LAUSR

Abstract Multiterminal high-voltage direct current (MTDC) systems still need to be improved in terms of protection to maximize their availability. In this paper, a new distance protection algorithm is proposed. The fault distance is estimated using the frequency of the DC-side voltage oscillation and the cable travelling wave speed. The frequency is estimated using the Lomb-Scargle Periodogram (LSP). The LSP can calculate a signal spectral power for arbitrary frequency values. It can also process signals with missing samples, which makes it easier to use in real-world applications when data can be lost in the communication. In the proposed algorithm, only local measurements are used, without communication. The proposed algorithm was tested in a four-terminal MTDC system and was fully selective in simulation environment. To further verify the technique’s applicability, the proposed algorithm was embedded in a digital signal controller, and was simulated in real-time. In all the tests simulated in hardware, the faults were correctly detected and identified as being internal (zone 1) or external (zone 2). The results highlighted the potential of the Lomb-Scargle Periodogram and indicated that the proposed algorithm could be used in real-world applications, adding selectivity to multiterminal DC protection schemes.