CN112271706A - Current differential protection method suitable for power transmission line accessed by multiple types of shunt reactors - Google Patents

Current differential protection method suitable for power transmission line accessed by multiple types of shunt reactors Download PDF

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Publication number
CN112271706A
CN112271706A CN202010958684.1A CN202010958684A CN112271706A CN 112271706 A CN112271706 A CN 112271706A CN 202010958684 A CN202010958684 A CN 202010958684A CN 112271706 A CN112271706 A CN 112271706A
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current
transmission line
differential
power transmission
protection
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CN112271706B (en
Inventor
吴通华
姚刚
洪丰
陈国洲
滕贤亮
郑玉平
郑小江
江源
刘天明
孙志攀
王威威
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NARI Group Corp
Nari Technology Co Ltd
NARI Nanjing Control System Co Ltd
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NARI Group Corp
Nari Technology Co Ltd
NARI Nanjing Control System Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/261—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations
    • H02H7/262—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations involving transmissions of switching or blocking orders
    • 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
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/261—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations
    • H02H7/263—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations involving transmissions of measured values
    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/30—Reactive power compensation

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  • General Physics & Mathematics (AREA)
  • Emergency Protection Circuit Devices (AREA)

Abstract

The invention discloses a current differential protection method of a power transmission line suitable for access of multiple types of shunt reactors, which comprises the steps of obtaining time domain capacitance current of the power transmission line and secondary instantaneous current of the shunt reactor; superposing the time domain capacitance current and the secondary instantaneous current to obtain a compensation value of the distributed capacitance current of the power transmission line; substituting the compensation value of the distributed capacitance current and the sampling values of the protection installation positions at two sides of the power transmission line into a complete compensation differential current calculation formula to obtain complete compensation differential current; substituting sampling values at the protective installation positions at two sides of the power transmission line into a non-compensated differential current calculation formula to obtain non-compensated differential current; judging whether to start the fully compensated current differential protection or not based on the fully compensated differential current and a preset first action equation; and judging whether to start the uncompensated current differential protection or not based on the uncompensated differential current and a preset second action equation. The invention can improve the sensitivity, reliability and action accuracy of the current differential protection of the power transmission line.

Description

Current differential protection method suitable for power transmission line accessed by multiple types of shunt reactors
Technical Field
The invention particularly relates to a current differential protection method suitable for a power transmission line accessed by multiple types of shunt reactors.
Background
Shunt reactors are important devices for compensating capacitive reactive power and limiting line overvoltage in ultra (ultra) high voltage transmission systems. At present, the capacity of the most widely applied shunt reactor is fixed, and when a system runs under heavy load, the line voltage can be reduced and the power grid loss can be increased. Compared with a parallel reactor with fixed capacity, the parallel reactor with controllable capacity is flexible to control, can effectively coordinate contradictions between overvoltage limitation and reactive power regulation of a power transmission system, and has wide engineering application prospect. According to different composition principles, the capacity-controllable shunt reactor can be divided into a magnetic control type and a valve control type. The former is based on the magnetic saturation principle and can be continuously adjusted, but the response speed is slow and the harmonic content is high. The high-impedance transformer based on the principle of the high-impedance transformer can only be adjusted in a grading mode, but is high in response speed, low in harmonic content, low in self loss and obvious in technical advantage.
The distributed capacitance current flows out of the inside of the power transmission line for the current differential protection of the ultra (ultra) high-voltage power transmission line to form differential current, so that the compensation of the distributed capacitance current is the key for influencing the correctness of the current differential protection action. When an extra (special) high-voltage long line has an external fault, the external fault is removed and the line is charged in a no-load mode, the amplitude of the current of the capacitor is large, and therefore the reliability of differential protection is affected.
In the existing power transmission line current differential protection method applied to the valve-controlled capacity-controllable shunt reactor, the capacitance current compensation is to calculate the current reactor impedance value by obtaining the real-time gear information of the capacity of the shunt reactor to solve the current substituting calculation flowing through the reactor. This approach places high demands on the real-time performance of the gears that acquire capacity: the capacity adjustment of the capacity-controllable shunt reactor is a transient process lasting for hundreds of milliseconds, and the gear information is a switching value signal and cannot reflect the capacity adjustment change, so that the problem that the gear information does not correspond to the actual capacity can be caused in the adjustment process, and the capacitance current cannot be accurately compensated, so that the sensitivity and the reliability of the current differential protection of the power transmission line are influenced. And at present, no applicable current differential protection method for the power transmission line exists for the magnetically controlled capacity-controllable shunt reactor. If the current flowing through the reactor is solved by using a fixed impedance value for compensation, the distributed capacitance current compensation effect is not good, and the current differential protection action is easy to be incorrect in the transient process.
Disclosure of Invention
Aiming at the problems, the invention provides a current differential protection method of a power transmission line which is suitable for connecting multiple types of shunt reactors, which can improve the sensitivity, reliability and action accuracy of the current differential protection of the power transmission line.
In order to achieve the technical purpose and achieve the technical effects, the invention is realized by the following technical scheme:
the invention provides a current differential protection method suitable for a power transmission line accessed by a shunt reactor, which comprises the following steps:
acquiring time domain capacitance current of the power transmission line and secondary instantaneous current of a shunt reactor connected with the power transmission line;
after the time domain capacitance current and the secondary instantaneous current of the shunt reactor are superposed, a compensation value of the distributed capacitance current of the power transmission line is obtained;
substituting the compensation value of the distributed capacitance current and the sampling values of the protection installation positions at two sides of the power transmission line into a complete compensation differential current calculation formula, calculating a complete compensation differential current, and calculating a complete compensation differential current;
substituting sampling values at the protective installation positions at two sides of the power transmission line into an uncompensated differential current calculation formula to calculate uncompensated differential current;
judging whether to start the fully compensated current differential protection or not based on the fully compensated differential current and a preset first action equation;
and judging whether to start the uncompensated current differential protection or not based on the uncompensated differential current and a preset second action equation.
Optionally, the calculation formula of the compensation value of the distributed capacitance current is:
Figure BDA0002679517160000021
in the formula (I), the compound is shown in the specification,
Figure BDA0002679517160000022
for the compensation value of the distributed capacitance current,
Figure BDA0002679517160000023
is a parallel reactanceThe head end of the device carries secondary instantaneous current of A phase or B phase or C phase,
Figure BDA0002679517160000024
is the time domain capacitance current of the transmission line, C transmission line concentration parameter equivalent capacitance value, ucIs the transmission line voltage.
Optionally, the calculation formula of the fully compensated differential current is:
Figure BDA0002679517160000025
in the formula (I), the compound is shown in the specification,
Figure BDA0002679517160000026
it is shown that the differential current is fully compensated,
Figure BDA0002679517160000027
representing the current sampling value of the protection installation at one side of the transmission line,
Figure BDA0002679517160000028
representing the current sampling value of the protection installation at the other side of the transmission line,
Figure BDA0002679517160000029
represents the compensation value of the distributed capacitance current on the transmission line side,
Figure BDA00026795171600000210
uMCwhich represents the voltage on one side of the transmission line,
Figure BDA00026795171600000211
represents the secondary instantaneous value of the head end of the shunt reactor on one side of the transmission line,
Figure BDA00026795171600000212
a compensation value representing the distributed capacitance current on the other side of the transmission line,
Figure BDA00026795171600000213
uNCrepresenting the voltage on the other side of the transmission line,
Figure BDA00026795171600000214
represents the secondary instantaneous value of the head end of the shunt reactor at the other side of the transmission line,
Figure BDA00026795171600000215
indicating A, B or phase C.
Optionally, the first action equation is:
Figure BDA0002679517160000031
in the formula ITHRepresenting the action threshold of the fully compensated differential current protection,
Figure BDA0002679517160000032
indicating a fully compensated braking current and k a rate braking coefficient.
Optionally, the formula for calculating the uncompensated differential current is as follows:
Figure BDA0002679517160000033
in the formula (I), the compound is shown in the specification,
Figure BDA0002679517160000034
representing the current sampling value of the protection installation at one side of the transmission line,
Figure BDA0002679517160000035
representing the current sampling value of the protection installation at the other side of the transmission line,
Figure BDA0002679517160000036
representing an uncompensated differential current.
Optionally, the second action equation is:
Figure BDA0002679517160000037
in the formula ITH' represents the action threshold of the uncompensated differential current protection, which is 1.5 times of the action threshold of the fully compensated differential current protection, k is the ratio brake coefficient,
Figure BDA0002679517160000038
representing an uncompensated differential current.
Optionally, the method further comprises determining the fault location based on the operating states of the fully compensated current differential protection and the uncompensated current differential protection.
Optionally, when both the uncompensated current differential protection and the fully compensated current differential protection act, it is determined that the fault is located inside the power transmission line.
Alternatively, when the uncompensated current differential protection is not operated and the fully compensated current differential protection is not operated, it is determined that the fault is located inside the parallel reactor.
Optionally, when the uncompensated current differential protection and the fully compensated current differential protection are not active, it is determined that the fault is located outside the power transmission line.
Optionally, the sampling values of the protection installation places on both sides of the power transmission line are collected by an ac transformer, and the method further includes:
when the AC transformer is judged to be abnormal, the complete compensation current differential protection is controlled to instantly quit the differential calculation and logic execution, and the differential calculation and logic execution is controlled without the compensation current differential protection.
Compared with the prior art, the invention has the beneficial effects that:
the invention effectively solves the problem that the traditional power transmission line current differential protection method is not suitable for a power transmission system accessed by a capacity-controllable parallel reactor, and improves the sensitivity, reliability and action accuracy of the power transmission line current differential protection.
Drawings
In order that the present disclosure may be more readily and clearly understood, reference is now made to the following detailed description of the present disclosure taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a logic diagram of a workflow provided by an embodiment of the present invention;
FIG. 2 is a comparison of distributed capacitance current compensation effects of a conventional fixed compensation method and a full compensation method provided by the present invention during a transient state of capacity switching of a controllable shunt reactor;
FIG. 3 is a comparison of distributed capacitance current compensation effects of a conventional fixed compensation method and a full compensation method provided by the present invention during an out-of-range fault occurring during a transient switching process of a controllable shunt reactor capacity;
FIG. 4 shows the fully compensated differential current and the uncompensated differential current of the present invention when an internal failure occurs in a power transmission line during a transient state of capacity switching of a controllable parallel reactor;
FIG. 5 is a diagram of differential current with full compensation and differential current without compensation according to the present invention when an external fault occurs in a power transmission line during a transient state of capacity switching of a controllable parallel reactor;
FIG. 6 is a diagram of fully compensated differential current versus uncompensated differential current for a shunt reactor internal fault during a transient state of controllable shunt reactor capacity switching according to the present invention;
fig. 7 shows specific ranges of the internal faults of the power transmission line and the shunt reactor mentioned in the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of the invention.
The following detailed description of the principles of the invention is provided in connection with the accompanying drawings.
The invention provides a current differential protection method suitable for a power transmission line accessed by a shunt reactor, which specifically comprises the following steps:
(1) acquiring time domain capacitance current of the power transmission line and secondary instantaneous current of a shunt reactor connected with the power transmission line;
(2) after the time domain capacitance current and the secondary instantaneous current of the shunt reactor are superposed, a compensation value of the distributed capacitance current of the power transmission line is obtained;
(3) and substituting the compensation value of the distributed capacitance current and the sampling values of the protection installation positions at two sides of the power transmission line into a complete compensation differential current calculation formula, calculating a complete compensation differential current, and calculating the complete compensation differential current. Substituting sampling values at the protective installation positions at two sides of the power transmission line into an uncompensated differential current calculation formula to calculate uncompensated differential current;
(4) judging whether to start the fully compensated current differential protection or not based on the fully compensated differential current and a preset first action equation;
(5) and judging whether to start the uncompensated current differential protection or not based on the uncompensated differential current and a preset second action equation.
The calculation formula of the compensation value of the distributed capacitance current is as follows:
Figure BDA0002679517160000051
in the formula IφcompFor the compensation value of the distributed capacitance current,
Figure BDA0002679517160000052
a-phase or B-phase or C-phase secondary instantaneous current is provided at the head end of the parallel reactor, and the current at the head end of the reactor is specified to flow to the reactor in a positive direction;
Figure BDA0002679517160000053
is the time domain capacitance current of the transmission line, C transmission line concentration parameter equivalent capacitance value, ucIs the transmission line voltage.
The calculation formula of the fully compensated differential current is as follows:
Figure BDA0002679517160000054
in the formula (I), the compound is shown in the specification,
Figure BDA0002679517160000055
it is shown that the differential current is fully compensated,
Figure BDA0002679517160000056
representing the current sampling value of the protection installation at one side of the transmission line,
Figure BDA0002679517160000057
representing the current sampling value of the protection installation at the other side of the transmission line,
Figure BDA0002679517160000058
represents the compensation value of the distributed capacitance current on the transmission line side,
Figure BDA0002679517160000059
uMCwhich represents the voltage on one side of the transmission line,
Figure BDA00026795171600000510
and the secondary instantaneous value of the head end of the shunt reactor at one side of the power transmission line is represented.
Figure BDA00026795171600000511
A compensation value representing the distributed capacitance current on the other side of the transmission line,
Figure BDA00026795171600000512
uNCrepresenting the voltage on the other side of the transmission line,
Figure BDA00026795171600000513
and the secondary instantaneous value of the head end of the shunt reactor at the other side of the transmission line is represented.
Figure BDA00026795171600000514
Indicating A, B or phase C.
The first action equation is:
Figure BDA00026795171600000515
in the formula ITHRepresents the action threshold of the fully compensated differential current protection, k is the rate brake coefficient, takes 0.6,
Figure BDA00026795171600000516
indicating a fully compensated braking current. The fully compensated current differential protection action needs the action equation to be satisfied for the continuous time T1, and the time T1 takes 5 ms.
The formula for calculating the uncompensated differential current is as follows:
Figure BDA0002679517160000061
in the formula (I), the compound is shown in the specification,
Figure BDA0002679517160000062
representing the current sampling value of the protection installation at one side of the transmission line,
Figure BDA0002679517160000063
representing the current sampling value of the protection installation at the other side of the transmission line,
Figure BDA0002679517160000064
representing an uncompensated differential current.
The second action equation is:
Figure BDA0002679517160000065
in the formula ITH' denotes the action threshold value of the uncompensated differential current protection, k is the rate brake coefficient, takes 0.6,
Figure BDA0002679517160000066
representing an uncompensated differential current. Uncompensated current differential protection action requires the equation to be connectedThe time T2 is continued, and T2 is 90 ms. The value of 90ms is that the protection priority action of the shunt reactor is considered according to 30ms of action time when the internal fault of the shunt reactor is considered, and the action time of the breaker mechanism is considered according to 60 ms. When the shunt reactor can not act, the fault of the shunt reactor can be cut off by the shunt reactor fault clearing device.
In a specific implementation manner of the embodiment of the present invention, the method further includes determining a fault location based on the operating states of the fully compensated current differential protection and the uncompensated current differential protection, specifically:
and when the uncompensated current differential protection and the fully compensated current differential protection both act, judging that the fault is positioned in the power transmission line.
And when the uncompensated current differential protection does not act and the fully compensated current differential protection does not act, judging that the fault is positioned in the power transmission line.
And when the uncompensated current differential protection and the fully compensated current differential protection do not act, judging that the fault is positioned outside the power transmission line.
As shown in fig. 2 and 3, the complete compensation method provided by the present invention has a good compensation effect in the transient process of the dynamic change of the current of the parallel reactor and the occurrence of the external fault in the power transmission system, that is, the differential current after complete compensation is significantly smaller than the traditional compensation method based on the capacity of the fixed reactor.
As shown in fig. 4, the uncompensated differential current and the fully compensated differential current during the fault have a significantly increased characteristic, and both the uncompensated current differential protection and the fully compensated current differential protection satisfy the operating condition, and it can be determined that the power transmission line has an internal fault.
When an external fault of the power transmission line occurs, the uncompensated differential current and the fully compensated differential current are as shown in fig. 5, and the uncompensated differential current and the fully compensated differential current are not obvious in degree of amplification and do not meet the preset action threshold. Therefore, the non-compensated current differential protection and the fully compensated current differential protection do not act, and the external fault of the power transmission line can be judged.
When a fault occurs in the shunt reactor, the uncompensated differential current and the fully compensated differential current are as shown in fig. 6, and the increase in the uncompensated differential current will significantly satisfy the operation threshold, while the increase in the fully compensated differential current will not satisfy the operation threshold. Therefore, it can be determined that the shunt reactor has an internal fault without the compensation current differential protection being activated and the complete compensation current differential protection being deactivated.
Fig. 7 shows the ranges of the power transmission line internal fault, the shunt reactor internal fault and the power transmission line external fault mentioned in the invention. The external faults of the power transmission line refer to the range included by internal faults of the non-power transmission line and internal faults of the shunt reactor.
The protection sampling in the invention is realized by an alternating current mutual inductor, and the current differential protection method of the power transmission line further comprises the following steps: when the AC transformer is judged to be abnormal, the complete compensation current differential protection is controlled to instantly quit the differential calculation and logic execution, and the differential calculation and logic execution is controlled without the compensation current differential protection. The abnormality comprises the disconnection of a secondary circuit of a voltage transformer and a shunt reactor current transformer of the power transmission line or the saturation of the shunt reactor current transformer. In the invention, the technology known in the field is adopted when the abnormity of the alternating current transformer is judged.
The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (11)

1. A current differential protection method suitable for a power transmission line connected with a shunt reactor is characterized by comprising the following steps:
acquiring time domain capacitance current of the power transmission line and secondary instantaneous current of a shunt reactor connected with the power transmission line;
after the time domain capacitance current and the secondary instantaneous current of the shunt reactor are superposed, a compensation value of the distributed capacitance current of the power transmission line is obtained;
substituting the compensation value of the distributed capacitance current and the sampling values of the protection installation positions at two sides of the power transmission line into a complete compensation differential current calculation formula, calculating a complete compensation differential current, and calculating a complete compensation differential current;
substituting sampling values at the protective installation positions at two sides of the power transmission line into an uncompensated differential current calculation formula to calculate uncompensated differential current;
judging whether to start the fully compensated current differential protection or not based on the fully compensated differential current and a preset first action equation;
and judging whether to start the uncompensated current differential protection or not based on the uncompensated differential current and a preset second action equation.
2. The current differential protection method suitable for the power transmission line accessed by the multi-type shunt reactors according to claim 1, wherein the calculation formula of the compensation value of the distributed capacitance current is as follows:
Figure FDA0002679517150000011
in the formula (I), the compound is shown in the specification,
Figure FDA0002679517150000012
for the compensation value of the distributed capacitance current,
Figure FDA0002679517150000013
is the secondary instantaneous current of A phase or B phase or C phase at the head end of the shunt reactor,
Figure FDA0002679517150000014
is the time domain capacitance current of the transmission line and the C transmission line parameterNumber of equivalent capacitance values ucIs the transmission line voltage.
3. The current differential protection method suitable for the power transmission line accessed by the multi-type shunt reactors according to claim 1, wherein the calculation formula of the full compensation differential current is as follows:
Figure FDA0002679517150000015
in the formula (I), the compound is shown in the specification,
Figure FDA0002679517150000016
it is shown that the differential current is fully compensated,
Figure FDA0002679517150000017
representing the current sampling value of the protection installation at one side of the transmission line,
Figure FDA0002679517150000018
representing the current sampling value of the protection installation at the other side of the transmission line,
Figure FDA0002679517150000019
represents the compensation value of the distributed capacitance current on the transmission line side,
Figure FDA00026795171500000110
uMCwhich represents the voltage on one side of the transmission line,
Figure FDA00026795171500000111
represents the secondary instantaneous value of the head end of the shunt reactor on one side of the transmission line,
Figure FDA00026795171500000112
a compensation value representing the distributed capacitance current on the other side of the transmission line,
Figure FDA00026795171500000113
uNCrepresenting the voltage on the other side of the transmission line,
Figure FDA00026795171500000114
represents the secondary instantaneous value of the head end of the shunt reactor at the other side of the transmission line,
Figure FDA0002679517150000021
indicating A, B or phase C.
4. The current differential protection method suitable for the power transmission line accessed by the multi-type shunt reactors according to claim 3, wherein the first action equation is as follows:
Figure FDA0002679517150000022
in the formula ITHRepresenting the action threshold of the fully compensated differential current protection,
Figure FDA0002679517150000023
indicating a fully compensated braking current and k a rate braking coefficient.
5. The current differential protection method suitable for the power transmission line accessed by the multi-type shunt reactors according to claim 1, wherein the calculation formula of the uncompensated differential current is as follows:
Figure FDA0002679517150000024
in the formula (I), the compound is shown in the specification,
Figure FDA0002679517150000025
representing the current sampling value of the protection installation at one side of the transmission line,
Figure FDA0002679517150000026
representing the current sampling value of the protection installation at the other side of the transmission line,
Figure FDA0002679517150000027
representing an uncompensated differential current.
6. The current differential protection method suitable for the power transmission line accessed by the multi-type shunt reactors according to claim 5, wherein the second action equation is as follows:
Figure FDA0002679517150000028
in the formula ITH' represents the action threshold of the uncompensated differential current protection, which is 1.5 times of the action threshold of the fully compensated differential current protection, k is the ratio brake coefficient,
Figure FDA0002679517150000029
indicating an uncompensated braking current.
7. The method for current differential protection of the power transmission line accessed by the multi-type shunt reactors according to claim 1, characterized in that the method further comprises judging the fault position based on the working states of the fully compensated current differential protection and the uncompensated current differential protection.
8. The current differential protection method suitable for the power transmission line accessed by the multi-type shunt reactors according to claim 7, is characterized in that: and when the uncompensated current differential protection and the fully compensated current differential protection both act, judging that the fault is positioned in the power transmission line.
9. The current differential protection method suitable for the power transmission line accessed by the multi-type shunt reactors according to claim 7, is characterized in that: and when the uncompensated current differential protection does not act and the fully compensated current differential protection does not act, judging that the fault is positioned in the shunt reactor.
10. The current differential protection method suitable for the power transmission line accessed by the multi-type shunt reactors according to claim 7, is characterized in that: and when the uncompensated current differential protection and the fully compensated current differential protection do not act, judging that the fault is positioned outside the power transmission line.
11. The current differential protection method suitable for the power transmission line accessed by the multi-type shunt reactors according to claim 1, wherein sampling values of protection installation positions on two sides of the power transmission line are collected by an alternating current transformer, and the method further comprises the following steps:
when the AC transformer is judged to be abnormal, the complete compensation current differential protection is controlled to instantly quit the differential calculation and logic execution, and the differential calculation and logic execution is controlled without the compensation current differential protection.
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CN114400633A (en) * 2022-01-06 2022-04-26 北京四方继保工程技术有限公司 Method for realizing capacitance current compensation by current differential protection of T-connection circuit
CN116345388A (en) * 2023-04-13 2023-06-27 南京国电南自电网自动化有限公司 Method for preventing CT saturation differential protection misoperation during air drop of shunt reactor

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CN116345388A (en) * 2023-04-13 2023-06-27 南京国电南自电网自动化有限公司 Method for preventing CT saturation differential protection misoperation during air drop of shunt reactor

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