CN109142967B - Variable time limit distance protection distance measurement method and device for power grid line - Google Patents

Variable time limit distance protection distance measurement method and device for power grid line Download PDF

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CN109142967B
CN109142967B CN201810784885.7A CN201810784885A CN109142967B CN 109142967 B CN109142967 B CN 109142967B CN 201810784885 A CN201810784885 A CN 201810784885A CN 109142967 B CN109142967 B CN 109142967B
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CN109142967A (en
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周泽昕
李天华
曹虹
郭雅蓉
杜丁香
王兴国
程琪
王德林
吕鹏飞
刘宇
张志�
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State Grid Corp of China SGCC
China Electric Power Research Institute Co Ltd CEPRI
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State Grid Corp of China SGCC
China Electric Power Research Institute Co Ltd CEPRI
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    • 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
    • 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
    • G01R31/088—Aspects of digital computing
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S10/00—Systems supporting electrical power generation, transmission or distribution
    • Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
    • Y04S10/52—Outage or fault management, e.g. fault detection or location

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Abstract

The invention provides a variable time-limit distance protection distance measurement method and a variable time-limit distance protection distance measurement device for a power grid line. The time-limited distance protection and ranging method and the time-limited distance protection and ranging device for the power grid line can accurately position a fault point when the fault of the power grid line occurs in the range of the distance protection section, and the error is 1 e-3.

Description

Variable time limit distance protection distance measurement method and device for power grid line
Technical Field
The invention relates to the field of relay protection, in particular to a time-limited distance protection distance measurement method and device for a power grid line.
Background
Setting calculation and correct fixed value are necessary conditions for ensuring that the relay protection device can play normal performance, and the relay protection setting of the current power grid comprises line protection, bus protection, transformer protection, breaker protection, failure protection overvoltage, long-jump protection and the like. The setting value of most of protection during the capital construction input can adapt to the local change of the power grid, and the setting value is not frequently changed generally. And the distance backup protection of the line protection needs to be matched with the distance backup protection of the adjacent line, and in the process of breaking and building the power grid line, the fixed value of the related line needs to be recalculated and issued to the related substation to change the fixed value. In fact, the inconsistency of the infrastructure project plan and implementation, the fixed value to be changed cannot be in place at one time, and the fixed value in the changing process is often out of fit.
The variable time limit distance protection utilizes relevant parameters of the distance protection during the line fault action, such as the distance between a fault point and a protection installation position, collected line voltage and current and the like, and relevant off-line information, such as impedance fixed values of all distance protection sections, line length and the like, to automatically calculate the action time limit, so that the automatic matching of the adjacent line distance protection action time limit can be realized. Therefore, in the variable time-limit distance protection, accurately measuring the distance between the fault point and the protection installation place becomes a key point influencing the calculation accuracy of the protection action time limit in the variable time-limit distance protection.
Disclosure of Invention
The invention provides a variable time-limit distance protection distance measuring method and device for a power grid line, aiming at solving the technical problem that the prior art lacks a method and device for accurately measuring the distance between a fault point of the power grid line and a protection installation position in variable time-limit distance protection. The invention discloses a time-limited distance protection and ranging method for a power grid line, which comprises the following steps:
determining whether the line fault is a single-phase fault or a phase-to-phase fault;
when the line fault is a single-phase fault, the phase voltage is changed according to the fault
Figure BDA0001733494670000021
Fault phase current
Figure BDA0001733494670000022
Setting an impedance value ZZDFNi(1)And zero sequence current i0Determining whether m-i distance protection segments starting from a distance protection i segment satisfy respective established criterion of grounded reactance line F1i(1)Zero-sequence reactance line criterion F2i(1)If and only if m-i distance protection sections starting from the distance protection section i all satisfy the respective established criterion of grounded reactance line F1i(1)Zero-sequence reactance line criterion F2i(1)Starting from j-2, the established grounding reactance line criterion F1 of the distance protection i section is usedi(j)Zero-sequence reactance line criterion F2i(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)Wherein i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10;
when the line fault is a phase-to-phase fault, the phase-to-phase voltage is determined according to the fault
Figure BDA0001733494670000023
Fault phase current
Figure BDA0001733494670000024
And setting an impedance value ZZDFNi(1)Determining whether m-i distance protection segments starting from a distance protection i segment satisfy respective established interphase reactance line criterion F3i(1)If and only if m-i distance protection sections starting from the distance protection section i all satisfy the respective established interphase reactance line criterion F3i(1)Starting from j to 2, the criterion F3 is determined according to the established interphase reactance line of the distance protection i sectioni(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)Wherein i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10;
according to a preset impedance value B of each kilometer of a protection installation position and a voltage transformer transformation ratio NptCurrent transformer transformation ratio NctAnd the setting impedance value Z of the distance protection i section when j is equal to n-1ZDFNi(n-1)The distance C between the line fault point and the protection installation is calculated.
Further, before determining that the line fault is a single-phase fault or a phase-to-phase fault, the method comprises the following steps:
collecting instantaneous values of secondary values of three-phase voltage and current at a variable time-limit distance protection installation position;
determining the three-phase voltage fundamental wave phasor value according to the acquired instantaneous values of the secondary values of the three-phase voltage and the current
Figure BDA0001733494670000025
Sum current fundamental phasor value
Figure BDA0001733494670000026
Protecting the current fundamental wave phasor value at the installation site according to the variable time-limit distance
Figure BDA0001733494670000027
Calculating zero sequence current
Figure BDA0001733494670000028
The respective fixed value Z of m-1 distance protection sections at the protection installation positionZDiRespectively as its setting impedance value ZZDFNi(j)A value when j is 1, wherein i is more than or equal to 1 and less than m, and m is a natural number more than 3;
setting a primary impedance value B and a transformation ratio N of the voltage transformer at a protection installation position per kilometerptAnd current transformer transformation ratio NctA value of (d);
establishing a grounding reactance line criterion, a zero sequence reactance line criterion and an interphase reactance line criterion of each distance protection section, wherein:
the formula of the criterion of the grounding reactance line is as follows:
Figure BDA0001733494670000031
the formula of the zero-sequence reactance line criterion is as follows:
Figure BDA0001733494670000032
the formula of the criterion of the interphase reactance line is as follows:
Figure BDA0001733494670000033
in the formula, K is a preset zero sequence compensation coefficient,
Figure BDA0001733494670000034
is a fault phase voltage, the value of which is the voltage fundamental wave phase value of the fault phase,
Figure BDA0001733494670000035
is the voltage between the faulty phases, whose value is the difference of the phase values of the voltage fundamental wave between the faulty phases,
Figure BDA0001733494670000036
is a fault phase current, the value of which is the current fundamental wave phasor value of the fault phase,
Figure BDA0001733494670000037
is the fault phase current, whose value is the difference of the current fundamental wave phasor value of the fault phase,
Figure BDA00017334946700000314
is zero sequence current, ZZDFNi(j)Is setting impedance of j times of i section of distance protection, wherein i is more than or equal to 1<m,2≤j<n, m is a natural number greater than 3, and n is a natural number greater than 10.
Further, when the line fault is a single-phase fault, the phase voltage is changed according to the fault
Figure BDA0001733494670000038
Fault phase current
Figure BDA0001733494670000039
Setting an impedance value ZZDFNi(1)And zero sequence current
Figure BDA00017334946700000312
Determining whether m-i distance protection segments starting from a distance protection i segment satisfy respective established criterion of grounded reactance line F1i(1)Zero-sequence reactance line criterion F2i(1)If and only if m-i distance protection sections starting from the distance protection section i all satisfy the respective established criterion of grounded reactance line F1i(1)Zero-sequence reactance line criterion F2i(1)Starting from j-2, the established grounding reactance line criterion F1 of the distance protection i section is usedi(j)Zero-sequence reactance line criterion F2i(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)The method comprises the following steps:
connecting the fault phase voltage
Figure BDA00017334946700000310
Fault phase current
Figure BDA00017334946700000311
And the determined setting impedance value ZZDFNi(1)And zero sequence current
Figure BDA00017334946700000313
Formula F1 substituted into criterion of grounding reactance linei(1)Formula F2 for criterion of zero-sequence reactance linei(1)When the distance protection sections m-i from the distance protection section i meet the requirement of less than or equal to 90 degrees F1i(1)F2 is less than or equal to 270 degrees and less than or equal to 90 degreesi(1)When the angle is less than or equal to 270 degrees, finishing the distance measurement;
when m-i distance protection sections starting from the distance protection section i all meet the condition that the angle is less than or equal to 90 degrees and less than or equal to F1i(1)F2 is less than or equal to 270 degrees and less than or equal to 90 degreesi(1)When the angle is less than or equal to 270 degrees, starting from j to 2, the criterion F1 is determined according to the established grounding reactance line of the distance protection section ii(j)Zero-sequence reactance line criterion F2i(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)The formula is as follows:
when the distance protection i section meets the condition that the angle is less than or equal to 90 degrees, F1i(j-1)F2 is less than or equal to 270 degrees and less than or equal to 90 degreesi(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)-0.5j-1*ZZDi
when the distance protection i section does not meet the condition that the angle is less than or equal to 90 degrees, F1i(j-1)F2 is less than or equal to 270 degrees or less than or equal to 90 degreesi(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)+0.5j-1*ZZDi
in the formula, i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10.
Further, when the line fault is a phase-to-phase fault, the phase-to-phase voltage is determined according to the fault
Figure BDA0001733494670000041
Fault phase current
Figure BDA0001733494670000042
And setting an impedance value ZZDFNi(1)Determining whether m-i distance protection segments starting from a distance protection i segment satisfy respective established interphase reactance line criterion F3i(1)If and only if m-i distance protection sections starting from the distance protection section i all satisfy the respective established interphase reactance line criterion F3i(1)Starting from j to 2, the criterion F3 is determined according to the established interphase reactance line of the distance protection i sectioni(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)The method comprises the following steps:
will fail the phase-to-phase voltage
Figure BDA0001733494670000043
Fault phase current
Figure BDA0001733494670000044
And setting an impedance value ZZDFNi(1)Respectively substituted into interphase reactance line criterion F3i(1)When the distance protection sections m-i from the distance protection section i meet the requirement of less than or equal to 90 degrees F3i(1)F3 is less than or equal to 270 degrees and less than or equal to 90 degreesi(1)When the angle is less than or equal to 270 degrees, finishing the distance measurement;
when m-i distance protection sections starting from the distance protection section i all meet the condition that the angle is less than or equal to 90 degrees and less than or equal to F3i(1)When the angle is less than or equal to 270 degrees, starting from j to 2, and according to the established interphase reactance line criterion F3 of the distance protection section ii(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)The formula is as follows:
when the distance protection i section meets the condition that the angle is less than or equal to 90 degrees, F3i(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)-0.5j-1*ZZDi
when the distance protection i section does not meet the condition that the angle is less than or equal to 90 degrees, F3i(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)+0.5j-1*ZZDi
in the formula, i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10.
Further, according to a preset impedance one-time value B and a voltage transformer transformation ratio N of each kilometer of a protection installation positionptCurrent transformer transformation ratio NctAnd the setting impedance value Z of the distance protection i section when j is equal to n-1ZDFNi(n-1)The formula for calculating the distance C between the line fault point and the protection installation is:
C＝(ZZDFNi(n-1)×(Npt/Nct))/B
wherein B is a set value of an impedance value per kilometer at a protection installation site, and N isptIs the transformation ratio of the voltage transformer, NctIs the current transformer transformation ratio, ZZDFNi(n-1)Is the setting impedance value Z of the distance protection i section when j is equal to n-1ZDFNi(n-1)。
According to another aspect of the present invention, there is provided a variable time-limited distance protection ranging apparatus for a power grid line, the apparatus comprising:
a fault type determination unit for determining whether the line fault is a single-phase fault or a phase-to-phase fault;
a third calculation unit for, when the line fault is a single-phase fault, calculating a phase voltage according to the fault
Figure BDA0001733494670000051
Fault phase current
Figure BDA0001733494670000052
Setting an impedance value ZZDFNi(1)And zero sequence current
Figure BDA0001733494670000055
Determining whether m-i distance protection segments starting from a distance protection i segment satisfy respective established criterion of grounded reactance line F1i(1)Zero-sequence reactance line criterion F2i(1)If and only if m-i distance protection sections starting from the distance protection section i all satisfy the respective established criterion of grounded reactance line F1i(1)Zero-sequence reactance line criterion F2i(1)When the current time is shorter, starting from j to 2,criterion F1 according to grounding reactance line established at distance protection i sectioni(j)Zero-sequence reactance line criterion F2i(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)Wherein i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10;
a fourth calculation unit for calculating a phase-to-phase voltage according to the fault when the line fault is a phase-to-phase fault
Figure BDA0001733494670000053
Fault phase current
Figure BDA0001733494670000054
And setting an impedance value ZZDFNi(1)Determining whether m-i distance protection segments starting from a distance protection i segment satisfy respective established interphase reactance line criterion F3i(1)If and only if m-i distance protection sections starting from the distance protection section i all satisfy the respective established interphase reactance line criterion F3i(1)Starting from j to 2, the criterion F3 is determined according to the established interphase reactance line of the distance protection i sectioni(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)Wherein i is more than or equal to 1 and less than m, and j is more than or equal to 2<n, m is a natural number greater than 3, n is a natural number greater than 10;
a fifth calculating unit for calculating the transformation ratio N of the voltage transformer according to the preset primary value B of the impedance per kilometer at the protection installation positionptCurrent transformer transformation ratio NctAnd the setting impedance value Z of the distance protection i section when j is equal to n-1ZDFNi(n-1)The distance C between the line fault point and the protection installation is calculated.
Further, the apparatus further comprises:
the data acquisition unit is used for acquiring instantaneous values of secondary values of three-phase voltage and current at a variable time-limit distance protection installation position;
a first computing unit for calculating the three points according to the acquisitionDetermining three-phase voltage fundamental wave phasor value by instantaneous value of phase voltage and current secondary value
Figure BDA0001733494670000061
Sum current fundamental phasor value
Figure BDA0001733494670000065
And protecting the secondary value of the current fundamental wave phasor at the installation according to the variable time limit distance
Figure BDA0001733494670000066
Calculating zero sequence current
Figure BDA0001733494670000067
A second calculation unit for calculating a fixed value Z for each of the m-1 distance protection segments at the protection installation siteZDiRespectively as its setting impedance value ZZDFNi(j)A value when j is 1, wherein 1. ltoreq. i<m, m is a natural number more than 3;
a parameter setting unit for setting a primary value B of impedance per kilometer at a protection installation site and a transformation ratio N of the voltage transformerptAnd current transformer transformation ratio NctAnd establishing a grounding reactance line criterion, a zero sequence reactance line criterion and an interphase reactance line criterion of each distance protection section, wherein:
the formula of the criterion of the grounding reactance line is as follows:
Figure BDA0001733494670000062
the formula of the zero-sequence reactance line criterion is as follows:
Figure BDA0001733494670000063
the formula of the criterion of the interphase reactance line is as follows:
Figure BDA0001733494670000064
in the formula, K is a preset zero sequence compensation coefficient,
Figure BDA0001733494670000071
is a fault phase voltage, the value of which is the voltage fundamental wave phase value of the fault phase,
Figure BDA0001733494670000072
is the voltage between the faulty phases, whose value is the difference of the phase values of the voltage fundamental wave between the faulty phases,
Figure BDA0001733494670000073
is a fault phase current, the value of which is the current fundamental wave phasor value of the fault phase,
Figure BDA0001733494670000074
is the fault phase current, whose value is the difference of the current fundamental wave phasor value of the fault phase,
Figure BDA0001733494670000079
is zero sequence current, ZZDFNi(j)The setting impedance of the jth time of the i section of the distance protection is represented, wherein i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number which is more than 3, and n is a natural number which is more than 10.
Further, the third calculation unit calculates a phase voltage according to the fault phase when the line fault is a single-phase fault
Figure BDA0001733494670000075
Fault phase current
Figure BDA0001733494670000076
Setting an impedance value ZZDFNi(1)And zero sequence current
Figure BDA00017334946700000710
Determining whether m-i distance protection segments starting from a distance protection i segment satisfy respective established criterion of grounded reactance line F1i(1)Zero-sequence reactance line criterion F2i(1)If and only if m-i distance protection segments starting from the distance protection i segment satisfy each already-satisfied distance protection segmentEstablished grounding reactance line criterion F1i(1)Zero-sequence reactance line criterion F2i(1)Starting from j-2, the established grounding reactance line criterion F1 of the distance protection i section is usedi(j)Zero-sequence reactance line criterion F2i(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)The method comprises the following steps:
connecting the fault phase voltage
Figure BDA0001733494670000077
Fault phase current
Figure BDA0001733494670000078
And the determined setting impedance value ZZDFNi(1)And zero sequence current
Figure BDA00017334946700000711
Formula F1 substituted into criterion of grounding reactance linei(1)Formula F2 for criterion of zero-sequence reactance linei(1)When the distance protection sections m-i from the distance protection section i meet the requirement of less than or equal to 90 degrees F1i(1)F2 is less than or equal to 270 degrees and less than or equal to 90 degreesi(1)When the angle is less than or equal to 270 degrees, finishing the distance measurement;
when m-i distance protection sections starting from the distance protection section i all meet the condition that the angle is less than or equal to 90 degrees and less than or equal to F1i(1)F2 is less than or equal to 270 degrees and less than or equal to 90 degreesi(1)When the angle is less than or equal to 270 degrees, starting from j to 2, the criterion F1 is determined according to the established grounding reactance line of the distance protection section ii(j)Zero-sequence reactance line criterion F2i(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of j th time of the distance protection j sectionZDFNi(j)The formula is as follows:
when the distance protection i section meets the condition that the angle is less than or equal to 90 degrees, F1i(j-1)F2 is less than or equal to 270 degrees and less than or equal to 90 degreesi(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)-0.5j-1*ZZDi
when the distance protection i section does not meet the condition that the angle is less than or equal to 90 degrees, F1i(j-1)F2 is less than or equal to 270 degrees or less than or equal to 90 degreesi(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)+0.5j-1*ZZDi
in the formula, i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10.
Further, the fourth calculating unit is used for calculating the phase-to-phase fault according to the fault phase-to-phase voltage when the line fault is the phase-to-phase fault
Figure BDA0001733494670000081
Fault phase current
Figure BDA0001733494670000082
And setting an impedance value ZZDFNi(1)Determining whether m-i distance protection segments starting from a distance protection i segment satisfy respective established interphase reactance line criterion F3i(1)If and only if m-i distance protection sections starting from the distance protection section i all satisfy the respective established interphase reactance line criterion F3i(1)Starting from j to 2, the criterion F3 is determined according to the established interphase reactance line of the distance protection i sectioni(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)The method comprises the following steps:
will fail the phase-to-phase voltage
Figure BDA0001733494670000083
Fault phase current
Figure BDA0001733494670000084
And setting an impedance value ZZDFNi(1)Respectively substituted into interphase reactance line criterion F3i(1)When the distance protection sections m-i from the distance protection section i meet the requirement of less than or equal to 90 degrees F3i(1)F3 is less than or equal to 270 degrees and less than or equal to 90 degreesi(1)When the angle is less than or equal to 270 degrees, finishing the distance measurement;
when m-i distance protection sections starting from the distance protection section i all meet the condition that the angle is less than or equal to 90 degrees and less than or equal to F3i(1)When the angle is less than or equal to 270 degrees, starting from j to 2, and according to the established interphase reactance line criterion F3 of the distance protection section ii(j)Distance-protecting section iConstant value ZZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)The formula is as follows:
when the distance protection i section meets the condition that the angle is less than or equal to 90 degrees, F3i(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)-0.5j-1*ZZDi
when the distance protection i section does not meet the condition that the angle is less than or equal to 90 degrees, F3i(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)+0.5j-1*ZZDi
in the formula, i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10.
Further, the fifth calculating unit calculates the voltage transformer transformation ratio N according to the preset impedance value B once per kilometer at the protection installation positionptCurrent transformer transformation ratio NctAnd the setting impedance value Z of the distance protection i section when j is equal to n-1ZDFNi(n-1)The formula for calculating the distance C between the line fault point and the protection installation is:
C＝(ZZDFNi(n-1)×(Npt/Nct))/B
wherein B is a set value of an impedance value per kilometer at a protection installation site, and N isptIs the transformation ratio of the voltage transformer, NctIs the current transformer transformation ratio, ZZDFNi(n-1)Is the setting impedance value Z of the distance protection i section when j is equal to n-1ZDFNi(n-1)。
The variable time-limit distance protection distance measurement method and the variable time-limit distance protection distance measurement device for the power grid line, provided by the technical scheme of the invention, firstly determine the distance protection section for carrying out the subsequent reactance line criterion through reactance line criteria under different fault conditions and by using the fixed value of each distance protection section as the initial setting impedance value of the distance protection section, then determine the setting impedance value for carrying out the next reactance line criterion of the distance protection section according to the calculation formula of the setting impedance value of the determined distance protection section, determine the final setting impedance value through multiple cycles, and finally determine the distance between a fault point and a protection installation position in variable time-limit distance protection according to the distance calculation formula. The time-limited distance protection and ranging method and the time-limited distance protection and ranging device for the power grid line can accurately position a fault point when the fault of the power grid line occurs in the range of the distance protection section, and the error is 1 e-3.
Drawings
A more complete understanding of exemplary embodiments of the present invention may be had by reference to the following drawings in which:
fig. 1 is a flow chart of a variable time-limited distance protection ranging method for a power grid line according to a preferred embodiment of the present invention;
fig. 2 is a schematic structural diagram of a variable time-limit distance-protection distance measuring device for a power grid line according to a preferred embodiment of the invention;
fig. 3 is a flowchart of a variable time-limit distance-protection ranging method for a power grid line according to another preferred embodiment of the present invention.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
Example one
Fig. 1 is a flowchart of a variable time-limit distance protection ranging method for a power grid line according to a preferred embodiment of the present invention. As shown in fig. 1, the variable time-limited distance protection ranging method 100 for power grid lines according to the present invention starts with step 101.
In step 101, instantaneous values of the secondary values of the three-phase voltage and current at a variable time-limited distance protection installation are collected.
In step 102, the three-phase voltage fundamental wave phasor value is determined according to the acquired instantaneous values of the secondary values of the three-phase voltage and the current
Figure BDA0001733494670000101
Sum current fundamental phasor value
Figure BDA0001733494670000105
And protecting the secondary value of the current fundamental wave phasor at the installation according to the variable time limit distance
Figure BDA0001733494670000106
Calculating zero sequence current
Figure BDA0001733494670000107
The three-phase voltage fundamental wave phasor value and the three-phase current fundamental wave phasor value are obtained by calculating the acquired instantaneous values of the secondary values of the three-phase voltage and the three-phase current by adopting a Fourier algorithm. Calculating zero sequence current
Figure BDA0001733494670000108
The formula of (1) is:
Figure BDA0001733494670000109
in step 103, the respective fixed values Z of m-1 distance protection segments at the protection installation site are setZDiRespectively as its setting impedance value ZZDFNi(j)A value when j is 1, wherein i is more than or equal to 1 and less than m, and m is a natural number more than 3;
in step 104, setting a primary impedance value B and a transformation ratio N of the voltage transformer at each kilometer of a protection installation positionptAnd current transformer transformation ratio NctAnd establishing a grounding reactance line criterion, a zero sequence reactance line criterion and an interphase reactance line criterion of each distance protection section, wherein:
the formula of the criterion of the grounding reactance line is as follows:
Figure BDA0001733494670000102
the formula of the zero-sequence reactance line criterion is as follows:
Figure BDA0001733494670000103
the formula of the criterion of the interphase reactance line is as follows:
Figure BDA0001733494670000104
in the formula, K is a preset zero sequence compensation coefficient,
Figure BDA0001733494670000111
is a fault phase voltage, the value of which is the voltage fundamental wave phase value of the fault phase,
Figure BDA0001733494670000112
is the voltage between the faulty phases, whose value is the difference of the phase values of the voltage fundamental wave between the faulty phases,
Figure BDA0001733494670000113
is a fault phase current, the value of which is the current fundamental wave phasor value of the fault phase,
Figure BDA0001733494670000114
is the fault phase current, whose value is the difference of the current fundamental wave phasor value of the fault phase,
Figure BDA00017334946700001110
is zero sequence current, ZZDFNi(j)Setting impedance of j time at the section i of distance protection, wherein i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10;
in step 105, determining whether the line fault is a single-phase fault or a phase-to-phase fault;
in step 106, when the line fault is a single phase fault, the phase voltage is based on the fault
Figure BDA0001733494670000115
Fault phase current
Figure BDA0001733494670000116
Setting an impedance value ZZDFNi(1)And zero sequence current
Figure BDA00017334946700001111
Determining whether m-i distance protection segments starting from a distance protection i segment satisfy respective established criterion of grounded reactance line F1i(1)Zero-sequence reactance line criterion F2i(1)If and only if m-i distance protection sections starting from the distance protection section i all satisfy the respective established criterion of grounded reactance line F1i(1)Zero-sequence reactance line criterion F2i(1)Starting from j-2, the established grounding reactance line criterion F1 of the distance protection i section is usedi(j)Zero-sequence reactance line criterion F2i(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)Wherein i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10;
in step 107, when the line fault is a phase-to-phase fault, the phase-to-phase voltage is determined according to the fault
Figure BDA0001733494670000117
Fault phase current
Figure BDA0001733494670000118
And setting an impedance value ZZDFNi(1)Determining whether m-i distance protection segments starting from a distance protection i segment satisfy respective established interphase reactance line criterion F3i(1)If and only if m-i distance protection sections starting from the distance protection section i all satisfy the respective established interphase reactance line criterion F3i(1)Starting from j to 2, the criterion F3 is determined according to the established interphase reactance line of the distance protection i sectioni(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)Wherein i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10;
in step 108, according to the preset impedance value B once per kilometer of the protection installation position and the transformation ratio N of the voltage transformerptCurrent transformer transformation ratio NctAnd the setting impedance value Z of the distance protection i section when j is equal to n-1ZDFNi(n-1)The distance C between the line fault point and the protection installation is calculated.
Preferably, when the line fault is a single-phase fault, the phase voltage is based on the fault
Figure BDA0001733494670000119
Fault phase current
Figure BDA0001733494670000125
Setting an impedance value ZZDFNi(1)And zero sequence current
Figure BDA0001733494670000126
Determining whether m-i distance protection segments starting from a distance protection i segment satisfy respective established criterion of grounded reactance line F1i(1)Zero-sequence reactance line criterion F2i(1)If and only if m-i distance protection sections starting from the distance protection section i all satisfy the respective established criterion of grounded reactance line F1i(1)Zero-sequence reactance line criterion F2i(1)Starting from j-2, the established grounding reactance line criterion F1 of the distance protection i section is usedi(j)Zero-sequence reactance line criterion F2i(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)The method comprises the following steps:
connecting the fault phase voltage
Figure BDA0001733494670000121
Fault phase current
Figure BDA0001733494670000122
And the determined setting impedance value ZZDFNi(1)And zero sequence current
Figure BDA0001733494670000127
Formula F1 substituted into criterion of grounding reactance linei(1)Formula F2 for criterion of zero-sequence reactance linei(1)When the distance protection sections m-i from the distance protection section i meet the requirement of less than or equal to 90 degrees F1i(1)F2 is less than or equal to 270 degrees and less than or equal to 90 degreesi(1)When the angle is less than or equal to 270 degrees, finishing the distance measurement;
when m-i distance protection sections starting from the distance protection section i all meet the condition that the angle is less than or equal to 90 degrees and less than or equal to F1i(1)F2 is less than or equal to 270 degrees and less than or equal to 90 degreesi(1)When the angle is less than or equal to 270 degrees, starting from j to 2, the criterion F1 is determined according to the established grounding reactance line of the distance protection section ii(j)Zero-sequence reactance line criterion F2i(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)The formula of (1) is:
when the distance protection i section meets the condition that the angle is less than or equal to 90 degrees, F1i(j-1)F2 is less than or equal to 270 degrees and less than or equal to 90 degreesi(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)-0.5j-1*ZZDi
when the distance protection i section does not meet the condition that the angle is less than or equal to 90 degrees, F1i(j-1)F2 is less than or equal to 270 degrees or less than or equal to 90 degreesi(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)+0.5j-1*ZZDi
in the formula, i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10.
Preferably, when the line fault is a phase-to-phase fault, the phase-to-phase voltage is based on the fault
Figure BDA0001733494670000123
Fault phase current
Figure BDA0001733494670000124
And settingImpedance value ZZDFNi(1)Determining whether m-i distance protection segments starting from a distance protection i segment satisfy respective established interphase reactance line criterion F3i(1)If and only if m-i distance protection sections starting from the distance protection section i all satisfy the respective established interphase reactance line criterion F3i(1)Starting from j to 2, the criterion F3 is determined according to the established interphase reactance line of the distance protection i sectioni(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)The method comprises the following steps:
will fail the phase-to-phase voltage
Figure BDA0001733494670000131
Fault phase current
Figure BDA0001733494670000132
And setting an impedance value ZZDFNi(1)Respectively substituted into interphase reactance line criterion F3i(1)When the distance protection sections m-i from the distance protection section i meet the requirement of less than or equal to 90 degrees F3i(1)F3 is less than or equal to 270 degrees and less than or equal to 90 degreesi(1)When the angle is less than or equal to 270 degrees, finishing the distance measurement;
when m-i distance protection sections starting from the distance protection section i all meet the condition that the angle is less than or equal to 90 degrees and less than or equal to F3i(1)When the angle is less than or equal to 270 degrees, starting from j to 2, and according to the established interphase reactance line criterion F3 of the distance protection section ii(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)The formula of (1) is:
when the distance protection i section meets the condition that the angle is less than or equal to 90 degrees, F3i(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)-0.5j-1*ZZDi
when the distance protection i section does not meet the condition that the angle is less than or equal to 90 degrees, F3i(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)+0.5j-1*ZZDi
in the formula, i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10.
Preferably, the transformation ratio N of the voltage transformer is determined according to the preset primary value B of impedance per kilometer at the protection installation positionptCurrent transformer transformation ratio NctAnd the setting impedance value Z of the distance protection i section when j is equal to n-1ZDFNi(n-1)The formula for calculating the distance C between the line fault point and the protection installation is:
C＝(ZZDFNi(n-1)×(Npt/Nct))/B
wherein B is a set value of an impedance value per kilometer at a protection installation site, and N isptIs the transformation ratio of the voltage transformer, NctIs the current transformer transformation ratio, ZZDFNi(n-1)Is the setting impedance value Z of the distance protection i section when j is equal to n-1ZDFNi(n-1)。
Fig. 2 is a schematic structural diagram of a variable time-limit distance-protection distance measuring device for a power grid line according to a preferred embodiment of the invention. As shown in fig. 2, the variable time-limit distance protection ranging apparatus 200 for a power grid line according to the present invention includes:
and the data acquisition unit 201 is used for acquiring instantaneous values of secondary values of three-phase voltage and current at the time-varying distance protection installation place.
A first calculation unit 202 for determining three-phase voltage fundamental wave phasor values according to instantaneous values of the collected three-phase voltage and current secondary values
Figure BDA0001733494670000141
Sum current fundamental phasor value
Figure BDA0001733494670000149
And protecting the secondary value of the current fundamental wave phasor at the installation according to the variable time limit distance
Figure BDA00017334946700001410
Calculating zero sequence current
Figure BDA00017334946700001411
Wherein, the three-phase voltage fundamental wave phasor value and the three-phase current fundamental wave phasor value are obtained by opposite samplingAnd the instantaneous values of the secondary values of the three-phase voltage and the current are obtained by calculation through a Fourier algorithm. Calculating zero sequence current
Figure BDA00017334946700001412
The formula of (1) is:
Figure BDA00017334946700001413
a second calculation unit 203 for calculating respective fixed values Z of m-1 distance protection segments at the protection installation siteZDiRespectively as its setting impedance value ZZDFNi(j)And j is 1, wherein i is more than or equal to 1 and less than m, and m is a natural number more than 3.
A parameter setting unit 204 for setting a primary value B of impedance per kilometer at a protection installation site and a transformation ratio N of the voltage transformerptAnd current transformer transformation ratio NctAnd establishing a grounding reactance line criterion, a zero sequence reactance line criterion and an interphase reactance line criterion of each distance protection section, wherein:
the formula of the criterion of the grounding reactance line is as follows:
Figure BDA0001733494670000142
the formula of the zero-sequence reactance line criterion is as follows:
Figure BDA0001733494670000143
the formula of the criterion of the interphase reactance line is as follows:
Figure BDA0001733494670000144
in the formula, K is a preset zero sequence compensation coefficient,
Figure BDA0001733494670000145
is a fault phase voltage of valueThe magnitude of the fundamental voltage wave of the failed phase,
Figure BDA0001733494670000146
is the voltage between the faulty phases, whose value is the difference of the phase values of the voltage fundamental wave between the faulty phases,
Figure BDA0001733494670000147
is a fault phase current, the value of which is the current fundamental wave phasor value of the fault phase,
Figure BDA0001733494670000148
is the fault phase current, the value of which is the difference of the phase values of the current fundamental wave of the fault phase, is the fault phase voltage, is the fault phase current,
Figure BDA00017334946700001414
is zero sequence current, ZZDFNi(i)The setting impedance of the ith time of the distance protection i section is shown, wherein i is more than or equal to 1 and less than m, i is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10.
A fault type determination unit 205 for determining whether the line fault is a single-phase fault or a phase-to-phase fault;
a third calculation unit 206 for, when the line fault is a single-phase fault, calculating a phase voltage according to the fault phase voltage
Figure BDA0001733494670000151
Fault phase current
Figure BDA0001733494670000152
Setting an impedance value ZZDFNi(1)And zero sequence current
Figure BDA0001733494670000157
Determining whether m-i distance protection segments starting from a distance protection i segment satisfy respective established criterion of grounded reactance line F1i(1)Zero-sequence reactance line criterion F2i(1)If and only if m-i distance protection sections starting from the distance protection section i all satisfy the respective established criterion of grounded reactance line F1i(1)And zero sequence reactance line criterionF2i(1)Starting from j-2, the established grounding reactance line criterion F1 of the distance protection i section is usedi(j)Zero-sequence reactance line criterion F2i(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)Wherein, 1 is less than or equal to i<J is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10;
a fourth calculation unit 207 for calculating a phase-to-phase voltage according to the fault when the line fault is a phase-to-phase fault
Figure BDA0001733494670000153
Fault phase current
Figure BDA0001733494670000154
And setting an impedance value ZZDFNi(1)Determining whether m-i distance protection segments starting from a distance protection i segment satisfy respective established interphase reactance line criterion F3i(1)If and only if m-i distance protection sections starting from the distance protection section i all satisfy the respective established interphase reactance line criterion F3i(1)Starting from j to 2, the criterion F3 is determined according to the established interphase reactance line of the distance protection i sectioni(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)Wherein, 1 is less than or equal to i<J is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10;
a fifth calculating unit 208 for calculating the transformation ratio N of the voltage transformer according to the preset impedance value B once per kilometer at the protection installation positionptCurrent transformer transformation ratio NctAnd the setting impedance value Z of the distance protection i section when j is equal to n-1ZDFNi(n-1)The distance C between the line fault point and the protection installation is calculated.
Preferably, the third calculating unit 206 calculates a phase voltage according to the fault phase when the line fault is a single-phase fault
Figure BDA0001733494670000155
Fault ofPhase current
Figure BDA0001733494670000156
Setting an impedance value ZZDFNi(1)And zero sequence current i0Determining whether m-i distance protection segments starting from a distance protection i segment satisfy respective established criterion of grounded reactance line F1i(1)Zero-sequence reactance line criterion F2i(1)If and only if m-i distance protection sections starting from the distance protection section i all satisfy the respective established criterion of grounded reactance line F1i(1)Zero-sequence reactance line criterion F2i(1)Starting from j-2, the established grounding reactance line criterion F1 of the distance protection i section is usedi(j)Zero-sequence reactance line criterion F2i(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)The method comprises the following steps:
connecting the fault phase voltage
Figure BDA0001733494670000161
Fault phase current
Figure BDA0001733494670000162
And the determined setting impedance value ZZDFNi(1)And zero sequence current
Figure BDA0001733494670000167
Formula F1 substituted into criterion of grounding reactance linei(1)Formula F2 for criterion of zero-sequence reactance linei(1)When the distance protection sections m-i from the distance protection section i meet the requirement of less than or equal to 90 degrees F1i(1)F2 is less than or equal to 270 degrees and less than or equal to 90 degreesi(1)When the angle is less than or equal to 270 degrees, finishing the distance measurement;
when m-i distance protection sections starting from the distance protection section i all meet the condition that the angle is less than or equal to 90 degrees and less than or equal to F1i(1)F2 is less than or equal to 270 degrees and less than or equal to 90 degreesi(1)When the angle is less than or equal to 270 degrees, starting from j to 2, the criterion F1 is determined according to the established grounding reactance line of the distance protection section ii(j)Zero-sequence reactance line criterion F2i(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating distance guaranteesJ-th setting impedance value Z of i-protecting sectionZDFNi(j)The formula of (1) is:
when the distance protection i section meets the condition that the angle is less than or equal to 90 degrees, F1i(j-1)F2 is less than or equal to 270 degrees and less than or equal to 90 degreesi(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)-0.5j-1*ZZDi
when the distance protection i section does not meet the condition that the angle is less than or equal to 90 degrees, F1i(j-1)F2 is less than or equal to 270 degrees or less than or equal to 90 degreesi(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)+0.5j-1*ZZDi
in the formula, i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10.
Preferably, the fourth calculating unit 207 is configured to calculate a phase-to-phase fault according to a fault phase-to-phase voltage when the line fault is a phase-to-phase fault
Figure BDA0001733494670000163
Fault phase current
Figure BDA0001733494670000164
And setting an impedance value ZZDFNi(1)Determining whether m-i distance protection segments starting from a distance protection i segment satisfy respective established interphase reactance line criterion F3i(1)If and only if m-i distance protection sections starting from the distance protection section i all satisfy the respective established interphase reactance line criterion F3i(1)Starting from j to 2, the criterion F3 is determined according to the established interphase reactance line of the distance protection i sectioni(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)The method comprises the following steps:
will fail the phase-to-phase voltage
Figure BDA0001733494670000165
Fault phase current
Figure BDA0001733494670000166
And setting an impedance value ZZDFNi(1)Are respectively provided withCriterion of substituting interphase reactance line F3i(1)When the distance protection sections m-i from the distance protection section i meet the requirement of less than or equal to 90 degrees F3i(1)F3 is less than or equal to 270 degrees and less than or equal to 90 degreesi(1)When the angle is less than or equal to 270 degrees, finishing the distance measurement;
when m-i distance protection sections starting from the distance protection section i all meet the condition that the angle is less than or equal to 90 degrees and less than or equal to F3i(1)When the angle is less than or equal to 270 degrees, starting from j to 2, and according to the established interphase reactance line criterion F3 of the distance protection section ii(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)The formula of (1) is:
when the distance protection i section meets the condition that the angle is less than or equal to 90 degrees, F3i(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)-0.5j-1*ZZDi
when the distance protection i section does not meet the condition that the angle is less than or equal to 90 degrees, F3i(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)+0.5j-1*ZZDi
in the formula, i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10.
Preferably, the fifth calculating unit 208 calculates the voltage transformer transformation ratio N according to the preset impedance value B once per kilometer at the protection installation siteptCurrent transformer transformation ratio NctAnd the setting impedance value Z of the distance protection i section when j is equal to n-1ZDFNi(n-1)The formula for calculating the distance C between the line fault point and the protection installation is:
C＝(ZZDFNi(n-1)×(Npt/Nct))/B
wherein B is a set value of an impedance value per kilometer at a protection installation site, and N isptIs the transformation ratio of the voltage transformer, NctIs the current transformer transformation ratio, ZZDFNi(n-1)Is the setting impedance value Z of the distance protection i section when j is equal to n-1ZDFNi(n-1)。
Example two
Fig. 3 is a flowchart of a variable time-limit distance-protection ranging method for a power grid line according to another preferred embodiment of the present invention. In the preferred embodiment, there are 3 distance guard segments in total. As shown in fig. 3, the variable time-limited distance protection ranging method 300 for power grid lines according to the present invention starts with step 301.
In step 301, instantaneous values of the secondary values of the three-phase voltage and current at the variable time-limited distance protection installation are collected.
In step 302, the three-phase voltage fundamental wave phasor value is determined according to the acquired instantaneous values of the secondary values of the three-phase voltage and the current
Figure BDA0001733494670000171
Sum current fundamental phasor value
Figure BDA0001733494670000172
And protecting the current fundamental wave phasor value at the installation according to the variable time limit distance
Figure BDA0001733494670000173
Calculating zero sequence current
Figure BDA0001733494670000174
The three-phase voltage fundamental wave phasor value and the three-phase current fundamental wave phasor value are obtained by calculating the acquired instantaneous values of the secondary values of the three-phase voltage and the three-phase current by adopting a Fourier algorithm. Calculating zero sequence current
Figure BDA00017334946700001812
The formula of (1) is:
Figure BDA00017334946700001813
in step 303, the respective fixed values Z of the 3 distance protection segments at the protection installation site are setZDiRespectively as its setting impedance value ZZDFNi(j)A value when j is 1, wherein 1. ltoreq. i<4；
In step 304, setting a primary impedance value B and a transformation ratio N of the voltage transformer at each kilometer of a protection installation positionptAnd current transformer transformation ratioNctAnd establishing a grounding reactance line criterion, a zero sequence reactance line criterion and an interphase reactance line criterion of 3 distance protection sections, wherein:
the formula of the criterion of the grounding reactance line is as follows:
Figure BDA0001733494670000181
the formula of the zero-sequence reactance line criterion is as follows:
Figure BDA0001733494670000182
the formula of the criterion of the interphase reactance line is as follows:
Figure BDA0001733494670000183
in the formula, K is a preset zero sequence compensation coefficient,
Figure BDA0001733494670000184
is a fault phase voltage, the value of which is the voltage fundamental wave phase value of the fault phase,
Figure BDA0001733494670000185
is the voltage between the faulty phases, whose value is the difference of the phase values of the voltage fundamental wave between the faulty phases,
Figure BDA0001733494670000186
is a fault phase current, the value of which is the current fundamental wave phasor value of the fault phase,
Figure BDA0001733494670000187
is the fault phase current, whose value is the difference of the current fundamental wave phasor value of the fault phase,
Figure BDA00017334946700001814
is zero sequence current, ZZDFNi(j)Is the setting impedance of j times of the i section of the distance protection, wherein i is more than or equal to 1 and less than4,2≤j<n, n is a natural number greater than 10;
in step 305, it is determined whether the line fault is a single-phase fault or a phase-to-phase fault;
in step 306, when the line fault is a single-phase fault, the fault phase is voltage-connected when the line fault is a single-phase fault
Figure BDA0001733494670000188
Fault phase current
Figure BDA0001733494670000189
And the determined setting impedance value ZZDFNi(1)And zero sequence current
Figure BDA00017334946700001815
Formula for respectively substituting into criterion of grounding reactance line of 3 distance protection sections
Figure BDA00017334946700001810
Figure BDA00017334946700001811
Figure BDA0001733494670000191
Formula for zero sequence reactance line criterion
Figure BDA0001733494670000192
Figure BDA0001733494670000193
Figure BDA0001733494670000194
F1 when 4-i distance protection sections which are not started from the distance protection section i all meet 90 degrees less than or equal toi(1)F2 is less than or equal to 270 degrees and less than or equal to 90 degreesi(1)When the angle is less than or equal to 270 degrees, finishing the distance measurement;
when the grounding reactance line criterion value and the zero sequence reactance line criterion value of 3 distance protection sections starting from the distance protection 1 section are both between 90 degrees and 270 degrees, starting from j-2, the established grounding reactance line criterion F1 is carried out according to the distance protection 1 section1(j)Zero-sequence reactance line criterion F21(j)Constant value Z of distance protection 1 sectionZD1And the j-1 th set impedance value ZZDFN1(j-1)Calculating the setting impedance value Z of the jth time of the distance protection 1 sectionZDFN1(j)The calculation formula is as follows:
when the distance between the section 1 and the protection section meets the condition that the angle is less than or equal to 90 degrees, F11(j-1)F2 is less than or equal to 270 degrees and less than or equal to 90 degrees1(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFN1(j)＝ZZDFN1(j-1)-0.5j-1*ZZD1
f1 when the distance protection 1 section does not meet 90 degrees ≦ F11(j-1)F2 is less than or equal to 270 degrees or less than or equal to 90 degrees1(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFN1(j)＝ZZDFN1(j-1)+0.5j-1*ZZD1
in the formula, j is more than or equal to 2 and less than n, and n is a natural number more than 10.
Or when the grounding reactance line criterion value and the zero sequence reactance line criterion value from the distance protection 2 section are both between 90 degrees and 270 degrees, starting from j to 2, according to the grounding reactance line criterion F1 established by the distance protection 2 section2(j)Zero-sequence reactance line criterion F22(j)Constant value Z of 2-stage distance protectionZD2And the j-1 th set impedance value ZZDFN2(j-1)Calculating the setting impedance value Z of the jth time of the 2-section distance protectionZDFN2(j)The formula of (1) is:
when the distance between the 2 sections of the protection meets the condition that the angle is less than or equal to 90 degrees, F12(j-1)F2 is less than or equal to 270 degrees and less than or equal to 90 degrees2(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFN2(j)＝ZZDFN2(j-1)-0.5j-1*ZZD2
when the distance protection 2 section does not meet 90 DEG≤F12(j-1)F2 is less than or equal to 270 degrees or less than or equal to 90 degrees2(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFN2(j)＝ZZDFN2(j-1)+0.5j-1*ZZD2
in the formula, j is more than or equal to 2 and less than n, and n is a natural number more than 10.
Or when the criterion value of the grounding reactance line of only 3 sections of distance protection and the criterion value of the zero sequence reactance line are both between 90 degrees and 270 degrees, starting from j to 2, according to the established criterion F1 of the grounding reactance line of 3 sections of distance protection3(j)Zero-sequence reactance line criterion F23(j)Fixed value Z of distance protection 3 sectionsZD3And the j-1 th set impedance value ZZDFN3(j-1)Calculating the j-th setting impedance value Z of the 3 sections of the distance protectionZDFN3(j)The formula of (1) is:
when the distance protection of 3 sections meets the condition that the angle is less than or equal to 90 degrees, F13(j-1)F2 is less than or equal to 270 degrees and less than or equal to 90 degrees3(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFN3(j)＝ZZDFN3(j-1)-0.5j-1*ZZD3
f1 when the distance protection of 3 sections does not meet 90 degrees ≦ F13(j-1)F2 is less than or equal to 270 degrees or less than or equal to 90 degrees3(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFN3(j)＝ZZDFN3(j-1)+0.5j-1*ZZD3
in the formula, j is more than or equal to 2 and less than n, and n is a natural number more than 10.
In step 307, when the line fault is a phase-to-phase fault, the fault phase-to-phase voltage is applied
Figure BDA0001733494670000201
Fault phase current
Figure BDA0001733494670000202
And setting an impedance value ZZDFNi(1)Substituting into the formula of the interphase reactance line criterion of 3 distance protection sections respectively:
Figure BDA0001733494670000203
Figure BDA0001733494670000204
Figure BDA0001733494670000205
f3 when 4-i distance protection sections which are not started from the distance protection section i all meet 90 degrees less than or equal toi(1)F3 is less than or equal to 270 degrees and less than or equal to 90 degreesi(1)When the angle is less than or equal to 270 degrees, finishing the distance measurement, wherein i is more than or equal to 1 and less than 4;
when 3 distance protection sections starting from the distance protection 1 section all satisfy 90 DEG ≦ F3i(1)When the angle is less than or equal to 270 degrees, starting from j to 2, and according to the established interphase reactance line criterion F3 of the distance protection 1 section1(j)Constant value Z of distance protection 1 sectionZD1And the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection 1 sectionZDFNi(j)The calculation formula is as follows:
when the distance between the section 1 and the protection section meets the condition that the angle is less than or equal to 90 degrees, F31(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFN1(j)＝ZZDFN1(j-1)-0.5j-1*ZZD1
f3 when the distance protection 1 section does not meet 90 degrees ≦ F31(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFN1(j)＝ZZDFN1(j-1)+0.5j-1*ZZD1
wherein j is more than or equal to 2 and less than n, and n is a natural number more than 10.
Or when 2 distance protection sections starting from the 2 distance protection sections all meet the condition of 90 degrees less than or equal to F3i(1)When the angle is less than or equal to 270 degrees, starting from j to 2, and according to the established interphase reactance line criterion F3 of the distance protection 2 sections2(j)Constant value Z of 2-stage distance protectionZD2And the j-1 th set impedance value ZZDFN2(j-1)Calculating the setting impedance value Z of the jth time of the 2-section distance protectionZDFN2(j)The calculation formula is as follows:
when the distance between the 2 sections of the protection meets the condition that the angle is less than or equal to 90 degrees, F32(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)-0.5j-1*ZZDi
f3 when the distance between the 2 sections of the protection is not more than 90 degrees2(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFN2(j)＝ZZDFN2(j-1)+0.5j-1*ZZD2
in the formula, j is more than or equal to 2 and less than n, and n is a natural number more than 10.
Or only 3 sections of distance protection meet the condition that the angle is less than or equal to 90 degrees and is less than or equal to F33(1)When the angle is less than or equal to 270 degrees, starting from j to 2, and according to the established interphase reactance line criterion F3 of the distance protection 3 sections3(j)Fixed value Z of distance protection 3 sectionsZD3And the j-1 th set impedance value ZZDFN3(j-1)Calculating the j-th setting impedance value Z of the 3 sections of the distance protectionZDFN3(j)The calculation formula is as follows:
when the distance protection of 3 sections meets the condition that the angle is less than or equal to 90 degrees, F33(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFN3(j)＝ZZDFN3(j-1)-0.5j-1*ZZD3
f3 when the distance protection of 3 sections does not meet 90 degrees ≦ F33(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFN3(j)＝ZZDFN3(j-1)+0.5j-1*ZZD3
in the formula, j is more than or equal to 2 and less than n, and n is a natural number more than 10.
In step 308, according to the preset impedance value B once per kilometer at the protection installation position and the transformation ratio N of the voltage transformerptCurrent transformer transformation ratio NctAnd the setting impedance value Z of the distance protection i section when j is equal to n-1ZDFNi(n-1)The distance C between the line fault point and the protection installation is calculated.
Preferably, the transformation ratio N of the voltage transformer is determined according to the preset primary value B of impedance per kilometer at the protection installation positionptCurrent transformer transformation ratio NctAnd the setting impedance value Z of the distance protection i section when j is equal to n-1ZDFNi(n-1)The formula for calculating the distance C between the line fault point and the protection installation is:
C＝(ZZDFNi(n-1)×(Npt/Nct))/B
wherein B is a set value of an impedance value per kilometer at a protection installation site, and N isptIs the transformation ratio of the voltage transformer, NctIs the current transformer transformation ratio, ZZDFNi(n-1)Is the setting impedance value Z of the distance protection i section when j is equal to n-1ZDFNi(n-1)。
The structure of the time-limited distance protection measuring device for the power grid line in the preferred embodiment is the same as that in the first embodiment, and is not described here.
The invention has been described with reference to a few embodiments. However, other embodiments of the invention than the one disclosed above are equally possible within the scope of the invention, as would be apparent to a person skilled in the art from the appended patent claims.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the [ device, component, etc ]" are to be interpreted openly as referring to at least one instance of said device, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

Claims (10)

1. A variable time-limit distance protection ranging method for a power grid line, the method comprising:
determining whether the line fault is a single-phase fault or a phase-to-phase fault;
when the line fault is a single-phase fault, the phase voltage is changed according to the fault
Figure FDA0001733494660000011
Fault phase current
Figure FDA0001733494660000012
Setting an impedance value ZZDFNi(1)And zero sequence current
Figure FDA0001733494660000013
Determining slave distance guaranteesWhether the fixed values of m-i distance protection sections at the beginning of the protection section I meet the respectively established grounding reactance line criterion F1i(1)Zero-sequence reactance line criterion F2i(1)If and only if m-i distance protection sections starting from the distance protection i section all satisfy the respectively established criterion of grounded reactance line F1i(1)Zero-sequence reactance line criterion F2i(1)Starting from j-2, the established grounding reactance line criterion F1 of the distance protection i section is usedi(j)Zero-sequence reactance line criterion F2i(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)Wherein i is more than or equal to 1 and less than m, and j is more than or equal to 2<n, m is a natural number greater than 3, n is a natural number greater than 10;
when the line fault is a phase-to-phase fault, the phase-to-phase voltage is determined according to the fault
Figure FDA0001733494660000014
Fault phase current
Figure FDA0001733494660000015
And setting an impedance value ZZDFNi(1)Determining whether m-i distance protection segments starting from a distance protection i segment satisfy respective established interphase reactance line criterion F3i(1)If and only if m-i distance protection sections starting from the distance protection section i all satisfy the respective established interphase reactance line criterion F3i(1)Starting from j to 2, the criterion F3 is determined according to the established interphase reactance line of the distance protection i sectioni(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)Wherein i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10;
according to a preset impedance value B of each kilometer of a protection installation position and a voltage transformer transformation ratio NptCurrent transformer transformation ratio NctAnd the setting impedance value Z of the distance protection i section when j is equal to n-1ZDFNi(n-1)The distance C between the line fault point and the protection installation is calculated.
2. The method of claim 1, prior to determining whether the line fault is a single-phase fault or a phase-to-phase fault, comprising:
collecting instantaneous values of secondary values of three-phase voltage and current at a variable time-limit distance protection installation position;
determining the three-phase voltage fundamental wave phasor value according to the acquired instantaneous values of the secondary values of the three-phase voltage and the current
Figure FDA0001733494660000021
Sum current fundamental phasor value
Figure FDA0001733494660000022
And protecting the current fundamental wave phasor value at the installation according to the variable time limit distance
Figure FDA0001733494660000023
Calculating zero sequence current
Figure FDA0001733494660000024
And setting the fault phase voltage fundamental phasor as
Figure FDA0001733494660000025
The value of the phase current is equal to the voltage fundamental wave phasor value of the faulted phase, and the fault phase current fundamental component is set
Figure FDA0001733494660000026
A current fundamental phasor value equal to the faulted phase;
the respective fixed value Z of m-1 distance protection sections at the protection installation positionZDiRespectively as its setting impedance value ZZDFNi(j)A value when j is 1, wherein i is more than or equal to 1 and less than m, and m is a natural number more than 3;
setting a primary impedance value B and a transformation ratio N of the voltage transformer at a protection installation position per kilometerptAnd current transformer transformation ratio NctA value of (d);
establishing a grounding reactance line criterion, a zero sequence reactance line criterion and an interphase reactance line criterion of each distance protection section, wherein:
the formula of the criterion of the grounding reactance line is as follows:
Figure FDA0001733494660000027
the formula of the zero-sequence reactance line criterion is as follows:
Figure FDA0001733494660000028
the formula of the criterion of the interphase reactance line is as follows:
Figure FDA0001733494660000029
in the formula, K is a preset zero sequence compensation coefficient,
Figure FDA00017334946600000210
is a fault phase voltage, the value of which is the voltage fundamental wave phase value of the fault phase,
Figure FDA00017334946600000211
is the voltage between the faulty phases, whose value is the difference of the phase values of the voltage fundamental wave between the faulty phases,
Figure FDA00017334946600000212
is a fault phase current, the value of which is the current fundamental wave phasor value of the fault phase,
Figure FDA00017334946600000213
is the fault phase current, whose value is the difference of the current fundamental wave phasor value of the fault phase,
Figure FDA00017334946600000214
is zero sequence current, ZZDFNi(j)The setting impedance of the jth time of the i section of the distance protection is represented, wherein i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number which is more than 3, and n is a natural number which is more than 10.
3. The method of claim 2, wherein when the line fault is a single phase fault, the phase voltage is based on the fault phase
Figure FDA00017334946600000215
Fault phase current
Figure FDA00017334946600000216
Setting an impedance value ZZDFNi(1)And zero sequence current
Figure FDA00017334946600000217
Determining whether m-i distance protection segments starting from a distance protection i segment satisfy respective established criterion of grounded reactance line F1i(1)Zero-sequence reactance line criterion F2i(1)If and only if m-i distance protection sections starting from the distance protection section i all satisfy the respective established criterion of grounded reactance line F1i(1)Zero-sequence reactance line criterion F2i(1)Starting from j-2, the established grounding reactance line criterion F1 of the distance protection i section is usedi(j)Zero-sequence reactance line criterion F2i(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)The method comprises the following steps:
connecting the fault phase voltage
Figure FDA0001733494660000031
Fault phase current
Figure FDA0001733494660000032
And the determined setting impedance value ZZDFNi(1)And zero sequence current
Figure FDA0001733494660000033
Respectively substitute forFormula F1 of criterion of grounding reactance linei(1)Formula F2 for criterion of zero-sequence reactance linei(1)When the distance protection sections m-i from the distance protection section i meet the requirement of less than or equal to 90 degrees F1i(1)F2 is less than or equal to 270 degrees and less than or equal to 90 degreesi(1)When the angle is less than or equal to 270 degrees, finishing the distance measurement;
when m-i distance protection sections starting from the distance protection section i all meet the condition that the angle is less than or equal to 90 degrees and less than or equal to F1i(1)F2 is less than or equal to 270 degrees and less than or equal to 90 degreesi(1)When the angle is less than or equal to 270 degrees, starting from j to 2, the criterion F1 is determined according to the established grounding reactance line of the distance protection section ii(j)Zero-sequence reactance line criterion F2i(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)The formula is as follows:
when the distance protection i section meets the condition that the angle is less than or equal to 90 degrees, F1i(j-1)F2 is less than or equal to 270 degrees and less than or equal to 90 degreesi(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)-0.5j-1*ZZDi
when the distance protection i section does not meet the condition that the angle is less than or equal to 90 degrees, F1i(j-1)F2 is less than or equal to 270 degrees or less than or equal to 90 degreesi(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)+0.5j-1*ZZDi
in the formula, i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10.
4. A method according to claim 2, characterized in that when the line fault is a phase-to-phase fault, the phase-to-phase voltage is dependent on the fault
Figure FDA0001733494660000034
Fault phase current
Figure FDA0001733494660000035
And setting an impedance value ZZDFNi(1)Determining whether m-i distance protection segments starting from a distance protection i segment satisfy respective established interphase reactance line criterion F3i(1)If and only if from distanceM-i distance protection sections starting from the protection section i all meet the established criterion of interphase reactance line F3i(1)Starting from j to 2, the criterion F3 is determined according to the established interphase reactance line of the distance protection i sectioni(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)The method comprises the following steps:
will fail the phase-to-phase voltage
Figure FDA0001733494660000041
Fault phase current
Figure FDA0001733494660000042
And setting an impedance value ZZDFNi(1)Respectively substituted into interphase reactance line criterion F3i(1)When the distance protection sections m-i from the distance protection section i meet the requirement of less than or equal to 90 degrees F3i(1)F3 is less than or equal to 270 degrees and less than or equal to 90 degreesi(1)When the angle is less than or equal to 270 degrees, finishing the distance measurement;
when m-i distance protection sections starting from the distance protection section i all meet the condition that the angle is less than or equal to 90 degrees and less than or equal to F3i(1)When the angle is less than or equal to 270 degrees, starting from j to 2, and according to the established interphase reactance line criterion F3 of the distance protection section ii(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)The formula is as follows:
when the distance protection i section meets the condition that the angle is less than or equal to 90 degrees, F3i(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)-0.5j-1*ZZDi
when the distance protection i section does not meet the condition that the angle is less than or equal to 90 degrees, F3i(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)+0.5j-1*ZZDi
in the formula, i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10.
5. The method according to claim 3 or 4,the method is characterized in that the transformation ratio N of the voltage transformer is determined according to a preset primary impedance value B per kilometer of a protection installation positionptCurrent transformer transformation ratio NctAnd the setting impedance value Z of the distance protection i section when j is equal to n-1ZDFNi(n-1)The formula for calculating the distance C between the line fault point and the protection installation is:
C＝(ZZDFNi(n-1)×(Npt/Nct))/B
wherein B is a set value of an impedance value per kilometer at a protection installation site, and N isptIs the transformation ratio of the voltage transformer, NctIs the current transformer transformation ratio, ZZDFNi(n-1)Is the setting impedance value Z of the distance protection i section when j is equal to n-1ZDFNi(n-1)。
6. A variable time-limited distance protection ranging apparatus for a power grid line, the apparatus comprising:
a fault type determination unit for determining whether the line fault is a single-phase fault or a phase-to-phase fault;
a third calculation unit for, when the line fault is a single-phase fault, calculating a phase voltage according to the fault
Figure FDA0001733494660000043
Fault phase current
Figure FDA0001733494660000044
Setting an impedance value ZZDFNi(1)And zero sequence current
Figure FDA0001733494660000045
Determining whether m-i distance protection segments starting from a distance protection i segment satisfy respective established criterion of grounded reactance line F1i(1)Zero-sequence reactance line criterion F2i(1)If and only if m-i distance protection sections starting from the distance protection section i all satisfy the respective established criterion of grounded reactance line F1i(1)Zero-sequence reactance line criterion F2i(1)Starting from j-2, the established grounding reactance line criterion F1 of the distance protection i section is usedi(j)And zeroSequence reactance line criterion F2i(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)Wherein i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10;
a fourth calculation unit for calculating a phase-to-phase voltage according to the fault when the line fault is a phase-to-phase fault
Figure FDA0001733494660000051
Fault phase current
Figure FDA0001733494660000052
And setting an impedance value ZZDFNi(1)Determining whether n-i distance protection segments starting from a distance protection i segment satisfy respective established interphase reactance line criterion F3i(1)If and only if m-i distance protection sections starting from the distance protection section i all satisfy the respective established interphase reactance line criterion F3i(1)Starting from j to 2, the criterion F3 is determined according to the established interphase reactance line of the distance protection i sectioni(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)Wherein i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10;
a fifth calculating unit for calculating the transformation ratio N of the voltage transformer according to the preset primary value B of the impedance per kilometer at the protection installation positionptCurrent transformer transformation ratio NctAnd the setting impedance value Z of the distance protection i section when j is equal to n-1ZDFNi(n-1)The distance C between the line fault point and the protection installation is calculated.
7. The apparatus of claim 6, further comprising:
the data acquisition unit is used for acquiring instantaneous values of secondary values of three-phase voltage and current at a variable time-limit distance protection installation position;
a first calculation unit whichUsed for determining the three-phase voltage fundamental wave phasor value according to the acquired instantaneous values of the three-phase voltage and current secondary values
Figure FDA0001733494660000053
Sum current fundamental phasor value
Figure FDA0001733494660000054
And protecting the secondary value of the current fundamental wave phasor at the installation according to the variable time limit distance
Figure FDA0001733494660000055
Calculating zero sequence current
Figure FDA0001733494660000056
A second calculation unit for calculating a fixed value Z for each of the m-1 distance protection segments at the protection installation siteZDiRespectively as its setting impedance value ZZDFNi(j)A value when j is 1, wherein i is more than or equal to 1 and less than m, and m is a natural number more than 3;
a parameter setting unit for setting a primary value B of impedance per kilometer at a protection installation site and a transformation ratio N of the voltage transformerptAnd current transformer transformation ratio NctAnd establishing a grounding reactance line criterion, a zero sequence reactance line criterion and an interphase reactance line criterion of each distance protection section, wherein:
the formula of the criterion of the grounding reactance line is as follows:
Figure FDA0001733494660000061
the formula of the zero-sequence reactance line criterion is as follows:
Figure FDA0001733494660000062
the formula of the criterion of the interphase reactance line is as follows:
Figure FDA0001733494660000063
in the formula, K is a preset zero sequence compensation coefficient,
Figure FDA0001733494660000064
is a fault phase voltage, the value of which is the voltage fundamental wave phase value of the fault phase,
Figure FDA0001733494660000065
is the voltage between the faulty phases, whose value is the difference of the phase values of the voltage fundamental wave between the faulty phases,
Figure FDA0001733494660000066
is a fault phase current, the value of which is the current fundamental wave phasor value of the fault phase,
Figure FDA0001733494660000067
is the fault phase current, whose value is the difference of the current fundamental wave phasor value of the fault phase,
Figure FDA0001733494660000068
is zero sequence current, ZZDFNi(j)The setting impedance of the jth time of the i section of the distance protection is represented, wherein i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number which is more than 3, and n is a natural number which is more than 10.
8. The apparatus of claim 7, wherein the third computing unit is configured to determine a faulty phase voltage when the line fault is a single-phase fault
Figure FDA0001733494660000069
Fault phase current
Figure FDA00017334946600000610
Setting an impedance value ZZDFNi(1)And zero sequence current
Figure FDA00017334946600000611
Determining whether m-i distance protection segments starting from a distance protection i segment satisfy respective established criterion of grounded reactance line F1i(1)Zero-sequence reactance line criterion F2i(1)If and only if m-i distance protection sections starting from the distance protection section i all satisfy the respective established criterion of grounded reactance line F1i(1)Zero-sequence reactance line criterion F2i(1)Starting from j-2, the established grounding reactance line criterion F1 of the distance protection i section is usedi(j)Zero-sequence reactance line criterion F2i(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)The method comprises the following steps:
connecting the fault phase voltage
Figure FDA00017334946600000612
Fault phase current
Figure FDA00017334946600000613
And the determined setting impedance value ZZDFNi(1)And zero sequence current
Figure FDA0001733494660000071
Formula F1 substituted into criterion of grounding reactance linei(1)Formula F2 for criterion of zero-sequence reactance linei(1)When the distance protection sections m-i from the distance protection section i meet the requirement of less than or equal to 90 degrees F1i(1)F2 is less than or equal to 270 degrees and less than or equal to 90 degreesi(1)When the angle is less than or equal to 270 degrees, finishing the distance measurement;
when m-i distance protection sections starting from the distance protection section i all meet the condition that the angle is less than or equal to 90 degrees and less than or equal to F1i(1)F2 is less than or equal to 270 degrees and less than or equal to 90 degreesi(1)When the angle is less than or equal to 270 degrees, starting from j to 2, the criterion F1 is determined according to the established grounding reactance line of the distance protection section ii(j)Zero-sequence reactance line criterion F2i(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)The formula is as follows:
when the distance protection i section meets the condition that the angle is less than or equal to 90 degrees, F1i(j-1)F2 is less than or equal to 270 degrees and less than or equal to 90 degreesi(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)-0.5j-1*ZZDi
when the distance protection i section does not meet the condition that the angle is less than or equal to 90 degrees, F1i(j-1)F2 is less than or equal to 270 degrees or less than or equal to 90 degreesi(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)+0.5j-1*ZZDi
in the formula, i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10.
9. The apparatus according to claim 7, wherein the fourth calculating unit is configured to calculate the line fault as a phase-to-phase fault according to a fault phase-to-phase voltage
Figure FDA0001733494660000072
Fault phase current
Figure FDA0001733494660000073
And setting an impedance value ZZDFNi(1)Determining whether m-i distance protection segments starting from a distance protection i segment satisfy respective established interphase reactance line criterion F3i(1)If and only if m-i distance protection sections starting from the distance protection section i all satisfy the respective established interphase reactance line criterion F3i(1)Starting from j to 2, the criterion F3 is determined according to the established interphase reactance line of the distance protection i sectioni(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)The method comprises the following steps:
will fail the phase-to-phase voltage
Figure FDA0001733494660000074
Fault phase current
Figure FDA0001733494660000075
And setting an impedance value ZZDFNi(1)Respectively substituted into interphase reactance line criterion F3i(1)When the distance protection sections m-i from the distance protection section i meet the requirement of less than or equal to 90 degrees F3i(1)F3 is less than or equal to 270 degrees and less than or equal to 90 degreesi(1)When the angle is less than or equal to 270 degrees, finishing the distance measurement;
when m-i distance protection sections starting from the distance protection section i all meet the condition that the angle is less than or equal to 90 degrees and less than or equal to F3i(1)When the angle is less than or equal to 270 degrees, starting from j to 2, and according to the established interphase reactance line criterion F3 of the distance protection section ii(j)Constant value Z of distance protection i sectionZDiAnd the j-1 th set impedance value ZZDFNi(j-1)Calculating the setting impedance value Z of the jth time of the distance protection i sectionZDFNi(j)The formula of (1) is:
when the distance protection i section meets the condition that the angle is less than or equal to 90 degrees, F3i(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)-0.5j-1*ZZDi
when the distance protection i section does not meet the condition that the angle is less than or equal to 90 degrees, F3i(j-1)When the temperature is less than or equal to 270 ℃,
ZZDFNi(j)＝ZZDFNi(j-1)+0.5j-1*ZZDi
in the formula, i is more than or equal to 1 and less than m, j is more than or equal to 2 and less than n, m is a natural number more than 3, and n is a natural number more than 10.
10. The apparatus according to claim 8 or 9, wherein the fifth calculating unit calculates the voltage transformer transformation ratio N according to the preset impedance value B once per kilometer at the protection installation siteptCurrent transformer transformation ratio NctAnd the setting impedance value Z of the distance protection i section when j is equal to n-1ZDFNi(n-1)The formula for calculating the distance C between the line fault point and the protection installation is:
C＝(ZZDFNi(n-1)×(Npt/Nct))/B
wherein B is a set value of an impedance value per kilometer at a protection installation site, and N isptIs the transformation ratio of the voltage transformer, NctIs the current transformer transformation ratio, ZZDFNi(n-1)Is the setting impedance value Z of the distance protection i section when j is equal to n-1ZDFNi(n-1)。
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