CN107272645B - The photovoltaic electric station grid connection fault model and analysis method of Neutral Grounding through Resistance in Electrical - Google Patents
The photovoltaic electric station grid connection fault model and analysis method of Neutral Grounding through Resistance in Electrical Download PDFInfo
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- CN107272645B CN107272645B CN201710508619.7A CN201710508619A CN107272645B CN 107272645 B CN107272645 B CN 107272645B CN 201710508619 A CN201710508619 A CN 201710508619A CN 107272645 B CN107272645 B CN 107272645B
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- G—PHYSICS
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- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B23/00—Testing or monitoring of control systems or parts thereof
- G05B23/02—Electric testing or monitoring
- G05B23/0205—Electric testing or monitoring by means of a monitoring system capable of detecting and responding to faults
- G05B23/0259—Electric testing or monitoring by means of a monitoring system capable of detecting and responding to faults characterized by the response to fault detection
- G05B23/0275—Fault isolation and identification, e.g. classify fault; estimate cause or root of failure
- G05B23/0281—Quantitative, e.g. mathematical distance; Clustering; Neural networks; Statistical analysis
Abstract
The photovoltaic electric station grid connection fault model and analysis method of Neutral Grounding through Resistance in Electrical, based on the inverter failure Equivalent Model with low voltage crossing control strategy, photovoltaic electric station grid connection system containing Neutral Grounding through Resistance in Electrical is modeled, collect the two respective characteristic of class route of route in system line and station for the grid-connected system, establishes calculation of fault model respectively.It can be obtained fault network nonlinear multivariable equation group in conjunction with each sequence network equation of the line fault computation model and corresponding failure boundary condition, then acquire convergence solution with Newton-Laphson iteration construction iterated revision equation, realize accident analysis.Grid-connected photovoltaic power station mostly uses the mode of Neutral Point Through Low Resistance; the present invention solves the problems, such as the fault modeling of the system; the complete analysis line fault that is established as especially collecting line fault computation model in station provides possibility; influence of the neutral resistance to system zero-sequence network is sufficiently taken into account, provides foundation for subsequent design protection.
Description
Technical field
The present invention relates to solar energy power generatings and technical field of electric power transmission, more particularly to a kind of Neutral Grounding through Resistance in Electrical
Photovoltaic electric station grid connection fault model, the photovoltaic electric station grid connection failure based on Neutral Grounding through Resistance in Electrical that the present invention also provides a kind of
The analysis method of model.
Background technique
With being constantly connected to the grid for large-sized photovoltaic power station, electric power system fault incidence inevitably increases, and
Transmission line of electricity short circuit current size is consequently increased, and can exceed that the maximum current ability to bear of certain force devices, thus
Cause cascading failure.Therefore, it is necessary to carry out power grid according to the maximum short circuit current being likely to occur after large-sized photovoltaic electric station grid connection
Construction and improvement.Then, the calculation of fault in the power station containing large-sized photovoltaic, which becomes, develops one of photovoltaic power generation technology top priority.
The case where conventional failure analysis is to large-sized photovoltaic electric station grid connection research is also relatively fewer, and does not account for photovoltaic mostly
The case where Fault Control strategy and Neutral Grounding through Resistance in Electrical in power station, inevitably result in the limitation of calculation of fault.
Summary of the invention
The purpose of the present invention is to provide a kind of photovoltaic electric station grid connection fault model of Neutral Grounding through Resistance in Electrical, the present invention
Another object be to provide a kind of analysis method of photovoltaic electric station grid connection fault model based on Neutral Grounding through Resistance in Electrical.
The present invention realizes that above-mentioned purpose adopts the technical scheme that: a kind of photovoltaic electric station grid connection of Neutral Grounding through Resistance in Electrical
Fault model, including establishing basic model to the photovoltaic electric station grid connection system containing Neutral Grounding through Resistance in Electrical, establishing system line
Road calculation of fault model and collect line fault computation model；It is described in detail below:
(1) based on the inverter failure Equivalent Model with low voltage crossing control strategy, to containing neutral point through resistance
The photovoltaic electric station grid connection system of ground connection establishes basic model；The three-phase output voltage of photovoltaic DC-to-AC converter and three-phase are defeated when including failure
Electric current out；According to the electric current and voltage of the photovoltaic DC-to-AC converter output that instantaneous reactive power theory defines；Three-phase instantaneous active power；
Three-phase instantaneous reactive power；In Voltage Drop, inverter in order to maintain as far as possible output active reactive power stabilization, inversion
Device exports the active and reactive reference value of current reference value and any photovoltaic DC-to-AC converter.
(2) be directed to the photovoltaic electric station grid connection system containing Neutral Grounding through Resistance in Electrical two class routes --- system line and
Collect the respective characteristic of route in standing, accordingly establish system line calculation of fault model and collects line fault computation model.
(3) when failure occurs on system line, entire photovoltaic plant is equivalent to the power supply of a large capacity, and be in
The characteristic of existing voltage-controlled current source, establishes positive and negative zero-sequence network model respectively, and the photovoltaic current source for taking positive sequence to control is containing only positive sequence
Component injects positive sequence network, and negative phase-sequence and zero-sequence network do not contain power supply.
(4) when failure generation collects on route in photovoltaic station, entire photovoltaic station cannot be equivalent to a power supply again,
Will non-failure collect line and failure to collect line difference equivalent.Non- failure collects line and is equivalent to a controlled current source, and failure is converged
Line concentration disconnects from fault point and is equivalent to two power supplys, if fault point is located at cable ZCfOn, then collection bus to failure cable ZCfIt
Between inverter group be equivalent to a controlled current source, ZCfTo the inverter group collected between line end be equivalent to another by
Control current source.Entire grid-connected system will be equivalent to the network of a system power supply and three photo-voltaic power supplies, establish positive negative zero respectively
Sequence network model, each photovoltaic current source inject respective positive sequence short circuit current in positive sequence network, negative phase-sequence and zero-sequence network
Power supply is not contained.
A kind of analysis method of the photovoltaic electric station grid connection fault model based on Neutral Grounding through Resistance in Electrical, it is characterised in that:
The system line calculation of fault model that photovoltaic electric station grid connection fault model step (2) based on Neutral Grounding through Resistance in Electrical is established,
Photo-voltaic power supply is handled as controlled source, in conjunction with the boundary condition of various fault types, it is polynary non-to can be obtained fault network
System of linear equations；Then convergence solution is acquired with Newton-Laphson iteration construction iterated revision equation, realizes accident analysis.With allusion quotation
For type photovoltaic electric station grid connection, such as Fig. 1 network:
(1) when failure occurs on system line, there is positive and negative zero-sequence network such as Fig. 2, then each branch impedance of Fig. 2 is gone here and there
Parallel connection merges, and obtains equivalent network such as Fig. 3 of positive and negative zero sequence.When singlephase earth fault occurs for system line, connect in conjunction with single-phase
Earth fault boundary condition:That is the relationship of the positive and negative residual voltage electric current of grounding point, obtains
System line singlephase earth fault compound sequence network Fig. 4, and then loop current equation group is obtained by the loop method of analysis；WhereinFor fault point positive and negative residual voltage over the ground,For fault point
Positive and negative zero-sequence current.
In formula (1), Ii: the loop current of circuit i；ZS35: 35kV system positive sequence equivalent impedance；ZL351: M bus to fault point
Line impedance between K；ZT: photovoltaic source Equivalent Transformer impedance；ES: 35kV system phase voltage；Photovoltaic electric source voltage terminal；Photovoltaic source fault current；Z∑0: Zero sequence synthetic impedance；P*And Q*The active and idle ginseng of inverter control when for fault traversing z
Examine value.
In conjunction with inverter described in the photovoltaic electric station grid connection fault model step (1) based on Neutral Grounding through Resistance in Electrical
Failure Equivalent Model, the non-linear solve system of equation for establishing system line singlephase earth fault are as follows:
In formula (2), ZS35: 35kV system positive sequence equivalent impedance；ZL351: M bus to the line impedance between the K of fault point；ZT:
Photovoltaic source Equivalent Transformer impedance；Z∑0: Zero sequence synthetic impedance；ES: 35kV system phase voltage；Photovoltaic electric source voltage terminal；
Photovoltaic source fault current；Fault point zero-sequence current；
η is the capacity coefficient of inverter after failure, For photovoltaic electric source voltage terminal positive sequence after failure
Component；ImaxFor inverter maximum allowed current, according to newest standards Imax=1.5In；Sn、UnAnd InFor inverter rated capacity,
Voltage and current；kqFor reactive power support coefficient；P*And Q*Inverter exports active and idle reference value when for failure；WithFor
Inverter exports active and idle reference value when normal operation.
Formula (2) is the solve system of equation of system line singlephase earth fault, is hadFive unknown numbers,
fx=[f1f2f3f4f5]TFive equations, can solve, but due to the non-linear relation of equation, cannot directly acquire analytic solutions,
So acquiring convergence solution with Newton-Laphson iteration construction iterated revision equation, singlephase earth fault analysis is realized.
(2) what the photovoltaic electric station grid connection fault model step (2) based on Neutral Grounding through Resistance in Electrical was established collects route event
Hinder computation model, is further carried out accident analysis；Each branch impedance in the positive and negative zero-sequence network topological diagram 5 of line fault will be collected
Series-parallel merging is done, equivalent network Fig. 6 of positive and negative zero sequence is obtained.
When collecting route generation singlephase earth fault in photovoltaic station, in conjunction with boundary condition:The relationship of positive and negative zero-sequence current voltage at failure, whereinOver the ground for fault point
Positive and negative residual voltage,For the positive and negative zero-sequence current of fault point), i.e. the relationship of the positive and negative residual voltage electric current of grounding point,
It obtains collecting line single phase grounding failure compound sequence network Fig. 7, loop current equation group is obtained by the loop method of analysis；
In formula (3), Ii: the loop current of circuit i；ZS35: 35kV system positive sequence equivalent impedance；ZL35: 35kV line impedance；
ZT40: non-faulting collects line photovoltaic source Equivalent Transformer impedance；ZTm,ZTn1: failure collects line photovoltaic source Equivalent Transformer impedance；
ES: 35kV system phase voltage；Non-faulting collects the equivalent photovoltaic source voltage terminal of line and fault current；Collect
Photovoltaic inversion equivalent source end voltage and fault current between bus and fault point；Fault point is to the light for collecting line end
Lie prostrate inversion equivalent source end voltage and fault current；Z∑0: Zero sequence synthetic impedance；Z∑2: negative phase-sequence comprehensive impedance.
In conjunction with photovoltaic inversion described in the photovoltaic electric station grid connection fault model step (1) based on Neutral Grounding through Resistance in Electrical
Power failure Equivalent Model collects line fault computation model and contains a system power supply and three photo-voltaic power supplies, each photovoltaic
Power supply has the current equation and active reactive equation of oneself, establishes the non-linear solution that photovoltaic collects line single phase grounding failure
Equation group is as follows:
In formula (4)~(7),Fault point zero-sequence current；ZS35: 35kV system positive sequence equivalent impedance；ZL35: 35kV route
Impedance；ZT40: non-faulting collects line photovoltaic source Equivalent Transformer impedance；ZTm,ZTn1: failure collects the resistance of line photovoltaic source Equivalent Transformer
It is anti-；Zm: the cable positive-negative sequence impedance between collection bus and fault point；ZCf1: the line impedance of failure cable；ES: 35kV system phase
Voltage；
Collect line fault computation model to contain there are three photovoltaic current source, each photovoltaic source have oneself current equation and
Active reactive equation:
Non-faulting collects the equivalent photovoltaic source voltage terminal of line and fault current；η40SFor the equivalent photovoltaic inversion electricity
The capacity coefficient in source, WithEquivalent Photovoltaic Inverter output is active and idle when for failure
Reference value；WithInverter exports active and idle reference value when to operate normally.
Photovoltaic inversion equivalent source end voltage and fault current between collection bus and fault point；ηmSFor this etc.
The capacity coefficient of Photovoltaic Inverter is imitated, WithThe equivalent Photovoltaic Inverter is defeated when for failure
Active and idle reference value out；WithInverter exports active and idle reference value when to operate normally.
Fault point is to the photovoltaic inversion equivalent source end voltage and fault current for collecting line end；ηnSIt is equivalent for this
The capacity coefficient of Photovoltaic Inverter, WithThere is equivalent Photovoltaic Inverter output when for failure
Function and idle reference value；WithInverter exports active and idle reference value when to operate normally.
Formula (4)~(7), share 13 equations and
13 unknown numbers equally acquire convergence solution with Newton-Laphson iteration construction iterated revision equation, realize that photovoltaic collects line
The analysis of road singlephase earth fault.
More and more by the way of Neutral Point Through Low Resistance, the present invention is solved through resistance grid-connected photovoltaic power station
The line fault computation modeling problem of the photovoltaic electric station grid connection system of ground connection, especially collects line fault meter in photovoltaic plant station
The completely analysis circuit failure that is established as calculating model provides possibility, has fully considered neutral resistance to grid-connected system
The influence of zero-sequence network acquires short circuit current especially zero-sequence current and node electricity under various fault conditions in which can be convenient
Pressure provides foundation for the design of subsequent protection scheme, and the adjusting and verification especially for route zero-sequenceprotection provide foundation,
Solve the problems, such as that photovoltaic station grid-connected system quickly cuts off ground fault and causes photovoltaic large area off-grid to avoid failure propagation.
Detailed description of the invention
Fig. 1 is the photovoltaic station grid-connected system for the Neutral Grounding through Resistance in Electrical studied in the method for the present invention specific embodiment；
Wherein ZS330: 330kV system impedance；ZL110: 110kV line impedance；ZL35: 35kV line impedance；L1~L5: five
Photovoltaic collects route in station；T1: 330kV main transformer；T2: 110kV step-up transformer；Rg: neutral resistance；ZC1~
ZC10: collect route first segment~ten section cable resistance；1: collecting route protection, 2: system line is protected.
Fig. 2 is the positive and negative zero-sequence network topological diagram of system line failure in the method for the present invention specific embodiment；
(a) (b) (c) is respectively positive and negative zero sequence topological diagram；Wherein330kV system impedance；The positive and negative zero sequence line impedance of 110kV；M bus is to the positive and negative zero sequence between the K of fault point
Line impedance；Positive sequence line impedance between K to the N bus of fault point；330kV main transformer
The positive and negative zero sequence impedance of depressor；330kV main transformer is to ground leg zero sequence impedance；110kV step-up transformer
Positive and negative zero sequence impedance；110kV step-up transformer is to ground leg zero sequence impedance；The positive negative zero resistance of case transformer
It is anti-；The end voltage of photovoltaic current source；Photovoltaic source positive sequence fault current；Positive and negative zero sequence is electric over the ground for fault point
Pressure.
Fig. 3 is each sequence equivalent network figure of system line failure in the method for the present invention specific embodiment；
Wherein,35kV system positive sequence equivalent impedance；
35kV system negative phase-sequence equivalent impedance；The equivalent resistance of 35kV system zero sequence
It is anti-；Rg is neutral resistance；The positive and negative zero-sequence current of fault point.
Fig. 4 is line single phase grounding failure compound sequence network figure in the method for the present invention specific embodiment；
Wherein Ii: the loop current of circuit i；Positive-negative sequence impedance is equal, and 35kV system positive-negative sequence is equivalent
Impedance；Photo-voltaic power supply Equivalent Transformer positive-negative sequence impedance；
Zero sequence synthetic impedance.
Fig. 5 is to collect the positive and negative zero-sequence network topological diagram of line fault in the method for the present invention specific embodiment；
(a) (b) (c) is respectively positive and negative zero sequence topological diagram；Wherein330kV system impedance；The positive and negative zero sequence line impedance of 110kV；The positive and negative zero sequence line impedance of 35kV；The positive and negative zero sequence impedance of 330kV main transformer；330kV main transformer is to ground leg zero sequence impedance；The positive and negative zero sequence impedance of 110kV step-up transformer；110kV step-up transformer is to ground leg zero sequence impedance；Fault point upstream failure cable run impedance；The resistance of trouble point downstream failure cable route
It is anti-；The positive and negative zero sequence impedance of cable between collection bus and fault point；Fault point to collect line end
The positive and negative zero sequence impedance of cable；Non-faulting collects line photovoltaic source Equivalent Transformer positive sequence impedance；Collect fault point upstream
Line photovoltaic source Equivalent Transformer positive sequence impedance；Trouble point downstream collects line photovoltaic source Equivalent Transformer positive sequence impedance；Non-faulting collects the equivalent photovoltaic source voltage terminal of line and fault current；Light between collection bus and fault point
Lie prostrate inversion equivalent source end voltage and fault current；Fault point is electric to the photovoltaic inversion equivalent source end for collecting line end
Pressure and fault current；Rg: neutral resistance；Fault point positive and negative residual voltage over the ground.
Fig. 6 is to collect each sequence equivalent network figure of line fault in the method for the present invention specific embodiment；
Wherein,35kV system positive sequence equivalent impedance；
35kV system negative phase-sequence equivalent impedance；The equivalent resistance of 35kV system zero sequence
It is anti-；The positive and negative zero-sequence current of fault point.
Fig. 7 is to collect line fault single-phase earthing compound sequence network figure in the method for the present invention specific embodiment.
Wherein Ii: the loop current of circuit i；Positive-negative sequence impedance is equal, and 35kV system positive-negative sequence is equivalent
Impedance；35kV line impedance；Cable positive-negative sequence resistance between collection bus and fault point
It is anti-；Fault point upstream failure cable run positive-negative sequence impedance；Collect line in downstream
Photovoltaic source Equivalent Transformer positive sequence impedance；Zero sequence synthetic impedance；Negative phase-sequence comprehensive impedance.
Specific embodiment
A kind of photovoltaic electric station grid connection fault model of Neutral Grounding through Resistance in Electrical, including to containing Neutral Grounding through Resistance in Electrical
Photovoltaic electric station grid connection system establish basic model, establish system line calculation of fault model and collect line fault calculate mould
Type；Specifically:
(1) based on the inverter failure Equivalent Model with low voltage crossing control strategy, to containing neutral point through resistance
The photovoltaic electric station grid connection system of ground connection establishes basic model；The three-phase output voltage of photovoltaic DC-to-AC converter and three-phase are defeated when including failure
Electric current out；According to the electric current and voltage of the photovoltaic DC-to-AC converter output that instantaneous reactive power theory defines；Three-phase instantaneous active power；
Three-phase instantaneous reactive power；In Voltage Drop, inverter in order to maintain as far as possible output active reactive power stabilization, inversion
Device exports the active and reactive reference value of current reference value and any photovoltaic DC-to-AC converter.
(2) be directed to the photovoltaic electric station grid connection system containing Neutral Grounding through Resistance in Electrical two class routes --- system line and
Collect the respective characteristic of route in standing, accordingly establish system line calculation of fault model and collects line fault computation model.
(3) when failure occurs on system line, then entire photovoltaic plant is equivalent to the power supply of a large capacity, and
The characteristic that voltage-controlled current source is presented, is modeled according to positive and negative zero-sequence network, and wherein photovoltaic plant is by the positive negative zero of short circuit current
Order components are injected separately into positive and negative zero-sequence network.
(4) when failure occurs at photovoltaic station when collecting on route, entire photovoltaic station cannot be equivalent to a power supply again,
It re-establishes and collects line fault computation model；If fault point is located at and collects line wherein one section of cable ZCfOn.It does not break down
Collecting line equivalent is a controlled current source, break down that collect route individually equivalent, collection bus is electric to failure
Cable ZCfBetween inverter group be equivalent to a controlled current source, ZCfIt is equivalent to the inverter group collected between line end
One controlled current source, whole system equivalence are the network of power supply more than one, then system power supply and each section impedance are converted
It to collection bus side, is modeled according to positive and negative zero-sequence network, wherein photovoltaic plant divides the positive and negative zero-sequence component of short circuit current
Positive and negative zero-sequence network is not injected.
It is below a kind of point of the photovoltaic electric station grid connection fault model based on Neutral Grounding through Resistance in Electrical provided by the invention
The specific application example of analysis method.
By taking large-sized photovoltaic station (50MW) grid-connected system of a typical Neutral Grounding through Resistance in Electrical as an example, network topology such as Fig. 1.
Photo-voltaic power supply is presented controlled current source characteristic in failure, in engineering, since each generator unit in same photovoltaic station is consistent
Property it is very strong, and determine photovoltaic power intensity of illumination and temperature it is almost the same in same photovoltaic station, it can be assumed that
The power that all parameters of each generator unit are equal, each generator unit is sent in synchronization is consistent.
Therefore, when failure occurs on 35kV system line, entire photovoltaic plant can be equivalent to one big by we
The power supply of capacity.When ground fault occurs, the characteristic of voltage-controlled current source is presented in photovoltaic source, and photovoltaic DC-to-AC converter takes positive sequence control
Strategy, by the positive-sequence component injection network of short circuit current, as shown in Figure 2, it is established that the positive and negative zero-sequence network of system line failure
Model.
When failure generation collects on route in photovoltaic station, entire photovoltaic station cannot be equivalent to a power supply again, needed
It re-establishes and collects line fault computation model.If fault point is located at and collects line wherein one section of cable ZCfOn.4 not broken down
Item collects the controlled current source I that line equivalent is a 40MW40S, break down that collect route individually equivalent, 35kV converges
Collect bus to failure cable ZCfBetween m 1MW inverter group be equivalent to the controlled current source I of a mMWmS, ZCfTo collecting line
N 1MW inverter group between the end of road is equivalent to the controlled current source I of a nMWnS, wherein m+n=10, whole system etc.
Value is the network of power supply more than one, then system power supply and each section impedance is converted to the side 35kV, it is established that photovoltaic collects line
Positive and negative zero-sequence network model such as Fig. 5 of road failure.
System line calculation of fault model based on aforementioned foundation, further progress accident analysis；By system line failure
Series-parallel merging is done in each branch impedance in positive and negative zero-sequence network topological diagram 2, obtains equivalent network Fig. 3 of positive and negative zero sequence.
When singlephase earth fault occurs for system line, in conjunction with singlephase earth fault boundary condition:That is the relationship of the positive and negative residual voltage electric current of grounding point, obtains system line single-phase earthing
Failure compound sequence network Fig. 4, and then loop current equation group is obtained by the loop method of analysis；
WhereinFor fault point positive and negative residual voltage over the ground,For the positive and negative zero-sequence current of fault point.
In formula (1), Ii: the loop current of circuit i；ZS35: 35kV system positive sequence equivalent impedance；ZL351: M bus to fault point
Line impedance between K；ZT: photovoltaic source Equivalent Transformer impedance；ES: 35kV system phase voltage；Photovoltaic electric source voltage terminal；Photovoltaic source fault current；Z∑0: Zero sequence synthetic impedance；P*And Q*The active and idle ginseng of inverter control when for fault traversing
Examine value.
In conjunction with inverter failure Equivalent Model above-mentioned, the non-linear solution of system line singlephase earth fault is established
Equation group is as follows:
In formula (2), ZS35: 35kV system positive sequence equivalent impedance；ZL351: M bus to the line impedance between the K of fault point；ZT:
Photovoltaic source Equivalent Transformer impedance；Z∑0: Zero sequence synthetic impedance；ES: 35kV system phase voltage；Photovoltaic electric source voltage terminal；
Photovoltaic source fault current；Fault point zero-sequence current；
η is the capacity coefficient of inverter after failure, For photovoltaic electric source voltage terminal positive sequence after failure
Component；ImaxFor inverter maximum allowed current, according to newest standards Imax=1.5In；Sn、UnAnd InFor inverter rated capacity,
Voltage and current；kqFor reactive power support coefficient；P*And Q*Inverter exports active and idle reference value when for failure；WithFor
Inverter exports active and idle reference value when normal operation.
Formula (2) is the equation group of system line singlephase earth fault, is hadFive unknown numbers, fx=
[f1f2f3f4f5]TFive equations, can solve, but due to the non-linear relation of equation, cannot directly acquire analytic solutions, so
Convergence solution is acquired with Newton-Laphson iteration construction iterated revision equation, realizes singlephase earth fault analysis.
Likewise, collecting line fault computation model based on aforementioned, it is further carried out accident analysis；Route event will be collected
Hinder each branch impedance in positive and negative zero-sequence network topological diagram 5 and do series-parallel merging, obtains equivalent network Fig. 6 of positive and negative zero sequence.
When collecting route generation singlephase earth fault in photovoltaic station, in conjunction with boundary condition:
The relationship of positive and negative zero-sequence current voltage at failure, whereinFor fault point positive and negative residual voltage over the ground,For
The positive and negative zero-sequence current of fault point), i.e. the relationship of the positive and negative residual voltage electric current of grounding point, obtain collecting route single-phase earthing therefore
Hinder compound sequence network Fig. 7, loop current equation group is obtained by the loop method of analysis；
In formula (3), Ii: the loop current of circuit i；ZS35: 35kV system positive sequence equivalent impedance；ZL35: 35kV line impedance；
ZT40: non-faulting collects line photovoltaic source Equivalent Transformer impedance；ZTm,ZTn1: failure collects line photovoltaic source Equivalent Transformer impedance；
ES: 35kV system phase voltage；Non-faulting collects the equivalent photovoltaic source voltage terminal of line and fault current；Collect
Photovoltaic inversion equivalent source end voltage and fault current between bus and fault point；Fault point is to the light for collecting line end
Lie prostrate inversion equivalent source end voltage and fault current；Z∑0: Zero sequence synthetic impedance；Z∑2: negative phase-sequence comprehensive impedance.
In conjunction with aforementioned Photovoltaic Inverter failure Equivalent Model, collects line fault computation model and contain a system electricity
Source and three photo-voltaic power supplies, each photo-voltaic power supply have the current equation and active reactive equation of oneself, establish photovoltaic and collect line
The non-linear solve system of equation of road singlephase earth fault is as follows:
In formula (4)~(7),Fault point zero-sequence current；ZS35: 35kV system positive sequence equivalent impedance；ZL35: 35kV route
Impedance；ZT40: non-faulting collects line photovoltaic source Equivalent Transformer impedance；ZTm,ZTn1: failure collects the resistance of line photovoltaic source Equivalent Transformer
It is anti-；Zm: the cable positive-negative sequence impedance between collection bus and fault point；ZCf1: the line impedance of failure cable；ES: 35kV system phase
Voltage；
Collect line fault computation model to contain there are three photovoltaic current source, each photovoltaic source have oneself current equation and
Active reactive equation:
Non-faulting collects the equivalent photovoltaic source voltage terminal of line and fault current；η40SFor the equivalent photovoltaic inversion electricity
The capacity coefficient in source, WithEquivalent Photovoltaic Inverter output is active and idle when for failure
Reference value；WithInverter exports active and idle reference value when to operate normally.
Photovoltaic inversion equivalent source end voltage and fault current between collection bus and fault point；ηmSFor this etc.
The capacity coefficient of Photovoltaic Inverter is imitated, WithThe equivalent Photovoltaic Inverter is defeated when for failure
Active and idle reference value out；WithInverter exports active and idle reference value when to operate normally.
Fault point is to the photovoltaic inversion equivalent source end voltage and fault current for collecting line end；ηnSIt is equivalent for this
The capacity coefficient of Photovoltaic Inverter, WithThere is equivalent Photovoltaic Inverter output when for failure
Function and idle reference value；WithInverter exports active and idle reference value when to operate normally.
Formula (4)~(7), share 13 equations and
13 unknown numbers equally acquire convergence solution with Newton-Laphson iteration construction iterated revision equation, realize that photovoltaic collects line
The analysis of road singlephase earth fault.
In order to obtain the photovoltaic electric station grid connection failure protection scheme of perfect Neutral Grounding through Resistance in Electrical, it is necessary to completely grind
Study carefully in the case where neutral resistance Rg takes different resistance values, system line and the different faults position for collecting route occur respectively
Kind symmetrically and the characteristic of unbalanced fault, and must fully consider shown in Fig. 1 protection 1 and protect 2 mutual cooperation relationship.
So system line and the failed shorted phase current and sequence electric current that collect route under different situations need to be calculated separately.Wherein, when event
Barrier occurs when on system line, collects the forward-order current that photo-voltaic power supply generation is flowed only through on route, is free of zero-sequence current.
Calculated result based on example, the 35kV system line and photovoltaic that this representative network can be studied collect route after
Electric protection scheme.
Claims (3)
1. a kind of method for building up of the photovoltaic electric station grid connection line fault computation model of Neutral Grounding through Resistance in Electrical, it is characterised in that
Include the following steps:
(1) based on the inverter failure Equivalent Model with low voltage crossing control strategy, to containing Neutral Grounding through Resistance in Electrical
Photovoltaic electric station grid connection system modeled；The three-phase output voltage of photovoltaic DC-to-AC converter and three-phase export electric current when including failure；
According to the electric current and voltage of the photovoltaic DC-to-AC converter output that instantaneous reactive power theory defines；Three-phase instantaneous active power；Three-phase wink
When reactive power；In Voltage Drop, inverter in order to maintain as far as possible output active reactive power stabilization, inverter output
The active and reactive reference value of current reference value and any photovoltaic DC-to-AC converter；
(2) the photovoltaic electric station grid connection system network architecture of typical Neutral Grounding through Resistance in Electrical is studied, learns grid-connected event
Barrier can be divided into two types, the first failure occurs on system line, and second of failure generation collects line in photovoltaic station
On the road；For the characteristic of these two types of line faults, calculation of fault model is established respectively；
(3) when failure occurs on system line, entire photovoltaic plant can be equivalent to the power supply of a large capacity, power supply
Voltage-controlled current source characteristic is presented, establishes positive and negative zero-sequence network model respectively, the photovoltaic current source for taking positive sequence to control is containing only positive sequence
Component injects positive sequence network, and negative phase-sequence and zero-sequence network do not contain power supply；
(4) when failure generation collects on route in photovoltaic station, entire photovoltaic station cannot be equivalent to a power supply again, it will
Non- failure collects line and failure to collect line difference equivalent；Non- failure collects line and is equivalent to a controlled current source, and failure collects line
It is disconnected from fault point and is equivalent to two power supplys, if fault point is located at cable ZCfOn, then collection bus to failure cable ZCfBetween
Inverter group is equivalent to a controlled current source, ZCfAnother controlled electricity is equivalent to the inverter group collected between line end
Stream source；Whole system equivalence is the network of power supply more than one, establishes positive and negative zero-sequence network model, each photovoltaic current source respectively
Respective positive sequence short circuit current is injected in positive sequence network, negative phase-sequence and zero-sequence network do not contain power supply.
2. a kind of failure analysis methods of the photovoltaic electric station grid connection system of Neutral Grounding through Resistance in Electrical, it is characterised in that: based on power
Benefit requires the line fault computation model of 1 foundation, photo-voltaic power supply is handled as controlled source, in conjunction with the side of various fault types
Boundary's condition obtains fault network nonlinear multivariable equation group, is then asked with Newton-Laphson iteration construction iterated revision equation
Convergence solution is obtained, realizes accident analysis；By taking typical photovoltaic electric station grid connection as an example:
(1) when failure occurs on system line, there is positive and negative zero-sequence network, then series-parallel merging is done into each branch impedance, obtain
To the equivalent network of positive and negative zero sequence；
By taking singlephase earth fault as an example, according to boundary condition, compound sequence network is obtained, obtains loop current equation group；
Simultaneous loop current equation group and Photovoltaic Inverter model equation obtain the solution side of system line singlephase earth fault
Journey group；There are five unknown number and five equations for solve system of equation, can solve, but due to the non-linear relation of equation, it cannot
Analytic solutions directly are acquired, so acquiring convergence solution with Newton-Laphson iteration construction iterated revision equation, realize accident analysis；
(2) when failure generation collects on route in photovoltaic station, there is positive and negative zero-sequence network, then each branch impedance is done in series and parallel
Merge, obtains the equivalent network of positive and negative zero sequence；
By taking singlephase earth fault as an example, combination failure boundary condition obtains compound sequence network, can obtain loop current equation group；
Collect line fault computation model to contain there are three photovoltaic current source, each photovoltaic source has the current equation and active of oneself
These equation groups and loop current equation group simultaneous are obtained the equation that photovoltaic collects line single phase grounding failure by idle equation
Group shares 13 equations and 13 unknown numbers, can solve, and equally constructs iterated revision side with Newton-Laphson iteration
Journey acquires convergence solution, realizes accident analysis.
3. the failure analysis methods of the photovoltaic electric station grid connection system using Neutral Grounding through Resistance in Electrical as claimed in claim 2, point
Various symmetrical and unbalanced fault characteristics occur for analysis route different faults position, it is characterised in that fully consider and collect route guarantor
Matching relationship between shield and system line protection, calculates separately system line and collects the failed shorted phase current and sequence of route
Electric current, so as to the adjusting of relay protection.
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| CN110412377A (en) * | 2019-05-14 | 2019-11-05 | 深圳市禾望电气股份有限公司 | A kind of voltage failure of static reactive generator passes through test method |
| CN110018400B (en) * | 2019-05-20 | 2021-10-01 | 国网甘肃省电力公司天水供电公司 | Direct-current distribution line fault positioning method |
| CN110162889B (en) * | 2019-05-24 | 2022-12-06 | 南方电网科学研究院有限责任公司 | Method for determining fault current of droop control inverter |
| CN111551817A (en) * | 2020-03-31 | 2020-08-18 | 国网江西省电力有限公司电力科学研究院 | Single-phase earth fault current calculation method for resonance earth distribution network |
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