Method for damping oscillations in a line commutated converter high voltage direct current transmission system

Abstract

The application discloses an oscillation suppression method of a line commutated converter (LCC) high voltage direct current (HVDC) power transmission system, which comprises the following steps: firstly, a dynamic energy model of the LCC-HVDC is established by using a modular modeling method, wherein the dynamic energy model takes into account the control dynamics of a rectifier station, the operation characteristics of an inverter station and the electromagnetic characteristics of a DC line; then, the interactive energy among a constant current control loop at the rectifier side, a DC link energy flow and a frequency subsystem of a sending end power grid is analyzed by using an amplitude-phase analysis method; the key interactive energy item that induces instability of the DC sending system is accurately identified by extracting the non-periodic component of the energy; and on this basis, an additional energy compensation branch applied to the constant current controller at the rectifier side is designed, the system frequency feedback is introduced in real time, and the current reference instruction is corrected, so as to offset the interactive energy component that leads to instability, thereby realizing fast suppression of wideband oscillation of the system, and ensuring that the high-pass filtering link does not affect the steady-state power transmission balance point of the LCC-HVDC and the original control performance.

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