CN103018573A - Field measurement system for dielectric loss value of crosslinked polyethylene power cable - Google Patents
Field measurement system for dielectric loss value of crosslinked polyethylene power cable Download PDFInfo
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- CN103018573A CN103018573A CN2012103005667A CN201210300566A CN103018573A CN 103018573 A CN103018573 A CN 103018573A CN 2012103005667 A CN2012103005667 A CN 2012103005667A CN 201210300566 A CN201210300566 A CN 201210300566A CN 103018573 A CN103018573 A CN 103018573A
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Abstract
The invention provides a field measurement system for a dielectric loss value of a crosslinked polyethylene power cable. The field measurement system comprises a resonant power supply, a standard capacitor, a first to-be-tested crosslinked polyethylene power cable, a first current transformer and a straight polarity monitoring unit, wherein the standard capacitor is connected with the resonant power supply; the first to-be-tested crosslinked polyethylene power cable is connected with the resonant power supply; the first current transformer is connected with the first to-be-tested crosslinked polyethylene power cable, and is used for measuring and outputting a low-voltage current signal of the first to-be-tested crosslinked polyethylene power cable; and the straight polarity monitoring unit is connected with the standard capacitor and the first current transformer respectively, measures a current signal output from the standard capacitor, receives the low-voltage current signal output from the first current transformer, and calculates the dielectric loss value of the first to-be-tested crosslinked polyethylene power cable at current frequency by a straight polarity method according to the current signal output from the standard capacitor and the low-voltage current signal. The field measurement system can implement field measurement of the dielectric loss value of the large-scale and large-capacity crosslinked polyethylene power cable.
Description
Technical field
The present invention relates to the dielectric loss value measuring technique, more particularly, relate to a kind of in-site measurement system of cross-inked polyethylene power cable dielectric loss value.
Background technology
Dielectric loss refers to the energy loss of insulating medium under the voltage effect, dielectric loss value (being called for short the dielectric loss value) is the parameter of characterized medium loss size, if the dielectric loss value is excessive, the dielectric temperature is raise, it is aging to impel material to occur, cause the dielectric insulation performance to reduce or forfeiture, cause thermal breakdown.Cross-inked polyethylene power cable is as the important component part of electrical power transmission system, the size of the dielectric loss value of cross-inked polyethylene power cable is directly connected to the serviceable life of cross-inked polyethylene power cable transmission line capability and cross-inked polyethylene power cable, and the dielectric loss value of therefore measuring cross-inked polyethylene power cable seems particularly important.
The classic method of measuring at present power equipment dielectric loss value mainly contains the Schering bridge method, current ratio is than type bridge method and M type dielectric testing device method, yet the operating voltage of the measuring method that these are traditional is general lower and examination varying capacity measuring equipment is less, be only suitable in the laboratory cross-inked polyethylene power cable of certain section finite length (such as 0 to 100 meter length) being carried out the measurement of dielectric loss value, carry out the in-site measurement of cross-inked polyethylene power cable dielectric loss value if adopt these traditional measuring methods, so for the cross-inked polyethylene power cable of several kilometers at scene even tens of kilometers, the examination varying capacity of measuring required experiment power supply capacity and measuring equipment will be very huge, its volume will be very huge also, be difficult to carry out on-the-spot enforcement.There is limitation in traditional dielectric loss value measurement method for the dielectric loss value of the jumbo cross-inked polyethylene power cable in scene is measured, and inapplicable.
Summary of the invention
In view of this, the embodiment of the invention provides a kind of in-site measurement system of cross-inked polyethylene power cable dielectric loss value, the problem of measuring with the dielectric loss value that solves traditional jumbo cross-inked polyethylene power cable in the inapplicable scene of dielectric loss value measurement method.
For achieving the above object, the embodiment of the invention provides following technical scheme:
A kind of in-site measurement system of cross-inked polyethylene power cable dielectric loss value comprises:
Resonant power;
The standard capacitance that links to each other with described resonant power;
The first cross-inked polyethylene power cable to be measured that links to each other with described resonant power;
Link to each other with the described first cross-inked polyethylene power cable to be measured, measure the low-tension current signal of described the first cross-inked polyethylene power cable to be measured and export the first current transformer of described low-tension current signal;
Link to each other with described the first current transformer with described standard capacitance respectively, measure the current signal of described standard capacitance output, and receive the low-tension current signal of described the first current transformer output, adopt positive connection just to connect monitoring means according to the current signal of described standard capacitance output and the dielectric loss value of described low-tension current calculated signals the described first cross-inked polyethylene power cable to be measured under current frequency.
Optionally, described system also comprises:
The second cross-inked polyethylene power cable to be measured that links to each other with described resonant power;
Link to each other with the described second cross-inked polyethylene power cable to be measured, measure the high-tension current signal of described the second cross-inked polyethylene power cable to be measured and export the second current transformer of described high-tension current signal;
Link to each other with described the second current transformer with the described monitoring means that just connecing respectively, receive described high-tension current signal, described high-tension current signal is converted to digital signal, send described digital signal to the described monitoring means that just connecing, in order to describedly just connecing the reversal connection monitoring means that monitoring means adopts opposition method to calculate the dielectric loss value of the described second cross-inked polyethylene power cable to be measured under current frequency according to current signal and the described digital signal of described standard capacitance output, described reversal connection monitoring means links to each other with the described monitoring means that just connecing by optical fiber.
Optionally, the described monitoring means that just connecing comprises:
Sample to being conveyed into the described current signal that is just connecing monitoring means, the current signal of sampling is converted to the analog to digital converter of digital signal.
Optionally, the described monitoring means that just connecing also comprises:
The current signal of described standard capacitance output is converted to the electric current of voltage signal to voltage conversion circuit;
Link to each other with described electric current to voltage conversion circuit, described electric current is transformed to the comparer of corresponding frequency waveform to the voltage signal of voltage conversion circuit conversion;
Respectively with described analog to digital converter, described electric current to voltage conversion circuit links to each other with described comparer, current signal according to described standard capacitance output, the voltage signal of described conversion and frequency values corresponding to described frequency waveshape, the processor that the described frequency values of foundation is regulated the sample rate of described analog to digital converter.
Optionally, the described monitoring means that just connecing links to each other with described the first current transformer by the low pressure shielding line, and described resonant power links to each other with the described first cross-inked polyethylene power cable to be measured with described standard capacitance by high-voltage connection.
Optionally, described reversal connection monitoring means links to each other with described the second current transformer by high-voltage shielding line, and described resonant power links to each other with the described second cross-inked polyethylene power cable to be measured by high-voltage connection;
Described reversal connection monitoring means links to each other with described high-voltage connection, and described monitoring means is arranged between described standard capacitance and the described resonant power.
Optionally, described system also comprises:
Link to each other with the described monitoring means that just connecing, the described dielectric loss value that is just connecing under the current frequency that monitoring means calculates is scaled dielectric loss value under the predeterminated frequency, and controls the described host computer that is just connecing the monitoring means duty;
The described dielectric loss value that the described dielectric loss value that is just connecing under the current frequency that monitoring means calculates is scaled under the predeterminated frequency comprises: with the ratio of current frequency and predeterminated frequency, multiply each other with the dielectric loss value under the described current frequency, described product is the dielectric loss value under the predeterminated frequency.。
The embodiment of the invention also provides a kind of in-site measurement system of cross-inked polyethylene power cable dielectric loss value, comprising:
Resonant power;
The standard capacitance that links to each other with described resonant power;
The first cross-inked polyethylene power cable to be measured that links to each other with described resonant power;
Link to each other with the described first cross-inked polyethylene power cable to be measured, measure the high-tension current signal of described the first cross-inked polyethylene power cable to be measured and export the first current transformer of described high-tension current signal;
Link to each other with described the first current transformer, receive described high-tension current signal, described high-tension current signal is converted to digital signal, export the reversal connection monitoring means of described digital signal;
Link to each other with described reversal connection monitoring means with described standard capacitance respectively, measure the current signal of described standard capacitance output, and the digital signal of the described reversal connection monitoring means output of reception, adopt opposition method just to connect monitoring means according to what the current signal of described standard capacitance output and described digital signal were calculated the dielectric loss value of the described first cross-inked polyethylene power cable to be measured under current frequency, the described monitoring means that just connecing links to each other with described reversal connection monitoring means by optical fiber.
Optionally, described system also comprises:
The second cross-inked polyethylene power cable to be measured that links to each other with described resonant power;
Link to each other with the described monitoring means that just connecing with described the second cross-inked polyethylene power cable respectively, measure the low-tension current signal of described the second cross-inked polyethylene power cable to be measured, described low-tension current signal sent to describedly just connecing monitoring means, so that the described monitoring means that just connecing adopts positive connection according to the current signal of described standard capacitance output and the second current transformer of the dielectric loss value of described low-tension current calculated signals the described second cross-inked polyethylene power cable to be measured under current frequency.
Optionally, the described monitoring means that just connecing comprises:
Sample to being conveyed into the described current signal that is just connecing monitoring means, the current signal of sampling is converted to the analog to digital converter of digital signal;
The current signal of described standard capacitance output is converted to the electric current of voltage signal to voltage conversion circuit;
Link to each other with described electric current to voltage conversion circuit, described electric current is transformed to the comparer of corresponding frequency waveform to the voltage signal of voltage conversion circuit conversion;
Link to each other with described electric current to voltage conversion circuit, described comparer and described analog to digital converter respectively, calculate voltage signal and the frequency values corresponding to described frequency waveform of the current signal of exporting with described standard capacitance, described conversion, the processor that the described frequency values of foundation is regulated the sample rate of described analog to digital converter.
Based on technique scheme, the in-site measurement system of the cross-inked polyethylene power cable dielectric loss value that the embodiment of the invention provides, by resonant power measuring system is powered, so that the working power of measuring system can satisfy the needs of in-site measurement cross-inked polyethylene power cable dielectric loss value; Adopt simultaneously positive connection, introduce standard capacitance, the first current transformer and just connecing monitoring means the dielectric loss value of the current frequency of the first cross-inked polyethylene power cable to be measured is measured, avoided the demand of the huge examination varying capacity of measuring equipment; The invention solves the problem of the dielectric loss value measurement of traditional jumbo cross-inked polyethylene power cable in the inapplicable scene of dielectric loss value measurement method, realized the in-site measurement of extensive jumbo cross-inked polyethylene power cable dielectric loss value.
Description of drawings
In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art, the below will do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art, apparently, accompanying drawing in the following describes only is some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain according to these accompanying drawings other accompanying drawing.
The structural representation of the in-site measurement system of the cross-inked polyethylene power cable dielectric loss value that Fig. 1 provides for the embodiment of the invention;
Another structural representation of the in-site measurement system of the cross-inked polyethylene power cable dielectric loss value that Fig. 2 provides for the embodiment of the invention;
Again another structural representation of the in-site measurement system of the cross-inked polyethylene power cable dielectric loss value that Fig. 3 provides for the embodiment of the invention;
The structural representation that just connects monitoring means that Fig. 4 provides for the embodiment of the invention;
An again structural representation of the in-site measurement system of the cross-inked polyethylene power cable dielectric loss value that Fig. 5 provides for the embodiment of the invention;
The again structural representation again of the in-site measurement system of the cross-inked polyethylene power cable dielectric loss value that Fig. 6 provides for the embodiment of the invention;
The in addition structural representation again of the in-site measurement system of the cross-inked polyethylene power cable dielectric loss value that Fig. 7 provides for the embodiment of the invention.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the invention, the technical scheme in the embodiment of the invention is clearly and completely described, obviously, described embodiment only is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills belong to the scope of protection of the invention not making the every other embodiment that obtains under the creative work prerequisite.
The structural representation of the in-site measurement system of the cross-inked polyethylene power cable dielectric loss value that Fig. 1 provides for the embodiment of the invention, with reference to Fig. 1, this system can comprise: resonant power 1, standard capacitance 2, the first cross-inked polyethylene power cable 3, the first current transformers 4 to be measured and just connecing monitoring means 5; Wherein, resonant power 1 links to each other with the first cross-inked polyethylene power cable 3 to be measured with standard capacitance 2 respectively, the first cross-inked polyethylene power cable 3 to be measured links to each other with the first current transformer 4, is just connecing detecting unit 5 and is linking to each other with the first current transformer 4 with standard capacitance 2 respectively.
The first cross-inked polyethylene power cable 3 to be measured need to carry out the object that the dielectric loss value is measured for the embodiment of the invention, the current signal of the end (being current input terminal) that the first cross-inked polyethylene power cable 3 to be measured links to each other with resonant power 1 is the high-tension current signal, and the current signal of the current output terminal of the first cross-inked polyethylene power cable 3 to be measured is the low-tension current signal after the dielectric loss; The dielectric loss value that the embodiment of the invention adopts positive connection to carry out the first cross-inked polyethylene power cable 3 to be measured is measured, therefore the first current transformer 4 can be connected to the current output terminal of the first cross-inked polyethylene power cable 3 to be measured, measure the low-tension current signal of the first cross-inked polyethylene power cable 3 to be measured, the first current transformer 4 sends the low-tension current signal that measures to and just connects monitoring means 5.
Just connecing monitoring means 5 links to each other with the first current transformer 4 with standard capacitance 2, the current signal of measurement standard electric capacity 2 outputs, and receive the low-tension current signal that the first current transformer 4 transmits, adopt positive connection according to the current signal of standard capacitance 2 outputs and the dielectric loss value of low-tension current calculated signals the first cross-inked polyethylene power cable 3 to be measured under current frequency of the first current transformer 4 transmission;
As shown in Figure 1, just connecing the current signal that monitoring means 5 can adopt 2 outputs of first interface measurement standard electric capacity, the second interface receives the low-tension current signal that the first current transformer 4 transmits.
It should be noted that just to connect monitoring means for adopting positive connection to carry out the entity apparatus that the dielectric loss value is measured, the technician who is engaged in the measurement of high voltage dielectric loss value all can know.
The in-site measurement system of the cross-inked polyethylene power cable dielectric loss value that the embodiment of the invention provides, by resonant power measuring system is powered, so that the working power of measuring system can satisfy the needs of in-site measurement cross-inked polyethylene power cable dielectric loss value; Adopt simultaneously positive connection, introduce standard capacitance, the first current transformer and just connecing monitoring means the dielectric loss value of the current frequency of the first cross-inked polyethylene power cable to be measured is measured, avoided the demand of the huge examination varying capacity of measuring equipment; The invention solves the problem of the dielectric loss value measurement of traditional jumbo cross-inked polyethylene power cable in the inapplicable scene of dielectric loss value measurement method, realized the in-site measurement of extensive jumbo cross-inked polyethylene power cable dielectric loss value.
Optionally, in the system shown in Figure 1, just connecing monitoring means 5 and linking to each other with the first current transformer 4 by the low pressure shielding line, resonant power 1 links to each other with the first cross-inked polyethylene power cable 3 to be measured with standard capacitance 2 by high-voltage connection.
The embodiment of the invention also can adopt positive connection in conjunction with the form of opposition method, carries out the in-site measurement of cross-inked polyethylene power cable dielectric loss value, measures when realizing many cross-inked polyethylene power cable dielectric loss values.Another structural representation of the in-site measurement system of the cross-inked polyethylene power cable dielectric loss value that Fig. 2 provides for the embodiment of the invention, in conjunction with illustrated in figures 1 and 2, system shown in Figure 2 is on the basis of system shown in Figure 1, can also comprise: the second cross-inked polyethylene power cable 6, the second current transformers 7 to be measured and reversal connection monitoring means 8; Wherein, the second cross-inked polyethylene power cable 6 to be measured links to each other with resonant power 1, the second current transformer 7 links to each other with the second cross-inked polyethylene power cable 6 to be measured, and reversal connection monitoring means 8 links to each other with the second current transformer 7 with the second cross-inked polyethylene power cable 6 to be measured respectively.
Another need to carry out the object that the dielectric loss value is measured to the second cross-inked polyethylene power cable 6 to be measured for the embodiment of the invention, similar to the first cross-inked polyethylene power cable to be measured 3, the current signal of the end (being current input terminal) that the second cross-inked polyethylene power cable 6 to be measured links to each other with resonant power 1 is the high-tension current signal, and the current signal of the current output terminal of the second cross-inked polyethylene power cable 6 to be measured is the low-tension current signal after the dielectric loss; The dielectric loss value that the embodiment of the invention adopts positive connection to carry out the first cross-inked polyethylene power cable 3 to be measured and the second cross-inked polyethylene power cable 6 to be measured in conjunction with the form of opposition method is measured, therefore adopt positive connection shown in Figure 1 to carry out on the basis of dielectric loss value measurement at the first cross-inked polyethylene power cable 3 to be measured, can make the second current transformer 7 be connected to the current input terminal of the second cross-inked polyethylene power cable 6 to be measured, measure the high-tension current signal of the second cross-inked polyethylene power cable 6 to be measured, the second current transformer 7 sends the high-tension current signal that measures to reversal connection monitoring means 8.
Reversal connection monitoring means 8 and the second current transformer 7 with just connect monitoring means 5 and link to each other, wherein, reversal connection monitoring means 8 with just connecing monitoring means 5 and communicating by optical fiber, the data that realize just connecing 8 of monitoring means 5 and reversal connection monitoring means synchronously and data gather, reversal connection monitoring means 8 receives the high-tension current signal that the second current transformer 7 is measured, this high-tension current signal is converted to digital signal, this digital signal given by optical fiber transmission just connect monitoring means 5, adopt opposition methods to calculate the dielectric loss value of the second cross-inked polyethylene power cable 6 to be measured under current frequency according to the digital signal that current signal and the reversal connection monitoring means 8 of standard capacitance 2 outputs transmits so that just connecing monitoring means 5.
Just connecing monitoring means 5 in embodiments of the present invention except adopting positive connection to carry out the dielectric value calculating of the first cross-inked polyethylene power cable 3 to be measured, the dielectric value that also adopts opposition method to carry out the second cross-inked polyethylene power cable 6 to be measured is calculated, therefore just connect monitoring means 5 after the digital signal that receives 7 transmission of the second current transformer, beginning the calculating of the dielectric loss value of the second cross-inked polyethylene power cable 6 to be measured under current frequency.
It should be noted that the reversal connection monitoring means is just connecing the entity apparatus that monitoring means employing opposition method is carried out the measurement of dielectric loss value for cooperating, the technician who is engaged in the measurement of high voltage dielectric loss value all can know.
System shown in Figure 2 can simultaneously to the measurement of carrying out the dielectric loss value of many cross-inked polyethylene power cables, improve the efficient of cross-inked polyethylene power cable dielectric loss value in-site measurement in conjunction with positive connection and opposition method.
Optionally, reversal connection monitoring means 8 links to each other with the second current transformer 7 by high-voltage shielding line, and resonant power 1 links to each other with the second cross-inked polyethylene power cable 6 to be measured by high-voltage connection.
Optionally, reversal connection monitoring means 8 can be arranged between standard capacitance 2 and the resonant power 1, be connected on the high-voltage connection, as shown in Figure 3, again another structural representation of the in-site measurement system of the cross-inked polyethylene power cable dielectric loss value that Fig. 3 provides for the embodiment of the invention.
Resonant power is multiplex in the withstand voltage test of on-site crosslinked polyethylene power cable series resonance at present, therefore the in-site measurement system of cross-inked polyethylene power cable dielectric loss value of the present invention can combine with general cross-inked polyethylene power cable series resonance alternating-current voltage resistance test device, when carrying out cross-inked polyethylene power cable series resonance AC voltage withstand test, the resonant power of employing AC voltage withstand test carries out the in-site measurement of cross-inked polyethylene power cable dielectric loss value, yet the frequency range of at present on-site crosslinked polyethylene power cable series resonance withstand voltage test is generally 30 to 300HZ(hertz), there is the part of the frequency range that exceeds the measurement of cross-inked polyethylene power cable dielectric loss value in this scope, has the situation that is unfavorable for cross-inked polyethylene power cable dielectric loss value in-site measurement.
Based on above-mentioned situation, on the basis of the in-site measurement system of the cross-inked polyethylene power cable dielectric loss value that the embodiment of the invention provides, the embodiment of the invention provides an AD(simulating signal to digital signal) sample rate adjustable just connect monitoring means, to be implemented in the in-site measurement of the cross-inked polyethylene power cable dielectric loss value in the high-frequency range (such as 30HZ to 300HZ).
The structural representation that just connects monitoring means that Fig. 4 provides for the embodiment of the invention, with reference to Fig. 4, just connecing monitoring means can comprise:
Sample to being conveyed into the current signal that just connects monitoring means, the current signal of sampling is converted to the analog to digital converter 100 of digital signal;
Mostly be simulating signal owing to just connecing the current signal of monitoring means access, and usually adopt at present digital form to calculate the dielectric loss value, therefore just connecing the device that one of existence can be carried out the AD sampling in the monitoring means, the device of AD sampling is analog to digital converter 100 in the embodiment of the invention; Analog to digital converter 100 is converted to digital signal with the current signal of sampling, carries out follow-up dielectric loss value calculating in order to just connecing monitoring means.
The current signal of standard capacitance output is converted to the electric current of voltage signal to voltage conversion circuit 200;
Link to each other with electric current to voltage conversion circuit 200, electric current is transformed to the comparer 300 of corresponding frequency waveform to the voltage signal of voltage conversion circuit 200 conversions;
Respectively with analog to digital converter 100, electric current to voltage conversion circuit 200 links to each other with comparer 300, current signal according to described standard capacitance output, the voltage signal of described conversion and frequency values corresponding to described frequency waveshape, the processor 400 that the described frequency values of foundation is regulated the sample rate of described analog to digital converter.
Concrete being applied as: when just connecing the rising of monitoring means external resonant voltage, just connect detecting unit and obtaining electric current by standard capacitance, then by its inner I-V change-over circuit (electric current is to voltage conversion circuit), current signal is converted to voltage signal, voltage signal draws its frequency waveform by comparer, just connecing the processor real-time sampling frequency waveform of monitoring means inside, voltage signal after the conversion and the current signal of standard capacitance, calculate and the frequency waveform, then voltage signal after the conversion and frequency values corresponding to the current signal of standard capacitance regulate the AD(analog to digital converter in real time according to the frequency values that calculates) sample rate.
The embodiment of the invention has better realized the in-site measurement of the cross-inked polyethylene power cable dielectric loss value under the high-frequency range by keeping best AD sample rate to follow the tracks of and adapting to the signal that is sampled under the high-frequency range (such as 30HZ to 300Hz).
An again structural representation of the in-site measurement system of the cross-inked polyethylene power cable dielectric loss value that Fig. 5 provides for the embodiment of the invention, in conjunction with Fig. 2 and shown in Figure 5, Fig. 5 also comprises on the basis of system shown in Figure 2: host computer 9.
Host computer 9 with just connect monitoring means 5 and link to each other, be scaled dielectric loss value under the predeterminated frequency with just connecing dielectric loss value under the current frequency that monitoring means 5 calculates, and control is just connecing the duty of monitoring means 5.
National standard all is to compare in the dielectric loss value of carrying out under the frequency of 50HZ between cross-inked polyethylene power cable at present, and the present invention carries out the dielectric loss value of cross-inked polyethylene power cable to measure under high-frequency range, measured dielectric loss value may be the dielectric loss value under 30HZ to the 300Hz alien frequencies, in order better to compare in the dielectric loss value of carrying out under the frequency of national standard 50HZ between cross-inked polyethylene power cable, therefore after the cross-inked polyethylene power cable dielectric loss value that just connects under the current frequency of monitoring means 5 calculating, host computer 9 can be scaled the cross-inked polyethylene power cable dielectric loss value corresponding with the 50HZ frequency with just connecing the dielectric loss value that monitoring means 5 calculates, be implemented between the cross-inked polyethylene power cable under the national standard the dielectric loss value relatively.
Obviously, the embodiment of the invention also can be according to actual needs predeterminated frequency value, is scaled dielectric loss value under the predeterminated frequency with just connecing dielectric loss value that monitoring means 5 calculates.
For better explanation embodiment of the invention host computer 9 will just connect the implementation that dielectric loss value under the current frequency that monitoring means 5 calculates is scaled the dielectric loss value under the predeterminated frequency, describe below in conjunction with following expression formula.
Suppose that the dielectric loss value that measures under current frequency f x is tgx, according to power relation, the dielectric loss value also can be equivalent to active power divided by reactive power, so
Tgx=Ir*U/Ic*U=Ir/Ic, wherein U is cross-inked polyethylene power cable voltage, and Ir is the resistor current of cross-inked polyethylene power cable, and Ic is the capacitance current of cross-inked polyethylene power cable;
Again because Ir=U/Rx, Ic=2* π * fx*C*U, wherein Rx is the resistance of cross-inked polyethylene power cable, C is the equivalent capacity of cross-inked polyethylene power cable;
So tgx=1/ (2* π * fx*C*U*Rx);
Suppose that the cross-inked polyethylene power cable dielectric loss value that measures is tgx1 under 50Hz, then
tgx1=1/(2*π*50*C*U*Rx)；
So tgx1=tgx*fx/50;
As seen, host computer 9 will just connect the dielectric loss value that the dielectric loss value under the current frequency that monitoring means 5 calculates is scaled under the 50HZ frequency and comprise: with the ratio of current frequency and 50HZ, multiply each other with the dielectric loss value under the described current frequency, the gained product is the dielectric loss value under the 50HZ frequency; Corresponding, if will be scaled dielectric loss value under the predeterminated frequency, only need the ratio with current frequency and predeterminated frequency, multiply each other with dielectric loss value under the described current frequency, the gained product is the dielectric loss value under the predeterminated frequency.
In addition, host computer 9 also can be controlled the duty that is just connecing monitoring means 5, aligns work such as connecing monitoring means 5 measurement current signals, calculating dielectric loss value and triggers.
Obviously, also can comprise above-mentioned host computer in the system shown in Figure 1.
The embodiment of the invention is scaled the dielectric loss value corresponding with predeterminated frequency by the cross-inked polyethylene power cable dielectric loss value that host computer will just connect under the measured current frequency of monitoring means, can realize that the dielectric loss value between a plurality of cross-inked polyethylene power cables under the same frequency compares, for the subsequent treatment after the dielectric loss value of calculating cross-inked polyethylene power cable has been carried out the basis.
The embodiment of the invention also can adopt separately opposition method to carry out the in-site measurement of cross-inked polyethylene power cable dielectric loss value, and the system that the independent employing opposition method that the below provides the embodiment of the invention is carried out the in-site measurement of cross-inked polyethylene power cable dielectric loss value describes.
The again structural representation again of the in-site measurement system of the cross-inked polyethylene power cable dielectric loss value that Fig. 6 provides for the embodiment of the invention, with reference to Fig. 6, this system can comprise:
The standard capacitance 2 that links to each other with resonant power 1;
The first cross-inked polyethylene power cable 3 to be measured that links to each other with resonant power 1;
Link to each other with the first cross-inked polyethylene power cable 3 to be measured, measure the high-tension current signal of the first cross-inked polyethylene power cable 3 to be measured and export the first current transformer 4 of described high-tension current signal;
Link to each other with the first current transformer 4, receive described high-tension current signal, described high-tension current signal is converted to digital signal, export the reversal connection monitoring means 5 of described digital signal;
Link to each other with reversal connection monitoring means 5 with standard capacitance 2 respectively, the current signal of measurement standard electric capacity 2 outputs, and the digital signal of reception reversal connection monitoring means 5 outputs, adopt opposition method just to connect monitoring means 6 according to what the current signal of described standard capacitance output and described digital signal were calculated the dielectric loss value of the first cross-inked polyethylene power cable 3 to be measured under current frequency, wherein, just connecing monitoring means 6 and reversal connection monitoring means 5 and adopting optical fiber to link to each other, by optical fiber carry out between the two data synchronously with gather.
It should be noted that, the measuring system of above introducing and system shown in Figure 1 all are by the current signal of measurement standard electric capacity output and the current signal of cross-inked polyethylene power cable to be measured, calculate the dielectric loss value under the current frequency of cross-inked polyethylene power cable to be measured by just connecing monitoring means, so system shown in Figure 6 and system shown in Figure 1 should be thought and belong to an inventive concept.
The in-site measurement system of the cross-inked polyethylene power cable dielectric loss value that the embodiment of the invention provides, by resonant power measuring system is powered, so that the working power of measuring system can satisfy the needs of in-site measurement cross-inked polyethylene power cable dielectric loss value; Adopt simultaneously opposition method, introduce standard capacitance, the first current transformer, reversal connection monitoring means and just connecing monitoring means the dielectric loss value of the first cross-inked polyethylene power cable to be measured under current frequency measured, avoided the demand of the huge examination varying capacity of measuring equipment; The invention solves the problem of the dielectric loss value measurement of traditional jumbo cross-inked polyethylene power cable in the inapplicable scene of dielectric loss value measurement method, realized the in-site measurement of extensive jumbo cross-inked polyethylene power cable dielectric loss value.
Similar with system shown in Figure 2, the embodiment of the invention also can realize in conjunction with positive connection the in-site measurement of a plurality of cross-inked polyethylene power cable dielectric loss values except the in-site measurement of the dielectric loss value of independent employing opposition method realization cross-inked polyethylene power cable.The in addition structural representation again of the in-site measurement system of the cross-inked polyethylene power cable dielectric loss value that Fig. 7 provides for the embodiment of the invention, in conjunction with Fig. 6 and shown in Figure 7, system shown in Figure 7 can also comprise at the basis of system shown in Figure 6 row:
The second cross-inked polyethylene power cable 7 to be measured of 1 links to each other with resonant power;
Respectively with the second cross-inked polyethylene power cable 7 with just connect monitoring means 6 and link to each other, measure the low-tension current signal of the second cross-inked polyethylene power cable 7 to be measured, described low-tension current signal is sent to the second current transformer 8 that just connects monitoring means 6.
The second current transformer 8 sends described low-tension current signal to and just connects monitoring means 6, can adopt positive connection according to current signal and the dielectric loss value of described low-tension current calculated signals the second cross-inked polyethylene power cable 7 to be measured under current frequency of standard capacitance 2 outputs so that just connecing monitoring means 6.
Need to prove, the structure that just connects monitoring means in Fig. 6 and the system shown in Figure 7 can be as shown in Figure 4, also can comprise host computer in Fig. 6 and the system shown in Figure 7, the corresponding setting that just connects monitoring means and host computer does not repeat them here, can be with reference to explanation shown in Figure 4.There are a lot of similar parts in Fig. 6 and system shown in Figure 7 with system illustrated in figures 1 and 2, can mutually carry out reference to this, repeat no more herein.
The in-site measurement system of cross-inked polyethylene power cable dielectric loss value provided by the present invention powers to measuring system by resonant power, so that the working power of measuring system can satisfy the needs of in-site measurement cross-inked polyethylene power cable dielectric loss value; Introduce simultaneously the current signal of standard capacitance, collection standard capacitance and cross-inked polyethylene power cable to be measured, realize the in-site measurement of the dielectric loss value of cross-inked polyethylene power cable to be measured under current frequency by just connecing monitoring means, avoided the demand of the huge examination varying capacity of measuring equipment; The invention solves the problem of the dielectric loss value measurement of traditional jumbo cross-inked polyethylene power cable in the inapplicable scene of dielectric loss value measurement method, realized the in-site measurement of extensive jumbo cross-inked polyethylene power cable dielectric loss value.
To the above-mentioned explanation of the disclosed embodiments, make this area professional and technical personnel can realize or use the present invention.Multiple modification to these embodiment will be apparent concerning those skilled in the art, and General Principle as defined herein can in the situation that does not break away from the spirit or scope of the present invention, realize in other embodiments.Therefore, the present invention will can not be restricted to these embodiment shown in this article, but will meet the widest scope consistent with principle disclosed herein and features of novelty.
Claims (10)
1. the in-site measurement system of a cross-inked polyethylene power cable dielectric loss value is characterized in that, comprising:
Resonant power;
The standard capacitance that links to each other with described resonant power;
The first cross-inked polyethylene power cable to be measured that links to each other with described resonant power;
Link to each other with the described first cross-inked polyethylene power cable to be measured, measure the low-tension current signal of described the first cross-inked polyethylene power cable to be measured and export the first current transformer of described low-tension current signal;
Link to each other with described the first current transformer with described standard capacitance respectively, measure the current signal of described standard capacitance output, and receive the low-tension current signal of described the first current transformer output, adopt positive connection just to connect monitoring means according to the current signal of described standard capacitance output and the dielectric loss value of described low-tension current calculated signals the described first cross-inked polyethylene power cable to be measured under current frequency.
2. system according to claim 1 is characterized in that, also comprises:
The second cross-inked polyethylene power cable to be measured that links to each other with described resonant power;
Link to each other with the described second cross-inked polyethylene power cable to be measured, measure the high-tension current signal of described the second cross-inked polyethylene power cable to be measured and export the second current transformer of described high-tension current signal;
Link to each other with described the second current transformer with the described monitoring means that just connecing respectively, receive described high-tension current signal, described high-tension current signal is converted to digital signal, send described digital signal to the described monitoring means that just connecing, in order to describedly just connecing the reversal connection monitoring means that monitoring means adopts opposition method to calculate the dielectric loss value of the described second cross-inked polyethylene power cable to be measured under current frequency according to current signal and the described digital signal of described standard capacitance output, described reversal connection monitoring means links to each other with the described monitoring means that just connecing by optical fiber.
3. system according to claim 1 and 2 is characterized in that, the described monitoring means that just connecing comprises:
Sample to being conveyed into the described current signal that is just connecing monitoring means, the current signal of sampling is converted to the analog to digital converter of digital signal.
4. system according to claim 3 is characterized in that, the described monitoring means that just connecing also comprises:
The current signal of described standard capacitance output is converted to the electric current of voltage signal to voltage conversion circuit;
Link to each other with described electric current to voltage conversion circuit, described electric current is transformed to the comparer of corresponding frequency waveform to the voltage signal of voltage conversion circuit conversion;
Respectively with described analog to digital converter, described electric current to voltage conversion circuit links to each other with described comparer, current signal according to described standard capacitance output, the voltage signal of described conversion and frequency values corresponding to described frequency waveshape, the processor that the described frequency values of foundation is regulated the sample rate of described analog to digital converter.
5. system according to claim 1, it is characterized in that, the described monitoring means that just connecing links to each other with described the first current transformer by the low pressure shielding line, and described resonant power links to each other with the described first cross-inked polyethylene power cable to be measured with described standard capacitance by high-voltage connection.
6. system according to claim 2 is characterized in that, described reversal connection monitoring means links to each other with described the second current transformer by high-voltage shielding line, and described resonant power links to each other with the described second cross-inked polyethylene power cable to be measured by high-voltage connection;
Described reversal connection monitoring means links to each other with described high-voltage connection, and described monitoring means is arranged between described standard capacitance and the described resonant power.
7. according to claim 1,2,4,5 or 6 described systems, it is characterized in that, also comprise:
Link to each other with the described monitoring means that just connecing, the described dielectric loss value that is just connecing under the current frequency that monitoring means calculates is scaled dielectric loss value under the predeterminated frequency, and controls the described host computer that is just connecing the monitoring means duty;
The described dielectric loss value that the described dielectric loss value that is just connecing under the current frequency that monitoring means calculates is scaled under the predeterminated frequency comprises: with the ratio of current frequency and predeterminated frequency, multiply each other with the dielectric loss value under the described current frequency, described product is the dielectric loss value under the predeterminated frequency.
8. the in-site measurement system of a cross-inked polyethylene power cable dielectric loss value is characterized in that, comprising:
Resonant power;
The standard capacitance that links to each other with described resonant power;
The first cross-inked polyethylene power cable to be measured that links to each other with described resonant power;
Link to each other with the described first cross-inked polyethylene power cable to be measured, measure the high-tension current signal of described the first cross-inked polyethylene power cable to be measured and export the first current transformer of described high-tension current signal;
Link to each other with described the first current transformer, receive described high-tension current signal, described high-tension current signal is converted to digital signal, export the reversal connection monitoring means of described digital signal;
Link to each other with described reversal connection monitoring means with described standard capacitance respectively, measure the current signal of described standard capacitance output, and the digital signal of the described reversal connection monitoring means output of reception, adopt opposition method just to connect monitoring means according to what the current signal of described standard capacitance output and described digital signal were calculated the dielectric loss value of the described first cross-inked polyethylene power cable to be measured under current frequency, the described monitoring means that just connecing links to each other with described reversal connection monitoring means by optical fiber.
9. system according to claim 8 is characterized in that, also comprises:
The second cross-inked polyethylene power cable to be measured that links to each other with described resonant power;
Link to each other with the described monitoring means that just connecing with described the second cross-inked polyethylene power cable respectively, measure the low-tension current signal of described the second cross-inked polyethylene power cable to be measured, described low-tension current signal sent to describedly just connecing monitoring means, so that the described monitoring means that just connecing adopts positive connection according to the current signal of described standard capacitance output and the second current transformer of the dielectric loss value of described low-tension current calculated signals the described second cross-inked polyethylene power cable to be measured under current frequency.
10. according to claim 8 or 9 described systems, it is characterized in that the described monitoring means that just connecing comprises:
Sample to being conveyed into the described current signal that is just connecing monitoring means, the current signal of sampling is converted to the analog to digital converter of digital signal;
The current signal of described standard capacitance output is converted to the electric current of voltage signal to voltage conversion circuit;
Link to each other with described electric current to voltage conversion circuit, described electric current is transformed to the comparer of corresponding frequency waveform to the voltage signal of voltage conversion circuit conversion;
Link to each other with described electric current to voltage conversion circuit, described comparer and described analog to digital converter respectively, calculate voltage signal and the frequency values corresponding to described frequency waveform of the current signal of exporting with described standard capacitance, described conversion, the processor that the described frequency values of foundation is regulated the sample rate of described analog to digital converter.
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| CN201210300566.7A CN103018573B (en) | 2012-08-22 | 2012-08-22 | Field measurement system for dielectric loss value of crosslinked polyethylene power cable |
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