DC busbar protection for HVDC substations incorporating power restoration control based on dyadic sub-band tree structures

In this paper, a new direct current (dc) busbar protection for high voltage dc (HVdc) substations is proposed. The proposed scheme relies on the instantaneous current measurements obtained from the elements (lines and converters) connected to a dc busbar. Such current measurements are analyzed through dyadic sub-band tree structures that are used to extract the specific features, such as polarity, wavelet energy, and wavelet energy ratios. The performance of the scheme is assessed through the transient simulation using the verified PSCAD models. The simulation results revealed that the scheme can: 1) discriminate, effectively and within a very short period of time, between the internal and external faults; 2) detect pole-to-pole and pole-to-ground faults (both solid and highly resistive); 3) switch to healthy busbars (if available) to allow continuous operation; 4) re-energize the converter and restore the power to pre-fault conditions; and 5) remain stable during disturbances and external faults.