CN109917230A - The neutral point monitoring and protecting integral method of distribution net work earthing fault containing resistance eutral grounding - Google Patents
The neutral point monitoring and protecting integral method of distribution net work earthing fault containing resistance eutral grounding Download PDFInfo
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Abstract
The invention discloses the neutral point monitoring and protecting integral methods of distribution net work earthing fault containing resistance eutral grounding; when neutral resistance branch current magnitudes or waveform variable quantity are in threshold value section and are continued above predetermined time period, judge that power distribution network insulation against ground exception occurs and alarms；When the phase difference between neutral resistance branch current magnitudes, outlet branch zero-sequence current amplitude and the zero-sequence current and neutral resistance branch current is all satisfied preset condition, then judge that the outlet branch ground fault occurs and alarms or trip.Using method disclosed by the invention, it can insulate in power distribution network and decline early warning early when appearance is slightly discharged, be disposed convenient for timely, avoid the more serious ground connection of generation or phase-to phase fault；Include the high resistance earthing fault that fault resstance is up to 1000 Europe for the discharging fault having occurred and that, then faulty line is recognized accurately, takes quickly excision measure isolated fault, realize the sensitive reliably protecting of distribution net work earthing fault.
Description
Technical field
The present invention relates to power distribution network monitoring and protection technique fields, and in particular to neutral point power distribution network containing resistance eutral grounding ground connection
Malfunction monitoring protects integral method.
Background technique
Neutral grounding in distribution power network include it is earth-free, through grounding through arc, through arc suppression coil parallel resistance ground connection,
Several major ways such as resistance grounded.Outlet in earthing mode of the neutral point containing resistance, usually by being connected on bus
Zero-sequence current protection is configured to reflect the ground fault in outlet；The zero-sequence current protection is using the size of zero-sequence current as movement
Foundation, but must escape All other routes failure when, flows through the capacitive character zero-sequence current of the route, therefore setting valve is higher, in the line
When road itself course of emergency crosses the ground fault of resistance (abbreviation fault resstance), it may occur that action value is not achieved in zero-sequence current numerical value
And the case where miss operation, engineering in practice, occurred repeatedly because of the thing of zero-sequence current protection tripping caused by above-mentioned reason
Therefore.
Do not have since outlet is only configured with zero-sequence current protection reaction ground fault in protective device or switch failure
As back-up protection, single-phase fault may be converted into multiphase failure or cause large area electrical equipment the ground protection of other principles
Scaling loss.In addition, the ground fault of the equipment such as a large amount of distribution line, cable, switchgear is due under ageing equipment, dielectric level
Caused by drop, failure early stage shows as a kind of leakage of very little electric current, then develops into a kind of electric discharge of high current.Power distribution network electricity
Gas equipment is numerous, distribution is wide, it is difficult to go on-line monitoring to draw because of insulation decline in each possible fault point installing sensor
The leakage or electric discharge risen needs to take economic, reliable initial failure monitoring method, finds that the leakage of electrical equipment is put in time
Electricity issues fault pre-alarming signal, takes corresponding countermeasure, and avoiding minor failure development is catastrophe failure
Therefore, be badly in need of it is a kind of high sensitivity, the malfunction monitoring and protected mode of economic and reliable find ground fault in time
And corresponding measure is taken, avoiding minor failure development is catastrophe failure.
Summary of the invention
Therefore, problem to be solved of the present invention is how to find ground fault in time and take corresponding measure, is avoided light
Micro- fault progression is catastrophe failure and is occurring to provide sensitive guarantor when the existing zero-sequence current protection of high resistance grounding is difficult to react
Protective function.
In order to solve the above-mentioned technical problem, present invention employs the following technical solutions:
The neutral point monitoring and protecting integral method of distribution net work earthing fault containing resistance eutral grounding, during this method application scenarios include
Property point using the power distribution network of arc suppression coil parallel resistance ground connection and the power distribution network of the direct resistance grounded of neutral point, including walk as follows
It is rapid:
S101: the electric current of neutral resistance branch is acquired in real time and calculates its amplitude, phase；
S102: when neutral resistance branch current magnitudes or waveform variable quantity are in threshold value section and are persistently surpassed
When crossing predetermined time period, it is judged as that insulation against ground decline or slight electric discharge occurs in the power distribution network, provides ground fault early warning
Signal；
S103: it acquires in real time and calculates each outlet zero-sequence current power frequency amplitude and phase that connect on bus；
S104: the phase difference between each outlet zero-sequence current and neutral resistance branch current is calculated；
S105: when neutral resistance branch current power frequency amplitude, measured outlet branch current power frequency amplitude, go out
When phase difference between line zero-sequence current and neutral resistance branch current is all satisfied preset condition, then the outlet is judged
There is ground fault in branch；
S106: the outlet branch is turned off and controls and provide ground fault alarm.
Preferably, in step S2, providing ground fault pre-warning signal includes generation distribution net work earthing fault warning information, and
The distribution net work earthing fault warning information is sent to operation platform or distribution scheduling center.
Preferably, in step S6, providing ground fault alarm includes the fault message for generating the outlet branch, and is based on
The fault message of the outlet branch is alarmed.
Preferably, the preset condition in step S5 includes:
Neutral resistance branch current power frequency amplitude is greater than first amplitude and adjusts threshold value；
The electric current power frequency amplitude of outlet branch is greater than the second amplitude and adjusts threshold value；
When defining current direction to leave bus is positive direction, the outlet zero-sequence current and neutral point of the outlet branch
Phase difference between ground resistance branch current is greater than the negative of the outlet zero-sequence current of angle adjusting threshold value or the outlet branch
Phase difference between value and neutral resistance branch current is less than the absolute value of (180 degree-angle adjusts threshold value)；
When above-mentioned condition is all satisfied and the duration reaches adjusting movement duration threshold value, judge that the outlet branch occurs
Ground fault.
Preferably, the route of power network neutral point ground resistance earth one end passes through the first Current Transmit 1 and second
For the induction region of Current Transmit 2 to obtain neutral resistance branch current information, every outlet branch of power distribution network is equal
By the induction region of a third Current Transmit 3 to obtain each outlet zero-sequence current information, the first Current Transmit 1
With the input terminal of the output end of the second Current Transmit 2 and third Current Transmit 3 and ground fault detection protective device
It is connected；Ground fault detection protective device includes processor and tripping control element, wherein the control command of tripping control element
Circuit breaker trip circuit is connected, processor is used for the electricity exported based on the first Current Transmit 1 and the second Current Transmit 2
Stream information calculates neutral resistance current amplitude and phase, and processor is also used to when neutral resistance branch current width
When value and phase are in threshold value section and duration reaches failure duration threshold value, judge that ground fault occurs in power distribution network,
Processor is also used to calculate the electric current power frequency amplitude of each outlet branch based on the current information that each third Current Transmit 3 exports
And phase, processor are also used to calculate the outlet zero-sequence current phase difference of each outlet branch, processor is also used to connect in neutral point
Judgement when ground resistance current amplitude, the electric current power frequency amplitude of outlet branch and outlet zero-sequence current phase difference are all satisfied preset condition
There is ground fault in the outlet branch, and tripping control element, which ground fault occurs for outlet branch, to be made to the outlet branch
Carry out breaking processing.
Preferably, processor is also used to when judging that ground fault occurs in the power distribution network, generates distribution net work earthing fault
Warning information, ground fault detection protective device further include communication module, and communication module is for sending the power distribution network ground connection event
Hinder warning information to operation platform or distribution scheduling center.
Preferably, when processor is also used to judge that ground fault occurs in any outlet branch, the outlet branch is generated
Fault message, ground fault detection protective device further include alarm module, and alarm module is for the event based on the outlet branch
Barrier information is alarmed.
Preferably, the current transformer of neutral resistor branch road includes that the first Current Transmit 1 and the second electric current are mutual
Sensor CT2, the upper limit of the precise measurement range of the first Current Transmit 1 are the precise measurement model of the second Current Transmit 2
The lower limit enclosed.
In conclusion the invention discloses the neutral point monitoring and protecting of distribution net work earthing fault containing resistance eutral grounding integration sides
Method acquires the electric current of neutral resistance branch in real time and calculates its amplitude, phase；When neutral resistance branch current
When amplitude or waveform variable quantity are in threshold value section and are continued above predetermined time period, it is judged as that the power distribution network occurs
Insulation against ground decline or slight electric discharge, provide ground fault pre-warning signal；It acquires in real time and calculates each outlet connected on bus
Zero-sequence current power frequency amplitude and phase；Calculate the phase between each outlet zero-sequence current and neutral resistance branch current
Difference；When neutral resistance branch current power frequency amplitude, measured outlet branch current power frequency amplitude, outlet zero-sequence current
When phase difference between neutral resistance branch current is all satisfied preset condition, then judge that the outlet branch connects
Earth fault；The outlet branch is turned off and controls and provide ground fault alarm.It, can using method disclosed by the invention
Event is just issued in time when insulation against ground leakage occurs for other all devices connected on power distribution network bus or slightly discharges over the ground
Hinder early warning, disposed in time convenient for operation maintenance personnel, avoids that more serious ground fault occurs；For through minor failure conversion or suddenly
Metallicity or low resistance (less than 100 Europe) singlephase earth fault or high resistance (100 Europe to 1000 Europe) the single-phase earthing event of generation
Barrier identifies and is out of order outlet and issues the route that control command excision is broken down, to promote power distribution network single-phase earthing guarantor
The reliability and sensitivity of shield.
Detailed description of the invention
In order to keep the purposes, technical schemes and advantages of invention clearer, the present invention is made into one below in conjunction with attached drawing
The detailed description of step, in which:
Fig. 1 is the one of neutral point distribution net work earthing fault containing resistance eutral grounding monitoring and protecting integral method disclosed by the invention
The flow chart of kind specific embodiment；
Fig. 2 is to use neutral point distribution net work earthing fault containing resistance eutral grounding monitoring and protecting integral method disclosed by the invention
When, the connection schematic diagram of the power distribution network of the direct resistance grounded of neutral point；
Fig. 3 is to use neutral point distribution net work earthing fault containing resistance eutral grounding monitoring and protecting integral method disclosed by the invention
When, the connection schematic diagram for the power distribution network that neutral point is grounded using arc suppression coil parallel resistance；
Fig. 4 is a kind of schematic diagram of specific embodiment of ground fault detection protective device in the present invention；
Fig. 5 is route through fault resstance RfIt is grounded zero sequence equivalent figure.
Description of symbols: distribution transformer DT, grounding transformer GT, neutral resistance R0, the first Current Mutual Inductance
Device CT1, the second Current Transmit 2, third current mutual-inductance apparatus CT3, ground fault detection protective device GMP, arc suppression coil
LO, distribution system equivalence direct-to-ground capacitance C0, fault resstance Rf, residual voltage 3U0。
Specific embodiment
The present invention is described in further detail with reference to the accompanying drawing.
As shown in Figure 1, the invention discloses a kind of neutral point distribution net work earthing fault containing resistance eutral grounding monitoring and protecting one
Change method, this method application scenarios include that neutral point is directly passed through using the power distribution network and neutral point of arc suppression coil parallel resistance ground connection
The power distribution network (as shown in Figure 2 or Figure 3) of resistance eutral grounding, includes the following steps:
S101: the electric current of neutral resistance branch is acquired in real time and calculates its amplitude, phase；
In the present invention, analog signal can be obtained from route with Current Transformer, then will be simulated using digital-to-analogue conversion
Signal is converted to digital signal, to calculate amplitude and phase.
S102: when neutral resistance branch current magnitudes or waveform variable quantity are in threshold value section and are persistently surpassed
When crossing predetermined time period, it is judged as that insulation against ground decline or slight electric discharge occurs in the power distribution network, provides ground fault early warning
Signal；
It in the specific implementation, can be electric to acquire neutral ground in the current transformer of milliampere grade using a sensitivity
The current information of resistance, it is 10 milliamperes of Current Transmits 1 to 2 peaces that a precise measurement range, which specifically can be used,.Work as neutral point
Ground resistance current amplitude or Sudden Changing Rate are in threshold value section or earth current wave character meets discharge characteristic matching degree
And duration is when reaching failure duration threshold value, judges that early stage discharge property defect over the ground occurs in power distribution network.
Earth current very little of the electrical equipment grounding failure in the failure premature insulator decline stage, the measurable zero sequence of bus
Voltage very little cannot find such early stage hidden danger by the protection or route selection of residual voltage starting.Therefore during the present invention can be used
Property point resistor current measurement method the low current of milliampere grade is accurately measured by CT1, early stage of the realization to ground fault
Monitoring, and judge whether that ground fault occurs.Calculate the current amplitude I of the neutral resistor branch obtained through CT1CT1, when the electricity
Flow ICT1In threshold value section, (threshold value interval limit is predetermined current threshold ICT1ZD1, the upper limit is predetermined current threshold
ICT1ZD2) in, time duration reaches failure duration threshold value TCT1ZDWhen, then judge that ground fault occurs in power distribution network.
I in the present inventionCT1ZD1Value range is 10 milliamperes to 500 milliamperes, ICT1ZD2Value is that ground fault identifies threshold
Value, value is 500 milliamperes to 2 peaces, by TCT1ZDRange is 1 second to 10 minutes or the longer time.
The present invention constitutes the distribution net work earthing fault initial failure arbitration functions using neutral resistance branch current,
The current information using neutral resistor branch is only needed, can be realized to whether whole controller switching equipments occur what insulation leaked over the ground
Continuous monitoring, avoids and installs insulation monitoring device on a large amount of controller switching equipments, wire and cable, has very high reliability and warp
Ji property.
S103: it acquires in real time and calculates each outlet zero-sequence current power frequency amplitude and phase that connect on bus；
A Current Transmit 3 can be arranged in the present invention on each outlet branch road, for acquiring the electricity of each outlet branch
Stream information, and using the electric current power frequency amplitude and phase for calculating each outlet branch after analog-to-digital conversion.
S104: the phase difference between each outlet zero-sequence current and neutral resistance branch current is calculated；
It is and to judge whether to need to take breaking processing to judge that specific certain outlet is broken down herein.Work as needs
When using open circuit processing, either neutral resistance branch or outlet branch, current transformer can collected electricity
Larger therefore big for accurate response fault current is flowed, the mutual inductance that a precise measurement range is larger current is also set up
Device CT2, such as precise measurement electric current are current transformer of 2 peaces to 1000 peaces, for acquiring neutral resistance branch in real time
The current amplitude and phase on road.Using the different current transformer of two precise measurement ranges, entire power distribution network can be respectively used to
Insulation decline or slight ground fault judge the judgement in stage and specific certain outlet ground fault, and use an electric current mutual
Sensor is compared, and can more preferably guarantee the measurement of the measurement accuracy and high current of low current simultaneously.It can also be protected simultaneously only with one
The current transformer of gamut precision is demonstrate,proved, i.e. CT1 and CT2 are same current transformer.In the specific implementation, if being measured through CT2
The calculated neutral resistance branch current magnitudes of current information and phase be respectively IRM、PRIf the letter measured through CT3
The electric current power frequency amplitude and phase for ceasing calculated outlet branch are respectively IL0、PL0。
S105: when neutral resistance branch current power frequency amplitude, measured outlet branch current power frequency amplitude, go out
When phase difference between line zero-sequence current and neutral resistance branch current is all satisfied preset condition, then the outlet is judged
There is ground fault in branch；
S106: the outlet branch is turned off and controls and provide ground fault alarm.
Each outlet branch road, is mounted on a breaker, can be realized by the breaker to some outlet branch
Open circuit control.
Existing patent and document, which give, some transform neutral point as by isolated neutral or grounding through arc mode
It is former in the selection, different earthing mode selections, earthing wire-selecting of neutral resistor resistance value through resistance or the simultaneously method of resistance eutral grounding
Reason, electrical equipment temperature monitoring, partial discharge monitoring etc. use different methods, but not yet discovery utilizes neutral point electricity
Hinder document of branch current and outlet the zero-sequence current cooperation as the integrated implementation method of ground fault detection protection.
And method disclosed by the invention is used, it can occur accurately to sentence when insulation leakage in the outlet of power distribution network bus connection
Disconnected ground fault out, and when metallicity or resistive singlephase earth fault occurs, it identifies to be out of order outlet and issue control and order
The route for enabling excision break down avoids that safety accident occurs.
Two different current transformers of precise measurement range can be used in the present invention and acquire neutral resistance in real time
Current amplitude and phase, wherein the precise measurement range of the first Current Transmit 1, which is 10 milliamperes to 2, pacifies.Most of ground connection event
Hinder the earth current very little in the failure premature insulator decline stage, the measurable residual voltage very little of bus, by residual voltage
The protection or route selection of starting cannot still find such early stage hidden danger, therefore the present invention can use 1 centering of the first Current Transmit
The low current of property point ground resistance is accurately detected, when neutral resistance current amplitude is located in threshold value section or connects
When earth-current wave character meets discharge characteristic matching degree and duration reaches failure duration threshold value, it is early to judge that power distribution network occurs
Phase insulation against ground decline or discharge property defect can carry out early warning to staff at this time, and staff can be according to early warning to distribution
Net is checked see it is there is insulation weak spot, and be disposed to the defect of discovery, avoiding development of defects is catastrophe failure.
When failure is more serious, either neutral resistance branch or outlet branch, current transformer institute energy are collected
Electric current is larger, therefore, also sets up the Current Transmit 2 for meeting the requirement of high current precise measurement, range may be configured as 2
Pacify to 1000 peaces, acquire the current information of neutral resistance at this time, judges that event occurs in which specific outlet branch
Barrier, and judge whether to need to carry out breaking processing.
It should be noted that the first Current Transmit 1 and the second Current Transmit 2 are mutually indepedent in the present invention
's.May only have the collected information of the first Current Transmit 1 and meet condition in step S2, but the second current transformer
The information of CT2 acquisition is unsatisfactory for the preset condition in step S5, illustrates that power distribution network discharge property over the ground only occurs in early days and lacks at this time
It falls into, at this moment without carrying out breaking processing, it is only necessary to issue early warning, staff is notified to overhaul.It may also be first
The collected information of Current Transmit 1 meets a period of time, staff after the condition in step S2 and does not complete maintenance also
Before, the information of the second Current Transmit 2 acquisition just meets the preset condition in step S5, at this moment, illustrates that failure has been disliked
Change, then needs to carry out breaking processing.It is also possible that the first Current Transmit 1 and the second Current Transmit 2 detect simultaneously
To the current information for meeting respective condition, then illustrate just to need to disconnect the outlet branch of failure when failure occurs.
When it is implemented, providing ground fault pre-warning signal includes generating distribution net work earthing fault early warning letter in step S2
Breath, and the distribution net work earthing fault warning information is sent to operation platform or distribution scheduling center.
After judging that power distribution network breaks down, early warning can be first carried out, is not yet deteriorated in failure, power distribution network can also exert oneself
When strong work, staff is reminded to overhaul in time, or give staff and the sufficient time carry out corresponding counter-measure.
When it is implemented, providing ground fault alarm includes the fault message for generating the outlet branch in step S6, and
Fault message based on the outlet branch is alarmed.
In the present invention, warning device includes but are not limited to, the point on the control panel of operation platform or control centre
Bright malfunction indicator lamp pops up fault message etc. on a display screen.
When it is implemented, the preset condition in step S5 includes:
(1) neutral resistance branch current magnitudes IRThreshold value I is adjusted greater than first amplitudeRMZD, first amplitude adjusting threshold
Value is greater than predetermined current threshold；
Neutral resistance current amplitude IRMIt is zero in the non-failure of route, therefore first amplitude adjusts threshold value IRMZDIt presses
Less than or equal to ICT1ZD2Adjusting forms overlapping relation with ground fault early warning range, such as is set as 500 milliamperes, in this way can be with
So that the sensitivity of reaction failure is very high.
It is also resided in using neutral resistance current amplitude as the advantages of one of protection act condition, for arc blowout wire
Enclose and resistance mode only has arc suppression coil access extinguishing arc and before resistance do not put into, neutral resistance branch current is zero,
Protective device is unsatisfactory for operation condition and is blocked at this time, the malfunction that protective device is likely to occur during avoiding extinguishing arc, guarantees
The reliability of behavior is protected in such cases.
(2) the electric current power frequency amplitude I of outlet branchCT3Threshold value I is adjusted greater than the second amplitudeCT3ZD；
Second amplitude adjusts threshold value ICT3ZDZero sequence current mutual inductance when outlet branch flows through maximum load current is corresponded to by being greater than
The error calculation of device, such as have the calculating of 10% mapping fault by zero sequence current mutual inductor, then it is (0.1* route peak load electricity
Stream)；
(3) the outlet zero-sequence current phase difference of the outlet branch is less than angle adjusting threshold value；
Angle adjusts threshold value PZD0=arctan (R0/XLC)-θk, XLC=XLXC/(XL-XC), XLIt is neutral point arc suppression coil electricity
It is anti-, XCIt is total capacitive reactance that the other equipment direct-to-ground capacitance in addition to route is installed in protection is formed；R0It is neutral resistance；
θkTo adjust margin angle.
This Rule of judgment is only related to arc suppression coil parameter, line distribution capacitance parameter, neutral resistance resistance value, and
Unrelated with the ground resistance resistance value of fault point, therefore, when high resistance earthing fault occurs in route, which has very high reliable
Property.
Under the compensating action of arc suppression coil, XLIt is approximately equal to XC, fault branch electric current and neutral resistor branch current phase
The nearly 180 degree of differential can reliably meet above-mentioned adjusting angle PZD0.Therefore this method is suitable for the ground fault of high resistance value.
(4) when above-mentioned condition is all satisfied and the duration reaches adjusting movement duration threshold value, judge the outlet branch
There is ground fault.
Adjusting acts duration threshold value TCT1ZDIt is calculated by with zero sequence current protection cooperation, is protected in route zero-sequence current
Increase an interval time greater than 0, such as 0.3~0.5 second on the basis of shield actuation time.
In above-mentioned Rule of judgment, only condition (1) is related to condition (2) and current amplitude, and its calculating only needs to consider electric current
The error of mutual inductor, the value very little being calculated, therefore the threshold value for meeting this two conditions is very low.It ensure that on protection philosophy
It can sensitive judgement in very high fault ground resistance, that is, zero-sequence current very little to failure.Open circuit protection i.e. in the present invention can be real
The high resistance earthing protecting of existing distribution line.
When it is implemented, the route of power network neutral point ground resistance earth one end by the first Current Transmit 1 and
For the induction region of second Current Transmit 2 to obtain neutral resistor branch current information, every outlet branch of power distribution network is equal
By the induction region of a third Current Transmit 3 to obtain each outlet zero-sequence current information, the first Current Transmit 1
And second Current Transmit 2 and the output end of third Current Transmit 3 and the input terminal of ground fault detection protective device
It is connected, ground fault detection protective device includes processor and tripping control element, wherein the control command of tripping control element
Circuit breaker trip circuit is connected, processor is used for the electricity exported based on the first Current Transmit 1 and the second Current Transmit 2
Stream information calculates neutral resistance current amplitude and phase, processor be also used to when neutral resistance current amplitude and
When phase is in threshold value section and duration reaches failure duration threshold value, judge that ground fault occurs in power distribution network, handles
Device is also used to calculate the electric current power frequency amplitude and phase of each outlet branch based on the current information that each third Current Transmit 3 exports
Position, processor are also used to calculate the outlet zero-sequence current phase difference of each outlet branch, and processor is also used in neutral ground electricity
When resistance current amplitude, the electric current power frequency amplitude of outlet branch and outlet zero-sequence current phase difference are all satisfied preset condition described in judgement
There is ground fault in outlet branch, and tripping control element, which ground fault occurs for outlet branch, to be made to carry out the outlet branch
Open circuit processing.
When it is implemented, processor is also used to when judging that ground fault occurs in the power distribution network, power distribution network ground connection is generated
Fault pre-alarming information, ground fault detection protective device further include communication module, and communication module connects for sending the power distribution network
Earth fault warning information is to operation platform or distribution scheduling center.
When it is implemented, generating the outlet branch when processor is also used to judge that ground fault occurs in any outlet branch
The fault message on road, ground fault detection protective device further include alarm module, and alarm module is used to be based on the outlet branch
Fault message alarm.
When it is implemented, the first current mutual-inductance apparatus includes the first current transformer and the second current transformer, the first electricity
The upper limit of the precise measurement range of current transformer is the lower limit of the precise measurement range of the second current transformer.
As shown in figure 4, the GMP in ground fault detection protective device, that is, figure, processor, that is, CPU, ground fault detection are protected
Protection unit further includes D/A converter module, memory module etc..AC1, AC2, AC3 are respectively the interface connecting with CT1, CT2, CT3,
Ground fault detection protective device further comprises alarm module, and (tripping module is for controlling correspondence for communication module and tripping module
Outlet branch circuit break).In the present invention, CT1, CT2 can need to be accessed and owned only with a ground fault detection protective device
The CT3 current transducer signal of outlet branch；Or a ground fault detection protection is respectively configured in each outlet branch
Device, it is only necessary to access the current transducer signal of the CT3 of CT1, CT2 and selected outlet branch.
Here the first current transformer and the second current transformer respectively corresponds CT1 and CT2.
Finally, it is stated that the above examples are only used to illustrate the technical scheme of the present invention and are not limiting, although passing through ginseng
According to the preferred embodiment of the present invention, invention has been described, it should be appreciated by those of ordinary skill in the art that can
To make various changes to it in the form and details, without departing from the present invention defined by the appended claims
Spirit and scope.
Claims (8)
1. the neutral point monitoring and protecting integral method of distribution net work earthing fault containing resistance eutral grounding, which is characterized in that this method application
Scene includes that neutral point uses the power distribution network of arc suppression coil parallel resistance ground connection and the power distribution network of the direct resistance grounded of neutral point,
Include the following steps:
S101: the electric current of neutral resistance branch is acquired in real time and calculates its amplitude, phase；
S102: when neutral resistance branch current magnitudes or waveform variable quantity are in threshold value section and are continued above pre-
If when time span, being judged as that insulation against ground decline or slight electric discharge occurs in the power distribution network, providing ground fault pre-warning signal；
S103: it acquires in real time and calculates each outlet zero-sequence current power frequency amplitude and phase that connect on bus；
S104: the phase difference between each outlet zero-sequence current and neutral resistance branch current is calculated；
S105: when neutral resistance branch current power frequency amplitude, measured outlet branch current power frequency amplitude, outlet zero
When phase difference between sequence electric current and neutral resistance branch current is all satisfied preset condition, then the outlet branch is judged
There is ground fault；
S106: the outlet branch is turned off and controls and provide ground fault alarm.
2. neutral point distribution net work earthing fault containing resistance eutral grounding monitoring and protecting integral method as described in claim 1, special
Sign is, in step S2, providing ground fault pre-warning signal includes generation distribution net work earthing fault warning information, and described in transmission
Distribution net work earthing fault warning information is to operation platform or distribution scheduling center.
3. neutral point distribution net work earthing fault containing resistance eutral grounding monitoring and protecting integral method as described in claim 1, special
Sign is, in step S6, providing ground fault alarm includes the fault message for generating the outlet branch, and is based on the outlet
The fault message of branch is alarmed.
4. neutral point distribution net work earthing fault containing resistance eutral grounding monitoring and protecting integral method as described in claim 1, special
Sign is that the preset condition in step S5 includes:
Neutral resistance branch current power frequency amplitude is greater than first amplitude and adjusts threshold value；
The electric current power frequency amplitude of outlet branch is greater than the second amplitude and adjusts threshold value；
When defining current direction to leave bus is positive direction, the outlet zero-sequence current of the outlet branch and neutral ground
Phase difference between resistance branch electric current be greater than the negative value of the outlet zero-sequence current of angle adjusting threshold value or the outlet branch with
Phase difference between neutral resistance branch current is less than the absolute value of (180 degree-angle adjusts threshold value)；
When above-mentioned condition is all satisfied and the duration reaches adjusting movement duration threshold value, judge that the outlet branch is grounded
Failure.
5. neutral point distribution net work earthing fault containing resistance eutral grounding monitoring and protecting integral method as described in claim 1, special
Sign is that the route of power network neutral point ground resistance earth one end passes through the first Current Transmit 1 and the second Current Mutual Inductance
For the induction region of device CT2 to obtain neutral resistance branch current information, every outlet branch of power distribution network passes through one
The induction region of third Current Transmit 3 is to obtain each outlet zero-sequence current information, the first Current Transmit 1 and the second electricity
The output end of current transformer CT2 and third Current Transmit 3 is connected with the input terminal of ground fault detection protective device；Ground connection
Malfunction monitoring protective device includes processor and tripping control element, wherein the control command of tripping control element connects breaker
Trip(ping) circuit, processor are used to calculate based on the current information that the first Current Transmit 1 and the second Current Transmit 2 export
Neutral resistance current amplitude and phase, processor are also used at neutral resistance branch current magnitudes and phase
In in threshold value section and when duration reaches failure duration threshold value, judge that ground fault occurs in power distribution network, processor is also used
The electric current power frequency amplitude and phase of each outlet branch are calculated in the current information exported based on each third Current Transmit 3, is located
Reason device is also used to calculate the outlet zero-sequence current phase difference of each outlet branch, and processor is also used in neutral resistance electric current
Amplitude, the electric current power frequency amplitude of outlet branch and outlet zero-sequence current phase difference judge the outlet branch when being all satisfied preset condition
There is ground fault in road, and tripping control element, which ground fault occurs for outlet branch, to be made to carry out at open circuit the outlet branch
Reason.
6. neutral point distribution net work earthing fault containing resistance eutral grounding monitoring and protecting integral method as claimed in claim 5, special
Sign is that processor is also used to when judging that ground fault occurs in the power distribution network, generates distribution net work earthing fault warning information,
Ground fault detection protective device further includes communication module, and communication module is for sending the distribution net work earthing fault warning information
To operation platform or distribution scheduling center.
7. neutral point distribution net work earthing fault containing resistance eutral grounding monitoring and protecting integral method as claimed in claim 5, special
Sign is, when processor is also used to judge that ground fault occurs in any outlet branch, generates the fault message of the outlet branch,
Ground fault detection protective device further includes alarm module, and alarm module is carried out for the fault message based on the outlet branch
Alarm.
8. neutral point distribution net work earthing fault containing resistance eutral grounding monitoring and protecting integral method as claimed in claim 5, special
Sign is that the current transformer of neutral resistor branch road includes the first Current Transmit 1 and the second Current Transmit 2,
The upper limit of the precise measurement range of first Current Transmit 1 is the lower limit of the precise measurement range of the second Current Transmit 2.
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