Converter synchronous stability control method and device based on real-time power grid impedance identification

Abstract

The invention relates to a converter synchronous stability control method and device based on real-time power grid impedance identification, and the method comprises the following steps: superposing a harmonic current with the frequency of fh on a current control link in a new energy station grid-connected system, and generating corresponding harmonic current and voltage at a PCC point through a power grid; measuring voltage and current data at a PCC point in real time, and analyzing and extracting a voltage component and a current component under the fh frequency by adopting an FFT function; calculating TE equivalent impedance based on the voltage component and the current component; on the basis of the PLL principle, according to the TE equivalent impedance, instruction values of active current and reactive current output by the converter are adjusted; the actual output current of the converter tracks the instruction value, so that after the output active current and reactive current reach the instruction value, the virtual power angle of the converter tends to be stable, and the frequency is consistent with the fundamental frequency of the power grid. According to the method, the impedance identification problem of the novel power system is solved, and the synchronization stability of the power system is improved.

Description

technical field [0001] The invention relates to a converter synchronous stability control method and device based on real-time grid impedance identification, belonging to the technical field of grid fault monitoring and diagnosis. Background technique [0002] Due to the continuous improvement of power electronics in the power system, the grid structure of the power grid is getting weaker and weaker, and the anti-interference ability is getting worse. Therefore, when the power grid fails, new energy sources need to maintain synchronous and stable operation with the power grid, that is, the frequency of the phase-locked loop (PLL) must be consistent with the fundamental frequency of the power grid to avoid large-scale power outages caused by the collapse of the power grid. [0003] Thevenin Equivalent (TE) impedance depends on power system topology and parameters. The new power system contains a large number of power electronic devices. For the problem of synchronous instabi...

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Problems solved by technology

The new power system contains a large number of power electronic devices. For the problem of synchronous instability with a small time scale, the traditional grid impedance identification method has low accuracy and does not consider the impact of the fault on the TE impedance. TE impedance information, thus limiting the application of adaptive current injection synchronous stability control methods in real power systems

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