CN-122017671-A - Diode open-circuit fault online detection method for multi-pulse transformer rectifier

CN122017671ACN 122017671 ACN122017671 ACN 122017671ACN-122017671-A

Abstract

The invention relates to a method based on Method for online detection of open circuit faults of diodes of rectifier bridge in track multi-pulse variable-voltage rectifier according to primary side current of variable-voltage rectifier The near-circular rate of the trace and the normalized trace center offset detect the open circuit of the rectifier bridge/diodes in the multi-pulse transformer rectifier on line. The three-phase primary side steady-state current of the phase-shifting transformer is subjected to whole-period phase alignment window cutting and then is subjected to average treatment, and calculation is carried out The current amplitude and phase in the coordinate system obtain a trace graph. According to The trace diagram calculates the near-circle rate and the normalized trace center offset, and is used for judging whether the diodes in the multi-pulse transformer rectifier have open-circuit faults or not, and comparing with a predefined criterion threshold value, further judging whether the open-circuit of the diodes occurs in the same rectifier bridge or different rectifier bridges. The detection method can realize on-line monitoring, is easy to realize engineering, and does not need to install an additional detection circuit.

Inventors

WANG TING
LI WEI
LI WEILIN
ZHANG XIAOBIN

Assignees

西北工业大学

Dates

Publication Date: 20260512
Application Date: 20260206

Claims (4)

1. The online detection method for the open circuit fault of the diode of the multi-pulse transformer rectifier is characterized by comprising the following steps of: Step 1, calculating Current sequence under the coordinate system and drawing the track: For three-phase primary steady-state current of phase-shifting transformer 、、 Carrying out phase alignment windowing and averaging treatment on the whole period to obtain 、、 Obtaining the product through Clark transformation Current sequence in coordinate system And Wherein Drawing and painting A track; Step 2, calculating The characteristic quantity of the track comprises the track center coordinates and the distance from the track to the origin of coordinates: Calculating the sequence of the central angles of the tracks Wherein ; Calculating a sequence of distances from a trajectory to an origin of coordinates Wherein ; Calculating the center coordinates of the track ; Step 3, calculating Track near-circle rate and normalized track center offset: calculating a near-circular rate from the current sequence , Wherein P is the perimeter of the track, which is obtained by accumulating the side lengths, and the specific formula is as follows: ; A is the track area, which is obtained by using a triangulation method, and the specific formula is as follows: ; calculating the average value of the characteristic quantity And Calculating to obtain the normalized track center offset ; Step 4, giving a threshold value And And (3) with And And comparing and judging whether faults occur, and if two or more diodes fail, determining that the failed diodes are positioned in the same rectifier bridge or different rectifier bridges.
2. The method for online detection of open circuit faults of diodes of a multi-pulse transformer rectifier according to claim 1, wherein the calculation in the step 3 is realized through codes imported into a register.
3. The online detection method of open circuit faults of diodes of a multi-pulse transformer rectifier according to claim 1, wherein the fault judgment flow in the step 4 is as follows: If the rate is near the circle And the normalized track center offset If the multi-pulse transformer rectifier has no diode, the multi-pulse transformer rectifier has no diode open-circuit fault, otherwise, the multi-pulse transformer rectifier has the diode open-circuit fault; Further, if And is also provided with And is also provided with An open circuit fault occurs in a single diode in the multi-pulse transformer rectifier; If it is But is provided with And If either one or both of the two conditions are not met, then the open circuit fault occurs at the same time in the multi-pulse rectifier bridge by two or more diodes which are not in phase with the rectifier bridge; Further, if Is not true, and The open circuit fault occurs at the same time in the multi-pulse rectifier bridge with two or more diodes in phase with the rectifier bridge; If it is Is not true, and If not, then the open circuit fault occurs simultaneously for two or more diodes of different rectifier bridges in the multi-pulse rectifier bridge.
4. The online detection method for open circuit faults of diodes of a multi-pulse transformer rectifier according to claim 3, characterized in that The value range of (2) is adjusted according to the practical application object, the The value range is 0.01-0.05.

Description

Diode open-circuit fault online detection method for multi-pulse transformer rectifier Technical Field The invention belongs to the field of detection of power electronic systems, and particularly relates to an online detection method for open-circuit faults of diodes of a multi-pulse transformer rectifier. Background The operation reliability of the multi-pulse transformer rectifier serving as a key energy conversion device in an aviation power supply system, a rail transit traction power supply system, a ship power system and an industrial direct current bus is directly related to the safety and usability of the system. In these applications, which are often operated in high current, high temperature, frequent load fluctuations, and complex electromagnetic environments for long periods of time, the diode is inevitably subjected to large thermal and electrical stresses. In actual engineering operation, diode faults are one of the most common and most concealed fault modes in a multi-pulse transformer rectifier. Unlike short circuit faults, diode opens often do not immediately trigger protection actions or system shutdowns, but rather evolve gradually in the form of "performance degradation", being more concealed and difficult to detect quickly. Extensive engineering experience has shown that a single diode open is not generally the final fault morphology, but rather the initial phase of a multi-diode open fault. After the single diode is opened, the current corresponding to the conduction interval is instantaneously and rapidly redistributed to other diodes of the same bridge arm or adjacent bridge arms, so that the devices bear larger transient peak current and thermal load, and finally evolve into a plurality of open diodes, thereby causing serious potential safety hazards such as direct current voltage drop, electromagnetic interference aggravation, overheating of an upstream transformer and the like. Therefore, from the engineering safety and the post maintenance perspective, it is far from enough to pay attention to only a single diode open circuit, and a detection method capable of covering multiple diode open circuits and having practical guiding significance for post maintenance replacement is needed. The current literature is directed to the study of diode opens in a multi-pulse transformer rectifier, mostly focusing on single diode open conditions, and relying mainly on direct current component and harmonic analysis. Although the direct current component can directly reflect faults, the direct current component is not suitable for the occasion which is easy to be interfered, for example, the characteristics of multiple loads, rapid change of working conditions and the like in the industrial direct current bus can cause misjudgment of diode open circuit detection based on the direct current component. Furthermore, there is often overlap of harmonic features in different failure modes, resulting in failure indistinguishable. But is based onThe detection method of the space domain maps the one-dimensional fault characteristics to the two-dimensional space and derives more geometric characteristics. The characteristics can intuitively reflect various symmetrical faults of the multi-pulse transformer rectifier, have stronger robustness and are more suitable for being applied under complex and dynamic working conditions. Therefore, from the point of view of detecting various open circuit faults and engineering versatility, the present patent utilizesThe diagnosis of the transformer rectifier diode open circuit by the track has obvious advantages and has practical necessity in the multi-diode open circuit high-risk application. Disclosure of Invention The invention aims to provide an online detection method for open-circuit faults of diodes of a multi-pulse transformer rectifier, which comprises the following steps: Step 1, calculating Current sequence under the coordinate system and drawing the track: For three-phase primary steady-state current of phase-shifting transformer 、、Carrying out phase alignment windowing and averaging treatment on the whole period to obtain、、Obtaining the product through Clark transformationCurrent sequence in coordinate systemAndWhereinDrawing and paintingA track. Step 2, calculatingThe characteristic quantity of the track comprises the track center coordinates and the distance from the track to the origin of coordinates: Calculating the sequence of the central angles of the tracks Wherein; Calculating a sequence of distances from a trajectory to an origin of coordinatesWherein; Calculating the center coordinates of the track。 Step 3, calculatingTrack near-circle rate and normalized track center offset: calculating a near-circular rate from the current sequence ; Wherein P is the perimeter of the track, which is obtained by accumulating the side lengths, and the specific formula is; A is the track area, which is obtained by triangulation method, and the specific formula is。