Method and device for on-line monitoring of dielectric loss and capacitance of high voltage bushing

Abstract

The application discloses an on-line monitoring method and device for dielectric loss and capacitance of a high-voltage bushing, wherein the high-voltage bushing is arranged on a transformer, a leakage current sensor is arranged on the inner wall of the end screen of the high-voltage bushing, the leakage current sensor collects the leakage current of the high-voltage bushing during operation, the leakage current sequentially passes through a current processing assembly and a microprocessor, a voltage transformer measures the operating voltage of the high-voltage bushing, the operating voltage sequentially passes through a voltage processing assembly and the microprocessor, the microprocessor converts the operating voltage and the leakage current into the sum of the fundamental component and the harmonic component, and transmits the sum to an industrial computer to calculate the dielectric loss value and the capacitance, a temperature sensor measures the operating temperature of the high-voltage bushing and transmits the operating temperature to the industrial computer, the industrial computer obtains the converted dielectric loss value according to the dielectric loss value and the operating temperature and displays the converted dielectric loss value, and the industrial computer is provided with a threshold value, and when the capacitance or the converted dielectric loss value exceeds the threshold value, the industrial computer sends an alarm signal.

Description

Technical Field

[0001] The present invention relates to the technical field of power equipment measurement, and in particular to an online monitoring method and device for dielectric loss and capacitance of a high-voltage bushing. Background Art

[0002] Transformers, current transformers and other equipment often use oil-paper insulated or rubber-paper insulated high-voltage bushings. Dielectric loss and capacitance are key parameters to characterize the insulation status of high-voltage bushings. By measuring the dielectric loss and capacitance of high-voltage bushings, possible insulation problems of the high-voltage bushings can be discovered.

[0003] Traditionally, the dielectric loss value and capacitance of high-voltage bushings are measured during power outages. This method cannot detect changes in the dielectric loss value and capacitance of high-voltage bushings in real time. By using online monitoring devices to monitor the dielectric loss value and capacitance of high-voltage bushings in real time, early defects and faults of high-voltage bushings can be identified and diagnosed, thus preventing the development of defects and the occurrence of faults.

[0004] Currently, online monitoring devices for high-voltage bushing dielectric loss and capacitance often use direct measurement methods. This not only makes it difficult to extract tiny signals in the complex electromagnetic environment of substations, but also suffers from low measurement accuracy. Furthermore, traditional online monitoring devices for high-voltage bushing dielectric loss do not consider the impact of measurement temperature and do not perform a unified temperature conversion. Consequently, measurement results lack a temperature basis, leading to inaccurate results. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that when traditional online monitoring devices measure the dielectric loss value of high-voltage bushings, they do not consider the influence of the measurement temperature on the dielectric loss value and do not perform a unified temperature conversion, resulting in inaccurate measurement results. The purpose of the present invention is to provide an online monitoring method and device for the dielectric loss and capacitance of high-voltage bushings to solve the problem of inaccurate measurement results of the dielectric loss value and capacitance of high-voltage bushings in substations.

[0006] The present invention is achieved through the following technical solutions:

[0007] An online monitoring method for dielectric loss and capacitance of a high-voltage bushing, the method comprising the following steps:

[0008] S1: A leakage current sensor is provided on the inner wall of the high-voltage bushing end screen, and the leakage current sensor collects the leakage current of the high-voltage bushing during operation;

[0009] S2: The leakage current passes through the current processing component and the microprocessor in sequence;

[0010] S3: The voltage transformer measures the operating voltage of the high-voltage bushing;

[0011] S4: The operating voltage passes through the voltage processing component and the microprocessor in sequence;

[0012] S5: The microprocessor converts the operating voltage into the sum of the fundamental component and each harmonic component of the voltage signal, converts the leakage current into the sum of the fundamental component and each harmonic component of the current signal, and transmits to the industrial computer;

[0013] S6: The industrial computer calculates the dielectric loss value and the capacitance according to the sum of the fundamental component and each harmonic component of the leakage current and the operating voltage;

[0014] S7: The temperature sensor measures the operating temperature of the high-voltage bushing and transmits to the industrial computer;

[0015] S8: The industrial computer obtains the converted dielectric loss value according to the dielectric loss value and the operating temperature;

[0016] S9: The industrial computer is provided with a threshold value, and when the capacitance or the converted dielectric loss value exceeds the threshold value, the industrial computer sends an alarm signal.

[0017] In the scheme, the high-voltage bushing is located on a device such as a transformer or a current transformer, a leakage current sensor is arranged on the inner wall of the end screen of the high-voltage bushing, and the leakage current sensor collects the leakage current when the high-voltage bushing operates; the leakage current sensor is connected with a current processing component, the current processing component is used for preprocessing the current signal, the current processing component is connected with a microprocessor, the microprocessor converts the leakage current into the sum of the fundamental component and each harmonic component, and transmits to the industrial computer; a voltage transformer measures the operating voltage of the high-voltage bushing, the voltage transformer is connected with a voltage processing component, the voltage processing component is used for preprocessing the voltage signal, the voltage processing component is connected with the microprocessor, the microprocessor converts the operating voltage of the high-voltage bushing into the sum of the fundamental component and each harmonic component, and transmits to the industrial computer; the industrial computer calculates the dielectric loss value and the capacitance of the high-voltage bushing according to the sum of the fundamental component and each harmonic component of the leakage current and the operating voltage; the temperature sensor measures the operating temperature of the high-voltage bushing and transmits to the industrial computer, the temperature sensor is used to fully consider the influence of the measurement temperature, and the temperature is uniformly converted, the industrial computer obtains the converted dielectric loss value according to the dielectric loss value and the operating temperature, the industrial computer stores and displays the calculated dielectric loss value, and the problem that the traditional online monitoring device does not consider the influence of the measurement temperature on the dielectric loss value and does not uniformly convert the temperature when measuring the dielectric loss value of the high-voltage bushing, resulting in inaccurate measurement results is solved.

[0018] The industrial computer is provided with a threshold value, the industrial computer compares the threshold value with the capacitance and the converted dielectric loss value, and when the capacitance or the converted dielectric loss value exceeds the threshold value, the industrial computer sends an alarm signal.

[0019] In some implementable schemes, the online monitoring method for the dielectric loss and capacitance of the high-voltage bushing, the step S2 comprises:

[0020] A1: The leakage current sensor is connected to a current processing component, which performs current amplification, filtering, square wave shaping, and analog-to-digital conversion on the leakage current in sequence;

[0021] A2: The current processing component is connected to a microprocessor, and the current processing component transmits the processed leakage current to the microprocessor.

[0022] In this solution, the current amplification process is used to protect the circuit; the filtering process and square wave shaping process are used to filter out clutter; and the analog-to-digital conversion process is used to convert the analog current signal into a digital signal.

[0023] In some feasible solutions, the online monitoring method for dielectric loss and capacitance of a high-voltage bushing, the above step S4 includes:

[0024] C1: The voltage transformer is connected to a voltage processing component, which performs voltage amplification, filtering, square wave shaping, and analog-to-digital conversion on the operating voltage in sequence;

[0025] C2: The voltage processing component is connected to the microprocessor, and the voltage processing component transmits the processed operating voltage to the microprocessor.

[0026] In this solution, the voltage amplification process is used to protect the circuit; the filtering process and square wave shaping process are used to filter out clutter; and the analog-to-digital conversion process is used to convert an analog voltage signal into a digital signal.

[0027] In some feasible solutions, the method for online monitoring of dielectric loss and capacitance of a high-voltage bushing, step S5 includes:

[0028] D1: The above-mentioned microprocessor performs discrete Fourier transform on the operating voltage, converts the voltage signal into the sum of the fundamental component and each harmonic component, and transmits it to the industrial computer;

[0029] D2: At the same time, the above-mentioned microprocessor performs discrete Fourier transform on the leakage current, converts the current signal into the sum of the fundamental component and each harmonic component, and transmits it to the industrial computer.

[0030] In some feasible solutions, in the method for online monitoring of dielectric loss and capacitance of a high-voltage bushing, the above-mentioned steps S1, S3 and S7 are performed simultaneously and at the same time;

[0031] When the leakage current sensor collects the leakage current of the high-voltage bushing, the voltage transformer collects the operating voltage of the high-voltage bushing, and the collection time and frequency of the leakage current sensor and the voltage transformer are consistent;

[0032] When the voltage transformer collects the operating voltage of the high-voltage bushing, the temperature sensor collects the operating temperature of the high-voltage bushing, and the collection time and frequency of the voltage transformer and the temperature sensor are consistent.

[0033] In this solution, when the leakage current sensor starts to collect the leakage current of the high-voltage bushing, the voltage transformer starts to collect the operating voltage of the high-voltage bushing, and the temperature sensor starts to collect the operating temperature of the high-voltage bushing. The working hours of the leakage current sensor, voltage transformer and temperature sensor are consistent, and the signals are collected synchronously, thereby improving work efficiency.

[0034] In some feasible solutions, the online monitoring method for dielectric loss and capacitance of a high-voltage bushing, the above step S9 includes:

[0035] The industrial computer is provided with an alarm threshold, and is connected to an alarm device. When the capacitance or the converted dielectric loss value exceeds the threshold, the industrial computer controls the alarm device to send out an alarm signal.

[0036] In this solution, the alarm device may be an LED flash light connected to the industrial computer, a built-in speaker in the industrial computer system, or other alarm devices.

[0037] In some feasible solutions, the online monitoring device for dielectric loss and capacitance of high-voltage bushing includes:

[0038] A leakage current sensor is arranged on the inner wall of the high-voltage bushing end screen;

[0039] a current processing component connected to the leakage current sensor;

[0040] a microprocessor connected to the current processing component;

[0041] A voltage transformer, which is used to measure the operating voltage of the high-voltage bushing;

[0042] A voltage processing component, wherein the voltage transformer is connected to the microprocessor via the voltage processing component;

[0043] A temperature sensor is used to measure the operating temperature of the high-voltage bushing;

[0044] The industrial computer is connected to the microprocessor and the temperature sensor respectively, and the industrial computer is provided with a threshold value. The industrial computer is used to calculate the capacitance and dielectric loss value of the high-voltage bushing according to the data transmitted by the microprocessor and the temperature sensor. If the capacitance and dielectric loss value exceed the threshold value, the industrial computer sends an alarm signal.

[0045] In this solution, the leakage current sensor measures the leakage current signal of the high-voltage bushing and transmits it to the current processing component. The current processing component pre-processes the leakage current signal and transmits it to the microprocessor. The microprocessor performs a discrete Fourier transform on the leakage current, converting the current signal into the sum of the fundamental component and each harmonic component, and transmits it to the industrial computer.

[0046] The voltage transformer measures the operating voltage of the high-voltage bushing and transmits it to the voltage processing component. The voltage processing component pre-processes the operating voltage signal and transmits it to the microprocessor. The microprocessor performs a discrete Fourier transform on the operating voltage, converting the voltage signal into the sum of the fundamental component and each harmonic component, and transmits it to the industrial computer.

[0047] The temperature sensor measures the operating temperature of the high-voltage bushing and transmits the data to the industrial computer. The industrial computer calculates the dielectric loss value and capacitance based on the leakage current and the sum of the fundamental component and each harmonic component of the operating voltage, and calculates the converted dielectric loss value based on the operating temperature.

[0048] The industrial computer is provided with a threshold value. When the capacitance or the converted dielectric loss value exceeds the threshold value, the industrial computer sends an alarm signal.

[0049] In some feasible solutions, the online monitoring device for dielectric loss and capacitance of a high-voltage bushing, wherein the current processing component includes:

[0050] A current amplifier is used to protect the circuit, and the current amplifier is connected to the leakage current sensor;

[0051] A filter, used for filtering clutter, wherein the filter is connected to the current amplifier;

[0052] A square wave shaping circuit, wherein the square wave shaping circuit is connected to the filter;

[0053] The analog-to-digital converter is electrically connected to the square wave shaping circuit and is used to convert the current signal into a digital signal; the analog-to-digital converter is connected to the industrial computer.

[0054] In some feasible solutions, the online monitoring device for dielectric loss and capacitance of a high-voltage bushing, wherein the voltage processing component includes:

[0055] A voltage amplifier is used to protect the circuit, and the voltage amplifier is connected to the voltage transformer;

[0056] A filter, used for filtering clutter, the filter being connected to the voltage transformer;

[0057] A square wave shaping circuit, wherein the square wave shaping circuit is connected to the filter;

[0058] The analog-to-digital converter is electrically connected to the square wave shaping circuit and is used to convert the voltage signal into a digital signal; the analog-to-digital converter is connected to the industrial computer.

[0059] In some feasible solutions, the online monitoring device for the dielectric loss and capacitance of the high-voltage bushing also includes an alarm device, which is connected to an industrial computer. The industrial computer is used to control the alarm device to send an alarm signal when the capacitance or dielectric loss value exceeds a threshold.

[0060] In this solution, the above-mentioned industrial computer has a preset threshold value. After the above-mentioned industrial computer is connected to the network, it will retrieve the current standard dielectric loss value and capacitance of the high-voltage bushing in real time. The above-mentioned threshold value is adjusted in real time according to the standard dielectric loss value and capacitance; the above-mentioned industrial computer compares the threshold value with the capacitance and the dielectric loss value after loss. When the above-mentioned capacitance or the converted dielectric loss value exceeds the threshold value, the above-mentioned industrial computer will send an alarm signal.

[0061] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0062] A leakage current sensor is provided on the inner wall of the end screen of the high-voltage bushing, and the leakage current sensor collects the leakage current of the high-voltage bushing during operation; the leakage current sensor is connected to the current processing component, and the current processing component is used to pre-process the current signal so as to measure the capacitance and dielectric loss value of the high-voltage bushing more accurately. The current processing component is connected to the microprocessor, and the microprocessor converts the leakage current into the sum of the fundamental component and each harmonic component, and transmits it to the industrial computer; the voltage transformer measures the operating voltage of the high-voltage bushing, and the voltage transformer is connected to the voltage processing component, and the voltage processing component is used to pre-process the voltage signal so as to measure the capacitance and dielectric loss value of the high-voltage bushing more accurately. The microprocessor converts the operating voltage of the high-voltage bushing into the sum of the fundamental component and each harmonic component, and transmits the conversion to the industrial computer; the industrial computer calculates the dielectric loss value and capacitance of the high-voltage bushing based on the leakage current and the sum of the fundamental component and each harmonic component of the operating voltage; the temperature sensor measures the operating temperature of the high-voltage bushing and transmits the conversion to the industrial computer. The temperature sensor is used to fully consider the influence of the measured temperature and perform a unified temperature conversion. The industrial computer obtains the converted dielectric loss value based on the dielectric loss value and the operating temperature. The industrial computer stores and displays the calculated dielectric loss value. The capacitance and dielectric loss value of the high-voltage bushing are accurately monitored through the unified temperature conversion and indirect measurement of the capacitance and dielectric loss value of the high-voltage bushing.

[0063] The industrial computer compares the threshold with the capacitance and the dielectric loss value after decompression. When the capacitance or the decompressed dielectric loss value exceeds the threshold, the industrial computer sends an alarm signal, thereby achieving the purpose of early warning by real-time monitoring of the capacitance and dielectric loss value of the high-voltage bushing. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the examples. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be considered as limiting the scope. A person of ordinary skill in the art can also derive other relevant drawings based on these drawings without inventive effort. In the drawings:

[0065] Figure 1 A flow chart of a method for online monitoring of dielectric loss and capacitance of a high-voltage bushing is provided for Example 1;

[0066] Figure 2 A system structure diagram of an online monitoring device for dielectric loss and capacitance of a high-voltage bushing is provided for Example 1;

[0067] Figure 3 A measurement circuit framework diagram of a voltage processing component and a current processing component is provided for Example 1.

[0068] Markings and corresponding parts names in the accompanying drawings:

[0069] 1-leakage current sensor, 2-current processing component, 3-microprocessor, 4-voltage transformer, 5-voltage processing component, 6-industrial computer, 7-temperature sensor, 8-alarm device. DETAILED DESCRIPTION

[0070] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0071] Example 1

[0072] like Figure 1-Figure 3 Embodiment 1 provides an online monitoring method for dielectric loss and capacitance of a high-voltage bushing. The online monitoring method for dielectric loss and capacitance of a high-voltage bushing comprises the following steps:

[0073] S1: A leakage current sensor 1 is provided on the inner wall of the high-voltage bushing end screen, and the leakage current sensor 1 collects the leakage current when the high-voltage bushing is in operation;

[0074] S2: The leakage current passes through the current processing component 2 and the microprocessor 3 in sequence;

[0075] S3: Voltage transformer 4 measures the operating voltage of the high-voltage bushing;

[0076] S4: The operating voltage passes through the voltage processing component 5 and the microprocessor 3 in sequence;

[0077] S5: The microprocessor 3 converts the operating voltage into the sum of the fundamental component and each harmonic component of the voltage signal, converts the leakage current into the sum of the fundamental component and each harmonic component of the current signal, and transmits the results to the industrial computer 6;

[0078] S6: The industrial computer 6 calculates the dielectric loss value and capacitance based on the leakage current and the sum of the fundamental component and each harmonic component of the operating voltage;

[0079] S7: The temperature sensor 7 measures the operating temperature of the high-voltage bushing and transmits the temperature to the industrial computer 6;

[0080] S8: The industrial computer 6 obtains the converted dielectric loss value based on the dielectric loss value and the operating temperature;

[0081] S9: The industrial computer 6 is provided with a threshold value. When the capacitance or the converted dielectric loss value exceeds the threshold value, the industrial computer 6 sends an alarm signal.

[0082] In a specific embodiment, the high-voltage bushing is located on a device such as a transformer or a current transformer. A leakage current sensor 1 is provided on the inner wall of the end screen of the high-voltage bushing. The leakage current sensor 1 collects the leakage current of the high-voltage bushing during operation. The leakage current sensor 1 is connected to a current processing component 2. The current processing component 2 is used to pre-process the current signal, including current amplification protection, filtering, square wave shaping, and analog-to-digital conversion. The current processing component 2 is connected to a microprocessor 3. The microprocessor 3 performs a discrete Fourier transform on the leakage current, converts the current signal into the sum of the fundamental component and each harmonic component, and transmits it to an industrial computer 6.

[0083] Leakage current as measured by leakage current sensor 1:

[0084] Where I0 is the DC component of the current; I km is the amplitude of each harmonic of current; β k is the phase angle of each harmonic of current (k=1,2,…,∞);

[0085] The substation is connected to the high-voltage bushing. The substation is used to provide the required operating voltage for the high-voltage bushing. The voltage transformer 4 measures the operating voltage of the high-voltage bushing through the substation. The voltage transformer 4 is connected to the voltage processing component 5. The voltage processing component 5 is used to pre-process the voltage signal, including current amplification protection, filtering, square wave shaping and analog-to-digital conversion. The voltage processing component 5 is connected to the microprocessor 3. The microprocessor 3 performs a discrete Fourier transform on the operating voltage of the high-voltage bushing, converts the voltage signal into the sum of the fundamental component and each harmonic component, and transmits it to the industrial control computer 6;

[0086] The operating voltage measured by voltage transformer 4 is:

[0087] Where U0 is the DC component of the voltage; U km is the amplitude of each harmonic of voltage; α k is the phase angle of each harmonic of voltage (k=1,2,…,∞);

[0088] The industrial computer 6 calculates the dielectric loss value and capacitance of the high-voltage bushing based on the leakage current and the sum of the fundamental component and each harmonic component of the operating voltage, and displays them;

[0089] according to

[0090] Among them, α1 and β1 are the fundamental phase angles of the operating voltage and leakage current respectively. Since the current flowing through the high-voltage bushing leads the voltage by 90°, the dielectric loss value of the high-voltage bushing is:

[0091] Calculation yields: tanδ = tan[arctan(C1 / C0)-arctan(D1 / D0)];

[0092] capacitance (where ω = 2πf, and f is 50 Hz);

[0093] The operating temperature of the high-voltage bushing is obtained by the temperature sensor 7, which is preferably a passive temperature sensor, and is transmitted to the industrial computer 6. The measurement time of the temperature sensor 7 is consistent with the leakage current measurement time and the operating voltage measurement time;

[0094] The industrial computer 6 obtains the dielectric loss value of the high-voltage bushing at a certain temperature through conversion, and displays the measured temperature and the converted bushing dielectric loss value on the system, such as the converted dielectric loss value of the high-voltage bushing at 20°C;

[0095] The conversion formula for dielectric loss value is:

[0096] Among them, tanδ1 and tanδ2 are the dielectric loss values ​​at temperatures t1 and t2 respectively;

[0097] The industrial computer 6 has a preset threshold value. After being connected to the network, the industrial computer 6 retrieves the current standard dielectric loss value and capacitance of the high-voltage bushing in real time. The threshold value is adjusted in real time according to the standard dielectric loss value and capacitance. The industrial computer 6 compares the threshold value with the capacitance and the dielectric loss value after loss. When the capacitance or the converted dielectric loss value exceeds the threshold value, the industrial computer 6 sends an alarm signal.

[0098] Preferably, the above thresholds are set with reference to the following: the difference between the capacitance of the high-voltage bushing after operation and the initial capacitance does not exceed ±5%; and the dielectric loss factor tanδ meets the requirements of the following table:

[0099] <![CDATA[U m (KV)]]> 126 / 72.5 252 / 363 ≥550 tanδ ≤0.01 ≤0.08 ≤0.007

[0100] The online monitoring device for dielectric loss and capacitance of high voltage bushing comprises:

[0101] A leakage current sensor 1 is arranged on the inner wall of the end screen of the high voltage bushing.

[0102] A current processing assembly 2 is connected with the leakage current sensor 1.

[0103] A microprocessor 3 is connected with the current processing assembly 2.

[0104] A voltage transformer 4 is used for measuring the operating voltage of the high voltage bushing.

[0105] A voltage processing assembly 5 is connected between the voltage transformer 4 and the microprocessor 3.

[0106] A temperature sensor 7 is used for measuring the operating temperature of the high voltage bushing.

[0107] An industrial computer 6 is connected with the microprocessor 3 and the temperature sensor 7, and is provided with a threshold value. The industrial computer 6 is used for calculating the capacitance and dielectric loss value of the high voltage bushing according to the data transmitted by the microprocessor 3 and the temperature sensor 7. When the capacitance and dielectric loss value exceeds the threshold value, the industrial computer 6 sends an alarm signal.

[0108] In a specific embodiment, the leakage current sensor 1 measures the leakage current signal of the high voltage bushing and transmits it to the current processing assembly 2. The current processing assembly 2 pre-processes the leakage current signal and transmits it to the microprocessor 3. The microprocessor 3 is an online monitoring terminal. The microprocessor 3 performs discrete Fourier transform on the leakage current, converts the current signal into the sum of the fundamental component and each harmonic component, and transmits it to the industrial computer 6.

[0109] The voltage transformer 4 measures the operating voltage of the high voltage bushing and transmits it to the voltage processing assembly 5. The voltage processing assembly 5 pre-processes the operating voltage signal and transmits it to the microprocessor 3. The microprocessor 3 performs discrete Fourier transform on the operating voltage, converts the voltage signal into the sum of the fundamental component and each harmonic component, and transmits it to the industrial computer 6.

[0110] The temperature sensor 7 measures the operating temperature of the high voltage bushing and transmits it to the industrial computer 6. The industrial computer 6 calculates the dielectric loss value and capacitance according to the sum of the fundamental component and each harmonic component of the leakage current and operating voltage, and calculates the converted dielectric loss value according to the operating temperature.

[0111] The industrial computer 6 is provided with a threshold value. When the capacitance or the converted dielectric loss value exceeds the threshold value, the industrial computer 6 sends out an alarm signal.

[0112] The online monitoring method and system for high-voltage bushing dielectric loss and capacitance comprehensively improves the accuracy of online bushing insulation status monitoring under complex operating conditions. The dielectric loss measurement accuracy and stability are improved by an order of magnitude compared to existing standards, as shown in the following table:

[0113]

[0114]

[0115] The above specific implementation methods further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An online monitoring method for dielectric loss and capacitance of a high-voltage bushing, characterized in that: The method comprises the following steps: S1: A leakage current sensor (1) is provided on the inner wall of the high-voltage bushing end screen, and the leakage current sensor (1) collects leakage current when the high-voltage bushing is in operation; S2: the leakage current passes through the current processing component (2) and the microprocessor (3) in sequence; The step S2 comprises: A1: The leakage current sensor (1) is connected to a current processing component (2), and the current processing component (2) performs current amplification processing, filtering processing, square wave shaping processing and analog-to-digital conversion processing on the leakage current in sequence; A2: the current processing component (2) is connected to the microprocessor (3), and the current processing component (2) transmits the processed leakage current to the microprocessor (3); S3: Voltage transformer (4) measures the operating voltage of the high-voltage bushing; S4: the operating voltage passes through the voltage processing component (5) and the microprocessor (3) in sequence; The step S4 comprises: C1: the voltage transformer (4) is connected to the voltage processing component (5), and the voltage processing component (5) performs voltage amplification processing, filtering processing, square wave shaping processing and analog-to-digital conversion processing on the operating voltage in sequence; C2: the voltage processing component (5) is connected to the microprocessor (3), and the voltage processing component (5) transmits the processed operating voltage to the microprocessor (3); S5: The microprocessor (3) converts the operating voltage into the sum of the fundamental component and each harmonic component of the voltage signal, converts the leakage current into the sum of the fundamental component and each harmonic component of the current signal, and transmits the converted data to the industrial control computer (6); S6: The industrial control computer (6) calculates the dielectric loss value and capacitance based on the leakage current, the fundamental component of the operating voltage, and the sum of the harmonic components; S7: The temperature sensor (7) measures the operating temperature of the high-voltage bushing and transmits the temperature to the industrial computer (6); S8: The industrial control computer (6) obtains the converted dielectric loss value according to the dielectric loss value and the operating temperature; S9: The industrial computer (6) is provided with a threshold value, and when the capacitance or the converted dielectric loss value exceeds the threshold value, the industrial computer (6) sends an alarm signal; Step S1, step S3 and step S7 are performed simultaneously; When the leakage current sensor (1) collects the leakage current of the high-voltage bushing, the voltage transformer (4) collects the operating voltage of the high-voltage bushing, and the collection time and frequency of the leakage current sensor (1) and the voltage transformer (4) are consistent; When the voltage transformer (4) collects the operating voltage of the high-voltage bushing, the temperature sensor (7) collects the operating temperature of the high-voltage bushing, and the collection time and frequency of the voltage transformer (4) and the temperature sensor (7) are consistent.

2. The online monitoring method for dielectric loss and capacitance of a high-voltage bushing according to claim 1, characterized in that: Step S5 includes: D1: The microprocessor (3) performs discrete Fourier transform on the operating voltage, converts the voltage signal into the sum of the fundamental component and each harmonic component, and transmits the result to the industrial control computer (6); D2: At the same time, the microprocessor (3) performs discrete Fourier transform on the leakage current, converts the current signal into the sum of the fundamental component and each harmonic component, and transmits it to the industrial control computer (6).

3. The online monitoring method for dielectric loss and capacitance of a high-voltage bushing according to claim 1, characterized in that: The step S9 includes: The industrial computer (6) is provided with a threshold value, and is connected to an alarm device (8). When the capacitance or the converted dielectric loss value exceeds the threshold value, the industrial computer (6) controls the alarm device (8) to send an alarm signal.

4. An online monitoring device for dielectric loss and capacitance of a high-voltage bushing based on the method according to any one of claims 1 to 3, characterized in that: include: A leakage current sensor (1), the leakage current sensor (1) being arranged on the inner wall of the end screen of the high-voltage bushing; A current processing component (2), the current processing component (2) being connected to the leakage current sensor (1); A microprocessor (3), the microprocessor (3) being connected to the current processing component (2); A voltage transformer (4), the voltage transformer (4) being used to measure the operating voltage of the high-voltage bushing; A voltage processing component (5), wherein the voltage transformer (4) is connected to the microprocessor (3) via the voltage processing component (5); A temperature sensor (7), the temperature sensor (7) is used to measure the operating temperature of the high-voltage bushing; An industrial control computer (6) is connected to the microprocessor (3) and the temperature sensor (7) respectively, and the industrial control computer (6) is provided with a threshold value. The industrial control computer (6) is used to calculate the capacitance and dielectric loss value of the high-voltage bushing based on data transmitted by the microprocessor (3) and the temperature sensor (7). When the capacitance and dielectric loss value exceed the threshold value, the industrial control computer (6) sends an alarm signal.

5. The online monitoring device for dielectric loss and capacitance of a high-voltage bushing according to claim 4, characterized in that: The current processing component (2) comprises: A current amplifier for protecting the circuit, wherein the current amplifier is connected to the leakage current sensor (1); A filter, used for filtering clutter, wherein the filter is connected to the current amplifier; A square wave shaping circuit connected to the filter; An analog-to-digital converter is electrically connected to the square wave shaping circuit and is used to convert the current signal into a digital signal; the analog-to-digital converter is connected to the industrial control computer (6).

6. The online monitoring device for dielectric loss and capacitance of a high-voltage bushing according to claim 5, characterized in that: The voltage processing component (5) comprises: A voltage amplifier for protecting the circuit, the voltage amplifier being connected to the voltage transformer (4); A filter for filtering clutter, wherein the filter is connected to the voltage transformer (4); A square wave shaping circuit connected to the filter; An analog-to-digital converter is electrically connected to the square wave shaping circuit and is used to convert the voltage signal into a digital signal; the analog-to-digital converter is connected to the industrial control computer (6).

7. The online monitoring device for dielectric loss and capacitance of a high-voltage bushing according to claim 4, characterized in that: It also includes an alarm device (8), which is connected to the industrial control computer (6). The industrial control computer (6) is used to control the alarm device (8) to send an alarm signal when the capacitance or dielectric loss value exceeds a threshold value.

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