A Fast and Setting-Less Breaker Failure Backup Protection Scheme for Multi-Terminal HVDC Grids

Breaker failure backup protection schemes are essential for the reliable operation of high voltage direct current (HVDC) grids and to prevent damages to power system equipment due to sustained faults. This paper proposes a rapid, reliable, and setting-less breaker failure backup protection scheme for multi-terminal HVDC grids. The proposed scheme employs Hilbert-Huang Transform (HHT) to extract two features from local voltage measurements, namely the instantaneous frequency and energy. Based on detected outliers in the extracted instantaneous features, breaker failure events are rapidly detected. The proposed setting-less outlier-based criterion can be applied to HVDC grids with various configurations, parameters, and breaker technologies. The proposed scheme depends only on local voltage measurements to detect breaker failure events within $\text{1} \, \text{ms} $ from the intended breaker trip time without requiring breaker voltage or current measurements. In addition, the proposed scheme can successfully detect breaker failure events during high-resistance faults ($1500 \, \Omega$) and in grids with small boundary reactors ($\text{10} \, \text{mH} $). Numerous simulations in PSCAD/EMTDC software environment for a four-terminal HVDC grid are executed to demonstrate the rapid and reliable performance of the proposed breaker failure backup protection scheme under severe fault conditions.