CN112834975B - Comprehensive calibration method and system for ultrahigh frequency partial discharge sensor - Google Patents
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Abstract
A comprehensive calibration method and a comprehensive calibration system for an ultrahigh frequency partial discharge sensor are disclosed, wherein S parameters and effective heights of a tested ultrahigh frequency sensor are measured according to a preset number of scanning points in a preset detection frequency band, and the return loss, the real bandwidth, the insertion loss, the effective coverage working frequency band, the high gain working frequency band and the real average effective height of the ultrahigh frequency partial discharge sensor are subjected to multi-dimensional comprehensive calibration by using a detection result and a historical value thereof. The invention realizes the multi-dimensional comprehensive evaluation of the sensor verification, overcomes the defects of lack of related definitions and parameter requirements in the existing verification method, solves the problems that the traditional evaluation method is general to each parameter in the whole detection frequency range, has insufficient utilization of a large amount of characteristic information, masks unqualified characteristic parameters in the frequency division range and has poor sensor performance, and investigates the change condition of the sensor characteristic along with the time dimension and the influence condition of the sensor characteristic by the operating environment.
Description
Technical Field
The invention belongs to the technical field of detection and calibration of ultrahigh frequency partial discharge sensors of power equipment, and particularly relates to a comprehensive calibration method and system of ultrahigh frequency partial discharge sensors.
Background
Ultrahigh frequency partial discharge detection is an effective method for finding insulation defects inside electric equipment and is widely used in the year. The ultrahigh frequency sensor is the core of a detection system and has a crucial influence on detection sensitivity and diagnostic analysis reliability.
At present, the research and manufacturing mechanisms of ultrahigh frequency sensors are numerous, products are different, the design of unified specification and reasonable parameter requirements are not restricted, and the key problems are the important guarantee for correctly applying the ultrahigh frequency method.
The existing ultrahigh frequency detection system also has the problems of false alarm and missing report in application, and one reason is that the sensor has the problems of insufficient sensitivity or bandwidth and the like. For the definition of the sensitivity of the sensor, the average effective height is mostly evaluated in the industry at present, the parameters cannot completely reflect the real bandwidth and the sensitivity of the sensor, and the performance of the sensor is limited in description. The research developed by researchers at home and abroad mainly focuses on signal analysis and processing, but the importance on the verification and bandwidth definition of the sensor is insufficient.
The ultrahigh frequency sensor depends on the single evaluation effect of the average effective height, and the deepened application of the ultrahigh frequency detection technology is limited. Other important parameters for performance index evaluation are searched, which are the key for measuring and comparing the performance of the sensor, and are also important contents for further optimizing and improving the ultrahigh frequency technology evaluation system.
The traditional verification method only focuses on a certain single-dimensional performance parameter, the performance and arrangement condition of the sensor are difficult to verify comprehensively and accurately, meanwhile, the characteristic that the performance parameter changes along with the frequency is not focused sufficiently, and the characteristic information embodied by the performance parameter in a local frequency range is often ignored. On the other hand, an online verification method is lacked for built-in GIS ultrahigh frequency sensors which are installed and operated on site, and the performance of the built-in GIS ultrahigh frequency sensors is difficult to measure.
Therefore, the existing ultrahigh frequency sensor calibration method is difficult to meet the current actual detection and application requirements, and a more perfect and reliable ultrahigh frequency sensor calibration system and method are needed to solve the problem.
Disclosure of Invention
In order to solve the defects in the prior art, the invention aims to provide a detection and verification technology of an ultrahigh frequency partial discharge sensor of power equipment, wherein the bandwidth and the gain are defined by detecting the return loss, the insertion loss and the effective height, so that the checking dimension and the integrity of the sensor verification are improved.
The invention adopts the following technical scheme. The invention provides a comprehensive verification method of an ultrahigh frequency partial discharge sensor, which comprises the steps of measuring S parameters and effective heights of a tested ultrahigh frequency sensor according to a preset number of scanning points in a preset detection frequency band, and performing multi-dimensional comprehensive verification on return loss, real bandwidth, insertion loss, effective coverage working frequency band, high-gain working frequency band and real average effective height of the ultrahigh frequency partial discharge sensor by using a detection result and a historical value thereof.
Preferably, the comprehensive verification method includes the steps of:
and 4, comparing the effective height detection result of the tested ultrahigh frequency sensor with the effective height historical value, and checking the change conditions of the high-gain working frequency band and the real average effective height.
Preferably, step 1 comprises:
measuring the S11 or S22 parameter curve of the tested ultrahigh frequency sensor, and ensuring that the S11 or S22 parameter is less than a first threshold value T A The frequency range of (A) is used as the true bandwidth of the tested UHF sensor, i.e. the straight line S11 is T A Intersecting the S11 parameter curve, or using the straight line S22 ═ T A Intersecting with the S22 parameter curve, the S11 or S22 parameter curve is T-T at the straight line S11 A Or S22 ═ T A At least one frequency range corresponding to the lower part is the real bandwidth of the tested ultrahigh frequency sensor, and an S11 or S22 parameter curve and a straight line S11 is T A Or S22 ═ T A The intersection point of (a) is taken as the cut-off frequency corresponding to the real bandwidth frequency range;
measuring the S21 or S12 parameter curve of the tested ultrahigh frequency sensor, and enabling the S21 or S12 parameter to be larger than a certain set second threshold value T B As an effective coverage operating band for two adjacent uhf sensors, i.e. using the straight line S21 ═ T B Intersecting the S21 parameter curve, or using the straight line S12 ═ T B Intersecting with the S12 parameter curve, the S21 or S12 parameter curve is T-T at the straight line S21 B Or S12 ═ T B At least one frequency range corresponding to the upper part is an effective coverage working frequency band.
Preferably, step 2 comprises:
comparing the detection results of the S11 or S22 parameters, analyzing the amplitude difference on each frequency to obtain the change condition of the return loss, and analyzing that the S11 or S22 parameter is smaller than a first threshold value T A The change condition of the real bandwidth of the sensor is obtained, and the change condition of each frequency amplitude and bandwidth compared with each historical value is required to be smaller than a specified allowable range.
Preferably, step 2 comprises:
comparing the detection results of the S21 or S12 parameters, analyzing the amplitude difference on each frequency to obtain the change condition of the insertion loss, and analyzing whether the S21 or S12 parameter is larger than a certain second threshold value T B Frequency ofThe frequency range change condition obtains the change condition of the effective coverage working frequency bands of two adjacent ultrahigh frequency sensors, and the change condition of each frequency amplitude and the effective coverage working frequency bands of the two adjacent ultrahigh frequency sensors are required to be smaller than a specified allowable range compared with each historical value.
Preferably, step 3 comprises:
with the effective height being greater than a third threshold value T C The frequency range of (1) is used as the high-gain working frequency band of the tested sensor, and the average effective height of the tested sensor in the high-gain working frequency band is used as the real average effective height, that is, the straight line H is T C Intersecting the effective height curve, one or more intersections may be formed, which are bounded by the intersections, the effective height curve lying on a straight line H ═ T C At least one frequency range corresponding to the upper part is the high-gain working frequency band delta f of the tested ultrahigh frequency sensor gain For high gain operating band Δ f gain Average effective height in the inner part, i.e. obtaining true average effective height
Preferably, step 4 comprises:
comparing the detection results of the effective heights, and analyzing that the effective heights at all frequencies are greater than a third threshold value T C Obtaining the change condition of the high-gain working frequency band according to the change condition of the frequency range, and analyzing the change condition of the average effective height of the tested sensor in the current high-gain working frequency band to obtain the change condition of the real average effective height; the variation of the high-gain operating frequency band and the actual average effective height compared with the respective historical values is required to be less than the specified allowable range.
Preferably, the adopted preset detection frequency band can be [300MHz, 3GHz ]; or
A subset in the range of [300MHz and 3GHz ] is adopted as a preset detection frequency band; or
And (3) adopting the subset in the range of [300MHz and 3GHz ] as a preset detection frequency band and dividing the subset into a plurality of frequency bands for verification respectively.
Preferably, the method further comprises the following steps:
when the built-in ultrahigh frequency sensor of the power transformation equipment in operation is checked, the induced voltage value between the core wire of the reserved joint and the shell ground wire is recorded and compared with the historical result to be used as a reference for checking the characteristic change condition of the tested ultrahigh frequency sensor.
Another aspect of the present invention provides a comprehensive calibration system for an uhf partial discharge sensor based on the comprehensive calibration method, including:
the system comprises a measuring module, a data processing module, a checking and analyzing module and a measuring module, wherein the measuring module is used for measuring S parameters and effective heights of the tested ultrahigh frequency sensor in a preset detection frequency band according to a preset number of scanning points; the data processing module is used for comparing the S parameter detection result of the tested ultrahigh frequency sensor with the S parameter historical value and comparing the effective height detection result of the tested ultrahigh frequency sensor with the effective height historical value; and the checking analysis module is used for checking whether the return loss, the real bandwidth, the insertion loss, the effective coverage working frequency band, the high-gain working frequency band and the real average effective height meet the requirements or not.
Compared with the prior art, the method has the advantages that an ultrahigh frequency partial discharge sensor inspection and evaluation method system is established, the evaluation methods for the return loss, the real bandwidth, the insertion loss, the effective coverage working frequency band, the high-gain working frequency band and the real average effective height of the sensor are covered, the check dimension of the sensor inspection is enriched, and the multi-dimensional inspection and the effective evaluation for the sensitivity and the omnibearing performance of the sensor are realized. The beneficial effects are as follows:
(1) the invention considers the sensor characteristic conditions, the arrangement conditions and the gain performance of the sensor in different frequency bands, and realizes the multi-dimensional comprehensive evaluation of the sensor verification;
(2) the method defines the real bandwidth, the effective coverage working frequency band, the high-gain working frequency band and the real average effective height, gives specific evaluation indexes, and makes up the defects of lack of related definitions and parameter requirements in the existing verification method;
(3) in the verification and transmission process, the preset detection frequency band is divided more carefully, so that the problems that each parameter is generalized in the whole detection frequency range, a large amount of characteristic information is not fully utilized, the characteristic parameters are unqualified in the cover frequency division range, and the performance of the sensor is poor in the traditional evaluation method are solved;
(4) when the current performance state of the sensor is checked, the change condition of the sensor characteristic along with the time dimension and the condition influenced by the operating environment are inspected by comparing the S parameter detection result, the effective height detection result and the longitudinal history of the induced voltage value between the reserved joint core wire and the shell ground wire.
Drawings
FIG. 1 is a flow chart of a comprehensive calibration method for an UHF partial discharge sensor according to the present invention;
FIG. 2 is a schematic diagram of a two-port network;
FIG. 3 is a schematic diagram of obtaining a real bandwidth of a tested UHF sensor;
FIG. 4 is a schematic diagram of obtaining an effective coverage working frequency band of the tested UHF sensor;
FIG. 5 is a schematic diagram of obtaining a high-gain operating frequency band and a true average effective height of a high-frequency sensor to be tested;
fig. 6 is a schematic diagram illustrating division of preset detection frequency bands.
Detailed Description
The present application is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present application is not limited thereby.
As shown in fig. 1, the present invention provides a comprehensive calibration method for an ultrahigh frequency partial discharge sensor, which measures S parameters and effective heights of a tested ultrahigh frequency sensor according to a preset number of scanning points in a preset detection frequency band, and performs multidimensional comprehensive calibration on the return loss, the real bandwidth, the insertion loss, the effective coverage working frequency band, the high gain working frequency band and the real average effective height of the ultrahigh frequency partial discharge sensor by using a detection result and a history value thereof.
It is worth noting that the establishment of the ultrahigh frequency partial discharge sensor inspection and evaluation method system covering the inspection and evaluation dimensions is an important improvement of the invention on the prior art, solves the technical problem that the deep application of the ultrahigh frequency detection technology is limited by relying on a single evaluation effect in the prior art, enriches the evaluation dimensions of the sensor inspection, and realizes the multi-dimensional inspection and effective evaluation on the sensitivity and the omnibearing performance of the sensor.
It will be appreciated that for any dual port, the S parameter describes the response of a signal input to one dual port to each of the ports, as shown in figure 2. Sij means the energy injected from j port and measured at i port. Therefore, for the S parameter of the tested ultrahigh frequency sensor, the return loss size and the real bandwidth of the tested ultrahigh frequency sensor can be verified through the S11 or S22 parameter, and the insertion loss size and the effective coverage working frequency band of two adjacent tested ultrahigh frequency sensors can be verified through the S21 or S12 parameter.
It is understood that any suitable measuring instrument can be used by one skilled in the art to obtain the S-parameters of the vhf sensor under test, and a preferred but non-limiting embodiment is to obtain the S-parameters of the vhf sensor under test using a two-port network analyzer.
Specifically, the comprehensive verification method for the ultrahigh frequency partial discharge sensor comprises the following steps:
The return loss size and the real bandwidth of the tested ultrahigh frequency sensor can be checked through the S11 or S22 parameters, namely the S11 or S22 parameters are smaller than a certain set first threshold value T A The frequency range of (a) is taken as the true bandwidth of the tested uhf sensor. It will be appreciated that T is defined by the line S11 A Intersecting the S11 parametric curve, one or more intersection points may be generated, and the S11 parametric curve is located on the straight line S11 ═ T A At least one frequency range corresponding to the lower part is the real bandwidth of the tested ultrahigh frequency sensor, and an S11 parameter curve and a straight line S11 are T A As a point of intersection ofCorresponding to the cut-off frequency of the real bandwidth frequency range.
As shown in FIG. 3, in one measurement example, a first threshold T is set A Measuring the S11 parameter curve of the tested ultrahigh frequency sensor at-10 dB, intersecting the S11 parameter curve with the straight line S11 at-10 dB, and defining two intersection points as the cut-off frequency of the sensor bandwidth, wherein the lower value is the lower limit cut-off frequency f 1 The higher value is the upper cut-off frequency f 2 If the true bandwidth Δ f of the sensor is f 2 -f 1 。
It is understood that the S22 parametric curve of the vhf sensor under test can be used by those skilled in the art instead of the S11 parametric curve to verify the return loss magnitude and the true bandwidth of the vhf sensor under test.
Similarly, the magnitude of the insertion loss and the effective coverage operating band of two adjacent uhf sensors can be checked by the S21 or S12 parameters, i.e., the S21 or S12 parameters are greater than a certain set second threshold T B As an effective coverage operating band for two adjacent uhf sensors. It will be appreciated that T is the straight line S21 B Intersecting the S21 parametric curve, one or more intersection points may be generated, and the S21 parametric curve is located on the straight line S21 ═ T B At least one frequency range corresponding to the upper part is the working frequency band effectively covered by the tested ultrahigh frequency sensor.
As shown in FIG. 4, in one measurement example, a second threshold T is set B Measuring the S21 parameter curve of the adjacent ultrahigh frequency sensor at-70 dB, and intersecting the S21 parameter curve by using a straight line S21 at-70 dB to obtain three intersection points f 3 、f 4 And f 5 Intersection point f 3 、f 4 And is greater than f 5 The frequency range of (a) is defined as the effective coverage operating band of two adjacent uhf sensors.
It is understood that the S12 parametric curve of two adjacent vhf sensors can be used by those skilled in the art instead of the S21 parametric curve to verify the effective coverage operating band of the two adjacent vhf sensors being tested.
And 2, comparing the S parameter detection result of the tested ultrahigh frequency sensor with the S parameter historical value, and checking the change of the characteristics and the arrangement condition of the sensor.
It can be understood that the S parameter historical value can be obtained by performing a large number of initial return loss characteristic tests on the uhf sensor before the equipment manufacturer leaves a factory, or can be obtained by using the field actual measurement results of other uhf sensors of the same type belonging to the same gas insulated switchgear. In view of the fact that comparison between the current value and the historical value is meaningful when all conditions are consistent, when the settings are the same, for example, but not limited to, the frequency band, the number of sampling points, the degree of smoothness, and the like, the uhf sensor is tested before shipment or the S-parameter historical value is obtained from the on-site actual measurement of other uhf sensors of the same type belonging to the same gas insulated switchgear, and the S-parameter historical value is obtained as the reference value.
The change condition of the return loss can be obtained by comparing the detection results of the S11 or S22 parameters of the tested ultrahigh frequency sensor and analyzing the amplitude difference on each frequency, and the S11 or S22 parameter is smaller than a set first threshold T A The variation of the frequency range of the frequency band obtains the variation condition of the real bandwidth, and the variation condition of each frequency amplitude and the bandwidth is required not to exceed the specified allowable range. One skilled in the art can analyze the variation in any suitable manner, a preferred but non-limiting embodiment being, for example, by performing the calculations with equations (1) and (2) below,
in the formula:
ε return represents the rate of change of the S11 parameter for the vhf sensor under test,
s11 represents the S11 parameter of the vhf sensor under test,
S11 h the historical values of the S11 parameter representing the uhf sensor under test,
ε return0 s11 parameter change representing tested ultrahigh frequency sensorA rate limit value;
in the formula:
ε Δf represents the true bandwidth rate of change of the uhf sensor under test,
af represents the true bandwidth of the uhf sensor under test,
Δf h representing the true bandwidth history of the vhf sensor under test,
ε Δf0 representing the true bandwidth rate limit of the vhf sensor under test.
It is understood that in the above formulas (1) and (2), the S22 parameter of the vhf sensor under test can be used by those skilled in the art instead of the S11 parameter, and can also be used to check the variation of the return loss and the real bandwidth of the vhf sensor under test. Those skilled in the art can also use other calculation methods to calculate the variation of the return loss and the real bandwidth of the ultrahigh frequency sensor under test.
Similarly, the detection results of the parameters S21 or S12 can be compared, the amplitude difference at each frequency can be analyzed to obtain the insertion loss variation, and the S21 or S12 parameter is analyzed to be larger than a set second threshold T B The variation of the effective coverage operating band of two adjacent uhf sensors, required for each frequency amplitude and for the variation of the effective coverage operating band of two adjacent uhf sensors to be less than the specified tolerance range, can be analyzed in any suitable way by the person skilled in the art, a preferred but non-limiting embodiment being, calculated by the following equations (3) and (4) respectively,
in the formula:
ε insertion representing the rate of change of the S21 parameter for two adjacent uhf sensors,
s21 represents the S21 parameters of two adjacent uhf sensors,
S21 h representing the historical values of the S21 parameter for two adjacent uhf sensors,
ε insertion0 a limiting value of S21 parameter change rate representing two adjacent ultrahigh frequency sensors;
in the formula:
ε Δfcover indicating the effective coverage operating band rate of change of two adjacent uhf sensors,
Δf cover representing the effective coverage operating band of two adjacent uhf sensors,
Δf coverh representing the effective coverage operating band history values of two adjacent uhf sensors,
ε Δfcover0 representing the effective coverage operating band change rate limit of two adjacent uhf sensors.
It is understood that in the above formulas (3) and (4), the S12 parameter of two adjacent uhf sensors can be used instead of the S21 parameter by those skilled in the art, and can also be used to check the insertion loss and the variation of the effective coverage operating band of the two adjacent uhf sensors. Those skilled in the art can also use other calculation methods to calculate the variation of the return loss and the real bandwidth of two adjacent uhf sensors.
And 3, measuring the effective height of the sensor according to the scanning points of the preset number in the preset detection frequency band, and checking the current gain performance condition of the sensor.
The effective height H is larger than a set third threshold value T C As the high-gain operating band Δ f of the tested sensor gain And taking the average effective height of the tested sensor in the high-gain working frequency band as the real average effective height
It will be understood that with a straight line H ═ T C Intersecting the effective height curve, one or more intersections may be formed, which are bounded by the intersections, the effective height curve lying on a straight line H ═ T C At least one frequency range corresponding to the upper part is the high-gain working frequency band delta f of the tested ultrahigh frequency sensor gain For high gain operating band Δ f gain Average the effective heights in the inner part, i.e. obtaining the true average effective height
As shown in FIG. 5, in one measurement example, a third threshold T is set C Measuring the effective height curve of the tested ultrahigh frequency sensor (8 mm), intersecting the effective height curve with a straight line H (8 mm), and obtaining two intersection points f 1 And f 2 Then the tested ultrahigh frequency sensor has a high-gain working frequency band delta f gain ＝f 7 -f 6 . For high gain operating band Δ f gain Average the effective heights in the inner part, i.e. obtaining the true average effective height
It should be noted that, a person skilled in the art may arbitrarily set the scanning points in the preset detection frequency band in steps 1 and 3 according to the preset number, and respectively record the real bandwidth, the high-gain working frequency band, and the real average effective height in each working frequency band for the sensor having a plurality of working frequency bands.
It is worth noting that the verification method in the prior art is capable of comprehensively analyzing all parameters in the whole detection frequency range, and is not sufficient in utilization of a large amount of characteristic information, and can cover the problems that the characteristic parameters are unqualified in the frequency division range and the performance of the sensor is poor. As an important improvement of the present invention over the prior art, in the technical scheme of the present invention, the adopted preset detection frequency band may be [300MHz, 3GHz ]; on the basis, a subset in the range of [300MHz, 3GHz ] can be further preferably but not restrictively adopted as a preset detection frequency band; it is further preferred, but not limiting, to divide the subset into a plurality of frequency bands.
As shown in FIG. 6, in one measurement example, [300MHz, 1.5GHz ] is used as a preset detection band on the basis of [300MHz, 3GHz ], and further, [300MHz, 1.5GHz ] is divided into a low frequency subset of [300MHz, 500MHz ], a medium frequency subset of [300MHz, 1.0GHz ] and a high frequency subset of [1.0GHz, 1.5GHz ]. The number of scanning points may be a preset number, which may be determined by a measurement interval, wherein the measurement interval may be a preset interval. Taking the preset frequency band as [300MHz, 1.5GHz ] as an example, if the preset interval is 1MHz, the number of corresponding scanning points may be 1200.
It should be noted that, those skilled in the art may arbitrarily select a suitable preset detection frequency band according to the verification object, where the above-mentioned endpoint, i.e. the division manner, is merely an exemplary but non-limiting implementation manner, and those skilled in the art may use other endpoints to divide the frequency band, and may divide more or fewer frequency bands. The improvement of the invention lies in that the problems of unqualified characteristic parameters and poor sensor performance in partial frequency range are found by checking through reasonably dividing frequency bands, fully utilizing characteristic information, reflecting local information characteristics.
And 4, comparing the effective height detection result of the tested ultrahigh frequency sensor with the historical effective height detection result, and checking the change condition of the gain characteristic of the sensor.
Specifically, the detection results of the effective heights are compared, and the effective heights of the frequencies are analyzed to be larger than a set third threshold value T C The change condition of the high-gain working frequency band is obtained, and the change condition of the average effective height of the tested sensor in the current high-gain working frequency band is analyzed to obtain the change condition of the real average effective height. The high gain operating band and the true average effective height are required to vary less than the prescribed allowable range from their respective historical values, and one skilled in the art can analyze the variation in any suitable manner, as calculated by the following equations (5) and (6),
in the formula:
ε Δfgain indicating the rate of change of the high gain operating band of the uhf sensor under test,
Δf gain representing the high gain operating band of the uhf sensor under test,
Δf gainh representing the high gain operating band history of the uhf sensor under test,
ε Δfgain0 the limiting value represents the high-gain working frequency band change rate of the tested ultrahigh frequency sensor;
in the formula:
It is understood that other calculation methods can be used by those skilled in the art to calculate the variation of the high-gain operating band and the true average effective height of the vhf sensor under test.
As a further preferred embodiment of the present invention, the comprehensive verification method for the uhf partial discharge sensor further includes recording an induced voltage value U between a core wire of the reserved joint and a housing ground wire when the built-in uhf sensor of the operating power transformation device is verified, and comparing the induced voltage value U with a historical value U of the induced voltage value h Comparing, as a reference for checking the characteristic change condition of the tested ultrahigh frequency sensor, and expressing by the following formula,
in the formula:
ε U indicating the rate of change of the induced voltage value,
u represents the value of the induced voltage and,
U h representing a history of values of the induced voltage.
Normally, the voltage should not change significantly, e.g., change significantly, which may be caused by deterioration or damage of the sensor itself or failure of the protection resistor at the joint. If the change is obvious, the inspection of the sensor body and related connecting pieces and protective resistors needs to be paid attention.
It is noted that for the live-line operation equipment, the measurement of the induced voltage value between the core wire of the reserved joint and the shell ground wire should be carried out at the beginning of the verification of the built-in ultrahigh frequency sensor of the transformer equipment in operation. If the induced voltage is too large, the network vector analyzer and other equipment cannot be accessed, so that the equipment is prevented from being damaged. For devices that are not installed or are not operated live, there is no induced voltage and this step is not required.
It is worth noting that as a further improvement of the invention of the method to the prior art, when the current performance state of the sensor is checked, the change situation of the sensor characteristic along with the time dimension and the influence situation of the operating environment are examined through comparing the S parameter detection result, the effective height detection result and the longitudinal history of the induced voltage value between the reserved joint core wire and the shell ground wire.
It can be understood that the verification using the S11 parameter, the S22 parameter, the effective altitude and the induced voltage value is applicable to both the built-in uhf sensor and the external portable uhf sensor, is not limited by the type of the uhf sensor, and is an important improvement of the present invention over the prior art. When the built-in ultrahigh frequency sensor is fixed at the installation position of the GIS and does not change any more, the transmission loss can be accurately represented by using the S21 parameter and the S12 parameter. The above contents show that the verification method provided by the invention has the advantages of wide application range, high verification precision and the like.
The invention also provides a comprehensive verification system of the ultrahigh frequency partial discharge sensor based on the comprehensive verification method, which comprises the following steps: the system comprises a measuring module, a data processing module, a checking and analyzing module and a measuring module, wherein the measuring module is used for measuring S parameters and effective heights of the tested ultrahigh frequency sensor in a preset detection frequency band according to a preset number of scanning points; the data processing module is used for comparing the S parameter detection result of the tested ultrahigh frequency sensor with the S parameter historical value and comparing the effective height detection result of the tested ultrahigh frequency sensor with the effective height historical value; and the checking analysis module is used for checking whether the return loss, the real bandwidth, the insertion loss, the effective coverage working frequency band, the high-gain working frequency band and the real average effective height meet the requirements or not.
The present applicant has described and illustrated embodiments of the present invention in detail with reference to the accompanying drawings, but it should be understood by those skilled in the art that the above embodiments are only preferred embodiments of the present invention, and the detailed description is only for the purpose of helping the reader to better understand the spirit of the present invention, and not for the purpose of limiting the scope of the present invention, and on the contrary, any modifications or modifications based on the spirit of the present invention should fall within the scope of the present invention.
Claims (9)
1. A comprehensive calibration method for an ultrahigh frequency partial discharge sensor is characterized by comprising the following steps:
measuring S parameters and effective heights of the tested ultrahigh frequency sensor according to a preset number of scanning points in a preset detection frequency band, and performing multi-dimensional comprehensive verification on the return loss, the real bandwidth, the insertion loss, the effective coverage working frequency band, the high-gain working frequency band and the real average effective height of the ultrahigh frequency partial discharge sensor by using a detection result and a historical value thereof; the comprehensive verification method comprises the following steps:
step 1, measuring S parameters of a tested ultrahigh frequency sensor, and checking return loss, real bandwidth, insertion loss and effective coverage working frequency band;
step 2, comparing the S parameter detection result of the tested ultrahigh frequency sensor with the S parameter historical value, and checking the change conditions of return loss, real bandwidth, insertion loss and effective coverage working frequency band;
step 3, measuring the effective height of the tested ultrahigh frequency sensor, and checking a high-gain working frequency band and a real average effective height;
and 4, comparing the effective height detection result of the tested ultrahigh frequency sensor with the effective height historical value, and checking the change conditions of the high-gain working frequency band and the real average effective height.
2. The integrated calibration method for UHF partial discharge sensors as claimed in claim 1, wherein:
the step 1 comprises the following steps:
measuring the S11 or S22 parameter curve of the tested ultrahigh frequency sensor, and ensuring that the S11 or S22 parameter is less than a first threshold value T A The frequency range of (A) is used as the true bandwidth of the tested UHF sensor, i.e. the straight line S11 is T A Intersecting the S11 parameter curve, or using the straight line S22 ═ T A Intersecting with the S22 parameter curve, the S11 or S22 parameter curve is T-T at the straight line S11 A Or S22 ═ T A At least one frequency range corresponding to the lower part is the real bandwidth of the tested ultrahigh frequency sensor, and an S11 or S22 parameter curve and a straight line S11 is T A Or S22 ═ T A The intersection point of (a) is taken as the cut-off frequency corresponding to the real bandwidth frequency range;
measuring the S21 or S12 parameter curves of two adjacent ultrahigh frequency sensors, wherein the S21 or S12 parameter is larger than a set second thresholdValue T B As an effective coverage operating band for two adjacent uhf sensors, i.e. using the straight line S21 ═ T B Intersecting the S21 parameter curve, or using the straight line S12 ═ T B Intersecting with the S12 parameter curve, the S21 or S12 parameter curve is T-T at the straight line S21 B Or S12 ═ T B At least one frequency range corresponding to the upper part is an effective coverage working frequency band.
3. The comprehensive verification method for the UHF partial discharge sensor as claimed in claim 2, wherein:
the step 2 comprises the following steps:
comparing the detection results of the S11 or S22 parameters, analyzing the amplitude difference on each frequency to obtain the change condition of the return loss, and analyzing that the S11 or S22 parameter is smaller than a first threshold value T A The change condition of the real bandwidth of the sensor is obtained, and the change condition of each frequency amplitude and the bandwidth which are respectively compared with the respective historical values is required to be smaller than the specified allowable range.
4. A comprehensive verification method for uhf partial discharge sensors, according to claim 2 or 3, characterized in that:
the step 2 comprises the following steps:
comparing the detection results of the S21 or S12 parameters, analyzing the amplitude difference on each frequency to obtain the change condition of the insertion loss, and analyzing whether the S21 or S12 parameter is larger than a certain second threshold value T B The variation condition of the effective coverage working frequency bands of the two adjacent ultrahigh frequency sensors is obtained, and the variation condition of each frequency amplitude and the effective coverage working frequency bands of the two adjacent ultrahigh frequency sensors is required to be smaller than a specified allowable range compared with each historical value.
5. The integrated calibration method for UHF partial discharge sensors as claimed in any one of claims 1 to 4, wherein:
the step 3 comprises the following steps:
with the effective height being greater than a third threshold value T C As a sensor under testHigh gain working frequency band, and using the average effective height of the tested sensor in the high gain working frequency band as the real average effective height, i.e. using the straight line H ═ T C Intersecting the effective height curve, one or more intersections may be formed, which are bounded by the intersections, the effective height curve lying on a straight line H ═ T C At least one frequency range corresponding to the upper part is the high-gain working frequency band delta f of the tested ultrahigh frequency sensor gain For high gain operating band Δ f gain Average the effective heights in the inner part, i.e. obtaining the true average effective height
6. The integrated calibration method for UHF partial discharge sensors as claimed in any one of claims 2 to 5, wherein:
step 4 comprises the following steps:
comparing the detection results of the effective heights, and analyzing that the effective heights at all frequencies are greater than a third threshold value T C Obtaining the change condition of the high-gain working frequency band according to the change condition of the frequency range, and analyzing the change condition of the average effective height of the tested sensor in the current high-gain working frequency band to obtain the change condition of the real average effective height; the variation of the high-gain operating frequency band and the actual average effective height compared with the respective historical values is required to be less than the specified allowable range.
7. The comprehensive verification method for UHF partial discharge sensors as claimed in any one of claims 2 to 6, wherein:
the adopted preset detection frequency band can be [300MHz, 3GHz ]; or
A subset in the range of [300MHz and 3GHz ] is adopted as a preset detection frequency band; or
And (3) adopting the subset in the range of [300MHz and 3GHz ] as a preset detection frequency band and dividing the subset into a plurality of frequency bands for verification respectively.
8. The comprehensive verification method for the UHF partial discharge sensor according to any one of claims 2 to 7, wherein:
further comprising:
when the built-in ultrahigh frequency sensor of the power transformation equipment in operation is checked, the induced voltage value between the core wire of the reserved joint and the shell ground wire is recorded and compared with the historical result to be used as a reference for checking the characteristic change condition of the tested ultrahigh frequency sensor.
9. An integrated calibration system of a uhf partial discharge sensor based on the integrated calibration method of any one of claims 1 to 8, comprising: a measuring module, a data processing module and a checking and analyzing module, which are characterized in that,
the measuring module is used for measuring S parameters and effective heights of the tested ultrahigh frequency sensor according to a preset number of scanning points in a preset detection frequency band;
the data processing module is used for comparing the S parameter detection result of the tested ultrahigh frequency sensor with the S parameter historical value and comparing the effective height detection result of the tested ultrahigh frequency sensor with the effective height historical value;
and the checking analysis module is used for checking whether the return loss, the real bandwidth, the insertion loss, the effective coverage working frequency band, the high-gain working frequency band and the real average effective height meet the requirements or not.
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