A Fast Current Protection Method for Thyristor Current Source Type Converter Circuit

Abstract

The invention discloses a fast current protection method of a thyristor current source type convertor circuit. The three-phase alternating current collection is performed through a three-phase currenttransformer arranged at each alternating current side of the thyristor current source type convertor circuit; zero drifting processing is performed; then, software convertor is used for converting the three-phase alternating current with frequency features into direct current with direct current pulse features only; finally fast current protection logic judgment such as overcurrent protection, differential protection and current change rate protection is performed on the basis of the direct current. The alternating current alternating along with the frequency is converted into the direct current by the invention; the protection logic judgment is performed on the basis; the sensitivity and fast moving performance of a topological circuit current protection algorithm are greatly improved; the frequency application range of the converted direct current protection method is wide; the action requirements of the current protection in a range of 2 to 120 Hz can be met; when the frequencies at the two sides of the convertor circuit are inconsistent, the method can overcome the defect of the alternating current protection method; the influence of the inconsistency of the frequencies is avoided.

Description

technical field [0001] The invention relates to the field of thyristor current source type converter circuits in power systems, in particular to a fast current protection method for thyristor current source type converter circuits. Background technique [0002] Because the large-scale condenser has a strong voltage stability and dynamic reactive power support function in the UHV AC-DC hybrid power grid, pumped storage and gas turbine units have a strong role in peak shaving and valley filling, emergency backup, and new energy consumption in the power grid. High-voltage direct current transmission can effectively alleviate the problem of reverse distribution of energy resources and power load in my country, and has great advantages in long-distance large-capacity power transmission. Therefore, large-scale condensers, pumped storage units, gas turbine units, and high-voltage direct current transmission etc. will continue to develop rapidly and healthily in the power grid. Thyri...

AI Technical Summary

Problems solved by technology

[0003] The current of the thyristor current source type conversion circuit is a square-wave waveform with positive and negative half-wave conduction at 120°, which has a large harmonic content and a wide range of frequency changes during frequency conversion operation. For example, fast protection algorithms such as AC Fourier and full-wave integration are used for protection. Amplitude calculation has disadvantages such as poor accuracy of amplitude affected by harmonics and long calculation cycle at low frequencies, which makes it difficult to meet the sensitivity and quickness requirements of protection logic judgment

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