CN105552861B - Adaptive current protection algorithm - Google Patents

Adaptive current protection algorithm Download PDF

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Publication number
CN105552861B
CN105552861B CN201511017688.5A CN201511017688A CN105552861B CN 105552861 B CN105552861 B CN 105552861B CN 201511017688 A CN201511017688 A CN 201511017688A CN 105552861 B CN105552861 B CN 105552861B
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Prior art keywords
sequence
protection
zero
impedance
current
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CN105552861A (en
Inventor
吴蕾
于广耀
陈萍
徐荥
冯蕾
王瑞平
周春晓
毛吉亮
黄晓博
张晓慧
李鹏达
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PowerChina Henan Electric Power Survey and Design Institute Co Ltd
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Hennan Electric Power Survey and Design Institute
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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
    • 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
    • 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
    • H02H7/267—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 for parallel lines and wires

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  • Emergency Protection Circuit Devices (AREA)

Abstract

The invention discloses a kind of adaptive Current Protection algorithm, comprise the following steps：1）When short trouble occurs, protection act discriminating program starts；2）Protection act discriminating program extracts the protected level voltage sample data and protected level current sampling data of one or half period, calculates three-phase voltage, electric current phasor；3）Calculate negative phase-sequence/residual voltage, electric current phasor in decimation periods；4）Computing system negative phase-sequence, zero sequence impedance；5）According to preset line impedance, system potential, offside system impedance（It is only used for zero-sequence current protection）With adaptive setting formula, the system negative sequence impedance calculated using previous step, zero sequence impedance calculate the real-time setting valve of protection；6）Contrast calculates setting valve and the 3rd in real time）The electric current phasor calculated is walked, judges whether protection should act.As judged to act, trip protection.The present invention is logical to solve the problems, such as current protection using fixed setting valve, realizes protection domain and is relatively fixed, has certain popularization Practical significance.

Description

Adaptive Current Protection algorithm
Technical field
The present invention relates to a kind of relay protection algorithm, and in particular to a kind of line current relay protection algorithm.
Background technology
Conventional current protection calculates this section of line short circuit current using system potential/(system impedance+this section of line impedance), The setting valve of protection is further calculated, therefore its protection seting value is fixed, when system operation mode changes, system Impedance changes therewith, because setting valve can not change as system impedance changes, causes the protection of now current protection Scope changes (requirement of power system actual motion is desirable to its protection domain and is relatively fixed), is the intrinsic of current protection Shortcoming.
The content of the invention
The technical problem to be solved in the present invention is to provide a kind of adaptive Current Protection algorithm, the present invention solves traditional electricity Stream protection seting value can not change as system impedance changes, the skill that protection domain changes therewith when causing the system impedance to change Art problem.
The present invention is achieved through the following technical solutions：
A kind of adaptive Current Protection algorithm, comprises the following steps：
Step 1: when short trouble occurs, protection device fault initiating program starts protection act discriminating program；
Step 2: protection act discriminating program extracts the protected level voltage sample data and protected level of one or half period Current sampling data, three-phase voltage, electric current phasor in decimation periods are calculated using Fourier algorithm；
Step 3: calculate negative sequence voltage, electric current phasor, residual voltage and electric current phase in decimation periods with phase sequence transfer algorithm Amount, obtain protecting the negative sequence voltage U of installation placebh2, residual voltage Ubh0With the negative-sequence current I for flowing through this circuitd2, zero-sequence current Id0；
Step 4: computing system negative sequence impedance Zxt2；
Zxt2=Ubh2/(-Id2)
Step 5: by system negative sequence impedance Zxt2It is assigned to system impedance Zxt；
Zxt=Zxt2
Step 6: according to the circuit unit length impedance Z pre-entered in devicex, line length l, system potential ExtWith Protection seting safety factor K, calculate the line impedance Z from protection installation place to line endxl, line end occur three-phase shortcircuit When short circuit current Idl；
Zxl=Zx*l；
Idl=Ext/(Zxt+Zxl)
Step 7: calculate the real-time setting valve I of protectionbhdz；
Ibhdz=K*Idl=K* (Ext/(Zxt+Zxl))
Step 8: contrast calculates setting valve I in real timebhdzThe electric current phasor calculated with above-mentioned 3rd step, judge protection dress Whether put act；If so, the current quick tripping operation of protection device；If it is not, go to the 9th step；
Step 9: whether inquiry fault initiating program returns, if so, EP (end of program)；If it is not, go to second step.
A kind of Adaptive Zero-sequence Current Protection algorithm, comprises the following steps：
Step 1: when short trouble occurs, protection device fault initiating program starts protection act discriminating program；
Step 2: protection act discriminating program extracts the protected level voltage sample data and protected level of one or half period Current sampling data, three-phase voltage, electric current phasor in decimation periods are calculated using Fourier algorithm；
Step 3: calculate negative sequence voltage, electric current phasor, residual voltage and electric current phase in decimation periods with phase sequence transfer algorithm Amount, obtain protecting the negative sequence voltage U of installation placebh2, residual voltage Ubh0With the negative-sequence current I for flowing through this circuitd2, zero-sequence current Id0；
Step 4: definition protection installation place behind system is M sides, it is N sides to define circuit offside system, calculates M side systems Negative sequence impedance ZxtM2, zero sequence impedance ZxtM0；
ZxtM2=Ubh2/(-Id2)
ZxtM0=Ubh0/(-Id0)
Step 5: according to the circuit unit length impedance Z pre-entered in devicex, circuit unit length zero sequence impedance Zx0、 Line length l, M side system potential ExtM, N side system potentials ExtN, N side system positive sequence impedances ZxtN1, N side system negative sequence impedances ZxtN2With N side system zero sequence impedances ZxtN0, the combined impedance Z of calculating positive sequence, negative phase-sequence and zero-sequence network∑1、Z∑2And Z∑0；
Step 501) calculates M side system positive sequence impedances ZxtM1；
ZxtM1=ZxtM2；
Step 502) calculates this section of circuit positive sequence, negative phase-sequence and zero sequence impedance Zxl1、Zxl2And Zxl0；
Zxl1=Zxl2=Zx*l；Zxl0=Zx0*l；
Step 503) calculates the combined impedance Z of positive sequence, negative phase-sequence and zero-sequence network∑1、Z∑2And Z∑0, wherein // represent simultaneously through transport Calculate；
Z∑1=(ZxtM1+Zxl1)//ZxtN1=(ZxtM1+Zxl1)*ZxtN1/(ZxtM1+Zxl1+ZxtN1)
Z∑2=(ZxtM2+Zxl2)//ZxtN2=(ZxtM2+Zxl2)*ZxtN2/(ZxtM2+Zxl2+ZxtN2)
Z∑0=(ZxtM0+Zxl0)//ZxtN0=(ZxtM0+Zxl0)*ZxtN0/(ZxtM0+Zxl0+ZxtN0)
Step 6: calculate the zero-sequence current I of short dot0：
Step 601) calculates power supply equivalence electromotive force E in positive sequence network∑xt：
E∑xt=(ExtM*ZxtN1+ExtN*ZxtM1)/(ZxtM1+ZxtN1)
Step 602) calculates zero-sequence current I during single-line to ground fault using sequence network method01：
I01=E∑xt/(Z∑1+Z∑2+Z∑0)
The zero-sequence current I for protecting installation place to flow through during single-line to ground fault0M1=I01*ZxtN0/(ZxtM0+Zxl0+ZxtN0)
Step 603) calculates zero-sequence current I during two-phase grounding fault using sequence network method02：
I02=E∑xt/(Z∑1+Z∑2//Z∑0)=E∑xt/(Z∑1+Z∑2*Z∑0/(Z∑2+Z∑0))=Z∑2*E∑xt/(Z∑1*Z∑2+ Z∑2*Z∑0+Z∑0*Z∑1)
The zero-sequence current I for protecting installation place to flow through during two-phase grounding fault0M2=I02*ZxtN0/(ZxtM0+Zxl0+ZxtN0)
Step 7: according to preset protection seting safety factor K, zero-sequence current route protection I section adaptive setting values are calculated
Ibhdz0：
I0max=max (I0M1, I0M2)
Ibhdz0=K*3I0max
Step 8: contrast real-time adaptive setting value Ibhdz0The electric current phasor calculated with above-mentioned 3rd step, judge that protection is It is no to act；If so, the current quick tripping operation of protection device；If it is not, go to the 9th step；
Step 9: whether inquiry fault initiating program returns, if so, EP (end of program)；If it is not, go to second step.
When circuit offside non-transformer, when circuit offside is load and the star transformer without neutral-point solid ground, ZxtN1、ZxtN2For the positive and negative sequence impedance of load, protection device, Z are pre-entered after measurementxtN0Pre-enter as infinity.
When circuit offside non-transformer, circuit offside is load and has the star transformation of the neutral-point solid ground of quantity fixation During device, ZxtN1、ZxtN2For the positive and negative sequence impedance of load, protection device, Z are pre-entered after measurementxtN0With the star of neutral ground Shape transformer impedance, quantity and connection type are relevant, and protection device is pre-entered after measurement.
When circuit offside has power supply, circuit is unchanged to the negative sequence impedance of side system and has the neutral point of quantity fixation direct During the star transformer of ground connection, ZxtN1、ZxtN2For the positive and negative sequence impedance of load, protection device, Z are pre-entered after measurementxtN0With The star transformer impedance of neutral ground, quantity and connection type are relevant, and protection device is pre-entered after measurement.
K span is [1.2,1.3].
The present invention protects negative sequence voltage, negative-sequence current, residual voltage, the zero sequence electricity of installation place when occurring by measuring failure Stream calculation system negative sequence impedance and system zero sequence impedance, as system impedance, and this section of circuit pre-entered in join protection Impedance value calculate the setting valve of this section of circuit, solve the problems, such as current protection using fixed setting valve, realize protection model Enclose and be relatively fixed.What the protection domain that the present invention can solve current protection as a rule changed and changed with system impedance Problem, there is certain popularization Practical significance.
Brief description of the drawings
Fig. 1 is that in circuit k points earth fault figure occurs for single supply system；
Fig. 2 is positive sequence network figure of the single supply system when circuit k points break down；
Fig. 3 is negative sequence network figure of the single supply system when circuit k points break down；
Fig. 4 is negative sequence voltage distribution map of the single supply system when circuit k points break down；
Fig. 5 is zero-sequence network figure of the single supply system when circuit k points break down；
Fig. 6 is residual voltage distribution map of the single supply system when circuit k points break down.
Fig. 7 is that in N side bus (being equivalent at subordinate's line outlet) earth fault figure occurs for bilateral source system；
Fig. 8 is bilateral source system positive sequence net when earth fault occurs for N side bus (being equivalent at subordinate's line outlet) Network figure；
Fig. 9 is that negative sequence network during earth fault occurs for bilateral source system N side bus (being equivalent at subordinate's line outlet) Figure；
Figure 10 is that zero-sequence network during earth fault occurs for bilateral source system N side bus (being equivalent at subordinate's line outlet) Figure；
Figure 11 is the base program flow chart of adaptive guard algorithm of the present invention.
Embodiment
The common short trouble of power system mainly has single-phase earthing, line to line fault, two phase ground, three-phase shortcircuit etc..
When there is asymmetry short circuit, negative sequence voltage and negative-sequence current can be produced in protection installation place；It is being grounded When short-circuit, residual voltage and zero-sequence current can be produced in protection installation place.Analyzed according to sequence network method, in short circuit, seen merely Negative sequence network, its power supply is in short dot, like this, can be with rather than system side of the positive sequence network power supply in protection installation place The negative sequence voltage and negative-sequence current got according to protection installation place measurement, computing system side negative sequence impedance similarly, can be according to guarantor The residual voltage and zero-sequence current that shield installation place measurement is got, computing system side zero sequence impedance.
As a rule, the positive sequence impedance of each element is identical with negative sequence impedance in power system, and except generator, because This, in generator electrical distance power network farther out, it is believed that the positive sequence impedance of system is equal with negative sequence impedance.
Therefore, the negative sequence voltage of measurement protection installation place, negative-sequence current, residual voltage, zero sequence when can be occurred with failure The system negative sequence impedance that Current calculation is drawn and system zero sequence impedance, as system impedance, and pre-entered in join protection The impedance value of this section of circuit calculates the setting valve of this section of circuit, so, just solves current protection asking using fixed setting valve Topic, realizes protection domain and is relatively fixed.
(1) common current is protected
Accompanying drawing 1 shows situation of certain single supply system when circuit k points break down, and voltage is mounted with its median generatrix Transformer.According to sequence network analytic approach, the system failure can be divided into positive and negative, three network synthesis analyses of zero sequence.Accompanying drawing 2 is aobvious Positive sequence network figure of certain single supply system when circuit k points break down, wherein E are shownxtFor system potential, Zxt1For system Positive sequence impedance, Ubh1To protect the positive sequence voltage of installation place, Id1To flow through the forward-order current of this circuit, Zxl1For from bus to failure The positive sequence impedance of this section of circuit of point, Uk1For the positive sequence voltage of trouble point.Wherein Ubh1And Id1It can calculate and obtain for protection device The data obtained, three-phase voltage, the electric current that protection device can be arrived by bus-bar potential transformer and line current transformer measurement Change to calculate by phase sequence and obtain, remaining parameter protection device can not directly obtain.
Accompanying drawing 3 shows negative sequence network figure of this system when circuit k points break down, wherein Zxt2For the negative phase-sequence of system Impedance, Ubh2To protect the negative sequence voltage of installation place, Id2To flow through the negative-sequence current of this circuit, Zxl2For from bus to trouble point this The negative sequence impedance of one section of circuit, Uk2For the negative sequence voltage of trouble point.Wherein Ubh2And Id2Acquisition can be calculated for protection device Data, protection device can by bus-bar potential transformer and line current transformer measurement to three-phase voltage, electric current passes through Phase sequence conversion, which calculates, to be obtained, and remaining parameter protection device can not directly obtain.Accompanying drawing 4 shows that this system line k points occur The distribution map of negative sequence voltage during failure, it is assumed that each section of circuit and element X/R coefficients are consistent, and the negative sequence voltage of each point is completely and system Impedance to this point is proportional.
Accompanying drawing 5 shows zero-sequence network figure of this system when circuit k points break down, wherein Zxt0For the zero sequence of system Impedance, Ubh0To protect the residual voltage of installation place, Id0To flow through the zero-sequence current of this circuit, Zxl0For from bus to trouble point this The zero sequence impedance of one section of circuit, Uk0For the residual voltage of trouble point.Wherein Ubh0And Id0The number that can be acquired for protection device According to, protect can be arrived by bus-bar potential transformer and line current transformer measurement three-phase voltage, electric current pass through phase sequence turn Change calculating to obtain, remaining parameter protection device can not directly obtain.
Accompanying drawing 6 shows the distribution map of residual voltage when this system line k points break down, it is assumed that each section of circuit and element X/R coefficients are consistent, and the residual voltage of each point is completely proportional to the impedance of system to this point.
As a rule, the positive sequence impedance of each element is identical with negative sequence impedance in power system, and except generator, because This, in generator electrical distance power network farther out, it is believed that the positive sequence impedance of system is equal with negative sequence impedance.
A kind of adaptive Current Protection algorithm, comprises the following steps：
Step 1: when short trouble occurs, protection device fault initiating program starts protection act discriminating program；
Step 2: protection act discriminating program extracts the protected level voltage sample data and protected level of one or half period Current sampling data, three-phase voltage, electric current phasor in decimation periods are calculated using Fourier algorithm；
Step 3: calculate negative sequence voltage, electric current phasor, residual voltage and electric current phase in decimation periods with phase sequence transfer algorithm Amount, obtain protecting the negative sequence voltage U of installation placebh2, residual voltage Ubh0With the negative-sequence current I for flowing through this circuitd2, zero-sequence current Id0；
Step 4: protection device passes through equation below computing system negative sequence impedance Zxt2；
Zxt2=Ubh2/(-Id2)
Step 5: by system negative sequence impedance Zxt2It is assigned to system impedance Zxt；
Zxt=Zxt2
Step 6: according to the circuit unit length impedance Z pre-entered in devicex, line length l, system potential ExtWith Protection seting safety factor K, calculate the line impedance Z from protection installation place to line endxl, line end occur three-phase shortcircuit When short circuit current Idl；
Zxl=Zx*l；
Idl=Ext/(Zxt+Zxl)
Step 7: calculate the real-time setting valve I of protectionbhdz；
Ibhdz=K*Idl=K* (Ext/(Zxt+Zxl))
Step 8: contrast calculates setting valve I in real timebhdzThe electric current phasor calculated with above-mentioned 3rd step, judge protection dress Whether put act；If so, the current quick tripping operation of protection device；If it is not, go to the 9th step；
Step 9: whether inquiry fault initiating program returns, if so, EP (end of program)；If it is not, go to second step.
Therefore, can inside protection device preset above-mentioned adaptive Current Protection algorithm, by line impedance ZxlAnd system electricity Gesture ExtParameter is stored in advance in line protective devices, is calculated now in the time that protection device can be extremely short after short circuit occurs System negative sequence impedanceZxt2It is equivalent to system impedance Zxt, setting valve is calculated according to system impedance now in real time, by comparing this Setting valve and the electric current of protection device is flowed through judge whether protection device should act.
It is equal with positive sequence impedance or differ less network system, common application that this algorithm is applied to system negative sequence impedance Scope includes：
1) 6, the 10, current protection of 35kV circuits；
2) the 110, current protection of 66kV system end circuits；
3) it is some to subscriber station, the current protection of the end 220kV circuits at ferroelectric station.
(2) zero-sequence current protection
The zero-sequence current protection algorithm of the present invention has limitation, and it can not calculate the system impedance of N sides automatically.Assuming that N Side system is power-supply system (M-N is double power-supply system), and N side system impedances immobilize, should be defeated in advance in protection device Enter the positive and negative zero sequence system impedance in N sides；Assuming that N side systems are the Star Type Transformer that load system has neutral-point solid ground, and N sides System impedance is immobilized, and the positive and negative zero sequence system impedance in N sides should be pre-entered in protection device；Assuming that N side systems are load System and without the Star Type Transformer of neutral-point solid ground, then do not need the impedance data of N sides at all；Assuming that N side systems It can be varied widely for power-supply system (M-N is double power-supply system) and the impedance of N side systems, this algorithm is unable to cope with this feelings Condition.
The setting principle of zero-sequence current protection I sections is single to avoid at subordinate's line outlet (be equivalent to circuit to side bus at) The maximum zero sequence current 3I being likely to occur when phase or two-phase grounding fault0max.As shown in fig. 7, bilateral source system is in N side bus Earth fault occurs for (being equivalent at subordinate's line outlet), and definition protection installation place behind system is M sides, defines circuit offside system Unite as N sides, voltage transformer is mounted with its median generatrix.According to sequence network analytic approach, the system failure can be divided into it is positive and negative, Three network synthesis analyses of zero sequence.Fig. 8, Fig. 9 and Figure 10 are respectively positive sequence, negative phase-sequence and the zero-sequence network figure in the case of this.
The zero-sequence current protection algorithm of the present invention comprises the following steps：
Step 1: when short trouble occurs, protection device fault initiating program starts protection act discriminating program；
Step 2: protection act discriminating program extracts the protected level voltage sample data and protected level of one or half period Current sampling data, three-phase voltage, electric current phasor in decimation periods are calculated using Fourier algorithm；
Step 3: calculate negative sequence voltage, electric current phasor, residual voltage and electric current phase in decimation periods with phase sequence transfer algorithm Amount, obtain protecting the negative sequence voltage U of installation placebh2, residual voltage Ubh0With the negative-sequence current I for flowing through this circuitd2, zero-sequence current Id0；
Step 4: definition protection installation place behind system is M sides, it is N sides to define circuit offside system, calculates M side systems Negative sequence impedance ZxtM2, zero sequence impedance ZxtM0；
ZxtM2=Ubh2/(-Id2)
ZxtM0=Ubh0/(-Id0)
Step 5: according to the circuit unit length impedance Z pre-entered in devicex, circuit unit length zero sequence impedance Zx0、 Line length l, M side system potential ExtM, N side system potentials ExtN, N side system positive sequence impedances ZxtN1, N side system negative sequence impedances ZxtN2With N side system zero sequence impedances ZxtN0, the combined impedance Z of calculating positive sequence, negative phase-sequence and zero-sequence network∑1、Z∑2And Z∑0；
Step 501) calculates M side system positive sequence impedances ZxtM1：
ZxtM1=ZxtM2；
Step 502) calculates this section of circuit positive sequence, negative phase-sequence and zero sequence impedance Zxl1、Zxl2And Zxl0；
Zxl1=Zxl2=Zx*l；Zxl0=Zx0*l；(positive sequence impedance of circuit is typically identical with negative sequence impedance, can unify to count Calculate, the zero sequence impedance of circuit is different from positive sequence impedance, need to individually calculate)
Step 503) calculates the combined impedance Z of positive sequence, negative phase-sequence and zero-sequence network∑1、Z∑2And Z∑0, wherein // represent simultaneously through transport Calculate；
Z∑1=(ZxtM1+Zxl1)//ZxtN1=(ZxtM1+Zxl1)*ZxtN1/(ZxtM1+Zxl1+ZxtN1)
Z∑2=(ZxtM2+Zxl2)//ZxtN2=(ZxtM2+Zxl2)*ZxtN2/(ZxtM2+Zxl2+ZxtN2)
Z∑0=(ZxtM0+Zxl0)//ZxtN0=(ZxtM0+Zxl0)*ZxtN0/(ZxtM0+Zxl0+ZxtN0)
Step 6: calculate the zero-sequence current I of short dot0：
Step 601) calculates power supply equivalence electromotive force E in positive sequence network∑xt：
E∑xt=(ExtM*ZxtN1+ExtN*ZxtM1)/(ZxtM1+ZxtN1)
Step 602) calculates zero-sequence current I during single-line to ground fault using sequence network method01：
I01=E∑xt/(Z∑1+Z∑2+Z∑0)
The zero-sequence current I for protecting installation place to flow through during single-line to ground fault0M1=I01*ZxtN0/(ZxtM0+Zxl0+ZxtN0)
Step 603) calculates zero-sequence current I during two-phase grounding fault using sequence network method02：
I02=E∑xt/(Z∑1+Z∑2//Z∑0)=E∑xt/(Z∑1+Z∑2*Z∑0/(Z∑2+Z∑0))=Z∑2*E∑xt/(Z∑1*Z∑2+ Z∑2*Z∑0+Z∑0*Z∑1)
The zero-sequence current I for protecting installation place to flow through during two-phase grounding fault0M2=I02*ZxtN0/(ZxtM0+Zxl0+ZxtN0)
Step 7: according to preset protection seting safety factor K, zero-sequence current route protection I section adaptive setting values are calculated
Ibhdz0：
I0max=max (I0M1, I0M2)；
Ibhdz0=K*3I0maxWherein K span is [1.2,1.3]；
Step 8: contrast real-time adaptive setting value Ibhdz0The electric current phasor calculated with above-mentioned 3rd step, judge that protection is It is no to act；If so, the current quick tripping operation of protection device；If it is not, go to the 9th step；
Step 9: whether inquiry fault initiating program returns, if so, EP (end of program)；If it is not, go to second step.
When circuit offside non-transformer, when circuit offside is load and the star transformer without neutral-point solid ground, ZxtN1、ZxtN2For the positive and negative sequence impedance of load, protection device, Z are pre-entered after measurementxtN0Pre-enter as infinity.
When circuit offside non-transformer, circuit offside is load and has the star transformation of the neutral-point solid ground of quantity fixation During device, ZxtN1、ZxtN2For the positive and negative sequence impedance of load, protection device, Z are pre-entered after measurementxtN0With the star of neutral ground Shape transformer impedance, quantity and connection type are relevant, and protection device is pre-entered after measurement.
When circuit offside has power supply, circuit is unchanged to the negative sequence impedance of side system and has the neutral point of quantity fixation direct During the star transformer of ground connection, ZxtN1、ZxtN2For the positive and negative sequence impedance of load, protection device, Z are pre-entered after measurementxtN0With The star transformer impedance of neutral ground, quantity and connection type are relevant, and protection device is pre-entered after measurement.
Because M sides protection device can not obtain the electric current and voltage of N sides, so N side system impedances can not be calculated, work as circuit When negative sequence impedance or zero sequence impedance to side system N have large change with the change of system operation mode, this algorithm can not be complete Complete solution determine system impedance change caused by protection domain variation issue.
For single ended power supply network, it is assumed that protection installation place behind system is M sides, and circuit offside load is N sides, equivalent to E in Fig. 1xtNRemove.
Positive and negative sequence is total impedance of the power supply to trouble point：
Z∑1=(ZxtM1+Zxl1)
Z∑2=(ZxtM2+Zxl2)
If load side also has the star transformer of neutral-point solid ground, Z∑0It is calculated as follows：
Z∑0=(ZxtM0+Zxl0)//ZxtN0=(ZxtM0+Zxl0)*ZxtN0/(ZxtM0+Zxl0+ZxtN0)
If load side does not have the star transformer of neutral-point solid ground, Z∑0It is calculated as follows：
Z∑0=(ZxtM0+Zxl0)
When for zero-sequence current route protection, situation is complex, because this algorithm is only capable of calculating the protection installation place back of the body System impedance Z afterwardsxtM2、ZxtM0, and system impedance Z of this section of circuit to side system can not be calculatedxtN2、ZxtN0.Therefore, originally Algorithm is only applicable to following 3 kinds of situations：
1) single-side power, circuit offside is for load and without star transformer (the i.e. offside Z of neutral-point solid groundxtN1、 ZxtN2Protection device, Z are pre-entered after measurementxtN0Pre-enter as infinity, join when this algorithm starts as known data With calculating)；
2) single-side power, circuit offside fix (i.e. offside for load and the star number transformer of neutral-point solid ground ZxtN0It is unchanged, ZxtN1、ZxtN2、ZxtN0Protection device is pre-entered after measurement, is joined when this algorithm starts as known data With calculating)；
3) bilateral source, it is unchanged to side system negative sequence impedance and to the star transformation of neutral-point solid ground in side system Device quantity is fixed (i.e. to side system ZxtN1、ZxtN2、ZxtN0It is unchanged, protection device is pre-entered after measurement, this algorithm opens Participate in calculating as known data when dynamic).
Common application includes：
1) zero-sequence current of 10kV, 20kV circuit for the solidly earthed neutral system that domestic indivedual areas or enterprise use Protection；
2) neutral-point solid ground or wind power plant through low resistance grounding and the 35kV of photovoltaic plant collect the zero sequence of circuit Current protection；
3) zero-sequence current protection of 110kV system ends circuit；
4) zero-sequence current protection that some end 220kV circuits to subscriber station, ferroelectric station are configured.
Accompanying drawing 11 is the base program schematic flow sheet of the adaptive guard algorithm of the present invention.This algorithm can be in most feelings The protection domain for solving the problems, such as current protection under condition changes and changed with system impedance, has certain popularization Practical significance.
Technological means disclosed in the present invention program is not limited only to the technological means disclosed in above-mentioned embodiment, in addition to Formed technical scheme is combined by above technical characteristic.It should be pointed out that for those skilled in the art For, under the premise without departing from the principles of the invention, some improvements and modifications can also be made, these improvements and modifications are also considered as Protection scope of the present invention.

Claims (5)

  1. A kind of 1. Adaptive Zero-sequence Current Protection algorithm, it is characterised in that：Comprise the following steps：
    Step 1: when short trouble occurs, protection device fault initiating program starts protection act discriminating program；
    Step 2: protection act discriminating program extracts the protected level voltage sample data and protected level electric current of one or half period Sampled data, three-phase voltage, electric current phasor in decimation periods are calculated using Fourier algorithm；
    Step 3: negative sequence voltage, electric current phasor, residual voltage and electric current phasor in decimation periods are calculated with phase sequence transfer algorithm, Obtain the negative sequence voltage Ubh2, the residual voltage Ubh0 that protect installation place and the negative-sequence current Id2, the zero-sequence current that flow through this circuit Id0；
    Step 4: definition protection installation place behind system is M sides, it is N sides to define circuit offside system, calculates M side system negative phase-sequences Impedance Z xtM2, zero sequence impedance ZxtM0；
    ZxtM2= Ubh2/(-Id2)
    ZxtM0= Ubh0/(-Id0)
    Step 5: according to the circuit unit length impedance Z x, circuit unit length zero sequence impedance Zx0, line that are pre-entered in device Road length l, M side system potential ExtM, N side system potential ExtN, N side system positive sequence impedance ZxtN1, N side system negative sequence impedance ZxtN2 and N side system zero sequence impedance ZxtN0, calculate combined impedance Z ∑s 1, Z ∑s 2 and the Z ∑s 0 of positive sequence, negative phase-sequence and zero-sequence network；
    Step 501）Calculate M side system positive sequence impedances ZxtM1：
    ZxtM1=ZxtM2；
    Step 502）Calculate this section of circuit positive sequence, negative phase-sequence and zero sequence impedance Zxl1, Zxl2 and Zxl0；
    Zxl1=Zxl2=Zx*l；Zxl0=Zx0*l；
    Step 503）Combined impedance Z ∑s 1, Z ∑s 2 and the Z ∑s 0 of positive sequence, negative phase-sequence and zero-sequence network are calculated, wherein // represent simultaneously through transport Calculate；
    Z∑1=（ZxtM1+Zxl1)//ZxtN1=（ZxtM1+Zxl1)*ZxtN1/（ZxtM1+Zxl1+ZxtN1)
    Z∑2=（ZxtM2+Zxl2)//ZxtN2=（ZxtM2+Zxl2)*ZxtN2/（ZxtM2+Zxl2+ZxtN2)
    Z∑0=（ZxtM0+Zxl0)//ZxtN0=（ZxtM0+Zxl0)*ZxtN0/（ZxtM0+Zxl0+ZxtN0)
    Step 6: calculate the zero-sequence current I0 of short dot：
    Step 601）Calculate power supply equivalence electromotive force E ∑s xt in positive sequence network：
    E∑xt=（ExtM*ZxtN1+ExtN*ZxtM1）/(ZxtM1+ZxtN1)
    Step 602）Zero-sequence current I01 during single-line to ground fault is calculated using sequence network method：
    I01=E∑xt/(Z∑1+Z∑2+Z∑0)
    Zero-sequence current I0M1=the I01*ZxtN0/ for protecting installation place to flow through during single-line to ground fault（ZxtM0+Zxl0+ZxtN0)
    Step 603）Zero-sequence current I02 during two-phase grounding fault is calculated using sequence network method：
    I02=E∑xt/(Z∑1+Z∑2//Z∑0)=E∑xt/（Z∑1+Z∑2*Z∑0/（Z∑2+Z∑0））=Z∑2*E∑ xt/（Z∑1*Z∑2+Z∑2*Z∑0+Z∑0*Z∑1)
    Zero-sequence current I0M2=the I02*ZxtN0/ for protecting installation place to flow through during two-phase grounding fault（ZxtM0+Zxl0+ZxtN0)
    Step 7: according to preset protection seting safety factor K, zero-sequence current route protection I section adaptive setting values are calculated Ibhdz0：
    I0max=max (I0M1, I0M2)
    Ibhdz0=K*3I0max
    Step 8: contrasting the electric current phasor that real-time adaptive setting value Ibhdz0 calculates with above-mentioned 3rd step, protection device is judged Whether should act；If so, the current quick tripping operation of protection device；If it is not, go to the 9th step；
    Step 9: whether inquiry fault initiating program returns, if so, EP (end of program)；If it is not, go to second step.
  2. 2. Adaptive Zero-sequence Current Protection algorithm as claimed in claim 1, it is characterised in that：When circuit offside non-transformer, line When road offside is load and the star transformer without neutral-point solid ground, ZxtN1, ZxtN2 pre-enter guarantor after measurement Protection unit, ZxtN0 are pre-entered as infinity.
  3. 3. Adaptive Zero-sequence Current Protection algorithm as claimed in claim 1, it is characterised in that：When circuit offside non-transformer, line When road offside is load and has the star transformer of the neutral-point solid ground of quantity fixation, ZxtN1, ZxtN2 and ZxtN0 are through surveying Protection device is pre-entered after amount.
  4. 4. Adaptive Zero-sequence Current Protection algorithm as claimed in claim 1, it is characterised in that：When circuit offside has power supply, line Road it is unchanged to the negative sequence impedance of side system and have quantity fix neutral-point solid ground star transformer when, ZxtN1, ZxtN2 and ZxtN0 pre-enter protection device after measurement.
  5. 5. algorithm according to claim 1, it is characterised in that：K span is [1.2,1.3].
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