CN108879590A - The power distribution network accelerated based on negative sequence impedance unifies inverse time lag zero-sequence over-current protection method - Google Patents

The power distribution network accelerated based on negative sequence impedance unifies inverse time lag zero-sequence over-current protection method Download PDF

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Publication number
CN108879590A
CN108879590A CN201810674863.5A CN201810674863A CN108879590A CN 108879590 A CN108879590 A CN 108879590A CN 201810674863 A CN201810674863 A CN 201810674863A CN 108879590 A CN108879590 A CN 108879590A
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sequence
current
zero
negative
switch
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CN108879590B (en
Inventor
王林波
杨凤生
王元峰
陈琪
王冕
曾惜
王恩伟
王宏远
杨金铎
罗勋华
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Guizhou Power Grid Co Ltd
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Guizhou Power Grid Co Ltd
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    • 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
    • H02H3/08—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 excess current
    • 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
    • H02H3/02—Details
    • 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
    • H02H3/40—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 ratio of voltage and current

Abstract

The invention discloses a kind of power distribution networks accelerated based on negative sequence impedance to unify inverse time lag zero-sequence over-current protection method, it includes：Step 1, when singlephase earth fault occurs for distribution line, after the block switch on faulty line on failure path perceives the zero-sequence current higher than initiation value, path failure information is uploaded to substation's outlet switch by communication channel；Step 2, substation's outlet switch count breakdown switch quantity N, and quantity N are fed back to the block switch for flowing through failure zero-sequence current；Step 3, the actuation time for calculating the block switch according to N value and zero-sequence current value according to block switch；When the prior art is directed to the distribution system single phase earthing failure of non-effective earthing; current inverse time current protection usually requires to adjust step by step since line end to source side; every grade of inverse time lag constant is protected by next stage and is limited; it is differential that the time is pulled open using different time constants in each protection installation place, thus adjusts very cumbersome etc. technical problems.

Description

The power distribution network accelerated based on negative sequence impedance unifies inverse time lag zero-sequence over-current protection method
Technical field
The invention belongs to distribution line failure diagnostic techniques more particularly to a kind of power distribution network systems accelerated based on negative sequence impedance One inverse time lag zero-sequence over-current protection method.
Background technique
For the distribution system of neutral non-effective grounding, fault current is unconspicuous when in order to solve singlephase earth fault Neutral point is concatenated small resistance after detecting residual voltage by problem, part distribution network, forms small resistance grounding system, to increase Major break down electric current is convenient for protection act.At this point, there are certain difficulties for traditional three-stage zero-sequence over-current protection application：(1) city Distribution line generallys use equal loads or equidistant segmentation, and every section of distribution line is only 3~5 kilometers long, and short-term road makes zero sequence The adjusting of current quick and the cooperation for definiting time-lag zero-sequence current protection are more difficult；(2) zero-sequence over-current protection is definited time-lag Setting time fix, and most of protected elements allow through time of fault current and fault current inversely； (3) for short dot closer to power supply, fault current is bigger, and overcurrent protection actuation time is longer.And inverse time lag zero-sequence current protection Has the function of three-stage zero-sequence current protection to a certain extent, and even if the case where grid operation mode changes greatly Under, operating time of protections at different levels can also cooperate automatically, the selectivity of safety action.But current inverse time current protection usually needs It to be adjusted step by step since line end to source side, every grade of inverse time lag constant is protected by next stage to be limited, each protection It is differential that the time is pulled open using different time constants in installation place, thus adjusts very cumbersome.
Summary of the invention
The technical problem to be solved by the present invention is to：There is provided it is a kind of based on negative sequence impedance accelerate power distribution network unify the inverse time lag zero Sequence over-current protection method, when being directed to the distribution system single phase earthing failure of non-effective earthing to solve the prior art, current is anti- Time limit current protection usually requires to adjust step by step since line end to source side, and every grade of inverse time lag constant is by next stage Protection limitation, it is differential that the time is pulled open using different time constants in each protection installation place, thus adjusts very cumbersome etc. skills Art problem.
The technical scheme is that：
It is a kind of based on negative sequence impedance accelerate power distribution network unify inverse time lag zero-sequence over-current protection method, it includes：
Step 1, the block switch when singlephase earth fault occurs for distribution line, on faulty line on failure path After perceiving the zero-sequence current higher than initiation value, path failure information is uploaded to substation's outlet switch by communication channel；
Step 2, substation's outlet switch count breakdown switch quantity N, and quantity N are fed back to and flows through failure zero-sequence current Block switch；
Step 3, the actuation time for calculating the block switch according to N value and zero-sequence current value according to block switch.
Calculate the public affairs of the actuation time of the block switch described in step 3 according to N value and zero-sequence current value according to block switch Formula is：
In formula：T is actuation time；K is time constant；I is fault current；Iop is starting current, and α is inverse-time curve Form factor；β is curvilinear translation coefficient；N is the failure block switch quantity of outlet switch statistics, Zm2For block switch measurement point Negative sequence impedance；Zs2The negative sequence impedance reflected by every kilometer of route, l are the line length of equidistant segmentation.
The negative sequence impedance Zs2Calculation method be according to the negative sequence voltage and negative-sequence current of measurement point calculate；
The calculation formula of negative sequence voltage is：
Negative-sequence current calculation formula is：
Beneficial effect of the present invention：
The invention proposes the method for obtaining negative-sequence current, negative sequence voltage under existing measuring condition, what is proposed is negative Sequence impedance is not influenced by fault resstance, can guarantee that the time between the superior and the subordinate's protection is differential by communication channel Cooperation；It does not need to be adjusted again, when solving the distribution system single phase earthing failure that the prior art is directed to non-effective earthing, mesh Preceding inverse time current protection usually requires to adjust step by step since line end to source side, every grade of inverse time lag constant by Next stage protection limitation, it is differential that the time is pulled open using different time constants in each protection installation place, thus adjusts very numerous The technical problems such as trivial.
Specific embodiment
It is a kind of based on negative sequence impedance accelerate power distribution network unify inverse time lag zero-sequence over-current protection method, it includes：
Step 1, the block switch when singlephase earth fault occurs for distribution line, on faulty line on failure path After perceiving the zero-sequence current higher than initiation value, path failure information is uploaded to substation's outlet switch by communication channel；
Step 2, substation's outlet switch count breakdown switch quantity N, and quantity N are fed back to and flows through failure zero-sequence current Block switch；
Step 3, the actuation time for calculating the block switch according to N value and zero-sequence current value according to block switch.
Calculate the public affairs of the actuation time of the block switch described in step 3 according to N value and zero-sequence current value according to block switch Formula is：
In formula：T is actuation time；K is time constant；I is fault current；Iop is starting current, and α is inverse-time curve Form factor；β is curvilinear translation coefficient, and general value is 1；N is the failure block switch quantity of outlet switch statistics, Zm2To divide Duan Kaiguan measurement point negative sequence impedance；Zs2The negative sequence impedance reflected by every kilometer of route, l are the line length of equidistant segmentation.
The present invention is directed to the radial distribution system of equidistant segmentation, and ground fault zero-sequence current flows back to system by fault point Side, the zero-sequence current that block switch is perceived on failure path is almost the same, using unified inverse time lag zero-sequence over-current protection when institute Obtained actuation time is identical, it is only necessary to the nearest block switch protection act of distance fault point；Therefore and present invention introduces add Fast factor pair operating time of protection is modified, to guarantee that it is very poor that the actuation time of the superior and the subordinate's block switch is pulled open.
The differential Δ t of the minimum time that protective switch the superior and the subordinate allow to pull open is when the protection window time adding the movement of breaker Between, the general actuation time of 10kV breaker is 40~70ms, takes Δ t=0.5s after fully considering certain nargin.Due to segmentation Switch measurement point negative sequence impedance can reflect measurement point arrive system side distance, therefore the present invention utilize equidistant segmentation negative phase-sequence Impedance is time differential modifying factor, so as to calculate the actuation time of block switch, accurately to realize protection.
Since current complexes can only obtain two line voltages, biphase current and zero-sequence current mostly.Only wired VoltageWithIn the case where following formula can be used obtain negative sequence voltages
A=e in formulaj120°, in only phase currentAnd zero-sequence currentIn the case where can use following formula obtain negative phase-sequence electricity Stream：
Negative-sequence current calculation formula is：

Claims (3)

1. a kind of power distribution network accelerated based on negative sequence impedance unifies inverse time lag zero-sequence over-current protection method, it includes：
Step 1, the block switch perception when singlephase earth fault occurs for distribution line, on faulty line on failure path To after being higher than the zero-sequence current of initiation value, path failure information is uploaded to substation's outlet switch by communication channel；
Step 2, substation's outlet switch count breakdown switch quantity N, and quantity N is fed back to point for flowing through failure zero-sequence current Duan Kaiguan；
Step 3, the actuation time for calculating the block switch according to N value and zero-sequence current value according to block switch.
2. a kind of power distribution network accelerated based on negative sequence impedance according to claim 1 unifies inverse time lag zero-sequence over-current protection side Method, it is characterised in that：When calculating the movement of the block switch according to N value and zero-sequence current value according to block switch described in step 3 Between formula be：
In formula：T is actuation time；K is time constant；I is fault current；IopFor starting current, α is inverse-time curve shape system Number；β is curvilinear translation coefficient；N is the failure block switch quantity of outlet switch statistics, Zm2For the resistance of block switch measurement point negative phase-sequence It is anti-；Zs2The negative sequence impedance reflected by every kilometer of route, l are the line length of equidistant segmentation.
3. a kind of power distribution network accelerated based on negative sequence impedance according to claim 1 unifies inverse time lag zero-sequence over-current protection side Method, it is characterised in that：The negative sequence impedance Zs2Calculation method be according to the negative sequence voltage and negative-sequence current of measurement point calculate；
The calculation formula of negative sequence voltage is：
Negative-sequence current calculation formula is：
CN201810674863.5A 2018-06-27 2018-06-27 The power distribution network accelerated based on negative sequence impedance unifies inverse time lag zero-sequence over-current protection method Active CN108879590B (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060077605A1 (en) * 2004-10-08 2006-04-13 Folkers Ralph W Compensated inverse-time undervoltage load shedding systems
CN103855619A (en) * 2014-03-31 2014-06-11 国网上海市电力公司 Integrated automation transformer substation
CN105024364A (en) * 2015-07-24 2015-11-04 国家电网公司 Analysis method for influence on distance protection caused by access of large-scale wind power equipment to AC/DC hybrid system
CN106711968A (en) * 2016-12-29 2017-05-24 中国电力科学研究院 Inverse-time-lag zero-sequence current protection setting method and system
CN106816855A (en) * 2015-11-27 2017-06-09 中国电力科学研究院 A kind of inverse time current protection method

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060077605A1 (en) * 2004-10-08 2006-04-13 Folkers Ralph W Compensated inverse-time undervoltage load shedding systems
CN103855619A (en) * 2014-03-31 2014-06-11 国网上海市电力公司 Integrated automation transformer substation
CN105024364A (en) * 2015-07-24 2015-11-04 国家电网公司 Analysis method for influence on distance protection caused by access of large-scale wind power equipment to AC/DC hybrid system
CN106816855A (en) * 2015-11-27 2017-06-09 中国电力科学研究院 A kind of inverse time current protection method
CN106711968A (en) * 2016-12-29 2017-05-24 中国电力科学研究院 Inverse-time-lag zero-sequence current protection setting method and system

Non-Patent Citations (1)

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Title
吴麟琳等: "平行双回线对反时限零序电流保护的影响及改进算法", 《电网技术》 *

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