Summary of the invention
The technical problem to be solved in the present invention is to provide a kind of pole tower ground resistance measurement method, and it can improve electric current, the voltage measurement accuracy of pincerlike meter, and then improves the degree of accuracy that pincerlike meter measures pole tower ground resistance.
For solving the problems of the technologies described above, the invention provides technical scheme as follows:
A kind of pole tower ground resistance measurement method, first carry out self-inspection to pincerlike meter, then utilize the pincerlike meter after self-inspection to measure, wherein, described pincerlike meter comprises voltage transformer (VT) summation current transformer;
Describedly self-inspection carried out to pincerlike meter comprise electric current self-inspection and voltage self-inspection:
Described electric current self-inspection is: by the jaw place of first wire through described current transformer, now, close described voltage transformer (VT), the current signal utilizing the AC constant-current source module of pincerlike meter inside to produce many grades of amplitudes different flows through described first wire, described current transformer is utilized to obtain the measured value of current signal, the size of current that the actual current produced by more described AC constant-current source module and described current transformer are recorded, recycling method of interpolation obtains the curved line relation of electric current actual value and measured value, for the actual value of the calculating current size when follow-up measurement,
Described voltage self-inspection is: by the jaw place of second wire through described voltage transformer (VT), and keep described second wire two ends open circuit, utilize described voltage transformer (VT) that voltage signals different for many grades of amplitudes is induced to tower grounding downlead and described second wire, the voltage at described second wire two ends and the voltage of tower grounding downlead, by more described voltage transformer (VT) former end input voltage and described second wire both end voltage size, recycling method of interpolation obtains the curved line relation of voltage actual value and measured value, for the actual value of the calculating voltage size when follow-up measurement.
Further, described first wire and second wire are same wires.
Further, described pincerlike meter comprises MCU module, signal generator, bandpass filter and phase measurement module, the control signal output terminal of described MCU module is connected with the signal input part of described signal generator, the output terminal of described signal generator is connected with the input end of described bandpass filter, the input end of described bandpass filter is all connected with the input end of described phase measurement module with output terminal, and the output terminal of described phase measurement module accesses the data signal input of described MCU module;
Describedly self-inspection carried out to pincerlike meter also comprise Selecting phasing self-inspection:
Described Selecting phasing self-inspection is: under the control of described MCU module, described signal generator launches the electric signal of certain frequency through described bandpass filter, described phase measurement module measures the phase place before and after filtering, and transfer to described MCU module, the phase differential before and after described bandpass filter is gone out in described MCU module internal calculation
If this phase differential is less than certain threshold value, then adopt the signal of this frequency during follow-up measurement of Grounding Resistance, otherwise the advanced or delayed different situations according to phase place, change signal generator transmission frequency, till described phase differential meets the demands.
Further, near the center frequency point of described bandpass filter, frequency signal is selected in described Selecting phasing self-inspection.
The present invention has following beneficial effect:
When actual measurement, first, by the jaw place of a wire through current transformer, and described voltage transformer (VT) is closed, the AC constant-current source module of pincerlike meter inside is utilized to produce the signal identical with survey frequency and flow into this wire, utilize mutual inductor to gather this signal, then, change current amplitude size, many surveys several groups of data, obtain the relation of actual input value and line voltage distribution influence value, for the actual value of the calculating current size when follow-up measurement, realize electric current self-inspection; Then, by an inc wire in two ends, through voltage transformer (VT) jaw place, different voltage signals is applied to voltage transformer (VT), and detect the voltage difference at wire two ends, obtain the relation of actual input value and line voltage distribution influence value, for the actual value of the calculating voltage size when follow-up measurement, realize voltage self-inspection; By electric current self-inspection and voltage self-inspection, improve the measuring accuracy of electric current, voltage, and then improve the precision of surveyed stake resistance.
Embodiment
For making the technical problem to be solved in the present invention, technical scheme and advantage clearly, be described in detail below in conjunction with the accompanying drawings and the specific embodiments.
As shown in Figure 1-2, the invention provides a kind of pole tower ground resistance measurement method, first carry out self-inspection to pincerlike meter 24, then utilize the pincerlike meter 24 after self-inspection to measure, wherein, pincerlike meter 24 comprises voltage transformer (VT) 21 summation current transformer 22;
Self-inspection is carried out to pincerlike meter 24 and comprises electric current self-inspection 11 and voltage self-inspection 12:
Electric current self-inspection 11 is: by the jaw place of first wire through described current transformer 22, now, close described voltage transformer (VT) 21, the current signal utilizing the AC constant-current source module of pincerlike meter 24 inside to produce many grades of amplitudes different flows through first wire, current transformer 22 is utilized to obtain the measured value of current signal, the size of current that the actual current produced by more described AC constant-current source module and described current transformer 22 are recorded, recycling method of interpolation obtains the curved line relation of electric current actual value and measured value, for the actual value of the calculating current size when follow-up measurement.
Voltage self-inspection 2 is: by the jaw place of second wire through voltage transformer (VT) 21, and keep second wire two ends open circuit, utilize voltage transformer (VT) 21 that voltage signals different for many grades of amplitudes is induced to tower grounding downlead and second wire, the voltage at second wire two ends and the voltage of tower grounding downlead, by the former end input voltage of comparative voltage mutual inductor 21 and second wire both end voltage size, recycling method of interpolation obtains the curved line relation of voltage actual value and measured value, for the actual value of the calculating voltage size when follow-up measurement.
General, split-core type meter type earth resistance tester Bian open type mutual inductor is measured, and comprise voltage transformer (VT) 21 summation current transformer 22, in this open-core transformer, faradic link has been disconnected, namely responding to magnetic core is not an airtight entirety, and at gap place, magnetic circuit efficiency reduces.Owing to being difficult to accomplish to fit completely when measuring, so have certain influence in inductive effects and precision, thus produce measuring error.
Poor and the transformer core of consistance due to voltage transformer (VT) 21 closes the difference of degree, even apply identical voltage at the primary side of voltage transformer (VT) 21, the magnitude of voltage then induced on the downlead of electric power line pole tower is also different, and this voltage error can have a strong impact on the precision that powerline pole tower ground resistance is measured.
Due to the impact of the environmental factors such as above-mentioned same reason and humiture, the data of current transformer 22 retaking of a year or grade accurately can not react the situation of electric current in power transmission pole tower ground down lead.
When utilizing method provided by the present invention to measure, first, by the jaw place of a wire through current transformer 22, and close voltage transformer (VT) 21, the AC constant-current source module of pincerlike meter inside is utilized to produce the signal identical with survey frequency and flow into this wire, mutual inductor is utilized to gather this signal, then, change current amplitude size, many surveys several groups of data, obtain the relation of actual input value and line voltage distribution influence value, for the actual value of the calculating current size when follow-up measurement, realize electric current self-inspection 11; Then, by an inc wire in two ends, through voltage transformer (VT) 21 jaw place, different voltage signals is applied to voltage transformer (VT) 21, and detect the voltage difference at wire two ends, obtain the relation of actual input value and line voltage distribution influence value, for the actual value of the calculating voltage size when follow-up measurement, realize voltage self-inspection 12; By electric current self-inspection 11 and voltage self-inspection 12, improve the measuring accuracy of electric current, voltage, and then improve the precision of surveyed stake resistance.In real work, first wire and second wire preferably same wire.
In addition, as shown in Figure 3, pincerlike meter comprises MCU module 31, signal generator 32, bandpass filter 33 and phase measurement module 34, the control signal output terminal of MCU module 31 is connected with the signal input part of signal generator 32, the output terminal of signal generator 32 is connected with the input end of bandpass filter 33, the input end of bandpass filter 33 is all connected with the input end of phase measurement module 34 with output terminal, the data signal input of the output terminal access MCU module 31 of phase measurement module 34;
Electric power line pole tower ground loop is not purely resistive, if directly adopt the method measurement of Grounding Resistance resistance of voltage and current ratio, it sends voltage and returns to survey between electric current exists certain phase differential, if ignore this index, then actual measured value is the impedance ground value of electric power line pole tower but not grounding resistance, and the reality affecting electric power line pole tower ground connection performance is pole tower ground resistance value but not resistance value.
So, as shown in Figure 1, for making result more accurate, self-inspection being carried out to pincerlike meter and also comprises Selecting phasing self-inspection 13:
Selecting phasing self-inspection 3 is: under the control of MCU module 31, signal generator 32 launches the electric signal of certain frequency through bandpass filter 33, phase measurement module 34 measures the phase place before and after filtering, and transfer to MCU module 31, the phase differential before and after bandpass filter 33 is gone out in MCU module 31 internal calculation, if this phase differential is less than certain threshold value, then adopt the signal of this frequency during follow-up measurement of Grounding Resistance, otherwise, advanced or the delayed different situations according to phase place, change signal generator 32 transmission frequency, till described phase differential meets the demands.
Compared with prior art, usually adopt bandpass filter 33 to obtain signal when signal transacting in current pincerlike meter 24 earth resistance tester, because bandpass filter 33 is by the impact of the factors such as environment, the center frequency point of its filtering also can change, if do not taked corresponding measure, measuring-signal is likely decayed to some extent on the one hand, larger phase error can be produced on the other hand, thus produce more serious measuring error, the present invention adopts phase filtering, avoiding environment causes the skew of bandpass filter 33 center frequency points and the non-resistive impact on measurement result of ground loop itself to make measurement result closer to actual resistance.
In order to make Selecting phasing process of self-test carry out faster, preferentially near the center frequency point of bandpass filter 33, select frequency signal.。
Finally, as shown in Figure 1, when having carried out electric current self-inspection, voltage self-inspection, Selecting phasing self-inspection, next just detection 14 can have been carried out to stake resistance.
Beneficial effect of the present invention is as follows:
1, when actual measurement, first, by an inc wire in two ends, through voltage transformer (VT), different voltage signals is applied to voltage transformer (VT), obtain the relation of actual input value and line voltage distribution influence value, realize voltage self-inspection; Then, by a wire through current transformer, the AC constant-current source module of signal circuit inside produces the signal identical with survey frequency and flows into this wire and utilizes mutual inductor to gather this signal, obtain the relation of actual input value and line voltage distribution influence value, realize electric current self-inspection, by voltage self-inspection and electric current self-inspection, improve voltage, the measuring accuracy of electric current, and then the precision that improve surveyed stake resistance.
2, compared with prior art, the present invention adopts phase filtering, avoids environment and causes the skew of bandpass filter center frequency points and the non-resistive impact on measurement result of ground loop itself, make measurement result closer to actual resistance.
The above is the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the prerequisite not departing from principle of the present invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.