阅读说明：本技术 一种同步调相机定子绕组故障检测和辨别的方法 (Method for detecting and distinguishing stator winding faults of synchronous phase modulator ) 是由 王伟 李环宇 杨超伟 蔚超 程明 于 2021-10-19 设计创作，主要内容包括：本发明公开一种同步调相机定子绕组故障检测和辨别的方法,属于故障诊断技术领域,该方法主要包括对同步调相机定子绕组中性点电压进行采样,得到中性点电压,然后利用中性点电压和电网三相电压得到零序电压,再利用频率跟踪算法提取零序电压中基频幅值,将零序电压中基频分量的幅值与阈值作比较以检测定子绕组是否发生故障等步骤；本发明诊断方法通过在检测出故障后,调节励磁电流大小以减小三相定子电流大小,不仅可以精确辨别出故障类型,还可以减小故障对电机系统的危害。(The invention discloses a method for detecting and distinguishing faults of stator windings of a synchronous phase modulator, which belongs to the technical field of fault diagnosis and mainly comprises the steps of sampling neutral point voltage of the stator windings of the synchronous phase modulator to obtain neutral point voltage, then obtaining zero sequence voltage by utilizing the neutral point voltage and three-phase voltage of a power grid, extracting fundamental frequency amplitude in the zero sequence voltage by utilizing a frequency tracking algorithm, comparing the amplitude of fundamental frequency components in the zero sequence voltage with a threshold value to detect whether the stator windings have faults or not and the like; the diagnosis method of the invention reduces the three-phase stator current by adjusting the exciting current after detecting the fault, not only can accurately distinguish the fault type, but also can reduce the damage of the fault to the motor system.)

1. A method of synchronous phase modulator stator winding fault detection and discrimination, said method comprising the steps of:

s1: sampling the neutral point voltage of the stator winding of the synchronous phase modulator to obtain a neutral point voltage V₀；

S2: obtaining zero sequence voltage V by using neutral point voltage and three-phase voltage of power grid_0m；

S3: extracting fundamental frequency amplitude V in zero sequence voltage by using frequency tracking algorithm_0m1；

S4: comparing the fundamental frequency amplitude V_0m1And its threshold value V_0m1thIf the fundamental frequency amplitude is larger than the threshold value, the fault of the stator winding is detected, and the fundamental frequency amplitude at the moment is recorded as V_0m1,1；

S5: adjusting exciting current of synchronous phase modulator to reduce three-phase stator current, and extracting zero-sequence voltage fundamental frequency amplitude V at the moment by using frequency tracking algorithm_0m1,2；

S6: obtaining a fault discrimination index DI by taking the zero sequence voltage fundamental frequency amplitude values obtained by the two extractions as a quotient;

s7: comparing the fault discrimination indicator DI with its threshold DI_thIf the fault discrimination index is larger than the threshold value, the fault is a stator winding resistance unbalance fault, otherwise, the fault is a stator winding turn-to-turn short circuit fault.

2. The method of claim 1, wherein said zero sequence voltage V at S2 is used for detecting and distinguishing stator winding fault_0mThe calculation formula of (a) is as follows:

wherein, V₀Is neutral point voltage, V_a、V_b、V_cThe stator windings are respectively three-phase voltages.

3. The method of claim 1, wherein said amplitude of fundamental frequency V of S3 is zero sequence voltage amplitude_0m1The calculation steps are as follows:

1) zero sequence voltage V_0mConversion to a rotating coordinate system:

wherein, ω is_eFor synchronizing the electromechanical angular velocity of the phase modulator, t' is the running time of the fault detection and discrimination algorithm, θ_eIs the rotor electrical angle, beta is omega_et' and theta_eThe difference in angle of (a).

2) Obtaining V under a rotating coordinate system by using a low-pass filter_d' and V_q'direct current component V'_d1And V'_q1The expressions are respectively as follows:

wherein, alpha is the initial phase angle of the fundamental frequency component of the zero-sequence voltage.

3) Calculating the fundamental frequency amplitude V of the zero sequence voltage_0m1：

4. The method of detecting and discriminating stator winding fault of synchronous phase modulator according to claim 1, wherein said fault discrimination indicator DI in S6 is calculated as follows:

5. the method of stator winding fault detection and discrimination for synchronous phase modulators of claim 1, wherein the threshold values of the fault discrimination indicator DI in S7 are set as follows:

wherein, I_a1,1For adjusting the amplitude of the fundamental component of the A-phase current before the exciting current, I_a1,2In order to adjust the amplitude of the fundamental frequency component of the A-phase current after the exciting current, the rest is analogized.

Technical Field

The invention relates to the technical field of fault diagnosis, in particular to a method for detecting and distinguishing faults of stator windings of a synchronous phase modulator.

Background

Energy resources and power loads in China are distributed in a reverse direction, and an extra-high voltage direct-current transmission system is rapidly developed and widely applied. In order to solve the outstanding problems of insufficient dynamic reactive power supply of an ultrahigh-voltage DC receiving end, weaker voltage supporting capability and the like, the novel high-capacity synchronous phase modulator is applied. The large motor reliability reports indicate that more than 40% of faults in synchronous motors are stator winding faults, and that stator winding early faults can be divided into inter-turn short circuit faults and resistance imbalance faults. Turn-to-turn short faults occur because the insulation between turns of the winding is broken. The resistance unbalance fault refers to a fault that the resistance of a certain phase is increased and the inductance is unchanged, and the fault is related to the damage of welding spots between windings.

Many fault diagnosis researches aiming at stator winding turn-to-turn short circuit and stator winding resistance unbalance faults exist, but most fault diagnosis methods need known fault types. In practical application, the fault type cannot be known in advance, so that the fault identification research on the fault motor is significant. At present, the research on the discrimination of the faults of the turn-to-turn short circuit of the stator winding and the unbalanced resistance of the stator winding is very little, and the methods are mostly concentrated on the permanent magnet synchronous motor, but the operation mode of the synchronous phase modulator is greatly different from that of the permanent magnet synchronous motor, so the fault discrimination research needs to be carried out aiming at the faults of the turn-to-turn short circuit of the stator winding and the unbalanced resistance of the stator winding of the synchronous phase modulator.

Disclosure of Invention

The invention aims to provide a method for detecting and distinguishing faults of stator windings of a synchronous phase modulator, which detects whether the stator windings of the synchronous phase modulator have faults or not by monitoring the amplitude of fundamental frequency components of zero-sequence voltage, reduces the magnitude of three-phase current of the stator by adjusting exciting current after the stator windings of the synchronous phase modulator are detected to have the faults, obtains the amplitude of the fundamental frequency components of the zero-sequence voltage at the moment, obtains a fault distinguishing index by using the amplitudes of the fundamental frequency components of the zero-sequence voltage obtained twice as a quotient, and finally judges whether the synchronous phase modulator has a stator winding turn-to-turn short circuit fault or a stator winding resistance imbalance fault by using the fault distinguishing index. The method can realize rapid fault detection and accurate fault discrimination, and is convenient and rapid.

The purpose of the invention can be realized by the following technical scheme:

a method for detecting and distinguishing stator winding faults of a synchronous phase modulator mainly comprises the following steps:

s1: sampling the neutral point voltage of the stator winding of the synchronous phase modulator to obtain a neutral point voltage V₀；

S2: obtaining zero sequence voltage V by using neutral point voltage and three-phase voltage of power grid_0m；

S3: extracting fundamental frequency amplitude V in zero sequence voltage by using frequency tracking algorithm_0m1；

S4: comparing the fundamental frequency amplitude V_0m1And its threshold value V_0m1thIf the fundamental frequency amplitude is larger than the threshold value, the fault of the stator winding is detected, and the fundamental frequency amplitude at the moment is recorded as V_0m1,1；

S5: adjusting exciting current of synchronous phase modulator to reduce three-phase stator current, and extracting zero-sequence voltage fundamental frequency amplitude V at the moment by using frequency tracking algorithm_0m1,2；

S6: obtaining a fault discrimination index DI by taking the zero sequence voltage fundamental frequency amplitude values obtained by the two extractions as a quotient;

s7: comparing the fault discrimination indicator DI with its threshold DI_thIf the fault discrimination index is larger than the threshold value, the fault is a stator winding resistance unbalance fault, otherwise, the fault is a stator winding turn-to-turn short circuit fault.

The invention has the beneficial effects that:

1. the invention detects whether the stator winding of the synchronous phase modulator has a fault by monitoring the amplitude of the fundamental frequency component of the zero-sequence voltage, reduces the size of the three-phase current of the stator by adjusting the exciting current after detecting that the stator winding of the synchronous phase modulator has the fault, obtains the amplitude of the fundamental frequency component of the zero-sequence voltage at the moment, obtains a fault discrimination index by quoting the amplitude of the fundamental frequency component of the zero-sequence voltage obtained twice, and finally judges whether the synchronous phase modulator has a turn-to-turn short circuit fault of the stator winding or a resistor unbalance fault of the stator winding by utilizing the fault discrimination index.

2. According to the invention, after the fault is detected, the size of the exciting current is adjusted to reduce the size of the three-phase stator current, so that not only can the fault type be accurately distinguished, but also the damage of the fault to a motor system can be reduced.

Drawings

In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present invention, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.

FIG. 1 is an equivalent model diagram of a stator winding turn-to-turn short circuit fault (the fault occurs in phase A) of a synchronous phase modulator according to the present invention;

FIG. 2 is an equivalent model diagram of the stator winding resistance imbalance fault (the fault occurs in phase A) of the synchronous phase modulator of the present invention;

FIG. 3 is a fault detection and discrimination flow chart of the present invention;

FIG. 4 is a diagram showing the variation of the amplitude of the fundamental frequency component of the zero-sequence voltage in case of a turn-to-turn short circuit fault of the stator winding of the synchronous phase modulator according to the present invention;

FIG. 5 shows the variation of the amplitude of the fundamental frequency component of the zero-sequence voltage in the case of unbalanced resistance of the stator winding of the synchronous phase modulator.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The present embodiment is directed to a synchronous phase modulator, and fig. 1 and 2 are equivalent model diagrams when a turn-to-turn short circuit (fault occurs in phase a) and a resistance imbalance fault (fault occurs in phase a) occur in the synchronous phase modulator, respectively. And setting the turn-to-turn short circuit fault and the resistance unbalance fault to occur at 1s, and adjusting the exciting current from 4.1A to 4.2A at 1.5 s.

A method for detecting and identifying stator winding faults of a synchronous phase modulator, as shown in fig. 3, the method mainly comprises the following steps:

s1: sampling the neutral point voltage of the stator winding of the synchronous phase modulator to obtain a neutral point voltage V₀；

S2: obtaining zero sequence voltage V by using neutral point voltage and three-phase voltage of power grid_0m(ii) a Zero sequence voltage V_0mThe calculation formula of (a) is as follows:

wherein, V₀Is neutral point voltage, V_a、V_b、V_cThe stator windings are respectively three-phase voltages.

S3: extracting fundamental frequency amplitude V in zero sequence voltage by using frequency tracking algorithm_0m1(ii) a Zero sequence voltage fundamental frequency amplitude V_0m1The calculation steps are as follows:

1) zero sequence voltage V_0mConversion to a rotating coordinate system:

wherein, ω is_eFor synchronizing the electromechanical angular velocity of the phase modulator, t' is the running time of the fault detection and discrimination algorithm, θ_eIs the rotor electrical angle, beta is omega_et' and theta_eThe difference in angle of (a).

2) Obtaining V 'in the rotation coordinate system by a low-pass filter'_dAnd V'_qOf direct current component V'_d1And V'_q1The expressions are respectively as follows:

wherein, alpha is the initial phase angle of the fundamental frequency component of the zero-sequence voltage.

3) Calculating the fundamental frequency amplitude V of the zero sequence voltage_0m1：

S4: comparing the fundamental frequency amplitude V_0m1And its threshold value V_0m1thIf the fundamental frequency amplitude is larger than the threshold value, the fault of the stator winding is detected, and the fundamental frequency amplitude at the moment is recorded as V_0m1,1；

S5: adjusting exciting current of synchronous phase modulator to reduce three-phase stator current, and extracting zero-sequence voltage fundamental frequency amplitude V at the moment by using frequency tracking algorithm_0m1,2；

S6: obtaining a fault discrimination index DI by taking the zero sequence voltage fundamental frequency amplitude values obtained by the two extractions as a quotient; the formula for the calculation of the fault discrimination indicator DI is as follows:

s7: comparing the fault discrimination indicator DI with its threshold DI_thIf the fault discrimination index is larger than the threshold value, the fault is a stator winding resistance unbalance fault, otherwise, the fault is a stator winding turn-to-turn short circuit fault; the threshold values of the fault discrimination indicator DI are set as follows:

wherein, I_a1,1For adjusting the amplitude of the fundamental component of the A-phase current before the exciting current, I_a1,2In order to adjust the amplitude of the fundamental frequency component of the A-phase current after the exciting current, the rest is analogized.

FIG. 4 is a graph showing the variation of the amplitude of the fundamental frequency component of the zero sequence voltage in case of turn-to-turn short circuit of the stator winding of the synchronous phase modulator, wherein the fundamental frequency component of the zero sequence voltage is shown after the turn-to-turn short circuit occursAmplitude of frequency component V_0m1Increases from 0 to 0.312, is greater than the threshold value V_0m1thThen, the fault of the motor stator winding can be judged, then the exciting current is adjusted, the zero sequence voltage fundamental frequency component amplitude value is not changed, the fault discrimination index DI is 1, and at the moment, the fault discrimination index threshold DI is calculated by a formula_thAt 1.184, the fault discrimination indicator DI is less than its threshold and the fault is discriminated as a stator winding turn-to-turn short fault.

FIG. 5 shows the variation of the amplitude of the fundamental frequency component of the zero sequence voltage in the unbalanced resistance fault of the stator winding of the synchronous phase modulator, and it can be seen from the diagram that the amplitude V of the fundamental frequency component of the zero sequence voltage is obtained after the unbalanced resistance fault occurs_0m1Increases from 0 to 0.283, is greater than the threshold value V_0m1thThen, the fault of the motor stator winding can be judged, then the exciting current is adjusted, the zero sequence voltage fundamental frequency component amplitude value becomes 0.228, the fault discrimination index DI is 1.241, and the fault discrimination index threshold DI calculated by a formula is obtained at the moment_thAt 1.185, the fault discrimination indicator DI is greater than its threshold, and the fault is identified as a stator winding resistance imbalance fault.

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed.