Fault point identification method of synchronous motor rotor pole coil ground short circuit fault

Abstract

The invention discloses a fault point identification method for a synchronous motor rotor pole coil ground short circuit fault, and belongs to the technical field of motor rotor fault detection. The method comprises the following steps of: 1, introducing direct current voltage between a head end lead of a pole coil and a rotor bracket, and controlling the numerical value of the direct current to be between 10%-30% of rated excitation current IN; 2, sequentially measuring the surface magnetic field intensity of each magnetic pole by using a gauss meter from one end of the electrified magnetic pole coil; and step 3, when the detected magnetic field intensity value is obviously weakened, stopping measurement, and finally determining that the fault point is on the previous magnetic pole of the magnetic pole where the magnetic field intensity value is obviously weakened. According to the invention, the coil where the fault point of the synchronous motor rotor pole coil to ground short circuit fault is located can be detected without disconnecting the connecting line between the magnetic poles, the operation of disconnecting the connecting line between the magnetic poles one by one in order to find the fault point is omitted, the working difficulty of detecting and finding the fault point during maintenance is reduced, and the maintenance efficiency is improved. And the maintenance and detection efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor rotor fault detection, and particularly relates to a method for identifying the fault point of the ground short circuit fault of the rotor pole coil of a synchronous motor. Background Art

[0002] The rotor of a salient-pole synchronous motor consists of a rotor bracket, a pole core, a pole coil, a connecting wire between poles, etc. There is an insulating layer between the pole coil and the pole core. The insulation loss between the pole coil and the pole core is a common fault point, which is caused by various reasons such as the installation of the pole coil, burrs on the pole core, and insulation aging after long-term operation. When searching for the fault point, it is usually necessary to disconnect the connecting wire between the poles and detect the insulation resistance to the ground one by one. Since the connecting wire between the poles is usually welded with a splicing sleeve, the operation of disconnecting the connecting wire between the poles is time-consuming and laborious. Especially for a synchronous motor with a large number of poles, the number of poles can reach dozens, and it is difficult to find the fault point. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for identifying the fault point of the ground short circuit fault of the rotor pole coil of a synchronous motor, which can detect the coil where the fault point of the ground short circuit fault of the rotor pole coil of the synchronous motor is located without disconnecting the connecting wire between the poles, omitting the operation of disconnecting the connecting wire between the poles one by one to find the fault point, reducing the working difficulty of detecting and finding the fault point during maintenance, and improving the maintenance and detection efficiency.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is:

[0005] A method for identifying the fault point of the ground short circuit fault of the rotor pole coil of a synchronous motor, the method comprising the following steps:

[0006] Step 1: Apply a DC voltage between the leading wire of the head end of the pole coil and the rotor bracket, and control the value of the DC current between 10% - 30% of the rated excitation current I N ;

[0007] Step 2: Starting from one end of the energized pole coil, use a gaussmeter to measure the magnetic field intensity on the surface of each pole in turn;

[0008] Step 3: Stop measuring when the detected magnetic field intensity value is significantly weakened, and finally determine that the fault point is on the previous pole of the pole where the magnetic field intensity value is significantly weakened.

[0009] Further, in step 2, the measured value of the magnetic field intensity of the first detected pole is used as a reference value and recorded.

[0010] Further, in Step 2, the measured surface magnetic field intensity values of the magnetic poles are compared with the reference values in sequence. If the measured surface magnetic field intensity value of a magnetic pole is greater than 70% of the reference value, the next magnetic pole is detected; if the measured surface magnetic field intensity value of a magnetic pole is less than 70% of the reference value, the fault point is determined to be the previous magnetic pole of the magnetic pole where the measured value is located.

[0011] The beneficial effects of the present invention compared with the prior art are as follows: The fault point identification method of the present invention can find the fault point without disconnecting the connection wires between the magnetic poles, realizing the search for the ground short - circuit fault point of the magnetic pole coil without removing and damaging the connection leads between the magnetic poles, which facilitates the fault detection. For example, for a 60 - pole synchronous motor rotor, when a ground short - circuit fault occurs in one magnetic pole, if the connection leads between the magnetic poles are removed or disconnected one by one during the search, the work is quite difficult. The present invention can find the fault point without removing and damaging the connection wires between the magnetic poles. Description of the Drawings

[0012] Figure 1 is a schematic diagram of the structure of a synchronous motor rotor.

[0013] Figure 1 The names and reference numerals of the components involved are as follows:

[0014] 1. The end lead of the magnetic pole coil 5; 2. The start lead of the magnetic pole coil 5; 3. The connection wire between the magnetic poles; 4. The magnetic pole core; 5. The magnetic pole coil.

[0015] Figure 2 is a schematic diagram of the rotor magnetic field when there is no ground short - circuit fault in the magnetic pole.

[0016] Figure 3 is a schematic diagram of the rotor magnetic field when there is a ground short - circuit fault in the magnetic pole.

[0017] Figure 4 is a flowchart of the fault point identification method for the ground short - circuit fault of the magnetic pole coil of the synchronous motor rotor of the present invention.

[0018] Figure 5 is a flowchart of the embodiment of the present invention. Detailed Embodiments

[0019] As Figures 1-4 shown, this embodiment discloses a fault point identification method for the ground short - circuit fault of the magnetic pole coil of a synchronous motor rotor. The method includes the following steps:

[0020] Step 1: Apply a DC voltage between the start lead 2 of the magnetic pole coil 5 and the rotor bracket, and control the value of the DC current within the range of 10% - 30% of the rated excitation current I N between;

[0021] Step 2: Starting from one end of the energized pole coil 5, use a gaussmeter to sequentially measure the magnetic field intensity on the surface of each pole;

[0022] Step 3: Stop measuring when the detected magnetic field intensity value significantly weakens, and finally determine that the fault point is on the previous pole of the pole where the magnetic field intensity value significantly weakens.

[0023] Further, in Step 2, take the measured magnetic field intensity value of the first detected pole as the reference value and record it.

[0024] Further, in Step 2, sequentially compare the measured surface magnetic field intensity value of the pole with the reference value. If the measured surface magnetic field intensity value of the pole is greater than 70% of the reference value, then detect the next pole; if the measured surface magnetic field intensity value of the pole is less than 70% of the reference value, then determine that the fault point is on the previous pole of the pole where the measured value is located.

[0025] Embodiment:

[0026] As Figures 1-3 and Figure 5 shown, this embodiment describes a method for identifying the fault point of a ground short circuit fault of the rotor pole coil of a synchronous motor. The method includes the following steps:

[0027] Step 1: Apply a DC voltage between the leading wire 2 of the pole coil 5 and the rotor bracket;

[0028] Step 2: Detect whether the value of the DC current is between 10% - 30% of the rated excitation current I N If the current is between 10% - 30% of the rated excitation current I N then execute Step 3; if the current is not between 10% - 30% of the rated excitation current I N then adjust the DC voltage until the current is between 10% - 30% of the rated excitation current I N ;

[0029] Step 3: Use a gaussmeter to detect the magnetic field intensity starting from the first pole on the side of the leading wire 2 of the pole coil 5, and take the measured value as the reference value and record it;

[0030] Step 4: Sequentially detect the magnetic field intensity of the poles;

[0031] Step 5: Compare the measured magnetic field intensity value of the detected pole with the reference value. If the measured magnetic field intensity value of the pole is greater than 70% of the reference value, then detect the next pole; if the measured magnetic field intensity value of the pole is less than 70% of the reference value, then determine that the fault point is on the previous pole of the pole where the measured value is located.

[0032] The method for identifying the fault point of the ground short - circuit fault of the rotor pole coil of the synchronous motor of the present invention is specifically a shutdown detection method for the ground short - circuit fault of the rotor pole coil based on the DC impedance method applied to high - efficiency and energy - saving large - scale synchronous motors. In the shutdown state of the motor, the detection can be completed without disconnecting the connection lines between the poles, which can greatly reduce the maintenance time (70% shorter than the traditional method), reduce the maintenance difficulty, lower the labor cost, and effectively ensure the detection accuracy. This technology is especially suitable for synchronous motors with an energy efficiency level of IE4 and above. While ensuring the detection accuracy, it effectively avoids the risk of insulation damage caused by the traditional point - by - point disconnection detection, and solves the problem of additional energy consumption caused by magnetic field asymmetry due to single - point short - circuit and other reasons in energy - saving motors. Taking a 2000kW - class motor as an example, a single - point short - circuit can cause the motor efficiency to drop by 3% - 5%. Through early repair, this method can save up to 80,000 kWh of electricity annually.

[0033] The above is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes, should be covered within the protection scope of the present invention.

Claims

1. A method for identifying the fault point of the ground short circuit fault of the rotor pole coil of a synchronous motor, characterized in that: The method includes the following steps: Step 1: Apply a DC voltage between the leading wire (2) at the head end of the magnetic pole coil (5) and the rotor bracket, and control the value of the DC current within the range of 10% - 30% of the rated excitation current I N ; Step 2: Starting from one end of the energized magnetic pole coil (5), use a gaussmeter to sequentially measure the magnetic field intensity on the surface of each magnetic pole; Step 3: Stop measuring when the detected magnetic field intensity value significantly weakens, and finally determine that the fault point is on the magnetic pole immediately preceding the magnetic pole where the magnetic field intensity value significantly weakens.

2. The fault point identification method according to claim 1, wherein: In Step 2, take the magnetic field intensity measurement value of the first detected magnetic pole as the reference value and record it.

3. The fault point identification method according to claim 2, characterized in that: In Step 2, sequentially compare the measured surface magnetic field intensity values of the magnetic poles with the reference value. If the measured surface magnetic field intensity value of a magnetic pole is greater than 70% of the reference value, then proceed to detect the next magnetic pole; If the measured surface magnetic field intensity value of a magnetic pole is less than 70% of the reference value, then determine that the fault point is the magnetic pole immediately preceding the magnetic pole where the measurement value is located.

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