CN102053191A - Electronic voltage transformer using data fusion technology and error calibration method thereof - Google Patents

Abstract

The invention discloses an electronic voltage transformer using data fusion technology and an error calibration method thereof. The error calibration method comprises the following steps of: acquiring a secondary measured voltage by using a capacitive voltage divider and a sampling resistor R, accessing the voltage to a data acquisition processor for sampling, and tracing the frequency of the voltage; accessing a signal of a temperature sensor to the data acquisition processor, and computing the temperatures of measuring points; dynamically computing a divided voltage ratio of the capacitive voltage divider according to the temperature variation of the measuring points by using data acquisition device processing software so as to modify a transformation ratio error of the transformer; dynamically computing phase deviation according to signal frequency variation by using the data acquisition device processing software so as to modify a phase error; and outputting a digital sampling value through an optical fiber interface. The device is simple in structure, safe and practical; errors caused by manufacturing factors, temperature and signal acquisition circuits and the like can be effectively modified and restrained; and the measuring accuracy, temperature stability and transient performance of the electronic voltage transformer according to a capacitive voltage division principle are improved.

Description

Adopt the electronic type voltage transformer and the error calibrating method thereof of data fusion technology

Technical field

The present invention relates to a kind of electric system primary voltage measurement mechanism, this device adopts capacitive divider to obtain as voltage sensor can be for the small voltage signal of measuring, and by multiple Digital Signal Processings such as data fusion, output and tested primary voltage homophase, amplitude are proportional to the digital signal of tested primary voltage.

Background technology

Capacitance type potential transformer (being called for short CVT) is adopted in the voltage measurement of outdoor 110kV of tradition and above electric pressure mostly, and it mainly is made up of capacitive divider and electromagnetic unit, and as shown in Figure 5, capacitive divider comprises high-voltage arm capacitor C 1 and low-voltage arm capacitor C 2; Electromagnetic unit comprises intermediate transformer T, compensation reactor L, damper Zz and protection clearance G composition, and has loaded impedance Zf.Capacitance type potential transformer (CVT) is the electromagnetic type voltage transformer (VT) relatively, clear superiority such as have anti-ferroresonance, cost performance is higher and the operation maintenance workload is less, and the filter of its capacitive divider and trap binding energy double as carrier communication.

Intelligentized day by day substation secondary device needs voltage transformer (VT) that digitized voltage acquisition amount is provided, and no longer needs powerful input signal.Under this background, the electronic type voltage transformer technology has obtained tremendous development.All kinds of electronic type voltage transformer products based on optical principle, voltage divider principle etc. arise at the historic moment, and progressively introduce and obtained some engineerings to the market and use.Electronic mutual inductor based on capacitance partial pressure is developed by above-mentioned capacitance type potential transformer (CVT), owing to do not contain magnetic material, therefore is not subjected to the influence of saturated and hysteresis effect; The output of capacitive divider secondary voltage inserts data collection processor, has realized the digital collection and the output of voltage analog, satisfies intelligent substation to the voltage transformer (VT) technical requirement; And simple in structure, cheap for manufacturing cost, environmental protection more is main developing direction of electronic type voltage transformer product.

At present, adopt capacitive divider in practical engineering application, also to exist some problems to be solved as the electronic type voltage transformer of primary transducer.For example: atmospheric environment is to the influence of accuracy of measurement stability, the phase deviation of a sensing head output signal, and the transient characterisitics of electronic mutual inductor etc., above-mentioned factor has influenced applying of such electronic type voltage transformer to a certain extent.

Summary of the invention

Goal of the invention of the present invention is:

(1) eliminates or improve capacitive divider intrinsic standoff ratio temperature stability, make the electronic type voltage transformer ratio error in whole operating temperature range, satisfy of the requirement of GB/T 20840.7-2007 standard about accuracy.

(2) eliminate or improve the phase deviation that the calibrating signal transmission link causes, make the phase error of electronic type voltage transformer satisfy of the requirement of GB/T 20840.7-2007 standard about accuracy.

(3) to sample resistance R reasonable value, guarantee the electronic type voltage transformer transient performance, make it to satisfy GB/T 20840.7-2007 standard about requirements of transient performance.

(4) set up the error calibration system and the method for this electronic type voltage transformer.

For solving the problems of the technologies described above, the invention provides a kind of electronic type voltage transformer that adopts the capacitance partial pressure principle of multiple Digital Signal Processings such as data fusion technology, it is characterized in that, comprise primary voltage sensor (capacitive divider) and data collection processor, by resistance smaller sampling resistance from obtaining voltage sampling input data collection processor between intermediate voltage terminal of capacitive divider and low-voltage terminal, data collection processor connects temperature measurement system, the external environment condition that the collecting temperature measuring system is measured, the capacitive divider body, the temperature signal of data collection processor plate; Data collection processor is exported digitized primary voltage measured value by optical fiber interface after input signal is carried out data fusion.

The present invention also realizes by following further technical scheme:

(1) sets up primary transducer--the temperature model of capacitive divider of electronic type voltage transformer; And, in operational process, dynamically temperature variation and capacitive divider intrinsic standoff ratio are carried out data fusion according to this model.

(2) take into account the intrinsic phase deviation of signal transmission link, dynamic fusion signal frequency change information is calibrated phase deviation, improves the phase of output signal accuracy.

(3) analysis is calculated the sample resistance resistance to the specific requirement and the signal transmission network model of transient performance.

(4) make up error calibration system, calibrated error is also imported electronic type voltage transformer with control information, and foundation is provided for calibrating for error.

The beneficial effect that the present invention reached: this apparatus structure is simple, safe and practical, by data collection processor to capacitive divider secondary output voltage, information such as environment and voltage divider body temperature are carried out acquisition process, physical arrangement is simple, intelligent degree height, not only saved material, reduced manufacturing cost, and improved usability, meet the intelligent substation Developing Trend in Technology, digital convergence technology by a series of practicalities, when design to voltage divider secondary voltage sample resistance reasonable value, and in operational process, dynamically revise because temperature variation, the measuring error that factors such as signal transmission system cause makes electronic type voltage transformer have pin-point accuracy, advantages such as good transient performance and temperature stability.This electronic type voltage transformer is applicable to that the primary voltage of 110kV and above electric pressure electric system measures, and satisfies the requirement to aspects such as measuring voltage accuracy, transient performance of protecting electrical power system, measurement, measuring apparatus.The error calibration of electronic mutual inductor in manufacturing process finished by computer software by optical fiber interface, and needn't realize by adjusting the internal simulation circuit, improved production efficiency.After product is applied to engineering site, can under the situation of not cutting off the power supply, multiple control information be imported data collection processor by optical fiber interface,, realize the on-line error correction for the data fusion of outputting measurement value.Make field adjustable, operation become fool proof, convenient, fast.

Description of drawings

Fig. 1 adopts the principle of work synoptic diagram of the electronic type voltage transformer of data fusion technology for the present invention;

Fig. 2 is a data collection processor circuit diagram among Fig. 1;

Fig. 3 is the software flow block diagram of data collection processor among Fig. 1;

Fig. 4 is error calibration of the present invention and operation networking synoptic diagram;

Fig. 5 is a capacitance type potential transformer schematic diagram in the prior art.

Embodiment

Below in conjunction with accompanying drawing the present invention is further described.Following examples only are used for technical scheme of the present invention more clearly is described, and can not limit protection scope of the present invention with this.

As shown in Figure 1, the present invention adopts the electronic type voltage transformer of data fusion technology to comprise capacitive divider, temperature measurement system, data collection processor.Capacitive divider comprises: adopt the external insulation casing pipe of compound substance, high-voltage arm capacitor C 1 and low-voltage arm capacitor C 2, base and other gold utensil of film paper material to form.Insert the ac voltage input mouth of data collection processor behind intermediate voltage terminal of capacitive divider and low pressure (ground connection) the terminal cross-over connection secondary voltage sample resistance R.Temperature and resistance and other thermometric chip have been formed temp measuring system, and the thermometric information of temperature sensor is sent into the temperature signal input port of data collection processor.Also comprise collection of simulant signal and Data Fusion module in the data collection processor.Data collection processor digital quantity input/output port is connected with merge cells or debugging verification terminal by optical fiber interface.

In the present invention, disclose the method in a kind of intrinsic standoff ratio that dynamically temperature information is fused to capacitive divider, adopted digital processing method to realize the compensation correction of intrinsic standoff ratio.When voltage divider is unloaded among Fig. 1, intermediate voltage terminal output voltage U over the ground _SecFor:

$U_{\sec }=U_{\mathrm{pri}}\·\frac{C_1}{C_1+C_2}---\left(1\right)$

Wherein: U _PriBe tested primary voltage, C ₁Be high-voltage arm electric capacity, C ₂Be low-voltage arm electric capacity,

Intrinsic standoff ratio K for capacitive divider.

In order to realize less intrinsic standoff ratio, so that U _SecEnough little, can directly measure C for data collection processor ₂＞＞C ₁Thereby high-voltage arm capacitor C ₁With the low-voltage arm capacitor C ₂The structure that adopts when design has certain difference.Temperature variation can cause the variation of electric capacity usually, and the capacitor of different structure temperature coefficient generally speaking is also different, and the temperature coefficient of the capacitor of a fixed structure can calculate acquisition and pass through the actual measurement checking when design.To the definition of temperature coefficient, can be expressed as in the foundation " GB/T 19749-2005 coupling condenser and capacitive divider " through the revised intrinsic standoff ratio of excess temperature:

$K=\frac{C_{1T20}[1+k_1(T-20)]}{C_{1T20}[1+k_1(T-20)]+C_{2T20}[1+k_2(T-20)]}---\left(2\right)$

(2) in the formula: C _1T20, C _2T20Be respectively high pressure, the appearance value of low-voltage arm electric capacity in the time of 20 ℃; k ₁And k ₂Be respectively the temperature coefficient of above-mentioned electric capacity; The observed temperature of the voltage divider when T is operation.

Yet, the temperature T when electronic mutual inductor is carried out error calibration ₀Can it just not be 20 ℃.If the temperature coefficient of capacitor is k, at T ₀Following appearance value is C ₀, the appearance value C of capacitor in the time of 20 ℃ then _T20Can be expressed as:

$C_{T20}=\frac{C_0}{1+(T_0-20)k}---\left(3\right)$

According to defining of (3) formula and temperature coefficient:

$C=C_{T20}+C_{T20}(T-20)k=C_0+\frac{C_0(T-T_0)k}{1+(T_0-20)k}---\left(3a\right)$

Wherein, C is an appearance value under T.

Under present manufacture level, the temperature coefficient k of capacitive divider between limitting 15 ℃ greater than height, can reach 5 * 10 in the temperature lower bound ^-4/ ℃ below.So in the allowable temperature scope of mutual inductor operation (40 ℃～60 ℃), and according to (3a) formula, capacitance C can be approximately:

C＝≈C ₀+C ₀(T-T ₀)k (4)

By (4) formula and (2) Shi Kede:

$K=\frac{1}{1+\frac{C_{2T0}}{C_{1T0}}\·\frac{1+k_2\left({T-T}_0\right)}{1+k_1\left({T-T}_0\right)}}---\left(5\right)$

And: $\frac{C_{2T0}}{C_{1T0}}=\frac{1}{K_0}-1---\left(6\right)$

Wherein: C _1T0, C _2T0Be respectively high pressure, the temperature T of low-voltage arm electric capacity when error calibration ₀Under the appearance value,

K ₀Be T ₀The time capacitive divider that records intrinsic standoff ratio.

The temperature that can realize the intrinsic standoff ratio of capacitive divider by (5), (6) formula merges correction, guarantees its stability under different running temperatures.

In the present invention, disclose the method that compensation for calibrating errors is carried out in two kinds of phase deviations, adopted digital processing method to realize measured signal phase deviation correction.C among Fig. 1 ₁And C ₂Be two electric capacity of voltage divider, R is the equivalent input impedance of subsequent acquisition device.Can get following relational expression by circuit diagram:

$U_{\sec }=U_{\mathrm{pri}}\·\frac{\mathrm{j\ω}{\mathrm{RC}}_1+{\mathrm{\ω}}^2{R}^2{C}_1(C_1+C_2)}{1+{\mathrm{\ω}}^2{R}^2{(C_1+C_2)}^2}---\left(7\right)$

If tested secondary AC voltage: U _Sec(t)=U _mSin ω t; Wherein, U _mBe signal amplitude, ω is the signal angular frequency, and t is the time,

Then:

In the formula (8), A is the amplitude gain coefficient of voltage signal transmission network,

Phase deviation for the voltage signal transmission network.By (8) Shi Kede:

That is: the output of the signal behind the phase alignment can obtain through (9) formula computing with currency and the value before 1/4 cycle.For fixed sample rate f _sDiscrete system, establishing weekly the phase sampling number is k, (9) can be exchanged into following form:

Because the measured signal frequency f changes, so k is a variable, the present invention follows the tracks of the frequency f of measured signal, can get:

$k=\frac{f_s}{f}---\left(11\right)$

Have m, make: m≤n-k/4≤m+1 can get by linear interpolation:

U _sec(n-k/4)≈U _sec(m)+[U _sec(m+1)-U _sec(m)]·(n-k/4-m) (12)

Record at the transformer error timing signal, (12) formula substitution (10) formula is got U _Pri(n).

For the calibration of leading phase skew, adopted another kind of calibration steps: the dynamic fusion signal frequency is with leading phase deviation

Being converted into the leading time is T _d,, sampled value need be postponed T in order to calibrate leading phase place _dOutput, establishing the ADC sampling interval is T _s, T then _dCan be expressed as following formula:

The meaning of following formula is: at sampling interval T _sΔ T is constantly to signal sampling in interval, and exports this sampled value after n sampling interval, can calibrate the leading phase deviation of measured signal.

In the present invention, disclosed a kind of method to the sample resistance value.In the GB/T 20840.7-2007 standard: for the electronic type voltage transformer of pure capacitive divider, if be peak value at primary voltage as high pressure sensor

Insantaneous break circuit (other relative ground circuit), exist again

Instantaneous (its symbol be detained the opposite of electric charge) reclosing, the following parametric description of its transient condition:

T≤0 o'clock: U _p=0; $U_{\mathrm{pdc}}=\±k_u\·U_{\mathrm{pn}}\sqrt{2}---\left(14\right)$

T＞0 o'clock: U _p=U _PnU _pBy=0 (15)

The transient error definition: ${\mathrm{\ϵ}}_u\left(t\right)\%=\frac{K_n\·u_s\left(t\right)-u_p\left(t\right)}{U_p\sqrt{2}}\·100\%---\left(16\right)$

(14)-(16) in the formula:

U _pRoot-mean-square value for the primary voltage power frequency;

U _PdcIt is a DC voltage;

k _uBe rated voltage factor;

U _PnBe U _pRatings;

ε _u(t) be the voltage error instantaneous value;

K _nBe the mutual inductor nominal transformation ratio;

u _p(t), u _s(t), be respectively once, the instantaneous value of secondary voltage.

At the moment of reclosing t=0 ⁺, be trapped in C ₁On electric charge through almost whole (because the C of electric power loop ₂＞＞C ₁, both differ about 4 orders of magnitude) and transfer to C ₂, at C ₂The initial DC voltage component U of last generation _Sde:

$u_{\mathrm{sdc}}=\frac{k_u}{K_n}\·U_{\mathrm{pn}}\sqrt{2}---\left(17\right)$

C ₂By sample resistance R discharge, the secondary voltage instantaneous value can be expressed as:

$u_s\left(t\right)=\frac{1}{K_n}[u_p\left(t\right)+k_u\·U_{\mathrm{pn}}\sqrt{2}\·e^{-\frac{t}{\mathrm{\τ}}}],\mathrm{\τ}={\mathrm{RC}}_2---\left(18\right)$

By (15), (17), (18) formula, transient error is: ${\mathrm{\ϵ}}_u\left(t\right)\%=k_u\·e^{-\frac{t}{{\mathrm{RC}}_2}}\·100\%---\left(19\right)$

Press GB/T 20840.7-2007 standard, under power frequency 50Hz, need to satisfy simultaneously:

ε _u(t)＜10 ^a，0.04s＜t≤0.06s (20)

ε _u(t)＜5 ^a，0.06s＜t≤0.08s，0.1s (21)

Wherein, a: can be by user's actual needs value.A can be by following table definition, and following table is selected from the GB/T20840.7-2007 standard

The instantaneous voltage error limit value of electric charge reclosing is detained in protection at band with electronic type voltage transformer

Ft is the product of frequency f and time t in the last table

By: (19), (20), (21) formula get:

$R\≤\frac{0.04}{C_2\·\ln \frac{k_u}{{10}^{a-2}}},$ And $R\≤\frac{0.06}{C_2\·\ln \frac{k_u}{5^{a-2}}}---\left(22\right)$

According to (22) formula, can obtain the value upper limit of sample resistance R.

As shown in Figure 2; data collection processor comprises successively the ADC analog-to-digital conversion module of the analog quantity input that is electrically connected and protection module, sampled signal modulate circuit, double copies; also comprise the switching value input circuit, switching value output circuit, simulated measurement input circuit, storer, communication interface circuit, the power supply that are connected with central processing unit, the ACD analog-to-digital conversion module also is connected with central processing unit.Analog quantity input and protection module receive the primary voltage sampled signal of capacitive divider and the temperature signal of temperature sensor transmission, and overvoltage protection is provided.The sampled signal modulate circuit is adjusted the amplitude and the phase place of input signal, and anti-aliasing filter.The ADC analog-to-digital conversion module is accepted the sampling pulse from central processing unit, to sampling from the signal of sampled signal modulate circuit and analog to digital conversion and the result sent into central processing unit by SPI1, SPI2 interface.Frequency measurement circuit is made up of frequency tracking circuit and frequency measurement passage, monitors its output square-wave signal by the GPIO interface, realizes the frequency-tracking function of signal.The plate temperature is measured by the plate temperature element, sends into central processing unit through the I2C interface.Data acquisition process software by optical fiber interface, is exported digitized primary voltage measured value by the synchronized sampling beat after various input informations and voltage acquisition amount are merged.The parameter memory element is used for the error calibration parameter of store electricity minor mutual inductor; The recording storage element is used for the storage running state recording; Interfaces such as the WATCHDOG, the DEBUG that are used for self check, maintenance and switching value input and output have been disposed in addition.

As shown in Figure 3, data acquisition process software mainly is made up of master routine circulation and system timer interruption, the subroutines such as interruption, UASRTDMA interruption, TIM, TIM2 interruption of sampling.Major cycle carries out System self-test and the above-mentioned interruption of initialization when powerup/reset, from EEPROM reading error calibrating parameters; Foundation 5,6,9,12,13 circular treatment temperature, the data fusion information that signal frequency is relevant; At any time prepare to handle calibration maintenance information from the outside.System timer interrupts producing the system clock beat, receives the data from DEBUGUASRT.Data collection processor is received from producing sampling behind the sampling pulse of merge cells and is interrupted, carry out that adc data reads, frequency-tracking, finish fusion correction, the buffer memory sampled data of sampled data and trigger that sampled data sends USARTDMA and TIM2 is interrupted in the time-delay sampling.USARTDMA interrupts realizing need not the data transmission that central processing unit is intervened.TIM2 triggers the ADC sampling, can change the moment of triggering TIM2 by dynamic adjustments TIM parameter, thereby changes the sampling instant Δ T of ADC, realizes the fine setting of output sampled data phase place.

As shown in Figure 4, the present invention adopts the electronic type voltage transformer of data fusion technology to be used for intelligent substation, connects and composes intelligent substation process layer voltage measurement system with merge cells (MU).Merge cells connection procedure layer Ethernet switch adopts the sampled value information such as subscriber bay device issue primary voltage of IEC61850-9-2 standard to data.Electronic type voltage transformer safeguards that calibration operation can be divided into two kinds of situations: in the factory and on-the-spot, in factory, safeguard and during error calibration, merge cells connects simultaneously by school electronic type voltage transformer and standard potential transformer, maintenance work station connection procedure layer Ethernet switch, by once pressurization, on the maintenance work station, two-way is carried out the Error Calculation comparison from the voltage sample value of the IEC61850-9-2 of merge cells, error calibration and maintenance information are adorned down by the DEBUG interface of data collection processor.As long as there is normative reference, can carry out on-line maintenance and error calibration safely at the electronic type voltage transformer of fortune to the scene, from the error calibration at maintenance work station and maintenance information via process layer Ethernet switch, (MU) installs to electronic type voltage transformer by under the optical fiber interface by merge cells, realization has realized the isolation of high pressure, low pressure guaranteeing the security of safeguarding by optical fiber communication.

The above only is a preferred implementation of the present invention; should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the technology of the present invention principle; can also make some improvement and distortion, these improvement and distortion also should be considered as protection scope of the present invention.

Claims (8)

1. electronic type voltage transformer that adopts the data fusion technology, it is characterized in that, the capacitive divider and the data collection processor that comprise the primary voltage sensor side, by resistance smaller sampling resistance from obtaining voltage sampling input data collection processor between intermediate voltage terminal of capacitive divider and low-voltage terminal, data collection processor connects temperature measurement system, the temperature signal of the external environment condition that the collecting temperature measuring system is measured, capacitive divider body, data collection processor plate; Data collection processor is exported digitized primary voltage measured value by optical fiber interface after input signal is carried out data fusion.

2. the electronic type voltage transformer of employing data fusion technology according to claim 1; it is characterized in that; data collection processor comprises successively the ADC analog-to-digital conversion module of the analog quantity input that is electrically connected and protection module, sampled signal modulate circuit, double copies; also comprise the switching value input circuit, switching value output circuit, simulated measurement input circuit, storer, communication interface circuit, the power supply that are connected with central processing unit, the ACD analog-to-digital conversion module also is connected with central processing unit.

3. to the error calibrating method of the electronic type voltage transformer of the described employing data fusion of claim 1 technology, it is characterized in that the process of measuring primary voltage is:

(1) obtains the tested voltage of secondary by capacitive divider and sample resistance R, this voltage is inserted the data collection processor sampling and follows the tracks of its frequency; The signal that will be installed on the temperature sensor of capacitive divider body, mutual inductor base, data collection processor plate simultaneously inserts data collection processor, calculates each measuring point temperature.

(2) by the data acquisition unit process software according to the measuring point temperature variation, dynamic calculation capacitive divider intrinsic standoff ratio, thus revise the mutual inductor ratio error.

(3) by data acquisition unit process software basis signal frequency change, the mutual inductor phase error is revised in the phase deviation that links such as dynamic calculation primary voltage sensor, sampled signal conditioning produce signal.

(4) export the digitized sampling value that is proportional to tested voltage with primary measured voltage same-phase, amplitude by optical fiber interface.

4. the error calibrating method of the electronic type voltage transformer of employing data fusion technology according to claim 3 is characterized in that, capacitive divider comprises the high voltage arm capacitor C of series connection ₁With low-voltage arm capacitor C ₂, C ₂＞＞C ₁, low-voltage arm capacitor C ₂And meeting secondary voltage sample resistance R, the secondary voltage that sample resistance R goes up output inserts data collection processor.

5. the error calibrating method of the electronic type voltage transformer of employing data fusion technology according to claim 4, it is characterized in that: according to the temperature coefficient of capacitor, set up the temperature model of capacitive divider intrinsic standoff ratio, dynamically temperature information is fused to the method in the intrinsic standoff ratio of capacitive divider, adopt digital processing method to realize the compensation correction of intrinsic standoff ratio, concrete steps are as follows:

When capacitive divider is unloaded, intermediate voltage terminal output voltage U over the ground _SecFor:

$U_{\sec }=U_{\mathrm{pri}}\·\frac{C_1}{C_1+C_2}---\left(1\right)$

Wherein: U _PriBe tested primary voltage, C ₁Be high-voltage arm electric capacity, C ₂Be low-voltage arm electric capacity,

Intrinsic standoff ratio K for capacitive divider;

Because C ₂＞＞C ₁And temperature variation can cause the variation of electric capacity usually; the capacitor of different structure temperature coefficient generally speaking is also different; the temperature coefficient of the capacitor of one fixed structure can calculate acquisition and pass through the actual measurement checking when design; definition according to temperature coefficient can be expressed as through the revised intrinsic standoff ratio of excess temperature:

$K=\frac{C_{1T20}[1+k_1(T-20)]}{C_{1T20}[1+k_1(T-20)]+C_{2T20}[1+k_2(T-20)]}---\left(2\right)$

(2) in the formula: C _1T20, C _2T20Be respectively high pressure, the appearance value of low-voltage arm electric capacity in the time of 20 ℃; k ₁And k ₂Be respectively the temperature coefficient of above-mentioned electric capacity; The observed temperature of the voltage divider when T is operation;

In the reality, the temperature T when electronic mutual inductor is carried out error calibration ₀Can be not 20 ℃ just, the temperature coefficient of establishing capacitor be k, at T ₀Following appearance value is C ₀, the appearance value C of capacitor in the time of 20 ℃ then _T20Can be expressed as:

$C_{T20}=\frac{C_0}{1+(T_0-20)k}---\left(3\right)$

According to defining of (3) formula and temperature coefficient:

$C=C_{T20}+C_{T20}(T-20)k=C_0+\frac{C_0(T-T_0)k}{1+(T_0-20)k}---\left(3a\right)$

Wherein, C is an appearance value under T.

Under present manufacture level, the temperature coefficient k of capacitive divider between limitting 15 ℃ greater than height, can reach 5 * 10 in the temperature lower bound ^-4/ ℃ below, in the allowable temperature scope-40 of mutual inductor operation ℃～60 ℃, and according to (3a) formula, capacitance C can be approximately:

C＝C ₀+C ₀(T-T ₀)k (4)

By (4) formula and (2) Shi Kede:

$K=\frac{1}{1+\frac{C_{2T0}}{C_{1T0}}\·\frac{1+k_2\left({T-T}_0\right)}{1+k_1\left({T-T}_0\right)}}---\left(5\right)$

And: $\frac{C_{2T0}}{C_{1T0}}=\frac{1}{K_0}-1---\left(6\right)$

Wherein: C _1T0, C _2T0Be respectively high pressure, the temperature T of low-voltage arm electric capacity when error calibration ₀Under the appearance value, K ₀T during for error calibration ₀The intrinsic standoff ratio of the capacitive divider that records during error calibration under the temperature;

The temperature that can realize the intrinsic standoff ratio of capacitive divider by (5), (6) formula merges correction.

6. the error calibrating method of the electronic type voltage transformer of employing data fusion technology according to claim 4 is characterized in that: by the phase deviation of digital processing method correction measured signal, C ₁And C ₂Be two electric capacity of voltage divider, R is the equivalent input impedance of subsequent acquisition device, secondary voltage U _SecWith primary voltage U _PriRelational expression is as follows:

$U_{\sec }=U_{\mathrm{pri}}\·\frac{\mathrm{j\ω}{\mathrm{RC}}_1+{\mathrm{\ω}}^2{R}^2{C}_1(C_1+C_2)}{1+{\mathrm{\ω}}^2{R}^2{(C_1+C_2)}^2}---\left(7\right)$

If tested secondary AC voltage: U _Sec(t)=U _mSin ω t; Wherein, U _mBe signal amplitude, ω is the signal angular frequency, and t is the time,

Then:

In the formula (8), A is the amplitude gain coefficient of voltage signal transmission network,

Phase deviation for the voltage signal transmission network.By (8) Shi Kede:

That is: the output of the signal behind the phase alignment can obtain through (9) formula computing with currency and the value before 1/4 cycle.For fixed sample rate f _sDiscrete system, establishing weekly the phase sampling number is k, (9) can be exchanged into following form:

Because the measured signal frequency f changes, so k is a variable, the present invention follows the tracks of the frequency f of measured signal, can get:

$k=\frac{f_s}{f}---\left(11\right)$

Have m, make: m≤n-k/4≤m+1 can get by linear interpolation:

U _sec(n-k/4)≈U _sec(m)+[U _sec(m+1)-U _sec(m)]·(n-k/4-m) (12)

Record at the transformer error timing signal, (12) formula substitution (10) formula is got U _Pri(n).

7. the error calibrating method of the electronic type voltage transformer of employing data fusion technology according to claim 3, it is characterized in that: adopt the phase deviation of the calibration steps correction measured signal of leading phase skew, the dynamic fusion signal frequency is with leading phase deviation

Being converted into the leading time is T _d,, sampled value need be postponed T in order to calibrate leading phase place _dOutput, establishing the ADC sampling interval is T _s, T then _dCan be expressed as following formula:

The meaning of following formula is: at sampling interval T _sΔ T is constantly to signal sampling in interval, and exports this sampled value after n sampling interval, can calibrate the leading phase deviation of measured signal.

8. the error calibrating method of the electronic type voltage transformer of employing data fusion technology according to claim 3, it is characterized in that: the value computing method of sample resistance R realize as follows, by reasonable value the transient performance of being detained in the electric charge reclosing process at band is met the demands to R, (1) is used in the transient condition definition, and (2) formula is described: the following parametric description of transient condition:

T≤0 o'clock: U _p=0; $U_{\mathrm{pdc}}=\±k_u\·U_{\mathrm{pn}}\sqrt{2}---\left(14\right)$

T＞0 o'clock: U _p=U _PnU _pBy=0 (15)

The transient error definition: ${\mathrm{\ϵ}}_u\left(t\right)\%=\frac{K_n\·u_s\left(t\right)-u_p\left(t\right)}{U_p\sqrt{2}}\·100\%---\left(16\right)$

(14)-(16) in the formula:

U _pRoot-mean-square value for the primary voltage power frequency;

U _PdcIt is a DC voltage;

k _uBe rated voltage factor;

U _PnBe U _pRatings;

ε _u(t) be the voltage error instantaneous value;

K _nBe the mutual inductor nominal transformation ratio;

u _p(t), u _s(t), be respectively once, the instantaneous value of secondary voltage.

At the moment of reclosing t=0 ⁺, be trapped in C ₁On electric charge almost all transfer to C through electric power loop ₂, at C ₂The initial DC voltage component U of last generation _Sdc:

$u_{\mathrm{sdc}}=\frac{k_u}{K_n}\·U_{\mathrm{pn}}\sqrt{2}---\left(17\right)$

Transfer to C ₂The delay electric charge discharge by sample resistance R, the secondary voltage instantaneous value on the R can be expressed as:

$u_s\left(t\right)=\frac{1}{K_n}[u_p\left(t\right)+k_u\·U_{\mathrm{pn}}\sqrt{2}\·e^{-\frac{t}{\mathrm{\τ}}}],\mathrm{\τ}={\mathrm{RC}}_2---\left(18\right)$

By (15), (17), (18) formula, transient error is:

${\mathrm{\ϵ}}_u\left(t\right)\%=k_u\·e^{-\frac{t}{{\mathrm{RC}}_2}}\·100\%---\left(19\right)$

Under power frequency 50Hz, need to satisfy simultaneously:

ε _u(t)＜10 ^a，0.04s＜t≤0.06s (20)

ε _u(t)＜5 ^a，0.06s＜t≤0.08s，0.1s (21)

Wherein, a: can be by user's actual needs value.

By: (19), (20), (21) formula obtain the inequality about R:

$R\≤\frac{0.04}{C_2\·\ln \frac{k_u}{{10}^{a-2}}},$ And $R\≤\frac{0.06}{C_2\·\ln \frac{k_u}{5^{a-2}}}---\left(22\right)$

According to (22) formula, can obtain the value upper limit of sample resistance R.

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