CN106684844B - A kind of power distribution network isolated island recognition methods - Google Patents

A kind of power distribution network isolated island recognition methods Download PDF

Info

Publication number
CN106684844B
CN106684844B CN201710093512.0A CN201710093512A CN106684844B CN 106684844 B CN106684844 B CN 106684844B CN 201710093512 A CN201710093512 A CN 201710093512A CN 106684844 B CN106684844 B CN 106684844B
Authority
CN
China
Prior art keywords
isolated island
point
residual voltage
pcc
power distribution
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201710093512.0A
Other languages
Chinese (zh)
Other versions
CN106684844A (en
Inventor
张林利
李立生
邵志敏
孙勇
张世栋
李建修
王昕�
刘合金
樊迪
李玉敦
李广磊
王青
李文杰
郭新胜
田野
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Shandong Electric Power Co Ltd
Dongying Power Supply Co of State Grid Shandong Electric Power Co Ltd
Original Assignee
State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Shandong Electric Power Co Ltd
Dongying Power Supply Co of State Grid Shandong Electric Power Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by State Grid Corp of China SGCC, Electric Power Research Institute of State Grid Shandong Electric Power Co Ltd, Dongying Power Supply Co of State Grid Shandong Electric Power Co Ltd filed Critical State Grid Corp of China SGCC
Priority to CN201710093512.0A priority Critical patent/CN106684844B/en
Publication of CN106684844A publication Critical patent/CN106684844A/en
Application granted granted Critical
Publication of CN106684844B publication Critical patent/CN106684844B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02HEMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00Emergency 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
    • H02H7/26Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/28Sectionalised 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 meshed systems
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08Locating faults in cables, transmission lines, or networks
    • G01R31/081Locating faults in cables, transmission lines, or networks according to type of conductors
    • G01R31/086Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors

Abstract

The invention discloses a kind of power distribution network isolated island recognition methods, major network is primarily adapted for use in using low resistance grounding mode, distributed generation resource uses the active power distribution network of earth-free mode, carries out isolated island detection by detecting the variation of distributed generation resource grid entry point point, that is, PCC point residual voltage.No matter PCC dotted line voltage magnitude whether within the preset range, the present invention can quickly determine the position of singlephase earth fault according to the variation of PCC point residual voltage and carry out isolated island identification, and isolated island check frequency is smaller.

Description

A kind of power distribution network isolated island recognition methods
Technical field
The present invention relates to power distribution network isolated island detection technique fields, more particularly to a kind of power distribution network isolated island recognition methods.
Background technique
Isolated island refers to that grid-connected system is not when power grid leads to power failure due to electric fault, maloperation etc. It can detect power failure and be detached from power grid, continue to power to power grid, the load of grid-connected system and surrounding is made to constitute one The isolated generating system of a uncontrolled self-energizing.Isolated operation can be divided into plan isolated island and unplanned isolated island.Plan isolated island The positive effect of DG can be effectively played, the loss of power failure bring is reduced, improves power supply reliability;And unplanned isolated island may It causes casualties, serious harm is caused to electrical equipment and user, threatens the safe and stable operation of electric system.Therefore, It can fast and effeciently detect isolated island, the generation of non-island phenomenon is avoided to have very important significance entire grid-connected system.
Currently, the isolated island detection that experts and scholars have been directed to distributed generation system both at home and abroad is furtherd investigate, propose A variety of island detection methods.According to detection position, these methods can be divided into two classes: the long-range detection method and distributed electrical of grid side The local detection method of source.Long-range detection is main to detect isolated island using radio communication, needs to add equipment, economy It is low, complicated for operation.Since input cost is higher, this kind of method is not yet used widely in small-sized DG, it is suitable for greatly Power distributed generation resource it is grid-connected.Local detection is to detect isolated island by the monitoring end DG voltage and current signal, again can be into one Step is divided into two kinds, and one is passive type methods, that is, passes through the directly variation of measurement DG output power or PCC point voltage or frequency Variation is to determine whether occur isolated island;Another kind is proactive, i.e., injects and disturb to power grid, and passes through system caused by disturbance Voltage, frequency and the corresponding change of impedance detect isolated island in system.Passive type method due to its without increase hardware circuit, at Sheet is low, is easily achieved, therefore is widely used.
Common passive type isolated island detection technique mainly has: mistake/under-voltage detection method (OVP/UVP), mistake/under-frequency detection method, Voltage harmonic detection method, voltage-phase abrupt climatic change method etc..Although proactive check frequency is smaller, detection accuracy is higher, But since this method introduces disturbance quantity, causes unnecessary transient response, decline distribution network electric energy quality;Its control algolithm More complex, practical application is difficult;Under different load characteristics, there are great differences for detection effect, even fails when serious.Often Active alone island detection technique mainly has: impedance measurement, reactance insertion, output power method of perturbation etc..
Cross/under-voltage isolated island detection method (OVP/UVP) refers to when PCC point voltage magnitude is not in preset normal working zone Domain (U1, U2) when, make DG stop being incorporated into the power networks immediately by issuing control signal, to reach a kind of quilt of anti-islanding operation purpose Dynamic formula isolated island detection method, U1、U2It is the voltage magnitude minimum that permission can be operated normally by the system for the technical standard order that generates electricity by way of merging two or more grid systems Value and maximum value.Distributed grid-connected electricity generation system according to figure 1, when power grid operates normally, that is, circuit breaker Q F closure, this When because power grid effect of clamping down on, the voltage of PCC point will not be abnormal.When isolated island occurs, circuit breaker Q F is disconnected, if DG is supplied There is Δ P ≠ 0 in the active power of the active power and local load consumption answered, PCC point voltage magnitude will generate when unequal Offset, if this offset is sufficiently large, it will be able to detect the generation of isolated island.This Method And Principle is simple, easy to accomplish, economical Property is best, and on power quality without influence.It need to only be judged using existing detection parameters, be not required to additional any hardware electricity Road.
But when the smaller i.e. system work of PCC point voltage magnitude offset is in the normal voltage range of permission, mistake/owe Press isolated island detection method that will fail.Though this method is easy to accomplish but contains sizable check frequency.
Make a concrete analysis of about check frequency as follows: when DG uses power limitation control mode, DG is in the feelings that are normally incorporated into the power networks Under condition, the active-power P of local load consumptionloadThe ratio between the active-power P provided with distributed power generation unit are as follows:
UPCCIndicate PCC point voltage effective value when DG is normally incorporated into the power networks, U 'PCCIndicate DG PCC in isolated operation Point voltage effective value.
In the case of distributed generation system is normally incorporated into the power networks, power grid can be expressed to the active power that local load provides At:
Δ P=Pload-P
The distributed generation system active power mismatch degree before island effect occurs are as follows:
When DG work is normally allowing voltage range (U1、U2) when, active power that power grid and DG are provided to local load Ratio range is:
The distributed power generation unit island effect detection time standard according to as defined in China, when DG grid-connected system operates normally Voltage magnitude upper lower limit value be U respectively2=110%Un、U1=85%Un, DG can be obtained in power limitation control mode by substituting into formula Under mistake/under-voltage method isolated island check frequency (NDZ) are as follows:
Similarly, when DG uses constant current controlling mode, the range of system active power mismatch degree is before isolated island generates:
That is mistake/under-voltage method isolated island check frequency of the DG under constant current controlling mode are as follows:
In conclusion there is check frequency for traditional passive type isolated island detection technique in the prior art, still Lack effective solution scheme.
Summary of the invention
In order to solve the deficiencies in the prior art, it is an object of the invention to improve the low resistance grounding system containing distributed generation resource The problem of isolated island detects when singlephase earth fault, occurs for system, based on the analysis to traditional passive type island detection method, proposes The variation of major network protection front and back DG grid entry point (PCC point) residual voltage is to determine whether occur isolated island when a kind of generation using failure Detection scheme.The present invention takes into account passive type detection method principle simple, good economy performance, on power quality without influencing the advantages of, It is the supplement of traditional passive type isolated island detection technique.
The present invention provides a kind of power distribution network isolated island recognition methods, are primarily adapted for use in major network and use low resistance grounding mode, Distributed generation resource uses the active power distribution network of earth-free mode, by detecting distributed generation resource grid entry point point, that is, PCC point zero sequence The variation of voltage carries out isolated island detection, comprising:
If PCC point residual voltage is always zero, system normal operation does not break down at this time;
If detecting, PCC point residual voltage amplitude is at a time sported by 0 more than or equal to threshold value Uset3Value, then At this, singlephase earth fault occurs for etching system;
After failure continues for some time, if detecting, PCC point residual voltage continues to exist and is being more than or equal to threshold value Uset1On the basis of sport bigger value again, the amplitude after mutation be more than or equal to threshold value Uset2, then fault point is located at this time In isolated island region, and system major network protection act after the failure occurred, form isolated island;
If detecting, PCC point residual voltage amplitude is more than or equal to U by the larger value beforeset3It sports and is less than threshold value Uset4Value, then fault point is located at outside the isolated island region at this time, and system major network protection act after the failure occurred, excision therefore Barrier, wherein Uset2>Uset1>Uset3>Uset4
Further, the active power distribution network is equipped with circuit breaker Q F in the outlet of every route, and PCC point is equipped with voltage Mutual inductor, for detecting the residual voltage of PCC point.
Further, major network uses low resistance grounding mode in the active power distribution network, and DG uses earth-free mode, F1, F2 Indicate 2 different location fault points, wherein F1Between bus and the PCC point of route 1, F2Positioned at route 2, PCC point and bus Distance be L;The distance of fault point to major network power supply is L1;The distance of fault point to PCC point is L2, R1For main net side neutral point To ground resistance.
Further, when systems are functioning properly, circuit breaker Q F1, QF2 is failure to actuate, and PCC point residual voltage is always Zero.
Further, it when singlephase earth fault occurs for system and fault point is located in isolated island region, is jumped in circuit breaker Q F1 Before opening, PCC point residual voltage amplitude is more than or equal to Uset1;QF1 tripping after a period of time, PCC point residual voltage continue In the presence of and sport on the basis of the original more than or equal to Uset2Numerical value, can determine that form isolated island at this time according to the present invention.
Further, when fault point is located at outside isolated island region, before circuit breaker Q F2 tripping, PCC point residual voltage width Value is more than or equal to Uset3;QF2 tripping after a period of time, PCC point residual voltage are less than Uset4, in the range of close to zero, It can determine that according to the present invention and cut off failure at this time.
Further, in F1Singlephase earth fault occurs for point, before obtaining major network protection act, the small resistance containing rotary-type DG Earthing mode distribution net work earthing fault compound sequence network figure obtains the positive sequence, negative phase-sequence, zero sequence impedance of major network side according to compound sequence network figure And the positive sequence of the side DG, negative phase-sequence, zero sequence impedance, and the current in the fault point under DG grid connection state is calculated accordingly, and obtains PCC accordingly Point residual voltage, when singlephase earth fault occurs, after major network protection act, breaker tripping, at this point, DG is together with surrounding Load is formed together isolated island.
Further, when calculating the current in the fault point under DG grid connection state, it is contemplated that the DG capacity in access power distribution network Smaller, grid-connected transformer and DG direct impedance are generally large, and the zero sequence impedance Z ' of the side DGa(0)For a biggish value, therefore Have:
Wherein, Za(1)、Za(2)、Za(0)The respectively positive sequence, negative phase-sequence of major network side, zero sequence impedance, Z 'a(1)、Z’a(2)、Z’a(0)Point Not Wei the side DG positive sequence, negative phase-sequence, zero sequence impedance.
Further, as system F2When A phase ground fault occurs for point, PCC point residual voltage is still before major network protection act One biggish numerical value, after major network protection act, route 1 restores normal operating condition, does not contain zero sequence in route theoretically Voltage considers that error influences, and PCC point residual voltage is within the scope of one close to zero at this time.
Further, the power distribution network isolated island recognition methods is complementary with existing mistake/under-voltage isolated island detection method content, when being When system occurs singlephase earth fault and PCC dotted line voltage magnitude and exceeds preset normal operation range, no matter failure point In outside in isolated island region or isolated island region, mistake/under-voltage detection method can quickly detect isolated island;
When fault point is located in isolated island region and DG capacity matches well with load capacity in isolated island region, mistake/under-voltage guarantor When protection element tripping, since failure is not yet removed, PCC point residual voltage persistently exists, power distribution network isolated island recognition methods of the present invention Isolated island can be accurately detected in mistake/under-voltage detection method failure.
Compared with prior art, the beneficial effects of the present invention are:
The present invention is compared with the long-range detection method of grid side, and the present invention is without increasing additional hardware circuit or independent Protective relay, it is noiseless to power grid, on power quality without influence;Compared with proactive, the present invention is without introducing disturbance Amount, will not cause unnecessary transient response, control principle is simple, easy to accomplish.
The present invention is complementary with existing mistake/under-voltage isolated island detection method content.When singlephase earth fault and PCC point occur for system When line voltage amplitude exceeds preset normal operation range, no matter fault point is located in isolated island region or isolated island region Outside, mistake/under-voltage detection method can all quickly detect isolated island.But when DG capacity matches good with load capacity in isolated island region, Major network protection front and back PCC point voltage change very little, this variable quantity are not enough to start/under-voltage protection element, and isolated island detects just It can fail;In addition, network voltage normal fluctuation causes to malfunction in order to prevent, mistake/under-voltage protection protection threshold value cannot be set Set too low, caused/there are biggish check frequencies for under-voltage detection method.When fault point is located in isolated island region and in isolated island region DG capacity matches well with load capacity, when mistake/under-voltage protection element tripping, since failure is not yet removed, and PCC point residual voltage Lasting to exist, the present invention can accurately detect isolated island in mistake/under-voltage detection method failure.
In short, no matter PCC dotted line voltage magnitude whether within the preset range, the present invention can be according to PCC point zero sequence The variation of voltage quickly determines the position of singlephase earth fault and carries out isolated island identification, and isolated island check frequency is smaller.The present invention Major network is primarily adapted for use in using low resistance grounding mode, DG uses the active power distribution network of earth-free mode.
Detailed description of the invention
The accompanying drawings constituting a part of this application is used to provide further understanding of the present application, and the application's shows Meaning property embodiment and its explanation are not constituted an undue limitation on the present application for explaining the application.
Fig. 1 is distributed grid-connected electricity generation system schematic diagram;
Fig. 2 is the mode of low resistance grounding containing DG distribution net work earthing fault schematic diagram;
Fig. 3 is containing rotary-type DG low resistance grounding mode distribution net work earthing fault compound sequence network figure;
Fig. 4 is isolated island compound sequence network figure;
Fig. 5 is Rf=5 Ω F1Locate failure PCC point residual voltage change curve;
Fig. 6 is Rf=5 Ω F1Locate failure 2.15-2.4s PCC point residual voltage change curve;
Fig. 7 is Rf=5 Ω F1Locate failure 7.15-7.4s PCC point residual voltage change curve;
Fig. 8 is Rf=5 Ω F2Locate failure PCC point residual voltage change curve;
Fig. 9 is Rf=5 Ω F2Locate failure 2.15-2.4s PCC point residual voltage change curve;
Figure 10 is Rf=50 Ω F1Locate failure PCC point residual voltage change curve;
Figure 11 is Rf=50 Ω F1Locate failure 2.15-2.4s PCC point residual voltage change curve;
Figure 12 is Rf=50 Ω F1Locate failure 7.15-7.4s PCC point residual voltage change curve;
Figure 13 is Rf=50 Ω F2Locate failure PCC point residual voltage change curve;
Figure 14 is Rf=50 Ω F2Locate failure 2.15-2.4s PCC point residual voltage change curve;
Figure 15 is Rf=100 Ω F1Locate failure PCC point residual voltage change curve;
Figure 16 is Rf=100 Ω F1Locate failure 2.15-2.4s PCC point residual voltage change curve;
Figure 17 is Rf=100 Ω F1Locate failure 7.15-7.4s PCC point residual voltage change curve;
Figure 18 is Rf=100 Ω F2Locate failure PCC point residual voltage change curve;
Figure 19 is Rf=100 Ω F2Locate failure 2.15-2.4s PCC point residual voltage change curve;
Figure 20 is Rf=500 Ω F1Locate failure PCC point residual voltage change curve;
Figure 21 is Rf=500 Ω F1Locate failure 2.15-2.4s PCC point residual voltage change curve;
Figure 22 is Rf=500 Ω F1Locate failure 7.15-7.4s PCC point residual voltage change curve;
Figure 23 is Rf=500 Ω F2Locate failure PCC point residual voltage change curve;
Figure 24 is Rf=500 Ω F2Locate failure 2.15-2.4s PCC point residual voltage change curve;
Figure 25 is Rf=1000 Ω F1Locate failure PCC point residual voltage change curve;
Figure 26 is Rf=1000 Ω F1Locate failure 2.15-2.4s PCC point residual voltage change curve;
Figure 27 is Rf=1000 Ω F1Locate failure 7.15-7.4s PCC point residual voltage change curve;
Figure 28 is Rf=1000 Ω F2Locate failure PCC point residual voltage change curve;
Figure 29 is Rf=1000 Ω F2Locate failure 2.15-2.4s PCC point residual voltage change curve.
Specific embodiment
It is noted that following detailed description is all illustrative, it is intended to provide further instruction to the application.Unless another It indicates, all technical and scientific terms used herein has usual with the application person of an ordinary skill in the technical field The identical meanings of understanding.
It should be noted that term used herein above is merely to describe specific embodiment, and be not intended to restricted root According to the illustrative embodiments of the application.As used herein, unless the context clearly indicates otherwise, otherwise singular Also it is intended to include plural form, additionally, it should be understood that, when in the present specification using term "comprising" and/or " packet Include " when, indicate existing characteristics, step, operation, device, component and/or their combination.
As background technique is introduced, existing mistake/under-voltage isolated island detection method exists in the prior art when isolated island area When DG capacity matches good with load capacity in domain, major network protection front and back PCC point voltage change very little, this variable quantity is not enough to Started/under-voltage protection element, isolated island detects the deficiency that will be failed, and in order to solve technical problem as above, the application is proposed A kind of power distribution network isolated island recognition methods.
In a kind of typical embodiment of the application, a kind of power distribution network isolated island recognition methods is provided, using the present invention The mode active power distribution network schematic diagram of low resistance grounding containing DG of island detection method as shown in Fig. 2,
Wherein major network uses low resistance grounding mode, and DG uses earth-free mode.F1, F2Indicate 2 different location failures Point, wherein F1Between bus and the PCC point of route 1, F2Positioned at route 2.PCC point is L at a distance from bus;Fault point is arrived The distance of major network power supply is L1;The distance of fault point to PCC point is L2。R1It is main net side neutral point to ground resistance, domestic power grid one As be 10 Ω.
Be equipped with breaker (QF) in the outlet of every route, be mainly made of 3 essential parts, i.e., contact, go out Arc system and various buckle releasers, including overcurrent trip, decompression (under-voltage) buckle releaser, thermal trip, shunt release and Automatically jumping device.
PCC point is equipped with voltage transformer, for detecting the residual voltage of PCC point.
Wherein, measurement is generally single phase two-line coil structures with voltage transformer, and original edge voltage is measured voltage, Ke Yidan It mutually uses, V-V shape can also be connected into two and make three-phase use.Voltage transformer primary side is usually multi-tap, to adapt to survey Measure the needs of different voltages.A tertiary coil, referred to as three-winding mutual induction of voltage are also had for protective grounding voltage transformer Device.The tertiary coil of three-phase is connected into open-delta, two exits of open-delta and the pressure-wire of ground(preference) relay Circle is connected.When normal operation, the three-phase voltage of electric system is symmetrical, and the sum of three-phase induction electromotive force on tertiary coil is zero. When singlephase earth fault occurs, neutral point is displaced, and just will detect that residual voltage between the terminal of open delta, and make relay Device movement, to shield to electric system.Residual voltage, which occurs, in coil then just will appear zero sequence magnetic in corresponding iron core It is logical.For this purpose, this threephase potential transformer is using return yoke formula iron core (10KV and following) or uses three single-phase potential transformers.
In order to enable those skilled in the art can clearly understand the technical solution of the application, below with reference to tool The technical solution of the application is described in detail in the embodiment and comparative example of body.
F1Singlephase earth fault occurs for point:
With F1For A phase ground fault occurs for point, failure excessive resistance R is consideredf.Before major network protection act, containing rotary-type DG low resistance grounding mode distribution net work earthing fault compound sequence network is as shown in Figure 3.In figure: ZS(1)And ZS(2)Respectively major network power supply With the sum of the positive sequence of transformer, negative sequence impedance, ZS(1)=ZS(2);ZS(0)For major network Zero-sequence Impedance for Earthing Transformer;ZTSimultaneously for the side DG Net transformer impedance;ZL1(1)And ZL1(2)Respectively fault point is to the route positive sequence of major network power supply, negative sequence impedance, ZL1(1)=ZL1(2); ZL2(1)And ZL2(2)Respectively fault point is to the route positive sequence of PCC, negative sequence impedance, ZL2(1)=ZL2(2);ZL1(0)And ZL2(0)Respectively Fault point is to major network power supply, the route zero sequence impedance of PCC;ZDG(1)And ZDG(2)The positive sequence of respectively rotary-type DG, negative sequence impedance;The respectively positive sequence of major network side and the side DG, negative phase-sequence, zero-sequence fault electricity Stream;For positive (negative or zero) the sequence electric current in fault point, it is equal to current in the fault point1/3;Arrow illustrates the reference side of each electric current To;For fault point additional voltage source;ZNFor the side DG neutral point zero sequence impedance over the ground, when DG is earth-free, | ZN|→∞; For the equivalent capacity in isolated island.
The positive sequence of major network side, negative phase-sequence, zero sequence impedance Za(1)、Za(2)、Za(0)It is respectively as follows:
The positive sequence of the side DG, negative phase-sequence, zero sequence impedance Z 'a(1)、Z’a(2)、Z’a(0)It is respectively as follows:
Current in the fault point under DG grid connection stateAre as follows:
In view of the DG capacity in access power distribution network is smaller, grid-connected transformer and DG direct impedance are generally large, and DG The zero sequence impedance Z ' of sidea(0)For a biggish value, therefore generally have:
Current in the fault point at this time:
Major network side, the side DG zero-sequence current Ia(0), I 'a(0)The zero-sequence current and each side neutral point for being both each side line road are over the ground Zero-sequence current (neutral point to earth-current 1/3), can indicate are as follows:
At this point, PCC point residual voltage are as follows:
When singlephase earth fault occurs for system, after major network protection act, circuit breaker Q F1 tripping, the compound sequence of system Net is as shown in Figure 4.At this point, DG is formed together isolated island together with the load of surrounding.
At this point, PCC point residual voltage are as follows:
F2Singlephase earth fault occurs for point:
It can similarly analyze and obtain, as system F2When A phase ground fault occurs for point, PCC point zero sequence electricity before major network protection act Pressure is still a biggish numerical value.After major network protection act, route 1 restores normal operating condition, is theoretically free of in route There is a residual voltage, consider that error influences, PCC point residual voltage is within the scope of one close to zero at this time.
Excessive resistance R is taken respectivelyf=5 Ω, 50 Ω, 100 Ω, 500 Ω, 1000 Ω, L=20km, L1=10km, L2= 10km.R carries out ground fault modeling and simulating, F to the low resistance grounding mode power distribution network containing DG1And F2Single-phase earthing event occurs for place Hinder major network protection front and back PCC point residual voltage curve graph as shown in Fig. 5-Figure 29.
The specific working principle is as follows for system in above-mentioned Fig. 2:
When systems are functioning properly, circuit breaker Q F1, QF2 is failure to actuate, and PCC point residual voltage is always zero.
When singlephase earth fault occurs for system and fault point is located in isolated island region, before circuit breaker Q F1 tripping, PCC point residual voltage amplitude is more than or equal to Uset1;QF1 tripping after a period of time, PCC point residual voltage continue exist and It sports on the basis of originally more than or equal to Uset2Numerical value, can determine that form isolated island at this time according to the present invention.
When fault point is located at outside isolated island region, before circuit breaker Q F2 tripping, PCC point residual voltage amplitude is greater than etc. In Uset3;QF2 tripping after a period of time, PCC point residual voltage are less than Uset4, in the range of close to zero, according to this hair Bright can determine that cuts off failure at this time.
To sum up, when singlephase earth fault occurs for system and fault point is located in isolated island region, PCC before major network protection act The amplitude for the secondary side residual voltage that point voltage transformer detects is more than or equal to threshold value Uset1(Uset1=105.7V);Major network Isolated island is formed after protection act, PCC point residual voltage persistently has and sport on the basis of the original bigger numerical value, mutation Amplitude afterwards is more than or equal to threshold value Uset2(Uset2=2559V).
When fault point is located at outside isolated island region, the amplitude of PCC point residual voltage is more than or equal to door before major network protection act Limit value Uset3(Uset3=75.84V);The amplitude of PCC point residual voltage is sported less than threshold value U after major network protection actset4 (Uset4=15V) numerical value, in the range of close to zero.
The foregoing is merely preferred embodiment of the present application, are not intended to limit this application, for the skill of this field For art personnel, various changes and changes are possible in this application.Within the spirit and principles of this application, made any to repair Change, equivalent replacement, improvement etc., should be included within the scope of protection of this application.

Claims (9)

1. a kind of power distribution network isolated island recognition methods, characterized in that be primarily adapted for use in major network using low resistance grounding mode, distribution Power supply uses the active power distribution network of earth-free mode, by the change for detecting distributed generation resource grid entry point, that is, PCC point residual voltage Change to carry out isolated island detection, comprising:
If PCC point residual voltage is always zero, system normal operation does not break down at this time;
If detecting, PCC point residual voltage amplitude is at a time sported by 0 more than or equal to threshold value Uset3Value, then at this When etching system occur singlephase earth fault;
After failure continues for some time, if detecting, PCC point residual voltage continues to exist and is being more than or equal to threshold value Uset1Base Bigger value is sported on plinth again, the amplitude after mutation is more than or equal to threshold value Uset2, then fault point is located at isolated island area at this time In domain, and system major network protection act after the failure occurred, form isolated island;
If detecting, PCC point residual voltage amplitude is more than or equal to U by the larger value beforeset3It sports and is less than threshold value Uset4's Value, then fault point is located at outside the isolated island region at this time, and system major network protection act after the failure occurred, cuts off failure, In, Uset2>Uset1>Uset3>Uset4
The power distribution network isolated island recognition methods is complementary with existing mistake/under-voltage isolated island detection method content, when single-phase connect occurs for system When earth fault and PCC dotted line voltage magnitude exceed preset normal operation range, no matter fault point is located in isolated island region Or outside isolated island region, mistake/under-voltage detection method can quickly detect isolated island;
When fault point is located in isolated island region and DG capacity matches well with load capacity in isolated island region, mistake/under-voltage protection member When part tripping, since failure is not yet removed, PCC point residual voltage persistently exists, and accurately examines in mistake/under-voltage detection method failure Isolated island is measured, DG is distributed generation resource.
2. a kind of power distribution network isolated island recognition methods as described in claim 1, characterized in that the active power distribution network is in every line It is circuit breaker Q F1, QF2 that the outlet on road, which is equipped with circuit breaker Q F, and PCC point is equipped with voltage transformer, for detecting PCC point Residual voltage, circuit breaker Q F1 are located at 1 outlet of route, and circuit breaker Q F2 is located at 2 outlet of route.
3. a kind of power distribution network isolated island recognition methods as claimed in claim 2, characterized in that major network is adopted in the active power distribution network With low resistance grounding mode, DG uses earth-free mode, and route 1, route 2, major network power supply are connected to bus, and PCC point is located at On route 1, F1, F2Indicate 2 different location fault points, wherein F1Between route 1 and PCC point, F2Positioned at route 2, PCC Point is L at a distance from bus;Fault point F1Distance to bus is L1;Fault point F1Distance to PCC point is L2, R1For main net side Neutral point is to ground resistance.
4. a kind of power distribution network isolated island recognition methods as claimed in claim 3, characterized in that when systems are functioning properly, open circuit Device QF1, circuit breaker Q F2 are failure to actuate, and PCC point residual voltage is always zero.
5. a kind of power distribution network isolated island recognition methods as claimed in claim 4, characterized in that when singlephase earth fault occurs for system And fault point, when being located in isolated island region, before circuit breaker Q F1 tripping, PCC point residual voltage amplitude is more than or equal to Uset1;Through QF1 tripping after a period of time, PCC point residual voltage persistently exist and are sported on the basis of the original more than or equal to Uset2's Numerical value can determine that and form isolated island at this time.
6. a kind of power distribution network isolated island recognition methods as claimed in claim 4, characterized in that when fault point is located at outside isolated island region When, before circuit breaker Q F2 tripping, PCC point residual voltage amplitude is more than or equal to Uset3;QF2 tripping after a period of time, PCC point residual voltage is less than Uset4, in the range of close to zero, can determine that and cut off failure at this time.
7. a kind of power distribution network isolated island recognition methods as claimed in claim 4, characterized in that in F1Singlephase earth fault occurs for point, Before obtaining major network protection act, obtained according to the distribution net work earthing fault compound sequence network figure containing rotary-type DG low resistance grounding mode To the positive sequence of major network side, negative phase-sequence, zero sequence impedance and the positive sequence of the side DG, negative phase-sequence, zero sequence impedance, and DG grid connection state is calculated accordingly Under current in the fault point, and obtain PCC point residual voltage accordingly, when singlephase earth fault occurs, after major network protection act, Circuit breaker Q F1 tripping, at this point, DG is formed together isolated island together with the load of surrounding.
8. a kind of power distribution network isolated island recognition methods as claimed in claim 7, characterized in that the event in the case where calculating DG grid connection state When barrier point electric current, it is contemplated that the DG capacity in access power distribution network is smaller, and grid-connected transformer and DG direct impedance are generally large, and The zero sequence impedance Z ' of the side DGa(0)For a biggish value, therefore have:
Wherein, Za(1)、Za(2)、Za(0)The respectively positive sequence, negative phase-sequence of major network side, zero sequence impedance, Z 'a(1)、Z’a(2)、Z’a(0)Respectively The positive sequence of the side DG, negative phase-sequence, zero sequence impedance.
9. a kind of power distribution network isolated island recognition methods as claimed in claim 3, characterized in that as system F2Point occurs A phase and is grounded event When barrier, PCC point residual voltage is still a biggish numerical value before major network protection act, and after major network protection act, route 1 restores Normal operating condition does not contain residual voltage theoretically in route, consider that error influences, PCC point residual voltage is at one at this time Close within the scope of zero.
CN201710093512.0A 2017-02-21 2017-02-21 A kind of power distribution network isolated island recognition methods Active CN106684844B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201710093512.0A CN106684844B (en) 2017-02-21 2017-02-21 A kind of power distribution network isolated island recognition methods

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201710093512.0A CN106684844B (en) 2017-02-21 2017-02-21 A kind of power distribution network isolated island recognition methods

Publications (2)

Publication Number Publication Date
CN106684844A CN106684844A (en) 2017-05-17
CN106684844B true CN106684844B (en) 2018-12-04

Family

ID=58861291

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201710093512.0A Active CN106684844B (en) 2017-02-21 2017-02-21 A kind of power distribution network isolated island recognition methods

Country Status (1)

Country Link
CN (1) CN106684844B (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107328981B (en) * 2017-08-11 2020-01-10 华北电力大学 Method for analyzing fault voltage of neutral point of transformer
CN108802567B (en) * 2018-06-01 2021-08-10 国网浙江省电力有限公司宁波供电公司 Island monitoring method for new energy power supply

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103296643A (en) * 2013-03-19 2013-09-11 昆明理工大学 Comparative isolated island detection and protection method based on wide range information phase difference
CN103412207A (en) * 2013-07-11 2013-11-27 华北电力大学(保定) Photovoltaic grid connected inverter island detection method based on negative sequence current injection
CN104779641A (en) * 2012-12-05 2015-07-15 江苏省电力公司常州供电公司 Distributed energy island detection method of automatic safety control system
CN104793148A (en) * 2015-04-30 2015-07-22 国家电网公司 Distributed power source island detecting method based on grid-tied point characteristic harmonic wave voltage measurement
CN106026160A (en) * 2016-03-17 2016-10-12 国家电网公司 Distributed photovoltaic generation anti-islanding protective device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104779641A (en) * 2012-12-05 2015-07-15 江苏省电力公司常州供电公司 Distributed energy island detection method of automatic safety control system
CN103296643A (en) * 2013-03-19 2013-09-11 昆明理工大学 Comparative isolated island detection and protection method based on wide range information phase difference
CN103412207A (en) * 2013-07-11 2013-11-27 华北电力大学(保定) Photovoltaic grid connected inverter island detection method based on negative sequence current injection
CN104793148A (en) * 2015-04-30 2015-07-22 国家电网公司 Distributed power source island detecting method based on grid-tied point characteristic harmonic wave voltage measurement
CN106026160A (en) * 2016-03-17 2016-10-12 国家电网公司 Distributed photovoltaic generation anti-islanding protective device

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
苏州电网并网分布式电源防孤岛的继电保护控制策略研究;范永宇 等;《电力系统保护与控制》;20170116;第45卷(第2期);第94-98页 *

Also Published As

Publication number Publication date
CN106684844A (en) 2017-05-17

Similar Documents

Publication Publication Date Title
Zhalefar et al. A high-speed adaptive single-phase reclosing technique based on local voltage phasors
CN103840437B (en) The quick diagnosis of power distribution network ferromagnetic resonance and singlephase earth fault and processing method
EP2645517B1 (en) Improvement for islanding detection reliability in electricity distribution network
CN204012678U (en) A kind of power distribution network multimode ground protection system
Li et al. Application studies on the active SISFCL in electric transmission system and its impact on line distance protection
CN102067263A (en) Wiring device with leakage detection function
Nashawati et al. Impacts of shunt reactors on transmission line protection
CN106684844B (en) A kind of power distribution network isolated island recognition methods
Paiva et al. Reviewing of anti-islanding protection
CN107785884A (en) A kind of more level active compensation devices of three-phase four-arm and control method
CN102593737A (en) Method for checking and testing relay protection vectors before commissioning of capacitance-compensated transformer substation
CN106856332A (en) A kind of distributed photovoltaic power generation grid-connected system
CN102998582A (en) Detection method of distributing line phase short circuit fault and single phase grounding fault
Horowitz et al. Blackouts and relaying considerations-Relaying philosophies and the future of relay systems
Shen et al. Grounding transformer application, modeling, and simulation
CN109444659A (en) Annular DC distribution net fault detection method based on voltage prediction
CN103928936B (en) For reducing converter and the conversion equipment that transformer is affected by zero-sequence current
CN205786965U (en) The device of a kind of electric power system power generation circuit earthing wire-selecting and comprehensive protector
CN205679686U (en) The external chopper of electric energy meter
Wang et al. Adaptive reclosing strategy for single outgoing line of converter-interfaced wind park using distance relaying algorithm
Nikander Development and testing of new equipment for faulty phase earthing by applying RTDS
CN108649532B (en) Injection type transformer line open-phase protection method and device
CN106505522B (en) A kind of extra-high voltage adjustable transformer differential protecting method
KR20050041625A (en) Detection techniques of line-to-earth fault section in ungrounded network base on distribution automation
CN107332205A (en) A kind of mining flameproof feed switch protection device

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant