Hydro-generator shaft insulation multi-parameter monitoring method and system

Abstract

The invention provides a hydro-generator shaft insulation multi-parameter monitoring method and system, and the method comprises the steps: employing a common excitation proportion method, introducing a high-frequency excitation current source through a grounding brush, loading a high-frequency voltage on the basis of a shaft voltage, respectively detecting an oil film voltage and an insulation pad voltage, and calculating a voltage amplitude ratio, analyzing oil film capacitance and insulation capacitance based on the high-frequency signal; a co-excitation polling method is adopted, high-frequency excitation current paths are sequentially switched through a polling device, high-frequency current flows through different impedance branches, high-frequency and low-frequency voltage signals are separated through a frequency-selecting filter, and oil film impedance and insulation impedance are analyzed; an independent excitation method is adopted, a high-frequency excitation source is independently introduced from a bearing bush, a frequency-selecting filter or an impedance converter is combined, independent measurement of oil film impedance and insulation impedance is achieved, and oil film thickness and insulation parameters are calculated. According to the invention, multi-parameter monitoring of bearing insulation can be realized.

Description

Technical Field

[0001] This application relates to the technical field of generator shaft monitoring, and particularly to a method and system for multi-parameter monitoring of the insulation of a hydro-generator shaft. Background Art

[0002] To ensure the safe operation of large hydro-generator units, parameters such as bearing insulation impedance and oil film thickness are key on-line monitoring parameters. This paper proposes a detection method and system that can achieve on-line monitoring of multiple shaft insulation parameters, including parameters such as resistance, capacitance, oil film thickness, shaft voltage, and dielectric constant.

[0003] In previous bearing insulation monitoring, generally an excitation source was connected from the insulation interface or insulation detection tap, and its equivalent impedance was a parallel impedance, and the measured value was the DC parallel resistance value, which could not truly reflect the actual working series impedance. For a single-layer insulation pad bearing structure, due to the dynamic variability of the oil film impedance, it is more difficult to reflect the true insulation state. Summary of the Invention

[0004] This application aims to at least solve one of the technical problems in the related art to some extent.

[0005] To this end, the first object of this application is to propose a method for multi-parameter monitoring of the insulation of a hydro-generator shaft. By introducing a co-excitation high-frequency current source from the grounding brush and simultaneously introducing the monitoring of high and low frequency components of the shaft voltage, on-line monitoring of multiple parameters of the bearing insulation can be achieved, including bearing oil film impedance, capacitance, resistance, and insulation impedance, capacitance, resistance, as well as capacitance ratio and shaft voltage.

[0006] The second object of this application is to propose a system for multi-parameter monitoring of the insulation of a hydro-generator shaft.

[0007] The third object of this application is to propose an electronic device.

[0008] The fourth object of this application is to propose a computer-readable storage medium.

[0009] The fifth object of this application is to propose a computer program product.

[0010] To achieve the above object, the first aspect embodiment of this application proposes a method for multi-parameter monitoring of the insulation of a hydro-generator shaft, including:

[0011] Adopting the co-excitation ratio method, introducing a high-frequency excitation current source through the grounding brush, loading a high-frequency voltage on the basis of the shaft voltage, respectively detecting the oil film voltage and the insulation backing plate voltage, calculating the voltage amplitude ratio, and analyzing the oil film capacitance and insulation capacitance based on the high-frequency signal;

[0012] Adopt the co-excitation polling method. The high-frequency excitation current path is switched sequentially by the poller, so that the high-frequency current flows through different impedance branches. The high-frequency and low-frequency voltage signals are separated by the frequency-selective filter to analyze the oil film impedance and insulation impedance.

[0013] Adopt the separate excitation method. Introduce a high-frequency excitation source separately from the bearing bush, and combine it with a frequency-selective filter or impedance converter to realize the independent measurement of the oil film impedance and insulation impedance, and calculate the oil film thickness and insulation parameters.

[0014] Optionally, in the co-excitation ratio method, the high-frequency excitation current source is loaded through the grounding brush lead, and a high-frequency micro-inductance is formed through the ferrite coil, so that the high-frequency excitation voltage is superimposed on the shaft voltage. The specific steps include:

[0015] Load a high-frequency excitation source on the grounding brush lead to make the ferrite coil form a high-frequency micro-inductance in the range of 10 to 100 μH to separate the high-frequency signal and the low-frequency shaft voltage signal. The shunt of the high-frequency excitation source I REF is I ref , and the formula is:

[0016]

[0017] In the formula, V oil is the oil film voltage, V isol is the insulation voltage, I ref is the high-frequency excitation current source, Z oil and Z isol are the oil film impedance and insulation impedance respectively;

[0018] Measure the oil film voltage on the bearing surface and the insulation pad voltage respectively. The oil film voltage on the bearing surface reflects the oil film impedance, and the insulation pad voltage reflects the insulation impedance;

[0019] Calculate the voltage amplitude ratio to obtain the ratio of the oil film capacitance to the insulation capacitance. The voltage amplitude ratio and the capacitance ratio satisfy the following relationship:

[0020]

[0021] In the formula, β is the voltage amplitude ratio, c oil is the oil film capacitance, c isol is the insulation capacitance;

[0022] Calculate the oil film capacitance and insulation capacitance based on the high-frequency voltage amplitude. The formula is:

[0023]

[0024] In the formula, ω H is the angular frequency of the high-frequency excitation source, and R is the reference impedance.

[0025] Optionally, in the co-excitation polling method, the high-frequency excitation current path is sequentially switched by a poller to separate high-frequency and low-frequency signals. The specific steps include:

[0026] Load the high-frequency excitation current onto different impedance branches sequentially through the poller, so that each impedance branch forms an independent electrical path;

[0027] Separate the high-frequency signal and the low-frequency signal through a frequency-selective filter. The high-frequency voltage signal is used to calculate the oil film impedance, and the low-frequency voltage signal is used to calculate the insulation impedance;

[0028] Calculate the current of each impedance branch. The current and voltage satisfy the following relationship, and the formula is:

[0029]

[0030] In the formula, IX 1H and IX 2H are high-frequency currents, IX 1L and IX 2L are low-frequency currents, VX 1H , VX 2H , VX 1L and VX 2L are the corresponding voltages;

[0031] Analyze the oil film resistance and the insulation resistance. Among them, the oil film admittance and the insulation admittance satisfy the following formula:

[0032]

[0033] Among them, G 1 and G 2 are the insulation admittance and the oil film admittance respectively, r isol and r oil are the insulation resistance and the oil film resistance respectively, ω L is the low-frequency angular frequency.

[0034] Optionally, in the separate excitation method, a high-frequency excitation current source is separately introduced from the bearing bush, and the oil film impedance and the insulation impedance are separated by combining a frequency-selective filter and an impedance converter. The specific steps include:

[0035] Load a high-frequency excitation current source on the insulation tap, and separate the oil film voltage signal through a frequency-selective filter;

[0036] Measure the oil film voltage and the high-frequency current signal, and calculate the oil film capacitance based on the high-frequency signal, which satisfies the following formula:

[0037]

[0038] Calculate the oil film thickness. The oil film thickness and the voltage amplitude ratio satisfy the following relationship:

[0039]

[0040] Among them, ε is the dielectric constant of the oil film medium, s is the area of the bearing bush, and β is the voltage amplitude ratio.

[0041] Optionally, in the co-excitation polling method, to eliminate the influence of the change in the dielectric constant of the lubricating oil, a reference capacitor is arranged in the oil sump for real-time detection of the dielectric constant of the oil film. The specific steps include:

[0042] Arrange a reference capacitor C in the oil sump ref , and the dielectric of the reference capacitor is the lubricating oil in the oil sump;

[0043] Real-time detect the dielectric constant of the lubricating oil, and eliminate the influence of the dielectric constant on the oil film thickness through the reference capacitor;

[0044] Calculate the oil film thickness based on the relationship between the high-frequency current and voltage, which satisfies the following formula:

[0045]

[0046] Among them, ω H is the high-frequency angular frequency, and ε is the dielectric constant measured in real time.

[0047] To achieve the above object, the second aspect embodiment of the present application proposes a bearing insulation multi-parameter monitoring system, including an upper guide bearing insulation monitoring unit, a lower guide bearing insulation monitoring unit, a thrust bearing insulation monitoring unit, a water guide bearing insulation monitoring unit and an upper computer system. Among them, each of the monitoring units includes:

[0048] A high-frequency excitation source, connected through a grounding brush, for loading a high-frequency voltage signal;

[0049] A sensor unit, arranged at the tile surface positions of the upper guide bearing, the lower guide bearing, the thrust bearing and the water guide bearing, for collecting oil film voltage and insulation impedance voltage signals;

[0050] A preconditioner, arranged near the oil sump or the insulation tap, for separating high-frequency and low-frequency signals and amplifying and conditioning the signals;

[0051] A digital signal processing unit, for collecting the conditioned signals through a multi-channel high-resolution A / D converter and calculating the shaft insulation parameters of the hydro-generator, including oil film capacitance, insulation capacitance, oil film thickness, oil film resistance and insulation resistance, by the method according to any one of claims 1-5;

[0052] A data transmission unit, for remotely transmitting the data of each monitoring unit to the upper computer system through an RS485 network;

[0053] The upper computer system is used to monitor, store, and analyze the received data in real time, and output the dynamic trends of the bearing insulation parameters and the oil film thickness.

[0054] Optionally, the digital signal processing unit further includes a spectrum analysis module, which is used to perform spectrum analysis on the monitoring signal and extract each harmonic component.

[0055] To achieve the above object, an embodiment of the third aspect of the present application provides an electronic device, including: a processor, and a memory communicatively connected to the processor;

[0056] The memory stores computer-executable instructions;

[0057] The processor executes the computer-executable instructions stored in the memory to implement the method described in any one of the first aspect.

[0058] To achieve the above object, an embodiment of the fourth aspect of the present application provides a computer-readable storage medium, in which computer-executable instructions are stored, and when the computer-executable instructions are executed by a processor, they are used to implement the method described in any one of the first aspect.

[0059] To achieve the above object, an embodiment of the fifth aspect of the present application provides a computer program product, and when the computer program is executed by a processor, it implements the method described in any one of the first aspect.

[0060] The technical solutions provided by the embodiments of the present application at least bring the following beneficial effects:

[0061] The present application provides a method and system for multi-parameter monitoring of the shaft insulation of a hydro-generator. By accessing a common excitation high-frequency current source from the grounding brush and introducing the monitoring of the high-frequency and low-frequency components of the shaft voltage, the method can realize the on-line multi-parameter monitoring of the bearing insulation. These parameters include the impedance, capacitance, and resistance of the bearing oil film, as well as the insulation impedance, capacitance, and resistance, etc., and also include the real-time monitoring of key signals such as the capacitance ratio and the shaft voltage. As a supplement, the method also supports introducing a high-frequency excitation source separately from the bearing bush to realize the independent monitoring of the bearing insulation.

[0062] The monitoring methods proposed in the present application include the common excitation ratio method, the common excitation polling method, and the separate excitation method. These methods can flexibly meet different bearing monitoring requirements, so as to provide an accurate bearing condition assessment. To implement this method, the present application also designs and implements an integrated monitoring system, which is composed of multiple subsystems, including the upper guide bearing insulation monitoring unit, the lower guide bearing insulation monitoring unit, the thrust bearing insulation monitoring unit, and the water guide bearing insulation monitoring unit, etc. Each subsystem shares data through the RS485 network and can transmit the data to the upper computer system for real-time monitoring, analysis, and fault warning.

[0063] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description of embodiments in conjunction with the accompanying drawings, in which:

[0065] Figure 1 Schematic diagram of the dynamic-side bearing parameter detection model provided by the embodiment of the present application;

[0066] Figure 2 Schematic diagram of the bearing insulation parameter detection preamplifier provided by the embodiment of the present application;

[0067] Figure 3 Schematic diagram of the static-side bearing insulation parameter detection preamplifier provided by the embodiment of the present application;

[0068] Figure 4 Schematic diagram of the digital signal processing unit provided by the embodiment of the present application;

[0069] Figure 5 Schematic diagram of the connection between the host computer system and each monitoring unit provided by the embodiment of the present application;

[0070] Figure 6 Flowchart of a method for multi-parameter monitoring of the shaft insulation of a hydro-generator provided by the embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0071] Embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the present application and should not be construed as limiting the present application.

[0072] In view of the problems existing in the prior art, the embodiment of the present application provides a method for multi-parameter monitoring of the shaft insulation of a hydro-generator. By connecting a common excitation high-frequency current source from the grounding brush and introducing the monitoring of the high-frequency and low-frequency components of the shaft voltage, on-line monitoring of multi-parameters of the bearing insulation can be realized, including the bearing oil film impedance, capacitance, resistance, and insulation impedance, capacitance, resistance, as well as the capacitance ratio and shaft voltage. As a supplement, it is also feasible to introduce a high-frequency excitation source separately from the bearing bush.

[0073] Figure 6 Schematic diagram of the flow of a method for multi-parameter monitoring of the shaft insulation of a hydro-generator provided by the embodiment of the present application. As Figure 1As shown, the method includes the following steps:

[0074] Step 101: Adopt the co-excitation ratio method. Introduce a high-frequency excitation current source through a grounding brush, load a high-frequency voltage on the basis of the shaft voltage, detect the oil film voltage and the insulating pad voltage respectively, calculate the voltage amplitude ratio, and analyze the oil film capacitance and the insulation capacitance based on the high-frequency signal.

[0075] Step 102: Adopt the co-excitation polling method. Sequentially switch the high-frequency excitation current path through a poller, enable the high-frequency current to flow through different impedance branches, separate the high-frequency and low-frequency voltage signals through a frequency-selective filter, and analyze the oil film impedance and the insulation impedance.

[0076] Step 103: Adopt the separate excitation method. Independently introduce a high-frequency excitation source from the bearing bush, combine with a frequency-selective filter or an impedance converter to achieve independent measurement of the oil film impedance and the insulation impedance, and calculate the oil film thickness and the insulation parameters.

[0077] In the embodiments of the present application, the physical models for detecting the oil film impedance of each bearing bush on the dynamic and static sides are as Figure 1 、 Figure 2 shown. The online monitoring method of the present application relies on the series relationship between the bearing oil film and the insulating pad capacitance. During the monitoring process, the grounding brush lead wire bypasses the ferrite to form a high-frequency inductor L1. The inductance value is 10 - 100 uH, and the ferrite material has the characteristic of extremely low impedance at low frequencies, thus ensuring that its static electricity discharge performance is not affected. A high-frequency excitation current source is loaded on the grounding brush lead wire to form a high-frequency shaft voltage VSH-H. Through this setting, the capacitive circuit of the bearing bush oil film and the insulating pad can be effectively driven, and then the online monitoring of multiple parameters can be realized.

[0078] It should be noted that the oil film capacitance of the tile surface and the insulating pad capacitance of each bearing bush insulation circuit are a series branch of the total parallel circuit. The oil film capacitance When the tile area s remains unchanged, c oil is proportional to the dielectric constant and inversely proportional to the oil film thickness d, while c isol mainly depends on the dielectric constant of the material of the insulating pad. The total current of the high-frequency excitation source is shunted into the currents of each bearing impedance branch. The magnitude of the branch current is uncertain, but in actual work, without an external excitation, the currents of each impedance component in a branch are equal.

[0079] In the co-excitation ratio method proposed in the embodiments of the present application, based on the series relationship between the oil film impedance of the tile surface and the insulation impedance of the insulating pad, by separately measuring the oil film voltage of the tile surface and the insulating pad voltage, the voltage amplitude ratio β can be calculated, and then the ratio of the oil film capacitance to the insulation capacitance can be obtained.

[0080] In this method, the high-frequency excitation current source is loaded through the grounded brush lead and forms a high-frequency micro-inductance through the ferrite coil, so that the high-frequency excitation voltage is superimposed on the shaft voltage to ensure that the high-frequency signal can be effectively separated from the low-frequency shaft voltage signal. The specific steps are as follows:

[0081] First, load the high-frequency excitation source through the grounded brush lead to make the ferrite coil form a high-frequency micro-inductance in the range of 10 to 100 μH. This inductance separates the high-frequency signal from the low-frequency shaft voltage signal to ensure that the high-frequency signal does not interfere with the low-frequency signal. The total current I of the high-frequency excitation source REF is shunted to different impedance branches, and the oil film voltage V oil and the insulation voltage V isol are related as follows:

[0082]

[0083] In the formula, V oil is the oil film voltage, V isol is the insulation voltage, I ref is the high-frequency excitation current source, and Z oil and Z isol are the oil film impedance and the insulation impedance respectively.

[0084] Then, measure the oil film voltage on the bearing surface and the insulation pad voltage respectively. Among them, the oil film voltage on the bearing surface reflects the oil film impedance, and the insulation pad voltage reflects the insulation impedance. Thus, according to the measured voltage amplitude ratio β, the ratio of the oil film capacitance to the insulation capacitance can be obtained. The formula is:

[0085]

[0086] In the formula, c oil is the oil film capacitance, and c isol is the insulation capacitance. By calculating the voltage amplitude ratio β, the relationship between the oil film capacitance and the insulation capacitance can be further deduced.

[0087] Moreover, based on the high-frequency voltage amplitude VSH and the current IX, the oil film capacitance and the insulation capacitance can be calculated. First, calculate their respective capacitance values through the amplitude of the high-frequency current. The formula is as follows:

[0088] For the insulation capacitance c isol , its calculation formula is:

[0089]

[0090] Similarly, for the oil film capacitance c oil , its calculation formula is:

[0091]

[0092] Where ω H is the angular frequency of the high-frequency excitation source, and R is the reference impedance.

[0093] Through the co-excitation ratio method, a high-frequency voltage signal can be superimposed on the shaft voltage using a high-frequency excitation source, and by measuring the oil film voltage on the bearing surface and the voltage of the insulating backing plate, the ratio of the voltage amplitudes can be calculated to further deduce the ratio of the oil film capacitance to the insulation capacitance. This method can accurately monitor the states of the oil film and insulation through current shunting and effective separation of high-frequency signals, providing effective support for bearing health assessment and fault warning.

[0094] For the co-excitation polling method proposed in the embodiments of the present application, as Figure 2 shown, the current intercepting function of the poller is used to make the high-frequency current introduced from the grounding brush flow through different impedance branches alternately. The measured voltage VX contains components of high-frequency and low-frequency shaft voltages. By decomposing the measured voltage into high-frequency voltage VX H and low-frequency voltage VX L , the impedance current can be calculated, and the expression is:

[0095]

[0096] Where IX 1H and IX 2H are high-frequency currents, IX 1L and IX 2L are low-frequency currents, and VX 1H , VX 2H , VX 1L and VX 2L are the corresponding voltages.

[0097] For the double-layer insulation pad structure with an insulating tap on the moving side, if the insulating tap is led out using a shaft-top slip ring and a carbon brush, the insulation impedance c isol and the oil film impedance c oil cannot be separated. For the single-layer insulation pad on the static side, it is necessary to ensure that the oil film does not independently bear the low-frequency shaft voltage during monitoring. Therefore, frequency-selective filters (1) and (2) are specially added before the poller, and then through the impedance converter built into the poller, the oil film only bears a safe small-amplitude high-frequency voltage and does not bear the low-frequency shaft voltage. This method ensures the accurate monitoring of the oil film impedance and protects the oil film from the influence of low-frequency voltages.

[0098] For multi-bearing monitoring, the poller can work in a synchronous mode, loading high-frequency excitation currents into different impedance branches one by one, so that each impedance branch forms an independent electrical loop. The high-frequency and low-frequency signals are separated through the frequency-selective filter. The high-frequency voltage signal is used to calculate the oil film impedance, and the low-frequency voltage signal is used to calculate the insulation impedance.

[0099] On this basis, the oil film resistance and insulation resistance can be analyzed by the following formulas

[0100]

[0101] In the formula, G 1 is the insulation admittance, and r isol is the insulation resistance, and its calculation formula is:

[0102]

[0103] Similarly, the calculation formulas for the oil film admittance G 2 and the oil film resistance r oil are:

[0104]

[0105] In these formulas, G 1 and G 2 are the insulation admittance and the oil film admittance respectively, r isol and r oil are the insulation resistance and the oil film resistance respectively, and ω L is the low-frequency angular frequency.

[0106] Through the co-excitation polling method, the present application effectively realizes the independent monitoring of different bearing impedance branches, ensuring that the impedances of the oil film and the insulation pad can be accurately separated and calculated. By using a frequency-selective filter and an impedance converter, the interference of low-frequency signals on the oil film impedance is avoided, ensuring the accuracy and reliability of the oil film monitoring. At the same time, by analyzing and calculating the resistance values of the oil film and the insulation, the monitoring accuracy of the bearing insulation state is further improved, which has important application value.

[0107] In addition, in the co-excitation polling method, in order to eliminate the influence of the change in the dielectric constant of the lubricating oil on the measurement of the oil film thickness, the present application additionally introduces the design of a reference capacitor. By arranging a reference capacitor in the oil tank, the dielectric constant of the oil film can be monitored in real time and its interference on the measurement of the oil film thickness can be eliminated. The following are the specific implementation steps:

[0108] First, arrange a reference capacitor C ref in the oil tank. The dielectric of the reference capacitor is the lubricating oil in the oil tank. Since the dielectric constant ε of the lubricating oil changes with time, the arrangement of the reference capacitor can be used to detect the change in the dielectric constant of the lubricating oil in real time.

[0109] Then, by real-time monitoring the capacitance value of the reference capacitor, the change in the dielectric constant of the lubricating oil can be indirectly deduced, thereby eliminating the influence of the change in the dielectric constant on the measurement of the oil film thickness. Using the change in the reference capacitor, the system can adjust the calculation result of the oil film thickness in a timely manner according to the dielectric constant of the lubricating oil in the oil sump. After eliminating the influence of the change in the dielectric constant of the lubricating oil, the oil film thickness can be accurately calculated. Based on the relationship between the high-frequency current and voltage, the oil film capacitance c oil and the oil film thickness d oil satisfy the following formula:

[0110]

[0111] where ω H is the high-frequency angular frequency, ε is the dielectric constant measured in real time, I oilH and V oilH are the high-frequency current and voltage signals of the oil film respectively.

[0112] Through the dielectric constant ε measured in real time, the thickness d oil of the oil film can be further calculated, and its calculation formula is:

[0113]

[0114] where ε is the dielectric constant of the lubricating oil in the oil sump, V oilH and V XH are the high-frequency voltage signals of the oil film and the reference capacitor respectively, and R is the reference impedance.

[0115] By arranging a reference capacitor in the oil sump and real-time monitoring the dielectric constant of the lubricating oil, the present invention can effectively eliminate the influence of the change in the dielectric constant of the lubricating oil on the measurement of the oil film thickness. Using the relationship between the high-frequency current and voltage to calculate the oil film capacitance and the oil film thickness realizes the precise monitoring and dynamic adjustment of the oil film state. This method significantly improves the accuracy of bearing monitoring, especially in the case of large fluctuations in the dielectric constant of the lubricating oil, ensuring the reliable measurement of the oil film thickness.

[0116] In the separate excitation method proposed in the embodiment of the present application, for the multi-parameter monitoring of bearing insulation, by separately introducing a high-frequency excitation source from the bearing bush, it is possible to realize the analysis and monitoring of the power frequency shaft voltage without relying on the shaft voltage brush. The specific steps are as follows:

[0117] First, as Figure 3As shown, a high-frequency excitation source IGH(29-1) is added to the insulated tap. For the double-layer insulating pad structure with an insulated tap on the static side, by using the high-frequency excitation source and combining with a frequency-selective filter (or impedance converter), the impedance of each bearing bush can be divided into oil film impedance and insulating pad impedance, and the thickness of the oil film can be measured more accurately. In the single-layer insulating pad structure, if an additional insulating pad is added, a high-frequency excitation source is added to the insulated tap, and then the oil film impedance and insulating pad impedance are separated through the impedance converter (21), the same effect can be achieved. If the oil film resistance needs to be measured accurately, an excitation source IGL(29-2) with a relatively low frequency (such as 1 kHz) can be introduced, and the oil film resistance can be obtained by combining with the polling method for analysis.

[0118] Through the above method, the voltage signal of the oil film and the insulating voltage signal can be separated by high-frequency current and voltage signals. By using a frequency-selective filter, the voltage signal of the oil film can be effectively separated. The specific steps of the separate excitation method include:

[0119] First, a high-frequency excitation current source is loaded on the insulated tap, and the voltage signal of the oil film is separated through a frequency-selective filter.

[0120] Then, the voltage of the oil film and the high-frequency current signal are measured, and the oil film capacitance is calculated based on the high-frequency signal. The calculation formula is:

[0121]

[0122] where ω H is the angular frequency of the high-frequency excitation source, I oilH and V oilH are the high-frequency current and voltage signals of the oil film respectively.

[0123] In addition, the oil film thickness d oil is calculated through the voltage amplitude ratio β and the capacitance c isol . The relationship between the oil film thickness and the voltage amplitude ratio is as follows:

[0124]

[0125] where ε is the dielectric constant of the oil film medium, s is the area of the bearing bush, and β is the voltage amplitude ratio.

[0126] Through this formula, the thickness of the oil film can be calculated.

[0127] Through the separate excitation method, a high-frequency excitation source can be independently introduced without relying on the shaft voltage brush, and the impedance of the oil film and the insulating pad can be separated by combining with a frequency-selective filter and an impedance converter. By accurately measuring the oil film voltage and the insulating voltage, key parameters such as the oil film capacitance and the oil film thickness can be effectively calculated. This method can not only achieve multi-parameter monitoring but also improve the monitoring accuracy, providing an important basis for the health assessment and fault warning of the bearing.

[0128] To implement the above embodiments, the present application also proposes a bearing insulation multi-parameter monitoring system. The bearing insulation multi-parameter monitoring system proposed by the present application is as Figure 5 shown. The system includes multiple monitoring units and a host computer system. The monitoring units are respectively used to monitor the bearing insulation status of different parts in the shafting. The host computer system is used to monitor, store, and analyze the received data in real time, and output the dynamic trends of bearing insulation parameters and oil film thickness. Specifically, the system includes an upper guide bearing insulation monitoring unit, a lower guide bearing insulation monitoring unit, a thrust bearing insulation monitoring unit, a water guide bearing insulation monitoring unit, and a host computer system. Each monitoring unit realizes data sharing through an RS485 network and transmits the data to the host computer system for processing and analysis.

[0129] Specifically, each monitoring unit includes:

[0130] High-frequency excitation source: Introduced through a grounding brush, used to load high-frequency voltage signals. This excitation source superimposes high-frequency signals on the shaft voltage to ensure effective separation of high-frequency and low-frequency signals.

[0131] Sensor unit: Arranged at the tile surface positions of the upper guide bearing, lower guide bearing, thrust bearing, and water guide bearing in the shafting, used to collect oil film voltage and insulation impedance voltage signals.

[0132] Preconditioner: Arranged near the oil sump or insulation tap, responsible for signal preprocessing. Its main function is to separate high-frequency and low-frequency signals, and amplify and condition the signals. The preconditioner includes components such as a high-pass frequency selection filter, a low-pass frequency selection filter, a poller, an amplifier, a differentiator, and a control switch.

[0133] Digital signal processing unit: Used to collect the conditioned signals through a multi-channel high-resolution A / D converter and calculate multiple bearing insulation parameters, including oil film capacitance, insulation capacitance, oil film thickness, oil film resistance, and insulation resistance. This unit also includes a spectrum analysis module that can perform spectrum analysis on the monitoring signals, extract each harmonic component, and assist the system in analysis and fault warning.

[0134] Data transmission unit: Remotely transmits the data of each monitoring unit to the host computer system through an RS485 network.

[0135] It should be noted that in the bearing monitoring system of this application, the selection of measurement points is very crucial. The measurement points should be selected at one or more bearing bush positions of the upper guide bearing and thrust bearing of the shafting. Selecting these positions as measurement points can effectively capture the electrical characteristics of each part of the bearing, accurately monitor the state of the oil film and insulation pad, and calculate the insulation capacitance of each part of the bearing according to the factory design and actual specific dimensions. This parameter is crucial for evaluating the performance of the insulation backing plate.

[0136] In addition, referring to Figure 2 , the preconditioner 1 is composed of components such as a high-pass frequency-selective filter (1), a low-pass frequency-selective filter (2), a poller (3), high-pass frequency-selective amplifiers (4, 6), low-pass frequency-selective amplifiers (5, 7), a differentiator (8), a control switch SW (9), etc. The preconditioner introduces the shaft voltage VSH and the ground point GRN from the shaft brush, and introduces the insulation impedance junction point P from the bearing bush base or insulation tap: The impedance insulation voltage VX is detected in a polling manner H , VX L , the impedance insulation current IX H , IX L . The preconditioner 2 is composed of components such as a preamplifier differentiator (10, 15), frequency-selective filters (11, 16), differentiators (12, 17), frequency-selective amplifiers (13, 18), demodulators (14, 19), and a divider (15), and outputs the capacitance ratio β.

[0137] Through the combination of these functional modules, the preconditioner can achieve multi-level processing of signals, including the separation of high-frequency and low-frequency signals, the amplification and conditioning of signals, and finally ensure that the signal quality meets the requirements, facilitating the subsequent analysis and calculation by the digital signal processing unit. And the preconditioner guides the high-frequency and low-frequency signals to different impedance branches in turn through the poller. Specifically, the shaft voltage introduced from the shaft brush and the signal on the ground point, as well as the insulation impedance junction point introduced from the bearing bush base or insulation tap, after polling, will respectively detect the impedance insulation voltage and impedance current. These signals, after being processed, will be transmitted to the digital signal processing unit for further analysis.

[0138] In addition, as Figure 4 shown, the detected signals (VX H , VX L , VSH H , VSH L ) 1～N , (β 1 , β 2 , …β N ) of the bearing position are led out to the digital signal processing unit 3 through a shielded cable, and the analog-to-digital conversion is completed through a multi-channel high-resolution A / D. The CPU calculates the insulation impedance z and capacitance (c isol , coil ) Resistance (r isol , r oil ), oil film thickness d oil of dynamic and static data, as well as their maximum values, minimum values, peak-to-peak values, and mean values; it can perform spectral analysis on signals such as shaft voltage and oil film thickness, and extract each harmonic component. The digital signal processing unit can form a local RS485 network to meet the requirements of multi-parameter and multi-channel online monitoring of bearings.

[0139] Through high-resolution A / D conversion and a digital signal processing unit, this system can accurately monitor and calculate multiple key parameters of bearings, such as insulation impedance, capacitance, resistance, and oil film thickness. At the same time, with the help of spectral analysis and harmonic component extraction, the shaft voltage signal can be further analyzed, providing a scientific basis for the health assessment and fault warning of bearings. With the support of the RS485 network, the system can achieve data sharing and remote transmission of multiple monitoring channels, ensuring the real-time and reliability of bearing monitoring.

[0140] To implement the above embodiments, this application also proposes an electronic device, including: a processor, and a memory communicatively connected to the processor; the memory stores computer-executable instructions; the processor executes the computer-executable instructions stored in the memory to implement the method provided in the foregoing embodiments.

[0141] To implement the above embodiments, this application also proposes a computer-readable storage medium storing computer-executable instructions, and the computer-executable instructions are used to implement the method provided in the foregoing embodiments when executed by a processor.

[0142] To implement the above embodiments, this application also proposes a computer program product including a computer program, and the computer program implements the method provided in the foregoing embodiments when executed by a processor.

[0143] The collection, storage, use, processing, transmission, provision, and disclosure of user personal information involved in this application all comply with the provisions of relevant laws and regulations and do not violate public order and good customs.

[0144] It should be noted that personal information from users should be collected for legal and reasonable purposes and should not be shared or sold outside of these legal uses. In addition, such collection / sharing should be carried out after obtaining the informed consent of the user, including but not limited to notifying the user to read the user agreement / user notice and sign an agreement / authorization including authorizing relevant user information before the user uses the function. In addition, any necessary steps should be taken to protect and safeguard access to such personal information data and ensure that others with access to personal information data comply with their privacy policies and procedures.

[0145] This application is expected to provide an implementation scheme for users to selectively block the use or access of personal information data. That is, the present disclosure is expected to provide hardware and / or software to prevent or block access to such personal information data. Once the personal information data is no longer needed, the risk can be minimized by restricting data collection and deleting the data. In addition, when applicable, personal identifiers are removed from such personal information to protect the privacy of users.

[0146] In the description of the foregoing embodiments, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0147] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present application, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0148] Any process or method description shown in the flowchart or described in other ways herein can be understood as representing a module, segment, or part of code including one or more executable instructions for implementing a customized logic function or process, and the scope of the preferred implementation of the present application includes additional implementations, where the functions can be executed in a substantially simultaneous manner or in the reverse order according to the functions involved, rather than in the order shown or discussed, which should be understood by those skilled in the art to which the embodiments of the present application belong.

[0149] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a definite list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, a system including a processor, or other systems that can fetch and execute instructions from the instruction execution system, apparatus, or device. As used in this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by or in connection with the instruction execution system, apparatus, or device. More specific examples (non-exhaustive list) of the computer-readable medium include the following: an electrical connection portion having one or more wirings (electronic device), a portable computer diskette (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium can even be paper or other suitable medium on which the program can be printed, as the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpretation, or otherwise processing as appropriate, and then storing it in a computer memory.

[0150] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or a combination of the following techniques well known in the art can be used: discrete logic circuits having logic gate circuits for implementing logical functions on data signals, application specific integrated circuits having appropriate combinational logic gate circuits, programmable gate arrays (PGAs), field programmable gate arrays (FPGAs), etc.

[0151] Those of ordinary skill in the art of the present technology can understand that all or part of the steps carried by the method of the above-described embodiments can be completed by a program instructing relevant hardware, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiments.

[0152] In addition, each functional unit in various embodiments of the present application may be integrated into a processing module, may exist physically alone for each unit, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. When the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0153] The above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disc, etc. Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those of ordinary skill in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present application.

[0154] It should be understood that various forms of the processes shown above may be used, steps may be reordered, added or deleted. For example, the steps described in the present application may be executed in parallel, sequentially or in a different order, as long as the desired results of the technical solution of the present application can be achieved, and no limitation is imposed herein.

[0155] The above specific implementation manners do not constitute a limitation on the protection scope of the present application. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A multi-parameter monitoring method for shaft insulation of a hydro-generator, characterized in that: The following steps are involved: The common excitation ratio method is adopted to introduce a high-frequency excitation current source through the grounding brush, and a high-frequency voltage is loaded on the basis of the shaft voltage. The oil film voltage and the insulating pad voltage are detected respectively, and the voltage amplitude ratio is calculated. The oil film capacitance and the insulating capacitance are analyzed based on the high-frequency signal. The common excitation polling method is adopted to switch the high-frequency excitation current path in sequence through the polling device, so that the high-frequency current flows through different impedance branches, and the high-frequency and low-frequency voltage signals are separated by the frequency-selective filter to analyze the oil film impedance and insulation impedance. The separate excitation method is adopted to introduce a high-frequency excitation source from the bearing alone, combined with a frequency-selective filter or impedance converter, to achieve independent measurement of oil film impedance and insulation impedance, and calculate the oil film thickness and insulation parameters.

2. The bearing insulation multi-parameter monitoring method according to claim 1 is characterized in that: In the common excitation ratio method, the high-frequency excitation current source is loaded through the grounding brush lead, and a high-frequency micro-inductor is formed through the ferrite coil, so that the high-frequency excitation voltage is superimposed on the shaft voltage. The specific steps include: A high-frequency excitation source is loaded on the ground brush lead to form a high-frequency micro-inductance in the range of 10 to 100 μH in the ferrite coil to separate the high-frequency signal from the low-frequency shaft voltage signal. REF The flow is I ref , the formula is: Where V oil is the oil film voltage, V isol is the insulation voltage, I ref is the high frequency excitation current source, Z oil and Z isol They are oil film resistance and insulation resistance respectively; The oil film voltage on the tile surface and the insulating pad voltage are measured respectively, wherein the oil film voltage on the tile surface reflects the oil film impedance and the insulating pad voltage reflects the insulation impedance; The voltage amplitude ratio is calculated to obtain the ratio of the oil film capacitance to the insulation capacitance. The voltage amplitude ratio and the capacitance ratio satisfy the following relationship: Where β is the voltage amplitude ratio, c oil is the oil film capacitance, c isol is the insulation capacitance; The oil film capacitance and insulation capacitance are calculated based on the high-frequency voltage amplitude. The formula is: In the formula, ω H is the angular frequency of the high frequency excitation source, and R is the reference impedance.

3. The method according to claim 2, characterized in that In the co-excitation polling method, the high-frequency excitation current path is switched in sequence by a polling device to separate the high-frequency and low-frequency signals. The specific steps include: The high-frequency excitation current is sequentially loaded to different impedance branches through the polling device, so that each impedance branch forms an independent electrical path; A high-frequency signal and a low-frequency signal are separated by a frequency-selective filter, wherein the high-frequency voltage signal is used to calculate the oil film impedance, and the low-frequency voltage signal is used to calculate the insulation impedance; The current of each impedance branch is calculated, and the current and voltage satisfy the following relationship, which is as follows: Where, IX 1H and IX 2H is the high frequency current, IX 1L and IX 2L is the low frequency current, VX 1H 、VX 2H 、VX 1L With VX 2L is the corresponding voltage; Analyze the oil film resistance and insulation resistance, where the oil film admittance and insulation admittance satisfy the following formula: Among them, G1 and G2 are insulation admittance and oil film admittance respectively, r isol and r oil are insulation resistance and oil film resistance, ω L is the low frequency corner frequency.

4. The method according to claim 3, characterized in that: In the separate excitation method, a high-frequency excitation current source is introduced from the bearing bush separately, and a frequency-selective filter and an impedance converter are combined to separate the oil film impedance and the insulation impedance. The specific steps include: A high-frequency excitation current source is loaded on the insulation tap, and the oil film voltage signal is separated by a frequency-selective filter; The oil film voltage and high-frequency current signals are measured, and the oil film capacitance is calculated based on the high-frequency signals to meet the following formula: Calculate the oil film thickness. The oil film thickness and voltage amplitude ratio satisfy the following relationship: Among them, ε is the dielectric constant of the oil film medium, s is the bearing area, and β is the voltage amplitude ratio.

5. The method according to claim 4, characterized in that In the co-excitation polling method, in order to eliminate the influence of the change in the dielectric constant of the lubricating oil, a reference capacitor is arranged in the oil tank to detect the dielectric constant of the oil film in real time. The specific steps include: Place reference capacitor C in the oil tank ref , the medium of the reference capacitor is the lubricating oil in the oil tank; Real-time detection of the dielectric constant of the lubricating oil, and elimination of the influence of the dielectric constant on the oil film thickness by using a reference capacitor; The oil film thickness is calculated based on the relationship between high-frequency current and voltage, which satisfies the following formula: Among them, ω H is the high frequency angular frequency, and ε is the dielectric constant measured in real time.

6. A bearing insulation multi-parameter monitoring system, characterized in that: It includes an upper guide bearing insulation monitoring unit, a lower guide bearing insulation monitoring unit, a thrust bearing insulation monitoring unit, a water guide bearing insulation monitoring unit and a host computer system, wherein each of the monitoring units includes: A high-frequency excitation source is connected through a grounding brush and is used to load a high-frequency voltage signal; The sensor unit is arranged at the pad surface of the upper guide bearing, the lower guide bearing, the thrust bearing and the water guide bearing, and is used to collect oil film voltage and insulation impedance voltage signals; The pre-conditioner is arranged near the oil tank or the insulating tap, and is used to separate the high-frequency and low-frequency signals and amplify and condition the signals; A digital signal processing unit, used for collecting conditioned signals through multiple high-resolution A / D converters, and calculating the insulation parameters of the turbine generator shaft, including oil film capacitance, insulation capacitance, oil film thickness, oil film resistance and insulation resistance, by the method described in any one of claims 1 to 5; Data transmission unit, used to transmit the data of each monitoring unit to the upper computer system through RS485 network; The upper computer system is used to monitor, store and analyze the received data in real time, and output the dynamic trend of the bearing insulation parameters and oil film thickness.

7. The system according to claim 6, characterized in that The digital signal processing unit also includes a spectrum analysis module, which is used to perform spectrum analysis on the monitoring signal and extract various harmonic components.

8. An electronic device, characterized in that: include: A processor, and a memory communicatively connected to the processor; The memory stores computer-executable instructions; The processor executes the computer-executable instructions stored in the memory to implement the method according to any one of claims 1 to 5.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer-executable instructions, which are used to implement the method according to any one of claims 1 to 5 when executed by a processor.

10. A computer program product, characterized in that The invention comprises a computer program, which implements the method according to any one of claims 1 to 5 when being executed by a processor.

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