A Method for Judging Harmonic Stability of HVDC Transmission System

Abstract

The invention relates to a method for judging harmonic stability of a high-voltage direct-current power transmission system. The method for judging the harmonic stability of the high-voltage direct-current power transmission system comprises the following steps of (1) obtaining an H matrix of a converter equivalent two-port network; (2) using a switch function to deduce an H matrix parameter expression; (3) using the H matrix to enable the high-voltage direct-current power transmission system connected with a converter to be equivalent to a simple RLC circuit, and obtaining a harmonic attenuation factor Re(Zcondc+Zdch), wherein, if the Re(Zcondc+Zdch) is smaller than or equal to zero, it is determined that harmonic waves are unstable, if the Re(Zcondc+Zdch) is equal to zero, it is determined that the high-voltage direct-current power transmission system is in a critical unstable state, and if the Re(Zcondc+Zdch) is larger than zero, it is determined that the high-voltage direct-current power transmission system is stable. According to the method for judging the harmonic stability of the high-voltage direct-current power transmission system, the conception is clear and the judgment method is easy and effective in the judgment process, the phenomenon that the high-voltage direct-current power transmission system is unstable can be effectively prevented from occurring by modifying related device parameters in the design stage of HVDC.

Description

technical field [0001] The invention belongs to the technical field of electric power engineering. In particular, it relates to a method for judging the harmonic stability of a high-voltage direct current transmission system. Background technique [0002] When there is a disturbance near the HVDC converter station, the phenomenon that the harmonic oscillation is not easy to attenuate or even amplify often occurs, which will pose a great threat to components such as the converter transformer, capacitor and reactor connected in series, and the distortion of the voltage will cause This will lead to difficulties in the operation of the DC transmission system or even system lock-up. [0003] The traditional method obtains the frequency impedance characteristics of the AC side of the converter through frequency scanning and other simulation methods on the AC and DC system, studies the influence of different short-circuit ratios on harmonic instability, or obtains the harmonic rel...

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Problems solved by technology

[0002] When there is a disturbance near the HVDC converter station, the phenomenon that the harmonic oscillation is not easy to attenuate or even amplify often occurs, which will pose a great threat to components such as the converter transformer, capacitor and reactor connected in series, and the distortion of the voltage will cause Causes difficulty in running the DC transmission system or even system lock-up

[0003] The traditional method obtains the frequency impedance characteristics of the AC side of the converter through frequency scanning and other simulation methods on the AC and DC system, studies the influence of different short-circuit ratios on harmonic instability, or obtains the harmonic relationship of the AC and DC side through simulation methods Matrix, the measurement method is cumbersome, and when the trigger angle, commutation angle, and transformer leakage reactance change, the matrix parameters also change, and need to be re-measured

None of these methods revealed the essential causes of harmonic amplification in HVDC transmission systems, nor did they provide a basis for avoiding harmonic instability

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