CN105119255B - Photovoltaic microgrid fault isolation method based on fault state - Google Patents
Photovoltaic microgrid fault isolation method based on fault state Download PDFInfo
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Abstract
For the single-phase grounding fault and instant fault of a power distribution network including a photovoltaic microgrid, the invention discloses a photovoltaic microgrid fault isolation method based on a fault state. The method includes the following steps of (1) partitioning the microgrid; (2) isolating the fault sections; (3) cutting off a single-phase grounding fault wire; and (4) recovering the power supply of fault microgrid partitions. The microgrid is reasonably partitioned, the fault sections are isolated through a boundary switch, and the power-off range is reduced. By the full use of the anti-islanding protection function of a photovoltaic inverter, a fault line is selected through S transform after the photovoltaic power supply and the power grid are isolated, so that the reliability of relay protection and the accuracy of line selection are improved, and the problem that the power distribution network including the photovoltaic power supply is unreliable in relay protection due to the bidirectional flow of power is solved. The photovoltaic microgrid fault isolation method has better protection effects on the single-phase grounding fault and other instant faults in the power distribution network.
Description
Technical field
The present invention relates to a kind of distribution network failure processing method, specifically a kind of photovoltaic micro based on fault case
Failure separation method, belongs to technical field of new energy power generation.
Background technology
With modern electric user to the continuous improvement of power supply continuity and reliability requirement and power supply enterprise to user
The pay attention to day by day of satisfaction, how after power distribution network breaks down, analyzing failure cause, selects fault feeder, isolated fault platform
Area fast recovery of power supply becomes to become more and more important.On the other hand, with industrial expansion, a large amount of nonlinear-loads such as rectification dress
Put, electric arc furnaces, converter plant etc. access electrical network, photovoltaic, wind-force distributed TRT access distribution side, novel load and send out
The access of electric installation will change the structure of power distribution network, and, the unidirectional power flowing of original power distribution network is changed into bidirectional power flow
Move, this protection that will result in power distribution network and fault diagnosis are more complicated.Therefore, how distributed power source fault post analysis are directed to,
How to take suitable relay protecting method, and under fault case distributed power source partition method so that fast quick-recovery distribution
The power supply of net, increasingly becomes the focus of concern.
Photovoltaic, wind-force distributed TRT access distribution side and change the structure of power distribution network, and, by original distribution
The unidirectional power flowing of net is changed into bi-directional power flow, and this protection that will result in power distribution network and fault diagnosis are more complicated.Tradition
The fault of the relay protecting method power distribution network that can not access distributed power source quickly position and eliminate, this can cause power failure
Scope excessive it is difficult to determine the place broken down.When there is unplanned isolated island, distributed power inverter exists and continues simultaneously
The risk of network operation, this will cause a hidden trouble for the overhaul of the equipments under Distribution Network Failure state.
In low and medium voltage distribution network, more than 80% fault is singlephase earth fault, the high current ground connection system with power transmission network
System is different, and the neutral point of power distribution network is generally earth-free, or passes through arc suppression coil and high resistance grounding, is small current neutral grounding system
System, when there is singlephase earth fault, due to short-circuit loop can not be constituted although now line voltage keeps normal, still permissible
For customer power supply more than one hour, but the phase voltage not broken down will raise 1.732 times, the serious insulating properties threatening system
Energy.When accessed in power distribution network photo-voltaic power supply or containing by photo-voltaic power supply, energy storage device and load structure micro-capacitance sensor, distribution
When net occurs earth fault, not only need to be precisely separating the line that is out of order, isolated fault section, and, should quick-recovery be distributed soon
Formula power supply load or the power supply of micro-capacitance sensor internal load, reduce power off time and customer complaint.
Content of the invention
For overcoming the shortcomings of above-mentioned prior art presence, the invention provides a kind of photovoltaic micro event based on fault case
Barrier partition method, it can effectively reduce power failure range when there is singlephase earth fault or transient fault, improve and contain light
The power supply reliability of the power distribution network of volt micro-capacitance sensor.
The present invention solves its technical problem and is adopted the technical scheme that：A kind of photovoltaic micro fault based on fault case
Partition method, is characterized in that, comprises the following steps：
(1) subregion is carried out to micro-capacitance sensor：According to will be micro- containing photovoltaic in power distribution network with the annexation of power distribution network major network
Electrical network carries out subregion, is divided into multiple micro-capacitance sensor subregions, the point of common coupling PCC between each micro-capacitance sensor subregion and higher level's electrical network
Upper installing demarcation switch, is equiped with open delta voltage mutual inductance between each micro-capacitance sensor subregion bus and higher level's electrical network bus
Device, installs three phase current mutual inductors on each load feeder of power distribution network and supply line respectively and a zero-sequence current is mutual
Sensor；
(2) fault section is isolated：When open delta voltage transformer detects singlephase earth fault or overcurrent
During protection act, faulty line is determined by the zero sequence current mutual inductor on circuit, broken down according to faulty line determination
Micro-capacitance sensor subregion and its subordinate's subregion, and fault micro-capacitance sensor subregion is isolated；
(3) singlephase earth fault line is excised：Obtain each load feeder and supply lines in fault micro-capacitance sensor subregion
The three-phase current sampled signal on road, three-phase current signal obtains phase angle and the amplitude of zero-sequence current through S-transformation, selects zero sequence electricity
The three-line of stream amplitude maximum is compared, and selects fault phase line by comparing the phase angle of zero-sequence current, excises single-phase earthing
Fault wire；
(4) fault micro-capacitance sensor partition recovery is powered：By the voltage transformer at fault micro-capacitance sensor subregion demarcation switch,
The current transformer of each feeder line and supply line measures whether also there is fault, when this fault micro-capacitance sensor subregion yet suffers from list
Phase earth fault, singlephase earth fault line is excised by repeat step (3)；When this fault micro-capacitance sensor subregion, to there are other permanent
Property fault, disconnecting its demarcation switch makes subordinate's subregion islet operation, again restores electricity；When in this fault micro-capacitance sensor subregion each
Feeder line and supply line recover normal, in this fault micro-capacitance sensor subregion photo-voltaic power supply DG again access after the time delay T1 time micro-
Electrical network, and close demarcation switch and its subordinate's subregion demarcation switch of this fault micro-capacitance sensor subregion, distribution system is just recovered again
Often power.
Preferably, whether described demarcation switch is directly connected to carry out point according to micro-capacitance sensor subregion bus and higher level's electrical network bus
Level, demarcation switch is divided into 1 to arrive N level demarcation switch, wherein N >=1, and N is natural number.
Preferably, the demarcation switch of described micro-capacitance sensor subregion and transformer station's outlet switch have singlephase earth fault choosing simultaneously
Line and a high-speed reclosure function.
Preferably, described comprised the following steps by the process that the zero sequence current mutual inductor on circuit determines faulty line：
Set up substation cable outlet fault simulation model：Transformer station is set up according to substation cable outlet and distribution network model
Cable outlet fault simulation model, described substation cable outlet fault simulation model includes transformer, in the outlet of transformer
Side is connected with three outlet circuits, all comprises cable run and overhead transmission line, described cable run one end in every outlet circuit
It is connected with transformer, the other end is connected with overhead transmission line one end, the other end of overhead transmission line is hanging, in every outlet circuit all
It is provided with simulated line fault；
Obtain training sample：The different events to bar outlet circuit setting each in substation cable outlet fault simulation model respectively
Barrier distance, different transition resistance and different faults initial phase angle are emulated, and extract the initial traveling wave of electric current of each bar outlet circuit
And transient signal；The amplitude of amplitude, polarity and transient state dominant frequency according to electric current initial traveling wave zero _exit, phase place, are instructed
Practice sample；
BP neural network is trained：Using training sample, BP neural network model is trained；
Obtain modulus maximum and the polarity of electric current initial traveling wave zero _exit：Every outlet circuit of transformer station is arranged
Zero sequence current mutual inductor, is obtained zero mould electric current of each bar circuit, is extracted by wavelet analysis method using zero sequence current mutual inductor
The modulus maximum of initial wavefront and polarity；
Extract transient state dominant frequency amplitude and phase place：Obtain zero mould current temporary state waveform using zero sequence current mutual inductor, by FFT
Algorithm obtains amplitude and the phase place of each bar circuit transient state dominant frequency；
Faulty line is determined by neutral net：By the modulus maximum of the initial current extracting traveling wave, polarity and
The BP neural network that the amplitude of transient state dominant frequency, polarity input train, determines faulty line.
Preferably, the process of setting up of described substation cable outlet fault simulation model comprises the following steps：
The selection of simulation modeling instrument data analysis tool：Simulation modeling instrument selects PSCAD, and data analysis tool selects
Select MATLAB；
Set up substation cable outlet fault simulation model and emulation module：Described substation cable outlet fault simulation mould
Type includes transformer, is connected with three outlet circuits in the outgoing line side of transformer, all comprises cable run in every outlet circuit
And overhead transmission line, described cable run one end is connected with transformer, and the other end is connected with overhead transmission line one end, overhead transmission line another
One end is hanging, is provided with simulated line fault in every outlet circuit；Described emulation module includes cable run module, frame
Empty line module, short trouble and FCM fault control module, cable major insulation fault and trolley line fault setup module；
Simulation parameter is arranged:The setting of PSCAD simulation parameter, cable data, overhead transmission line parameter and failed controller are joined
Number is configured；
Generate substation cable outlet fault simulation model：Foundation according to emulation module generates transformer station with parameter setting
Cable outlet fault simulation model.
Preferably, the described process being isolated fault micro-capacitance sensor subregion comprises the following steps：
Will be all off to the demarcation switch of fault micro-capacitance sensor subregion and its subordinate's subregion demarcation switch；
Trigger photo-voltaic power supply DG and the electrical network that the anti-islanding switch of photo-voltaic power supply DG in this fault micro-capacitance sensor subregion will be switched off
It is attached；
The demarcation switch time delay T2 time of fault micro-capacitance sensor subregion carries out a high-speed reclosure, by this demarcation switch
High-speed reclosure, excises transient fault circuit.
Preferably, described time T2 is 1.5～2.5 seconds.
Preferably, the selection course of described singlephase earth fault line comprises the following steps：
When there is singlephase earth fault, faulty line and the zero-sequence current phase angle difference 180 degree perfecting circuit, collection is a plurality of
The zero sequence current signal of feeder line, sample frequency is 10kHZ；
Current sampling signal is carried out with S-transformation, obtains amplitude and the phase angle of zero-sequence current；
The three-line choosing zero-sequence current amplitude maximum is compared, if the phase angle of a certain phase current and other phase currents
The difference of phase angle exceedes 90 degree of phase angle threshold value, then this circuit is fault phase, if the phase angle of a certain phase current and other phase current phase angles
Difference be less than 90 degree of phase angle threshold value, then this circuit is non-faulting phase.
Preferably, described time T1 is 30 seconds.
Beneficial effects of the present invention are as follows：
Present invention utilizes the thought of micro-capacitance sensor rationalization partition, strong tie in micro-capacitance sensor partitioned area, interregional weak coupling,
Rationally setting protected mode, reduces power failure range, improves power supply reliability.Micro-capacitance sensor is carried out rational subregion, by boundary
Switch isolation fault section, decreases the scope of power failure；The anti-islanding protection function intrinsic by making full use of photovoltaic DC-to-AC converter,
After photo-voltaic power supply is isolated with power distribution network, power distribution network is reverted to traditional Radial network again, can be using traditional event
Barrier selection method, solves the relay protection that the power distribution network containing photo-voltaic power supply caused due to the two-way flow of power insecure
Problem.
The present invention chooses single-phase fault ground path, small current by the S-transformation method of zero-sequence current in failure line selection
After earthed distribution system occurs singlephase earth fault, contain abundant fault message in zero-sequence current fault component, and fault is divided
The phase information of amount is the important evidence judging faulty line.Utilization therefore of the present invention can extract the time frequency analysis of phase information
Instrument S-transformation is as the signal analysis means of failure line selection.Because the capacity of distributed power source is less, it is to short circuit current
Impact will not produce large effect, therefore single-phase fault route selection is carried out using S-transformation method and can accurately select fault phase
Line, improves the reliability of relay protection and the accuracy rate of route selection.
The present invention determines faulty line by the zero sequence current mutual inductor on circuit, and it can solve the problem that current small current neutral grounding
The difficult problem of system route selection, effectively realizes the failure line selection of substation cable outlet and its distribution line.Due to traveling wave route selection
Method is affected larger by fault moment phase angle, is affected less by transition resistance and fault distance；And the route selection side based on transient state dominant frequency
Method is affected larger by transition resistance and fault distance, is affected less by fault moment phase angle；Therefore, the present invention passes through to propose profit
With artificial neural network, faulty line is determined to traveling wave method and transient state dominant frequency method it is achieved that traveling wave method and transient state dominant frequency method two
The mutual supplement with each other's advantages of person, solves the problems, such as that current fault line selection for indirectly grounding power system is difficult, effectively achieves substation cable outlet
And its failure line selection of distribution line.
Brief description
The present invention is further described below in conjunction with the accompanying drawings：
Fig. 1 is method of the present invention flow chart；
Fig. 2 is that the present invention carries out the schematic diagram of subregion to photovoltaic micro；
In figure：PCC0, PCC1 are point of common coupling, and S11, S12 are one-level demarcation switch, and S21 is two grades of demarcation switch, DG
For distributed power source.
Specific embodiment
For the technical characterstic of this programme can be clearly described, below by specific embodiment, and combine its accompanying drawing, to this
Bright it is described in detail.Following disclosure provides many different embodiments or example for realizing the different knots of the present invention
Structure.In order to simplify disclosure of the invention, hereinafter the part and setting of specific examples is described.Additionally, the present invention is permissible
Repeat reference numerals and/or letter in different examples.This repeat to be for purposes of simplicity and clarity, itself does not indicate
Relation between various embodiments and/or setting is discussed.It should be noted that part illustrated in the accompanying drawings is not necessarily to scale
Draw.Present invention omits to the description of known assemblies and treatment technology and process to avoid being unnecessarily limiting the present invention.
As shown in figure 1, a kind of photovoltaic micro failure separation method based on fault case of the present invention, it includes following step
Suddenly：
(1) subregion is carried out to micro-capacitance sensor：According to will be micro- containing photovoltaic in power distribution network with the annexation of power distribution network major network
Electrical network carries out subregion, is divided into multiple micro-capacitance sensor subregions, the point of common coupling PCC between each micro-capacitance sensor subregion and higher level's electrical network
Upper installing demarcation switch, whether described demarcation switch is directly connected to be divided into 1 according to micro-capacitance sensor subregion bus and higher level's electrical network bus
To N level demarcation switch, wherein N >=1, N is natural number；Install between each micro-capacitance sensor subregion bus and higher level's electrical network bus
There is open delta voltage transformer, for detecting singlephase earth fault；On each load feeder and supply line of power distribution network
Install three phase current mutual inductors and a zero sequence current mutual inductor respectively；The demarcation switch of described micro-capacitance sensor subregion and transformer station
Outlet switch has single-phase earth fault line selection and a high-speed reclosure function simultaneously.
(2) fault section is isolated：When open delta voltage transformer detects singlephase earth fault or overcurrent
During protection act, faulty line is determined by the zero sequence current mutual inductor on circuit, broken down according to faulty line determination
Micro-capacitance sensor subregion and its subordinate's subregion, and fault micro-capacitance sensor subregion is isolated.
(3) singlephase earth fault line is excised：Obtain each load feeder and supply lines in fault micro-capacitance sensor subregion
The three-phase current sampled signal on road, three-phase current signal obtains phase angle and the amplitude of zero-sequence current through S-transformation, selects zero sequence electricity
The three-line of stream amplitude maximum is compared, and selects fault phase line by comparing the phase angle of zero-sequence current, excises single-phase earthing
Fault wire.
(4) fault micro-capacitance sensor partition recovery is powered：By the voltage transformer at fault micro-capacitance sensor subregion demarcation switch,
The current transformer of each feeder line and supply line measures whether also there is fault, when this fault micro-capacitance sensor subregion yet suffers from list
Phase earth fault, singlephase earth fault line is excised by repeat step (3)；When this fault micro-capacitance sensor subregion, to there are other permanent
Property fault, disconnecting its demarcation switch makes subordinate's subregion islet operation, again restores electricity；When in this fault micro-capacitance sensor subregion each
Feeder line and supply line recover normal, in this fault micro-capacitance sensor subregion photo-voltaic power supply DG again access after the time delay T1 time micro-
Electrical network, and close demarcation switch and its subordinate's subregion demarcation switch of this fault micro-capacitance sensor subregion, distribution system is just recovered again
Often power, described time T1 is preferably 30 seconds.
Preferably, described comprised the following steps by the process that the zero sequence current mutual inductor on circuit determines faulty line：
Set up substation cable outlet fault simulation model：Transformer station is set up according to substation cable outlet and distribution network model
Cable outlet fault simulation model, described substation cable outlet fault simulation model includes transformer, in the outlet of transformer
Side is connected with three outlet circuits, all comprises cable run and overhead transmission line, described cable run one end in every outlet circuit
It is connected with transformer, the other end is connected with overhead transmission line one end, the other end of overhead transmission line is hanging, in every outlet circuit all
It is provided with simulated line fault；
Obtain training sample：The different events to bar outlet circuit setting each in substation cable outlet fault simulation model respectively
Barrier distance, different transition resistance and different faults initial phase angle are emulated, and extract the initial traveling wave of electric current of each bar outlet circuit
And transient signal；The amplitude of amplitude, polarity and transient state dominant frequency according to electric current initial traveling wave zero _exit, phase place, are instructed
Practice sample；
BP neural network is trained：Using training sample, BP neural network model is trained；
Obtain modulus maximum and the polarity of electric current initial traveling wave zero _exit：Every outlet circuit of transformer station is arranged
Zero sequence current mutual inductor, is obtained zero mould electric current of each bar circuit, is extracted by wavelet analysis method using zero sequence current mutual inductor
The modulus maximum of initial wavefront and polarity；
Extract transient state dominant frequency amplitude and phase place：Obtain zero mould current temporary state waveform using zero sequence current mutual inductor, by FFT
Algorithm obtains amplitude and the phase place of each bar circuit transient state dominant frequency；
Faulty line is determined by neutral net：By the modulus maximum of the initial current extracting traveling wave, polarity and
The BP neural network that the amplitude of transient state dominant frequency, polarity input train, determines faulty line.
Preferably, the process of setting up of described substation cable outlet fault simulation model comprises the following steps：
The selection of simulation modeling instrument data analysis tool：Simulation modeling instrument selects PSCAD, and data analysis tool selects
Select MATLAB；
Set up substation cable outlet fault simulation model and emulation module：Described substation cable outlet fault simulation mould
Type includes transformer, is connected with three outlet circuits in the outgoing line side of transformer, all comprises cable run in every outlet circuit
And overhead transmission line, described cable run one end is connected with transformer, and the other end is connected with overhead transmission line one end, overhead transmission line another
One end is hanging, is provided with simulated line fault in every outlet circuit；Described emulation module includes cable run module, frame
Empty line module, short trouble and FCM fault control module, cable major insulation fault and trolley line fault setup module；
Simulation parameter is arranged:The setting of PSCAD simulation parameter, cable data, overhead transmission line parameter and failed controller are joined
Number is configured；
Generate substation cable outlet fault simulation model：Foundation according to emulation module generates transformer station with parameter setting
Cable outlet fault simulation model.
Preferably, the described process being isolated fault micro-capacitance sensor subregion comprises the following steps：
Will be all off to the demarcation switch of fault micro-capacitance sensor subregion and its subordinate's subregion demarcation switch；
Trigger photo-voltaic power supply DG and the electrical network that the anti-islanding switch of photo-voltaic power supply DG in this fault micro-capacitance sensor subregion will be switched off
It is attached；
The demarcation switch time delay T2 time of fault micro-capacitance sensor subregion carries out a high-speed reclosure, by this demarcation switch
High-speed reclosure, excises transient fault circuit, and described time T2 is preferably 1.5～2.5 seconds.
Preferably, the selection course of described singlephase earth fault line comprises the following steps：
When there is singlephase earth fault, faulty line and the zero-sequence current phase angle difference 180 degree perfecting circuit, collection is a plurality of
The zero sequence current signal of feeder line, sample frequency is 10kHZ；
Current sampling signal is carried out with S-transformation, obtains amplitude and the phase angle of zero-sequence current；
The three-line choosing zero-sequence current amplitude maximum is compared, if the phase angle of a certain phase current and other phase currents
The difference of phase angle exceedes 90 degree of phase angle threshold value, then this circuit is fault phase, if the phase angle of a certain phase current and other phase current phase angles
Difference be less than 90 degree of phase angle threshold value, then this circuit is non-faulting phase.
As shown in Fig. 2 micro-capacitance sensor is divided into micro-capacitance sensor subregion 1, micro-capacitance sensor subregion 1 and micro-capacitance sensor subregion 3 three by the present invention
Area, each micro-capacitance sensor is connected with power distribution network outlet switch by public coupling bus PCC0, according to micro-capacitance sensor subregion and power distribution network
The annexation of bus PCC0, it is S21 that demarcation switch is divided into one-level demarcation switch S11, S12 and two grades of demarcation switch.
At demarcation switch S11, open delta voltage transformer detects generation singlephase earth fault or overcurrent protection is moved
Make, the zero sequence current mutual inductor on circuit determines fault section and breaks down as P1 point it is assumed that determining.Then fault micro-capacitance sensor subregion
1 this grade of demarcation switch S11 and subordinate demarcation switch S21 is all off, whole photo-voltaic power supply DG in this fault micro-capacitance sensor subregion 1
Anti-islanding switch motion, disconnect the connection of photo-voltaic power supply DG and electrical network, this grade of demarcation switch S11 of fault micro-capacitance sensor subregion 1
Time delay carries out a high-speed reclosure for 1.5～2.5 seconds, by this demarcation switch high-speed reclosure, excises instantaneity event
Barrier circuit.
Obtain fault micro-capacitance sensor subregion 1 Nei Ge supply line three-phase current sampled signal, three-phase current signal is through S-transformation
Obtain phase angle and the amplitude of zero-sequence current, select the three-line of zero-sequence current amplitude maximum to be compared, by comparing zero sequence
The phase angle of electric current selects fault phase line, the singlephase earth fault line of the supply line that excision trouble point P1 is located.
Using voltage transformer, each feeder line and supply line's Current Mutual Inductance at micro-capacitance sensor fault subregion demarcation switch S11
Tolerance surveys whether also there is fault, when fault micro-capacitance sensor subregion 1 yet suffers from singlephase earth fault, repeats singlephase earth fault
The step that line is excised；When fault micro-capacitance sensor subregion 1 has other permanent faults, disconnect demarcation switch S11 Hou Ze subordinate
Micro-capacitance sensor subregion 2 islet operation, restores electricity again；When in fault micro-capacitance sensor subregion 1, each feeder line and supply line just recover
Often, the photo-voltaic power supply DG in fault micro-capacitance sensor subregion 1 accesses micro-capacitance sensor after the time delay of 30s again, and closes this grade of subregion
Demarcation switch S11 and subordinate micro-capacitance sensor subregion demarcation switch S21, distribution system recovers normal power supply again.
For the singlephase earth fault in the power distribution network containing photovoltaic micro and transient fault, the invention provides
A kind of effective fault case partition method, micro-capacitance sensor is carried out rational subregion, by demarcation switch isolated fault section, reduces
The scope having a power failure；The anti-islanding protection function intrinsic by making full use of photovoltaic DC-to-AC converter, photo-voltaic power supply is isolated with electrical network
Afterwards, faulty line is chosen by S-transformation, improve the reliability of relay protection and the accuracy rate of route selection, solve containing photovoltaic
The insecure problem of relay protection that the power distribution network of power supply is caused due to the two-way flow of power, the present invention is to the list in power distribution network
Phase earth fault and other transient faults, for example, be struck by lightning, circuit discharges in short-term, strong wind causes wiring in short-term etc. to have preferably
Protected effect.
Present invention utilizes the thought of micro-capacitance sensor rationalization partition, strong tie in micro-capacitance sensor partitioned area, interregional weak coupling,
Rationally setting protected mode, reduces power failure range, improves power supply reliability.Micro-capacitance sensor is carried out rational subregion, by boundary
Switch isolation fault section, decreases the scope of power failure；The anti-islanding protection function intrinsic by making full use of photovoltaic DC-to-AC converter,
After photo-voltaic power supply is isolated with power distribution network, power distribution network is reverted to traditional Radial network again, can be using traditional event
Barrier selection method, solves the relay protection that the power distribution network containing photo-voltaic power supply caused due to the two-way flow of power insecure
Problem.
The present invention employs S-transformation during single-phase fault route selection, and small current neutral grounding distribution system occurs single-phase earthing
After fault, in zero-sequence current fault component, contain abundant fault message, and the phase information of fault component is to judge fault wire
The important evidence on road.Therefore of the present invention selected as fault by the use of the time frequency analyzing tool S-transformation of phase information can be extracted
The signal analysis means of line.The S-transformation of the propositions such as R.G.Stockwell is frequency division when people study non-stationary signal in recent years
One important tool of cloth, as a kind of Time-Frequency Analysis Method, S-transformation is to continuous wavelet transform and Short Time Fourier Transform
Extension, it has the outstanding time frequency analysis ability of wavelet transformation, and by using Fast Fourier Transform (FFT), improves computing speed
Degree.Compared with wavelet transformation, S-transformation not only can extract the amplitude information of primary signal, and can extract phase angle information.By
Less in the capacity of distributed power source, its impact to short circuit current will not produce large effect, therefore adopts S-transformation method
Carry out single-phase fault route selection and can accurately select fault phase line, improve the reliability of relay protection and the accuracy rate of route selection.
The above is the preferred embodiment of the present invention, for those skilled in the art,
Without departing from the principles of the invention, some improvements and modifications can also be made, these improvements and modifications are also regarded as this
Bright protection domain.
Claims (8)
1. a kind of photovoltaic micro failure separation method based on fault case, is characterized in that, comprise the following steps：
（1）Subregion is carried out to micro-capacitance sensor：According to the annexation of power distribution network major network by the micro-capacitance sensor containing photovoltaic in power distribution network
Carry out subregion, be divided into multiple micro-capacitance sensor subregions, the point of common coupling between each micro-capacitance sensor subregion and higher level's electrical network（PCC0、
PCC1）Upper installing demarcation switch, is equiped with open delta electricity between each micro-capacitance sensor subregion bus and higher level's electrical network bus
Pressure transformer, installs three phase current mutual inductors and a zero sequence on each load feeder of power distribution network and supply line respectively
Current transformer；
（2）Fault section is isolated：When open delta voltage transformer detects singlephase earth fault or overcurrent protection
During action, faulty line is determined by the zero sequence current mutual inductor on circuit, determine the micro- electricity breaking down according to faulty line
Net subregion and its subordinate's subregion, and fault micro-capacitance sensor subregion is isolated；
（3）Singlephase earth fault line is excised：Obtain each load feeder and supply line in fault micro-capacitance sensor subregion
Three-phase current sampled signal, three-phase current sampled signal obtains phase angle and the amplitude of zero-sequence current through S-transformation, selects zero sequence electricity
The three-line of stream amplitude maximum is compared, and selects fault phase line by comparing the phase angle of zero-sequence current, excises single-phase earthing
Fault wire；
（4）Fault micro-capacitance sensor partition recovery is powered：By the voltage transformer at fault micro-capacitance sensor subregion demarcation switch, each
The current transformer of feeder line and supply line measures whether also there is fault, when this fault micro-capacitance sensor subregion yet suffers from single-phase connecing
Earth fault, repeat step（3）Singlephase earth fault line is excised；When this fault micro-capacitance sensor subregion has other permanently events
Barrier, disconnecting its demarcation switch makes subordinate's subregion islet operation, again restores electricity；When each feeder line in this fault micro-capacitance sensor subregion
Recover normal with supply line, photo-voltaic power supply in this fault micro-capacitance sensor subregion（DG）Again access micro- electricity after the time delay T1 time
Net, and close demarcation switch and its subordinate's subregion demarcation switch of this fault micro-capacitance sensor subregion, distribution system recovers normal again
Power supply；
Described comprised the following steps by the process that the zero sequence current mutual inductor on circuit determines faulty line：
Set up substation cable outlet fault simulation model：Substation cable is set up according to substation cable outlet and distribution network model
Outlet fault simulation model, described substation cable outlet fault simulation model includes transformer, connects in the outgoing line side of transformer
It is connected to three outlet circuits, in every outlet circuit, all comprise cable run and overhead transmission line, described cable run one end and change
Depressor is connected, and the other end is connected with overhead transmission line one end, and the other end of overhead transmission line is hanging, is respectively provided with every outlet circuit
There is simulated line fault；
Obtain training sample：Respectively to each bar outlet circuit setting different faults in substation cable outlet fault simulation model away from
Emulated from, different transition resistance and different faults initial phase angle, extracted the initial traveling wave of electric current and temporarily of each bar outlet circuit
State signal；The amplitude of amplitude, polarity and transient state dominant frequency according to electric current initial traveling wave zero _exit, phase place, obtain training sample
This；
BP neural network is trained：Using training sample, BP neural network model is trained；
Obtain modulus maximum and the polarity of electric current initial traveling wave zero _exit：Zero sequence is set in every outlet circuit of transformer station
Current transformer, obtains zero mould electric current of each bar circuit using zero sequence current mutual inductor, is extracted initial by wavelet analysis method
The modulus maximum of wavefront and polarity；
Extract transient state dominant frequency amplitude and phase place：Obtain zero mould current temporary state waveform using zero sequence current mutual inductor, calculated by FFT
Method obtains amplitude and the phase place of each bar circuit transient state dominant frequency；
Faulty line is determined by neutral net：By the modulus maximum of the initial current extracting traveling wave, polarity and transient state
The BP neutral net that the amplitude of dominant frequency, polarity input train, determines faulty line.
2. a kind of photovoltaic micro failure separation method based on fault case according to claim 1, is characterized in that, described
Whether demarcation switch is directly connected to be classified with higher level's electrical network bus according to micro-capacitance sensor subregion bus, and demarcation switch is divided into 1 to arrive N
Level demarcation switch, wherein N >=1, N is natural number.
3. a kind of photovoltaic micro failure separation method based on fault case according to claim 1, is characterized in that, described
The demarcation switch of micro-capacitance sensor subregion and transformer station's outlet switch have single-phase earth fault line selection and a high-speed reclosure simultaneously
Function.
4. a kind of photovoltaic micro failure separation method based on fault case according to claim 1, is characterized in that, described
The process of setting up of substation cable outlet fault simulation model comprises the following steps：
The selection of simulation modeling instrument data analysis tool：Simulation modeling instrument selects PSCAD, and data analysis tool selects
MATLAB；
Set up substation cable outlet fault simulation model and emulation module：Described substation cable outlet fault simulation model bag
Include transformer, be connected with three outlet circuits in the outgoing line side of transformer, in every outlet circuit, all comprise cable run and frame
Ceases to be busy road, described cable run one end is connected with transformer, and the other end is connected with overhead transmission line one end, the other end of overhead transmission line
Vacantly, every outlet circuit is provided with simulated line fault；Described emulation module includes cable run module, trolley line
Road module, short trouble and FCM fault control module, cable major insulation fault and trolley line fault setup module；
Simulation parameter is arranged:To the setting of PSCAD simulation parameter, cable data, overhead transmission line parameter and failed controller parameter
It is configured；
Generate substation cable outlet fault simulation model：Foundation according to emulation module generates substation cable with parameter setting
Outlet fault simulation model.
5. a kind of photovoltaic micro failure separation method based on fault case according to claim 1, is characterized in that, described
The process that fault micro-capacitance sensor subregion is isolated comprises the following steps：
Will be all off to the demarcation switch of fault micro-capacitance sensor subregion and its subordinate's subregion demarcation switch；
Trigger photo-voltaic power supply in this fault micro-capacitance sensor subregion（DG）The anti-islanding photo-voltaic power supply that will be switched off of switch（DG）With electrical network
It is attached；
The demarcation switch time delay T2 time of fault micro-capacitance sensor subregion carries out a high-speed reclosure, by this demarcation switch once
High-speed reclosure, excises transient fault circuit.
6. a kind of photovoltaic micro failure separation method based on fault case according to claim 5, is characterized in that, described
The T2 time is 1.5 ~ 2.5 seconds.
7. a kind of photovoltaic micro failure separation method based on fault case according to claim 1, is characterized in that, described
The selection course of singlephase earth fault line comprises the following steps：
When there is singlephase earth fault, faulty line and the zero-sequence current phase angle difference 180 degree perfecting circuit, gather a plurality of feeder line
Zero sequence current signal, sample frequency be 10kHZ；
Three-phase current sampled signal is carried out with S-transformation, obtains amplitude and the phase angle of zero-sequence current；
The three-line choosing zero-sequence current amplitude maximum is compared, if the phase angle of a certain phase current and other phase current phase angles
Difference exceed 90 degree of phase angle threshold value, then this circuit is fault phase, if the difference of the phase angle of a certain phase current and other phase current phase angles
Less than 90 degree of phase angle threshold value, then this circuit is non-faulting phase.
8. a kind of photovoltaic micro failure separation method based on fault case according to claim 1, is characterized in that, described
The T1 time is 30 seconds.
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| CN105811469B (en) * | 2016-06-01 | 2018-08-14 | 国网浙江省电力公司电力科学研究院 | A kind of distributed photovoltaic cluster-coordinator optimal control method and system |
| CN106470122B (en) * | 2016-09-20 | 2019-04-02 | 北京汇通金财信息科技有限公司 | A kind of network failure locating method and device |
| CN107656149A (en) * | 2017-07-25 | 2018-02-02 | 许继电气股份有限公司 | A kind of open-delta injection type impedance detection isolated island method of discrimination |
| CN107741544B (en) * | 2017-10-23 | 2019-11-22 | 国网吉林省电力有限公司白山供电公司 | A kind of isolated island detection determination method of distributed photovoltaic power generation system |
| CN109728567A (en) * | 2017-10-30 | 2019-05-07 | 南京市嘉隆电气科技有限公司 | A kind of power distribution network single-phase fault fast recovery of power supply method |
| CN108649825B (en) * | 2018-04-25 | 2020-03-27 | 上海海事大学 | Multi-fault isolation method for cascaded multi-level inverter |
| CN108802569A (en) * | 2018-06-14 | 2018-11-13 | 贵州电网有限责任公司 | Distribution circuit single-phase earth fault positioning based on voltage and current type and partition method |
| CN109361200B (en) * | 2018-11-26 | 2020-09-01 | 广东电网有限责任公司 | Fault fast switching positioning method and related device and fault isolation system |
| CN109449982A (en) * | 2018-12-07 | 2019-03-08 | 国网山西省电力公司临汾供电公司 | The operation and maintenance method of power distribution network containing multiple photovoltaic micros |
| CN110456227B (en) * | 2019-08-22 | 2021-01-29 | 清华大学 | Single-ended traveling wave distance measurement method for distribution line |
| CN110967594A (en) * | 2019-11-08 | 2020-04-07 | 广东电网有限责任公司 | Method and device for positioning faults of power distribution network containing inverter type distributed power supply |
| CN111030058B (en) * | 2019-11-28 | 2023-03-31 | 南京国电南自电网自动化有限公司 | Power distribution network partition protection method based on 5G communication |
| CN111579921A (en) * | 2020-05-13 | 2020-08-25 | 南京新唐电力工程有限公司 | Relay protection debugging method |
| CN112072656B (en) * | 2020-09-14 | 2022-04-08 | 阳光电源(南京)有限公司 | Microgrid fault processing method and centralized monitoring system |
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