Multi-ring sensor for transformer substation partial discharge detection and positioning and positioning method

Abstract

According to the multi-ring sensor for transformer substation partial discharge detection and positioning and the positioning method, a multi-ring sensor structure is formed by arranging a first magnetic ring and a second magnetic ring which are embedded with each other, are vertically placed and form an included angle of 90 degrees, and whether a discharge source exists or not is judged by measuring the induced voltage of the sensor; a measurement azimuth angle and a calculation result azimuth angle are obtained according to a positioning formula calculation result of a plurality of multi-ring sensors, the specific position of the area where the discharge source is located is obtained, re-confirmation is conducted by checking whether discharge equipment exists or not, and finally a positioning result is output. According to the invention, the acquisition of partial discharge signals can be realized, the positioning of the discharge signals can be realized, the reliability of the detection signals is improved by calculating the detection signal-to-noise ratio in real time, the loss of weak discharge signals is avoided, and the positioning accuracy is improved by analyzing and judging the positioning result. According to the invention, effective detection of partial discharge weak signals in a complex environment of industrial and mining enterprises can be met, and sudden insulation faults of equipment are avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of detection of power facilities / equipment, and in particular to a multi-loop sensor applied to on-line monitoring technology of partial discharge of a transformer substation and a related positioning method. BACKGROUND

[0002] The so-called partial discharge phenomenon refers to a discharge occurring between electrodes but not penetrating through the electrodes, which is caused by a weak point in the internal insulation of a device or a defect in a production process, and is a phenomenon of repeated breakdown and extinction under the action of a high electric field. It is manifested as breakdown of gas in insulation, partial breakdown of solid or liquid medium in a small range, or partial breakdown discharge caused by field strength concentration at edge and sharp corner parts of a metal surface. Since the energy of such discharge is small, it exists for a short time and does not affect the insulation strength of the electrical equipment. However, if the insulation of the electrical equipment continuously appears partial discharge under the operating voltage, the cumulative effect of these weak discharges will gradually deteriorate the dielectric properties of the insulation and expand the local defect, and finally lead to breakdown of the entire insulation.

[0003] The partial discharge phenomenon is a sign of insulation deterioration of power equipment. Carrying out partial discharge detection of the equipment and discovering the discharge source as early as possible can prevent accidents and ensure safe and reliable operation of the power system. At present, various detection methods have been developed at home and abroad for running defects of power equipment, such as:

[0004] 1. The detection of a transformer usually adopts the method of dissolved gas in oil, which is stable and reliable, and can effectively detect gradual faults caused by overheating and the like.

[0005] This detection method has the following shortcomings: for discharge defects, especially for rapidly developing defects, the effectiveness of this detection method is poor and cannot respond in a timely manner.

[0006] 2. The lightning arrester and the mutual inductor are usually monitored by measuring the current and the dielectric loss, which is effective for defects such as insulation dampness. This detection method also has problems of detection effectiveness and timeliness for discharge defects.

[0007] 3. The GIS on-line monitoring usually adopts the method of ultra-high frequency partial discharge detection. The application at home and abroad shows that this method is a direct and effective way for discharge faults, and has prevented the occurrence of many GIS partial discharge accidents.

[0008] The partial discharge detection of power equipment in China has a research foundation of several decades, especially the ultra-high frequency detection method and the high-frequency current detection method proposed in the past 30 years, which can be implemented for non-stop power detection and on-line monitoring, can detect internal insulation defects of power equipment, and can provide early warning for insulation faults of power equipment. The power equipment partial discharge on-line detection and on-line monitoring have been gradually applied and promoted.

[0009] For the steel, petrochemical, coal and other industries, the number of power supply equipment in a plant is often very large, and the working environment of the equipment is very complex. It is increasingly important to quickly, effectively and economically realize the detection and positioning of equipment discharge. With the gradual improvement of the lean management requirements of power equipment, the monitoring and diagnosis of insulation state have become the daily work of equipment operation and maintenance management.

[0010] However, through feedback on actual cases and on-site worker operations, it is found that although the above partial discharge online monitoring method is effective, the premise of implementing this method is to accurately locate the discharge point of the power equipment, so as to carry out equipment insulation state evaluation and develop corresponding equipment operation and maintenance strategies. Therefore, accurate positioning is an important prerequisite. However, due to the large number of types of substation equipment and the complex operation, the positioning of equipment discharge is a difficult problem in current partial discharge detection.

[0011] According to the differences in detection principles and implementation methods, the existing technology classifies the partial discharge detection and positioning methods of power equipment into the following categories, as follows:

[0012] 1. One-by-one exclusion method:

[0013] The one-by-one exclusion method is based on the effectiveness of discharge physical characteristic detection, that is, the closer the distance between the detection sensor and the measured equipment, the more obvious the signal characteristics. By detecting and comparing the measured equipment one by one, the discharge source can be identified, and finally the discharge source can be positioned.

[0014] This method is simple and effective to implement, but its work efficiency is extremely low and is not suitable for partial discharge monitoring of a large number of equipment.

[0015] 2. Acoustic-electric combined method:

[0016] The acoustic-electric combined method is based on the combination of ultrasonic detection and ultra-high frequency detection. It uses the difference in transmission distance between ultrasonic signals and ultra-high frequency signals, that is, first use ultra-high frequency to roughly locate the area, and then use ultrasonic signals to locate the specific equipment.

[0017] This method has high implementation effectiveness, but the implementation difficulty is relatively large. The main reason is that the accuracy of positioning depends heavily on the professional level of the detection personnel. In addition, since two detection methods are used at the same time, the situation of external interference in the field is also relatively serious, and the specific implementation efficiency will be greatly discounted.

[0018] 3. Radio frequency positioning method:

[0019] Radio frequency positioning method is based on spatial very high frequency array positioning technology to realize the positioning of discharge source, that is, using a detection array composed of four or more omnidirectional very high frequency sensors, the position of the discharge source is calculated by analyzing the time difference of the discharge signal to different sensors.

[0020] The method has high reliability and can realize effective positioning of the discharge source in a wide area space, but it needs a detection array composed of four omnidirectional very high frequency sensors, so the implementation cost is high and it is difficult to popularize in a large area.

[0021] In summary, the above-mentioned several partial discharge detection positioning methods of the prior art have their limitations for partial discharge detection and positioning of substation equipment, so there is an urgent need for a more convenient, efficient and economical detection and positioning method to meet the needs of partial discharge detection and positioning of substation equipment. SUMMARY

[0022] In order to solve the various problems of partial discharge detection and positioning of substation equipment in the prior art, the present application provides a multi-ring sensor and positioning method for substation partial discharge detection and positioning, aiming to change the limitations of substation discharge detection and positioning in the prior art and realize reliable detection of substation discharge source.

[0023] A multi-ring sensor for substation partial discharge detection and positioning, comprising a magnetic ring, characterized in that:

[0024] The magnetic ring has two, which are a first magnetic ring and a second magnetic ring;

[0025] The first magnetic ring and the second magnetic ring are mutually embedded and both are vertically placed, the ring body of the first magnetic ring and the ring body of the second magnetic ring form a 90° angle, forming a multi-ring sensor structure, and the internal space is uniformly distributed.

[0026] According to the multi-ring sensor for substation partial discharge detection and positioning of the present application, the first magnetic ring and the second magnetic ring have the same structure and are both made of multi-turn coil winding, forming a loop antenna structure.

[0027] According to the multi-ring sensor for substation partial discharge detection and positioning of the present application, the first magnetic ring and the second magnetic ring are circular, elliptical or rectangular.

[0028] A method for substation partial discharge detection and positioning based on the above-mentioned multi-ring sensor for substation partial discharge detection and positioning, the specific steps are as follows:

[0029] 1) Set the first magnetic ring and the second magnetic ring received induced electromotive force is E1 and E2, the first magnetic ring and the second magnetic ring composed of multi-loop sensor axis O and discharge source P parallel placement, discharge source P and the first magnetic ring plane angle is θ, discharge source P and the second magnetic ring plane angle is 90°-θ;

[0030] 2) When the first magnetic ring on the induction of partial discharge signal, its induction generated by the induced electromotive force E1 is calculated by the following formula:

[0031]

[0032] In the formula:

[0033] λ is the signal wavelength;

[0034] B is the signal magnetic induction intensity;

[0035] N is the number of turns of the antenna;

[0036] S is the antenna area;

[0037] μ is the relative magnetic permeability of the antenna ring;

[0038] θ is the angle between the discharge signal and the first magnetic ring;

[0039] 3) In step 2), the same reasoning can be used to prove that the second magnetic ring and the discharge signal come to the angle of substitution electromotive force E1 formula, and its induced electromotive force E2 is obtained, and the following formula is obtained:

[0040]

[0041]

[0042] 4) In steps 2) and 3), it is judged whether there is a discharge phenomenon, which is specifically:

[0043] After the detection starts, the voltage values output by the first magnetic ring and the second magnetic ring on each multi-loop sensor are measured first, and then the amplitude V of the discharge pulse is collected f and the background noise amplitude V o , and the discharge detection signal-to-noise ratio R=20log 10 (V f / V o ) is calculated, and finally the discharge detection signal-to-noise ratio R is compared with the preset signal-to-noise ratio R o , if R≥R o , it is judged that there is a suspected discharge;

[0044] It should be noted that the first magnetic ring and the second magnetic ring are not powered, and the output is an induced voltage.

[0045] 5) combined with the formula in step 2) and step 3), 3 multi-ring sensors are arranged, a single multi-ring sensor can only locate the approximate direction of the discharge source, combined positioning is adopted by using 3 multi-ring sensors, the measured azimuth angle and the calculated result azimuth angle are obtained according to the calculation results of the positioning formula of each multi-ring sensor, and finally the specific position of the discharge source P is obtained;

[0046] 6) if it is judged that there is suspected discharge in step 4), the specific position of the discharge source P obtained in step 5) is used to judge again whether the positioning is correct, specifically:

[0047] 6.1) confirm whether the deviation of the loop antenna positioning angle value of different multi-ring sensors is within a preset range;

[0048] 6.2) combined with the actual distribution of the equipment, it is directly viewed whether there is equipment that may occur discharge at the positioning direction;

[0049] After the above confirmation is completed, it is determined that the positioning result is correct, and the positioning result is output.

[0050] According to the method for partial discharge detection and positioning of a substation according to the application, in step 5), the number of multi-ring sensors is not less than 3, which is increased according to the specific situation on site, so that the detection and positioning accuracy is improved.

[0051] The multi-ring sensor and the positioning method for partial discharge detection and positioning of a substation according to the application have the following advantages

[0052] Advantages:

[0053] 1. Compared with the traditional method, the multi-ring sensor and the positioning method for partial discharge detection and positioning of a substation according to the application can realize the collection of partial discharge signals and the positioning of discharge signals, the method is convenient and reliable, the efficiency of partial discharge detection and positioning of substation equipment can be obviously improved, and the cost of power equipment operation and maintenance can be effectively reduced.

[0054] 2. The multi-ring sensor and the positioning method for partial discharge detection and positioning of a substation according to the application have the following advantages

[0055] 3. The multi-ring sensor and the positioning method for partial discharge detection and positioning of a substation according to the application can be effectively applied to partial discharge detection of power equipment, can meet the effective detection of weak partial discharge signals in complex environments of industrial and mining enterprises, can avoid sudden insulation faults of equipment, and can provide technical support for stable operation of equipment. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 A specific structure diagram of a multi-ring sensor for substation partial discharge detection positioning of the present application;

[0057] Figure 2 A layout diagram of a multi-ring sensor for substation partial discharge detection positioning of the present application;

[0058] Figure 3 A specific implementation effect diagram of a multi-ring sensor for substation partial discharge detection positioning of the present application;

[0059] Figure 4 A detection flowchart of a multi-ring sensor for substation partial discharge detection positioning of the present application.

[0060] In the figure: 1 - first magnetic ring, 2 - second magnetic ring, A - multi-ring sensor. DETAILED DESCRIPTION

[0061] The technical means, creative features, purposes and effects of a multi-ring sensor for substation partial discharge detection positioning and a positioning method of the present application will be further described below in combination with the drawings and examples.

[0062] EMBODIMENT

[0063] As shown in Figure 1 and Figure 2 A multi-ring sensor for substation partial discharge detection positioning includes magnetic rings, and there are two magnetic rings, which are a first magnetic ring 1 and a second magnetic ring 2.

[0064] The first magnetic ring 1 and the second magnetic ring 2 are mutually embedded and both are vertically placed, and the ring body of the first magnetic ring and the ring body of the second magnetic ring form a 90° angle, forming a multi-ring sensor A structure, and the internal space is uniformly distributed.

[0065] The first magnetic ring 1 and the second magnetic ring 2 have the same structure and are both wound with multi-turn coils to form a loop antenna structure.

[0066] The first magnetic ring 1 and the second magnetic ring 2 are circular, elliptical or rectangular.

[0067] As shown in Figure 4 A method for substation partial discharge detection positioning based on the above multi-ring sensor for substation partial discharge detection positioning, and the specific steps are as follows:

[0068] 1) Let the induced electromotive forces received by the first magnetic ring 1 and the second magnetic ring 2 be E1 and E2 respectively, as shown in Figure 2As shown, the middle axis O of the multi-loop sensor composed of the first magnetic ring and the second magnetic ring is parallel to the discharge source P, the angle between the discharge source P and the plane of the first magnetic ring is θ, and the angle between the discharge source P and the plane of the second magnetic ring is 90°-θ;

[0069] 2) When a partial discharge signal is induced on the first magnetic ring, the induced electromotive force E1 generated by the induction is calculated by the following formula:

[0070]

[0071] In the formula:

[0072] λ is the signal wavelength;

[0073] B is the signal magnetic induction intensity;

[0074] N is the number of turns of the antenna;

[0075] S is the antenna area;

[0076] μ is the relative magnetic permeability of the antenna loop;

[0077] θ is the angle between the discharge signal and the first magnetic ring;

[0078] 3) In step 2), by the same reasoning, the angle between the second magnetic ring and the discharge signal is substituted into the electromotive force E1 formula to obtain the induced electromotive force E2, and the following formula is obtained:

[0079]

[0080]

[0081] 4) In steps 2) and 3), it is determined whether there is a discharge phenomenon, which is specifically:

[0082] After the detection starts, the voltage values output by the first magnetic ring and the second magnetic ring on each multi-loop sensor A are measured first, and then the amplitude V of the discharge pulse is collected f and the amplitude V o of the background noise are calculated, and the discharge detection signal-to-noise ratio R=20log 10 (V f / V o ) is calculated, and finally the discharge detection signal-to-noise ratio R is compared with the preset signal-to-noise ratio R o , if R≥R o , it is determined that there is a suspected discharge;

[0083] 5) As Figure 3As shown, combined with the formula in step 2) and step 3), 3 multi-loop sensors are arranged, and a single multi-loop sensor can only locate the approximate direction of the discharge source, and the joint positioning of the 3 multi-loop sensors is adopted, and the measurement azimuth angle and the calculation result azimuth angle are obtained according to the calculation results of the positioning formula of each multi-loop sensor, and finally the specific position of the discharge source P is obtained;

[0084] 6) If it is judged that there is a suspected discharge in step 4), based on the specific position of the discharge source P obtained in step 5), it is judged again whether the positioning is correct, and specifically:

[0085] 6.1) Confirm whether the deviation of the loop antenna positioning angle value of different multi-loop sensors is within a preset range;

[0086] 6.2) Combined with the actual distribution of the equipment, it is directly viewed whether there is equipment that may occur discharge at the positioning direction;

[0087] After the above confirmation is completed, it is determined that the positioning result is correct, and the positioning result is output.

[0088] The number of multi-loop sensors is not less than 3 (3 in this embodiment), and is increased according to the specific situation on site to improve the detection positioning precision.

[0089] Compared with the conventional method, the multi-loop sensor for partial discharge detection and positioning of the substation of the present application can realize the collection of partial discharge signals and the positioning of discharge signals, the method is convenient and reliable to implement, and the efficiency of partial discharge detection and positioning of substation equipment can be obviously improved, and the cost of power equipment operation and maintenance can be effectively reduced. The multi-loop sensor for partial discharge detection and positioning of the substation of the present application has a more flexible and reliable detection method, improves the reliability of the detection signal by real-time calculation of the detection signal-to-noise ratio, and avoids the loss of weak discharge signals. The positioning accuracy is improved through analysis and judgment of the positioning result. The multi-loop sensor for partial discharge detection and positioning of the substation of the present application can be effectively applied to partial discharge detection of power equipment, effectively detects weak partial discharge signals in complex environments of industrial and mining enterprises, avoids sudden insulation faults of equipment, and provides technical support for stable operation of equipment.

[0090] The multi-loop sensor for partial discharge detection and positioning of the substation of the present application can be widely applied to power grids, steel, petroleum, coal and other industrial and mining enterprises, and partial discharge detection and positioning of power equipment of different voltage grades, and has strong application prospect.

[0091] However, it should be appreciated by those skilled in the art that the foregoing examples are merely illustrative of the application and should not be construed as limiting the scope of the application as defined by the claims.

Claims

1. A multi-ring sensor for detecting and locating partial discharge in a substation, comprising a magnetic ring, characterized in that: There are two magnetic rings, namely a first magnetic ring (1) and a second magnetic ring (2); The first magnetic ring (1) and the second magnetic ring (2) are interlocked and placed vertically, with the ring body of the first magnetic ring and the ring body of the second magnetic ring forming a 90° angle, forming a multi-ring sensor (A) structure, the internal space of which is evenly distributed.

2. A multi-ring sensor for partial discharge detection and positioning in a substation according to claim 1, characterized in that: The first magnetic ring (1) and the second magnetic ring (2) have the same structure and are both wound with multiple turns of coils to form a ring antenna structure.

3. A multi-ring sensor for partial discharge detection and positioning in a substation according to claim 1, characterized in that: The first magnetic ring (1) and the second magnetic ring (2) are circular, elliptical or rectangular.

4. A method for detecting and locating partial discharge in a substation, based on the multi-ring sensor for detecting and locating partial discharge in a substation according to any of the above claims, wherein the specific steps are as follows: 1) Assuming that the induced electromotive forces received by the first magnetic ring (1) and the second magnetic ring (2) are E1 and E2 respectively, the central axis O of the multi-ring sensor composed of the first magnetic ring and the second magnetic ring is placed parallel to the discharge source P, the angle between the discharge source P and the plane of the first magnetic ring is θ, and the angle between the discharge source P and the plane of the second magnetic ring is 90°-θ; 2) When the partial discharge signal is induced on the first magnetic ring, the induced electromotive force E1 is calculated by the following formula: Where: λ is the signal wavelength; B is the signal magnetic induction intensity; N is the number of antenna turns; S is the antenna area; μ is the relative magnetic permeability of the antenna ring; θ is the angle between the discharge signal and the first magnetic ring; 3) In step 2), similarly, the angle between the second magnetic ring and the discharge signal is substituted into the formula for electromotive force E1 to obtain its induced electromotive force E2, which can be obtained as follows: 4) In step 2) and step 3), determine whether there is a suspected discharge phenomenon, which is specifically: After the test starts, the voltage output by the first and second magnetic rings on each multi-ring sensor (A) is measured, and then the amplitude V of the discharge pulse is collected. f and background noise amplitude V o , and calculate the discharge detection signal-to-noise ratio R = 20log 10 (V f / V o ), and finally the discharge detection signal-to-noise ratio R is compared with the preset signal-to-noise ratio R o For comparison, if R≥R o , it is judged that there is suspected discharge; 5) Combining the formulas in steps 2) and 3), three multi-ring sensors are set. A single multi-ring sensor can only locate the approximate direction of the discharge source. Using the three multi-ring sensors for joint positioning, the measurement azimuth and the calculated azimuth are calculated based on the positioning formulas of each multi-ring sensor, ultimately determining the specific location of the area where the discharge source P is located. 6) If it is determined in step 4) that there is a suspected discharge, then based on the specific location of the area where the discharge source P is located obtained in step 5), it is again determined whether the positioning is correct, specifically: 6.1) Confirm whether the deviation of the loop antenna positioning angle values ​​of different multi-loop sensors is within the preset range; 6.2) Based on the actual distribution of equipment, directly check whether there is any equipment that may cause discharge in the positioning direction; After the above confirmation is completed, the positioning result is determined to be correct and the positioning result is output.

5. A method for detecting and locating partial discharge in a substation according to claim 4, characterized in that: In the step 5), the number of multi-ring sensors is not less than 3, and can be increased depending on the specific situation on site to improve the detection and positioning accuracy.

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