Resonance Investigation and Active Damping Method for VSC-HVDC Transmission Systems under Unbalanced Faults

Grid unbalanced faults can cause core saturation of power transformer and produce lower-order harmonics. These issues increase the electrical stress of power electronic devices and can cause a tripping of an entire HVDC system. In this paper, based on the positive-sequence and negative-sequence impedance model of a VSC-HVDC system as seen from the point of common connection (PCC), the resonance problem is analyzed and the factors determining the resonant frequency are obtained. Furthermore, to suppress over-voltage and over-current during resonance, a novel method using a virtual harmonic resistor is proposed. The virtual harmonic resistor emulates the role of a resistor connected in series with the commutating inductor without influencing the active and reactive power control. Simulation results in PSCAD/EMTDC show that the proposed control strategy can suppress resonant over-voltage and over-current. In addition, it can be seen that the proposed strategy improves the safety of the VSC-HVDC system under unbalanced faults.

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Cite this article

[IEEE Style]

X. Tang, R. Zhan, Y. Xi, X. Xu, "Resonance Investigation and Active Damping Method for VSC-HVDC Transmission Systems under Unbalanced Faults," Journal of Power Electronics, vol. 19, no. 6, pp. 1467-1476, 2019. DOI: 10.6113/JPE.2019.19.6.1467.

[ACM Style]

Xin Tang, Ruoshui Zhan, Yanhui Xi, and Xianyong Xu. 2019. Resonance Investigation and Active Damping Method for VSC-HVDC Transmission Systems under Unbalanced Faults. Journal of Power Electronics, 19, 6, (2019), 1467-1476. DOI: 10.6113/JPE.2019.19.6.1467.