CN110361628B - MMC direct current transmission line fault identification method based on SOD transformation - Google Patents

MMC direct current transmission line fault identification method based on SOD transformation Download PDF

Info

Publication number
CN110361628B
CN110361628B CN201910549576.6A CN201910549576A CN110361628B CN 110361628 B CN110361628 B CN 110361628B CN 201910549576 A CN201910549576 A CN 201910549576A CN 110361628 B CN110361628 B CN 110361628B
Authority
CN
China
Prior art keywords
fault
spmin
voltage
current data
transformation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201910549576.6A
Other languages
Chinese (zh)
Other versions
CN110361628A (en
Inventor
束洪春
代月
安娜
张雪飞
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kunming University of Science and Technology
Original Assignee
Kunming University of Science and Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kunming University of Science and Technology filed Critical Kunming University of Science and Technology
Priority to CN201910549576.6A priority Critical patent/CN110361628B/en
Publication of CN110361628A publication Critical patent/CN110361628A/en
Application granted granted Critical
Publication of CN110361628B publication Critical patent/CN110361628B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08—Locating faults in cables, transmission lines, or networks
    • G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
    • G01R31/085—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution lines, e.g. overhead

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)

Abstract

The invention relates to an MMC direct current transmission line fault identification method based on SOD transformation, and belongs to the technical field of power system relay protection. Firstly, reading fault voltage and fault current data acquired by a high-speed acquisition device at a measuring end; secondly, carrying out cross sequence differential SOD transformation on the obtained voltage and current data to obtain Su (n) and Si (n); finally, multiplying Su (n) and Si (n) to obtain Sp (n), and taking the minimum value Spmin of Sp (n) to judge the fault; when Spmin is > -20, judging that the fault is an out-of-range fault; when the Spmin is more than-450 and less than-20, the fault is judged to be the positive earth fault; and when Spmin is less than-450, judging the fault as the bipolar short circuit fault. The invention adopts single-end voltage and current data, then carries out differential calculation and SOD transformation on the voltage and current data in sequence, further identifies the single-pole grounding fault, the double-pole short-circuit fault and the outside fault, and can reliably and sensitively identify the fault without communicating with the opposite end signal.

Description

MMC direct current transmission line fault identification method based on SOD transformation
Technical Field
The invention relates to an MMC direct current transmission line fault identification method based on SOD transformation, and belongs to the technical field of power system relay protection.
Background
MMC-HVDC is a novel direct current transmission technology, has shallow engineering experience at home and abroad, and has short research time. Scholars at home and abroad carry out relevant research on the topological structure and the operation principle of the MMC-HVDC system to obtain abundant results, but the relevant research mainly focuses on the aspects of the basic principle and the control strategy of the MMC-HVDC system, and few researches on the fault characteristic analysis of the MMC-HVDC system and the proposed line protection method are carried out. In only a few fault characteristic analyses, the analysis content mainly aims at the system direct current side line fault.
Once a fault occurs in a high-voltage operating environment, a power transmission system is likely to be subjected to overvoltage and overcurrent power transmission impact, and the whole power transmission system is damaged. MMC-HVDC is an important power transmission device, and needs to operate reliably for a long time, when a fault occurs, the system is ensured not to be damaged, and fault recovery support is rapidly provided for the fault system, so that a protection strategy for the MMC-HVDC system is very important.
The MMC-HVDC system is applied to electric power of an electric power system by the superiority, because the structure and the operation mode of the MMC-HVDC system are different from those of a traditional thyristor converter, the MMC-HVDC system does not have direct current filters at two ends of a line, and the applicability problem of a protection and positioning method of a traditional direct current transmission line with the direct current filters as boundaries in the system is worthy of research.
Disclosure of Invention
The invention aims to solve the technical problem of providing an MMC direct current transmission line fault identification method based on SOD transformation, which traverses different faults in the whole line length range and the alternating current side, and distinguishes fault types by utilizing the cross sequence differential transformation of voltage and current variation trends so as to solve the problems.
The technical scheme of the invention is as follows: a fault identification method of an MMC direct current transmission line based on SOD transformation comprises the steps of firstly reading fault voltage and fault current data obtained by a high-speed acquisition device at a measuring end; secondly, carrying out cross sequence differential SOD transformation on the obtained voltage and current data to obtain Su (n) and Si (n); finally, multiplying Su (n) and Si (n) to obtain Sp (n), and taking the minimum value Spmin of Sp (n) to judge the fault; when Spmin is > -20, judging that the fault is an out-of-range fault; when the Spmin is more than-450 and less than-20, the fault is judged to be the positive earth fault; and when Spmin is less than-450, judging the fault as the bipolar short circuit fault.
The method comprises the following specific steps:
step 1: when a power transmission system fails, an initial fault voltage u is obtained at a measurement pointMAnd fault current iM；
Step 2: intercepting fault voltage and current data in a 2ms time window, and respectively carrying out 4-order cross sequence differential transformation on the acquired voltage and current data to obtain Su (n) and Si (n);
Su(n)＝uM(n)-4×uM(n-1)+6×uM(n-2)-4×uM(n-3)+uM(n-4) (1)
Si(n)＝iM(n)-4×iM(n-1)+6×iM(n-2)-4×iM(n-3)+iM(n-4) (2)
in the formula uMRepresenting the voltage at the measuring terminal, iMThe current of a measuring end is shown, and n represents the number of sampling points;
step 3: carrying out differential transformation on the crossed sequence in Step2 to obtain Su (n) and Si (n) to multiply to obtain Sp (n), and taking the minimum value of Sp (n);
Sp(n)＝Su(n)×Si(n) (3)
step 4: forming a fault identification criterion by using the minimum value Spmin of Sp (n):
when Spmin is > -20, judging that the fault is an out-of-range fault;
when the Spmin is more than-450 and less than-20, the fault is judged to be the positive earth fault;
and when Spmin is less than-450, judging the fault as the bipolar short circuit fault.
The sampling rate in the invention is 10 kHz.
The principle of the invention is as follows: the method comprises the steps that a high-speed acquisition device at a measuring end acquires fault voltage and fault current, then differential calculation is carried out on the voltage and the current respectively to obtain voltage and current change trends, as the fault types cannot be distinguished obviously according to the voltage and current change trends, the fault characteristics are amplified through SOD (super oxide dismutase) conversion, the voltage and current change trends are respectively subjected to cross sequence differential conversion, and finally, a product of the voltage and the current change trends forms a protection discriminant, so that different fault types are identified.
The invention has the beneficial effects that:
1. the MMC direct-current transmission line protection adopts single-ended voltage and current data, then differential calculation and SOD conversion are sequentially carried out on the voltage and current data, and then unipolar ground faults, bipolar short-circuit faults and external faults are identified, and the faults can be reliably and sensitively identified without signal communication with an opposite terminal.
2. The voltage and current change trend after 4-order cross sequence differential transformation theoretically strengthens the change degree, filters low-frequency signals, is beneficial to eliminating noise, and can better distinguish the fault curves inside and outside the region.
3. The time window taken by the invention is 2ms, the quick action is better, and the method has better application prospect.
Drawings
FIG. 1 is a block diagram of an MMC DC power transmission system in an embodiment of the present invention;
fig. 2 is a waveform diagram formed by taking the minimum value Spmin of sp (n) under each fault distance condition when the full-length line traverses the positive ground fault in embodiment 1 of the present invention;
fig. 3 is a waveform diagram formed by taking the minimum value Spmin of sp (n) under each fault distance condition when traversing the bipolar short-circuit fault in the full length of the line in embodiment 2 of the present invention;
fig. 4 is a bar graph of the minimum value Spmin of sp (n) for each fault type when there is a fault on the ac side of the rectifier station in embodiment 3 of the present invention;
fig. 5 is a bar chart of the minimum value Spmin of sp (n) for each fault type in the case of the ac side fault of the inverter station in embodiment 4 of the present invention.
Detailed Description
The invention is further described with reference to the following drawings and detailed description.
Example 1: an MMC high-voltage direct-current transmission system as shown in the attached figure 1 is established as a simulation model. The valve side windings of the connecting transformer are connected in a triangular mode and have no neutral point, the alternating current sides of the connecting transformer are connected in a star mode, and the neutral point is directly grounded. The direct current side is grounded through a clamping resistor, the resistance value of the clamping resistor is large, and the main function is to clamp the voltage of two poles and provide a potential reference point for a direct current system during normal operation. The direct current voltage is +/-320 kV, the power transmission line is 400km, and M is a measuring end.
(1) Fault location: positive earth fault f1160km away from the measuring end; the starting time of the fault is 0.4 s; the sampling frequency was 10 kHz.
(2) Fault voltage and current data are acquired at the measurement point according to the first step in the specification.
(3) According to the second step in the specification, fault voltage and current data in a 2ms time window are taken, and the voltage and the current are respectively subjected to SOD conversion to obtain Su (n) and Si (n).
(4) According to the third step of the specification, multiplying Su (n) and Si (n) obtained by cross sequence differential transformation to obtain Sp (n), and taking the minimum value of Sp (n).
(5) According to the protection criterion, when Spmin is > -20, judging that the fault is an out-of-area fault; when the Spmin is more than-450 and less than-20, the fault is judged to be the positive earth fault; when Spmin is less than-450, it is determined as a double short-circuit fault, and in this example, because Spmin is equal to-152.5371, it is determined as a positive ground fault.
Example 2: an MMC high-voltage direct-current transmission system as shown in the attached figure 1 is established as a simulation model. The valve side windings of the connecting transformer are connected in a triangular mode and have no neutral point, the alternating current sides of the connecting transformer are connected in a star mode, and the neutral point is directly grounded. The direct current side is grounded through a clamping resistor, the resistance value of the clamping resistor is large, and the main function is to clamp the voltage of two poles and provide a potential reference point for a direct current system during normal operation. The direct current voltage is +/-320 kV, the power transmission line is 400km, and M is a measuring end.
(1) Fault location: bipolar short-circuit fault f2160km away from the measuring end; the starting time of the fault is 0.4 s; the sampling frequency was 10 kHz.
(2) Fault voltage and current data are acquired at the measurement point according to the first step in the specification.
(3) According to the second step in the specification, fault voltage and current data in a 2ms time window are taken, and the voltage and the current are respectively subjected to SOD conversion to obtain Su (n) and Si (n).
(4) According to the third step of the specification, multiplying Su (n) and Si (n) obtained by cross sequence differential transformation to obtain Sp (n), and taking the minimum value of Sp (n).
(5) According to the protection criterion, when Spmin is > -20, judging that the fault is an out-of-area fault; when the Spmin is more than-450 and less than-20, the fault is judged to be the positive earth fault; when Spmin is less than-450, it is determined as a double short-circuit fault, and in this example, Spmin is equal to-882.3616, and thus it is determined as a double short-circuit fault.
Example 3: an MMC high-voltage direct-current transmission system as shown in the attached figure 1 is established as a simulation model. The valve side windings of the connecting transformer are connected in a triangular mode and have no neutral point, the alternating current sides of the connecting transformer are connected in a star mode, and the neutral point is directly grounded. The direct current side is grounded through a clamping resistor, the resistance value of the clamping resistor is large, and the main function is to clamp the voltage of two poles and provide a potential reference point for a direct current system during normal operation. The direct current voltage is +/-320 kV, the power transmission line is 400km, and M is a measuring end.
(1) Fault location: three-phase short-circuit fault f on alternating current side of rectifier station3(ii) a The starting time of the fault is 0.4 s; the sampling frequency was 10 kHz.
(2) Fault voltage and current data are acquired at the measurement point according to the first step in the specification.
(3) According to the second step in the specification, fault voltage and current data in a 2ms time window are taken, and the voltage and the current are respectively subjected to SOD conversion to obtain Su (n) and Si (n).
(4) According to the third step of the specification, multiplying Su (n) and Si (n) obtained by cross sequence differential transformation to obtain Sp (n), and taking the minimum value of Sp (n).
(5) According to the protection criterion, when Spmin is > -20, judging that the fault is an out-of-area fault; when the Spmin is more than-450 and less than-20, the fault is judged to be the positive earth fault; when Spmin is less than-450, it is determined as a double short-circuit fault, and in this example, Spmin is-0.0955, and thus it is determined as an out-of-range fault.
Example 4: an MMC high-voltage direct-current transmission system as shown in the attached figure 1 is established as a simulation model. The valve side windings of the connecting transformer are connected in a triangular mode and have no neutral point, the alternating current sides of the connecting transformer are connected in a star mode, and the neutral point is directly grounded. The direct current side is grounded through a clamping resistor, the resistance value of the clamping resistor is large, and the main function is to clamp the voltage of two poles and provide a potential reference point for a direct current system during normal operation. The direct current voltage is +/-320 kV, the power transmission line is 400km, and M is a measuring end.
(1) Fault location: three-phase short-circuit fault f on alternating current side of inverter station4(ii) a The starting time of the fault is 0.4 s; the sampling frequency was 10 kHz.
(2) Fault voltage and current data are acquired at the measurement point according to the first step in the specification.
(3) According to the second step in the specification, fault voltage and current data in a 2ms time window are taken, and the voltage and the current are respectively subjected to SOD conversion to obtain Su (n) and Si (n).
(4) According to the third step of the specification, multiplying Su (n) and Si (n) obtained by cross sequence differential transformation to obtain Sp (n), and taking the minimum value of Sp (n).
(5) According to the protection criterion, when Spmin is > -20, judging that the fault is an out-of-area fault; when the Spmin is more than-450 and less than-20, the fault is judged to be the positive earth fault; when Spmin is less than-450, it is determined as a double short-circuit fault, and in this example, since Spmin is-0.0193, it is determined as an out-of-range fault.
While the present invention has been described in detail with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, and various changes can be made without departing from the spirit and scope of the present invention.

Claims (2)

1. A fault identification method for an MMC direct current transmission line based on SOD transformation is characterized in that: firstly, reading fault voltage and fault current data acquired by a high-speed acquisition device at a measuring end; secondly, carrying out cross sequence differential SOD transformation on the obtained voltage and current data to obtain Su (n) and Si (n); finally, multiplying Su (n) and Si (n) to obtain Sp (n), and taking the minimum value Spmin of Sp (n) to judge the fault; when Spmin is > -20, judging that the fault is an out-of-range fault; when the Spmin is more than-450 and less than-20, the fault is judged to be the positive earth fault; and when Spmin is less than-450, judging the fault as the bipolar short circuit fault.
2. The MMC direct current transmission line fault identification method based on SOD transformation of claim 1, characterized in that the concrete steps are:
step 1: when a power transmission system fails, an initial fault voltage u is obtained at a measurement pointMAnd fault current iM；
Step 2: intercepting fault voltage and current data in a 2ms time window, and respectively carrying out 4-order cross sequence differential transformation on the acquired voltage and current data to obtain Su (n) and Si (n);
Su(n)＝uM(n)-4×uM(n-1)+6×uM(n-2)-4×uM(n-3)+uM(n-4) (1)
Si(n)＝iM(n)-4×iM(n-1)+6×iM(n-2)-4×iM(n-3)+iM(n-4) (2)
in the formula uMRepresenting the voltage at the measuring terminal, iMThe current of a measuring end is shown, and n represents the number of sampling points;
step 3: carrying out differential transformation on the crossed sequence in Step2 to obtain Su (n) and Si (n) to multiply to obtain Sp (n), and taking the minimum value of Sp (n);
Sp(n)＝Su(n)×Si(n) (3)
step 4: forming a fault identification criterion by using the minimum value Spmin of Sp (n):
when Spmin is > -20, judging that the fault is an out-of-range fault;
when the Spmin is more than-450 and less than-20, the fault is judged to be the positive earth fault;
and when Spmin is less than-450, judging the fault as the bipolar short circuit fault.
CN201910549576.6A 2019-06-24 2019-06-24 MMC direct current transmission line fault identification method based on SOD transformation Active CN110361628B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201910549576.6A CN110361628B (en) 2019-06-24 2019-06-24 MMC direct current transmission line fault identification method based on SOD transformation

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201910549576.6A CN110361628B (en) 2019-06-24 2019-06-24 MMC direct current transmission line fault identification method based on SOD transformation

Publications (2)

Publication Number Publication Date
CN110361628A CN110361628A (en) 2019-10-22
CN110361628B true CN110361628B (en) 2021-07-06

Family

ID=68216841

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201910549576.6A Active CN110361628B (en) 2019-06-24 2019-06-24 MMC direct current transmission line fault identification method based on SOD transformation

Country Status (1)

Country Link
CN (1) CN110361628B (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110824299B (en) * 2019-11-25 2021-11-16 云南电网有限责任公司临沧供电局 Fault line selection method based on two-dimensional plane judgment of zero-sequence current curve cluster
CN110927525A (en) * 2019-12-03 2020-03-27 昆明理工大学 Line fault identification PCA clustering method based on voltage change SOD curve cluster

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013004285A1 (en) * 2011-07-04 2013-01-10 Abb Research Ltd System for detecting internal winding faults of a synchronous generator, computer program product and method

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0646860A (en) * 1992-09-25 1994-02-22 Nippon Kayaku Co Ltd New dna capable of coding human sod and microorganism having the same
CN101931212B (en) * 2010-08-27 2012-12-12 西安交通大学 Transformer self-adaptive protector and protection method thereof
CN102156246A (en) * 2011-03-24 2011-08-17 昆明理工大学 Wavelet energy entropy detecting method for recognizing faults of ultra-high voltage direct-current transmission line
CN104655981A (en) * 2014-11-05 2015-05-27 昆明理工大学 Comparison type directional protection method for travelling wave polarity by utilizing crossing sequence differential transformation
CN107390046B (en) * 2017-06-19 2019-08-30 天津大学 A kind of high voltage direct current transmission line fault type judgement method

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013004285A1 (en) * 2011-07-04 2013-01-10 Abb Research Ltd System for detecting internal winding faults of a synchronous generator, computer program product and method

Also Published As

Publication number Publication date
CN110361628A (en) 2019-10-22

Similar Documents

Publication Publication Date Title
CN103018627B (en) Adaptive fault type fault line detection method for non-effectively earthed system
CN111983376B (en) Intra-regional and extra-regional fault protection method based on cosine similarity
CN113381391B (en) Single-end protection method for high-voltage direct-current transmission line
CN110361628B (en) MMC direct current transmission line fault identification method based on SOD transformation
CN106980069B (en) High-resistance grounding fault positioning method based on transient current projection coefficient difference comparison
CN111463764B (en) Direct-current transmission line protection method based on initial voltage traveling wave frequency domain attenuation rate
CN110350493B (en) Medium-voltage flexible direct-current system fault detection method based on line current second-order derivative
CN104237703A (en) Method for recognizing properties of three-phase adaptive re-closing faults of lines with parallel reactors
CN112285601A (en) Multi-terminal low-current grounding flexible direct current system single-pole grounding fault line selection method
CN110542823A (en) Distribution line single-phase earth fault section positioning method
CN112014773A (en) Method for detecting early fault of small current grounding system cable
CN105186491A (en) Assessment method for overvoltage on primary side of electric power system caused by switching operation
CN110907753B (en) HHT energy entropy based MMC-HVDC system single-ended fault identification method
CN110137920B (en) MMC direct-current transmission line protection method based on voltage correlation
CN103743993B (en) A kind of method detecting deformation of transformer winding
Lei et al. A faulty pole detection method for the VSC-HVDC system based on the aperiodic component energy
CN110187220B (en) MMC direct current transmission line fault identification method based on correlation
CN110601153B (en) Relay protection method for single-end quantity of direct-current power distribution network
Yu et al. A sensitive single-end DC line fault detection method for MMC-HVDC grids using reactor voltage ratio
CN112039034B (en) MMC direct current transmission line pilot protection method based on modulus correlation
US20210351582A1 (en) Grounding Fault Protection Method for High-voltage Capacitor of Direct-current Filter
CN111030063B (en) Segmented time domain capacitance current compensation method
CN210327034U (en) High-voltage passive filter protection system
CN112505490A (en) Power distribution network single-phase earth fault line selection method based on mutual difference absolute value sum
CN114142442A (en) Direct-current transmission line protection method and system

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant