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CN109387732A - A kind of adaptive in-situ protection method and system of small current grounding fault - Google Patents

A kind of adaptive in-situ protection method and system of small current grounding fault Download PDF

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Publication number
CN109387732A
CN109387732A CN201811573495.1A CN201811573495A CN109387732A CN 109387732 A CN109387732 A CN 109387732A CN 201811573495 A CN201811573495 A CN 201811573495A CN 109387732 A CN109387732 A CN 109387732A
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China
Prior art keywords
real
time zero
reactive power
protection
protection device
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Pending
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CN201811573495.1A
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Chinese (zh)
Inventor
王洪林
赵卫斌
王科
聂鼎
刘红文
徐肖伟
杨金东
李维
范藜涛
董涛
项恩新
宋忧乐
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Electric Power Research Institute of Yunnan Power System Ltd
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Electric Power Research Institute of Yunnan Power System Ltd
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Priority to CN201811573495.1A priority Critical patent/CN109387732A/en
Publication of CN109387732A publication Critical patent/CN109387732A/en
Pending legal-status Critical Current

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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
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • 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
    • G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
    • 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
    • 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
    • H02H3/16—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 fault current to earth, frame or mass
    • H02H3/162—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 fault current to earth, frame or mass for AC systems
    • H02H3/165—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 fault current to earth, frame or mass for AC systems for three-phase systems

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Mathematical Physics (AREA)
  • Theoretical Computer Science (AREA)
  • Power Engineering (AREA)
  • Emergency Protection Circuit Devices (AREA)

Abstract

The invention discloses a kind of adaptive in-situ protection method and system of small current grounding fault; it include: that transient reactive power is calculated according to the real-time residual voltage of acquisition and real-time zero-sequence current; protective device present position is judged according to transient reactive power; if transient reactive power is less than zero; protective device is located at fault point upstream; judge whether starting protection device according to protective device position; if protective device is located at fault point upstream; starting protection device and protective device starts timing; if protective device timing is delayed more than deliberate action, trip command is issued.Guard method provided by the invention; the detection and protection of small current grounding fault are realized using the electrical quantity of test point local; the judgement of abort situation is realized using transient reactive power, is delayed according to network topology and power supply direction set action; the differential cooperation of switch the superior and the subordinate's time can be met; it not only invests small, but also acts fast good reliability.

Description

A kind of adaptive in-situ protection method and system of small current grounding fault
Technical field
The present invention relates to power supply technique field, in particular to the adaptive in-situ protection method of a kind of small current grounding fault and System.
Background technique
In China's small current neutral grounding system, singlephase earth fault is always the principal mode of distribution network failure, is accounted for about 80% or more, although singlephase earth fault does not influence three-phase load power supply, the operation of long-time tape jam point easily causes event Barrier extension increases people and animals' electric shock risk.Small current grounding fault protection is always the hot spot of power supply department research, is ground in recent years Study carefully and achieve certain development, such as there is scholar to propose the guard method of a kind of automatic circuit and residual voltage cooperation, but failure The processing time minute grade, will cause route in short-term blackout the problem of, reduce power supply reliability.Someone utilizes zero sequence The similar determining fault zone of current waveform, by quickly isolating fault zone by line feed terminals, the method, can dependent on communication It is lower by property.In short, current method is dependent on greatly communication and main website, not only investment is big, but also slow motion, poor reliability.
Summary of the invention
This application provides a kind of adaptive in-situ protection method and system of small current grounding fault, to solve the prior art In small current grounding fault guard method be dependent on communication and main website greatly, not only investment is big, but also slow motion, poor reliability Problem.
In order to solve the above-mentioned technical problem first aspect present invention provides a kind of small current grounding fault and adaptively protects on the spot Maintaining method, which comprises
Acquire the real-time residual voltage and real-time zero-sequence current of sampled point；
Transient reactive power is calculated according to the real-time residual voltage and the real-time zero-sequence current；
Protective device present position is judged according to the size of the transient reactive power, if the transient reactive power is small In zero, then the protective device is located at fault point upstream；
Judge whether starting protection device according to the protective device present position；
If the protective device is located at fault point upstream, starts the protective device and the protective device starts to count When；
Judge whether the protective device timing is more than deliberate action delay；
If the protective device timing is delayed more than deliberate action, trip command is issued.
Preferably, described according to the real-time residual voltage and before the real-time zero-sequence current calculates transient reactive power Further include；
Judge in the n continuous sampled points with the presence or absence of n-1 and the real-time residual voltage of the above sampled point Amplitude be greater than starting threshold value；
If there are n-1 and the width of the real-time residual voltage of the above sampled point in the n continuous sampled points Value is greater than starting threshold value, and it is idle to calculate transient state on the spot according to the real-time residual voltage of the sampled point and the real-time zero-sequence current Otherwise power continues the real-time residual voltage and real-time zero-sequence current of the acquisition sampled point.
Preferably, the calculation formula of the starting threshold value are as follows: Uop=KrelU0。
It preferably, further include that calculating is described pre- before the real-time residual voltage and real-time zero-sequence current of the acquisition sampled point If action delay, calculation formula are as follows: tset=t0+(m-1)Δt。
Preferably, the calculation formula of the transient reactive power are as follows:
Corresponding to the embodiment of the present application in a first aspect, according to the second aspect of the embodiment of the present application, low current is provided and is connect The adaptive in-situ protection system of earth fault, comprising:
Acquisition unit, for acquiring the real-time residual voltage and real-time zero-sequence current of sampled point；
First computing unit, for calculating the idle function of transient state according to the real-time residual voltage and the real-time zero-sequence current Rate；
First judging unit, for judging protective device present position according to the size of the transient reactive power, if The transient reactive power is less than zero, then the protective device is located at fault point upstream；
Second judgment unit, for judging whether starting protection device according to the protective device present position；
First execution unit starts the protective device and institute if being located at fault point upstream for the protective device It states protective device and starts timing；
Third judging unit, for judging whether the protective device timing is more than deliberate action delay；
Second execution unit issues trip command if be delayed for the protective device timing more than deliberate action.
Preferably, the protection system further include: the 4th judging unit, for judging in the n continuous sampled points With the presence or absence of n-1 and the amplitude of the real-time residual voltage of sampled point described above is greater than starting threshold value；
Third execution unit, if for there are n-1 sampled points a and described above in the n continuous sampled points The amplitude of real-time residual voltage is greater than starting threshold value, according to the real-time residual voltage of the sampled point and the real-time zero-sequence current Transient reactive power is calculated on the spot, otherwise continues the real-time residual voltage and real-time zero-sequence current of the acquisition sampled point.
Preferably, the protection system further include: the second computing unit is calculated for calculating the deliberate action delay Formula are as follows: tset=t0+(m-1)Δt。
The adaptive in-situ protection method of small current grounding fault that the application first aspect provides includes: acquisition sampling first The real-time residual voltage and real-time zero-sequence current of point；Transient state is calculated according to the real-time residual voltage and the real-time zero-sequence current Reactive power；Protective device present position is judged according to the size of the transient reactive power, if the transient reactive power Less than zero, then the protective device is located at fault point upstream；Judge whether starting protection according to the protective device present position Device；If the protective device is located at fault point upstream, starts the protective device and the protective device starts timing；Sentence Whether the protective device timing of breaking is more than deliberate action delay；If the protective device timing is delayed more than deliberate action, Issue trip command.
The application second aspect provides a kind of adaptive in-situ protection system of small current grounding fault, above-mentioned for executing Guard method, the system comprises: acquisition unit, for acquiring the real-time residual voltage and real-time zero-sequence current of sampled point, the One computing unit, for calculating transient reactive power according to the real-time residual voltage and the real-time zero-sequence current, first sentences Disconnected unit, for judging protective device present position according to the size of the transient reactive power, if the idle function of the transient state Rate is less than zero, then the protective device is located at fault point upstream, and second judgment unit is used for the position according to locating for the protective device It sets and judges whether starting protection device, the first execution unit starts institute if being located at fault point upstream for the protective device It states protective device and the protective device starts timing, third judging unit, for judging whether the protective device timing surpasses Deliberate action delay is crossed, the second execution unit issues tripping if be delayed for the protective device timing more than deliberate action Instruction.
It is compared to the prior art, guard method provided by the invention and system, it is real using the electrical quantity of test point local The detection and protection of existing small current grounding fault realize the judgement of abort situation, according to network topology using transient reactive power Relationship and power supply direction set action delay, can meet the differential cooperation of switch the superior and the subordinate's time, not only invest small, but also act Fast good reliability.
Detailed description of the invention
It in order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, below will be to institute in embodiment Attached drawing to be used is needed to be briefly described, it should be apparent that, the accompanying drawings in the following description is only some implementations of the invention Example, for those of ordinary skill in the art, without creative efforts, can also obtain according to these attached drawings Obtain other attached drawings.
Fig. 1 is the flow diagram of the adaptive in-situ protection method of small current grounding fault provided in an embodiment of the present invention；
Fig. 2 is the block diagram of the adaptive in-situ protection system of small current grounding fault provided in an embodiment of the present invention；
Fig. 3 is Single-ring network aerial construction schematic diagram provided in an embodiment of the present invention.
Specific embodiment
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete Whole description, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.It is based on Embodiment in the present invention, it is obtained by those of ordinary skill in the art without making creative efforts every other Embodiment shall fall within the protection scope of the present invention.
Referring to Fig. 1, being the process of the adaptive in-situ protection method of small current grounding fault provided in an embodiment of the present invention Schematic diagram.The described method includes:
Step S101 acquires the real-time residual voltage and real-time zero-sequence current of sampled point.
Specifically, in phase three-wire three circuit, the phasor of three-phase current and it is equal to zero, i.e. Ia+Ib+Ic=0.If three A current transformer is accessed in three line of phase, at this moment induced current is zero.When electric shock or leak current fault occur in circuit, circuit In there is leakage current to flow through, at this moment zero across the three-phase current phasor of mutual inductor and not etc., phasor and are as follows: Ia+Ib+Ic=I (leakage current, i.e. zero-sequence current).Just there is an induced current in mutual inductor secondary coil in this way, this voltage is added on detection part Electronic amplification circuit, with protection zone device predetermined action current value compared with, if more than action current, then make sensitive relay Movement acts on executive component tripping.Here the mutual inductor connect is known as zero sequence current mutual inductor, the phasor of three-phase current and not Equal to zero, generated electric current is zero-sequence current.Background monitoring in zero-sequence current and residual voltage distribution substation or substation Fault-signal is used as in software generally to handle, value is zero under normal circumstances, if there is failure, zero-sequence current and zero The value of sequence voltage is then not zero.
Step S102 calculates transient reactive power according to the real-time residual voltage and the real-time zero-sequence current.
Specifically, the calculation formula of the transient reactive power are as follows:
Wherein, QmFor the idle function of transient state of m point Rate；u0It (t) is m point transient zero-sequence voltage；For u0(t) Hilbert (Hilbert) transformation；T is transient process data Length.
Before calculating transient reactive power according to the real-time residual voltage and the real-time zero-sequence current, further include；
Judge in the n continuous sampled points with the presence or absence of n-1 and the real-time residual voltage of the above sampled point Amplitude be greater than starting threshold value；
If there are n-1 and the width of the real-time residual voltage of the above sampled point in the n continuous sampled points Value is greater than starting threshold value, and it is idle to calculate transient state on the spot according to the real-time residual voltage of the sampled point and the real-time zero-sequence current Otherwise power continues the real-time residual voltage and real-time zero-sequence current of the acquisition sampled point.By protective device (FTU) zero sequence electricity Pressure sampled value is compared with starting door threshold value, if having the n-1 a in a continuous sampled point of n (n > 3) and above sampled point Amplitude is greater than starting threshold value, protective device starting record fault message, and does the processing of next step；Otherwise do not start, continue to adopt Sample.
The calculation formula of the starting threshold value can be with are as follows: Uop=KrelU0.Wherein, KrelFor safety factor；U0To flow through this The residual voltage virtual value of protective device.
Step S103 judges protective device present position according to the size of the transient reactive power, if the transient state Reactive power is less than zero, then the protective device is located at fault point upstream.
Step S104 judges whether starting protection device according to the protective device present position.
Step S105 starts the protective device and the protection fills if the protective device is located at fault point upstream Set beginning timing.
Step S106 judges whether the protective device timing is more than deliberate action delay.
Step S107 issues trip command if the protective device timing is delayed more than deliberate action.
Wherein, a deliberate action delay is set, it can also be in the real-time residual voltage for acquiring sampled point and real-time zero sequence The deliberate action delay, calculation formula are as follows: t are calculated before electric currentset=t0+(m-1)Δt.Wherein, tsetSwitch protection movement The setting valve of time；t0For final distribution transformer or the operation time limit of switch ground protection；Δ t is the time difference；M is switch Number.
The protection act time limit direction and flows through switching device according to the location of switch and the adjusting of power supply direction, power supply Active power direction is identical；The operation time limit of final distribution transformer grounding protection is set as t0, the movement of other switch protections A time limit time differential Δ t (being selected as 0.5s) bigger than the maximum actuation time limit of downstream adjacent switch.If user's distribution becomes Depressor does not configure ground protection, then treats the conduct final stage protection of demarcation switch ground protection.
Fig. 2 is the block diagram of the adaptive in-situ protection system of small current grounding fault provided in an embodiment of the present invention, the system System includes:
Acquisition unit U1001, for acquiring the real-time residual voltage and real-time zero-sequence current of sampled point；
First computing unit U1002, for calculating transient state according to the real-time residual voltage and the real-time zero-sequence current Reactive power；
First judging unit U1003, for judging protective device present position according to the size of the transient reactive power, If the transient reactive power, less than zero, the protective device is located at fault point upstream；
Second judgment unit U1004, for judging whether starting protection device according to the protective device present position；
First execution unit U1005 starts the protective device if being located at fault point upstream for the protective device And the protective device starts timing；
Third judging unit U1006, for judging whether the protective device timing is more than deliberate action delay；
Second execution unit U1007 issues tripping and refers to if be delayed for the protective device timing more than deliberate action It enables.
The system can also include: the 4th judging unit, whether there is in the n continuous sampled points for judging The amplitude of the real-time residual voltage of n-1 sampled point a and described above is greater than starting threshold value；
Third execution unit, if for there are n-1 sampled points a and described above in the n continuous sampled points The amplitude of real-time residual voltage is greater than starting threshold value, according to the real-time residual voltage of the sampled point and the real-time zero-sequence current Transient reactive power is calculated on the spot, otherwise continues the real-time residual voltage and real-time zero-sequence current of the acquisition sampled point.
Second computing unit, for calculating the deliberate action delay, calculation formula are as follows: tset=t0+(m-1)Δt。
From the above technical scheme, it using the block switch and protective device (FTU) on distribution line, acquires on the spot Residual voltage and zero sequence current signal are mutated energy quick start according to residual voltage, by collected residual voltage and zero sequence The transient signal of electric current seeks transient reactive power, according to add up positive and negative judgement test point and the fault point of transient reactive power Relative position, when determining that fault point is located at test point downstream, start-up study protection algorism.According to network topology and power supply The delay of direction set action, sets power supply power supply direction as positive direction, operating time of protection is sequentially reduced, to ensure that small electricity The selectivity for flowing earth-fault protection, automatic to determine power supply direction when line topological changes, change acts definite value, protects The protection act nearest from fault point is demonstrate,proved, adaptive guard is realized.Small current grounding fault provided by the present application is adaptively The detection and protection of small current grounding fault are realized in ground guard method using the electrical quantity of test point local, utilize the idle function of transient state Rate realizes the judgement of abort situation, according to network topology and power supply direction set action delay, can meet switch the superior and the subordinate Time differential cooperation, not only invests small, but also acts fast good reliability.
Fig. 3 is Single-ring network aerial construction schematic diagram provided in an embodiment of the present invention, is embodiment provided by the present application, tool Body,
(1) protective device (FTU) action delay is set.
In Single-ring network overhead transmission line, under normal power supply state, interconnection switch be it is fixed, operate normally be in separating brake shape State is, it is specified that the power supply direction (active power direction) that each protective device of route (FTU) detects at this time is positive.Interconnection switch is Q3, switch installation direction are directed toward route by power supply and are positive, and the side M powers direction by QS1 → Q1 → Q2, the side N power direction by QS2 → Q5→Q4。
The action delay of each protective device (FTU) is set according to the location of switch and power supply direction:
The side the M → side N: QS1 → QS2 is followed successively by 7s, 6s, 5s, 4s, 3s, 2s, 1s, and Q6 and Q7 are set as 0.5s；
The side the N → side M: QS2 → QS1 is followed successively by 1s, 2s, 3s, 4s, 5s, 6s, 7s, and Q6 and Q7 are set as 0.5s；
(2) when small current grounding fault occurs for K1 point.
QS1, Q1, Q2 are mutated energy quick start according to residual voltage, calculate transient reactive power Q, Q < 0 judges failure Point is located at test point downstream.
(3) QS1, Q1, Q2 protection starting, starts timing.
QS1, Q1, Q2 are respectively 7s, 6s, 5s according to active power direction, tripping delay；
Q2 delay is shorter, and Q2 first trips isolated fault；
Interconnection switch Q3 detects that side has pressure, side without pressure, and starting is closed a floodgate；
After contact is closed a floodgate, Q3 detects that output power direction changes；
Q3, Q4, Q5 are respectively 4s, 5s, 6s according to active power direction, tripping delay；
Q3 delay is shorter, and Q3 first trips isolated fault；
Fault point K1 is isolated for Q2, Q3 tripping.
Those skilled in the art after considering the specification and implementing the invention disclosed here, will readily occur to of the invention its Its embodiment.This application is intended to cover any variations, uses, or adaptations of the invention, these modifications, purposes or Person's adaptive change follows general principle of the invention and including the undocumented common knowledge in the art of the present invention Or conventional techniques.The description and examples are only to be considered as illustrative, and true scope and spirit of the invention are by following Claim is pointed out.
It should be understood that the present invention is not limited to the precise structure already described above and shown in the accompanying drawings, and And various modifications and changes may be made without departing from the scope thereof.The scope of the present invention is limited only by the attached claims.

Claims (8)

1.一种小电流接地故障自适应就地保护方法，其特征在于，所述方法包括：1. A method for self-adaptive on-site protection of small current ground faults, characterized in that the method comprises: 采集采样点的实时零序电压和实时零序电流；Collect real-time zero-sequence voltage and real-time zero-sequence current of sampling points; 根据所述实时零序电压和所述实时零序电流计算暂态无功功率；Calculate transient reactive power according to the real-time zero-sequence voltage and the real-time zero-sequence current; 根据所述暂态无功功率的大小判断保护装置所处位置，如果所述暂态无功功率小于零，则所述保护装置位于故障点上游；Determine the location of the protection device according to the magnitude of the transient reactive power, and if the transient reactive power is less than zero, the protection device is located upstream of the fault point; 根据所述保护装置所处位置判断是否启动保护装置；Judging whether to activate the protection device according to the position of the protection device; 如果所述保护装置位于故障点上游，启动所述保护装置且所述保护装置开始计时；If the protection device is located upstream of the fault point, the protection device is activated and the protection device starts timing; 判断所述保护装置计时是否超过预设动作延时；judging whether the timing of the protection device exceeds a preset action delay; 如果所述保护装置计时超过预设动作延时，发出跳闸指令。If the timing of the protection device exceeds the preset action delay, a trip command is issued. 2.如权利要求1所述的小电流接地故障自适应就地保护方法，其特征在于，所述根据所述实时零序电压和所述实时零序电流计算暂态无功功率之前还包括；2. The method for self-adaptive on-site protection of low-current ground faults according to claim 1, characterized in that before calculating the transient reactive power according to the real-time zero-sequence voltage and the real-time zero-sequence current, the method further comprises: 判断n个连续的所述采样点中是否存在n-1个及以上所述采样点的实时零序电压的幅值大于启动阈值；Judging whether there are n-1 or more sampling points in the n consecutive sampling points whose real-time zero-sequence voltage amplitude is greater than the startup threshold; 如果n个连续的所述采样点中存在n-1个及以上所述采样点的实时零序电压的幅值大于启动阈值，根据所述采样点的实时零序电压和所述实时零序电流就地计算暂态无功功率，否则继续所述采集采样点的实时零序电压和实时零序电流。If the amplitude of the real-time zero-sequence voltage of n-1 or more sampling points in the n consecutive sampling points is greater than the startup threshold, according to the real-time zero-sequence voltage of the sampling point and the real-time zero-sequence current The transient reactive power is calculated on the spot, otherwise, the collection of the real-time zero-sequence voltage and real-time zero-sequence current of the sampling point is continued. 3.如权利要求2所述的小电流接地故障自适应就地保护方法，其特征在于，所述启动阈值的计算公式为：Uop＝KrelU0。3 . The low-current ground fault adaptive local protection method according to claim 2 , wherein the calculation formula of the startup threshold is: U op =K rel U 0 . 4 . 4.如权利要求1所述的小电流接地故障自适应就地保护方法，其特征在于，所述采集采样点的实时零序电压和实时零序电流之前还包括计算所述预设动作延时，计算公式为：tset＝t0+(m-1)Δt。4. The method for self-adaptive on-site protection of low-current grounding faults according to claim 1, characterized in that, before the acquisition of the real-time zero-sequence voltage and real-time zero-sequence current of the sampling point, the method further comprises calculating the preset action delay , the calculation formula is: t set =t 0 +(m-1)Δt. 5.如权利要求1所述的小电流接地故障自适应就地保护方法，其特征在于，所述暂态无功功率的计算公式为： 5. The self-adaptive local protection method for small current ground faults according to claim 1, wherein the calculation formula of the transient reactive power is: 6.一种小电流接地故障自适应就地保护系统，用于执行权利要求1至5任意一项权利要求所述的保护方法，其特征在于，所述系统包括：6. A small-current ground fault adaptive local protection system for implementing the protection method according to any one of claims 1 to 5, wherein the system comprises: 采集单元，用于采集采样点的实时零序电压和实时零序电流；The acquisition unit is used to collect the real-time zero-sequence voltage and real-time zero-sequence current of the sampling point; 第一计算单元，用于根据所述实时零序电压和所述实时零序电流计算暂态无功功率；a first calculation unit, configured to calculate transient reactive power according to the real-time zero-sequence voltage and the real-time zero-sequence current; 第一判断单元，用于根据所述暂态无功功率的大小判断保护装置所处位置，如果所述暂态无功功率小于零，则所述保护装置位于故障点上游；a first judging unit, configured to judge the location of the protection device according to the magnitude of the transient reactive power, and if the transient reactive power is less than zero, the protection device is located upstream of the fault point; 第二判断单元，用于根据所述保护装置所处位置判断是否启动保护装置；a second judging unit, configured to judge whether to activate the protective device according to the position of the protective device; 第一执行单元，用于如果所述保护装置位于故障点上游，启动所述保护装置且所述保护装置开始计时；a first execution unit, configured to activate the protection device and start timing the protection device if the protection device is located upstream of the fault point; 第三判断单元，用于判断所述保护装置计时是否超过预设动作延时；a third judging unit, configured to judge whether the timing of the protection device exceeds a preset action delay; 第二执行单元，用于如果所述保护装置计时超过预设动作延时，发出跳闸指令。The second execution unit is configured to issue a trip command if the timing of the protection device exceeds the preset action delay. 7.如权利要求6所述的小电流接地故障自适应就地保护系统，其特征在于，所述保护系统还包括：第四判断单元，用于判断n个连续的所述采样点中是否存在n-1个及以上所述采样点的实时零序电压的幅值大于启动阈值；7 . The low-current ground fault adaptive local protection system according to claim 6 , wherein the protection system further comprises: a fourth judgment unit for judging whether the n continuous sampling points exist or not. 8 . The amplitude of the real-time zero-sequence voltage of n-1 and above sampling points is greater than the start-up threshold; 第三执行单元，用于如果n个连续的所述采样点中存在n-1个及以上所述采样点的实时零序电压的幅值大于启动阈值，根据所述采样点的实时零序电压和所述实时零序电流就地计算暂态无功功率，否则继续所述采集采样点的实时零序电压和实时零序电流。The third execution unit is configured to, if the amplitudes of the real-time zero-sequence voltages of n-1 or more sampling points in the n consecutive sampling points are greater than the startup threshold, according to the real-time zero-sequence voltages of the sampling points Calculate the transient reactive power on the spot with the real-time zero-sequence current, otherwise continue to collect the real-time zero-sequence voltage and real-time zero-sequence current of the sampling point. 8.如权利要求6所述的小电流接地故障自适应就地保护系统，其特征在于，所述保护系统还包括：第二计算单元，用于计算所述预设动作延时，计算公式为：tset＝t0+(m-1)Δt。8 . The low-current ground fault adaptive local protection system according to claim 6 , wherein the protection system further comprises: a second calculation unit for calculating the preset action delay, and the calculation formula is: 8 . : t set =t 0 +(m-1)Δt.
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