CN105242171B - A kind of transforming plant DC ground connection inspection device for possessing route selection Checking Mechanism - Google Patents
A kind of transforming plant DC ground connection inspection device for possessing route selection Checking Mechanism Download PDFInfo
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- CN105242171B CN105242171B CN201510419061.6A CN201510419061A CN105242171B CN 105242171 B CN105242171 B CN 105242171B CN 201510419061 A CN201510419061 A CN 201510419061A CN 105242171 B CN105242171 B CN 105242171B
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
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- Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
- Y04S10/52—Outage or fault management, e.g. fault detection or location
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Abstract
A kind of transforming plant DC ground connection inspection device for possessing route selection Checking Mechanism, it is related to the device or method of electric fault in detection cable, transmission line or network, more particularly to a kind of inspection device for being used to detect transformer station direct current system earth fault, including on-line monitoring automatic detecting control module and one group of inspection function module；Described inspection function module includes dc bus detection module, and balanced bridge detection module, unbalanced bridge detection module, module is checked in fault branch determination module and route selection；According to the amount of calculation of the quantity of state of the forward and backward Current Voltage of failure and grounding resistance, and the electrical link of three, carry out fault signature identification, using the event driven automatic detecting pattern of logic-based, route selection check function is integrated into the transforming plant DC ground connection inspection device for possessing route selection Checking Mechanism, unbalanced bridge pattern is called to recognize drift and fault branch by logic judgment, it is quick to identify falsely dropping or leaking choosing for DC earthing inspection device.
Description
Technical field
The present invention relates to the device or method of electric fault in detection cable, transmission line or network, more particularly to one kind to be used for
Detect the automatic inspection device of transformer station direct current system earth fault.
Background technology
DC power system is one of three big concealed works in transformer station, important composition of the dc source as power system
Part, uninterruption power source is provided for some important conventional load, relay protection and automatics, telecontrol communication device, and
Emergency lighting power supply is provided.One point earth occurs for DC power system, will not produce short circuit current, system can continue to run with.
However, it is necessary to earth point is searched in time and eliminates earth fault as early as possible, otherwise when another one point earth occurs, it is possible to cause
Recoil simulator, relay protection and automatics, the malfunction of breaker or miss operation, it is possible to cause dc source short-circuit,
Cause fuse blows, or fast independent power source switches off, and equipment is lost operation power, trigger power system catastrophe failure or even
Accident.Therefore, DC power system long-play under Grounding on one point is not allowed, it is necessary to which DC power system is carried out
On-line monitoring, realizes rapid failure diagnosis and state estimation, searches rapidly and exclude earth fault, prevent because of DC power system
Electric power system fault caused by ground connection.The fault line selection method monitored on-line to DC power system, main point
For alternating current method and Direct Current Bridge Method.Alternating current method is also referred to as Low frequency signal injection method, and alternating current method utilizes AC signal and mutual inductor measuring
The ac current signal of amount calculates branch insulation resistance value, it is impossible to positions negative or positive electrode ground connection；In addition, Low frequency signal injection method
It can be falsely dropped because system distribution capacity is excessive, and branch road can be caused harmonic circulating current to be present during looped network mode, be currently used primarily in just
Take formula earth resistance tester.Chinese invention patent " the DC power system earth-fault detecting method of high anti-jamming capacity "
(patent of invention number：ZL201310063104.2 Authorization Notice No.：CN103091606B) disclose a kind of using AC signal note
Enter the detection method of the earth fault of method monitoring DC power system, comprise the following steps：Step 1: at regular intervals,
Between DC power system bus and the earth injected frequency be less than power frequency low-frequency ac electric current signal, Step 2: it is determined that
Measurement obtains current signal on fault branch, is obtained using harmonic extraction unit, and using windowed interpolation method in current signal
The signal of each frequency component, Step 3: comparing the low-frequency ac electric current signal of step 1 injection and the electric current of step 2 acquisition
The signal of each frequency component in signal, it is determined that the place that the low-frequency ac signal respective frequencies component signal of injection disappears,
It is trouble point at this.
Direct Current Bridge Method is not influenceed by distribution capacity, and detection sensitivity is higher, widely used by microcomputer insulation tester.In
A kind of state's application for a patent for invention " DC power system insulated monitoring method and its equipment " (application for a patent for invention number：
201310063104.2 publication number：CN103018614A a kind of DC power system insulated monitoring method and its equipment) are disclosed,
It is time-consuming big for solving the process of Branch-circuit check in the monitoring of DC power system present in prior art, so that can not be timely
The problem of detecting fault branch.The DC power system insulated monitoring method of the embodiment of the present invention includes:It is determined that bus is sent out
During raw failure, it is determined that the pole to be detected for the branch road being connected with the bus to break down；Wherein, it is connected with the pole to be detected of branch road
The insulating resistance value of bus is not more than first threshold；The pole to be detected of branch road is detected.The embodiment of the present invention is sent out in bus
During raw failure, by the pole to be detected for the branch road for determining to be connected with the bus to break down, and the pole to be detected of the branch road is entered
Row detection avoids to determine fault branch and in bus-bar fault, is both needed to all patrol the positive pole and negative pole of each branch road every time
Inspection, so as to substantially reduce the time of detection fault branch.
But the route selection that above-mentioned technical proposal is not directed to transforming plant DC ground connection inspection is checked, and is lacked exhausted to multiple branch circuit
Edge declines the check of information, can not exclusive PCR information, may falsely drop or leak choosing during differentiation.
The content of the invention
It is an object of the invention to provide a kind of transforming plant DC for possessing route selection Checking Mechanism to be grounded inspection device, fully profit
The advantages of with balanced bridge pattern and unbalanced bridge mode computation grounding resistance, according to the state of the forward and backward Current Voltage of failure
The amount of calculation of amount and grounding resistance, and the electrical link of three, carry out fault signature identification, identification drift branch road and ground connection branch
Road, grounding resistance calculating process is checked using reduction to absurdity, overcome earth fault to falsely drop, leak select while, improve therefore
Hinder the lookup speed of branch road.
Technical scheme is used by the present invention solves above-mentioned technical problem：
A kind of transforming plant DC ground connection inspection device for possessing route selection Checking Mechanism, for transforming plant DC power-supply system pair
Ground insulated on-line monitoring, including on-line monitoring automatic detecting control module and one group of inspection function module；It is characterized in that：
Described inspection function module includes dc bus detection module, balanced bridge detection module, unbalanced bridge inspection
Module is surveyed, module is checked in fault branch determination module and route selection；
Described on-line monitoring automatic detecting control module is connected to described inspection function module, by controlling inspection work(
The operation of energy module, performs the event driven automatic detecting pattern of logic-based；
Described dc bus detection module uses unbalanced bridge pattern, and positive and negative dc bus is calculated over the ground by detecting
Insulaion resistance, the earth fault of positive bus-bar or negative busbar is monitored on-line；
Described balanced bridge detection module uses balanced bridge pattern, calculates branch insulation resistance by detecting, searches
DC ground fault branch road；
Described unbalanced bridge detection module uses unbalanced bridge pattern, and it is positive and negative to test resistor bridge change by switching
Dc bus voltage-to-ground and the total leakage current of branch road, detection calculate each branch insulation resistance, search DC ground fault branch road；
Described fault branch determination module, for the insulaion resistance testing result of more each branch road, select determination
The fault branch of earth fault；
Module is checked in described route selection, for carrying out event according to the correlation logic of the voltage before and after failure, electric current and resistance
Hinder feature identification, avoid falsely dropping or leaking choosing for fault branch；
The event driven automatic detecting pattern of described logic-based comprises the following steps：
S100：Busbar grounding resistance is calculated using unbalanced bridge mode detection；
S200：Grounding inspection is carried out using balanced bridge pattern；
S220：Judge whether leakage current changes, if leakage current is unchanged, judge that the branch road has drift fault-free；It is no
Then, order performs step S240；
S240：Judge whether leakage current is monotonically changed, if leakage current is not to be monotonically changed, start unbalanced bridge mould
Formula；Otherwise, order performs step S260；
S260：Electric current subtracts PRE-FAULT CURRENT after failure, then calculates grounding resistance, judges whether to meet that branch trouble is sentenced
According to if meeting branch trouble criterion, judging the branch road for fault branch；Otherwise, unbalanced bridge pattern is started.
A kind of preferable technical scheme of the transforming plant DC for the possessing route selection Checking Mechanism ground connection inspection device of the present invention,
It is characterized in that module is checked in described route selection also includes reduction to absurdity check submodule, described reduction to absurdity checks submodule connection
To dc bus detection module, according to the busbar grounding resistance tried to achieve during DC earthing inspection route selection, reversely calculate positive and negative
The estimated value of busbar voltage；If any one of the estimated value is different from the measured value of corresponding voltage, infer that route selection result has
By mistake.
A kind of superior technique scheme of the route selection check method of the transforming plant DC ground connection inspection of the present invention, its feature exist
Submodule is checked in described reduction to absurdity and is also connected to fault branch determination module, according to being asked during DC earthing inspection route selection
Each branch road positive and negative bus resistance to earth, calculate negative busbar all-in resistance and positive bus-bar all-in resistance over the ground over the ground, reversely calculate
The estimated value of positive and negative busbar voltage；If any one of the estimated value is different from the measured value of corresponding voltage, route selection knot is inferred
Fruit is wrong.
The beneficial effects of the invention are as follows：
The route selection check method of the transforming plant DC ground connection inspection of the present invention, according to the state of the forward and backward Current Voltage of failure
The amount of calculation of amount and grounding resistance, and the electrical link of three, fault signature identification is carried out, using logic-based event-driven
Automatic detecting pattern, can effectively take into account the rapidity of balanced bridge and the fault-tolerance of unbalanced bridge, improve and search speed
And fault tolerance level, realize quick diagnosis and fix a breakdown, both improved the operating efficiency of engineering site, reduce again and blindly draw road
Caused risk.
The transforming plant DC of the present invention is grounded the practical of the route selection check method of inspection, only route selection need to be checked into function
It is integrated into the transforming plant DC ground connection inspection device for possessing route selection Checking Mechanism, passes through the uneven electricity of logic judgment dynamic call
Bridge mode recognizes drift and fault branch, and the automatic detecting pattern of unbalanced bridge pattern is called relative to existing timing,
Falsely dropping or leaking choosing for DC earthing inspection device can be quickly identified, inspection device is improved on the premise of hardware cost is not increased
Performance.
Brief description of the drawings
Fig. 1 is the unbalanced bridge mode detection schematic diagram of busbar grounding resistance；
Fig. 2 is the bus insulation resistance measuring circuit figure of K1 closure states；
Fig. 3 is the bus insulation resistance measuring circuit figure of K2 closure states；
Fig. 4 is DC detection method branch road detection principle diagram；
Fig. 5 is the single spur track ground connection equivalent circuit diagram based on balanced bridge pattern；
Fig. 6 is the single spur track ground connection equivalent circuit diagram based on unbalanced bridge pattern；
Fig. 7 is the control flow chart of the event driven automatic detecting pattern of logic-based；
Fig. 8 is the equivalent circuit diagram of multiple branch circuit ground connection；
Fig. 9 is the structural representation of transforming plant DC power-supply system insulation against ground on-Line Monitor Device.
Embodiment
For better understanding of the above-mentioned technical proposal of the present invention, carry out with reference to the accompanying drawings and examples further
It is described in detail.
The transforming plant DC for the possessing route selection Checking Mechanism ground connection inspection device of the present invention, for transforming plant DC power supply system
Insulation against ground of uniting is monitored on-line, and described transforming plant DC power-supply system includes positive bus-bar+KM and negative busbar-KM, and connection
Some direct current branch of conventional load, relay protection and automatics, telecontrol communication device and devices for emergency illumination；Such as Fig. 1 institutes
Show, described transforming plant DC power-supply system also includes one group of direct-current bridge element for system on-line monitoring, and described is straight
Flowing bridge element includes balance resistor bridge Rb1, Rb2 that two resistance identical measuring resistances are formed；Two resistance identical marks
Test resistor bridge RL1, RL2 that quasi- resistance is formed；The relay switching switch K1 of two control test resistor bridge on-states,
K2；And the on-Line Monitor Device 1 of inspection is carried out for the insulation against ground state to transforming plant DC power-supply system, i.e. inspection fills
Put, referring to Fig. 4.
The present invention possess route selection Checking Mechanism transforming plant DC ground connection inspection device 1 structure as shown in figure 9, including
Monitor automatic detecting control module 10 and one group of inspection function module on-line；Described inspection function module is examined including dc bus
Module 11 is surveyed, balanced bridge detection module 12, unbalanced bridge detection module 13, fault branch determination module 14 and route selection are checked
Module 15；
Described on-line monitoring automatic detecting control module 10 is connected to described each inspection function module, each by controlling
The operation of inspection function module, perform the event driven automatic detecting pattern of logic-based；
Described dc bus detection module 11 uses unbalanced bridge pattern, and positive and negative dc bus pair is calculated by detecting
Ground insulaion resistance, the earth fault of positive bus-bar or negative busbar is monitored on-line；
Described balanced bridge detection module 12 uses balanced bridge pattern, calculates branch insulation resistance by detecting, looks into
Look for DC ground fault branch road；
Described unbalanced bridge detection module 13 uses unbalanced bridge pattern, and testing resistor bridge by switching changes just
Negative dc bus voltage-to-ground and the total leakage current of branch road, detection calculate each branch insulation resistance, search DC ground fault branch road；
Described fault branch determination module 14, for the insulaion resistance testing result of more each branch road, selection determines hair
The fault branch of raw earth fault；
Module 15 is checked in described route selection, for being carried out according to the correlation logic of the voltage before and after failure, electric current and resistance
Fault signature recognizes, and avoids falsely dropping or leaking choosing for fault branch.
Busbar grounding resistance detection principle uses bridge method, and its principle is as shown in Figure 1.Wherein Up、UnFor positive bus-bar and negative mother
Line voltage；Rb1、Rb2To balance resistor bridge, they are resistance identical measuring resistances, are separately fixed at dc bus both ends；RL1、
RL2To test resistor bridge, they are resistance identical measuring resistances, by relay switching to dc bus；Balance resistor bridge
Selection with test resistor bridge numerical value will consider the power of bus bar resistance and the maximum detectability of electricity leakage sensor.Rx、RyTo treat
Survey grounding resistance；Geodetic point voltage is zero potential in figure, meets formula：
Un/Rb1+Up/Rb2+Un/RL1+Up/RL2+Un/Rx+Up/Ry=0；
Turning on and off for K1, K2 is switched by switching during measurement, so as to be calculated according to obtained Un and Up is measured
Dc bus insulation against ground resistance.
Equivalent circuit is as shown in Figure 2 when K1 is closed.It can be obtained according to Fig. 2：
Un1/Rb1+Up1/Rb2+Un1/RL1+Un1/Rx+Up1/Ry=0 (1)
Equivalent circuit is as shown in Figure 3 when K2 is closed.From circuit formulation：
Un2/Rb1+Up2/Rb2+Up2/RL2+Un2/Rx+Up2/Ry=0 (2)
Combine to obtain Rx and Ry by formula 1,2
Rx=(Un1*Up2-Un2*Up1)/(A*Up2-B*Up1) (3)
Ry=(Un2*Up1-Un1*Up2)/(A*Un2-B*Un1) (4)
Wherein：A=- (Un1/Rb1+Up1/Rb2+Un1/RL1), B=- (Un2/Rb1+Up2/Rb2+Up2/RL2)。
It was found from above formula, R is influenceedxAnd RyFactor be measurement voltage Un1, Un2, Up1, Up2With fixed resistance Rb1、Rb2、RL1、
RL2.As long as so consider influence of the measurement voltage to grounding resistance.Because DC voltage value is larger, less absolute value
Measured deviation will not cause larger relative quantity to change, and it is higher that it measures confidence level opposite branches.
Direct Current Bridge Method utilizes bus positive pole+KM voltage-to-grounds, bus negative pole-KM voltage-to-grounds and branch road DC leakage current
Branch road both positive and negative polarity insulation against ground grounding resistance is calculated, route selection is carried out in conjunction with branch insulation alarm setting valve.
Direct current branch Cleaning Principle is as shown in figure 4, wherein I1, I2 correspond to 1# branch roads and the total leakage current of 2# branch roads.
Bridge balance measurement method：
During DC balance electric bridge mode computation branch insulation resistance, the direction of the total leakage current of branch road, positioning branch are first determined whether
Road negative or positive electrode insulation reduces, and then calculates grounding resistance with positive pole line-to-earth voltage or negative busbar voltage-to-ground.With reference to
Fig. 1 and Fig. 4 can show that single spur track is grounded the equivalent circuit based on balanced bridge pattern as shown in figure 5, wherein I0Always leaked for branch road
Electric current, direction shown in figure are reference direction.Positive and negative busbar resistance to earth value can be tried to achieve according to Fig. 5：
I0It is negative：Positive bus-bar resistance to earth value is infinity,
Negative busbar resistance to earth value Rn=Un/I0(5),
I0For just：Positive bus-bar resistance to earth value Rp=Up/I0(6),
Negative busbar resistance to earth value is infinity.
Unbalanced bridge mensuration：
During direct current unbalanced bridge mode computation branch insulation resistance, equally using positive pole line-to-earth voltage, negative busbar pair
The total leakage current measurement of ground voltage, branch road direct current calculates, but needs to test resistor bridge change positive pole line-to-earth voltage by switching, bears
Bus Voltage and the total leakage current of branch road.
Close K2 (input RL2) when, branch road equivalent circuit such as Fig. 6 (a) is shown, now Up、Un、I0Value U respectivelyp1、Un1、
I1.Close K1 (input RL1) when, branch road equivalent circuit such as Fig. 6 (b) is shown, now Up、Un、I0Value U respectivelyp2、Un2、I2.Electric current
Outflow node A is positive direction, RyAnd RxRespectively the positive bus-bar insulation against ground resistance value of certain branch road and negative busbar insulation against ground resistance
Value.
It can be obtained according to Fig. 6 (a)：
I1-Un1/Rx-Up1/Ry=0 (7)
It can be obtained according to Fig. 6 (b)：
I2-Un2/Rx-Up2/Ry=0 (8)
Association type (7) and formula (8) solve：
Rx=(Up1Un2-Up2Un1)/(Up1I2-Up2I1) (9)
Ry=(Up2Un1-Up1Un2)/(Un1I2-Un2I1) (10)
If RyFor infinity, i.e. negative busbar monopole insulation against ground reduces, and passes through (7) and (8) simplified formula formula：
Rx=(Un2-Un1)/(I2-I1) (11)
If RxFor infinity, i.e. positive bus-bar monopole insulation against ground reduces, and passes through (7) and (8) simplified formula formula：
Ry=(Up2-Up1)/(I2-I1) (12)
When certain pole is grounded, reporting an other pole by mistake according to formula 11 and 12, there is also identical grounding resistance.
DC leakage flow sensor (transformer) is non-contact sensor, senses by magnetic induction loop and tests, measurement object
Signal is small, easily by extraneous interference (such as geomagnetic noise, transformer place difference, and null offset is also different)；DC leakage current
Sensor magnetic coil remanent magnetism；The drift (temperature drift, when drift etc.) of DC leakage current sensor detection circuit such as amplifier etc. is direct current,
After long-play, current sensor is set drift to be present, so calculating branch insulation grounding resistance according to formula 9 and 10
Value, easily produce wrong report branch road.Route selection wrong report or the state failed to report are analyzed by the following examples, describe the change of the present invention in detail
Electric station DC is grounded the route selection check method of inspection：
(1) influence of the DC leakage current sensor fluctating to calculating grounding resistance.If Fig. 4 is in actual 220V systems
When, do not measure U under switching test resistor bridgep、UnRespectively 176V, -44V, it is as follows that balancing method calculates grounding resistance：
1# branch road drifts I10=2mA；Ry1=176/2=88K Ω
1# branch road drifts I10=-2mA；Rx1=-44/ (- 2)=22K Ω
2# branch road drifts I20=-2mA, i.e., actual measurement is -6.4mA, Rx2=6.875K Ω
Unbalanced bridge pattern eliminates drift by difference component to be influenceed.
(2) the magnetic coil remanent magnetism in DC leakage flow sensor, signal interference, sample circuit are unstable there is measurement electric current
Saltus step.Such as certain branch road DC leakage flow sensor detection actual DC leakage current is run down in certain power station all the year round 0.5mA value
Saltus step, while branch insulation resistance is also not reaching to alarming value.220V systems (branch insulation is alarmed as 50K Ω) are set to Fig. 4
Exemplified by be analyzed as follows：
The negative busbar insulation against ground of 1# branch roads is reduced to 60K, now Up、UnRespectively 180V, -40V, I1May be-
0.667mA、-1.167mA；I.e. negative busbar insulation against ground resistance value corresponds to 60K Ω and 34K Ω, and 2# branch roads negative busbar is over the ground
There is a 10K Ω resistance, directly alarm, may take the insulation of 1# branch roads out of simultaneously reduces.
Identical condition, is calculated using unbalanced bridge, due to the sampled value saltus step of 1# branch road DC leakage flow sensors
And falsely drop, select 1# branch roads more.
Two point analysis more than, the drift of DC leakage current sensor sample can solve by unbalanced bridge pattern,
But for common DC leakage current sensor sample saltus step, even unbalanced bridge pattern can not also solve.In addition, balance
Electric bridge pattern can't detect positive and negative busbar insulating resistance while situation about declining, that is, operating dead zone be present.
The signature analysis of fault branch：
Dc bus grounding resistance calculates precision and is higher than branch road, and its priority is highest.
When route selection is carried out after calculating ground fault, the absolute value of grounding resistance is not only considered, it is also contemplated that before and after failure
The relative variation of the quantity of states such as Current Voltage --- voltage x current change direction and change size meet true ground connection.That is basis
The consecutive variations of voltage swing and leakage current size, the correlation logic of analysis resistance and voltage, electric current are checked.Pass through circuit
Derive, following feature can be drawn：
(1) when certain branch road has drift electric current or sample rate current saltus step, i.e., drift electric current is leakage current before failure, therefore
Leakage current is constant before and after barrier, its grounding resistance and the linear change of voltage, grounding resistance may be caused to become because voltage reduces
It is small and meet grounding resistance threshold value, but it is fault branch that should exclude the branch road.
(2) insulate relatively low branch road, smaller leakage current be present, and during other groundings, voltage reduces, but this corresponding branch
Road electric current also reduces, and will not falsely drop.
(3) when there is earth fault in the branch road of no drift, leakage current increase, voltage-to-ground reduce, grounding resistance with
Voltage and accelerate change.
(4) when certain branch road has leakage current, leakage current monotonic increase before and after failure, then it is that homopolarity is exhausted that failure is front and rear
Edge declines, but there is a possibility that to falsely drop.
(5) when certain branch road has leakage current, leakage current is non-monotonic incremental before and after failure, then needs before analyzing failure
Analyze whether leakage current is drift in the presence of the grounding resistance situation of change of one pole of electric leakage after a failure.If not drift,
It is then that another pole of the branch road is grounded.If drift, then need to make the difference stream, avoid Lou selecting.
(6) it is to distinguish under current time identification in the case of positive and negative busbar insulating resistance declines simultaneously
The sequencing of the two poles of the earth ground connection.Its individual features in the balanced mode is first to report a certain pole to be grounded, and then and does not report failure
Ground connection.Grounding resistance now is searched with regard to needing to switch under uneven pattern, avoids Lou selecting.
Under normal circumstances, be cannot be distinguished by (1) and (2) small leakage current be because drift or because insulation reduction lead
Cause.So there can not be leakage current according to branch road to judge that drift occurs for the branch road.
Analyzed more than, the present invention according to the quantity of state of the forward and backward Current Voltage of failure and the amount of calculation of grounding resistance, with
And the electrical link of three, carry out fault signature identification, it is proposed that the event driven automatic detecting pattern of logic-based.The present invention
Possess route selection Checking Mechanism transforming plant DC ground connection inspection device route selection check method flow one embodiment such as Fig. 7
It is shown, comprise the following steps：
S100：Busbar grounding resistance is calculated using unbalanced bridge mode detection；
S200：Grounding inspection is carried out using balanced bridge pattern；
S220：Judge whether leakage current changes, if leakage current is unchanged, judge that the branch road has drift fault-free；It is no
Then, order performs step S240；
S240：Judge whether leakage current is monotonically changed, if leakage current is not to be monotonically changed, start unbalanced bridge mould
Formula；Otherwise, order performs step S260；
S260：Electric current subtracts PRE-FAULT CURRENT after failure, then calculates grounding resistance, judges whether to meet that branch trouble is sentenced
According to if meeting branch trouble criterion, judging the branch road for fault branch；Otherwise, unbalanced bridge pattern is started.
Checked based on reduction to absurdity：
Mathematically analyzed and understood according to the fault-tolerant ability of bridge method：
1) balanced bridge pattern is unknown according to 1 equation (5) or formula (6), solution 1 equivalent to 2 variables known to root
Amount.When as long as 2 known quantities have 1 error, then solving result mistake, according to it is single when discontinuity surface data can not be fault-tolerant.
2) unbalanced bridge pattern, according to 2 equations (7) and formula (8), solves 2 not equivalent to known 6 known quantities
The amount of knowing.When wherein 1 unknown quantity is infinitely great (when monopole is grounded), equivalent to reducing 1 unknown quantity；If now occur zero
Drift, equivalent to 1 new unknown quantity of increase, now become to solve 2 unknown quantitys again, still there is solution.If but there are the two poles of the earth and connect
Ground, while when having drift again, 3 unknown quantitys of equivalent to 2 equation solutions, unbalanced bridge pattern is without solution.
It is described according to one embodiment of the transforming plant DC for the possessing route selection Checking Mechanism ground connection inspection device of the present invention
Route selection check module 15 also include reduction to absurdity check submodule, described reduction to absurdity check submodule be connected to dc bus inspection
Module 11 is surveyed, according to the busbar grounding resistance tried to achieve during DC earthing inspection route selection, reversely calculates positive and negative busbar voltage
Estimated value；According to the estimated value and the difference of the measured value of corresponding voltage, infer that route selection result is wrong.Described reduction to absurdity school
Nucleon module performs the step of following reduction to absurdity is checked：
S270：According to the busbar grounding resistance R tried to achieve during DC earthing inspection route selectionxAnd Ry, reversely calculate positive and negative
The estimated value U' of busbar voltagepAnd U'n；
S272：The positive and negative busbar voltage estimated value U' of gained will be calculatedpAnd U'n, with corresponding positive and negative busbar voltage measured value
UpAnd UnIt is compared, if U'pAnd U'nAny one of be different from its measured value, then judge the branch road tried to achieve during route selection
The middle special circumstances that bridge method be present and can not accurately calculate, described on-Line Monitor Device send the wrong warning letter of route selection result
Breath.
One preferred embodiment of inspection device is grounded according to the transforming plant DC for possessing route selection Checking Mechanism of the present invention,
Described reduction to absurdity checks submodule and is also connected to fault branch determination module 14, according to being asked during DC earthing inspection route selection
The positive and negative bus resistance to earth of each branch road obtained, negative busbar and positive bus-bar all-in resistance over the ground are calculated, reversely calculates positive and negative bus
The estimated value of voltage；According to the estimated value and the difference of the measured value of corresponding voltage, infer that route selection result is wrong.Described
It is further comprising the steps of after step S272：
S274：According to the branch road i tried to achieve during route selection positive and negative bus resistance to earth RyiAnd Rxi, calculate negative busbar pair
Ground all-in resistance RxΣ=Rx1//Rx2....Rxm//Rb1, positive bus-bar all-in resistance R over the groundyΣ=Ry1//Ry2....Rym//Rb2, wherein, i
For the integer from 1 to m, m is the total circuitry number of transforming plant DC power-supply system；
S276：According to negative busbar all-in resistance R over the groundxΣWith positive bus-bar all-in resistance R over the groundyΣ, reversely calculate positive and negative bus electricity
The estimated value U " of pressurepAnd Un"：
U"p=U*RyΣ/(RxΣ+RyΣ) (13)
Un"=- U*RxΣ/(RxΣ+RyΣ) (14)
Wherein, U "pFor the estimated value of positive pole line voltage, Un" it is the estimated value of negative busbar voltage, U is DC bus-bar voltage,
RxΣFor negative busbar all-in resistance over the ground, RyΣFor positive bus-bar all-in resistance over the ground；
S278：The positive and negative busbar voltage estimated value U " of gained will be calculatedpAnd Un", with corresponding positive and negative busbar voltage measured value
UpAnd UnIt is compared, if U "pAnd Un" any one of be different from its measured value, then judge the m bars tried to achieve during route selection
In branch road, the special circumstances that bridge method can not be calculated accurately all the way at least be present, described on-Line Monitor Device sends route selection
As a result wrong information warning.
The principle checked using reduction to absurdity, it is first assumed that all grounding resistance calculations values are true, then by counting
The grounding resistance calculated calculates the estimated value U' for the positive and negative busbar voltage for participating in more ground branchp、U'n、U"pAnd Un".If calculate
Go out value U'p、U'n、U"pAnd Un" with measured value UpAnd UnDifference, then illustrate that bridge method fails correctly to handle drift electric current.From formula
(13) understood with formula (14), the earth resistance meter of any one branch road in m branch road calculates mistake, will all cause the bus of calculating
Voltage from survey busbar voltage it is different, so as to illustrate to exist in these branch roads balanced bridge pattern or unbalanced bridge pattern without
The special circumstances that method accurately calculates to route selection result using other method, it is necessary to further carry out manual intervention.
Embodiment effect analysis
Build up within 2006 operating direct current 220V system monitorings to Shanghai transformer station to analyze, virtual voltage 243.5V,
Using the microcomputer insulating monitor WJY3000A of Shenzhen special fast power equipment difficult to understand, DC power system separates 48 tunnels and feeds out loop.
Select 4 road branch roads to be analyzed, selection branch road is respectively：
1# branch road direct current sampling circuits are normal, and no drift, sampled result stability is good, good insulating；
4# branch road direct current sampling circuits are normal, and no drift, sampled result stability is good, and negative busbar insulating resistance value reduces；
17# roads direct current sampling circuit is normal, there is drift, and sampled result stability is good, and negative busbar insulating resistance value reduces；
33# roads direct current sampling circuit is normal, and no drift, sampled result stability saltus step is big, negative busbar insulating resistance value drop
It is low.
Using route selection Checking Mechanism, data record is carried out to fielded system as shown in table 1 to table 3, table 4 and table 5 are regular inspection
Experimental data, wherein, table 4 is the experimental data that 1# branch roads negative busbar connects 10K ohmic loads over the ground, and table 5 is 1# branch road negative busbars
The experimental data being directly grounded.In 1~table of table 5：RBpAnd RBnRespectively balance bridge method calculate just over the ground with negative resistance to earth
Value, RNpAnd RNnRespectively uneven bridge method calculate just over the ground with negative resistance to earth value, unit K Ω.
Table day entry data in 1 2014 year June 10
Table day entry data in 2 2014 year July 11
3 2014 years day entry data of August 10 of table
4 2014 years day entry data of September 10 of table (regular inspection experiment 1# is negative to meet 10K)
5 2014 years day entry data of September 10 of table (regular inspection experiment 1# negative busbars are directly grounded experiment)
By the analysis of experimental data of 1~table of table 5, the data route selection of table 4 is 1# and 33#, because 33# direct current transducer samples
It is unstable to cause multiselect；Table 5 and the same result of table 4.
Using the data of 1~table of route selection Checking Mechanism combination table 5, because insulation drop be present in 4#, 17#, 33# branch road
It is low, using mathematical statistics Algorithm Analysis variation tendency, rate of change it is big for preferential prompt message.So prompt 1# branch roads to table 4
For the branch road preferentially investigated；And same analytical table 5,1# branch roads are also the branch road preferentially investigated.And the route selection check side of the present invention
Method can be analyzed to the data analysis and logical derivation before and after failure and find out the big direct current transducer 17# of CT drifts.Based on the present invention
Route selection check method to the data analysis and derivation after failure, 33# branch roads can be picked out and sampling saltus step be present.Check and complete
Afterwards, form corresponding check to report, inform that operation maintenance personnel 17# has drift, 33# has sampling saltus step.
Those of ordinary skill in the art is it should be appreciated that the embodiment of the above is intended merely to the explanation present invention's
Technical scheme, and be not used as limitation of the invention, any connotation based on the present invention is to embodiment described above
Change, the modification made, it will all fall in the scope of the claims of the present invention.
Claims (3)
1. a kind of transforming plant DC ground connection inspection device for possessing route selection Checking Mechanism, for transforming plant DC power-supply system over the ground
Insulated on-line monitoring, including on-line monitoring automatic detecting control module and one group of inspection function module；It is characterized in that：
Described inspection function module includes dc bus detection module, balanced bridge detection module, unbalanced bridge detection mould
Module is checked in block, fault branch determination module and route selection；
Described on-line monitoring automatic detecting control module is connected to described inspection function module, by controlling inspection function mould
The operation of block, perform the event driven automatic detecting pattern of logic-based；
Described dc bus detection module uses unbalanced bridge pattern, and positive and negative dc bus insulation against ground is calculated by detecting
Resistance, the earth fault of positive bus-bar or negative busbar is monitored on-line；
Described balanced bridge detection module uses balanced bridge pattern, calculates branch insulation resistance by detecting, searches direct current
Earth fault branch road；
Described unbalanced bridge detection module uses unbalanced bridge pattern, and testing resistor bridge by switching changes positive and negative direct current
Bus Voltage and the total leakage current of branch road, detection calculate each branch insulation resistance, search DC ground fault branch road；
Described fault branch determination module, for the insulaion resistance testing result of more each branch road, selection determines to be grounded
The fault branch of failure；
Module is checked in described route selection, special for carrying out failure according to the correlation logic of the voltage before and after failure, electric current and resistance
Sign identification, avoids falsely dropping or leaking choosing for fault branch；
The event driven automatic detecting pattern of described logic-based comprises the following steps：
S100：Busbar grounding resistance is calculated using unbalanced bridge mode detection；
S200：Grounding inspection is carried out using balanced bridge pattern；
S220：Judge whether leakage current changes, if leakage current is unchanged, judge that the branch road has drift fault-free；Otherwise, it is suitable
Sequence performs step S240；
S240：Judge whether leakage current is monotonically changed, if leakage current is not to be monotonically changed, start unbalanced bridge pattern；
Otherwise, order performs step S260；
S260：Electric current subtracts PRE-FAULT CURRENT after failure, then calculates grounding resistance, judges whether to meet branch trouble criterion, if
Meet branch trouble criterion, judge the branch road for fault branch；Otherwise, unbalanced bridge pattern is started.
2. the transforming plant DC ground connection inspection device according to claim 1 for possessing route selection Checking Mechanism, it is characterised in that
Module is checked in described route selection also includes reduction to absurdity check submodule, and described reduction to absurdity checks submodule and is connected to dc bus
Detection module, according to the busbar grounding resistance tried to achieve during DC earthing inspection route selection, reversely calculate positive and negative busbar voltage
Estimated value；If any one of the estimated value is different from the measured value of corresponding voltage, infer that route selection result is wrong.
3. the transforming plant DC ground connection inspection device according to claim 2 for possessing route selection Checking Mechanism, it is characterised in that
Described reduction to absurdity checks submodule and is also connected to fault branch determination module, according to being tried to achieve during DC earthing inspection route selection
Each branch road positive and negative bus resistance to earth, calculate negative busbar all-in resistance and positive bus-bar all-in resistance over the ground over the ground, reversely calculate
The estimated value of positive and negative busbar voltage；If any one of the estimated value is different from the measured value of corresponding voltage, route selection knot is inferred
Fruit is wrong.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109782106A (en) * | 2019-01-07 | 2019-05-21 | 邯郸钢铁集团有限责任公司 | A kind of DC system earth fault lookup device and method |
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| CN109444631B (en) * | 2018-11-12 | 2020-12-25 | 中车永济电机有限公司 | Method for judging main circuit grounding of traction converter of alternating-current, direct-current and alternating-current electric locomotive |
| CN110212497A (en) * | 2019-03-28 | 2019-09-06 | 国网辽宁省电力有限公司电力科学研究院 | Based on the substation of fault location DC power supply active protective device and guard method |
| CN110514945A (en) * | 2019-07-12 | 2019-11-29 | 国网浙江省电力有限公司嘉兴供电公司 | A kind of multifunctional DC grounding test apparatus and Method for Measuring Insulating Resistance |
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