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Unreasonable control parameters of the Line Commutated Converter based High Voltage Direct Current (LCC-HVDC) system may induce small-signal instability. This paper studies the impact of inverter controller parameters on steady response of the LCC-HVDC system under weak AC grid condition. Firstly, according to a practical project, the small-signal model of LCC-HVDC system is established based on the switching function. Then, the eigen-analysis method is adopted to study the impact of the controller parameters on the inverter side on the oscillation mode and damping characteristics of the LCC system, and the correctness of results is verified by PSCAD/EMTDC simulation. The conclusion shows that reasonable controller parameters can improve the stability margin of the system.

This paper presents a detailed dynamic phasor modeling process of a line-commutated converter-based HVDC (LCC-HVDC) system. Firstly, the dynamic phasor models of the single-ended LCC rectifier station, inverter station and the DC line are established, respectively. Secondly, LCC-HVDC is an AC-DC-AC system. The interfaces are explained to connect the converter stations with the DC line. Through block modeling, it is helpful to simplify the process and verify the accuracy of each block. Finally, based on a practical project, the model is compared with the electromagnetic-transient (EMT) simulation results in PSCAD/EMTDC to verify the accuracy of the dynamic phasor model.