CN105067948B - A kind of Small Electric Current Earthing And Routing Device and single phase earth fault detection method - Google Patents
A kind of Small Electric Current Earthing And Routing Device and single phase earth fault detection method Download PDFInfo
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Abstract
The invention discloses a kind of Small Electric Current Earthing And Routing Device and single phase earth fault detection methods, this method is calculated by the synchronized sampling to three-phase bus voltage and three-phase line electric current and least square filter, obtain the size and phase of voltage, electric current, and then it can obtain the phase difference before and after failure, and pass through calculating circuit complex impedance, impedance variations when detecting its failure in real time and pass through the two features, can accurate judgement line single phase grounding failure feature, and do not influenced by direction of tide during looped network.This method provides a kind of new solution for small current grounding fault detection.
Description
Technical field
The present invention relates to a kind of Small Electric Current Earthing And Routing Device and single phase earth fault detection methods.
Background technology
It is well known that the transmission line of electricity of power grid is divided into and directly connecing according to substation transformer neutral grounding mode difference
Ground system and non-direct ground system, ultra-high-tension power transmission line (220kV and more than) belong to solidly grounded system, also referred to as big electricity
Flow earthed system.Low-voltage circuit (110kV and following) belongs to transformer neutral point non-direct ground system, also referred to as low current
Earthed system.Since small current neutral grounding system is responsible for electric power distribution to end user, also referred to as power distribution network, referred to as
Distribution.But since distribution is in densely populated areas, and circuit close building, residential block etc., therefore, also easily by various interference
It causes the accident.According to the national grid stroke analysis of 2015, single-phase earthing accounts for about the 80% of Distribution Network Failure.But due to distribution list
Phase earth fault feature unobvious, the detection and processing of singlephase earth fault are more difficult.For this purpose, national net company is by power distribution network
Singlephase earth fault Processing Technology Research is classified as key issues in 2015.This illustrate distribution phase-to-ground fault detection always not from
Fundamentally solve.The processing method generally used at present is the method for operating a switch, that is, after singlephase earth fault occurs, due to that cannot sentence
Which line fault disconnected is, therefore, person on duty takes test method(s) of operating a switch one by one, if after certain circuit is operated a switch, phenomenon of the failure
It disappears, then illustrates failure on this circuit.This method has seriously affected the power supply quality of resident, also affects grid company
Power supply reliability index.
In terms of fault signature, failure phase earth current is small after single-phase earthing occurs for small current system, and A, B, C three-phase phase are not
Become, field device for a period of time (within regulatory requirements 2 hours), can increase the reliability of power supply in this way with continuous service.But
It is in order to which failure is made to eliminate rapidly, reduces failure face, it is desirable to find in time and cut off faulty line.From the end of the fifties in last century
The beginning of the sixties, First small current system earthing line selecting device in China's was succeeded in developing, and small current line selection equipment has gone through tens
The trials and hardships in year.But actual field operation result shows that the route selection effect of this Small Electric Current Earthing And Routing Device is unsatisfactory.
Large quantities of power workers are still dedicated to improving the research of route selection accuracy rate.
From testing principle, at present detect small current neutral grounding method mainly have steady-state component method, harmonic component method, temporarily
State method, wavelet method.Wherein, steady-state component method, it is that zero-sequence current is lied prostrate than execution, zero-sequence current phase comparing method and group's ratio to be divided into
Phase comparing method.This method is numerically equal to the sum of non-fault line zero-sequence current using the zero-sequence current of faulty line, i.e. event
The zero-sequence current for hindering circuit is maximum.Thus faulty line is found out by comparing the amplitude of circuit zero-sequence current.This method is
A kind of ideal method in laboratory has with short, the laod unbalance of each outlet each circuit in scene, used
For current transformer (TA) nor complete equipilibrium, the circuit for resulting in zero-sequence current maximum in this way differs that establish a capital be faulty line.
Some everybody other than carrying out amplitude com parison and adds phase bit comparison based on above, because of faulty line and non-fault line phase
Position is opposite, thus compensates for the unbalanced influence of outlet.Improve the accuracy of route selection.It is but big for from inside the device
Family is typically all circle collection to the sampling of failure amount, exactly divides acquisition several times that just the calculating data of all outlets have been acquired
Finish, be exactly not acquire the failure amount of all outlets completely in synchronization in this way there is a drawback, be easy for missing
Sentence, the system that this method is not suitable for grounding through arc yet.
The methods of harmonic component method is divided into as 5 subharmonic size and Orientations, each harmonic quadratic sum.But 5 subharmonic contents
It is too small, it is impossible to effectively to be judged, this is just into the bottleneck of this method.
Transient state route selection method, half-wave method and wavelet analysis method headed by being divided into.First half-wave method is to be happened at phase voltage based on ground connection
Close to maximum instantaneous this it is assumed that at this time failure phase capacitance charge by failure phase line road direction trouble point discharge, utilize fault wire
The characteristics of road transient zero-sequence current and amplitude of voltage head half-waves and different from normal condition direction, realizes route selection.But this side
Method is existing on condition that failure must be happened at phase voltage close to maximum value moment.
Wavelet analysis method is to carry out Accurate Analysis to signal using principle of wavelet analysis, particularly to transient signal and faint
Signal is more sensitive, can reliably extract fault signature.Using wavelet transformation one signal can be parsed into different scale and
The sum of small echo of position after being converted using suitable small echo and wavelet basis to transient, easily tells faulty line and non-
Faulty line.
More than four kinds of methods, steady-state component method and wavelet method need the transient characteristic of Synchronization Analysis whole circuit, calculation amount
Very big, this harmonic content is too small because of 5 for Harmonic Method, it is impossible to which effectively detection, transient state route selection method are established on supposed premise, practical use
Less.
In conclusion from testing principle, small current earthing wire-selecting still lacks reliable and effective method.
Invention content
The present invention is to solve the above-mentioned problems, it is proposed that a kind of Small Electric Current Earthing And Routing Device and single phase earth fault detection side
Method, the invention calculate its complex impedance, when distribution line is normal, impedance in real time by Simultaneous Monitoring line voltage distribution and electric current phasor
It is smaller, and voltage current phase relationship is relatively stable, when singlephase earth fault occurs, failure mutually other than normal current, is gone back
It produces to earth-current, impedance changes significantly, and electric current also produces larger difference with voltage-phase.In addition, occur
During single-phase earthing, moment, feature was more obvious during ground connection there are one erratic process.Using this method, without and its
In the case that the feature of its circuit compares, the failure of ground path can be accurately detected.This method not only has very strong applicability,
And amount of calculation is also greatly reduced, make detection device that there is very high cost performance, economic and social benefit is huge.
To achieve these goals, the present invention adopts the following technical scheme that：
A kind of small current neutral grounding single phase earth fault detection method, includes the following steps：
(1) according to the form of expression and testing goal of voltage, current signal, time window and sampling period are determined, is calculated most
Small two multiply wave filter；
(2) voltage, the size of electric current and the phase difference of the two are calculated；
(3) with the phasor value of complex representation voltage and current, complex impedance is calculated；
(4) when the Voltage-current phase difference in former and later two sampling time windows and impedance variations are more than respective threshold
During value, then judge small current grounding fault occurs.
In the step (1), specify the representation of voltage and current signal and the specific method of testing goal is：
The voltage of distribution outlet after voltage transformer and current transformer convert, is represented by following with phase current
Voltage signal with DC component, characteristic component and its harmonic components：
In formula：U0- DC component represents the aperiodic ingredient in signal；
λ-DC component damping time constant；
Uk- kth order harmonic components peak value, k=1 ..., M；
θkThe phase angle of-kth subharmonic；
The π of ω-rotating speed angular frequency, ω=2 f, f -50Hz, network operation frequency, abbreviation power frequency；
U1And θ1The amplitude for corresponding to power frequency and the phase angle relative to sampling time window.
In the step (1), determine that the size of time window and the method in sampling period are：
Time window, refer to CPU single treatments from first sample to the time a last sample
Length, the size T of time windowwTo be equal to the function natural period, sampling period T is less than the function natural period；
Determine the size T of time windowwAnd between sampling period T after, the sample number N in a sample window determines method
For：N and TwAnd the relationship of T is：
In the step (1), the specific method for calculating least square filter is：
By the U of voltage signal0e-λtIt is unfolded by Taylor's radix and takes first two, Uksin(kωt+θk) by trigonometric function exhibition
It opens, then formula (1) is represented by following form：
The function is in sampling instant ti, with its sample u (ti) between it is inevitable equal, that is, sampling equation is：
tiThe sampling instant of-ith；
Due to sampling instant tiIt is known that therefore, sin (k ω t in formula (4)i),cos(kωti) to be known quantity, it will be N number of
Sampling equation is listed, and obtain a matrix equation as follows one by one by formula (4), by tiIt is represented with τ：
By coefficient matrix A, known variables matrix X, sampling matrix is represented with U, then matrix equation (5) and can be represented such as
Under：
AX=U (6)
Therefore, A is a N row, and 2 (M+1) row determine parameter matrix, and X is the matrix of variables that one 2 (M+1) row 1 arranges, and U is
What one N row 1 arranged determines parameter matrix, enables 2 (M+1)=N, and A is with regard to a square formation, and highest can recognize that harmonic multiples M=N/2-1,
Meet Shen agriculture sampling thheorem；
According to matrix theory, there are the conditions of inverse matrix A-1 to be for coefficient matrices A：| A | ≠ 0, and A*A-1=I, I are unit
Matrix, i.e. diagonal entry are 1；
Therefore, matrix of unknown parameters to be measured is：
X=A-1·U (7)
A-1As least square filter.
In the step (2), specific method is：Matrix of variables X is,
Use xiThe element of the i-th row of representing matrix X, then：x1=U0, i.e. DC component, and
x3=U1cosθ1, x4=U1sinθ1 (8)
x3It is exactly the X- axial projections of voltage or current phasor, x4For Y- axial projections of shaking, therefore, voltage, electric current peak-to-peak value
For：
The virtual value of voltage or electric current is：
It is relative to the function phase angle of time window starting point：
When distribution line works normally, voltage-phase is ahead of electric current, and phase difference therebetween is：
Δθ0=θ0u-θ0i (11)
Wherein, θ0uAnd θ0iIt is the voltage-phase and electric current obtained according to formula (10) respectively, when single-phase earthing occurs,
Therebetween phase difference is：
Δθ1=θ1u-θ1i (12)
Therefore, the phase change generated during failure is：
Δ θ=Δ θ1-Δθ0 (13)
In the step (3), the process for calculating complex impedance size is specially：
The complex representation form of voltage and current phasor is respectively：
U=Ux+i·Uy (14)
I=Ix+i·Iy (15)
Wherein, UxAnd IxX as in formula (8)3, wherein, UyAnd IyX as in formula (8)4Numerical value.
Complex impedance is：
The size of complex impedance is：
In the step (4), the judgment method of small current grounding fault alarm is, when in former and later two sampling time windows
Voltage-current phase difference and impedance variations be more than respective threshold value when, then send out earth fault alarm, i.e.,：
If | Z | ＞ Z0, and | Δ θ | ＞ θs, then alarm；
Wherein, Z0And θsRespectively impedance settings and phase angle setting value.
A kind of Small Electric Current Earthing And Routing Device based on the above method, including route protection unit and controller, wherein, line
Road protection location includes current potential conversion module and MCU, wherein, the input terminal connection voltage current transformer of route protection unit,
Current potential conversion module by AC signal be converted to MCU can sampled signal, controller include analog-to-digital conversion module, can sampled signal
Digital signal is converted into, MCU calculates least square filter and voltage, the phase difference of electric current, is transmitted to controller, controls
Device calculates complex impedance, judges whether that small current grounding fault occurs.
A kind of Little Current Ground Connection System based on the above method is distributed in including multiple on distribution network transformer substation circuit
Above-mentioned Small Electric Current Earthing And Routing Device and host, host connect each Small Electric Current Earthing And Routing Device, monitor distribution line in real time
Whether break down.
Beneficial effects of the present invention are：
(1) it is more accurate and sensitive to be currently known method for small current earthing wire-selecting method ratio proposed by the present invention；Why say
This method is sensitive and accurate, and reason has two, one is, other methods do not measure and compare the phase relation of electric current and voltage directly,
Positive sequence, negative phase-sequence, zero sequence are obtained only with traditional phase-sequence component method, is a kind of more general three-phase fault judgment method, and it is single
Due to the effect of neutral point direct-to-ground capacitance after phase earth fault, very big change has occurred in the phase of phase current and phase voltage, can
Which direct and accurate judgement, which is, mutually produces SPA sudden phase anomalies.Second, after single-phase earthing, the impedance of circuit by emotional resistance due to
The addition of capacitive reactances and suddenly change, amplitude variation are apparent, therefore easily selection, and other methods are had no using impedance method,
Two kinds of judgements use simultaneously, increase the accuracy and reliability of detection.
(2) small current earthing wire-selecting method proposed by the present invention no longer needs mutually to discriminate failure phase and whole non-faulting one by one
Not, reaction speed is improved；
(3) present invention by calculating circuit complex impedance in real time, impedance variations when detecting its failure, passes through the two spies
Sign, can accurate judgement line single phase grounding failure feature, and do not influenced by direction of tide during looped network；
(4) detection method proposed by the present invention is used, is expected to thoroughly solve the small current neutral grounding problem of distribution, it can be further
The power supply reliability index of power grid is improved, is all of great significance to power grid enterprises and society.
Description of the drawings
Fig. 1 VIPS-100 visual protections and automated system structure chart；
Fig. 2 small current earthing wire-selecting unit principle schematics.
Specific embodiment：
The invention will be further described with embodiment below in conjunction with the accompanying drawings.
For detect distribution line singlephase earth fault, device synchro measure distribution network transformer substation low-pressure side bus three-phase voltage and
The three-phase current of each outlet calculates voltage and current phase difference and its complex impedance per phase in real time, when generation impedance and phase are dashed forward
During change, that is, think singlephase earth fault has occurred.Four steps and method of method to realize the present invention below.
Step 1：Calculate least square filter
Step 2：Calculate the size and phase difference of voltage, electric current
Step 3：Calculate the size of complex impedance
Step 4：Compare Voltage-current phase difference and the impedance variations in former and later two sampling time windows, when more than door
During threshold value, then small current grounding fault alarm is sent out.
The process that the step 1) calculates least square filter is as follows：
First, the representation and testing goal of voltage and current signal are specified.
The voltage of distribution outlet after voltage transformer and current transformer convert, is represented by following with phase current
Voltage signal with DC component, characteristic component and its harmonic components：
In formula：U0- DC component represents the aperiodic ingredient in signal；
λ-DC component damping time constant；
Uk- kth order harmonic components peak value, k=1 ..., M；
θkThe phase angle of-kth subharmonic；
The π of ω-rotating speed angular frequency, ω=2 f, f -50Hz, network operation frequency, abbreviation power frequency.
U1And θ1The amplitude for corresponding to power frequency and the phase angle relative to sampling time window need this method to detect
Major parameter.
Secondly, it is thus necessary to determine that the size of time window and sampling period.
So-called time window, refer to CPU single treatments from first sample to a last sample
Time span.This time span is generally greater than or the natural period equal to function, and for 50Hz signals, function is inherently all
Phase is 20ms, and the size Tw of time window will be equal to the function natural period.Sampling period T is less than the function natural period.
After determining between the size Tw of time window and sampling period T, the sample number N in a sample window is also determined that
.The relationship of N and Tw and T is：
Formula (1) is done following processing by least square filter in order to obtain first：
U0e- λ t in formula (1) by Taylor's radix are unfolded and take first two, Uksin (k ω t+ θ k) is by trigonometric function
Expansion, then formula (1) is represented by following form：
The function is inevitable equal between its sample u (ti) in sampling instant ti, that is, samples equation and be：
tiThe sampling instant of-ith.
Due to sampling instant ti it is known that therefore, sin (k ω ti) in formula (4), cos (k ω ti) are also believed to known
Amount, only U0, λ, Ukcos (θ k), Uksin (θ k) be unknown quantity.If N number of sampling equation is listed one by one by formula (4), and
Obtain a matrix equation (for equation for purpose of brevity, ti is represented with τ) as follows：
If by coefficient matrix A, known variables matrix X, sampling matrix is represented with U, then matrix equation (5) and can table
Show as follows：
AX=U (6)
Therefore, A is a N row, and 2 (M+1) row determine parameter matrix, and X is the matrix of variables that one 2 (M+1) row 1 arranges, and U is
What one N row 1 arranged determines parameter matrix.If enabling 2 (M+1)=N, A is with regard to a square formation, and highest can recognize that harmonic multiples M=
N/2-1 meets Shen agriculture sampling thheorem.
According to matrix theory, there are the conditions of inverse matrix A-1 to be for coefficient matrices A：| A | ≠ 0, and A*A-1=I.I is unit
Matrix, i.e. diagonal entry are 1.
Therefore, matrix of unknown parameters to be measured is：
X=A-1·U (7)
A-1 is least square filter.
The process that step 2) calculates voltage, the size of electric current and phase difference is as follows：
Matrix of variables X in formula (6), (7) is the unknown column matrix on the left of formula (5)：
If use xiThe element of the i-th row of representing matrix X, then：x1=U0, i.e. DC component.
x3=U1cosθ1,x4=U1sinθ1 (8)
x3It is exactly the X- axial projections of voltage or current phasor, x4For Y- axial projections of shaking.Therefore, the peak-to-peak value of voltage, electric current
For：
The virtual value of voltage or electric current is：
It is relative to the function phase angle of time window starting point：
When distribution line works normally, voltage-phase is ahead of electric current, and phase difference therebetween is：
Δθ0=θ0u-θ0i (11)
Wherein, θ0uAnd θ0iIt is the voltage-phase and electric current obtained according to formula (10) respectively.When single-phase earthing occurs,
Therebetween phase difference is：
Δθ1=θ1u-θ1i (12)
Therefore, the phase change generated during failure is：
Δ θ=Δ θ1-Δθ0 (13)
The process that the step 3) calculates complex impedance size is as follows：
The complex representation form of voltage and current phasor is respectively：
U=Ux+i·Uy (14)
I=Ix+i·Iy (15)
Wherein, UxAnd IxX as in formula (8)3, wherein, UyAnd IyX as in formula (8)4Numerical value.
Complex impedance is：
The size of complex impedance is：
The judgment method of step 4) the small current grounding fault alarm is the electricity in former and later two sampling time windows
When piezo-electric stream phase difference and impedance variations are more than respective threshold value, then earth fault alarm is sent out.I.e.：
If | Z | ＞ Z0, and | Δ θ | ＞ θs, then alarm.
Wherein, Z0And θsRespectively impedance settings and phase angle setting value.
The system structure of device is a general-purpose platform, is adaptable to each grade transformer substation.But route protection list therein
It is first then specially devise small current earthing wire-selecting function, it is set specifically for 110kV and following distribution network transformer substation route protection
Meter.System protection unit is divided into main transformer (abbreviation main transformer) protection, route protection, capacitor protection etc. by device type, has
How many a equipment are with regard to how many protection location.All protection locations form a LAN eventually by 100Mbps networks.Often
It is set in a protection location there are two the controller being mutually redundant, intelligent object is linked as one by each controller by TBUS networks
Body.Active and standby controller is located at the both ends of TBUS nets respectively, and during one of controller failure, another controller can be taken over
TBUS.System structure can be found in Fig. 1.
The small current earthing wire-selecting function of the present invention is located in route protection unit.Wherein, each route protection unit is equal
Sample busbar voltage (three-phase) and line current (three-phase) simultaneously.Route protection unit is using number directly sampling and digital processing
Technology, signal sample circuit is referring to Fig. 2.In order to play respective performance advantage, the MCU of route protection unit is responsible for the public affairs of the present invention
The calculating of formula (7), (8), (9), active and standby controller are responsible for the calculating of formula (10)~(17).The network refresh time of TBUS is
20ms can complete a Refresh Data in a power frequency period, ensure that and judge whether that event occurs in a power frequency period
Barrier.
In Fig. 2, the AC signal (u1, u2) from voltage current transformer is converted through current potential, becomes the letter that MCU can be sampled
Number (Vo1, Vo2).MCU has been internally integrated A/D converter, and CPU directly carries out calculation processing to digital signal.Result of calculation passes through
Internal UART port is communicated in a manner of TBUS again to active and standby controller.
Above-mentioned, although the foregoing specific embodiments of the present invention is described with reference to the accompanying drawings, not protects model to the present invention
The limitation enclosed, those skilled in the art should understand that, based on the technical solutions of the present invention, those skilled in the art are not
Need to make the creative labor the various modifications or changes that can be made still within protection scope of the present invention.
Claims (8)
1. a kind of small current neutral grounding single phase earth fault detection method, it is characterized in that：Include the following steps：
(1) according to the form of expression and testing goal of voltage, current signal, time window and sampling period are determined, calculates minimum two
Multiply wave filter；
(2) voltage, the size of electric current and the phase difference of the two are calculated；
(3) with the phasor value of complex representation voltage and current, complex impedance is calculated；
(4) when the Voltage-current phase difference in former and later two sampling time windows and impedance variations are more than respective threshold value
When, then judge small current grounding fault occurs；
Wherein, it specifies the representation of voltage and current signal and the specific method of testing goal is：
The voltage of distribution outlet after voltage transformer and current transformer convert, is represented by following carry with phase current
The voltage signal of DC component, characteristic component and its harmonic components：
In formula：U0- DC component represents the aperiodic ingredient in signal；
λ-DC component damping time constant；
Uk- kth order harmonic components peak value, k=1 ..., M；
θkThe phase angle of-kth subharmonic；
The π of ω-rotating speed angular frequency, ω=2 f, f -50Hz, network operation frequency, abbreviation power frequency；
U1And θ1The amplitude for corresponding to power frequency and the phase angle relative to sampling time window；
Calculate least square filter specific method be：
By the U of voltage signal0e-λtIt is unfolded by Taylor's radix and takes first two, Uksin(kωt+θk) be unfolded by trigonometric function, then
Formula (1) is represented by following form：
The function is in sampling instant ti, with its sample u (ti) between it is inevitable equal, that is, sampling equation is：
tiThe sampling instant of-ith；
Due to sampling instant tiIt is known that therefore, sin (k ω t in formula (4)i),cos(kωti) to be known quantity, by N number of sampling
Equation is listed one by one by formula (4), and obtains a matrix equation as follows, by tiIt is represented with τ：
By coefficient matrix A, known variables matrix X, sampling matrix is represented with U, then matrix equation (5) and can be represented as follows：
AX=U (6)
Therefore, A is a N row, and 2 (M+1) row determine parameter matrix, and X is the matrix of variables that one 2 (M+1) row 1 arranges, and U is one
What N rows 1 arranged determines parameter matrix, enables 2 (M+1)=N, A is with regard to a square formation, and highest can recognize that harmonic multiples M=N/2-1, meet
Shen agriculture sampling thheorem；
According to matrix theory, there are inverse matrix A for coefficient matrices A-1Condition be：| A | ≠ 0, and A*A-1=I, I are unit matrix,
I.e. diagonal entry is 1；
Therefore, matrix of unknown parameters to be measured is：
X=A-1·U (7)
A-1As least square filter.
2. a kind of small current neutral grounding single phase earth fault detection method as described in claim 1, it is characterized in that：In the step (1),
Determine that the size of time window and the method in sampling period are：
Time window, refer to CPU single treatments from first sample to the time span a last sample,
The size T of time windowwTo be equal to the function natural period, sampling period T is less than the function natural period；
Determine the size T of time windowwAnd between sampling period T after, the sample number N in a sample window determines that method is：N with
TwAnd the relationship of T is：
3. a kind of small current neutral grounding single phase earth fault detection method as described in claim 1, it is characterized in that：In the step (2),
Specific method is：Matrix of variables X is,
Use xiThe element of the i-th row of representing matrix X, then：x1=U0, i.e. DC component, and
x3=U1cosθ1,x4=U1sinθ1 (8)
x3It is exactly the X- axial projections of voltage or current phasor, x4For Y- axial projections of shaking, therefore, voltage, electric current peak-to-peak value be：
The virtual value of voltage or electric current is：
4. a kind of small current neutral grounding single phase earth fault detection method as described in claim 1, it is characterized in that：In the step (2),
It is relative to the function phase angle of time window starting point：
When distribution line works normally, voltage-phase is ahead of electric current, and phase difference therebetween is：
Δθ0=θ0u-θ0i (11)
Wherein, θ0uAnd θ0iThe voltage-phase and electric current obtained according to formula (10) respectively, when single-phase earthing occurs, the two it
Between phase difference be：
Δθ1=θ1u-θ1i (12)
Therefore, the phase change generated during failure is：
Δ θ=Δ θ1-Δθ0 (13)。
5. a kind of small current neutral grounding single phase earth fault detection method as described in claim 1, it is characterized in that：In the step (3),
Calculate complex impedance size process be specially：
The complex representation form of voltage and current phasor is respectively：
U=Ux+i·Uy (14)
I=Ix+i·Iy (15)
Wherein, UxAnd IxX as in formula (8)3, wherein, UyAnd IyX as in formula (8)4Numerical value.
Complex impedance is：
The size of complex impedance is：
6. a kind of small current neutral grounding single phase earth fault detection method as described in claim 1, it is characterized in that：In the step (4),
The judgment method of small current grounding fault alarm is, when the Voltage-current phase difference in former and later two sampling time windows and resistance
When resistanceization is more than respective threshold value, then earth fault alarm is sent out, i.e.,：
If | Z | ＞ Z0, and | Δ θ | ＞ θs, then alarm；
Wherein, Z0And θsRespectively impedance settings and phase angle setting value.
7. a kind of Small Electric Current Earthing And Routing Device of the method based on as described in any one of claim 1-6, it is characterized in that：Packet
Route protection unit and controller are included, wherein, route protection unit includes current potential conversion module and MCU, wherein, route protection list
Member input terminal connection voltage current transformer, current potential conversion module by AC signal be converted to MCU can sampled signal, controller
Including analog-to-digital conversion module, can sampled signal be converted into digital signal, MCU calculates least square filter and voltage, electric current
Phase difference, be transmitted to controller, controller calculates complex impedance, judges whether that small current grounding fault occurs.
8. a kind of Little Current Ground Connection System of the method based on as described in any one of claim 1-6, it is characterized in that：Packet
Include multiple Small Electric Current Earthing And Routing Devices and host as claimed in claim 7 being distributed on distribution network transformer substation circuit, host
Each Small Electric Current Earthing And Routing Device is connected, whether real time monitoring distribution line breaks down.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201510415625.9A CN105067948B (en) | 2015-07-15 | 2015-07-15 | A kind of Small Electric Current Earthing And Routing Device and single phase earth fault detection method |
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| CN201510415625.9A CN105067948B (en) | 2015-07-15 | 2015-07-15 | A kind of Small Electric Current Earthing And Routing Device and single phase earth fault detection method |
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| Publication Number | Publication Date |
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| CN105067948A CN105067948A (en) | 2015-11-18 |
| CN105067948B true CN105067948B (en) | 2018-06-12 |
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| CN106154111B (en) * | 2016-06-22 | 2018-09-11 | 南京南瑞继保电气有限公司 | A kind of m-Acetyl chlorophosphonazo occurring source localization method and device |
| CN106443343A (en) * | 2016-09-30 | 2017-02-22 | 国网福建省电力有限公司 | Small-current grounding fault positioning method employing transient zero sequence current |
| CN107015147B (en) * | 2017-04-01 | 2019-08-06 | 山东泰景电力科技有限公司 | A kind of generating set low-frequency oscillation detection method and device |
| CN107037322B (en) * | 2017-04-14 | 2019-12-17 | 积成电子股份有限公司 | power distribution network low-current grounding fault positioning method based on steady-state characteristics |
| CN109103852B (en) * | 2018-03-19 | 2022-09-09 | 中国石油大学(华东) | Single-phase earth fault protection method of small-resistance earth system based on zero-sequence current comparison |
| CN108776284B (en) * | 2018-03-29 | 2020-12-04 | 广东电网有限责任公司惠州供电局 | Single-phase earth fault protection method for small-resistance earth system |
| CN109444565B (en) * | 2018-05-24 | 2020-03-17 | 天津大学 | Single-phase permanent fault identification method based on voltage phase fluctuation characteristics |
| CN110261722B (en) * | 2019-08-06 | 2021-02-02 | 云南电网有限责任公司电力科学研究院 | Single-phase grounding judgment and phase judgment method of neutral point ungrounded system |
| CN111665418A (en) * | 2020-07-17 | 2020-09-15 | 新三科技有限公司 | Method for detecting fault in electric power transmission line |
| CN113466617A (en) * | 2021-06-24 | 2021-10-01 | 西安交通大学 | Small current grounding dynamic intelligent line selection method based on distance clustering |
| CN113721115A (en) * | 2021-09-23 | 2021-11-30 | 国网江苏省电力有限公司连云港供电分公司 | Single-phase earth fault positioning method for neutral point flexible-earthing power distribution network |
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