CN105158539B - Method based on pressure drop cancellation element measurement PT secondary circuit voltage drops - Google Patents
Method based on pressure drop cancellation element measurement PT secondary circuit voltage drops Download PDFInfo
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- CN105158539B CN105158539B CN201510428354.0A CN201510428354A CN105158539B CN 105158539 B CN105158539 B CN 105158539B CN 201510428354 A CN201510428354 A CN 201510428354A CN 105158539 B CN105158539 B CN 105158539B
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Abstract
The invention discloses a kind of circuit based on pressure drop cancellation element measurement PT secondary circuit voltage drops, including be sequentially connected in series PT output ends, PT secondary circuits, pressure drop cancellation element, electric energy meter and and be connected in the equivalent resistance of PT output ends, input draws two-way respectively inside PT output ends and pressure drop cancellation element, all the way by switching K1Equivalent resistance is connected, another way is sequentially connected in series relay K0, voltage sample module, voltage-phase detection module and processor；The inside input of pressure drop cancellation element is provided with switch K2, pressure drop cancellation element internal output terminal, which is provided with, switchs K3, switch K2With switch K3Between be provided with and be used to cut off the bypass that pressure drop cancellation element recovers former PT secondary circuits state.
Description
Technical field
It is particularly a kind of based on pressure drop cancellation element measurement PT bis- the present invention relates to a kind of industrial electrical field of measuring technique
The circuit and method of minor loop pressure drop.
Background technology
In order to effectively reduce DL/T448-2000《Electric energy measuring management technical management code》Specified in all kinds of electric energy meters
The pressure drop of amount device PT secondary circuits, it is domestic to occur at present using the production of voltage follower principle for eliminating PT secondary returnings
The device of road pressure drop.The functional characteristics of voltage follower is that output voltage is equal to input voltage, without phase difference；Input impedance is very
Greatly, follower front end electric current very little, close to zero；Output impedance very little, can be with bringing onto load.
Eliminate PT secondary circuit voltage drops in order to realize and can ensure PT measuring accuracies simultaneously, the access in parallel of the PT ports of export with
The precision resistance module of electric energy meter impedance matching is a kind of effective method.Resistive module and voltage follower module are in PT bis- times
Switching, the accurate pressure drop cancellation element function element module for eliminating pressure drop, protecting former measurement loop of composition are equivalent simultaneously in loop
The resistance Zx of resistance meets below equation：Zx=Z+Z2/ Zin, wherein Z represent electric energy meter impedance, and Zin represents voltage follower mould
The impedance of block input, electric energy meter is equal to be run at PT ends.
DL/T448‐2000《Electric energy measuring management technical management code》In define all kinds of electric power meter PT bis- times
The allowed band and measurement period of loop pressure drop.The special PT secondary circuit voltage drops measuring instrument of domestic production uses error of measurement method mostly
Direct measurement or indirect host and slave processors mensuration.
Work ticket, which is held, with staff during error of measurement method direct measurement measures work to substation field.In actual measurement
Problems with operation be present：
(1) manually it is difficult to continuously measure, measurement is few for the data of analysis, and operating efficiency is low.
(2) the artificial folding and unfolding at the scene of measurement is twisted shielded cable every time, potential safety hazard be present.
(3) Insulation test must be carried out before each measurement point measures wiring every time by being twisted shielded cable.
(4) measurement every time, the time that data are obtained for measurement are considerably less than field connection, twisted shielded cable folding and unfolding
Line, twisted shielded cable Insulation test, the time of defect elimination.
(5) most of data computing function that provides is, it is necessary to manually carry out data analysis.
Solved with indirect host and slave processors mensuration with error of measurement method (2) measured directly (3) (4) (5) problem, but in reality
New problem is brought in measurement work：
(1) radio communication scene is easily disturbed, and staff scene must be found repeatedly can ensure the wireless of communication
Electric aerial position；Host and slave processors GPS scenes must trace into communications satellite respectively and can measure.
(2) the necessary host and slave processors configuration of equipment, main frame can not be complete as the core failure measurement of measurement, data processing
Into equipment guarantee is not high；
(3) because host and slave processors are supporting, equipment repeats to purchase.
No matter use error of measurement method direct measurement or measure PT secondary circuit voltage drops, staff with indirect host and slave processors mensuration
Must all hold work ticket, take measurement equipment, ride public transportation means measures work, road, work on the spot to substation field
Time is longer, and job costs are higher.
The content of the invention
Goal of the invention：The technical problems to be solved by the invention are in view of the shortcomings of the prior art, there is provided one kind is based on pressure
The circuit and method of cancellation element measurement PT secondary circuit voltage drops drop.
In order to solve the above-mentioned technical problem, the invention discloses one kind based on pressure drop cancellation element measurement PT secondary circuit pressures
The circuit of drop, including be sequentially connected in series PT output ends, PT secondary circuits, pressure drop cancellation element, electric energy meter and and be connected in PT
The equivalent resistance of output end, input draws two-way respectively inside PT output ends and pressure drop cancellation element, passes through switch all the way
K1Equivalent resistance is connected, another way is sequentially connected in series relay K0, voltage sample module, voltage-phase detection module and processor；
The inside input of pressure drop cancellation element is provided with switch K2, switch is provided between pressure drop cancellation element internal output terminal and electric energy meter
K3, switch K2With switch K3Between be provided with and be used to cut off the bypass of pressure drop cancellation element.
The invention also discloses a kind of PT secondary circuit voltage drops cancellation element based on voltage follower principle to measure PT bis-
The method of minor loop pressure drop, including：
Including be sequentially connected in series PT output ends, PT secondary circuits, pressure drop cancellation element, electric energy meter, and and be connected in PT
The equivalent resistance of output end, drawn between PT output ends and PT secondary circuits all the way by switching K1Connect equivalent resistance, PT
Drawn respectively between input inside secondary circuit and pressure drop cancellation element and be sequentially connected in series relay K all the way0, voltage sample mould
Block, voltage-phase detection module and CPU processor；Input is provided with switch K inside pressure drop cancellation element2, pressure drop, which eliminates, to be filled
Put and switch K is provided between internal output terminal and electric energy meter3, switch K2With switch K3Between be provided be used for cut off pressure drop cancellation element
Bypass.
In the present invention, including：
When pressure drop device normal operation works, K is switched1、K2、K3Close；Input measurement instructs, CPU processor control electricity
Press measurement module relay K0Close；CPU processor command voltage sampling module sampling pressure drop cancellation element input terminal voltage UI,
Voltage UICorresponding three-phase voltage amplitude be VI(A)、VI(B)、VI(C), phase ΦI(A)、ΦI(B)、ΦI(C), signal feeding voltage,
Phase detecting module is calculated, analyzed, being compared, measuring condition judgment, and the data of coincidence measurement condition are stored at CPU
Manage in device；Switch K2With switch K3Connection bypass, switch K1Simultaneously switch off excision pressure drop cancellation element and recover former PT secondary circuits shape
State, voltage sample module is in pressure drop cancellation element input sampling pressure drop cancellation element output end voltage UO, because switch K2With open
Close K3Connection bypass, UOTo UDBetween wire length it is very short, pressure drop cancellation element output end voltage UOEqual to electric power meter end voltage UD,
Its three-phase voltage amplitude is VO(A)、VO(B)、VO(C), phase ΦO(A)、ΦO(B)、ΦO(C), signal feeding voltage, phase-detection mould
Block is calculated, analyzed, being compared, measuring condition judgment, and the data of coincidence measurement condition, which are stored in CPU processor, goes forward side by side
Row processing；Voltage UOSwitch K is completed in sampling2With switch K3Pressure drop cancellation element, switch K are connected immediately1Close simultaneously, pressure drop disappears
Except device puts into operation；
Measurement terminates, automatic to disconnect relay K0；
With reference to the measurement in pressure drop cancellation element to load current, PT secondary circuit load measurements are realized.
In the present invention, the sampling pressure drop when pressure drop cancellation element runs work of CPU processor command voltage sampling module disappears
Except device input terminal voltage UI, voltage, phase detecting module, which calculated, analyzed, compared, measures condition judgment includes：
Within the setting time cycle, voltage measurement module continuously measures one group of voltage vector UIAfterwards by this group of voltage vector UI
Calculate in voltage magnitude, analyze with carrying out voltage magnitude, voltage-phase in phase detecting module, compared with；Voltage magnitude is used
Variance method carries out data processing, including：
VI(A)=(V(A)1+V(A)2+…+V(A)n)/n,
VI(B)=(V(B)1+V(B)2+…+V(B)n)/n,
VI(C)=(V(C)1+V(C)2+…+V(C)n)/n,
S2 I(A)=((V(A)1-VI(A))2+(V(A)2-VI(A))2+…+(V(A)n-VI(A))2)/n,
S2 I(B)=((V(B)1-VI(B))2+(V(B)2-VI(B))2+…+(V(B)n-VI(B))2)/n,
S2 I(C)=((V(C)1-VI(C))2+(V(C)2-VI(C))2+…+(V(C)n-VI(C))2)/n,
SI 2=S2 I(A)+S2 I(B)+S2 I(C)
Wherein V(A)n、V(B)n、V(C)nRespectively pressure drop cancellation element input terminal voltage UICorresponding three-phase voltage UI(A)、
UI(B)、UI(C)In n-th of measured value voltage magnitude, VI(A)、VI(B)、VI(C)The respectively voltage of n measured value of three-phase voltage
Amplitude arithmetic average；SI 2It is worth to judge whether current voltage meets the steady measuring condition of line voltage of setting；S2 I(A)、
S2 I(B)、S2 I(C)Respectively SI 2Middle corresponding subitem；
As the voltage magnitude scope for judging voltage pulsation, with (V(A)n-VI(A)) exemplified by, this case require its absolute value≤
0.01 (V) (may also require that its absolute value≤0.015 (V) etc., scope range of the fluctuation of voltage broadens, and measurement error becomes big), (V(A)n-
VI(A))2≤0.0001(V2), then S2 I(A)=((V(A)1-VI(A))2+(V(A)2-VI(A))2+…+(V(A)n-VI(A))2)/n≤0.0001
(V2)
Similarly, S2 I(B)≤0.0001(V2), S2 I(C)≤0.0001(V2)。
The direction of error and voltage pulsation in view of measurement and scope,
Set SI 2=S2 I(A)+S2 I(B)+S2 I(C)=0.0001+0.0001+0.0001=0.0003 (V2) it is used as line voltage
Whether stable criterion：
As measurement assay value SI 2During more than setting value 0.0003, it is judged as not meeting the steady measuring condition of line voltage, then
The measuring section of one setting of automatic time delay, restart to measure work；
As measurement assay value SI 2During less than or equal to setting value 0.0003, it is judged as the measuring condition for meeting setting, will measures
Voltage magnitude VI(A)、VI(B)、VI(C), phase ΦI(A)、ΦI(B)、ΦI(C)Preserve；
ΦI(A)=(Φ(A)1+Φ(A)2+…+Φ(A)n)/n,
ΦI(B)=(Φ(B)1+Φ(B)2+…+Φ(B)n)/n,
ΦI(C)=(Φ(C)1+Φ(C)2+…+Φ(C)n)/n,
Φ(A)n、Φ(B)n、Φ(C)nFor voltage UIThe three-phase voltage phase of n-th of measured value of middle corresponding subitem, ΦI(A)、
Φ(B)、ΦI(C)For the arithmetic average of n measured value of three-phase voltage phase.
In the present invention, voltage sample module samples pressure drop cancellation element output end electricity when recovering former PT secondary circuits state
Press UO, voltage, phase detecting module are calculated, analyzed, being compared, measuring condition judgment, the data of coincidence measurement condition
It is stored in CPU processor and is handled, is comprised the following steps：
Voltage UIK will be switched after the completion of sampling simultaneously immediately1Disconnect, switch K2、K3The bypass of pressure drop cancellation element is closed,
Pressure drop cancellation element is out of service, and PT secondary circuits are switched to former loop state, and one is measured immediately within the time cycle of setting
Group voltage UO, voltage UOCorresponding three-phase voltage amplitude is VO(A)、VO(B)、VO(C), three-phase voltage phase be ΦO(A)、ΦO(B)、
ΦO(C)；Moment is measured by K1、K2、K3Close, pressure drop cancellation element is put into operation；By this group of voltage vector U of measurementO
Calculates in voltage magnitude, analyze with carrying out voltage magnitude, voltage-phase in phase detecting module, compared with, to voltage magnitude use
Variance method carries out data processing, including：
VO(A)=(VO(A)1+VO(A)2+…+VO(A)n)/n,
VO(B)=(VO(B)1+VO(B)2+…+VO(B)n)/n,
VO(C)=(VO(C)1+VO(C)2+…+VO(C)n)/n,
S2 O(A)=((VO(A)1-VO(A))2+(VO(A)2-VO(A))2+…+(VO(A)n-VO(A))2)/n,
S2 O(B)=((VO(B)1-VO(B))2+(VO(B)2-VO(B))2+…+(VO(B)n-VO(B))2)/n,
S2 O(C)=((VO(C)1-VO(C))2+(VO(C)2-VO(C))2+…+(VO(C)n-VO(C))2)/n,
SO 2=S2 O(A)+S2 O(B)+S2 O(C),
Wherein VO(A)n、VO(B)n、VO(C)nFor voltage vector UOThree-phase voltage measuring values in n-th of measured value voltage
Amplitude, VO(A)、VO(B)、VO(C)The respectively voltage magnitude arithmetic average of n measured value of three-phase voltage；SO 2It is worth current to judge
Whether voltage meets the steady measuring condition of line voltage of setting, S2 O(A)、S2 O(B)、S2 O(C)Respectively SO 2Middle corresponding subitem；
Same setting SO 2=S2 O(A)+S2 O(B)+S2 O(C)=0.0001+0.0001+0.0001=0.0003 (V2) it is used as power network
The whether stable criterion of voltage：
As measurement assay value SO 2During more than setting value 0.0003, it is judged as not meeting the steady measuring condition of line voltage, then
The measuring section of one setting of automatic time delay, remeasures voltage UI；
As measurement assay value SO 2During less than or equal to setting value 0.0003, it is judged as the measuring condition for meeting setting, will be above-mentioned
Measure voltage magnitude VO(A)、VO(B)、VO(C), phase ΦO(A)、ΦO(B)、ΦO(C)Preserve,
ΦO(A)=(ΦO(A)1+ΦO(A)2+…+ΦO(A)n)/n,
ΦO(B)=(ΦO(B)1+ΦO(B)2+…+ΦO(B)n)/n,
ΦO(C)=(ΦO(C)1+ΦO(C)2+…+ΦO(C)n)/n,
Wherein ΦO(A)n、ΦO(B)n、ΦO(C)nRespectively ΦO(A、B、C)In corresponding n-th of measured value of three-phase voltage voltage
Amplitude, ΦO(A)、ΦO(B)、ΦO(C)The respectively arithmetic average of n measured value of three-phase voltage.
In the present invention, calculate within a processor, analyze, compare VO(A)、
VO(B)、VO(C)、VI(A)、VI(B)、VI(C)、ΦO(A)、ΦO(B)、ΦO(C)、ΦI(A)、ΦI(B)、ΦI(C)Former PT can be drawn
Secondary circuit table end and PT output end voltages vector ratio is poor, angular difference, and then calculating PT secondary circuits go out pressure drop relative value and
The composition error of pressure drop：
Calculation formula wherein than poor f is：
f(A)=△ V(A)/VI(A)(%), △ V(A)=VO(A)-VI(A)(V),
f(B)=△ V(B)/VI(B)(%), △ V(B)=VO(B)-VI(B)(V),
f(C)=△ V(C)/VI(C)(%), △ V(C)=VO(C)-VI(C)(V),
f(A)、f(B)、f(C)Corresponding three-phase subitem respectively than poor f；
Wherein angular difference δ calculation formula is：Unit is (')
δ(A)=ΦO(A)-ΦI(A),
δ(B)=ΦO(B)-ΦI(B),
δ(C)=ΦO(C)-ΦI(C),
δ(A)、δ(B)、δ(C)Respectively angular difference δ corresponding three-phase subitem；
Pressure drop relative value △ u/UICalculation formula be：
Calculating △ u(A)/UI(A)、△u(B)/UI(B)、△u(C)/UI(C)When f correspond to f respectively(A)、f(B)、f(C), δ is right respectively
It should be δ(A)、δ(B)、δ(C)。
The present invention increases a voltage measurement mould using in the pressure drop cancellation element input based on voltage follower principle
Block, measurement apparatus input three-phase voltage vector.Voltage measurement module by voltage sample module, voltage and phase detecting module,
CPU module, display module, communication module composition；CPU module, display module, communication mould can also be shared with pressure drop cancellation element
Block.The inventive method can make it that the PT secondary circuit voltage drops cancellation element based on the manufacture of voltage follower principle both can be accurate
PT secondary circuit voltage drops are eliminated, again can be with on-line measurement PT secondary circuit voltage drops.
The present invention has following advantage：
1st, new method is provided for PT secondary circuit voltage drop measurements.New method solves current PT secondary circuit voltage drops, born
Lotus measurement work in it is time consuming, the low problem of potential safety hazard, efficiency be present.
2nd, the public circuit resource of pressure drop cancellation element is made full use of, is only adopted in pressure drop cancellation element input increase voltage
Egf block can be achieved with on-line measurement PT secondary circuit voltage drops, load with voltage, phase detecting module.
3rd, unmanned automatic measurement is remotely realized, saves a large amount of artificial, transports, business travel cost.Measuring the work period can be with
Shorten, technological means is provided to change the measurement work management of PT secondary circuits.
4th, realize that the cost of measurement function is greatly lowered.
Brief description of the drawings
The present invention is done with reference to the accompanying drawings and detailed description and further illustrated, of the invention is above-mentioned
And/or otherwise advantage will become apparent.
Fig. 1 is schematic structural view of the invention.
Embodiment
Embodiment
As shown in figure 1, the present embodiment increases a voltage measurement module, measurement input in the input of pressure drop cancellation element
Hold three-phase voltage vector.
Voltage measurement module is not less than 0.1% voltage sample module, voltage and phase-detection mould by 1 group of measurement accuracy
Block, processor (CPU module), processor can link display module and communication module respectively；Wherein CPU module, display module,
Communication module can also share with pressure drop cancellation element.
The present embodiment Method And Principle：Pressure drop device puts into operation and during normal work, K1、K2、K3Close, voltage measurement
Module measures one group of voltage vector UI, according to based on the pressure drop cancellation element operation principle of voltage follower principle it is recognised that UI
It is in close proximity to now PT output end voltages U, and now PT output end voltages U is in close proximity to pressure drop device and do not put into operation
When (K2、K3Close device bypass, K1Disconnect) PT secondary circuit PT output end voltages UP, ignore UIWith UPMinimum error,
Completely it is considered that U in engineeringIEqual to UP.(the K when pressure drop device is out of service2、K3Close device bypass, K1Disconnect), PT
Secondary circuit restores to the original state, and voltage measurement module measures one group of voltage vector UO, according to the pressure drop based on voltage follower principle
Cancellation element operation principle is it is recognised that UOOriginal PT secondary circuits electric energy meter input when not put into operation equal to pressure drop device
Voltage UD.As measurement UIWith UOTime interval enough in short-term, it is believed that PT output voltages do not change, so, by voltage to
Measure UIWith UOCalculates in voltage magnitude, analyze with carrying out voltage magnitude, voltage-phase in phase detecting module, compared with, it is possible to must
Go out former PT secondary circuits table end and PT output end voltages vector ratio is poor, angular difference, calculate pressure drop relative value and secondary circuit
The composition error of pressure drop.
Analysis measurement data obtain UI, its three-phase voltage amplitude is VI(A)、VI(B)、VI(C), three-phase voltage phase be ΦI(A)、
ΦI(B)、ΦI(C).Error is produced to measurement by voltage ripple of power network to reduce PT voltages, measurement work starts first in setting
Between in the cycle (value natural number, such as 5 seconds) voltage measurement module continuously measure one group of voltage vector UIAfterwards by this group of voltage to
Measure UICalculate in voltage magnitude, analyze with carrying out voltage magnitude, voltage-phase in phase detecting module, compared with, to voltage magnitude
Data processing is carried out using variance method：
VI(A)=(V(A)1+V(A)2+…+V(A)n)/n,
VI(B)=(V(B)1+V(B)2+…+V(B)n)/n,
VI(C)=(V(C)1+V(C)2+…+V(C)n)/n,
S2 I(A)=((V(A)1-VI(A))2+(V(A)2-VI(A))2+…+(V(A)n-VI(A))2)/n,
S2 I(B)=((V(B)1-VI(B))2+(V(B)2-VI(B))2+…+(V(B)n-VI(B))2)/n,
S2 I(C)=((V(C)1-VI(C))2+(V(C)2-VI(C))2+…+(V(C)n-VI(C))2)/n,
SI 2=S2 I(A)+S2 I(B)+S2 I(C)
Wherein V(A)n、V(B)n、V(C)nFor UI(A)、UI(B)、UI(C)The three-phase voltage amplitude of n-th of measured value in measured value, if
A fixed SI 2Value (this numerical value with hits n about) steadily measures bar to judge whether current voltage meets the line voltage of setting
Part.As measurement assay value SI 2During more than setting value, it is judged as not meeting the steady measuring condition of line voltage, then automatic time delay one
The measuring section of setting, restart to measure work.As measurement assay value SI 2During less than or equal to setting value, it is judged as meeting and sets
Fixed measuring condition, voltage magnitude V will be measuredI(A)、VI(B)、VI(C), phase ΦI(A)、ΦI(B)、ΦI(C)Preserve；
ΦI(A)=(Φ(A)1+Φ(A)2+…+Φ(A)n)/n,
ΦI(B)=(Φ(B)1+Φ(B)2+…+Φ(B)n)/n,
ΦI(C)=(Φ(C)1+Φ(C)2+…+Φ(C)n)/n,
Φ(A)n、Φ(B)n、Φ(C)nFor UI(A)、UI(B)、UI(C)The three-phase voltage phase of n-th of measured value in measured value.
Analysis measurement data obtain UO, its three-phase voltage amplitude is VO(A)、VO(B)、VO(C), three-phase voltage phase be ΦO(A)、
ΦO(B)、ΦO(C).Complete sampling UIK1 is disconnected simultaneously immediately afterwards, K2, K3 close device bypass, pressure drop cancellation element exits
Operation, PT secondary circuits are switched to former loop state, and (such as 2 seconds) measure one group of U immediately within the time cycle of settingO。UISampling
Complete moment to close K1, K2, K3, pressure drop cancellation element is put into operation.By this group of U of measurementOIn voltage magnitude and phase
Progress voltage magnitude, voltage-phase are calculated, analyze, compared in detection module, and voltage magnitude is carried out at data using variance method
Reason：
VO(A)=(VO(A)1+VO(A)2+…+VO(A)n)/n,
VO(B)=(VO(B)1+VO(B)2+…+VO(B)n)/n,
VO(C)=(VO(C)1+VO(C)2+…+VO(C)n)/n,
S2 O(A)=((VO(A)1-VO(A))2+(VO(A)2-VO(A))2+…+(VO(A)n-VO(A))2)/n,
S2 O(B)=((VO(B)1-VO(B))2+(VO(B)2-VO(B))2+…+(VO(B)n-VO(B))2)/n,
S2 O(C)=((VO(C)1-VO(C))2+(VO(C)2-VO(C))2+…+(VO(C)n-VO(C))2)/n,
SO 2=S2 O(A)+S2 O(B)+S2 O(C)
Wherein VO(A)、VO(B)、VO(C)nFor voltage vector UOThe three-phase voltage amplitude of n-th of measured value in measured value, setting
One SO 2Value (this numerical value with hits n about) steadily measures bar to judge whether current voltage meets the line voltage of setting
Part.As measurement assay value SO 2During more than setting value, it is judged as not meeting the steady measuring condition of line voltage, then automatic time delay one
The measuring section of setting, again from VIStart to measure work.As measurement assay value SO 2During less than or equal to setting value, it is judged as according with
The measuring condition of setting is closed, by above-mentioned measurement voltage magnitude data VO(A)、VO(B)、VO(C), phase data ΦO(A)、ΦO(B)、ΦO(C)
Preserve,
ΦO(A)=(ΦO(A)1+ΦO(A)2+…+ΦO(A)n)/n,
ΦO(B)=(ΦO(B)1+ΦO(B)2+…+ΦO(B)n)/n,
ΦO(C)=(ΦO(C)1+ΦO(C)2+…+ΦO(C)n)/n,
ΦO(A)、n、ΦO(B)、n、ΦO(C)nFor VOThe three-phase voltage phase of n-th of measured value in measured value.
The voltage U obtained during by coincidence measurement conditionI(voltage magnitude VIWith phase ΦI) and UO(voltage magnitude VOWith phase
ΦO) carry out voltage magnitude, voltage-phase and calculates, analyze, compare, you can it is electric with PT output ends to obtain former PT secondary circuits table end
The ratio of the amount of pressing to is poor, angular difference, calculates pressure drop relative value and the composition error of secondary circuit voltage drop.Even if line voltage has ripple
It is dynamic, measure the different time points more and obtain pressure drop average value several times and be enough what smooth voltage ripple of power network was brought in engineering practice
Measurement error.
The present embodiment measuring method：
(1) on-site manual measures：In pressure drop device normal work, K1、K2、K3Close；It is manually entered measurement instruction,
By cpu instruction voltage measurement module relay K0Close, device measures automatically.Cpu instruction UIVoltage sample, voltage, phase
Detection module is calculated, analyzed, being compared, measuring condition judges, the data of coincidence measurement condition are stored in CPU, and pressure drop disappears
Except device is cut off, UOVoltage sample, voltage, phase detecting module are calculated, analyzed, being compared, measuring condition judges, meet survey
The data of amount condition are stored in CPU and handled, and pressure drop cancellation element puts into operation；The display of measurement data result scene,
Measurement data result can be transmitted to system background by communication module and is further processed.Measurement terminates, and disconnects relay automatically
Device K0。
(2) remote auto measures：In pressure drop device normal work, K1、K2、K3Close；Measurement instruction is assigned on backstage,
By cpu instruction voltage measurement module relay K0Close, device measures automatically.Cpu instruction UIVoltage sample, voltage, phase
Detection module is calculated, analyzed, being compared, measuring condition judges, the data of coincidence measurement condition are stored in CPU, and pressure drop disappears
Except device is cut off, UOVoltage sample, voltage, phase detecting module are calculated, analyzed, being compared, measuring condition judges, meet survey
The data of amount condition are stored in CPU and handled, and pressure drop cancellation element puts into operation；The display of measurement data result scene,
Measurement data result can be transmitted to system background by communication module and is further processed.Measurement terminates, and disconnects relay automatically
Device K0。
(3) measurement in pressure drop cancellation element to load current is combined, realizes PT secondary circuit load measurements, the two is approximate
It is equal.
Voltage measurement module forms the standalone module separated with pressure drop cancellation element, and plug-in is used with pressure drop cancellation element
Connection；It is easy to the combination of overall pressure drop cancellation element function；It can also disperse to be integrated into pressure drop cancellation element.
Voltage measurement module working power is provided by pressure drop device working power.
The invention provides a kind of circuit based on pressure drop cancellation element measurement PT secondary circuit voltage drops, the skill is implemented
The method and approach of art scheme are a lot, and described above is only the preferred embodiment of the present invention, it is noted that are led for this technology
For the those of ordinary skill in domain, under the premise without departing from the principles of the invention, some improvements and modifications can also be made, these
Improvements and modifications also should be regarded as protection scope of the present invention.The available prior art of each part being not known in the present embodiment
Realized.
Claims (4)
1. a kind of method of the PT secondary circuit voltage drops cancellation element measurement PT secondary circuit voltage drops based on voltage follower principle,
This method runs on the circuit based on pressure drop cancellation element measurement PT secondary circuit voltage drops, and the circuit includes the PT being sequentially connected in series
Output end, PT secondary circuits, pressure drop cancellation element, electric energy meter, and and be connected in the equivalent resistance of PT output ends, its feature exists
In being drawn between PT output ends and PT secondary circuits all the way by switching K1Connect equivalent resistance, PT secondary circuits and pressure drop
Drawn respectively between input inside cancellation element and be sequentially connected in series relay K all the way0, voltage sample module, voltage-phase detection
Module and CPU processor；Input is provided with switch K inside pressure drop cancellation element2, pressure drop cancellation element internal output terminal and electricity
Switch K can be provided between table3, switch K2With switch K3Between be provided with and be used to cut off the bypass of pressure drop cancellation element；
Characterized in that, methods described includes：
When pressure drop device normal operation works, K is switched1、K2、K3Close；Input measurement is instructed, and CPU processor control voltage is surveyed
Measure module relay K0Close；CPU processor command voltage sampling module sampling pressure drop cancellation element input terminal voltage UI, voltage
UICorresponding three-phase voltage amplitude be VI(A)、VI(B)、VI(C), phase ΦI(A)、ΦI(B), Φ I (C), signal be sent into voltage, phase
Detection module is calculated, analyzed, being compared, measuring condition judgment, and the data of coincidence measurement condition are stored in CPU processor
In；Switch K2With switch K3Connection bypass, switch K1Simultaneously switch off excision pressure drop cancellation element and recover former PT secondary circuits state,
Voltage sample module is in pressure drop cancellation element input sampling pressure drop cancellation element output end voltage UO, the output of pressure drop cancellation element
Terminal voltage UOEqual to electric power meter end voltage UD, its three-phase voltage amplitude is VO(A)、VO(B)、VO(C), phase ΦO(A)、ΦO(B)、
ΦO(C), signal is sent into voltage, phase detecting module is calculated, analyzed, compared, measuring condition judgment, coincidence measurement bar
The data of part are stored in CPU processor and handled；Voltage UOSwitch K is completed in sampling2With switch K3Connection pressure drop immediately disappears
Except device, switch K1Close simultaneously, pressure drop cancellation element puts into operation；
Measurement terminates, automatic to disconnect relay K0；
With reference to the measurement in pressure drop cancellation element to load current, PT secondary circuit load measurements are realized.
2. according to the method for claim 1, it is characterised in that CPU processor command voltage sampling module eliminates in pressure drop
Pressure drop cancellation element input terminal voltage U is sampled when plant running worksI, voltage, phase detecting module are calculated, analyzed, being compared
Compared with, measure condition judgment and include：
Within the setting time cycle, voltage measurement module continuously measures one group of voltage vector UIAfterwards by this group of voltage vector UIIn electricity
Pressure amplitude value calculates with carrying out voltage magnitude, voltage-phase in phase detecting module, analyzes, compared with；Variance is used to voltage magnitude
Method carries out data processing, including：
VI(A)=(V(A)1+V(A)2+…+V(A)n)/n,
VI(B)=(V(B)1+V(B)2+…+V(B)n)/n,
VI(C)=(V(C)1+V(C)2+…+V(C)n)/n,
S2 I(A)=((V(A)1-VI(A))2+(V(A)2-VI(A))2+…+(V(A)n-VI(A))2)/n,
S2 I(B)=((V(B)1-VI(B))2+(V(B)2-VI(B))2+…+(V(B)n-VI(B))2)/n,
S2 I(C)=((V(C)1-VI(C))2+(V(C)2-VI(C))2+…+(V(C)n-VI(C))2)/n,
SI 2=S2 I(A)+S2 I(B)+S2 I(C)
Wherein V(A)n、V(B)n、V(C)nRespectively pressure drop cancellation element input terminal voltage UICorresponding three-phase voltage UI(A)、UI(B)、UI(C)
In n-th of measured value voltage magnitude, VI(A)、VI(B)、VI(C)The voltage magnitude of respectively n measured value of three-phase voltage counts
Average value；SI 2It is worth to judge whether current voltage meets the steady measuring condition of line voltage of setting；S2 I(A)、S2 I(B)、S2 I(C)Point
Wei not SI 2Middle corresponding subitem；
As measurement assay value SI 2During more than setting value 0.0003, it is judged as not meeting the steady measuring condition of line voltage, then automatically
The measuring section of one setting of delay, restart to measure work；
As measurement assay value SI 2During less than or equal to setting value 0.0003, it is judged as the measuring condition for meeting setting, voltage will be measured
Amplitude VI(A)、VI(B)、VI(C), phase ΦI(A)、ΦI(B)、ΦI(C)Preserve；
ΦI(A)=(Φ(A)1+Φ(A)2+…+Φ(A)n)/n,
ΦI(B)=(Φ(B)1+Φ(B)2+…+Φ(B)n)/n,
ΦI(C)=(Φ(C)1+Φ(C)2+…+Φ(C)n)/n,
Φ(A)n、Φ(B)n、Φ(C)nFor voltage UIThe three-phase voltage phase of n-th of measured value of middle corresponding subitem, ΦI(A)、Φ(B)、
ΦI(C)For the arithmetic average of n measured value of three-phase voltage phase.
3. according to the method for claim 2, it is characterised in that voltage sample module is when recovering former PT secondary circuits state
Sample pressure drop cancellation element output end voltage UO, voltage, phase detecting module are calculated, are analyzed, are compared, measure condition
Judge, the data of coincidence measurement condition are stored in CPU processor and handled, comprised the following steps：
Voltage UIK will be switched after the completion of sampling simultaneously immediately1Disconnect, switch K2、K3The bypass of pressure drop cancellation element is closed, pressure drop disappears
Except device is out of service, PT secondary circuits are switched to former loop state, measure one group of voltage immediately within the time cycle of setting
UO, voltage UOCorresponding three-phase voltage amplitude is VO(A)、VO(B)、VO(C), three-phase voltage phase be ΦO(A)、ΦO(B)、ΦO(C)；Measurement
Moment is completed by K1、K2、K3Close, pressure drop cancellation element is put into operation；By this group of voltage vector U of measurementOIn voltage magnitude
Calculates, analyze with carrying out voltage magnitude, voltage-phase in phase detecting module, compared with, to voltage magnitude using variance method progress
Data processing, including：
VO(A)=(VO(A)1+VO(A)2+…+VO(A)n)/n,
VO(B)=(VO(B)1+VO(B)2+…+VO(B)n)/n,
VO(C)=(VO(C)1+VO(C)2+…+VO(C)n)/n,
S2 O(A)=((VO(A)1-VO(A))2+(VO(A)2-VO(A))2+…+(VO(A)n-VO(A))2)/n,
S2 O(B)=((VO(B)1-VO(B))2+(VO(B)2-VO(B))2+…+(VO(B)n-VO(B))2)/n,
S2 O(C)=((VO(C)1-VO(C))2+(VO(C)2-VO(C))2+…+(VO(C)n-VO(C))2)/n,
SO 2=S2 O(A)+S2 O(B)+S2 O(C),
Wherein VO(A)n、VO(B)n、VO(C)nFor voltage vector UOThree-phase voltage measuring values in n-th of measured value voltage magnitude,
VO(A)、VO(B)、VO(C)The respectively voltage magnitude arithmetic average of n measured value of three-phase voltage；SO 2It is worth to judge that current voltage is
The no steady measuring condition of line voltage for meeting setting, S2 O(A)、S2 O(B)、S2 O(C)Respectively SO 2Middle corresponding subitem；
As measurement assay value SO 2During more than setting value 0.0003, it is judged as not meeting the steady measuring condition of line voltage, then automatically
The measuring section of one setting of delay, remeasures voltage UI；
As measurement assay value SO 2During less than or equal to setting value 0.0003, it is judged as the measuring condition for meeting setting, by above-mentioned measurement
Voltage magnitude VO(A)、VO(B)、VO(C), phase ΦO(A)、ΦO(B)、ΦO(C)Preserve,
ΦO(A)=(ΦO(A)1+ΦO(A)2+…+ΦO(A)n)/n,
ΦO(B)=(ΦO(B)1+ΦO(B)2+…+ΦO(B)n)/n,
ΦO(C)=(ΦO(C)1+ΦO(C)2+…+ΦO(C)n)/n,
Wherein ΦO(A)n、ΦO(B)n、ΦO(C)nRespectively ΦO(A、B、C)In corresponding n-th of measured value of three-phase voltage voltage magnitude,
ΦO(A)、ΦO(B)、ΦO(C)The respectively arithmetic average of n measured value of three-phase voltage.
4. according to the method for claim 3, it is characterised in that calculate within a processor, analyze, compare VO(A)、VO(B)、
VO(C)、VI(A)、VI(B)、VI(C)、ΦO(A)、ΦO(B)、ΦO(C)、ΦI(A)、ΦI(B)、ΦI(C)Former PT secondary circuits table end can be drawn
With PT output end voltages vector ratio is poor, angular difference, and then calculate that PT secondary circuits go out pressure drop relative value and the comprehensive of pressure drop misses
Difference：
Calculation formula wherein than poor f is：
f(A)=△ V(A)/VI(A), △ V(A)=VO(A)-VI(A),
f(B)=△ V(B)/VI(B), △ V(B)=VO(B)-VI(B),
f(C)=△ V(C)/VI(C), △ V(C)=VO(C)-VI(C),
f(A)、f(B)、f(C)Corresponding three-phase subitem respectively than poor f；
Wherein angular difference δ calculation formula is：
δ(A)=ΦO(A)-ΦI(A),
δ(B)=ΦO(B)-ΦI(B),
δ(C)=ΦO(C)-ΦI(C),
δ(A)、δ(B)、δ(C)Respectively angular difference δ corresponding three-phase subitem；
Pressure drop relative value △ u/UICalculation formula be：
<mrow>
<mi>&Delta;</mi>
<mi>u</mi>
<mo>/</mo>
<msub>
<mi>U</mi>
<mi>I</mi>
</msub>
<mo>=</mo>
<msqrt>
<mrow>
<msup>
<mi>f</mi>
<mn>2</mn>
</msup>
<mo>+</mo>
<msup>
<mrow>
<mo>(</mo>
<mn>0.0291</mn>
<mo>*</mo>
<mi>&delta;</mi>
<mo>)</mo>
</mrow>
<mn>2</mn>
</msup>
</mrow>
</msqrt>
<mrow>
<mo>(</mo>
<mi>%</mi>
<mo>)</mo>
</mrow>
<mo>,</mo>
</mrow>
Calculating △ u(A)/UI(A)、△u(B)/UI(B)、△u(C)/UI(C)When f correspond to f respectively(A)、f(B)、f(C), δ corresponds to respectively
δ(A)、δ(B)、δ(C)。
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| CN110133562A (en) * | 2019-04-03 | 2019-08-16 | 华电电力科学研究院有限公司 | A kind of Secondary Circuit of Potential Transformer pressure drop on-site test system and method |
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| CN201402287Y (en) * | 2009-04-03 | 2010-02-10 | 江苏省电力公司苏州供电公司 | Voltage drop detecting device of secondary circuit of voltage transformer |
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