A Calculation Method of Fault Current in Power System Containing Doubly-fed Wind Turbines

Abstract

The invention discloses a fault current calculation method for an electric power system considering excitation regulation characteristics of a double-feed wind power generator set. The method comprises the steps that S1, an equivalent controlled current source model of the double-feed wind power generator set under the influence of excitation regulation characteristics is built; S2, a positive sequence impedance matrix, a negative sequence impedance matrix and a zero sequence impedance matrix of the electric power system are built; S3, a fault point boundary condition equation in different fault types is built; S4, iterative calculation is carried out for obtaining the controlled current source value of the double-feed wind power generator set; S5, each sequence voltage value of each node during the current iterative calculation is obtained according to the controlled current source value of the double-feed wind power generator set, an electric network node voltage equation represented by the impedance matrix and the fault point boundary condition equation, and in addition, the practical voltage value of nodes is calculated; S6, the difference value between the practical voltage value of the node subjected to the current iterative calculation and the calculation value subjected to the iterative calculation in the former time is obtained, in addition, whether the difference value meets the preset error threshold limit value or not is judged, if so, the operation enters the step S7, if not, the correction value of the controlled current source is obtained, and the operation enters the step S5; S7, each sequence current of each branch is calculated, and in addition, the fault current value of each branch is calculated.

Description

technical field [0001] The invention belongs to the technical field of power systems, and more particularly, relates to a method for calculating fault current of a power system including the influence of excitation regulation characteristics of a doubly-fed wind turbine. Background technique [0002] Power system fault current calculation is the basic content of power grid operation control and relay protection setting calculation. In the traditional grid fault analysis method, it is assumed that the power sources in the grid are all synchronous generators. However, with the connection of wind turbines, the characteristics of the fault current fed into the grid have changed greatly, making it difficult for traditional fault analysis methods based on synchronous generator power to calculate the fault current value of the grid including wind turbines. [0003] At present, various research work has been carried out on the fault analysis method of wind turbines connected to the...

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Problems solved by technology

[0005] In view of the defects of the prior art, the purpose of the present invention is to provide a power system fault current calculation method that considers the influence of the excitation adjustment characteristics of the doubly-fed wind turbine, aiming to solve the short-circuit current of the power grid when the doubly-fed wind turbine is adjusted by the frequency converter. Problems that are difficult to calculate accurately provide technical support for the calculation of relay protection setting calculations for power grids containing doubly-fed wind turbines

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