HVDC commutation failure fault diagnosis method based on valve voltages or valve currents

Abstract

The invention discloses an HVDC commutation failure fault diagnosis method based on valve voltages or valve currents. The method comprises the following steps that a commutation failure mechanism and commutation failure influence factors are analyzed; commutation failure process analysis is carried out, and a commutation failure criterion is determined; an HVDC model contravariant side equivalent circuit is built, and a commutation failure critical inductance value is determined; whether the diagnosis result is accurate or not is verified through simulation. According to the fast commutation failure diagnosis method based on the converter valve voltages or the valve currents, the theoretical analysis and stimulation result proves the accuracy and effectiveness of the method, no blind diagnosis area exists, and the method is simple in theory and easy to implement, and has certain project application value.

Description

technical field [0001] The invention relates to a fault diagnosis method for HVDC commutation failure based on valve voltage or valve current. Background technique [0002] With the advantages of large transmission capacity, fast and flexible power regulation, high reliability, and strong asynchronous connection ability, HVDC has played an increasingly important role in long-distance large-capacity power transmission and large-area grid interconnection in recent years. [1-3] . Commutation failure is one of the most common and unique faults in HVDC systems, which will lead to consequences such as DC voltage drop, DC current sudden increase, and DC transmission power reduction. If timely and effective control measures cannot be taken, subsequent commutation failures will also be caused , or even DC blocking, which threatens the safe and stable operation of the entire AC and DC system [4-5] . [0003] Rapid and accurate diagnosis of commutation failure is the premise of taki...

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Problems solved by technology

Literature [6] believes that commutation failure will occur only when the arc extinguishing angle is less than the intrinsic limit arc extinguishing angle, and the valve current and valve voltage are continuously zero, but this view is conservative. In principle, three conditions are satisfied: It can be judged as commutation failure when any one of the conditions is met; literature [7] deduced in detail the calculation formula of the minimum voltage drop required to cause commutation failure under symmetrical and asymmetrical faults, but the critical value is assumed to be AC ​​system Under the premise of infinity, based on the quasi-steady-state equation of the converter, the influence of voltage waveform distortion on commutation failure during the fault period is ignored in the derivation process, and the accuracy is poor; literature [8] combines commutation angle with commutation The phase process is analyzed, and the quantitative relationship between the commutation voltage time area and the commutation failure is obtained, but it is assumed that the commutation voltage is a sinusoidal value, and the DC current and firing angle are constant during the fault period; literature [9] pointed out that by analyzing The wavelet analysis of DC current and commutation bus voltage can not only effectively diagnose the occurrence of commutation failure, but also distinguish the types of faults that lead to commutation failure. However, the setting of the threshold and criterion is related to the structure and parameters of the system , the algorithm is more complicated, and the engineering implementation is difficult

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