting point between the valve VT3 and the valve VT6 in the second branch is defined as a b-phase measuring point of the three-phase AC currents, a connecting point between the valve VT5 and the valve VT2 in the third branch is defined as a c-phase measuring point of the three-phase AC currents, and three-phase AC currents ia, ib and ic on a converter valve-side of a DC transmission system are collected, where ia, ib and ic represent an a-phase, a b-phase, and a c-phase of the three-phase AC currents respectively;
S2. defining a current when the currents of two commutating valves are equal as a base value, greater than the base value as a valve conducting current, and less than the base value as a valve blocking current;
S3. defining sequence detection as follows: a valve current relative relationship is constructed by a ratio of the valve conducting current to the valve current base value, a duty cycle of the valve current relative relationship being greater than a threshold is defined as a valve conducting state, and the valve conducting state is integrated within one cycle to construct a valve conduction time interval; and
S4. according to the steps S2 and S3, comparing time intervals of valve conducting states of the valve VT1, the valve VT2, the valve VT3, the valve VT4, the valve VT5, and the valve VT6 with a time interval of a valve conducting state in normal operation, and determining whether the valve state is normal and locating an abnormal valve according to a result of comparison.