1. An electrode pole difference eliminating system for measuring an electric field of an electromagnetic prospecting method, comprising: the device comprises an electrode module, an electrode charge extraction module, an instrument amplification module and an electrode charge compensation module;

the electrode module is used for coupling electric field signals and forming an electrode double electric layer;

the electrode charge extraction module is used for extracting the charges transferred by the double electric layers of the electrodes;

the meter amplification module is used for obtaining the charge amount of the electrode double electric layer based on the extraction of the charges transferred by the electrode double electric layer;

and the electrode charge compensation module is used for reversely compensating the equivalent charge into the electrode module through a capacitor according to the charge quantity of the double electric layers of the electrodes so as to finish electrode range elimination.

2. The system for eliminating electrode range difference for measuring an electromagnetic prospecting electric field according to claim 1, wherein the circuit model corresponding to the electrode module comprises an electrode grounding resistance (Rp), an electrode double-layer capacitance (Cp), an electrode double-layer capacitance range signal source (ep), a ground electric field signal source (E);

one end of the earth electric field signal source (E) is respectively connected with the electrode grounding resistance (Rp) and the electrode double-layer capacitance range difference signal source (ep), and the other end is grounded; the electrode double layer capacitance range signal source (ep) is connected in series with the electrode double layer capacitance (Cp); the electrode double layer capacitance (Cp) is connected to the electrode ground resistance (Rp); the electrode ground resistance (Rp) and the electrode double layer capacitance (Cp) are both connected to the electrode charge extraction module.

3. The system of claim 1, wherein the electrode charge extraction module comprises an electrode charge extraction capacitance (Cc); and the electrode charge extraction capacitor (Cc) is respectively connected with the instrument amplification module, the electrode charge compensation module and the electrode module.

4. The system for eliminating electrode range for electromagnetic prospecting electric field measurements of claim 3, characterized in that said instrument amplification module comprises a first amplifier (U1), a second amplifier (U2), a third amplifier (U3), a first resistor (R1), a second resistor (R2), a third resistor (R3), a fourth resistor (R4), a fifth resistor (R5), a sixth resistor (R6), a seventh resistor (R7);

the positive input ends of the first amplifier (U1) and the second amplifier (U2) are respectively connected with two ends of the electrode charge extraction capacitor (Cc);

the inverting input end of the first amplifier (U1) is respectively connected with the first resistor (R1) and the second resistor (R2); the output end of the first amplifier (U1) is respectively connected with the first resistor (R1) and the fourth resistor (R4);

the inverting input end of the second amplifier (U2) is respectively connected with the second resistor (R2) and the third resistor (R3); the output end of the second amplifier (U2) is respectively connected with the third resistor (R3) and the sixth resistor (R6);

the inverting input end of the third amplifier (U3) is respectively connected with the fourth resistor (R4) and the fifth resistor (R5); the positive input end of the third amplifier (U3) is respectively connected with the sixth resistor (R6) and the seventh resistor (R7); the output end of the third amplifier (U3) is respectively connected with the fifth resistor (R5) and the electrode charge compensation module;

the seventh resistor (R7) is connected to ground.

5. The system of claim 4, wherein the instrumentation amplification module employs a low noise amplifier.

6. The system for electrode pole difference elimination for electromagnetic prospecting electric field measurements according to claim 4, characterized in that said electrode charge compensation module comprises a fourth amplifier (U4), an eighth resistance (Rpi), a capacitance (Cpi);

the inverting input end of the fourth amplifier (U4) is respectively connected with the eighth resistor (Rpi) and the capacitor (Cpi); the output of said fourth amplifier (U4) being connected to said capacitor (Cpi) and said electrode charge extraction capacitor (Cc); a positive input of the fourth amplifier (U4) is connected to ground;

the eighth resistor (Rpi) is connected to the output of the third amplifier (U3).

7. The system of claim 6, wherein the electrode charge compensation module employs a low noise operational amplifier mode.

8. An electrode range eliminating method for electromagnetic prospecting electric field measurement is characterized by comprising the following steps:

s1, coupling an electric field signal through an electrode, and forming an electrode double electric layer concomitantly;

s2, transferring charges of the double electric layers of the electrodes;

s3, obtaining the electric double layer charge quantity of the electrode based on the transfer of the electric double layer charge of the electrode;

and S4, carrying out reverse compensation on the electrode double electric layer according to the electric charge quantity of the electrode double electric layer to finish electrode range elimination.

9. The method for eliminating the pole difference of the electrode for measuring the electric field of the electromagnetic prospecting of claim 8, wherein the reverse compensation is specifically as follows: and acquiring equivalent charges with the same electric double layer charge quantity of the electrode, and performing reverse compensation on the electric double layer of the electrode through the equivalent charges.

Background

The measurement of the ground electric field mainly observes the earth surface component and the space-time distribution of the ground electric field, and the ground electric field can be divided into a ground electric field and a natural electric field according to different field sources, wherein the ground electric field is a variable electric field which is generated by various field sources outside the earth on the ground surface and distributed on the whole ground surface or a larger region; in natural electric fields, the underground medium forms a stable electric field on the earth surface due to various physical and chemical actions.

The ground electric field usually utilizes an electrode and a low-noise amplifying circuit to pick up an electric field signal, and the range of the electrode is the inherent characteristic of the electrode, and the stability of the electrode is influenced by factors such as the ambient temperature, the ion concentration of the electrode and the like. The electrode range is a low-frequency drift signal, the alternating current coupling is a commonly used electrode range elimination method, but the effective electric field signal of a deep ultra-deep medium is lower than the ultra-low frequency of a millisecond or even a ten thousand seconds, and a low-frequency electric field signal amplification circuit is usually a chopper amplifier coupled with a low-input impedance transformer, so that the size of a direct current blocking capacitor of the alternating current coupling is large, the stability is poor, and the range elimination effect is poor. In the direct current coupling mode, too large electrode range leads to output saturation of a large gain amplifying circuit, so that amplification processing of weak electric field signals is limited, therefore, the electrode range is generally required to be limited to be less than 0.1mV, pairing is required in the electrode processing and using processes, chopping modulation is carried out on the electrode output, then automatic compensation is carried out on the signals, the influence of the range can be greatly eliminated, a range extraction method of the electrode range automatic compensation method based on chopping operational amplification adopts a low-pass filter module with a large time constant, the range extraction method only has an effect of comparing static range with low electric field frequency, the range drift effect along with changes of environmental temperature and ion concentration is limited, and the influence of the electrode range cannot be completely eliminated.

According to the existing ground electric field observation records, recorded data simultaneously comprise a ground electric field and electrode pole difference noise, and the frequency of the ground electric field and the frequency of the electrode noise are seriously coincided and cannot be eliminated by adopting a traditional method. And aiming at the problem that the operating amplifier device is saturated due to the fact that the electric field signal amplification and collection midpoint range is extremely poor in a direct current coupling mode, the elimination effect of an alternating current coupling mode is poor, and the problem that dynamic range cannot be eliminated through chopping compensation exists.

Disclosure of Invention

Aiming at the problems, the invention provides an electrode range elimination system and method for electromagnetic prospecting electric field measurement, which aims to solve the technical problems in the prior art, can realize the complete elimination of the electrode range in a mode of compensating range charges through a circuit, and avoid the limitation that the electrode range is less than 0.1mV and the electrode needs to be paired in the processing and using processes of the traditional electric field measurement.

In order to achieve the purpose, the invention provides the following scheme: the invention provides an electrode range eliminating system for measuring an exploration electric field by an electromagnetic method, which comprises: the device comprises an electrode module, an electrode charge extraction module, an instrument amplification module and an electrode charge compensation module;

the electrode module is used for coupling electric field signals and forming an electrode double electric layer;

the electrode charge extraction module is used for extracting the charges transferred by the double electric layers of the electrodes;

the meter amplification module is used for obtaining the charge amount of the electrode double electric layer based on the extraction of the charges transferred by the electrode double electric layer;

and the electrode charge compensation module is used for reversely compensating the equivalent charge into the electrode module through a capacitor according to the charge quantity of the double electric layers of the electrodes so as to finish electrode range elimination.

Preferably, the electrode module includes an electrode ground resistance (Rp), an electrode double layer capacitance (Cp), an electrode double layer capacitance range signal source (ep), a ground electric field signal source (E);

one end of the earth electric field signal source (E) is respectively connected with the electrode grounding resistance (Rp) and the electrode double-layer capacitance range difference signal source (ep), and the other end is grounded; the electrode double layer capacitance range signal source (ep) is connected in series with the electrode double layer capacitance (Cp); the electrode double layer capacitance (Cp) is connected to the electrode ground resistance (Rp); the electrode ground resistance (Rp) and the electrode double layer capacitance (Cp) are both connected to the electrode charge extraction module.

Preferably, the electrode charge extraction module comprises an electrode charge extraction capacitance (Cc); and the electrode charge extraction capacitor (Cc) is respectively connected with the instrument amplification module, the electrode charge compensation module and the electrode module.

Preferably, the instrument amplification module comprises a first amplifier (U1), a second amplifier (U2), a third amplifier (U3), a first resistor (R1), a second resistor (R2), a third resistor (R3), a fourth resistor (R4), a fifth resistor (R5), a sixth resistor (R6) and a seventh resistor (R7);

the positive input ends of the first amplifier (U1) and the second amplifier (U2) are respectively connected with two ends of the electrode charge extraction capacitor (Cc);

the inverting input end of the first amplifier (U1) is respectively connected with the first resistor (R1) and the second resistor (R2); the output end of the first amplifier (U1) is respectively connected with the first resistor (R1) and the fourth resistor (R4);

the inverting input end of the second amplifier (U2) is respectively connected with the second resistor (R2) and the third resistor (R3); the output end of the second amplifier (U2) is respectively connected with the third resistor (R3) and the sixth resistor (R6);

the inverting input end of the third amplifier (U3) is respectively connected with the fourth resistor (R4) and the fifth resistor (R5); the positive input end of the third amplifier (U3) is respectively connected with the sixth resistor (R6) and the seventh resistor (R7); the output end of the third amplifier (U3) is respectively connected with the fifth resistor (R5) and the electrode charge compensation module;

the seventh resistor (R7) is connected to ground.

Preferably, the meter amplification module adopts a low noise amplifier.

Preferably, the electrode charge compensation module comprises a fourth amplifier (U4), an eighth resistor (Rpi), a capacitor (Cpi);

the inverting input end of the fourth amplifier (U4) is respectively connected with the eighth resistor (Rpi) and the capacitor (Cpi); the output of said fourth amplifier (U4) being connected to said capacitor (Cpi) and said electrode charge extraction capacitor (Cc); a positive input of the fourth amplifier (U4) is connected to ground;

the eighth resistor (Rpi) is connected to the output of the third amplifier (U3).

Preferably, the electrode charge compensation module adopts a low noise operational amplifier mode.

An electrode range eliminating method for measuring an electric field of electromagnetic prospecting comprises the following steps:

s1, coupling an electric field signal through an electrode, and forming an electrode double electric layer concomitantly;

s2, transferring charges of the double electric layers of the electrodes;

s3, obtaining the electric double layer charge quantity of the electrode based on the transfer of the electric double layer charge of the electrode;

and S4, carrying out reverse compensation on the electrode double electric layer according to the electric charge quantity of the electrode double electric layer to finish electrode range elimination.

Preferably, the reverse compensation is specifically: and acquiring equivalent charges with the same electric double layer charge quantity of the electrode, and performing reverse compensation on the electric double layer of the electrode through the equivalent charges.

The invention discloses the following technical effects:

the invention starts from the generation principle of the electrode range, realizes the complete elimination of the electrode range by a circuit compensation range charge mode, avoids the traditional electric field measurement requirement that the electrode range is less than 0.1mV, and avoids the limitation that pairing is required in the electrode processing and using processes, can be suitable for the contact type electrode range elimination of any polarized electrode and non-polarized electrode, does not need to consider the size of the electrode range, does not need to pair the electrodes, and greatly reduces the processing cost of the electrodes.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

FIG. 1 is a block diagram of a system of the present invention;

FIG. 2 is a schematic diagram of an electrode step elimination in an embodiment of the present invention;

FIG. 3 is a schematic diagram of charge compensation of an electrode circuit according to an embodiment of the present invention;

fig. 4 is a schematic diagram of an electrode step eliminating circuit according to an embodiment of the invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

Referring to fig. 1-2, the present embodiment provides an electrode pole difference elimination system for measuring an electromagnetic prospecting electric field, including: the device comprises an electrode module, an electrode charge extraction module, an instrument amplification module and an electrode charge compensation module.

The electrode module is used for coupling electric field signals to obtain an electrode double electric layer; the electrode charge extraction module is used for extracting the charges transferred by the double electric layers of the electrodes; the meter amplification module is used for obtaining the charge quantity of the electrode double-layer based on the charge transferred by the electrode double-layer; and the electrode charge compensation module is used for reversely compensating the equivalent charge into the electrode module through a capacitor according to the charge quantity of the double electric layers of the electrodes so as to finish the elimination of the electrode range difference.

The invention starts from the generation principle of the electrode range difference, realizes the complete elimination of the electrode range difference by a way of compensating the range difference charge by a circuit, and avoids the limitation that the electrode range difference is less than 0.1mV and the electrode needs to be paired in the processing and using processes of the traditional electric field measurement.

The range of the electrodes is a result of the generation of an electric double layer at the electrode interface. The amount of electric double layer charge per unit area of the electrode interface is very sensitive to temperature and rapidly decreases as the temperature increases. The first is that the temperature rises, the electric field force weakens, and the adsorption capacity of the electrode surface to ions is reduced; secondly, after the temperature is increased, the viscosity of the solution is reduced, and the adsorption capacity of the electrode surface to ions is reduced. In addition, the amount of electric charge of the electric double layer at the electrode interface increases with the increase of the mass concentration of the solution, but the electric charge amount increases little at high concentration because the electric charge amount is proportional to the square root of the mass of the ions, so that the electric adsorption advantage gradually weakens when the salt content of the raw water is high. Therefore, the influence of the extreme difference in the electrode can be eliminated by canceling the electric double layer charge at the electrode interface by a certain means.

Charge extraction and charge compensation are achieved by capacitive coupling, when the electrode double layer is charged, by connecting an ideal wire to another uncharged capacitor plate, charge transfer must occur until the potentials are equal. The voltage of the extraction capacitor is increased along with the transfer of the charges to the charge extraction capacitor, the transfer amount of the charges can be known by measuring the increase amount of the voltage of the extracted charges, the voltage of the extraction capacitor is zero through charge compensation, and the charges of an electric double layer of the electrode are eliminated, so that the purpose of eliminating the extreme difference is achieved.

Referring to fig. 3, Cp is parasitic capacitance of the electrode and is determined by an electrode double layer, e is an electric double layer potential and is determined by electrode double layer charge, and Rp is electrode ground resistance. Since the electric charge of the electric double layer cannot be kept constant due to factors such as temperature and ion concentration, a very poor fluctuation signal is generated to affect the measurement of the electric field. The invention aims to eliminate the influence of an electric double layer by extracting electric charges of the electric double layer in real time and performing charge compensation, force a circuit model of an electrode to be equal to a simple grounding resistance and further realize accurate electric field measurement.

Referring to fig. 4, the present embodiment provides an electrode step canceling circuit structure; wherein, one conductor has electric charge, and the other conductor does not have electric charge, and after the two conductors contact, the electric charge must be transferred from the conductor with electric charge to the conductor without electric charge until the electric potentials of the two conductors are equal, which is the theoretical basis of the invention patent. Therefore, an electrode charge extraction capacitor is connected to the electrode output lead, a part of the electrode charge is transferred into the extraction capacitor, two ends of the extraction capacitor are extracted, voltage is generated, if the voltage at two ends of the extraction capacitor is controlled to be zero, namely no charge is generated, which is equivalent to indirectly eliminating the charge of the electrode, the electric double layer of the electrode disappears, thereby eliminating the electrode difference, and at the moment, the circuit model of the electrode is equivalent to a ground resistance.

The specific connection mode is as follows:

the equivalent circuit of the electrode module comprises an electrode grounding resistance Rp, an electrode double-layer capacitor Cp, an electrode double-layer capacitor range signal source ep and a ground electric field signal source E; the electrode charge extraction module comprises an electrode charge extraction capacitor Cc; the instrument amplification module comprises a first amplifier U1, a second amplifier U2, a third amplifier U3, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6 and a seventh resistor R7; the electrode charge compensation module comprises a fourth amplifier U4, an eighth resistor Rpi, and a capacitor Cpi.

One end of a ground electric field signal source E is respectively connected with an electrode grounding resistor Rp and an electrode double-layer capacitance range signal source ep, and the other end of the ground electric field signal source E is grounded; an electrode double-layer capacitance range signal source ep is connected in series with an electrode double-layer capacitance Cp; the electrode double-layer capacitor Cp is connected with the electrode grounding resistor Rp; the electrode grounding resistance Rp and the electrode double-layer capacitance Cp are both connected with the electrode charge extraction module.

The electrode charge extraction capacitor Cc is respectively connected with the instrument amplification module, the electrode charge compensation module and the electrode module.

The positive input ends of the first amplifier U1 and the second amplifier U2 are respectively connected with two ends of an electrode charge extraction capacitor Cc; the inverting input end of the first amplifier U1 is respectively connected with the first resistor R1 and the second resistor R2; the output end of the first amplifier U1 is respectively connected with the first resistor R1 and the fourth resistor R4; the inverting input end of the second amplifier U2 is respectively connected with the second resistor R2 and the third resistor R3; the output end of the second amplifier U2 is respectively connected with the third resistor R3 and the sixth resistor R6; the reverse input end of the third amplifier U3 is respectively connected with the fourth resistor R4 and the fifth resistor R5; the positive input end of the third amplifier U3 is respectively connected with the sixth resistor R6 and the seventh resistor R7; the output end of the third amplifier U3 is respectively connected with a charge compensation module of an electrode of a fifth resistor R5; the seventh resistor R7 is connected to ground.

The reverse input end of the fourth amplifier U4 is connected to the eighth resistor Rpi and the capacitor Cpi, respectively; the output end of the fourth amplifier U4 is connected to the capacitor Cpi and the electrode charge extraction capacitor Cc; the positive input end of the fourth amplifier U4 is grounded; the eighth resistor Rpi is connected to the output of the third amplifier U3.

The specific electrode range elimination method is as follows:

s1, coupling an electric field signal through an electrode, and forming an electrode double electric layer concomitantly;

s2, transferring charges of the double electric layers of the electrodes;

s3, obtaining the electric double layer charge quantity of the electrode based on the transfer of the electric double layer charge of the electrode;

and S4, carrying out reverse compensation on the electrode double electric layer according to the electric charge quantity of the electrode double electric layer to finish electrode range elimination.

The reverse compensation is specifically as follows: after the electrode charge extraction module is connected with the electrode module, the charge generated by the electrode double electric layer is extracted, the voltage at two ends of the electrode charge extraction capacitor Cc changes, the charge quantity transferred from the electrode double electric layer to the electrode charge extraction capacitor Cc can be obtained through the low-noise instrument amplification circuit, the capacitor is reversely charged through a PI compensation circuit, the charge is forced to reversely flow to the electrode, the electric double electric layer is offset by the compensation charge, and the purpose that the electrode is equivalent to one grounding resistor is finally achieved.

The extracted charge amplifying circuit can be any low-noise instrument amplifier meeting the requirement of measuring bandwidth, and the operational amplifier in the electrode compensation circuit also has low noise, so that the electrode charge is ensured to be accurately compensated.

The invention discloses the following technical effects:

the invention starts from the generation principle of the electrode range, extracts the capacitor to obtain complete compensation by a circuit compensation range charge mode, realizes complete elimination of the electrode range, avoids the limitation that the traditional electric field measurement requires the electrode range to be less than 0.1mV and pairing is required in the electrode processing and using process, can be suitable for the contact type electrode range elimination of any polarized electrode and non-polarized electrode, does not need to consider the size of the electrode range, does not need to pair the electrodes, and greatly reduces the processing cost of the electrodes.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus once an item is defined in one figure, it need not be further defined and explained in subsequent figures, and moreover, the terms "first", "second", "third", etc. are used merely to distinguish one description from another and are not to be construed as indicating or implying relative importance.

Finally, it should be noted that: the above-mentioned embodiments are only specific embodiments of the present invention, which are used for illustrating the technical solutions of the present invention and not for limiting the same, and the protection scope of the present invention is not limited thereto, although the present invention is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: any person skilled in the art can modify or easily conceive the technical solutions described in the foregoing embodiments or equivalent substitutes for some technical features within the technical scope of the present disclosure; such modifications, changes or substitutions do not depart from the spirit and scope of the present invention in its spirit and scope. Are intended to be covered by the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.