Dry-type reactor body temperature prediction method based on resistance change

Abstract

The invention relates to a dry-type reactor body temperature prediction method based on resistance change, and the method comprises the following steps: measuring voltages at two ends of a dry-type reactor through a voltage transformer, and obtaining the amplitude and angle of the voltages; the running current of the dry-type reactor is measured through a current transformer, and the amplitude and angle of the running current are obtained; solving an impedance angle according to the voltage angle and the current angle; according to the voltage amplitude and the current amplitude, the impedance value of the dry-type reactor is solved; according to the obtained impedance value and impedance angle of the dry-type reactor, the resistance value of the dry-type reactor can be solved; a metal material resistance value and temperature conversion formula is adopted, conversion is carried out, and a real-time temperature value is obtained; in order to obtain the temperature value more accurately, a multi-harmonic correction method, a multi-reference temperature correction method or a combined method is adopted, and temperature value errors caused by calculation errors of the resistance value of the dry-type reactor are eliminated; the method has the advantages of being simple in principle, practical, easy to implement, safe, reliable and capable of achieving real-time detection.

Description

Technical Field

[0001] The present invention belongs to the technical field of power maintenance status detection, and particularly relates to a method for predicting the temperature of a dry-type reactor body based on resistance change. Background Art

[0002] Dry-type reactors are important reactive power compensation devices in the power system. Due to their simple structure, low cost, excellent performance, and convenient maintenance, they are widely used in the power system. For currently operating dry-type reactors, with the extension of the operation years, in addition to the decline in insulation performance and failures caused by their own factors, the internal ventilation ducts may also be congested due to blockage and other factors, which affects the ventilation and heat dissipation capacity. The superposition of various factors makes dry-type reactors prone to failures, especially the fire accidents of dry-type reactors, which have a great impact on their safe operation; for currently operating dry-type reactors, there is a lack of effective detection means for their own failures, especially the measurement of their own temperature. Except for the classic infrared temperature measurement means, other methods such as thermocouple detection, sensor detection, and optical fiber detection all require installing various sensors on the dry-type reactor body. In addition to increasing costs, it will also change the structure of the dry-type reactor itself to a certain extent, causing distortion of the electric field and forming certain equipment hidden dangers; for non-contact detection methods, such as infrared temperature measurement detection, it is mostly used for on-site inspections, relying on detection personnel and intelligent inspection robots, and it is difficult to achieve real-time and non-blind-spot detection; therefore, it is very necessary to provide a method for predicting the temperature of a dry-type reactor body based on resistance change that is simple in principle, practical and feasible, safe and reliable, and capable of real-time detection. Summary of the Invention

[0003] (1) Technical Problems

[0004] In view of the above-mentioned current situation of the prior art, the present application mainly aims at the following technical problems:

[0005] 1. Most of the existing detection methods require installing various sensors on the dry-type reactor body. In addition to increasing costs, it will also change the structure of the dry-type reactor itself to a certain extent, causing distortion of the electric field and forming certain equipment hidden dangers;

[0006] 2. For non-contact detection methods, they are mostly used for on-site inspections, relying on detection personnel and intelligent inspection robots, and it is difficult to achieve real-time and non-blind-spot detection.

[0007] (2) Technical Solutions

[0008] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for predicting the temperature of a dry-type reactor body based on resistance change that is simple in principle, practical and feasible, safe and reliable, and capable of real-time detection.

[0009] The object of the present invention is achieved as follows: a dry-type reactor body temperature prediction method based on resistance value change, the method comprising the following steps:

[0010] Step 1: Measure the voltage across the dry-type reactor through a voltage transformer and obtain its amplitude U and angle θ U ;

[0011] Step 2: Measure the operating current of the dry-type reactor through a current transformer and obtain its amplitude I and angle θ I ;

[0012] Step 3: Based on the voltage angle θ U and the current angle θ I , calculate the impedance angle

[0013] Step 4: Based on the voltage amplitude U and the current amplitude I, calculate the impedance value Z of the dry-type reactor;

[0014] Step 5: Based on the obtained impedance value and impedance angle of the dry-type reactor, the resistance value R of the dry-type reactor can be calculated;

[0015] Step 6: Adopt the resistance-temperature conversion formula of metal materials and perform transformation to obtain the real-time temperature value t;

[0016] Step 7: In order to obtain the temperature value more accurately, adopt the multi-harmonic correction method, the multi-reference temperature correction method or a combination thereof to eliminate the temperature value error caused by the calculation error of the resistance value of the dry-type reactor.

[0017] Further, the impedance angle in Step 3 is calculated by the following formula:

[0018] Further, the impedance value Z in Step 4 is calculated by the following formula:

[0019] Further, the resistance value R in Step 5 is calculated by the following formula:

[0020] Further, the resistance-temperature conversion formula of metal materials in Step 6 is specifically: In the formula, R is the resistance value calculated according to Step 5; R0 is the reference resistance value at the reference temperature t0; T is the resistance conversion conversion coefficient; t is the temperature value when the resistance of the dry-type reactor is R; by transforming the above formula, the real-time temperature value t can be obtained as:

[0021] Further, the multi-harmonic correction method in Step 7 is specifically: under the condition of rich harmonic content, by obtaining the amplitudes U of the fundamental wave and different harmonics of the voltageh , Angle The amplitude I of the current h , Angle where h is the harmonic order; and according to the above steps 1-6, multiple real-time temperature values t are predicted and compared with the actual temperature, and multiple predicted temperature values are converted into a predicted temperature through the mean square error and root mean square algorithms to reduce the calculation error.

[0022] Further, the multi-reference temperature correction method in step 7 is specifically as follows: when the power quality is high and the harmonic content is low, multiple reference temperatures can be set in step 5, the errors between the prediction results and the actual values at different reference temperatures are calculated, a correction algorithm is set, and the predicted temperature in step 6 is corrected.

[0023] (III) Beneficial effects

[0024] 1. The present invention first calculates the real-time resistance value of the dry-type reactor through the actually measured voltage and current, and converts it into the real-time temperature value of the dry-type reactor according to the real-time resistance value;

[0025] 2. The method of the present invention does not need to transform the structure of the on-site dry-type reactor or install various sensors to achieve it. The principle is simple and easy to implement, and it has the advantages of safety, reliability and high accuracy. It can monitor the body temperature value of the dry-type reactor in real time, and give corresponding warnings when there are abnormal temperatures in the body, avoiding the occurrence of faults in the dry-type reactor and affecting the safe operation of the equipment, which is of great significance for ensuring the safety and stability of the power system. Brief description of the drawings

[0026] Figure 1 It is a schematic diagram of the dry-type reactor in operation of the present invention.

[0027] Figure 2 It is an equivalent circuit diagram of the dry-type reactor operation of the present invention.

[0028] Figure 3 It is a voltage-current vector diagram of the present invention. Specific embodiments

[0029] For dry-type reactors, their functional and structural principles result in a large amount of heat generation during operation, making them common heat-generating equipment in the power system. The allowable temperature values of dry-type reactors under different insulation classes are different. For example, for dry-type reactors with F-class insulation, the maximum allowable temperature is 155°C, and the temperature rise limit is 100K. Through the measurement of dry-type reactors during on-site operation, generally speaking, in hot weather, the on-site operation temperature can reach about 100°C, and in cold winter, it can also reach above 50°C. For dry-type reactors, their windings are generally made of aluminum materials. As the temperature rises, the resistance value of the wire per unit length will increase with the increase in temperature and can be converted through corresponding formulas. Therefore, for the reactance during actual operation, by using voltage transformers and current transformers, its operating voltage and operating current are measured, its resistance value is obtained through calculation, and based on the conversion relationship between the resistance value and temperature, the temperature value of its body is obtained, which is feasible in principle. Therefore, studying a new method for detecting the temperature of the dry-type reactor body, making it simple in principle, practical and easy to implement, and safe and reliable, and being able to detect the temperature state of the dry-type reactor body in real time, is of great significance for ensuring the stable operation of dry-type reactors.

[0030] The following further describes the present invention in conjunction with embodiments and / or drawings.

[0031] Embodiment 1

[0032] As Figures 1 - 3 shown, a method for predicting the temperature of the dry-type reactor body based on the change in resistance value, the method includes the following steps:

[0033] Step 1: Measure the voltage across the dry-type reactor through a voltage transformer and obtain its amplitude U and angle θ U ;

[0034] Step 2: Measure the operating current of the dry-type reactor through a current transformer and obtain its amplitude I and angle θ I ;

[0035] Step 3: Based on the voltage angle θ U and the current angle θ I , calculate the impedance angle The impedance angle The solution formula is:

[0036] Step 4: Based on the voltage amplitude U and the current amplitude I, calculate the impedance value Z of the dry-type reactor. The solution formula for the impedance value Z is:

[0037] Step 5: Based on the obtained impedance value and impedance angle of the dry-type reactor, the resistance value R of the dry-type reactor can be calculated. The solution formula for the resistance value R is:

[0038] Step 6: Use the resistance-temperature conversion formula for metal materials and transform it to obtain the real-time temperature value t. The resistance-temperature conversion formula for metal materials is specifically as follows: In the formula, R is the resistance value calculated according to Step 5; R0 is the reference resistance value at the reference temperature t0. The reference temperature t0 and the reference resistance value R0 can be measured when the equipment is powered off, or the real-time resistance value and the calculated impedance value measured by infrared temperature measurement or other means at a certain moment can be used as the benchmark; T is the resistance conversion conversion coefficient, which is different for different materials. For aluminum materials, this value is generally taken as 225; t is the temperature value when the resistance of the dry-type reactor is R. Transforming the above formula, the real-time temperature value t can be obtained as:

[0039] For dry-type reactors, they are equipment with strong inductance and low resistance, and the resistance value is small. The calculation error of the resistance value will bring an error in the temperature value. In order to obtain the temperature value more accurately and further eliminate the calculation error, a multi-harmonic correction method, a multi-reference temperature correction method or a combination thereof (combining the above two predicted temperatures for comprehensive correction) is adopted to improve the calculation accuracy.

[0040] The multi-harmonic correction method in Step 7 is specifically as follows: Under the working conditions with rich harmonic content, by obtaining the amplitudes U h and angles of the fundamental wave and different harmonics of the voltage, and the amplitudes I h and angles of the current, where h is the harmonic order; and according to the above Steps 1-6, multiple real-time temperature values t are predicted and compared with the actual temperature. Through the mean square error and root mean square algorithms, multiple predicted temperature values are converted into a predicted temperature to reduce the calculation error.

[0041] The multi-reference temperature correction method in Step 7 is specifically as follows: Under the condition of high power supply quality and low harmonic content, multiple reference temperatures can be set in Step 5, the errors between the predicted results and the actual values at different reference temperatures are calculated, and a correction algorithm is set to correct the predicted temperature in Step 6.

[0042] In summary, through the proposed method for predicting the temperature of the dry-type inductor body based on the change of resistance value, the present invention can realize the real-time monitoring of the temperature of the dry-type reactor body. The principle is simple and easy to implement, with high reliability, and can be realized without modifying the equipment; through the method of the present invention, an effective monitoring means can be provided for the safe operation of the on-site dry-type reactor, and a comprehensive diagnosis can be carried out in a timely manner when the dry-type reactor has abnormal temperature rise, avoiding the equipment running with defects and ensuring the safety of the equipment.

[0043] The present invention relates to a method for predicting the temperature of the body of a dry-type reactor based on resistance value changes. In use, by measuring the voltage across the dry-type reactor and combining it with the current flowing through the dry-type reactor, the real-time resistance value of the dry-type reactor can be obtained through calculation. By combining the resistance-temperature conversion formula and through the comprehensive prediction of temperatures under multiple temperature reference values and different harmonics, the temperature of the body of the dry-type reactor can be accurately obtained. The present invention is used to monitor the temperature of the body of a running dry-type reactor. When the body temperature rises abnormally, timely warnings can be given to avoid the operation of the dry-type reactor in a defective state, which is of great significance for ensuring the safe operation of the dry-type reactor. The present invention has the advantages of simple principle, practical feasibility, safety and reliability, and can perform real-time detection.

[0044] Embodiment 2

[0045] As Figures 1 - 3 shown, a method for predicting the temperature of the body of a dry-type reactor based on resistance value changes, the method comprising the following steps:

[0046] Step 1: Measure the voltage across the dry-type reactor through a voltage transformer, and obtain its amplitude U and angle θ U ;

[0047] Step 2: Measure the operating current of the dry-type reactor through a current transformer, and obtain its amplitude I and angle θ I ;

[0048] Step 3: Based on the voltage angle θ U and the current angle θ I , calculate the impedance angle

[0049] Step 4: Based on the voltage amplitude U and the current amplitude I, calculate the impedance value Z of the dry-type reactor;

[0050] Step 5: Based on the obtained impedance value and impedance angle of the dry-type reactor, the resistance value R of the dry-type reactor can be calculated;

[0051] Step 6: Use the resistance-temperature conversion formula for metal materials and perform transformation to obtain the real-time temperature value t;

[0052] Step 7: In order to obtain the temperature value more accurately, adopt a multi-harmonic correction method, a multi-reference temperature correction method or a combination thereof to eliminate the temperature value error caused by the calculation error of the resistance value of the dry-type reactor.

[0053] In the present invention, for specific applications: for a running dry-type reactor, it is usually wound with multiple layers of coils, has a simple structure, has a large current during operation, and is an important heat-generating device at the power site. The dry-type reactors operating on-site, such as Figure 1As shown; for dry-type reactors, which are strongly inductive devices, the reactance value is the main component in their impedance values. However, since they are made of wire windings and the wire is relatively long, there is also a certain resistance component. Its equivalent circuit diagram is as Figure 2 shown.

[0054] It can be seen from Figure 2 that a dry-type reactor can be equivalent to a series structure of an inductor L and a resistor R. After on-site installation, the spatial environment has been determined, so the inductance value L is basically fixed under fault-free conditions, while the resistance value R changes with the operating temperature. Therefore, by calculating the resistance R and combining the temperature conversion coefficient, the body temperature value of the dry-type reactor can be calculated.

[0055] For equipment operating on-site, a voltage transformer can be configured to measure the voltage u across the dry-type reactor, and a current transformer can be configured to measure the current i flowing through the dry-type reactor; when the voltage u across the dry-type reactor is obtained, it can be converted into a vector form. Use U to represent the amplitude of the terminal voltage u, and use θ U to represent the angle of the terminal voltage; similarly, when the current i flowing through the dry-type reactor is obtained, it can be converted into a vector form. Use I to represent the amplitude of the flowing current i, and use θ I to represent the angle of the flowing current. In Figure 2 , taking the current as the reference value, a vector diagram of the voltage can be drawn, as Figure 3 shown.

[0056] Combined with Figure 3 the vector diagram in, the impedance angle can be calculated, the impedance value can be calculated, the resistance value Combined with the resistance-temperature conversion formula for metal materials, In this formula, R is the resistance value calculated according to step 5; R0 is the reference resistance value at the reference temperature t0. The reference temperature t0 and the reference resistance value R0 can be measured during equipment outage, or the real-time resistance value and the calculated impedance value measured by infrared thermometry or other means at a certain moment can be used as the reference; T is the resistance conversion factor, which is different for different materials. For aluminum materials, this value is generally taken as 225; t is the temperature value when the resistance of the dry-type reactor is R;

[0057] By transforming the above formula, the real-time temperature value t can be obtained as:

[0058] Since the dry-type reactor is a strongly inductive device with a large inductance value and a small resistance value, in order to eliminate calculation errors, the following three schemes can be adopted for correction to eliminate calculation errors.

[0059] ①Adopt the multi-harmonic correction method: In the case of harmonics, the measured voltage and current can be respectively subjected to Fourier decomposition to obtain the voltage amplitude U h , voltage angle , current amplitude I h and current angle where h is the harmonic order.

[0060] The impedance angle and impedance value under different harmonics can be calculated, which are respectively Calculate the resistance value under different harmonics as Using different R h values, perform temperature prediction respectively to obtain multiple predicted temperatures t h ; Correct the multiple predicted temperatures t h . The average value, root mean square or other prediction methods can be adopted for synthesis and corrected to a predicted temperature t for output.

[0061] Specific implementation example is as follows: In a certain prediction, multiple temperatures t h are predicted through the resistance values under different harmonics. At this time, the true temperature t of the dry-type reactor can be obtained through means such as infrared temperature measurement. Weight t h , such as t = k1t1 + k2t2 +... + k h t h , where each k value is a weighting coefficient; Through h times of prediction, each k value can be obtained. Then, in subsequent predictions, based on the known weighting values, the predicted temperature is weighted and corrected, which can further improve the prediction accuracy; Correct the predicted temperatures t h under different harmonics. The above is only a schematic method, and other comprehensive weighted prediction methods can also be adopted.

[0062] ②Adopt the multi-reference correction method: In , at the reference temperature t0, calculate the predicted temperature t1 and the actual temperature t2; Record multiple reference temperature values as shown in the following table.

[0063] Serial number 1 2 3 4 5 6 <![CDATA[Reference temperature t0]]> <![CDATA[a1]]> <![CDATA[a2]]> <![CDATA[a3]]> <![CDATA[a4]]> <![CDATA[a5]]> <![CDATA[a6]]> <![CDATA[Predicted temperature t1]]> <![CDATA[x1]]> <![CDATA[x2]]> <![CDATA[x3]]> <![CDATA[x4]]> <![CDATA[x5]]> <![CDATA[x6]]> <![CDATA[Actual temperature t2]]> <![CDATA[y1]]> <![CDATA[y2]]> <![CDATA[y3]]> <![CDATA[y4]]> <![CDATA[y5]]> Y

[0064] Perform comprehensive conversion: In the above table, to calculate the actual temperature Y at the 6th time, various weighted algorithms can be adopted. A simple schematic is to take the ratio of the actual temperature to the predicted temperature. For example, from the above table, we can get: k1 = y1 / x1, k2 = y2 / x2, k3 = y3 / x3, k4 = y4 / x4, k5 = y5 / x5. Calculate the mean value k = (k1 + k2 + k3 + k4 + k5) / 5, then Y = k * x6.

[0065] The above is only an illustration of a conversion method for reducing calculation errors. More reference temperature values or other more comprehensive conversion methods can also be adopted; the two comprehensive conversion methods of the multi-harmonic correction method and the multi-reference correction method can also be comprehensively applied.

[0066] In summary, for the dry-type reactor in operation, by using the voltage measured by the voltage transformer and the current measured by the current transformer, and combining with the metal material temperature conversion formula, the real-time prediction of the temperature of the dry-type reactor body can be realized; in order to further eliminate calculation errors and reduce the accuracy of the dry-type reactor temperature prediction, the multi-harmonic prediction method and the multi-reference prediction method are also proposed, or they can be further comprehensively applied.

[0067] The present invention is a method for predicting the temperature of the dry-type reactor body based on the change of resistance value. In use, the present invention can obtain the real-time resistance value of the dry-type reactor by measuring the voltage across the dry-type reactor and combining with the current flowing through the dry-type reactor, combining with the resistance-temperature conversion formula, and by changing multiple temperature reference values and comprehensively predicting the temperature under different harmonics, the temperature of the dry-type reactor body can be accurately obtained; the present invention is used to monitor the temperature of the dry-type reactor body in operation, and can give an early warning in time when the body temperature rises abnormally, avoiding the dry-type reactor from operating in a defective state, which has important significance for ensuring the safe operation of the dry-type reactor; the present invention has the advantages of simple principle, practical feasibility, safety and reliability, and can be detected in real time.

Claims

1. A dry-type reactor body temperature prediction method based on resistance value change, characterized in that: The method includes the following steps: Step 1: Measure the voltage across the dry-type reactor through a potential transformer and obtain its amplitude U and angle θ U ; Step 2: Measure the operating current of the dry-type reactor through a current transformer, and obtain its amplitude I and angle θ I ; Step 3: Based on the voltage angle θ U and the current angle θ I , calculate the impedance angle Step 4: According to the voltage amplitude U and the current amplitude I, calculate the impedance value Z of the dry-type reactor; Step 5: According to the obtained impedance value and impedance angle of the dry-type reactor, the resistance value R of the dry-type reactor can be calculated; Step 6: Use the resistance-temperature conversion formula of the metal material and transform it to obtain the real-time temperature value t; Step 7: In order to obtain the temperature value more accurately, adopt the multi-harmonic correction method, the multi-reference temperature correction method or the combination thereof to eliminate the temperature value error caused by the calculation error of the resistance value of the dry-type reactor.

2. The dry-type reactor body temperature prediction method based on resistance value change according to claim 1, characterized in that: The impedance angle in step 3 The solution formula is:

3. The dry-type reactor body temperature prediction method based on resistance value change according to claim 1, characterized in that: The impedance value Z solving formula in the said step 4 is as follows:

4. The dry-type reactor body temperature prediction method based on resistance value change according to claim 1, characterized in that: The resistance value R solving formula in the said step 5 is as follows:

5. The dry-type reactor body temperature prediction method based on resistance value change according to claim 1, characterized in that: The resistance-temperature conversion formula for the metal material in step 6 is specifically as follows: In the formula, R is the resistance value calculated according to step 5; R0 is the reference resistance value at the reference temperature t0; T is the resistance conversion conversion factor; t is the temperature value when the dry-type reactor resistance is R; Transforming the above formula, the real-time temperature value t can be obtained as:

6. The dry-type reactor body temperature prediction method based on resistance value change according to claim 1, wherein: The multi-harmonic correction method in step 7 is specifically as follows: under the condition of rich harmonic content, by obtaining the amplitude U of the voltage under the fundamental wave and different harmonics h , angle , the amplitude I of the current h , angle where h is the harmonic order; and according to the above steps 1-6, multiple real-time temperature values t are predicted and compared with the actual temperature, and the multiple predicted temperature values are converted into a predicted temperature through the mean square error and root mean square algorithms to reduce the calculation error.

7. The dry-type reactor body temperature prediction method based on resistance value change according to claim 6, wherein: The multi-reference temperature correction method in the said Step 7 is specifically as follows: in the case of high power supply quality and low harmonic content, multiple reference temperatures can be set in Step 5, the errors between the predicted results and the actual values at different reference temperatures are calculated, a correction algorithm is set, and the predicted temperature in Step 6 is corrected.

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