CN109782206B - Calibration compensation method for broadband transient voltage measuring device - Google Patents
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Abstract
The invention discloses a calibration compensation method for a broadband transient voltage measuring device, which comprises the following steps: calibrating the broadband transient voltage measuring device, and establishing an output error model; establishing a digital compensation model based on the output error model; evaluating the measurement error compensated by the digital compensation model; and carrying out digital compensation on the output waveform of the broadband transient voltage measuring device. The invention fully considers the influence of stray parameters existing in the actual installation site on the transmission characteristics of the broadband transient voltage measuring device, carries out site calibration on the transient voltage measuring device, and compensates the inherent frequency transmission defect of the measuring device in a broadband range by carrying out digital compensation on the output waveform, thereby truly restoring the waveform characteristics of the input transient voltage, and having high stability and reliability and simple operation.
Description
Technical Field
The present invention relates to high voltage technology and measurement technology, and more particularly, to a calibration compensation method for a broadband transient voltage measurement device.
Background
With the development of power transmission technology, the safe operation of the power grid is more and more emphasized. The simulation calculation and the field actual measurement of the transient voltage of the power grid are the main means for researching the insulation coordination of the system, equipment fault diagnosis and accident cause analysis at present; the actually measured transient voltage is the primary basis for verifying the simulation calculation conclusion of the transient voltage, so that the accurate measurement of the transient overvoltage has great significance for the safety guarantee of the operation of the power grid.
The transient voltage waveform is complex, the frequency components are rich, and the transfer characteristic of the transient voltage measuring device under the action of the transient voltage needs to be comprehensively evaluated to accurately obtain the waveform. However, stray parameters exist between the transient voltage measuring device and surrounding objects after field installation, so that the actual transfer characteristics of the transient voltage measuring device are different from laboratory calibration results, and errors exist between the output waveform and the input waveform of the transient voltage measuring device. Therefore, it is necessary to perform field calibration on the installed transient voltage measurement device under actual conditions, analyze the transmission error of the transient voltage measurement device, complete actual compensation on the secondary-side output waveform, and restore the real primary-side input waveform.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to fully consider the influence of stray parameters existing in an actual installation site on the transmission characteristics of the broadband transient voltage measuring device, carry out site calibration on the transient voltage measuring device, and compensate the inherent frequency transmission defect of the measuring device in a broadband range by carrying out digital compensation on an output waveform, thereby truly restoring the waveform characteristics of the input transient voltage.
In order to achieve the above object, the present invention provides a calibration compensation method for a broadband transient voltage measurement apparatus, including:
calibrating the broadband transient voltage measuring device, and establishing an output error model;
establishing a digital compensation model based on the output error model;
evaluating the measurement error compensated by the digital compensation model;
and when the measurement error meets the requirement, performing digital compensation on the output waveform of the broadband transient voltage measurement device according to the digital compensation model.
Further, the calibrating the broadband transient voltage measuring device and establishing an output error model includes:
acquiring the output of a standard voltage source passing through a standard measurement system;
acquiring the output of the standard voltage source through the broadband transient voltage measuring device;
taking the broadband transient voltage measuring device as a two-port passive network, and establishing the output error model by a mathematical analysis method;
solving the output error model parameters based on a system identification technology;
and acquiring the transfer characteristic of the broadband transient voltage detection device.
Further, the output error model expression is:
wherein y (t) is the output of the reference voltage source through the reference measurement system;
x (t) is the output of the standard voltage source through the broadband transient voltage measurement device;
q is a time shift operator, q-kx (i Δ t) ═ x ((i-k) Δ t), Δ t is the sampling interval;
A(q)＝1+a1q-1+a2q-2+…+am-1q-(m-1)+amq-m；
B(q)＝b0+b1q-1+b2q-2+…+bn-1q-(n-1)+bnq-n；
e (t) is the output error vector of the broadband transient voltage measurement device.
Solving parameter a based on system identification technologyi、biAnd the time domain and frequency domain transfer characteristics of the broadband transient voltage measuring device can be obtained.
Furthermore, the amplitude fluctuation range of the standard voltage source is less than 1%, the frequency range reaches nanosecond level, and the frequency component of the output voltage covers the frequency range of the measured broadband transient voltage.
Preferably, the standard voltage source adopts an impulse voltage source or a sinusoidal alternating voltage source with adjustable frequency and broadband.
Furthermore, the standard measurement system meets the requirements of the standard measurement system in the national standard GB/T16992 7, and can meet better frequency transfer characteristics in a wide frequency range.
Preferably, the standard measurement system employs a resistive-capacitive high voltage divider.
Further, the standard measurement system should ensure that the transfer characteristic of the broadband transient voltage measurement system is not greatly affected.
Further, the establishing a digital compensation model based on the output error model includes:
taking the output of the standard voltage source through the broadband transient voltage measuring device as the input to be compensated of the digital compensation model;
taking the output of the standard voltage source passing through the standard measurement system as the expected output after the digital compensation model is compensated;
establishing the digital compensation model by a mathematical analysis method;
and solving the parameters of the digital compensation model based on a system identification technology.
The expression of the digital compensation model is as follows:
in the formula, y*(t) is output after compensation; y (t) is the output to be compensated; e (t) is an error term.
C(q-1)＝1+c1q-1+c2q-2+…+ck-1q-(k-1)+ckq-k；
D(q-1)＝d0+d1q-1+b2q-2+…+dl-1q-(l-1)+dlq-l；
Taking y (t) as the output to be compensated, taking x (t) as the output after compensation, and reversely solving the model parameters and the parameters ci、diMethod for solving (1) and parameter (a)i、biThe same is true.
Further, the estimation of the measurement error compensated by the digital compensation model is performed by the formula:
FIT 100 x (1-norm (Y-YHAT)/norm (Y-mean) (Y)), Y is the desired output, YHAT is the compensated output, norm is a two-norm function, norm (x) represents the sum of the squares of each element in x followed by the root number, mean is the mean function, and mean (x) represents the number of elements divided by the sum of each element in x.
And when the difference between the amplitude of the expected output and the amplitude of the compensated output is not more than 3%, and the calculated FIT value is more than 99, the measurement error is considered to meet the requirement, namely the digital compensation model is valid.
Further, the digitally compensating the output waveform of the broadband transient voltage measurement device according to the digital compensation model includes:
establishing a submodule of the digital compensation model;
acquiring the output of the broadband transient voltage through the broadband transient voltage measuring device;
and accessing the output to the submodule through a data conversion interface.
And outputting the compensated waveform.
In general, the technical scheme of the invention can achieve the following beneficial effects:
(1) through field calibration, an error output model is established, the influence of stray factors existing in a field environment on the transfer characteristics of the measuring device is fully considered, and the measuring error of the measuring device after field installation can be accurately evaluated.
(2) The digital compensation technology is adopted, the inherent frequency transmission defect of the measuring device in a wide frequency range is overcome, the stability and the reliability are high, the operation is convenient, and the transient voltage waveform on the primary side can be truly restored.
Drawings
FIG. 1 is a flow chart of a calibration compensation method for a broadband transient voltage measurement device according to the present invention;
FIG. 2 is a schematic diagram of a calibration layout for a broadband transient voltage measurement device according to the present invention;
FIG. 3 is a schematic diagram of a digital compensation operation for a broadband transient voltage measurement device according to the present invention;
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Fig. 1 is a flowchart of a calibration compensation method for a broadband transient voltage measurement device according to the present invention, comprising the following steps:
s101: calibrating the broadband transient voltage measuring device, and establishing an output error model;
specifically, the steps include:
acquiring the output of a standard voltage source passing through a standard measurement system;
acquiring the output of the standard voltage source through the broadband transient voltage measuring device;
taking the broadband transient voltage measuring device as a two-port passive network, and establishing the output error model by a mathematical analysis method;
solving the output error model parameters based on a system identification technology;
and acquiring the transfer characteristic of the broadband transient voltage detection device.
Fig. 2 is a schematic layout of a calibration method applying the present invention, as shown in fig. 2, during field calibration, the method includes: a standard voltage source, a broadband transient voltage standard measurement system and a broadband transient voltage detection device;
the broadband transient voltage standard measurement system and the broadband transient voltage measurement device are connected in parallel, and a standard voltage source is used as the common input of the broadband transient voltage standard measurement system and the broadband transient voltage measurement device.
It should be noted that the access of the standard measurement system should ensure that the transfer characteristic of the transient voltage measurement device is not greatly affected, i.e. the transfer characteristic of the broadband transient voltage measurement device does not vary by more than 1%. (ii) a The amplitude fluctuation range of the standard voltage source is less than 1%, the frequency range reaches nanosecond level, the frequency component of the output voltage covers the frequency range of the broadband transient voltage, and an impact voltage source or a frequency-adjustable broadband sine alternating voltage source can be selected; the standard measurement system meets the accuracy requirement of the standard measurement system in the national standard GB/T16992 7, can meet better frequency transfer characteristics in a wide frequency range, and can generally adopt a resistance-capacitance type high-voltage divider.
The output of the transient voltage standard measurement system is denoted as x (t), and the output of the transient voltage measurement device is denoted as y (t).
The transition frequency in the transfer characteristic of the broadband transient voltage measuring device is such that there is a certain deviation between y (t) and x (t), and to compensate the distorted output waveform y (t), the transfer characteristic of the broadband transient voltage measuring device after field installation should be analyzed first to establish an output error model.
The broadband transient voltage measuring device is considered as a two-port passive network, and an output error model can be established through data discretization treatment:
in the formula (1), q is a time shift operator, q-kx (i Δ t) ═ x ((i-k) Δ t), Δ t is the sampling interval;
e (t) is the output error vector of the broadband transient voltage measurement device.
A(q)＝1+a1q-1+a2q-2+…+am-1q-(m-1)+amq-m；
B(q)＝b0+b1q-1+b2q-2+…+bn-1q-(n-1)+bnq-n；
Parameter ai、biReflecting the time domain characteristics of the transient voltage measuring device, the formula (1) can be converted into a frequency domain discretization transfer function model of the broadband transient voltage measuring device:
wherein A (z) ═ 1+ a1z-1+a2z-2+…+am-1z-(m-1)+amz-m；
B(z)＝b0+b1z-1+b2z-2+…+bn-1z-(n-1)+bnz-n。
Parameter ai、biCalculating the parameter a by using a parameter extraction algorithm based on a system identification technology through a Matlab programi、biThe time domain and frequency domain transfer characteristics of the broadband transient voltage measuring device can be obtained, and the sensitivity and the turning frequency of different frequency bands can be obtained from the transfer characteristics, so that data support is provided for subsequent digital compensation.
S102: establishing a digital compensation model based on the output error model;
specifically, the steps include:
taking the output of the standard voltage source through the broadband transient voltage measuring device as the input to be compensated of the digital compensation model;
taking the output of the standard voltage source passing through the standard measurement system as the expected output after the digital compensation model is compensated;
establishing the digital compensation model by a mathematical analysis method;
and solving the parameters of the digital compensation model based on a system identification technology.
The form of the digital compensation model is the same as the output error model:
in the formula, y*(t) is output after compensation; y (t) is the output to be compensated; e (t) is an error term.
C(q-1)＝1+c1q-1+c2q-2+…+ck-1q-(k-1)+ckq-k；
D(q-1)＝d0+d1q-1+b2q-2+…+dl-1q-(l-1)+dlq-l；
Taking y (t) as the output to be compensated, taking x (t) as the output after compensation, and reversely solving the model parameters and the parameters ci、diMethod for solving (1) and parameter (a)i、biThe same is true.
S103: evaluating the measurement error compensated by the digital compensation model;
specifically, whether the measurement error in this step meets the requirement can be determined by the formula:
FIT (100) (1-norm (Y-YHAT)/norm (Y-mean (Y)));
equation, Y is the desired output, YHAT is the compensated output, norm is a two-norm function, norm (x) represents the sum of the squares of each element in x and the root, mean is the mean function, and mean (x) represents the number of elements divided by the sum of each element in x.
When the difference between the amplitude of the expected output and the amplitude of the compensated output is not more than 3%, and the calculated FIT value is more than 99, the measurement error is considered to meet the requirement, namely the digital compensation model is effective.
S104: carrying out digital compensation on the output waveform of the broadband transient voltage measuring device according to the digital compensation model;
specifically, the steps include:
establishing a submodule of the digital compensation model through MATLAB programming;
acquiring the output of the broadband transient voltage through a broadband transient voltage measuring device;
as shown in fig. 3: and directly accessing the output to a submodule of a digital compensation model through a data conversion interface, compensating the output waveform, and outputting the waveform after the reduction of the loss frequency component is completed.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (7)
1. A calibration compensation method for a broadband transient voltage measurement device, comprising:
calibrating the broadband transient voltage measuring device, and establishing an output error model; the output error model is solved by using a time domain signal to represent the measurement error of the broadband transient voltage measurement device in the time domain;
establishing a digital compensation model based on the output error model; the digital compensation model is solved by using a time domain signal, and the output of the broadband transient voltage measuring device is compensated in a time domain;
evaluating the measurement error compensated by the digital compensation model;
when the measurement error meets the requirement, digitally compensating the output waveform of the broadband transient voltage measurement device according to the digital compensation model;
wherein, the calibrating the broadband transient voltage measuring device and establishing an output error model comprises:
acquiring the output of a standard voltage source passing through a standard measurement system;
acquiring the output of the standard voltage source through the broadband transient voltage measuring device;
taking the broadband transient voltage measuring device as a two-port passive network, and establishing the output error model by a mathematical analysis method;
solving the output error model parameters based on a system identification technology;
acquiring the transfer characteristic of the broadband transient voltage detection device;
the establishing of the digital compensation model based on the output error model comprises the following steps:
taking the output of the standard voltage source through the broadband transient voltage measuring device as the input to be compensated of the digital compensation model;
taking the output of the standard voltage source passing through the standard measurement system as the expected output after the digital compensation model is compensated;
establishing the digital compensation model by a mathematical analysis method;
and solving the parameters of the digital compensation model based on a system identification technology.
2. The method of claim 1, wherein the amplitude fluctuation range of the reference voltage source is less than 1%, the frequency range reaches nanosecond level, and the frequency component of the output voltage covers the frequency range of the measured broadband transient voltage.
3. The method as claimed in claim 2, wherein the standard voltage source is an impulse voltage source or a frequency-tunable and broadband sinusoidal alternating voltage source.
4. The method as claimed in claim 1, wherein the standard measurement system meets the requirements of the standard measurement system in the national standard GB/T16992.
5. The method of claim 4, wherein the standard measurement system employs a RC high voltage divider.
6. The calibration compensation method for broadband transient voltage measurement device according to claim 1, wherein the estimation of the measurement error compensated by the digital compensation model is implemented by the formula FIT-100 ═ 1-norm (Y-YHAT)/norm (Y-mean (Y));
y is the expected output after compensation, YHAT is the actual output after compensation by the digital compensation model, norm is a two-norm function, norm (x) represents the square sum of each element in x and then the root number, mean is a mean function, mean (x) represents the number of elements divided by the sum of each element in x;
the difference between the compensated expected output and the compensated actual output amplitude is not more than 3%, and the calculated FIT value is more than 99, so that the measurement error is considered to meet the requirement.
7. The method of claim 1, wherein the digitally compensating the output waveform of the broadband transient voltage measurement device according to the digital compensation model comprises:
establishing a submodule of the digital compensation model;
acquiring the output of the broadband transient voltage through the broadband transient voltage measuring device;
the output of the broadband transient voltage measuring device is connected to the sub-module through a data conversion interface;
and outputting the compensated waveform.
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| CN111913023B (en) * | 2020-07-09 | 2021-07-27 | 华中科技大学 | Method and system for reducing accumulated errors of compensation model of capacitor voltage transformer |
| CN111983288A (en) * | 2020-08-17 | 2020-11-24 | 国网河南省电力公司电力科学研究院 | Voltage test system and method for high-voltage power equipment |
| CN112485509B (en) * | 2020-12-09 | 2023-10-31 | 国网四川省电力公司电力科学研究院 | Transient overvoltage measuring device and method based on nonlinear broadband model |
| CN112327243B (en) * | 2020-12-31 | 2021-04-02 | 中国电力科学研究院有限公司 | Self-calibration acquisition method and system of electric signals |
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