Ultra-low frequency oscillation suppression method and system for DC output power grid

Abstract

The invention discloses a direct-current send-out power-grid ultra-low frequency oscillation restraining method and a system thereof. The method comprises the following steps that low-pass filtering is performed on collected frequency signals; after oscillation generated by a power grid satisfies a preset ultra-low frequency oscillation criterion, according to a frequency deviation signal, a control signal is generated; and a direct current valve control system adjusts direct current output power according to the control signal and increases system positive damping so as to reach a purpose of restraining ultra-low frequency oscillation. In the invention, disadvantages generated in the condition that a direct current frequency limit controller (FLC) and power grid operation personnel modify a water turbine speed regulator parameter so as to restrain the ultra-low frequency oscillation are overcome.

Description

technical field [0001] The invention relates to the field of power system stability control, and relates to a method and system for suppressing ultra-low frequency oscillation of a direct current transmission power grid. Background technique [0002] Due to the fast controllability of DC, this characteristic can be used to suppress ultra-low frequency oscillation in the DC output grid. Taking the DC transmission grid with a relatively high proportion of hydropower as an example, the prominent negative damping effect of the hydro turbine can easily lead to ultra-low frequency oscillation (oscillation frequency less than 0.1Hz) in the system under certain faults (short circuit fault, DC power boost, etc.). It is difficult to identify the oscillation source of the oscillation one by one, and the oscillation energy cannot be accurately calculated. [0003] Although the DC frequency limit controller (hereinafter referred to as FLC) has a certain inhibitory effect on ultra-low fr...

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Problems solved by technology

[0006] The present invention provides a method and system for suppressing ultra-low frequency oscillation of the DC output power grid, to at least solve the limitation that the existing power grid operators can only sacrifice the frequency modulation capability of the power grid by modifying the parameters of the turbine governor, and at the same time overcome the limitation when the ultra-low frequency oscillation amplitude is less than Insufficiency of FLC powerlessness after control dead zone of DC FLC

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