Construction method of quasi-steady-state model of direct-current system under asymmetric fault

Abstract

The invention discloses a construction method of a quasi-steady-state model of a direct-current system under an asymmetric fault. In a direct-current convertor station with extra-high voltage and extreme-high voltage, when an asymmetric fault happens on an alternating-current system, a control center in the station is used for obtaining the waveform information of triple-phase line voltage half cyclic wave of an inversion side alternating-current system, a zero-crossing moment of phase change line voltage is predicted through the practical waveform of asymmetric phase change voltage, a triggering moment of the trigger pulse of each thyristor valve block is improved so as to obtain the numerical values of direct-current average voltage and a phase change angle caused by the consideration of the change of the phase change voltage to obtain an improved quasi-steady-state model of the direct-current system under the asymmetric fault, and therefore, an alternating current / direct current hybrid power system can be quickly and accurately subjected to electromechanical transient simulation.

Description

technical field [0001] The invention belongs to the technical field of electromechanical transient simulation of AC and DC hybrid power systems, and in particular relates to a method for constructing a quasi-steady state model of an asymmetrical fault DC system. Background technique [0002] In recent years, EHV and UHV DC power grids have been put into operation in many areas of my country, which put forward higher requirements for the safe and stable operation and control of power grids. The total length and transmission capacity of the ultra-high voltage direct current transmission system that has been built and put into operation in China ranks first in the world. In the next 15 years, China's power grid will be an ultra-large-scale AC-DC hybrid grid with more than 20 ultra-high voltage and ultra-high voltage DC transmission lines. Due to the large-scale DC transmission system being put into operation, a large number of high-power power electronic devices and other nonl...

AI Technical Summary

Problems solved by technology

The two main defects of the classical quasi-steady-state model are: (1) The DC side voltage is calculated by using the formula for calculating the average value of the symmetrical commutation voltage, but in the actual simulation, the calculation method of the DC average voltage under the action of asymmetrical voltage has many problems. Large deviations, which affect the accuracy of calculations

(2) The calculation method for the cut-off front angle of the inverter side still adopts the calculation method in the case of symmetry, which does not take into account the factors of the movement of the zero-crossing point of the commutation voltage and the influence of the change of the commutation angle caused by the change of the commutation voltage

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