Generator rotor excitation winding fault on-line multiple monitoring and early warning system

Abstract

The utility model discloses an on-line multiple monitoring and early warning system for generator rotor exciting winding faults, and belongs to the technical field of power equipment. The system comprises an electrical quantity calculation module, a detection coil module, a vibration monitoring module, an alarm module and a monitoring server. At least one of the electrical quantity calculation module, the detection coil module and the vibration monitoring module is connected with the alarm module and the monitoring server to form a fault on-line monitoring system; the electrical quantity calculation module is used for collecting data, calculating excitation current and judging whether a rotor excitation winding fault exists or not; the detection coil module is used for measuring a motor air-gap magnetic field radial component; the vibration monitoring module is used for monitoring the vibration condition of the multi-end bearing bush; the alarm module is used for delayed alarm; and the monitoring server is used for logically defining the alarm signal and outputting a monitoring result. The generator rotor excitation winding fault early warning device can accurately and sensitively monitor and early warn generator rotor excitation winding faults, avoids serious consequences caused by fault development, and improves safety and reliability of an electric power system.

Description

Technical Field

[0001] The utility model belongs to the technical field of power equipment, and particularly relates to an on-line multiple monitoring and early warning system for generator rotor excitation winding faults. Background Technique

[0002] In modern power systems, generators, as the core equipment for power production, the stability and reliability of their operation are crucial for the safe operation of the entire power grid. The generator rotor excitation winding is an important part of the generator, and its function is to provide a stable magnetic field to drive the generator to generate electrical energy. However, during actual operation, due to various factors such as material aging, mechanical wear, and electrical load fluctuations, various faults such as short circuits, open circuits, and overheating may occur in the rotor excitation winding, thereby affecting the normal operation of the generator and even causing serious safety accidents.

[0003] Traditional methods for monitoring generator rotor excitation winding faults usually rely on regular manual inspections and off-line tests. This method is not only inefficient but also difficult to detect potential fault hazards in a timely manner.

[0004] In recent years, the rapid development of sensor and data processing technologies has provided a feasible solution for the accurate and sensitive early warning of generator rotor excitation winding faults. By installing various sensors, it is possible to collect the operation data of the rotor excitation winding in real time from electrical, structural, and mechanical perspectives. At the same time, using high-performance data processing algorithms, these data are analyzed in real time to judge the operation status of the excitation winding. However, most of the existing generator rotor excitation winding fault monitoring systems currently have problems such as single monitoring parameters, low diagnostic accuracy, and poor user freedom, and it is difficult to adapt to diverse application scenarios. Therefore, there is an urgent need to develop an on-line multiple monitoring and early warning system for generator rotor excitation winding faults to achieve high-accuracy monitoring, high-sensitivity early warning, and flexible user logic definition of the excitation winding. Content of the Utility Model

[0005] Aiming at the above problems existing in the prior art, the purpose of the utility model is to provide an on-line multiple monitoring and early warning system for generator rotor excitation winding faults, which can early warn and handle generator rotor excitation winding faults.

[0006] The utility model provides the following technical solution: An on-line multiple monitoring and early warning system for generator rotor excitation winding faults, comprising an electrical quantity calculation module, a detection coil module, a vibration monitoring module, an alarm module, and a monitoring server; at least one of the electrical quantity calculation module, the detection coil module, and the vibration monitoring module is connected to the alarm module and the monitoring server to form an integrated system;

[0007] The electrical quantity calculation module is used for data acquisition, excitation current calculation and determination of whether there is a fault in the rotor excitation winding; the detection coil module is used for measuring the radial component of the air-gap magnetic field of the motor; the vibration monitoring module is used for monitoring the vibration of multiple bearing pads; the alarm module is used for delayed alarm; the monitoring server is used for logical definition of alarm signals and output of monitoring results.

[0008] Further, the electrical quantity calculation module includes a voltage and current acquisition module, an excitation current calculation module and an electrical condition judgment module; connections are made between the voltage and current acquisition module and the excitation current calculation module, between the voltage and current acquisition module and the electrical condition judgment module, and between the excitation current calculation module and the electrical condition judgment module to achieve data transmission between modules;

[0009] The voltage and current acquisition module uses the existing generator protection device to obtain the actual generator terminal voltage, terminal current and excitation current;

[0010] The excitation current calculation module is an integrated functional module, which interpolates and calculates the theoretical excitation current under the same working condition based on the no-load characteristic fitting curve of the generator and according to the actual generator terminal voltage and terminal current;

[0011] The electrical condition judgment module judges whether there is a fault in the rotor excitation winding from an electrical perspective by performing instantaneous quantity threshold comparison on the data sent by the voltage and current acquisition module and the excitation current calculation module and based on the calculation of electrical quantities.

[0012] Further, the detection coil module includes a group of detection coils and a pulse processing device; the detection coils extend into the motor air gap through the cooling air ducts of the generator stator, with the axes of the detection coils placed coincident with the motor radial direction for measuring the radial component of the motor air-gap magnetic field; the detection coils are evenly distributed in a circle along the central axis of the generator stator-rotor structure according to the stator-rotor structure and cooling air ducts of the generator, and the distribution angle is 360° / n, where n is the number of detection coils; the pulse processing device performs threshold comparison on the periodic pulse voltages from a group of detection coils through time integration and is connected to the alarm module and the monitoring server; it judges whether there is a fault in the rotor excitation winding from a structural perspective based on the distribution of the detection coils.

[0013] Further, the vibration monitoring module includes a vibration sensor and a vibration processing device; the vibration sensors are distributed at the excitation end and the turbine end bearing pads on both sides of the generator bearing, and multiple vibration sensors are installed at each vibration monitoring point; the vibration processing device performs time integration calculation, vibration attenuation compensation and threshold comparison on the continuous voltage signals generated by the vibration sensors at the same end and is connected to the alarm module and the monitoring server; it judges whether there is a fault in the rotor excitation winding from a mechanical perspective based on the vibration of the generator bearing.

[0014] Further, the monitoring server is used for aggregating, storing, calculating and comparing the data of each module, defining the logic of the alarm signals of each module and outputting the monitoring results.

[0015] By adopting the above technologies, compared with the prior art, the beneficial effects of the present utility model are as follows:

[0016] 1) The present utility model can accurately and timely monitor and warn of the faults of the generator rotor excitation winding, avoid the serious consequences caused by the development of the faults, and improve the safety and reliability of the power system;

[0017] 2) In the present utility model, through the arranged electrical quantity calculation module, detection coil module and vibration monitoring module, the three can be used independently or in cooperation, and the logic of the alarm signals can be customized, effectively realizing the balance between the diagnostic accuracy and sensitivity, improving the selectivity of the detection module, and meeting the diverse needs of different users;

[0018] 3) In the present utility model, the arranged electrical quantity calculation module, based on the quantitative relationship between the magnetic potential and the electric potential, can judge whether there is a fault in the rotor winding from the electrical angle according to the actually detected generator terminal voltage, terminal current, excitation current data and the calculated theoretical excitation current;

[0019] 4) The detection coil module set in the present utility model, based on the principle that the magnetic flux passing through the coil will periodically alternate with the position swept by the rotor slot, can accurately detect the potential faults on the generator excitation winding from the structural angle and has the function of fault location;

[0020] 5) The vibration monitoring module set in the present utility model adopts multi-point monitoring of multi-terminal bearings, can diagnose faults from the mechanical angle, and effectively avoids the occurrence of vibration false alarms. Description of the Drawings

[0021] Figure 1 It is a schematic diagram of the generator excitation constant voltage closed-loop regulation system of the present utility model;

[0022] Figure 2 It is a schematic diagram of the installation of the detection coil of the present utility model;

[0023] Figure 3 It is a schematic diagram of the layout of the vibration sensor monitoring points of the present utility model;

[0024] Figure 4 It is a system block diagram of the present utility model. Detailed Embodiment

[0025] In order to make the objectives, technical solutions and advantages of the present utility model more clearly understood, the present utility model will be further described in detail below in conjunction with the specification drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model.

[0026] On the contrary, the present utility model covers any substitutions, modifications, equivalent methods and solutions made within the essence and scope of the present utility model as defined by the claims. Further, in order to enable the public to have a better understanding of the present utility model, in the following detailed description of the present utility model, some specific details are described in detail. Those skilled in the art can fully understand the present utility model without the description of these details.

[0027] Please refer to Figures 1-4 , an online multiple monitoring and early warning system for generator rotor excitation winding faults, which is characterized by including an electrical quantity calculation module, a detection coil module, a vibration monitoring module, an alarm module and a monitoring server.

[0028] Specifically, the working principle of the electrical quantity calculation module is as follows:

[0029] When the generator is running normally, the excitation magnetomotive force can be approximately considered as a stepped or trapezoidal distribution in space. When a fault occurs in the generator rotor excitation winding, due to the reduction of the effective number of turns of the rotor excitation winding, the local excitation magnetomotive force is missing, which will cause the generator voltage to decrease. At this time, the generator excitation constant voltage closed-loop regulation system will inevitably increase the excitation current to compensate for the shortage of the excitation magnetomotive force caused by the inter-turn short circuit of the rotor, as Figure 1 shown in the schematic diagram of the generator excitation constant voltage closed-loop regulation system. Therefore, by using the quantitative relationship between the magnetomotive force and the electromotive force, accurately calculate the excitation current required for the current working condition and the measured excitation current. If the difference between the two is large, it can be determined that a fault has occurred in the rotor excitation winding.

[0030] The electrical quantity calculation module includes a voltage and current acquisition module, an excitation current calculation module and an electrical condition judgment fault diagnosis module.

[0031] The voltage and current acquisition module uses the existing generator protection device to obtain the actual generator terminal voltage, terminal current and excitation current I f .

[0032] The excitation current calculation module is internally provided with a generator no-load characteristic fitting curve, and according to the actual generator terminal voltage and terminal current, the theoretical excitation current I ft is interpolated and calculated under the same working condition.

[0033] The electrical condition judgment module determines whether there is a fault in the rotor excitation winding from an electrical perspective by comparing the data sent by the voltage and current acquisition module and the excitation current calculation module with the instantaneous quantity threshold.

[0034] Specifically, the judgment process includes the following four conditions:

[0035] 1) The deviation between the actual excitation current and the theoretical excitation current exceeds the threshold: |I f -I ft |>ε1, where I f is the actual excitation current, I ft is the theoretical excitation current, and ε1 is the differential threshold;

[0036] 2) The positive sequence component of the terminal voltage is within a reasonable range: 0.85U rate <U p <1.1U rate , where U p is the positive sequence component of the terminal voltage, and U rate is the rated value of the terminal voltage;

[0037] 3) The negative sequence component of the terminal voltage is less than the safety upper limit: U n <U set , where U n is the negative sequence component of the terminal voltage, and U set is the negative sequence safety upper limit of the terminal voltage;

[0038] 4) The three-phase terminal currents do not exceed the safety upper limit: max{I a ,I b ,I c}<1.25I rate , where I a 、I b 、I c are the three-phase terminal currents respectively, and I rate is the rated value of the terminal current.

[0039] During the judgment process, condition 1) is the action condition, and conditions 2) - 4) are the blocking conditions. After conditions 2) - 4) are satisfied, judge 1); when condition 1) is satisfied and the duration reaches the delay time t1 of the alarm module, the alarm signal is sent to the monitoring server. Among them, t1 is usually set to 10 - 20 seconds.

[0040] Specifically, the installation position of the detection coil is as Figure 2As shown in the figure, its working principle is as follows: The detection coil extends into the motor air gap through the cooling air duct of the generator stator, and the axis of the detection coil is placed coincident with the radial direction of the motor to achieve the measurement of the radial component of the motor air gap magnetic field. When the generator rotor rotates normally, the magnetic flux passing through the detection coil will change periodically with the position swept by the rotor slots, causing the pulse voltage induced on the detection coil to also change accordingly. If a fault occurs in the rotor excitation winding, the excitation magnetic field will deflect by a certain angle, resulting in different magnetic induction intensities generated when the two rotor slots on the opposite side sweep through the same coil, and further causing the voltage of the detection coil to be inconsistent in magnitude. Based on this, it can be judged whether there is a fault in the rotor excitation winding, and the rotor slot corresponding to the position where the envelope line drops can be accurately located as the faulty slot.

[0041] According to the stator and rotor structure of the generator and the design of the cooling air duct, a set of evenly distributed detection coils are selected for installation to achieve effective monitoring. Usually, 2 or 4 detection coils are selected. The distribution angle of the detection coils is 360° / n, where n is the number of detection coils. The periodic pulse voltages generated by a set of detection coils are sent to the pulse processing device, and threshold comparison is performed through time integration to judge whether there is a fault in the rotor excitation winding from a structural perspective.

[0042] In the specific judgment process, the alarm trigger condition for a single detection coil is as follows:

[0043]

[0044] In the formula, T1 is the detection period, U coil(k) is the pulse voltage when the kth rotor slot sweeps through the detection coil, U coil(m-k) is the pulse voltage when the (m - k)th rotor slot sweeps through the same detection coil, m is the total number of rotor slots, the kth rotor slot and the (m - k)th rotor slot are distributed on the opposite side, and ε2 is the pulse threshold.

[0045] In the judgment process, when the detection results of 2 or more detection coils all meet the alarm trigger condition, and the duration reaches the delay time t2 of the alarm module, the alarm signal is sent to the monitoring server. Among them, t2 is usually set to 5 - 10 minutes.

[0046] Specifically, as shown in Figure 3 the figure, vibration monitoring points are set at the bearing bush of the excitation end and the turbine end on both sides of the generator bearing. Two vibration sensors are installed at each vibration monitoring point. The continuous voltage signals generated by the vibration sensors at the same end are sent to the vibration processing device for time integration calculation, vibration attenuation compensation, and threshold comparison to judge whether there is a fault in the rotor excitation winding from a mechanical perspective. When the value calculated by the vibration processing device is greater than the upper limit of the vibration threshold, an alarm is triggered, and the upper limit of the vibration threshold is set separately according to the power level structure of each generator.

[0047] In the specific judgment process, the alarm trigger conditions of the vibration monitoring module are as follows:

[0048]

[0049] where U exc1 and U exc2 are respectively the voltage signals of two vibration sensors installed at the shaft bearing of the generator excitation end. U exc is the stable voltage setting value of the vibration sensor at the excitation end under normal operation. U ste1 and U ste2 are respectively the voltage signals of two vibration sensors installed at the shaft bearing of the turbine end. U ste is the stable voltage setting value of the vibration sensor at the turbine end under normal operation. T2 is the vibration period, α1 and α2 are respectively the vibration attenuation coefficients of the excitation end and the turbine end, x1 and x2 are respectively the shaft distances from the shaft bearings of the excitation end and the turbine end to the excitation winding of the generator rotor, and ε3 is the vibration threshold.

[0050] During the judgment process, when the vibration monitoring module meets the alarm trigger conditions and the duration reaches the delay time t3 of the alarm module, the alarm signal will be sent to the monitoring server. Among them, t3 is usually set to 10 - 30 minutes.

[0051] Specifically, according to their own needs, as Figure 4 shown, users can select the electrical quantity calculation module, the detection coil module or the vibration monitoring module individually, or they can also select them in combination according to their own needs to meet the diverse needs of users. At the same time, when two or more modules are put into use, users can customize the "AND" and "OR" logical relationships of the alarm signals of the monitoring modules to achieve the balance of the accuracy and sensitivity of the fault diagnosis of the rotor excitation winding. Table 1 shows the performance characteristics of the online multi - monitoring and early warning system for the fault of the generator rotor excitation winding when the three modules are put into use respectively and different logical definitions are adopted.

[0052] Table 1

[0053]

[0054] The above are only the preferred embodiments of the present invention, and are not used to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. An on-line multi-monitoring and early warning system for faults in the excitation winding of a generator rotor, characterized in that, It includes an electrical quantity calculation module, a detection coil module, a vibration monitoring module, an alarm module and a monitoring server; at least one of the electrical quantity calculation module, the detection coil module and the vibration monitoring module is connected to the alarm module and the monitoring server to form an integrated system; The electrical quantity calculation module is used for data acquisition, excitation current calculation and judging whether there is a fault in the rotor excitation winding; the detection coil module is used for measuring the radial component of the air-gap magnetic field of the motor; the vibration monitoring module is used for monitoring the vibration conditions of multi-terminal bearings; the alarm module is used for delayed alarm; the monitoring server is used for logical definition of alarm signals and outputting monitoring results.

2. An on-line multiple monitoring and early warning system for generator rotor excitation winding faults according to claim 1, characterized in that The electrical quantity calculation module includes a voltage and current acquisition module, an excitation current calculation module and an electrical condition judgment fault diagnosis module; the voltage and current acquisition module is connected to the excitation current calculation module, the voltage and current acquisition module is connected to the electrical condition judgment fault diagnosis module, and the excitation current calculation module is connected to the electrical condition judgment fault diagnosis module to realize data transmission between modules; The voltage and current acquisition module is used for obtaining the actual generator terminal voltage, terminal current and excitation current; The excitation current calculation module is used for obtaining the excitation current required under the current working condition; The electrical condition judgment module judges whether there is a fault in the rotor excitation winding based on the calculation of electrical quantities.

3. An on-line multi-monitoring and early warning system for generator rotor excitation winding faults according to claim 2, characterized in that, The detection coil module includes a group of detection coils and a pulse processing device for judging whether there is a fault in the rotor excitation winding based on the distribution of the detection coils; the detection coils extend into the motor air gap through the cooling air duct of the generator stator, and the axes of the detection coils are placed coincident with the motor radial direction; a group of detection coils are evenly distributed in a circle along the central axis of the generator stator-rotor structure; the pulse processing device is connected to the monitoring server through the alarm module.

4. An on-line multiple monitoring and early warning system for generator rotor excitation winding faults. An on-line multiple monitoring and early warning system for generator rotor excitation winding faults, characterized in that, The vibration monitoring module includes a vibration sensor and a vibration processing device for judging whether there is a fault in the rotor excitation winding based on the vibration of the generator bearing; the vibration sensors are distributed at the excitation end and the turbine end bearings on both sides of the generator bearing, and a group of vibration sensors are installed at each vibration monitoring point; the vibration processing device is connected to the monitoring server through the alarm module.

5. An on-line multi-monitoring and early warning system for faults in the excitation winding of a generator rotor. An on-line multi-monitoring and early warning system for faults in the excitation winding of a generator rotor is characterized in that, The monitoring server is used for the aggregation, storage, calculation and comparison of data of each module, for logical definition of alarm signals of each module and outputting monitoring results.

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