CN112345966B - Method and device for detecting direct current leakage through residual current transformer - Google Patents
Method and device for detecting direct current leakage through residual current transformer Download PDFInfo
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Abstract
The invention relates to a method and a device for detecting direct current leakage through a residual current transformer. Because the direct current leakage signal does not fluctuate, an external magnetic field is needed, the invention uses the singlechip to output controllable square waves to realize the external magnetic field, so that the magnetic flux of the coil at the current moment reaches a saturation region, and the magnitude of the current direct current leakage value is reversely deduced according to the difference of numerical values fed back by the saturation region; the external magnetic field can be maintained unchanged after saturation is achieved, the changing magnetic flux approaches to be stable after the magnetic induction intensity B of the secondary coil is unchanged, and the magnitude of the current direct current leakage value is reversely deduced according to the changing characteristic of the secondary induction voltage; or after the coil reaches the saturation region and the voltage is not stable, applying a reverse magnetic field to enable the coil to reach the saturation region of the other phase, and repeating the steps, so that the current direct current leakage value can be reversely deduced according to the magnetic induction intensity values of different saturation regions of the coil caused by different direct current leakage, and the direct current leakage detection and corresponding protection are carried out.
Description
Technical Field
The invention belongs to the field of direct current leakage detection, and mainly relates to a method and a device for detecting direct current leakage through a residual current transformer.
Background
Along with economic development, the power consumption demand is increased day by day, so that the power industry develops rapidly, the scales of various household appliances are enriched day by day, and how to ensure the power consumption safety of residents becomes more important, especially for the problem of direct current leakage, the current direct current is widely applied, including direct current charging piles, variable frequency motors and the like, and the household appliances such as certain types of notebooks, microwave ovens, washing machines and the like. With the increasing abundance of types of electrical appliances, the probability of direct current leakage possibly caused in a circuit is increased day by day, and the direct current leakage is caused by a plurality of reasons, such as unqualified secondary circuit insulating materials, or long-term failure, severe aging, equipment damage defects, damp secondary circuits and equipment, water inflow and the like. The direct current system is also a main reason for generating direct current leakage, and is generally applied to places such as water conservancy plants, thermal power plants, various transformer substations and the like.
At present, there are many direct current detection methods, and the development of direct current detection technology is gradually improved, and according to the existing device and detection method, the method can be divided into: direct current bridge method, signal injection method, and differential current detection method: the direct current bridge method is earlier applied to direct current detection, but the method has larger error; the differential current detection method is to detect the difference value of the current flowing in and out of a certain branch conductor by using a high-sensitivity non-contact direct current sensor to judge the insulation condition of the branch load. The signal injection method is to detect an alternating current of a specific frequency injected into a direct current operating power supply.
The invention combines the advantages of a differential current detection method and a signal injection method, uses a residual current transformer as a detection element, and the center of a coil passes through L/N two lines to detect the direct current leakage value at the moment through the imbalance of the current flowing in and the current flowing out. As is known, direct current cannot enable a coil to generate a magnetic field, namely a transformer cannot detect a direct current leakage value in a line, at the moment, a single chip microcomputer is used for generating positive and negative two-phase square waves by means of the idea of a signal injection method, and the frequency and the amplitude are controllable. The suddenly added square wave signal is input from the primary side of the transformer, an instantaneous magnetic field can be generated in the coil, the secondary side winding of the residual current transformer can induce the magnetic field, and therefore a corresponding electric signal is output.
Disclosure of Invention
The invention relates to a method and a device for detecting direct current leakage through a residual current transformer. And performing direct current leakage test by detecting residual current in the circuit, calculating a direct current leakage value by secondary algorithm analysis, and protecting the circuit in time.
The invention uses the residual current transformer of the two-phase coil as the detection device, as shown in figure 1, different square waves can be output through the pins of the control chip, and different square wave amplitudes can generate different magnetic field strengths because the rising edges of the square waves are instantaneous by default. After being output from a chip pin, the square wave is input to an i1 port of the current transformer, a primary side winding generates a magnetic field, the magnetic field exists through magnetic lines, a secondary side winding generates induction to the transient magnetic field so as to generate corresponding current, the current is read by an ADC (analog to digital converter) sampling module through a sampling resistor and then is input to an algorithm module for analysis, and corresponding action is executed according to the result;
the single chip microcomputer generates square waves (F1 > F2) with fixed frequencies of F1 and F2, the high-frequency characteristic utilizes the characteristic that different leakage values of a hysteresis loop of permalloy reach different saturation regions, the low-frequency characteristic also utilizes the characteristic that secondary induction voltage is stable after the amplitude of an excitation square wave of the permalloy is constant, and the current value of direct current leakage is reversely deduced according to different sampling curve characteristics generated by different characteristics;
by utilizing the hysteresis loop characteristics of permalloy, when the frequency F1 is used, the secondary winding induces a magnetic field generated by the primary winding (the magnetic field is superposed with a direct current leakage component), due to the transient change of the square wave, the transient magnetic field generated by the square wave can enable the secondary winding to reach a magnetic saturation region, meanwhile, the reversed square wave is immediately applied, the reversed magnetic field with the same size is generated, at the moment, the secondary winding changes from the magnetic saturation region at one side to the magnetic saturation region at the other side, and different direct current leakage values enable the magnetic induction intensity of the magnetic saturation region reached by the secondary winding to reach
B is different, so that corresponding direct current leakage values are obtained by extracting and analyzing different magnetic induction intensities;
by utilizing the hysteresis loop characteristics of permalloy, when the frequency F2 is used, the secondary winding induces a magnetic field generated by the primary winding (the magnetic field is superposed with a direct current leakage component), the transient magnetic field generated by the square wave is considered to be a transient magnetic field, the secondary winding can reach a magnetic saturation region, and at the moment, the effect is different from the effect of the frequency F1, a reverse magnetic field is immediately applied to the square wave, the output of the square wave is continuously kept unchanged, namely the magnetic field does not interfere with the secondary winding, and the process of stabilizing the magnetic flux change is utilized, the induced voltage of the secondary winding at the moment is gradually reduced, different reduction speeds correspond to different leakage values, and the data analysis sampling values are different, so that the corresponding direct current leakage values are obtained.
Drawings
Fig. 1 is a schematic diagram of the operating principle of a residual current transformer.
Fig. 2 is a simplified model schematic of a detection device.
Fig. 3 is a schematic diagram of feature quantity extraction of square waves of different frequencies.
FIG. 4 is a simplified model schematic of the hysteresis loop for permalloy.
Fig. 5 is a graph of the effect of using a low frequency square wave for dc leakage.
Fig. 6 is a graph of the effect of using a high frequency square wave for dc leakage.
Detailed Description
The following describes a method and an apparatus for dc leakage testing using a residual current transformer proposed in the present invention with reference to fig. 1 to 4.
The invention uses the residual current transformer of the two-phase coil as the detection device, the alternating magnetic field is generated by the square wave output by the constant current source generated by the chip pin, and different square wave amplitudes can generate different magnetic field strengths. As shown in fig. 1, after the square wave is output from the chip pin, it is input to the i1 port of the current transformer, and the primary winding generates a magnetic field, if a dc leakage current occurs in the LN line at this time, according to the ampere loop theorem,
H*l＝N*i(t) (1)
thus, according to the simplified model of fig. 2, one can obtain:
H*l＝N 3 *i p +i 1 *N 1 ＝i 2 *N 2 (2)
is represented by the formula (2), wherein N 3 For 1 turn, one can obtain:
when there is DC leakage i p When i is p Is actually equivalent to making i 1 Move i p /N 1 。
At this time, the secondary side winding induces a changing magnetic field and dc leakage, according to the simplified model of fig. 2, the loop equation of the secondary side:
by
B(t)＝μ 0 *μ(j)*H(t) (6)
Substituting into formula (4), we can get:
since i (p) is direct current, equation (7) can be simplified as:
the secondary side generates corresponding induced current i 2 The sampling resistor is read by the ADC acquisition module and then input into the algorithm unit for analysis;
the single chip microcomputer generates square waves (F1 > F2) with fixed frequencies of F1 and F2, the high-frequency characteristic utilizes different leakage values of hysteresis loops of permalloy to achieve the characteristic of different saturation regions, the low-frequency characteristic keeps the output of the square waves unchanged, namely, the magnetic field does not interfere with a secondary side winding, and by utilizing the process of stable magnetic flux change, the induced voltage of the secondary side winding at the moment is stable, different stable speeds correspond to different leakage values, and data analysis sampling values are different, so that corresponding direct current leakage values are obtained;
by utilizing the hysteresis loop characteristics of permalloy, as shown in fig. 3 (left), when the frequency F1 is used, the secondary winding induces a magnetic field generated from the primary winding (the magnetic field is superposed with a direct current leakage component), the transient magnetic field generated by the square wave is considered to enable the secondary winding to reach a magnetic saturation region due to the instantaneous change of the square wave, meanwhile, the reversed square wave is immediately applied, namely, a reversed magnetic field with the same size is generated, at the moment, the secondary winding changes from the magnetic saturation region on one side to the magnetic saturation region on the other side, and the magnetic induction strength B of the magnetic saturation region reached by the secondary winding is different due to different direct current leakage values, so that the corresponding direct current leakage values are obtained by extracting and analyzing different magnetic induction strengths;
by utilizing the hysteresis loop characteristics of permalloy, as shown in fig. 3 (right), when the frequency F2 is used, the secondary winding induces a magnetic field (the magnetic field is superposed with a direct current leakage component) generated from the primary winding, and the transient magnetic field generated by the square wave is considered to reach a magnetic saturation region, and at the moment, the effect is different from that of the frequency F1, a reverse magnetic field is immediately applied to the square wave, but the output of the square wave is continuously kept unchanged, namely, the magnetic field does not interfere with the secondary winding, and by utilizing the process of stable magnetic flux change, the induced voltage of the secondary winding at the moment is gradually reduced, different reduction speeds correspond to different leakage values, and different data analysis sampling values are obtained, so that corresponding direct current leakage values are obtained.
The magnetic hysteresis loop of permalloy is combined with the frequency of different square waves, different effects can be achieved, the low frequency utilizes the characteristic that the magnetic flux change in the secondary coil is stabilized towards 0, the proper stabilization time is selected, and the high frequency utilizes the characteristic of the saturation region of the magnetic hysteresis loop to select the proper excitation time to reach the magnetic induction intensity value in the saturation region. The following tables I, II and III are respectively the data verification of a plurality of time lengths corresponding to the two principles:
the method comprises the following steps: controlling the single chip microcomputer to generate square waves with the frequency of F1, operating the ADC for data acquisition with one cycle of time, and sending the data to the single chip microcomputer;
controlling the single chip microcomputer to generate square waves with the frequency of F2, operating the ADC for data acquisition with the time of one cycle, and sending the data to the single chip microcomputer;
step two: carrying out data extreme value taking and slope operation on data using square wave frequency F1, bringing the extreme value and the slope into an equation according to a curve calculated by the previously fitted direct current leakage value about the F1 square wave, reversely deducing a direct current leakage value corresponding to the extreme value, and sending a result into a logic control module of a singlechip;
carrying out data extreme value obtaining operation on data using square wave frequency F2, obtaining a certain proportion of data points for next processing according to the positions of the extreme points, carrying out mean value filtering on the selected data points, then carrying out slope calculation operation on the filtered data, then accumulating all slopes to form characteristic quantity output, substituting the characteristic quantity into an equation according to a curve calculated by the previously fitted direct current leakage value relative to the characteristic quantity generated by the F2 square wave, reversely deducing the direct current leakage value corresponding to the characteristic quantity, and sending the result to a logic control module of a single chip microcomputer;
for data using square wave frequency F2, on the basis of 0mA data, euclidean distance processing is carried out on curves of different direct current leakage values and 0mA to obtain a characteristic curve, then during actual measurement, euclidean distance processing is carried out on a measured value and a prestored 0mA curve, the result is compared with the previous characteristic curve to reversely deduce the actual leakage value, and the result is sent to a logic control module of a single chip microcomputer;
step three: analyzing the results of the two logic modules and outputting a final result; whether the direct current leakage condition exists or not, the step I is skipped back to continue to judge next time, and corresponding actions can be executed if the requirements of the logic module of the single chip microcomputer are met.
Fig. 5 and 6 are diagrams of the effect of using low-frequency and high-frequency square waves for dc leakage, respectively, and the dc leakage value is selected from 0mA to 100mA, and every 20mA interval, respectively, and from the results in the diagrams, it can be seen that the actual effect is the same as the theoretical derivation.
The foregoing is only a preferred embodiment of this invention and modifications and variations such as will be apparent to those skilled in the art may be made without departing from the principles of the invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection of the present invention.
Claims (4)
1. The invention relates to a detection method for detecting direct current leakage through a residual current transformer, which is characterized by comprising the following steps of:
performing direct current leakage test by detecting residual current in the circuit, calculating a direct current leakage value by secondary algorithm analysis, and protecting the circuit in time; because the direct current leakage signal does not fluctuate, a magnetic field needs to be added, namely a single chip microcomputer is used for controlling the output square wave to enable the magnetic flux of the coil at the current moment to reach a saturation region, and the data is sent to an algorithm module through a sampling circuit for analysis; reversely deducing the magnitude of the current direct current leakage value according to the difference of the values fed back by the saturation region; the external magnetic field can be maintained unchanged after saturation is reached, the induction voltage of the secondary coil tends to 0 because the magnetic induction intensity B tends to be stable, and the magnitude of the current direct current leakage value can be reversely deduced according to the characteristic that the voltage stabilizing process reaches 0; executing corresponding logic according to the measured current direct current electric leakage value;
by utilizing the secondary voltage stability characteristic, when the square wave frequency is F2, the data is processed in the half wave based on F2: removing the fluctuation of sampling points by using mean filtering to enable the data to be smoother, then solving the change rate of the data at fixed time intervals, and finally summing all the change rates in the half waves; selecting a 0mA direct current leakage waveform as a reference, solving Euclidean distances from different leakage values and the reference, and using a matrix of the Euclidean distances formed by a series of leakage values as a characteristic quantity table look-up matrix;
by utilizing the characteristic of the saturation region, when the square wave frequency is F1, the data is processed in the half wave based on the F1: and searching the maximum value of the half-wave and the fastest change rate of the data in the half-wave in a certain time as characteristic quantities to form a coefficient matrix, and using the coefficient matrix formed by a series of leakage values as a characteristic quantity lookup matrix.
2. The method for detecting direct current leakage through the residual current transformer according to claim 1, wherein the method comprises the following steps: the residual current transformer using the two-phase coil is used as a detection device, an alternating magnetic field is generated through a square wave output by a constant current source generated by a chip pin, different square wave amplitudes can generate different magnetic field strengths, the square wave is output from the chip pin and then input into a current transformer port, a primary side winding generates a magnetic field, if a direct current leakage current occurs at the moment, a secondary side winding induces a changed magnetic field and the direct current leakage current, so that a corresponding current is generated, and the current is input into a single chip microcomputer for analysis after being read by an ADC (analog to digital converter) through a sampling resistor.
3. The method for detecting direct current leakage through a residual current transformer according to claim 1, wherein the method comprises the following steps: the single chip microcomputer generates square waves (F1 > F2) with fixed frequencies of F1 and F2, the high-frequency characteristic utilizes the characteristic that different leakage values of a hysteresis loop of permalloy reach different saturation regions, the low-frequency characteristic also utilizes the characteristic that after the saturation region of the hysteresis loop of the permalloy, the amplitude of the square waves is maintained, the induced voltage of a secondary coil tends to be stable, when the permalloy reaches magnetic saturation, a reverse magnetic field is not applied immediately, but the magnetic field in the coil is stable, the constant magnetic induction intensity corresponds to the constant magnetic flux, and the current value of direct current leakage is reversely deduced according to different secondary induced voltage curve characteristics.
4. The method for detecting direct current leakage through the residual current transformer according to claim 1, wherein the method comprises the following steps: by utilizing the hysteresis loop characteristics of permalloy, when the frequency F1 is used, the secondary side winding induces a magnetic field generated by the primary side winding (the magnetic field is superposed with a direct current leakage component), the transient magnetic field generated by the square wave is considered to enable the secondary side winding to reach a magnetic saturation region due to the instantaneous change of the square wave, meanwhile, the reversed square wave is immediately applied, namely, the reversed magnetic field with the same size is generated, at the moment, the secondary side winding changes from the magnetic saturation region at one side to the magnetic saturation region at the other side, the magnetic induction strengths B of the magnetic saturation regions reached by the secondary side winding are different due to different direct current leakage values, and the corresponding direct current leakage values are obtained by extracting and analyzing the different magnetic induction strengths;
by utilizing the hysteresis loop characteristics of permalloy, when the frequency F2 is used, the secondary winding induces a magnetic field generated by the primary winding (the magnetic field is superposed with a direct current leakage component), the transient magnetic field generated by the square wave is considered to be a transient magnetic field, the secondary winding can reach a magnetic saturation region, and at the moment, the effect is different from the effect of the frequency F1, a reverse magnetic field is immediately applied to the square wave, the output of the square wave is continuously kept unchanged, namely the magnetic field does not interfere with the secondary winding, and the process of stabilizing the magnetic flux change is utilized, the induced voltage of the secondary winding at the moment is gradually reduced, different reduction speeds correspond to different leakage values, and the data analysis sampling values are different, so that the corresponding direct current leakage values are obtained.
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Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9408894D0 (en) * | 1994-05-05 | 1994-06-22 | Secr Defence | Electronic circuit |
| CN1892241A (en) * | 2005-07-08 | 2007-01-10 | 河海大学常州校区 | Circuit device of leakage current detector of lightning protector and its operating method |
| CN101923134A (en) * | 2010-03-22 | 2010-12-22 | 许继集团有限公司 | Digital leakage current detection circuit and detection method thereof |
| CN103675396A (en) * | 2012-09-13 | 2014-03-26 | 武汉金天新能源科技有限公司 | Leak current detector for photovoltaic inverter |
| CN104931758A (en) * | 2014-03-21 | 2015-09-23 | 上海电科电器科技有限公司 | Direct-current residual current detection apparatus |
| JP2016031253A (en) * | 2014-07-28 | 2016-03-07 | 光商工株式会社 | Dc leakage current detection device |
| CN107342578A (en) * | 2016-04-28 | 2017-11-10 | Ls 产电株式会社 | Tripping operation control circuit for breaker |
| CN206832877U (en) * | 2017-04-25 | 2018-01-02 | 中国石油天然气股份有限公司 | Device for detecting leakage current, transmitter, sensor and automatic control system |
| CN208172089U (en) * | 2018-04-08 | 2018-11-30 | 江阴市星火电子科技有限公司 | A kind of sensor for DC leakage current detection |
| CN109406932A (en) * | 2018-11-02 | 2019-03-01 | 罗孚电气（厦门）有限公司 | Earth detector and system |
| CN109742727A (en) * | 2018-12-21 | 2019-05-10 | 国网湖南省电力有限公司 | A kind of judgment method of low pressure 400V leakage current |
-
2019
- 2019-08-07 CN CN201910723872.3A patent/CN112345966B/en active Active
Patent Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9408894D0 (en) * | 1994-05-05 | 1994-06-22 | Secr Defence | Electronic circuit |
| CN1892241A (en) * | 2005-07-08 | 2007-01-10 | 河海大学常州校区 | Circuit device of leakage current detector of lightning protector and its operating method |
| CN101923134A (en) * | 2010-03-22 | 2010-12-22 | 许继集团有限公司 | Digital leakage current detection circuit and detection method thereof |
| CN103675396A (en) * | 2012-09-13 | 2014-03-26 | 武汉金天新能源科技有限公司 | Leak current detector for photovoltaic inverter |
| CN104931758A (en) * | 2014-03-21 | 2015-09-23 | 上海电科电器科技有限公司 | Direct-current residual current detection apparatus |
| JP2016031253A (en) * | 2014-07-28 | 2016-03-07 | 光商工株式会社 | Dc leakage current detection device |
| CN107342578A (en) * | 2016-04-28 | 2017-11-10 | Ls 产电株式会社 | Tripping operation control circuit for breaker |
| CN206832877U (en) * | 2017-04-25 | 2018-01-02 | 中国石油天然气股份有限公司 | Device for detecting leakage current, transmitter, sensor and automatic control system |
| CN208172089U (en) * | 2018-04-08 | 2018-11-30 | 江阴市星火电子科技有限公司 | A kind of sensor for DC leakage current detection |
| CN109406932A (en) * | 2018-11-02 | 2019-03-01 | 罗孚电气（厦门）有限公司 | Earth detector and system |
| CN109742727A (en) * | 2018-12-21 | 2019-05-10 | 国网湖南省电力有限公司 | A kind of judgment method of low pressure 400V leakage current |
Non-Patent Citations (3)
| Title |
|---|
| 《基于单磁芯结构的磁调制式直流漏电流互感器》;丁扣祥等;《信息技术》;20141231(第3期);第131-136页 * |
| 《复杂波形剩余电流综合保护器的设计与研究》;张军伟;《中国优秀博硕士学位论文全文数据库(硕士)信息科技辑》;20130615;第8-14页 * |
| 《磁调制式剩余电流传感器的动态励磁过程分析与仿真》;武一等;《电工技术学报》;20140731;第29卷(第7期);第244-252页 * |
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