CN110231539B - Single-pole ground fault detection system for true bipolar direct current transmission and distribution line - Google Patents
Single-pole ground fault detection system for true bipolar direct current transmission and distribution line Download PDFInfo
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- G01—MEASURING; TESTING
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- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0046—Arrangements for measuring currents or voltages or for indicating presence or sign thereof characterised by a specific application or detail not covered by any other subgroup of G01R19/00
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
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Abstract
The invention discloses a single-pole ground fault detection system for a true bipolar direct current transmission and distribution line, which is characterized in that in the single-pole ground fault detection of the true bipolar direct current transmission and distribution line, the magnitude of ground fault current and a ground pole are judged according to magnetic flux phi sensed by a magnetic ring in a measuring system, and the position of ground fault occurrence is judged through a plurality of measuring systems arranged on a direct current side line, so that the ground fault can be quickly and effectively searched and eliminated. Therefore, the invention provides a single-pole ground fault detection system for a true bipolar direct current power transmission and distribution line, which is suitable for engineering practice.
Description
Technical Field
The invention belongs to the field of electrical engineering, instrument science and technology, and particularly relates to a single-pole ground fault detection system for a true bipolar direct current transmission and distribution line.
Background
The DC power transmission and distribution system mainly comprises an AC system, a converter station and a DC power transmission line. The converter station is the most important part in the direct current transmission and distribution system, and the current common electrical main wiring schemes of the direct current converter station mainly comprise a unipolar symmetrical wiring scheme and a bipolar symmetrical wiring scheme. The unipolar symmetrical wiring is also called pseudo-bipolar, is the most common wiring scheme of the current direct current power transmission and distribution system, adopts a proper grounding device to clamp the neutral point potential on the alternating current side or the direct current side, and is suitable for cable lines with low probability of short-circuit faults. The bipolar symmetrical wiring is also called as a true bipolar, the unilateral converter station is composed of an upper converter and a lower converter with the same structure, the upper converter and the lower converter respectively form a positive pole and a negative pole, the two poles can independently operate, and a return current path is formed by using a metal return line or a grounding pole. When the true bipolar direct current transmission and distribution system has a unipolar ground fault, the non-fault electrode is not affected by the fault electrode, and compared with a pseudo bipolar system, the true bipolar system has half lower wiring insulation level and is easy for staged construction and capacity increase construction of the whole direct current system.
The true bipolar wiring mode has multiple operation modes, and is mainly divided into two modes according to the grounding mode. One is bipolar double-end grounding operation without a metal return line, in the operation mode, neutral wires of converter stations at two sides are respectively grounded in stations, the ground is used as a current return line, and two-stage unbalanced current returns through the ground; however, the operation mode can not be operated for a long time, the bipolar current balance needs to be ensured during the operation, and the unbalanced current can not exceed a set value (generally 100A). The other type is that the bipolar belt metal return line is operated in a single-end grounding mode, the metal return line is grounded at a single point of a converter station at one end, and the grounding point only plays a role in clamping the potential and does not provide a direct current path. In the grounding mode, bipolar balanced operation is generally adopted, namely, the voltages and currents of the positive electrode and the negative electrode are equal in magnitude and opposite in direction; when there is a bipolar imbalance current, the imbalance current will return through the metal return.
The true bipolar direct current transmission and distribution system generally operates in a mode of single-ended grounding of a bipolar metal return line, and the true bipolar system has a fault isolation effect on a direct current side unipolar grounding fault, so that a fault pole stops operating and the grounding voltage is reduced to zero when the direct current side unipolar grounding fault occurs, while a non-fault pole can normally operate for a long time and a bus is unchanged in the grounding voltage, namely the bipolar operation is changed into the unipolar operation, and the metal return line reduces the influence of return current of the unipolar operation. However, the load borne by the non-fault electrode is increased, and the loss of power components is easily caused by a large load current; and in the case of a single-point ground fault, if a second point or multiple points are grounded, whether in a fault pole or not, protection, switch malfunction or failure of the direct current system can be caused, and in a serious case, the direct current system can be crashed. Therefore, when a single-pole ground fault occurs in a direct-current side line of a direct-current power transmission and distribution system, a fault point still needs to be quickly found and the single-pole ground fault needs to be eliminated.
In summary, no matter a true bipolar dc power transmission and distribution system with bipolar without metal return line operating at both ends or with bipolar with metal return line operating at single-end ground is adopted, when a unipolar ground fault occurs in a dc side line of the system, it is necessary to identify a fault pole and a fault section as soon as possible so as to quickly find and eliminate the fault.
Disclosure of Invention
The invention aims to provide a single-pole ground fault detection system suitable for engineering practice and used for a true bipolar direct current power transmission and distribution line.
The invention is realized by adopting the following technical scheme:
a single-pole ground fault detection system for a true bipolar direct current transmission and distribution line is composed of a plurality of measurement systems for monitoring the current of the direct current transmission line, wherein each measurement system comprises a magnetic ring for measuring the direct current, a related magnetic measurement element, a conditioning circuit, a signal acquisition and processing circuit and a communication circuit; wherein the content of the first and second substances,
the magnetic measurement element is used for indirectly obtaining magnetic flux representing a direct current line current difference value in the magnetic ring, the conditioning circuit conditions a signal output by the magnetic measurement element to a recognizable range of the signal acquisition and processing circuit, the signal processing circuit obtains a line ground fault pole and a fault current value through analysis, and the communication circuit is used for data transmission and networking; when the device is used, a set of measuring system is installed on a direct current side circuit of the true bipolar direct current transmission and distribution system at intervals of a set distance, and when the positive pole or the negative pole of the direct current side has an earth fault, the magnitude of the fault current, the fault pole and the fault position of the true bipolar unipolar earth fault are judged according to the result measured by the measuring device.
The invention has the further improvement that a magnetic ring in the measuring system is arranged on a positive and negative circuit on the direct current side, positive and negative power transmission lines pass through the magnetic ring once and the two power transmission lines are positioned on the same diameter of the magnetic ring; the magnetic flux in the magnetic ring can be measured in any mode, the magnetic measuring element is arranged on a reserved air gap of the magnetic ring, and the length l of the air gapgUnder the condition of satisfying the installation condition of the magnetic measuring element, the magnetic induction intensity in the air gap is ensured to be vertical to the magnetic measuring element as small as possible, so that the sectional area S of the magnetic ring satisfies the requirement
lg/S<α (1)
Alpha in the formula is selected to be between 2 percent and 5 percent, and simultaneously, the selected magnetic ring satisfies l/(mu)0μr)<<lg/μ0Time, air gap length lgDetermined according to equation (2)
lg＝IFm×μ0/Bm (2)
In the formula IFmRepresents the maximum allowable ground fault current, l represents the average magnetic path length of the magnetic loop, mu0Denotes air permeability, μrRepresenting the relative permeability of the material of the magnetic ring, BmAnd (4) representing the maximum magnetic flux density change value of the magnetic ring material, and comprehensively selecting a proper magnetic ring according to the requirements.
The invention is further improved in that a signal conditioning circuit in the measuring system processes the signal from the magnetic measuring element, the actual effective resolution of the signal acquisition circuit is not less than 12 bits, and the corresponding microprocessor has predetermined processing and response speeds, meets the requirements of the response time of the measuring device and is matched with the speed of the signal acquisition circuit.
The invention has the further improvement that magnetic flux phi related to the earth fault current is induced in a magnetic ring in the measuring system, when a true bipolar direct current power transmission and distribution system normally works, the bipolar of the true bipolar direct current power transmission and distribution system runs in a balanced mode, namely, the current flowing through the positive and negative power transmission lines is consistent in magnitude and opposite in direction, the earth fault current does not exist, and the magnetic flux phi on the magnetic ring is 0; when a single-pole earth fault occurs on the direct current side, the current flowing in the positive and negative lines on the direct current side is not consistent any more, namely, the earth fault current I exists at the fault pointFSuppose that the ground fault has phi at the time of occurrence of the positive pole>0, then the earth fault occurs at the negative pole with phi<0。
A further improvement of the invention is that the induced magnetic flux phi in the magnetic loop of the measurement system is proportional to the earth fault current IFI.e. with phi ═ kxIFCalculating the fault current I from the measured magnetic fluxFThe size of (d); the coefficient k passes the test standard current IF0The corresponding induced magnetic flux phi0Is obtained by
k＝φ0/IF0 (3)
The invention is further improved in that when a plurality of measurement systems are arranged on the direct current side circuit of the true bipolar direct current power transmission and distribution system, the magnetic flux phi measured by a plurality of measurement points is obtained1、φ2、…、φnIf the magnetic flux measured at the a-th and b-th measuring points closest to each other is phiaAnd phibIf one absolute value is maximum and the other absolute value is minimum, the monopolar earth fault occurring section is between the two measuring points; if the two measurement points are numbered with b>a +1, the possible failure of the measurement system between the two measurement points is simultaneously shown, and when the single-pole ground fault in the section is checked, the possible failure measurement system needs to be checked.
The invention further improves that the position of the unipolar earth fault point of the true bipolar direct current transmission and distribution system is obtained as follows:
according to the characteristic that the true bipolar line has current transient when the unipolar earth fault occurs, the distance L of three measurement points including the a-th measurement point, the b-th measurement point and the adjacent measurement point of one of the two measurement points in the section where the fault point is located is obtained by the method in claim 6ab、LcaMeasuring the transient time difference to judge the position of the fault point, wherein the sequence of the measurement points is assumed to be c, a and b; assuming that a certain moment before the fault is a zero moment, the time for measuring the transient by the three measuring points is ta、tbAnd tcThe distance of the faulty point from the a-th and b-th measuring points is respectively
s1＝(Lab+β×Lca)/2 (8)
s2＝(Lab-β×Lca)/2 (9)
Wherein β ═ ta-tb)/(tc-ta) If the sequence of the measuring points is a, b and c, and so on.
The invention has at least the following beneficial technical effects:
in the detection of the single-pole ground fault of the true bipolar direct current power transmission and distribution system, the magnitude of the ground fault current and the grounding pole are judged according to the magnetic flux phi sensed by the magnetic ring in the measuring system, and the position of the ground fault is judged through the measuring systems arranged on the direct current side circuit, so that the ground fault can be quickly and effectively searched and eliminated. The invention provides a single-pole ground fault detection system suitable for engineering practice and used for a true bipolar direct current transmission and distribution line.
Drawings
FIG. 1 is a schematic diagram of a wiring mode operation topology of a true bipolar DC transmission and distribution system, and FIG. 1(a) shows bipolar double-ended ground operation without metal return lines; FIG. 1(b) shows bipolar strap metal return line single ended ground operation.
Fig. 2 is a schematic diagram of a measurement system structure for detecting a single-pole ground fault of a true bipolar direct-current transmission and distribution line and a connection mode thereof.
Fig. 3 is a schematic diagram of the true bipolar dc side line unipolar ground fault location principle.
Detailed Description
The invention will be further illustrated and discussed in connection with the figures and examples.
A true bipolar direct current transmission and distribution system generally operates for a long time according to fig. 1(b) by adopting single-end grounding of a bipolar metal return line, and when the bipolar is unbalanced, unbalanced current returns through the metal return line; sometimes the metal return line can be cut off, according to fig. 1(a), a bipolar operation without metal return line is used with double-ended grounding, but it must not be operated in this manner for a long time and the unbalanced current must not exceed a set value during operation. No matter which mode of the two connection modes of fig. 1 is operated, when a unipolar ground fault occurs on a dc-side line of a true bipolar dc power transmission and distribution system, a fault pole and a fault occurrence section of the ground fault need to be rapidly determined so as to rapidly troubleshoot and eliminate the fault.
The structure and connection mode of a measuring system formed by the system are schematically shown in fig. 2, and each set of measuring system comprises a magnetic ring, a magnetic measuring element, a signal conditioning circuit, a microprocessor and a communication or display circuit. The magnetic measurement element is used for indirectly obtaining magnetic flux representing a direct current line current difference value in the magnetic ring, the conditioning circuit conditions signals output by the magnetic measurement element to a recognizable range of the signal acquisition and processing circuit, the signal processing circuit obtains a line ground fault pole and a fault current value through analysis, and the communication circuit is used for data transmission and networking. The magnetic ring in the measuring system is arranged on the positive and negative circuits at the direct current side, and the positive and negative power transmission linesThe power transmission line penetrates through the magnetic ring once and the two power transmission lines are positioned on the same diameter of the magnetic ring; the magnetic flux in the magnetic ring can be measured in any manner, and here, a magnetic measuring element is taken as an example, wherein the magnetic measuring element can be any component used for magnetic measurement, and can be a hall element, a giant magnetoresistance element and the like. And the most suitable magnetism is selected in a suitable range to meet the requirement that a magnetic measuring element is arranged on a reserved air gap of a magnetic ring, and the length l of the air gapgUnder the condition of satisfying the installation condition of the magnetic measuring element, the magnetic induction intensity in the air gap is ensured to be vertical to the magnetic measuring element as small as possible, so that the sectional area S of the magnetic ring satisfies lg/S<α, the parameter α in this formula is generally chosen between 2% and 5%. Meanwhile, the selected magnetic ring satisfies l/(mu)0μr)<<lg/μ0Time, air gap length lgShould press lg＝IFm×μ0/BmIs determined by determining in this formula IFmRepresents the maximum allowable ground fault current, l represents the average magnetic path length of the magnetic loop, mu0Denotes air permeability, μrRepresenting the relative permeability of the material of the magnetic ring, BmAnd the maximum magnetic flux density change value of the magnetic ring material is shown.
The signal conditioning circuit in the measuring system processes the signal from the magnetic measuring element, the actual effective resolution of the signal acquisition circuit is not lower than 12 bits, the corresponding microprocessor has certain processing and response speed, meets the requirement of the response time of the measuring device and is matched with the speed of the signal acquisition circuit, and the signal conditioning circuit can be a single chip microcomputer, a DSP, an embedded system or a common industrial personal computer and the like.
In the measuring system, a reaction earth fault current and a magnetic flux phi of an earth electrode are induced in the magnetic ring. When the true bipolar direct-current power transmission and distribution system normally works, the bipolar of the true bipolar direct-current power transmission and distribution system runs in a balanced mode, namely the currents flowing through the positive and negative power transmission lines are consistent in magnitude and opposite in direction, no ground fault current exists, and the magnetic flux phi on the magnetic ring is 0 at the moment; when a single-pole earth fault occurs on the direct current side, the current flowing in the positive and negative lines on the direct current side is not consistent any more, namely, the earth fault current I exists at the fault pointFSuppose that the ground fault has phi at the time of occurrence of the positive pole>0, then is groundedPhi when the failure occurs at the negative electrode<0. And the induced magnetic flux phi in the magnetic ring is proportional to the earth fault current IFI.e. with phi ═ kxIFThe fault current I can be calculated from the measured magnetic fluxFThe size of (2). The coefficient k passes the test standard current IF0Reading out the induced magnetic flux phi0(or other values related to the reactive flux) and calculating k ═ φ0/IF0And (4) obtaining.
A set of measuring system provided by the invention is arranged on a direct current side pipeline of a true bipolar direct current transmission and distribution system at certain intervals, and magnetic flux phi measured by a plurality of measuring points is obtained as shown in figure 31、φ2、…、φn. Once the positive pole or the negative pole of the direct current side has the ground fault, the fault pole and the fault section of the true bipolar unipolar ground fault can be judged according to the result of the response fault ground current measured by the measuring device. If the magnetic flux (phi) measured at two measuring points (a-th and b-th) which are closest to each otheraAnd phib) When one absolute value is maximum and the other absolute value is minimum (ideally 0), the monopolar earth fault occurring section is between the two measuring points; if the two measurement points are numbered with b>and a +1, indicating that a measurement system fails between two measurement points, and when the single-pole ground fault in the section is checked, the failure measurement system needs to be checked. Meanwhile, according to the characteristic that the true bipolar line has current transient when the unipolar ground fault occurs, the distance L of three measurement points (assuming that the measurement points are c, a and b in sequence) is determined by the a-th measurement point, the b-th measurement point and the adjacent measurement point of one of the two measurement pointsab、LcaAnd measuring the time difference of the transient to judge the position of the fault point. Assuming that a certain moment before the fault is a zero moment, the time for measuring the transient by the three measuring points is ta、tbAnd tcFrom this, it can be obtained that the distance of the fault point from the a-th and b-th measuring points is s1And s2Then there is
s1＝λ×(ta-t0) (4)
s2＝λ×(tb-t0) (5)
s1+Lca＝λ×(tc-t0) (6)
Lab＝s1+s2 (7)
From the equations (4) to (7), the distances between the failure point and the a-th and b-th measuring points are respectively
s1＝(Lab+β×Lca)/2 (8)
s2＝(Lab-β×Lca)/2 (9)
Wherein β ═ ta-tb)/(tc-ta). If the sequence of the measuring points is a, b and c, the analogy can be made.
Example (b):
the embodiment is to briefly explain an implementation process by combining the structure of the measurement system for detecting the single-pole ground fault of the true bipolar dc power transmission and distribution line in fig. 2 and the schematic diagram of the connection mode thereof, and the schematic diagram of the positioning principle of the single-pole ground fault of the true bipolar dc-side line in fig. 3.
The induced magnetic flux phi in the magnetic ring of the measurement system shown in FIG. 2 proposed in the present invention is proportional to the ground fault current IFI.e. with phi ═ kxIF(ii) a The coefficient k passes the test standard current IF0Reading out the induced magnetic flux phi0(or other values related to the reactive flux) and calculating k ═ φ0/IFAnd (4) obtaining. Assuming a known coefficient k0
(1) If the obtained magnetic flux phi is 0, the direct-current side of the true bipolar direct-current power transmission and distribution system normally works, namely the current flowing through the positive and negative power transmission lines is consistent in magnitude and opposite in direction, and no ground fault current exists;
(2) if the obtained magnetic flux phi is not equal to 0, the situation that the monopolar earth fault occurs on the direct current side of the true bipolar direct current power transmission and distribution system is shown, namely, the current flowing in the positive and negative lines on the direct current side is not consistent any more at the moment, and the earth fault current I exists at the fault pointF＝φ/k。
If phi is greater than 0, the earth fault occurs at the positive pole of the direct current transmission line;
if phi is less than 0, the grounding fault occurs at the negative pole of the direct current transmission line.
Referring to fig. 3, n sets of measuring systems provided by the present invention are installed on a dc power transmission and distribution system, and the numbers are from 1 to n. Measuring the magnetic flux phi of the magnetic ring in each measuring system1＝φ2>0 and the absolute value is maximum, phi4＝…＝φnWhen the direct current side line positive pole of the direct current transmission and distribution system has a unipolar ground fault, the fault section is between the measuring points 2 and 4. In addition, since the measurement points 2 and 4 are not adjacent, it is indicated that the measurement system of the measurement point 3 may fail, and therefore, when the positive ground fault point is inspected, the measurement system with the number 3 needs to be inspected.
And the distances between the measuring points 2 and 4 and the measuring point 1 adjacent to the measuring point 2 are respectively known as L1210km and L2420km, from the measured time difference of the transient β (t)a-tb)/(tc-ta) As a result, equations (8) and (9) can obtain distances from the fault points to the measurement points 2 and 4 of 7km and 13km, respectively.
Obviously, as described in the above embodiments, the present invention determines the magnitude of the ground fault current and the ground electrode according to the magnetic flux phi induced by the magnetic ring in the measurement system, and determines the position of the ground fault through a plurality of measurement systems installed on the dc line, so as to quickly and effectively find and eliminate the ground fault. The invention provides a single-pole ground fault detection system suitable for engineering practice and used for a true bipolar direct current transmission and distribution line.
The foregoing is a further detailed description of the invention in connection with specific embodiments thereof. It should be noted that the embodiments of the present invention are not limited to the above embodiments, and that those skilled in the art can make several deductions and extensions without departing from the spirit of the present invention, but should be construed as the scope of the patent protection defined by the appended claims.
Claims (2)
1. A single-pole ground fault detection system for a true bipolar direct current transmission and distribution line is characterized by comprising a plurality of measurement systems for monitoring the current of a direct current transmission line, wherein each measurement system comprises a magnetic ring for measuring the direct current, a related magnetic measurement element, a conditioning circuit, a signal acquisition and processing circuit and a communication circuit; wherein the content of the first and second substances,
the magnetic measurement element is used for indirectly obtaining magnetic flux representing a direct current line current difference value in the magnetic ring, the conditioning circuit conditions a signal output by the magnetic measurement element to a recognizable range of the signal acquisition and processing circuit, the signal processing circuit obtains a line ground fault pole and a fault current value through analysis, and the communication circuit is used for data transmission and networking; when the device is used, a set of measuring system is installed on a direct current side circuit of the true bipolar direct current transmission and distribution system at intervals of a set distance, and when the positive pole or the negative pole of the direct current side has an earth fault, the magnitude of the fault current, the fault pole and the fault position of the true bipolar unipolar earth fault are judged according to the result measured by the measuring device;
a magnetic ring in the measuring system is arranged on a positive circuit and a negative circuit on the direct current side, positive and negative power transmission lines penetrate through the magnetic ring once, and the two power transmission lines are positioned on the same diameter of the magnetic ring; the magnetic flux in the magnetic ring can be measured in any mode, the magnetic measuring element is arranged on a reserved air gap of the magnetic ring, and the length l of the air gapgUnder the condition of satisfying the installation condition of the magnetic measuring element, the magnetic induction intensity in the air gap is ensured to be vertical to the magnetic measuring element as small as possible, so that the sectional area S of the magnetic ring satisfies the requirement
lg/S<α (1)
Alpha in the formula is selected to be between 2 percent and 5 percent, and simultaneously, the selected magnetic ring satisfies l/(mu)0μr)<<lg/μ0Time, air gap length lgDetermined according to equation (2)
lg＝IFm×μ0/Bm (2)
In the formula IFmRepresents the maximum allowable ground fault current, l represents the average magnetic path length of the magnetic loop, mu0Denotes air permeability, μrRepresenting the relative permeability of the material of the magnetic ring, BmRepresenting the maximum magnetic flux density change value of the magnetic ring material, and comprehensively selecting a proper magnetic ring according to the requirement;
the conditioning circuit in the measuring system processes the signal from the magnetic measuring element, the actual effective resolution of the signal acquisition and processing circuit is not lower than 12 bits, and the corresponding microprocessor has preset processing and response speed, meets the requirement of the response time of the measuring device and is matched with the speed of the signal acquisition and processing circuit;
magnetic flux phi related to the earth fault current is induced in a magnetic ring in the measuring system, when a true bipolar direct current power transmission and distribution system works normally, the bipoles of the measuring system run in a balanced mode, namely the currents flowing through the positive and negative power transmission lines are consistent in magnitude and opposite in direction, the earth fault current does not exist, and the magnetic flux phi on the magnetic ring is 0 at the moment; when a single-pole earth fault occurs on the direct current side, the current flowing in the positive and negative lines on the direct current side is not consistent any more, namely, the earth fault current I exists at the fault pointFIf the earth fault occurs at the positive pole, phi>0, then the earth fault occurs at the negative pole with phi<0；
The induced magnetic flux phi in the magnetic ring of the measuring system is proportional to the earth fault current IFI.e. with phi ═ kxIFCalculating the fault current I from the measured magnetic fluxFThe size of (d); the coefficient k passes the test standard current IF0The corresponding induced magnetic flux phi0Is obtained by
k＝φ0/IF0 (3)
When a plurality of measuring systems are arranged on the direct current side circuit of the true bipolar direct current power transmission and distribution system, the magnetic flux phi measured by a plurality of measuring points is obtained1、φ2、…、φnIf the magnetic flux measured at the a-th and b-th measuring points closest to each other is phiaAnd phibIf one absolute value is maximum and the other absolute value is minimum, the monopolar earth fault occurring section is between the two measuring points; if the two measurement points are numbered with b>a +1, the possible failure of the measurement system between the two measurement points is simultaneously shown, and when the single-pole ground fault in the section is checked, the possible failure measurement system needs to be checked.
2. The monopolar ground fault detection system for the true bipolar dc power transmission and distribution line according to claim 1, wherein the monopolar ground fault point location of the true bipolar dc power transmission and distribution system is obtained as follows:
according to the characteristic that the unipolar earth fault of the true bipolar line has current transient at the moment, the distance L of three measurement points including the a th measurement point, the b th measurement point and the adjacent measurement point c of one of the two measurement pointsab、LcaMeasuring the transient time difference to judge the position of the fault point, wherein the sequence of the measurement points is assumed to be c, a and b; assuming that a certain moment before the fault is a zero moment, the time for measuring the transient by the three measuring points is ta、tbAnd tcThe distance of the faulty point from the a-th and b-th measuring points is respectively
s1＝(Lab+β×Lca)/2 (8)
s2＝(Lab-β×Lca)/2 (9)
Wherein β ═ ta-tb)/(tc-ta) If the sequence of the measuring points is a, b and c, and so on.
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| CN103475258B (en) * | 2013-09-09 | 2016-08-17 | 河海大学常州校区 | The high-voltage pulse power source of adjustable discharge parameter |
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| US10878997B2 (en) * | 2015-03-13 | 2020-12-29 | Taiwan Semiconductor Manufacturing Company, Ltd. | Integrated circuit having current-sensing coil |
| KR102539688B1 (en) * | 2016-04-28 | 2023-06-07 | 엘에스일렉트릭(주) | Leakage Current Detector |
| CN106370946B (en) * | 2016-08-24 | 2018-10-26 | 南方电网科学研究院有限责任公司 | Method for testing frequency limit control function of direct current transmission system |
| CN107359588B (en) * | 2016-09-22 | 2019-05-31 | 天津大学 | The very bipolar adaptive reclosing method of MMC-HVDC transmission system monopolar grounding fault |
| CN106877298B (en) * | 2017-03-27 | 2018-09-21 | 上海交通大学 | MMC-HVDC system dc line protection methods |
| CN108957227B (en) * | 2018-06-28 | 2020-09-29 | 杭州电子科技大学 | Cable fault position detection method |
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