CN203630174U - High precision capacitive voltage divider applied in live-line verification - Google Patents

Abstract

The utility model discloses a high precision capacitive voltage divider applied in live-line verification, and belongs to the capacitive voltage divider technical field; the high precision capacitive voltage divider comprises a high voltage arm capacitor C1, a low voltage arm capacitor C2, a low voltage capacitor lead wire, a high voltage side shield sleeve and a low voltage side shield sleeve; the high voltage arm capacitor C1 is a coaxial cylinder capacitor; the low voltage arm capacitor C2 is a parallel plate capacitor; the high voltage arm capacitor C1 is connected with the low voltage arm capacitor C2 through the low voltage capacitor lead wire; the high voltage side shield sleeve wraps the high voltage arm capacitor C1; the low voltage side shield sleeve wraps the low voltage arm capacitor C2 and the low voltage capacitor lead wire; the high voltage side shield sleeve and the low voltage side shield sleeve commonly cover the whole capacitive voltage divider; the capacitive voltage divider is provided with the shield, thereby effectively reducing the influences to capacitive voltage divider center voltage value by external interferences, and improving measuring precision and stability.

Description

A kind of high-accuracy capacitor voltage divider that is applied to charged verification

Technical field

The utility model relates to capacitive divider technical field, particularly a kind of high-accuracy capacitor voltage divider that is applied to charged verification.

Background technology

Capacitance type potential transformer (capacitor voltage transformer) is mainly used in electric system high pressure level circuitry, is called for short CVT.The primary structure of CVT comprises standard capacitor divider, medium voltage measurement mutual inductor and subsequent conditioning circuit.In the middle of it, voltage measurement mutual inductor and subsequent conditioning circuit can be thought the electromagnetic potential transformer of a low-voltage, its measuring accuracy can be accomplished very high under present working condition, thereby in normal operation, the factor that affects CVT measuring accuracy mainly concentrates on standard capacitor divider.

Standard capacitor divider is generally in series by high-voltage arm main capacitance and low-voltage arm main capacitance, because the main capacitance amount of high-voltage arm is larger, also can adopt the structure of several low capacity capacitances in series at high-voltage arm, also can adopt the structure of several Capacitance parallel connections in low-voltage arm.In the time adding voltage at desirable capacitor two ends, in capacitor, only there is displacement current.But while adding voltage at actual capacitor two ends, how much understand some leakage current and flow through in the insulating material of electric capacity, this part leakage current can change the intrinsic standoff ratio of standard capacitor divider, make measurement occur error.In order to obtain high-precision standard capacitor divider, need to reduce as much as possible the leakage current of standard capacitor divider.

Standard capacitor divider is applied in high-tension occasion, because the volume of self is larger, between meeting and equipment around and the earth, produces stray capacitance.Under the state of normal work, these stray capacitances can cause flowing through stray current in standard capacitor divider.These stray currents can change the intrinsic standoff ratio of standard capacitor divider equally, affect measuring accuracy.Particularly, at the capacitance type potential transformer being applied in on-line correction, on-the-spot working environment is complicated and changeable, and the change of surrounding environment also can exert an influence to stray capacitance.Therefore, in order to obtain high-precision standard capacitor divider, need to take measures the stray capacitance that debases the standard between capacitive divider and surrounding environment, reduce the impact of nearby device electriferous state on standard capacitor divider measuring accuracy.

Due to the lot of advantages that CVT shows in voltage levels circuit, Chinese scholars and company have carried out a large amount of research to capacitance type potential transformer.The direction of research have analyze the reason that error produces under stable situation and improve measuring accuracy, about the research of transient characterisitics and improve transient response and weaken ferroresonance etc.But external electromagnetic environment and nearby device are still very outstanding on the impact of standard capacitor divider.

The chief component portion of capacitance type potential transformer comprises that two-stage standard capacitor divider, A/D modular converter, data processing module and data show output module, and its structural principle as shown in Figure 1.

Capacitive battery minor voltage transformer (VT) is in the time of measuring voltage, first be, by two-stage standard capacitor divider, the high voltage on bus is reduced to the medium voltage for low-voltage arm capacitor two ends, then by A/D modular converter, medium voltage simulating signal is converted to digital signal, in the data processing module of secondary side, signal data is processed, obtain the voltage signal of primary side, and calculate its amplitude and phase place, finally show that by data output module exports.

In the basic structure of CVT, the precision and stability of standard capacitor divider has very important impact to the measuring accuracy of CVT, and the content of this chapter is mainly conceived to the shielding measure of standard capacitor divider.

Standard capacitor divider structural circuit figure ideally as shown in Figure 2 (a) shows, only has displacement current to flow through in electric capacity ideally, and the voltage relationship of low-voltage arm and high-voltage arm as shown in Equation (1).But in service in reality, owing to there is leakage current in standard capacitance, is equivalent to a resistance in parallel with standard capacitance by leakage current, and the standard capacitor divider structure of actual motion is as shown in Fig. 2 (b).

${\mathrm{<figure-callout\; id="2"\; label="U"\; filenames="HDA0000430175760000014.png"\; state="\{\{state\}\}">U</figure-callout>}}_2=\frac{C_1}{C_1+C_2}{U}_2---\left(1\right)$

The intrinsic standoff ratio of the standard capacitor divider of ideal situation and frequency-independent, but the intrinsic standoff ratio of the standard voltage divider in actual motion is relevant with frequency, as formula (2) and (3).

${\mathrm{<figure-callout\; id="2"\; label="U"\; filenames="HDA0000430175760000014.png"\; state="\{\{state\}\}">U</figure-callout>}}_2=\frac{R_2\left|\right|(1/\mathrm{j\&omega;}{C}_2)}{R_1\left|\right|(1/\mathrm{j\&omega;}{C}_1)+R_2\left|\right|(1/\mathrm{j\&omega;}{C}_2)}{U}_1---\left(2\right)$

${\mathrm{<figure-callout\; id="2"\; label="U"\; filenames="HDA0000430175760000014.png"\; state="\{\{state\}\}">U</figure-callout>}}_2=\frac{R_1+\mathrm{J\&omega;}{C}_1{R}_1{R}_2}{R_1+{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="HDA0000430175760000014.png"\; state="\{\{state\}\}">R</figure-callout>}}_2+\mathrm{j\&omega;}{R}_1{R}_2(C_1+C_2)}{U}_1---\left(3\right)$

Can see, due to the existence of leakage current equivalent resistance, the intrinsic standoff ratio precision of actual standard capacitor divider can be received impact, reduces leakage current, just can improve the precision of standard capacitor divider.

Utility model content

In order to address the above problem, the utility model proposes a kind of high-accuracy capacitor voltage divider that is applied to charged verification that improves measuring accuracy and Measurement sensibility by reducing stray capacitance between capacitance electrode and nearby device.

The high-accuracy capacitor voltage divider of charged verification that what the utility model provided be applied to comprises high-voltage arm capacitor C ₁, low-voltage arm capacitor C ₂, low-voltage capacitance lead-in wire, high-pressure side bell housing and low-pressure side bell housing, described high-voltage arm capacitor C ₁for concentric cylinder electric capacity, described low-voltage arm capacitor C ₂for parallel plate capacitor, described high-voltage arm capacitor C ₁go between and be connected in low-voltage arm capacitor C by low-voltage capacitance ₂, described high-pressure side bell housing envelopes described high-voltage arm capacitor C ₁, described low-pressure side bell housing envelopes described low-voltage arm capacitor C ₂with low-voltage capacitance lead-in wire, described high-pressure side bell housing has covered whole described capacitive divider together with low-pressure side bell housing.

As preferably, described high-voltage arm capacitor C ₁carried out smooth treatment.

As preferably, described high-voltage arm capacitor C ₁between electrode, fill SF ₆air gap.

As preferably, described low-voltage arm capacitor C ₂filled media is film paper complex media, specific inductive capacity 3.5.

As preferably, described capacitive divider also comprises multiple temperature sensors, is used to indicate the temperature in described capacitive divider.

What the utility model provided is applied to the high-accuracy capacitor voltage divider of charged verification owing to having introduced shielding, can effectively reduce the impact of external interference on capacitive divider intermediate voltage value, improves the precision and stability of measuring.

Brief description of the drawings

Fig. 1 is CVT structure principle chart of the prior art;

Fig. 2 (a) is CVT structure schematic diagram in the ideal case in prior art;

Fig. 2 (b) is the schematic diagram of CVT structure under actual conditions in prior art;

The structural representation of the high-accuracy capacitor voltage divider that is applied to charged verification that Fig. 3 provides for the utility model embodiment mono-;

The structural representation of the high-accuracy capacitor voltage divider that is applied to charged verification that Fig. 4 provides for the utility model embodiment bis-;

Temperature error-temperature broken line graph of the high-accuracy capacitor voltage divider that is applied to charged verification that Fig. 5 provides for the utility model embodiment bis-.

Embodiment

In order to understand the utility model in depth, below in conjunction with drawings and the specific embodiments, the utility model is elaborated.

Embodiment mono-

The high-accuracy capacitor voltage divider of charged verification that what the utility model provided be applied to comprises high-voltage arm capacitor C ₁2, low-voltage arm capacitor C ₂4, low-voltage capacitance lead-in wire 6, high-pressure side bell housing 1 and low-pressure side bell housing 3, high-voltage arm capacitor C ₁2 is concentric cylinder electric capacity, low-voltage arm capacitor C ₂4 is parallel plate capacitor, high-voltage arm capacitor C ₁2 are gone between and 6 are connected in low-voltage arm capacitor C by low-voltage capacitance ₂4, high-pressure side bell housing 1 envelopes high-voltage arm capacitor C ₁2, low-pressure side bell housing 3 envelopes low-voltage arm capacitor C ₂4 and low-voltage capacitance lead-in wire 6, high-pressure side bell housing 1 has covered whole capacitive divider together with low-pressure side bell housing 3, and label 5 is intermediate voltage signal output terminal.Emulation adopts ANSOFT software to carry out, and through calculating emulation, the maximal value of its electric field appears between the electrode of plane-parallel capacitor, and the electric field intensity value of remainder is lower, meets the requirement of insulation.

Respectively to have shielding noiseless, have shielding to have interference, unshieldedly noiselessly, unshielded have the capacitive divider disturbing in four kinds of situations to carry out emulation, the intermediate voltage value obtaining is as shown in table 1:

The table 1 medium voltage simulation result table of comparisons

As can be seen from Table 1, extraneous interference does not affect intermediate voltage value, have disturb and when noiseless the difference of medium voltage be 0.00%.And adopt prior art provide capacitive divider time, have and disturb and when noiseless, medium voltage difference is 10.79%, as can be seen here, what the utility model provided is applied to the high-accuracy capacitor voltage divider of charged verification owing to having introduced shielding, can effectively reduce the impact of external interference on capacitive divider intermediate voltage value, improve the precision and stability of measuring.

Wherein, high-voltage arm capacitor C ₁2 can carry out smooth treatment, thereby reduced electric field intensity.

Wherein, high-voltage arm capacitor C ₁between electrode, can fill SF ₆air gap, to utilize its good electrical insulation properties and excellent arc extinction performance.

Wherein, low-voltage arm capacitor C ₂filled media is film paper complex media, specific inductive capacity 3.5, and to utilize its temperature coefficient little, electric capacity is stable, the performance that moisture resistance is good.

Embodiment bis-

Referring to accompanying drawing 4, what the utility model embodiment bis-provided be applied to the high-accuracy capacitor voltage divider of charged verification and the difference of the high-accuracy capacitor voltage divider that is applied to charged verification that the utility model embodiment mono-provides is,

The utility model capacitive divider also comprises multiple temperature sensors 7, in the present embodiment, temperature sensor 7 is arranged at respectively 6 different positions in this capacitive divider, be used to indicate diverse location in capacitive divider temperature, thereby further reduce the impact of temperature, improve the stability of intrinsic standoff ratio.

The method that the capacitive divider that application the utility model embodiment bis-provides is measured medium voltage comprises the following steps:

The temperature recording according to each temperature sensor 7 adopts method of interpolation to obtain temperature error in temperature error-temperature broken line graph as shown in Figure 5;

According to temperature error, the medium voltage being obtained by capacitive divider actual measurement is revised, obtained medium voltage true value.

Wherein, the preparation method of temperature error-temperature broken line graph as shown in Figure 5 comprises the following steps:

Capacitive divider is put into temperature-controlled chamber, at different temperature spots, capacitive divider is applied to rated voltage, measure the temperature characterisitic data of capacitive divider, capacitive divider temperature characterisitic data comprise temperature value, trial voltage value, intermediate voltage value and temperature error values, in the present embodiment, capacitive divider temperature characterisitic data are as shown in table 2:

Table 2 temperature characterisitic data

Temperature (DEG C)	Rated voltage (KV)	Medium voltage (V)	Temperature error (%)
				0.1	50.641	11.6263	0.034
15.3	50.527	11.6002	0.035
				30.1	50.769	11.6549	0.027
45.2	50.749	11.6504	0.028
				59.6	50.970	11.7034	0.048

；

Draw temperature error-temperature broken line graph as shown in Figure 5 according to temperature error values and temperature value.

Wherein, the temperature range in temperature-controlled chamber is 0～60 DEG C.

Wherein, temperature spot comprises multiple, and in the present embodiment, temperature spot is 5 shown in table 2, and wherein, more these temperature error-temperature broken line graphs of the quantity of temperature spot are more accurate.

Above-described embodiment; the purpose of this utility model, technical scheme and beneficial effect are further described; institute is understood that; the foregoing is only embodiment of the present utility model; be not limited to the utility model; all within spirit of the present utility model and principle, any amendment of making, be equal to replacement, improvement etc., within all should being included in protection domain of the present utility model.

Claims (5)

1. a high-accuracy capacitor voltage divider that is applied to charged verification, is characterized in that, comprises high-voltage arm capacitor C ₁, low-voltage arm capacitor C ₂, low-voltage capacitance lead-in wire, high-pressure side bell housing and low-pressure side bell housing, described high-voltage arm capacitor C ₁for concentric cylinder electric capacity, described low-voltage arm capacitor C ₂for parallel plate capacitor, described high-voltage arm capacitor C ₁go between and be connected in low-voltage arm capacitor C by low-voltage capacitance ₂, described high-pressure side bell housing envelopes described high-voltage arm capacitor C ₁, described low-pressure side bell housing envelopes described low-voltage arm capacitor C ₂with low-voltage capacitance lead-in wire, described high-pressure side bell housing has covered whole described capacitive divider together with low-pressure side bell housing.

2. capacitive divider according to claim 1, is characterized in that, described high-voltage arm capacitor C ₁carried out smooth treatment.

3. capacitive divider according to claim 1, is characterized in that, described high-voltage arm capacitor C ₁between electrode, fill SF ₆air gap.

4. capacitive divider according to claim 1, is characterized in that, described low-voltage arm capacitor C ₂filled media is film paper complex media, specific inductive capacity 3.5.

5. according to arbitrary described capacitive divider in claim 1～4, it is characterized in that, described capacitive divider also comprises multiple temperature sensors, is used to indicate the temperature in described capacitive divider.

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