CN115792343B - Accuracy-adjustable voltage sensor and accuracy adjustment method thereof - Google Patents
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Abstract
The invention discloses an accuracy adjustable voltage sensor and an accuracy adjusting method thereof, wherein the voltage sensor comprises a capacitive voltage divider, an isolation transformer, an accuracy correction loop and a load; the capacitive voltage divider consists of a high-voltage capacitor and a low-voltage capacitor, and the accuracy correction loop consists of a fixed resistor, a first adjustable resistor and a second adjustable resistor; the accuracy adjustment method comprises the following steps: constructing a capacitive voltage division type voltage sensor equivalent circuit based on the davitin theorem; calculating a voltage dividing ratio by using an equivalent circuit of the capacitive voltage dividing voltage sensor; calculating the accuracy of the voltage sensor according to the transformation ratio of the inductance sensor; and correcting the error of the voltage sensor by using an adjustable resistor. The invention not only can ensure the same service life of the sensor and the primary switch and solve the problem that the accuracy of the capacitive voltage-dividing voltage sensor is not easy to ensure, but also can meet the accuracy requirement, does not need pairing sorting, has simple production process and is suitable for mass production.
Description
Technical Field
The invention relates to the technical field of voltage sensors, in particular to an accuracy-adjustable voltage sensor and an accuracy adjusting method thereof.
Background
The secondary integration switch is key equipment for intelligent power distribution network construction, is novel switching equipment for organically integrating traditional primary switching equipment, a transformer and a secondary control terminal, can realize automatic and rapid isolation of on-site control and faults of the switch, and improves active sensing and decision control capability of the running state of the power distribution network.
The mutual inductor is used for detecting voltage and current signals of the power distribution network and is a core element of secondary fusion power distribution equipment. The traditional transformer has the problems of large volume, easy saturation, easy resonance and the like, and is difficult to adapt to the development trend of miniaturization, modularization, intellectualization and integration of secondary fusion equipment. The capacitive voltage dividing voltage sensor has the advantages of small volume, simple insulating structure, wide measuring range and the like, and can be miniaturized and easily fused with other power distribution equipment to be integrally designed. The method is widely applied to devices such as a secondary fusion column switch and the like.
As shown in fig. 3, the secondary fusion on-column switch complete equipment mainly comprises: (1) the pole-mounted switch body, a Feeder Terminal (FTU), a power supply voltage transformer (PT) and a connecting cable assembly. In general, a voltage sensor is built in the switch body (1), and a detected signal is transmitted to the feeder terminal (3) through the cable assembly (4) to realize voltage detection of the high-voltage wire.
The secondary fusion on-column switch is outdoor operation equipment, the voltage sensor is required to keep high accuracy in a higher temperature range, the national grid company requires the voltage sensor used by the secondary fusion switch to have a transformation ratio of (10000%
): (3.25//>
) The accuracy is required to be 0.5 level, and the temperature used is in the range of-40 ℃ to +70 ℃. The principles of the present capacitive voltage division voltage sensor are generally two types, as shown in fig. 4 and 5, respectively.
For the voltage sensor of the principle of fig. 4, the voltage dividing capacitor used is required to have no or little change in capacitance value over a wide temperature range in order to meet the accuracy requirement. Since capacitor fabrication materials generally vary with temperature, the dielectric constant exhibited varies somewhat, and thus the capacitance of the capacitor varies at different temperatures. Meanwhile, due to the manufacturing process problem of the capacitor, the capacitor with the same material at the same temperature has capacitance errors, and even if a voltage division capacitor with low temperature drift and high precision is used, the accuracy requirement is difficult to meet.
The voltage sensor using the principle of fig. 4, because the primary side and the secondary side of the sensor do not take isolation measures, if the disconnection between the voltage dividing elements or poor connection of the grounding wires and the like occur, high voltage can be generated on the load, and the load damage and even personal injury can be caused.
For the above reasons, there are also voltage sensors with isolation transformers that employ the principle of fig. 5. In addition to the voltage sensor based on the principle of fig. 5, the accuracy of the voltage sensor is affected by the capacitance error of the voltage dividing capacitor, and the isolation transformer also brings a certain additional error (even if a high-accuracy isolation transformer is used).
In order to meet the accuracy requirement of the voltage sensor, in the practical design of the capacitive voltage division type voltage sensor, the following method is generally adopted:
(1) the capacitance matching method is adopted: selecting a high-voltage capacitor and a low-voltage capacitor with close temperature characteristics, and matching capacitance values to enable the matched voltage division ratio to meet the requirement;
(2) and a feedback calibration circuit formed by active devices such as an operational amplifier is added to achieve the accuracy required by the secondary fusion equipment.
However, the first method adopts a method that capacitance matching meets the accuracy of the sensor, the production efficiency is low, partial capacitance is difficult to match, and the production cost is high. Meanwhile, the high-voltage capacitor, the low-voltage capacitor and the like which form a sensor are required to be strictly paired in the whole production process of the sensor, so that mixing is avoided, otherwise, the whole sensor is possibly scrapped; the second method adopts a feedback calibration circuit formed by active devices such as operational amplifiers and the like to meet the accuracy of the sensor, and the active electronic devices such as operational amplifiers and the like are required to be used, so that the service life is short. The switch is built in a secondary fusion switch, is not matched with the service life of a primary switch, and influences the service life of the switch.
For the problems in the related art, no effective solution has been proposed at present.
Disclosure of Invention
(one) solving the technical problems
Aiming at the defects of the prior art, the invention provides the accuracy-adjustable voltage sensor and the accuracy adjustment method thereof, which have the advantages of ensuring the same service lives of the sensor and the primary switch, solving the problem that the accuracy of the capacitive voltage-dividing voltage sensor is not easy to ensure, meeting the accuracy requirement of the sensor, having no need of pairing sorting, having simple production process and being suitable for mass production, and further solving the problems in the background art.
(II) technical scheme
In order to realize the advantages that the sensor can ensure the same service life of the sensor and the primary switch, the problem that the accuracy of the capacitive voltage-dividing voltage sensor is not easy to ensure is solved, the sensor can meet the accuracy requirement, the paired sorting is not needed, the production process is simple, and the capacitive voltage-dividing voltage sensor is suitable for mass production, and the specific technical scheme adopted by the capacitive voltage-dividing voltage sensor is as follows:
according to one aspect of the present invention, there is provided an accuracy adjustable voltage sensor comprising a capacitive voltage divider, an isolation transformer, an accuracy correction loop and a load;
the capacitive voltage divider consists of a high-voltage capacitor and a low-voltage capacitor, one end of the high-voltage capacitor is connected with a high-voltage main loop of a secondary fusion device, the other end of the high-voltage capacitor is connected with one end of the low-voltage capacitor, and the other end of the low-voltage capacitor is grounded;
one end of the primary side of the isolation transformer is connected between the high-voltage capacitor and the low-voltage capacitor, the other end of the primary side of the isolation transformer is connected between the low-voltage capacitor and the ground, and the secondary side of the isolation transformer is connected with two ends of the accuracy correction loop;
the accuracy correction loop consists of a fixed resistor, a first adjustable resistor and a second adjustable resistor, and the fixed resistor and the first adjustable resistor are connected in series and then connected in parallel with the second adjustable resistor;
the two ends of the load are respectively connected with the two ends of the accuracy correction loop.
Further, the high-voltage capacitor and the low-voltage capacitor are respectively formed by combining 1 or more capacitors in series and parallel.
Further, the resistance value of the fixed resistor is 8-10 k omega, the resistance value of the first adjustable resistor is 0-5 k omega, and the resistance value of the second adjustable resistor is 0-2 k omega.
Further, the load impedance of the load is greater than Ω.
According to another aspect of the present invention, there is provided an accuracy adjustment method of an accuracy-adjustable voltage sensor, the accuracy adjustment method comprising the steps of:
s1, constructing a capacitive voltage division type voltage sensor equivalent circuit based on the davitinin theorem;
s2, calculating a voltage dividing ratio by using an equivalent circuit of the capacitive voltage dividing voltage sensor to obtain a transformation ratio of the voltage sensor;
s3, calculating the accuracy of the voltage sensor according to the transformation ratio of the voltage sensor to obtain an error of the voltage sensor;
s4, correcting errors of the voltage sensor by using the first adjustable resistor and the second adjustable resistor.
Further, constructing the equivalent circuit of the capacitive voltage division type voltage sensor based on the davidian theorem comprises the following steps:
and carrying out circuit equivalent transformation on the capacitive voltage divider part according to the davitinin theorem, and carrying out T-shaped equivalent transformation on the isolation transformer to obtain the capacitive voltage division type voltage sensor equivalent circuit.
Further, calculating the voltage dividing ratio by using the equivalent circuit of the capacitive voltage dividing voltage sensor to obtain the transformation ratio of the voltage sensor comprises the following steps:
s21, calculating primary side leakage impedance Z of capacitive voltage divider and isolation transformer t1 The combined impedance Z after series connection 1 Wherein the impedance Z is synthesized 1 The calculation formula of (2) is as follows:
wherein C is 1 Representing the capacitance of the high voltage capacitor of the capacitive divider, C 2 A value Rong Rong of the capacitor divider, j represents a complex number, and j 2 -1, ω represents angular frequency, ω=2pi f, f=50 Hz;
s22, calculating accuracy correction loop impedance and load impedance Z b Synthetic impedance Z after parallel connection 2 Wherein the impedance Z is synthesized 2 The calculation formula of (2) is as follows:
wherein R is h1 And R is h2 An adjustable resistor representing an accuracy correction loop, R 1 Representing the accuracy correction loop fixed resistance;
s23, calculating the total impedance Z of the equivalent circuit of the capacitive voltage dividing voltage sensor, wherein the calculation formula of the total impedance Z is as follows:
wherein Z is t0 Represents the excitation impedance, Z, of the isolation transformer t2 Representing the secondary side leakage impedance of the isolation transformer;
s24, analyzing an equivalent circuit of the capacitor voltage dividing type voltage sensor and calculating a transformation ratio K of the voltage sensor, wherein the calculation formula of the transformation ratio K of the voltage sensor is as follows:
wherein V is 1 Representing the input voltage of the voltage sensor, V 2 Representing an output voltage of the voltage sensor;
s25, analyzing a calculation formula of the transformation ratio K of the simplified voltage sensor to obtain:
further, calculating the accuracy of the voltage sensor according to the transformation ratio of the voltage sensor, and obtaining the error of the voltage sensor comprises the following steps:
s31, taking a voltage sensor component element as a nominal transformation ratio K of a sensor GC The calculation formula for obtaining the nominal transformation ratio is as follows:
s32, calculating accuracy of the voltage sensor based on a nominal transformation ratio of the sensor to obtain an error of the voltage sensor
Wherein the error of the voltage sensor is +.>
The calculation formula of (2) is as follows:
s33, analyzing error of simplified voltage sensor
The calculation formula of (2) is obtained:
further, the correction of the voltage sensor error by using the first adjustable resistor and the second adjustable resistor comprises the following steps:
s41, taking the second adjustable resistor as an error rough adjustment resistor of the voltage sensor, and realizing initial adjustment of the error of the voltage sensor by changing the resistance value of the second adjustable resistor;
s42, taking the first adjustable resistor as an error fine-tuning resistor of the voltage sensor, and realizing accurate adjustment of the error of the voltage sensor by changing the resistance value of the first adjustable resistor until the accuracy meets the requirement.
Further, the adjustable range of the resistance value of the first adjustable resistor is 0 omega-5 k omega, the adjustable range of the resistance value of the second adjustable resistor is 0 omega-2 k omega, and the first adjustable resistor and the second adjustable resistor are both positioned in the middle position after the assembly is completed.
(III) beneficial effects
Compared with the prior art, the invention provides the accuracy adjustable voltage sensor and the accuracy adjusting method thereof, which have the following beneficial effects:
(1) The invention provides a voltage sensor accuracy correction method which is formed by completely using passive impedance elements (resistors, capacitors and inductors), can ensure the same service life of a sensor and a primary switch, and can effectively solve the problem that the accuracy of a capacitive voltage division type voltage sensor is not easy to ensure.
(2) The invention uses the impedance elements such as the adjustable resistor and the like to form the voltage sensor correction loop, so that the sensor error can be respectively subjected to rough adjustment and fine adjustment by adjusting the resistance values of the two variable resistors after the production is finished, the sensor can meet the accuracy requirement, the paired sorting is not needed, the production process is simple, and the method is suitable for mass production.
(3) The sensor calibration device can calibrate the sensor in the sensor delivery test process, improves the production efficiency, ensures the production qualification rate and reduces the production cost; and moreover, by providing the capacitive voltage division type voltage sensor based on the sensor correction method, accuracy is ensured more easily, and safety is higher.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed 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 other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of an accuracy adjustable voltage sensor according to an embodiment of the invention;
FIG. 2 is an equivalent circuit diagram of a capacitive voltage divider type voltage sensor in a method for adjusting accuracy of an accuracy adjustable voltage sensor according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a prior art secondary fusion on-column switch kit;
FIG. 4 is a schematic diagram of a prior art capacitive voltage division voltage sensor;
fig. 5 is a schematic diagram of a prior art capacitive tap voltage sensor with an isolation transformer.
In the figure:
10. a capacitive voltage divider; 11. a high voltage capacitor; 12. a low voltage capacitor; 20. an isolation transformer; 30. an accuracy correction loop; 31. a fixed resistor; 32. a first adjustable resistor; 33. a second adjustable resistor; 40. and (3) loading.
Detailed Description
For the purpose of further illustrating the various embodiments, the present invention provides the accompanying drawings, which are a part of the disclosure of the present invention, and which are mainly used to illustrate the embodiments and, together with the description, serve to explain the principles of the embodiments, and with reference to these descriptions, one skilled in the art will recognize other possible implementations and advantages of the present invention, wherein elements are not drawn to scale, and like reference numerals are generally used to designate like elements.
According to an embodiment of the invention, an accuracy adjustable voltage sensor and an accuracy adjusting method thereof are provided.
The invention will now be further described with reference to the drawings and detailed description, as shown in fig. 1, according to one embodiment of the invention, there is provided an accuracy adjustable voltage sensor comprising a capacitive voltage divider 10, an isolation transformer 20, an accuracy correction loop 30 and a load 40;
the capacitive voltage divider 10 is composed of a high-voltage capacitor 11 and a low-voltage capacitor 12, one end of the high-voltage capacitor 11 is connected with a high-voltage main circuit of a secondary fusion device, the other end of the high-voltage capacitor 11 is connected with one end of the low-voltage capacitor 12, and the other end of the low-voltage capacitor 12 is grounded;
one end of the primary side of the isolation transformer 20 is connected between the high-voltage capacitor 11 and the low-voltage capacitor 12, the other end of the primary side of the isolation transformer 20 is connected between the low-voltage capacitor 12 and the ground, and the secondary side of the isolation transformer 20 is connected with two ends of the accuracy correction loop 30;
the accuracy correction loop 30 is composed of a fixed resistor 31, a first adjustable resistor 32 and a second adjustable resistor 33, wherein the fixed resistor 31 and the first adjustable resistor 32 are connected in series and then connected with the second adjustable resistor 33 in parallel, the second adjustable resistor 33 is used for coarse adjustment of the accuracy of the sensor, and the first adjustable resistor 32 is used for fine adjustment of the accuracy of the sensor;
both ends of the load 40 are connected to both ends of the accuracy correction loop 30, respectively.
The high-voltage capacitor 11 and the high-voltage capacitor 12 are formed by combining 1 or more capacitors in series and parallel, respectively. The resistance value of the fixed resistor 31 is about 8k omega to 10k omega, the resistance value of the first adjustable resistor 32 is adjustable to be 0 omega to 5k omega, and the resistance value of the second adjustable resistor 33 is adjustable to be 0 omega to 2k omega. The load impedance of the load 40 is greater than Ω.
According to another embodiment of the present invention, as shown in fig. 2, there is provided an accuracy adjusting method of an accuracy-adjustable voltage sensor, the accuracy adjusting method including the steps of:
s1, constructing a capacitive voltage division type voltage sensor equivalent circuit based on the davitinin theorem;
in particular, according to the Dai Weining theorem, the voltage divider section may be equivalently the circuit across a, b in FIG. 2, where V 1 10000 +.f for 10kV distribution network system phase voltage
V, V; and meanwhile, carrying out T-shaped equivalent transformation on the isolation transformer. The equivalent transformation of the voltage sensor is shown in fig. 2.
S2, calculating a voltage dividing ratio by using an equivalent circuit of the capacitive voltage dividing voltage sensor to obtain a transformation ratio of the voltage sensor;
specifically, in the equivalent circuit, the capacitive voltage divider and the primary side leakage impedance Z of the isolation transformer t1 Series connection, to simplify the calculation, their combined impedance is set to Z 1 Wherein the impedance Z is synthesized 1 The calculation formula of (2) is as follows:
wherein C is 1 Representing the capacitance of the high voltage capacitor of the capacitive divider, C 2 Representing low voltage capacitance of capacitive dividerJ represents a complex number, and j 2 -1, ω represents angular frequency, ω=2pi f, f=50 Hz;
in the equivalent circuit, the circuit impedance and the load impedance Z are corrected b Parallel connection, to simplify the calculation, their combined impedance is set to Z 2 Wherein the impedance Z is synthesized 2 The calculation formula of (2) is as follows:
wherein R is h1 And R is h2 An adjustable resistor representing an accuracy correction loop, R 1 Representing the accuracy correction loop fixed resistance;
in the equivalent circuit, calculating the total impedance Z of the equivalent circuit of the capacitive voltage dividing voltage sensor, wherein the calculation formula of the total impedance Z is as follows:
wherein Z is t0 Represents the excitation impedance, Z, of the isolation transformer t2 Representing the secondary side leakage impedance of the isolation transformer;
from the circuit analysis it is known that:
the transformation ratio K of the voltage sensor is:
wherein V is 1 Representing the input voltage of the voltage sensor, V 2 Representing an output voltage of the voltage sensor;
in brackets above, item 4 is ignored (item 4 is very small) and the resultant impedance Z 1 Substitution results in:
s3, calculating the accuracy of the voltage sensor according to the transformation ratio of the voltage sensor to obtain an error of the voltage sensor;
in particular, the transformation ratio in the case of using the sensor component as the ideal component is the nominal transformation ratio K of the sensor GC The method comprises the following steps:
the method comprises the steps of carrying out a first treatment on the surface of the The accuracy of the sensor (i.e. sensor error) is:
and due to the resultant impedance Z 2 Z in the calculation formula of (2) b >>R h2 And Z is b >>R h1 + R 1 Therefore, it is obtained:
s4, correcting errors of the voltage sensor by using the first adjustable resistor and the second adjustable resistor.
Specifically, as can be seen from the calculation formula of the sensor error obtained in S3, the sensor produced according to the same design, C 1 、C 2 、Zt 1 、Z t2 、Z t0 There are manufacturing differences, especially C 1 、C 2 The difference is relatively large, which may make it difficult to meet the sensor accuracy. But for a particular oneFor the sensor, Z t1 、Z t2 、Z t0 、C 1 、C 2 Is fixed, and Z 2 By adjusting R h2 And R is h1 Change, thus can be achieved by changing Z 2 Correcting sensor accuracy
。
Due to R h2 Can be adjustable between 0 omega and 2kΩ, R h1 Can be adjusted between 0 omega and 5kΩ, and is easy to know and adjust R h2 In the time-course of which the first and second contact surfaces,
the variation is large, so the error of the sensor is +.>
The influence of (a) is large, and the coarse adjustment resistance is an error in the present embodiment; and adjust R h1 When due to R 1 Restriction of (1)>
The change is small, and the resistor is used as a fine tuning resistor.
In practical use, after the sensor assembly is completed, R is generally first selected from h2 And R is h1 Put in the intermediate position, use the calibrator of the mutual inductor to carry on the accuracy detection, if the accuracy of the sensor exceeds the range of requirement, adjust the rough adjustment resistance R first h2 By changing its resistance, the sensor error is changed to a degree that approximately meets the requirements; then adjust R h1 And (5) fine-tuning the accuracy, and finally, meeting the accuracy requirement.
In addition, the accuracy correction method of the voltage sensor is also applicable to a resistor voltage division type voltage sensor and a resistor-capacitor voltage division type voltage sensor. The adjustable resistance referred to in the present invention may be variously combined. The sensor is calibrated by using an adjustable resistor, and the sensor precision can be calibrated by using an adjustable capacitor, an adjustable inductor and the like according to the same principle.
In summary, by means of the above technical scheme of the present invention, a method for correcting accuracy of a voltage sensor, which is formed by completely using passive impedance elements (resistor, capacitor, inductor), is provided, so that the same service life of the sensor and primary switch can be ensured, and the problem that accuracy of a capacitive voltage-dividing voltage sensor is not easy to ensure can be effectively solved.
In addition, the voltage sensor correction loop is formed by using the impedance elements such as the adjustable resistor and the like, so that the sensor error can be respectively subjected to rough adjustment and fine adjustment by adjusting the resistance values of the two variable resistors after the production is finished, the sensor can meet the accuracy requirement, the matching sorting is not needed, the production process is simple, and the method is suitable for mass production.
In addition, the sensor calibration method can realize the calibration of the sensor in the sensor delivery test process, improve the production efficiency, ensure the production qualification rate and reduce the production cost; and moreover, by providing the capacitive voltage division type voltage sensor based on the sensor correction method, accuracy is ensured more easily, and safety is higher.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.
Claims (4)
1. The accuracy adjusting method of the accuracy adjustable voltage sensor is characterized in that the voltage sensor comprises a capacitive voltage divider (10), an isolation transformer (20), an accuracy correction loop (30) and a load (40); the capacitive voltage divider (10) consists of a high-voltage capacitor (11) and a low-voltage capacitor (12), one end of the high-voltage capacitor (11) is connected with a high-voltage main loop of a secondary fusion device, the other end of the high-voltage capacitor (11) is connected with one end of the low-voltage capacitor (12), and the other end of the low-voltage capacitor (12) is grounded; one end of the primary side of the isolation transformer (20) is connected between the high-voltage capacitor (11) and the low-voltage capacitor (12), the other end of the primary side of the isolation transformer (20) is connected between the low-voltage capacitor (12) and the ground, and the secondary side of the isolation transformer (20) is connected with two ends of the accuracy correction loop (30); the accuracy correction loop (30) consists of a fixed resistor (31), a first adjustable resistor (32) and a second adjustable resistor (33), and the fixed resistor (31) and the first adjustable resistor (32) are connected in series and then connected in parallel with the second adjustable resistor (33); two ends of the load (40) are respectively connected with two ends of the accuracy correction loop (30); the high-voltage capacitor (11) and the low-voltage capacitor (12) are respectively formed by combining 1 or more capacitors in series and parallel; the resistance value of the fixed resistor (31) is 8-10 k omega, the resistance value adjustable range of the first adjustable resistor (32) is 0-5 k omega, and the resistance value adjustable range of the second adjustable resistor (33) is 0-2 k omega; -the load (40) has a load impedance of more than 2mΩ;
the accuracy adjustment method comprises the following steps:
s1, constructing a capacitive voltage division type voltage sensor equivalent circuit based on the davitinin theorem;
s2, calculating a voltage dividing ratio by using an equivalent circuit of the capacitive voltage dividing voltage sensor to obtain a transformation ratio of the voltage sensor;
s3, calculating the accuracy of the voltage sensor according to the transformation ratio of the voltage sensor to obtain an error of the voltage sensor;
s4, correcting errors of the voltage sensor by using the first adjustable resistor and the second adjustable resistor;
the method for constructing the capacitive voltage division type voltage sensor equivalent circuit based on the davidian theorem comprises the following steps:
performing circuit equivalent transformation on the capacitive voltage divider part according to the davitin theorem, and performing T-shaped equivalent transformation on the isolation transformer to obtain an equivalent circuit of the capacitive voltage division type voltage sensor;
the voltage dividing ratio is calculated by using the equivalent circuit of the capacitive voltage dividing type voltage sensor, and the voltage transformation ratio of the voltage sensor is obtained by the following steps:
s21, calculating a capacitive voltage dividerIsolation transformer primary side leakage impedance Z t1 The combined impedance Z after series connection 1 Wherein the impedance Z is synthesized 1 The calculation formula of (2) is as follows:
wherein C is 1 Representing the capacitance of the high voltage capacitor of the capacitive divider, C 2 A value Rong Rong of the capacitor divider, j represents a complex number, and j 2 -1, ω represents angular frequency, ω=2pi f, f=50 Hz;
s22, calculating accuracy correction loop impedance and load impedance Z b Synthetic impedance Z after parallel connection 2 Wherein the impedance Z is synthesized 2 The calculation formula of (2) is as follows:
wherein R is h1 And R is h2 An adjustable resistor representing an accuracy correction loop, R 1 Representing the accuracy correction loop fixed resistance;
s23, calculating the total impedance Z of the equivalent circuit of the capacitive voltage dividing voltage sensor, wherein the calculation formula of the total impedance Z is as follows:
wherein Z is t0 Represents the excitation impedance, Z, of the isolation transformer t2 Representing the secondary side leakage impedance of the isolation transformer;
s24, analyzing an equivalent circuit of the capacitor voltage dividing type voltage sensor and calculating a transformation ratio K of the voltage sensor, wherein the calculation formula of the transformation ratio K of the voltage sensor is as follows:
wherein V is 1 Representing the input voltage of the voltage sensor, V 2 Representing an output voltage of the voltage sensor;
s25, analyzing a calculation formula of the transformation ratio K of the simplified voltage sensor to obtain:
2. the accuracy adjustment method of an accuracy adjustable voltage sensor according to claim 1, wherein calculating the accuracy of the voltage sensor according to the transformation ratio of the voltage sensor, obtaining the error of the voltage sensor comprises the steps of:
s31, taking a voltage sensor component element as a nominal transformation ratio K of a sensor GC The calculation formula for obtaining the nominal transformation ratio is as follows:
s32, calculating accuracy of the voltage sensor based on a nominal transformation ratio of the sensor to obtain an error of the voltage sensor
Wherein the error of the voltage sensor is +.>
The calculation formula of (2) is as follows:
s33, analyzing error of simplified voltage sensor
The calculation formula of (2) is obtained:
3. the accuracy adjustment method of an accuracy adjustable voltage sensor according to claim 2, wherein the correction of the voltage sensor error using the first adjustable resistor and the second adjustable resistor comprises the steps of:
s41, taking the second adjustable resistor as an error rough adjustment resistor of the voltage sensor, and realizing initial adjustment of the error of the voltage sensor by changing the resistance value of the second adjustable resistor;
s42, taking the first adjustable resistor as an error fine-tuning resistor of the voltage sensor, and realizing accurate adjustment of the error of the voltage sensor by changing the resistance value of the first adjustable resistor until the accuracy meets the requirement.
4. The accuracy adjusting method of the accuracy adjustable voltage sensor according to claim 3, wherein the resistance value adjustable range of the first adjustable resistor is 0 Ω -5 kΩ, the resistance value adjustable range of the second adjustable resistor is 0 Ω -2 kΩ, and the first adjustable resistor and the second adjustable resistor are both located at intermediate positions after the assembly is completed.
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