CN105182148B - A kind of transforming plant DC power-supply system - Google Patents
A kind of transforming plant DC power-supply system Download PDFInfo
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- CN105182148B CN105182148B CN201510419366.7A CN201510419366A CN105182148B CN 105182148 B CN105182148 B CN 105182148B CN 201510419366 A CN201510419366 A CN 201510419366A CN 105182148 B CN105182148 B CN 105182148B
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Abstract
The present invention relates to a kind of transforming plant DC power-supply system; it is related to relay protection and automatics, the DC power system of telecontrol communication device power supply and its protection of transformer station; specifically a kind of transforming plant DC power-supply system for possessing earth fault automatic inspection function; including inspection control module, module is checked in the dc bus detection module being connected with the inspection control module output end, direct current branch detection 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 power-supply system for possessing ground connection inspection 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 relay protection for transformer station and automatics, the DC power system of telecontrol communication device power supply
And its protection, and in particular to a kind of transforming plant DC power-supply system, it is particularly a kind of to possess earth fault automatic inspection function
Transforming plant DC power-supply system.
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 transformer dc source system, described DC power system is according to failure
The quantity of state of forward and backward Current Voltage and the amount of calculation of grounding resistance, and the electrical link of three, fault signature identification is carried out,
Identify drift branch road and ground branch, overcome earth fault to falsely drop, leak select while, improve the lookup speed of fault branch.
To achieve the above object, the solution of the present invention is：A kind of transformer dc source system, described transforming plant DC
Power-supply system includes positive bus-bar and negative busbar, for connect conventional load, relay protection and automatics, telecontrol communication device and
Some direct current branch of devices for emergency illumination, for one group of direct-current bridge element of system on-line monitoring, and for becoming
The insulation against ground state of electric station DC power-supply system carries out the on-Line Monitor Device of inspection, and each direct current branch is provided with direct current leakage
Current sensor；
The voltage detecting input of described on-Line Monitor Device, connect the positive bus-bar of transforming plant DC power-supply system and bear
Bus, the branch road leakage current test input of described on-Line Monitor Device, the DC leakage current of each direct current branch of connection
Sensor, the leakage current of each direct current branch is sampled；
Described on-Line Monitor Device includes inspection control module, and be connected with the inspection control module output end
Module is checked in dc bus detection module, direct current branch detection module and route selection, and described inspection control module is used to control directly
The operation that module is checked in bus detection module, direct current branch detection module and route selection is flowed, described dc bus detection module is used
In the direct-current bridge element by switching DC power system, detection calculates the insulation against ground resistance of positive and negative dc bus, aligned
The earth fault of bus or negative busbar is monitored on-line, and described direct current branch detection module, which is used to detect, calculates each direct current branch
The insulaion resistance on road, and the insulaion resistance testing result of more each branch road, selection determine that the fault branch of earth fault occurs；Institute
The route selection stated checks module and is used to carry out fault signature identification according to the correlation logic of the voltage before and after failure, electric current and resistance,
Avoid falsely dropping or leaking choosing for fault branch.
According to transforming plant DC power-supply system of the present invention, described direct-current bridge element includes two balance bridge electricity
The relay switching switch of resistance, two test resistor bridges, and two controls test resistor bridge on-state, described two
Individual balance resistor bridge is separately fixed at dc bus both ends, and described test resistor bridge switches switch on-off to directly by relay
Flow on bus.
According to transforming plant DC power-supply system of the present invention, busbar grounding resistance detection uses bridge method, geodetic point
Voltage is zero potential, meets formula：
Un/Rb1+Up/Rb2+Un/RL1+Up/RL2+Un/Rx+Up/Ry=0
Wherein Up、UnFor positive bus-bar and negative busbar voltage；Rb1、Rb2To balance resistor bridge, they are resistance identical standards
Resistance；RL1、RL2To test resistor bridge, they are resistance identical measuring resistances；Balance resistor bridge and test resistor bridge numerical value
Choose the maximum detectability of the power and electricity leakage sensor that to consider bus bar resistance；Rx、RyFor grounding resistance to be measured.
According to transforming plant DC power-supply system of the present invention, pass through relay when being measured to busbar grounding resistance
Switching switch turns on and off, the U obtained according to measurementp、UnCalculate the insulation against ground resistance R of dc busx、Ry, i.e.,：
Two relay switchings switch each self-closing, respectively obtain：
Un1/Rb1+Up1/Rb2+Un1/RL1+Un1/Rx+Up1/Ry=0
Un2/Rb1+Up2/Rb2+Up2/RL2+Un2/Rx+Up2/Ry=0
So as to which R be calculatedx、RyValue.
According to transforming plant DC power-supply system of the present invention, described direct current branch detection module includes balanced bridge
Detection unit, unbalanced bridge detection unit and fault branch identifying unit, described balanced bridge detection unit is using balance
Electric bridge pattern, branch insulation resistance is calculated by detecting, searches DC ground fault branch road；Described unbalanced bridge detection is single
Member uses unbalanced bridge pattern, tests the positive and negative dc bus voltage-to-ground of resistor bridge change by switching and branch road always leaks electricity
Stream, detection calculate each branch insulation resistance, search DC ground fault branch road；Described fault branch identifying unit, for than
The insulaion resistance testing result of more each branch road, selection determine that the fault branch of earth fault occurs.
According to transforming plant DC power-supply system of the present invention, described balanced bridge mode detection grounding resistance
When, the direction of the total leakage current of direct current branch is first determined whether, the insulation of positioning DC branch road negative or positive electrode reduces, then according to positive pole
Line-to-earth voltage or negative busbar voltage-to-ground, grounding resistance is calculated, be specially：
If judge the total leakage current I of direct current branch0It is negative, then direct current branch positive bus-bar resistance to earth value is infinity, directly
Flow branch road negative busbar resistance to earth value Rn=Un/I0；
If judge the total leakage current I of direct current branch0For just, then direct current branch positive bus-bar resistance to earth value Rp=Up/I0, direct current
Branch road negative busbar resistance to earth value is infinity.
According to transforming plant DC power-supply system of the present invention, described unbalanced bridge mode detection branch insulation electricity
, it is necessary to which testing resistor bridge by switching changes positive pole line-to-earth voltage, negative busbar voltage-to-ground and the total leakage current of branch road during resistance, throw
Enter RL2When, Up、Un、I0Value U respectivelyp1、Un1、I1；Put into RL1When, Up、Un、I0Value U respectivelyp2、Un2、I2, electric current outflow node
For 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；So as to
Have：
I1-Un1/Rx-Up1/Ry=0
I2-Un2/Rx-Up2/Ry=0
Obtain：
Rx=(Up1Un2-Up2Un1)/(Up1I2-Up2I1)
Ry=(Up2Un1-Up1Un2)/(Un1I2-Un2I1)
According to transforming plant DC power-supply system of the present invention, the specific work process that module is checked in the route selection is：
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.
The beneficial effect that the present invention reaches：The DC power system of the present invention can be according to the forward and backward Current Voltage of failure
The amount of calculation of quantity of state and grounding resistance, and the electrical link of three, fault signature identification is carried out, using automatic detecting mould
Formula, the rapidity of balanced bridge and the fault-tolerance of unbalanced bridge can be effectively taken into account, improve and search speed and fault tolerance level, it is real
Existing quick diagnosis is simultaneously fixed a breakdown, and has both been improved the operating efficiency of engineering site, has been reduced again and blindly draw risk caused by road.
Route selection need to only be checked function and be integrated into the transforming plant DC electricity for possessing ground connection inspection route selection Checking Mechanism by the present invention
In the system of source, drift and fault branch are recognized by logic judgment dynamic call unbalanced bridge pattern, relative to existing
The automatic detecting pattern of unbalanced bridge pattern is called in timing, can quickly identify falsely dropping or leaking for DC earthing inspection device
Choosing, the performance of inspection device is improved on the premise of hardware cost is not increased.
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 power-supply system of the present invention, for for the important conventional load of transformer station, relay protection and automatic
Device, telecontrol communication device provide uninterrupted power supply, as shown in figure 1, described transforming plant DC power-supply system include positive bus-bar+
KM and negative busbar-KM, if connecting conventional load, relay protection and automatics, telecontrol communication device and devices for emergency illumination
Dry bar direct current branch, one group of direct-current bridge element, and carried out for the insulation against ground state to transforming plant DC power-supply system
The on-Line Monitor Device 1 of inspection, i.e. inspection device.
As shown in figure 1, balance resistor bridge Rb1 of the direct-current bridge element including two resistance identical measuring resistances compositions,
Rb2；Test resistor bridge RL1, RL2 that two resistance identical measuring resistances are formed；Two control test resistor bridge on-states
Relay switching switch K1, K2.
As shown in figure 4, the voltage detecting input of described on-Line Monitor Device 1, is connected to transforming plant DC power supply system
Positive bus-bar+the KM and negative busbar-KM of system, the branch road leakage current test input of described on-Line Monitor Device 1, are connected to each
DC leakage flow sensor I1, I2 (abbreviation direct current transducer or transformer) of bar direct current branch, the electric leakage to each branch road flows into
Row sampling.
The structure of the online inspection device 1 of described transforming plant DC power-supply system including inspection as shown in figure 9, control mould
Block 10, and be connected with the inspection control module output end dc bus detection module 11, direct current branch detection module and
Module 15 is checked in route selection, and described online inspection device includes inspection control module, and is exported with the inspection control module
The dc bus detection module, direct current branch detection module and route selection of connection is held to check module, described inspection control module is used
The operation of module, the inspection of described dc bus are checked in control dc bus detection module, direct current branch detection module and route selection
The direct-current bridge element that module is used to pass through switching DC power system is surveyed, detection calculates the insulation against ground of positive and negative dc bus
Resistance, the earth fault of positive bus-bar or negative busbar is monitored on-line, described direct current branch detection module is based on detecting
The insulaion resistance of each direct current branch, and the insulaion resistance testing result of more each branch road are calculated, selection determines that earth fault occurs
Fault branch；Described route selection checks module and is used to carry 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.
Described direct current branch detection module includes balanced bridge detection unit 12, unbalanced bridge detection unit 13 and event
Hinder branch road identifying unit 14.Described balanced bridge detection unit 12 uses balanced bridge pattern, exhausted by detecting calculating branch road
Edge resistance, search DC ground fault branch road；Described unbalanced bridge detection unit 13 uses unbalanced bridge pattern, passes through
Switching test resistor bridge changes positive and negative dc bus voltage-to-ground and the total leakage current of branch road, and detection calculates each branch insulation resistance,
Search DC ground fault branch road；Described fault branch identifying unit 14, the insulaion resistance for more each branch road detect knot
Fruit, selection determine that the fault branch of earth fault occurs.
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、Un
Respectively 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、Un
Respectively 180V, -40V, I1May be -0.667mA, -1.167mA；I.e. negative busbar insulation against ground resistance value is corresponding
For 60K Ω and 34K Ω, and 2# branch roads negative busbar has a 10K Ω resistance over the ground, directly alarms, may take 1# branch roads out of simultaneously
Insulation reduce.
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
Transforming plant DC power-supply system route selection check module specific workflow one embodiment as shown in fig. 7, comprises following
Step：
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.
According to one embodiment of the transforming plant DC power-supply system of the present invention, module 15 is checked in described route selection also to be included
Reduction to absurdity checks submodule, and described reduction to absurdity checks submodule and is connected to dc bus detection module 11, according to DC earthing
The busbar grounding resistance tried to achieve during inspection route selection, reversely calculate the estimated value of positive and negative busbar voltage；According to the estimated value
With the difference of the measured value of corresponding voltage, infer that route selection result is wrong.Return below described reduction to absurdity check submodule execution wrong
The step of method 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.
It is preferred real according to one of the transforming plant DC power-supply system for possessing ground connection inspection route selection Checking Mechanism of the present invention
Example is applied, described reduction to absurdity checks submodule and is also connected to fault branch identifying unit 14, according to DC earthing inspection route selection
The positive and negative bus resistance to earth for each branch road tried to achieve in journey, calculates negative busbar and positive bus-bar all-in resistance over the ground, reversely calculate just,
The estimated value of negative busbar voltage；According to the estimated value and the difference of the measured value of corresponding voltage, infer that route selection result is wrong.
It is further comprising the steps of after described 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 pressurepWith U "n：
U"p=U*RyΣ/(RxΣ+RyΣ) (13)
U"n=-U*RxΣ/(RxΣ+RyΣ) (14)
Wherein, U "pFor the estimated value of positive pole line voltage, U "nFor 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 calculatedpWith U "n, with corresponding positive and negative busbar voltage measured value
UpAnd UnIt is compared, if U "pWith U "nAny 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"pWith U "n.If calculate
Go out value U'p、U'n、U"pWith U "nWith 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 (8)
- A kind of 1. transforming plant DC power-supply system, it is characterised in that：Described transforming plant DC power-supply system include positive bus-bar and Negative busbar, for connecting some of conventional load, relay protection and automatics, telecontrol communication device and devices for emergency illumination Direct current branch, for one group of direct-current bridge element of system on-line monitoring, and for pair to transforming plant DC power-supply system Ground state of insulation carries out the on-Line Monitor Device of inspection, and each direct current branch is provided with DC leakage flow sensor；The voltage detecting input of described on-Line Monitor Device, connect the positive bus-bar of transforming plant DC power-supply system and negative mother Line, the branch road leakage current test input of described on-Line Monitor Device, the DC leakage of each direct current branch of connection spread Sensor, the leakage current of each direct current branch is sampled；Described on-Line Monitor Device includes inspection control module, and the direct current being connected with the inspection control module output end Module is checked in bus detection module, direct current branch detection module and route selection, and described inspection control module is used to control direct current female The operation of module is checked in line detection module, direct current branch detection module and route selection, and described dc bus detection module is used to lead to The direct-current bridge element of switching DC power system is crossed, detection calculates the insulation against ground resistance of positive and negative dc bus, to positive bus-bar Or the earth fault of negative busbar is monitored on-line, described direct current branch detection module, which is used to detect, calculates each direct current branch Insulaion resistance, and the insulaion resistance testing result of more each branch road, selection determine that the fault branch of earth fault occurs；Described Route selection checks module and uses the event driven automatic detecting pattern of logic-based, according to the forward and backward Current Voltage of inspection branch trouble Quantity of state and grounding resistance amount of calculation, and the electrical link of three, carry out fault signature identification, avoid fault branch Falsely drop or leak choosing.
- 2. transforming plant DC power-supply system according to claim 1, it is characterised in that described direct-current bridge element includes Two balance resistor bridges, two test resistor bridges, and the relay switching of two controls test resistor bridge on-state Switch, described two balance resistor bridges are separately fixed at dc bus both ends, and described test resistor bridge is cut by relay Switch on-off is changed to dc bus.
- 3. transforming plant DC power-supply system according to claim 1, it is characterised in that the insulation against ground resistance of dc bus Detection uses bridge method, and geodetic point voltage is zero potential, meets formula：Un/Rb1+Up/Rb2+Un/RL1+Up/RL2+Un/Rx+Up/Ry=0Wherein, Up、UnRespectively positive bus-bar, negative busbar voltage；Rb1、Rb2To balance resistor bridge, they are resistance identical standards Resistance；RL1、RL2To test resistor bridge, they are resistance identical measuring resistances；Balance resistor bridge and test resistor bridge numerical value Choose the maximum detectability of the power and electricity leakage sensor that to consider bus bar resistance；Rx、RyFor the insulation against ground electricity of dc bus Resistance.
- 4. transforming plant DC power-supply system according to claim 3, it is characterised in that carried out to bus insulation against ground resistance Turning on and off for switch is switched by relay during measurement, dc bus is calculated over the ground according to Up, Un that measurement obtains Insulaion resistance Rx, Ry, i.e.,：Two relay switchings switch each self-closing, respectively obtain：Un1/Rb1+Up1/Rb2+Un1/RL1+Un1/Rx+Up1/Ry=0Un2/Rb1+Up2/Rb2+Up2/RL2+Un2/Rx+Up2/Ry=0So as to which Rx, Ry value be calculated；Wherein, Up1For input test resistor bridge RL2When positive pole line voltage, Un1For input test resistor bridge RL2When negative busbar electricity Pressure；Up2For input test resistor bridge RL1When positive pole line voltage, Un2For input test resistor bridge RL1When negative busbar voltage.
- 5. transforming plant DC power-supply system according to claim 4, it is characterised in that described direct current branch detection module Including balanced bridge detection unit, unbalanced bridge detection unit and fault branch identifying unit, the detection of described balanced bridge Unit uses balanced bridge pattern, calculates branch insulation resistance by detecting, searches DC ground fault branch road；Described injustice Weighing apparatus electric bridge detection unit use unbalanced bridge pattern, by switching test resistor bridge change positive and negative dc bus voltage-to-ground with The total leakage current of branch road, detection calculate each branch insulation resistance, search DC ground fault branch road；Described fault branch judges single Member, for the insulaion resistance testing result of more each branch road, selection determines that the fault branch of earth fault occurs.
- 6. transforming plant DC power-supply system according to claim 5, it is characterised in that described balanced bridge mode detection During branch insulation resistance, the direction of the total leakage current of direct current branch is first determined whether, positioning DC branch road negative or positive electrode insulating ground, Then according to positive pole line-to-earth voltage or negative busbar voltage-to-ground, insulating resistance value is calculated, is specially：If judge the total leakage current I of direct current branch0It is negative, then direct current branch positive bus-bar resistance to earth value is infinity, and direct current branch is born Bus resistance to earth value Rn=Un/I0；If judge the total leakage current I of direct current branch0For just, then direct current branch positive bus-bar resistance to earth value Rp=Up/I0, direct current branch bears Bus resistance to earth value is infinity.
- 7. transforming plant DC power-supply system according to claim 5, it is characterised in that described unbalanced bridge pattern inspection , it is necessary to which testing resistor bridge by switching changes positive pole line-to-earth voltage, negative busbar voltage-to-ground and branch when surveying branch insulation resistance The total leakage current in road, put into RL2When, Up、Un、I0Value U respectivelyp1、Un1、I1；Put into RL1When, Up、Un、I0Value U respectivelyp2、Un2、 I2, electric current outflow node is positive direction, RyThe positive bus-bar insulation against ground resistance value of certain branch road, RxFor certain branch road negative busbar over the ground Insulating resistance value；I0For the total leakage current of direct current branch, so as to have：I1-Un1/Rx-Up1/Ry=0I2-Un2/Rx-Up2/Ry=0Obtain：Rx=(Up1Un2-Up2Un1)/(Up1I2-Up2I1)Ry=(Up2Un1-Up1Un2)/(Un1I2-Un2I1)。
- 8. transforming plant DC power-supply system according to claim 1, it is characterised in that the specific of module is checked in the route selection The course of work is：S100：The insulation against ground resistance of dc bus is calculated using unbalanced bridge mode detection；S200：Grounding inspection is carried out using balanced bridge pattern；S220：When carrying out ground connection inspection to a certain branch road, judge whether the leakage current of the branch road changes, if leakage current without Change, judges that the branch road has drift fault-free；Otherwise, order performs step S240；S240：Judge whether the branch road 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.
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| CN105676086A (en) * | 2016-01-29 | 2016-06-15 | 山东鲁能智能技术有限公司 | Insulation monitoring system and method having automatic calibration function |
| CN107045092B (en) * | 2017-05-16 | 2023-04-07 | 广东电网有限责任公司惠州供电局 | Intelligent detection device and method for low-voltage alternating-current ring network for station |
| CN108333461B (en) * | 2017-12-26 | 2020-03-24 | 国网浙江省电力公司衢州供电公司 | Electric leakage detection operating system |
| CN113933626A (en) * | 2021-09-30 | 2022-01-14 | 滁州市智宏工程咨询有限责任公司 | Fault detection and correction control method for direct-current system of transformer substation |
| CN114720902B (en) * | 2022-04-07 | 2022-10-14 | 国网黑龙江省电力有限公司佳木斯供电公司 | Direct-current power supply fault rapid isolation system for transformer substation |
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| CN201965190U (en) * | 2010-12-31 | 2011-09-07 | 杭州奥能电源设备有限公司 | Insulation detecting device for direct current system |
| CN102411120B (en) * | 2011-11-28 | 2013-08-07 | 天津市电力公司 | Earth line selection device for converting station direct current system |
| CN103558507A (en) * | 2013-10-29 | 2014-02-05 | 国家电网公司 | Sensor for direct current fault line selection and alternating current interlarding line selection |
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