A method to measure the strength index of interaction between converter stations of multi-infeed DC system

Abstract

The invention provides a method for measuring a strength index of interaction between converter stations of a multi-feed direct current system. The method comprises the following steps that (1)a multi-feed alternating current and direct current power grid receiving end system is taken as a research focus, direct current converter stations to be researched are determined, and it is assumed that the number of the direct current converter stations to be researched is N, and the direct current converter stations to be researched have three phases of A, B and C; (2) electromechanical transient simulation calculation is conducted on the power grid with electromechanical transient simulation software, a single-phase grounded short circuit with certain resistance is arranged at the phase A at a converter bus i, i=1, 2, ...N, the change of the voltage of the phase A at the converter bus i is observed, the grounded resistance of the short circuit is adjusted constantly, the voltage of the phase A at the converter bus i drops by 1% after the short circuit, the variation delta UAj of the voltage of the phase A at the converter bus j is recorded, j=1, 2, ..., i-1, i+1, ...N, and the calculation of the phase B and the calculation of the phase C are identical with that of the phase A; (3) a single-phase multi-feed interaction factor SMIIFij between the converter station i and the converter station j is calculated. By means of the method, references are provided for evaluating the strength of the interaction between all converter stations in the multi-feed direct current system in asymmetrical faults.

Description

technical field [0001] The present invention proposes a method for measuring the interaction strength index between converter stations in a multi-infeed DC system, especially a method for measuring the interaction strength between converter stations under asymmetric faults in a multi-infeed DC power transmission system The index SMIIF and its calculation method belong to the technical field of power system analysis. Background technique [0002] Multi-infeed DC transmission system means that multiple DCs are centrally connected to the same AC grid. With the continuous development of the power system, new features such as AC-DC parallel operation and multi-circuit DC centralized feed-in have appeared in the power grid. The multi-circuit DC systems are closely connected and interact with each other, and the stability characteristics are complex. Using quantitative indicators can clearly indicate the closeness of the connection between each circuit of DC systems. [0003] The ...

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Problems solved by technology

The multi-infeed interaction factor MIIF proposed by the CIGRE WG B4 working group can conveniently indicate the strength of the interaction between the DC circuits, but this index is based on the three-phase voltage symmetry. In the actual power grid operation, more often Asymmetrical faults, such as single-phase faults, in this case, the three-phase voltage of the system is asymmetrical. At this time, the use of indicators based on three-phase symmetry cannot accurately characterize the relationship between the asymmetrical faults. The strength of the effect

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