SU1474568A1 - Method and apparatus for automatic monitoring of power quality tester - Google Patents

Abstract

The invention relates to electrical measuring and electronic computing equipment. The purpose of the invention is to improve the accuracy and performance of calibrating dissimilar devices. The input signal (BC) is fed to the device being turned on 12, and the readings from the telemetric output of the latter and the pointer are taken and compared with the set values. In this case, BCs are formed using the piecewise linear approximation method, and the verification modes are programmed from the console 2 operators. In order to implement these modes, the slope coefficients of the segments approximating the aircraft and the duration of sampling intervals are changed according to a predetermined law depending on the device to be tested 12. The device for implementing the method contains a display unit 1, a print unit 3, an external memory block 4, an analog block 9 -digital converter. In addition, the device includes a microcomputer 5, an interface 6, a block of voltage shaping 7 of a piecewise linear shape, a block 8 of timers, a block 10 of large-scale amplifiers and a block 11 of switches, 2 s. and 5 hp f-ly, 2 ill.

Description

4 4

Ј

Sl

About 30

% 8.1

The invention relates to electrical measuring and computer technology and can be used to automate the calibration of means of monitoring. Indicators of power quality.

The aim of the invention is to improve the accuracy and performance of calibration of dissimilar devices

The essence of the method lies in the fact that the input signal is fed to the input of the scanned instrument, and from the tele-. The metric output of the device and the pointer take readings and compare

with given values.

Moreover, in order to increase the accuracy and productivity of the verification process, the input signal is formed using the piecewise linear approximation method, and the verification modes are programmed from the operator's console. To implement these modes, the slope coefficients, .ap-, which approximate the input signal and the duration discretization intervals according to a given law depending on the parameter being checked.

Figure 1 shows the block diagram of the device; Fig. 2 shows a piece of voltage forming piecewise linear form.

The device (Fig. 1) contains a display unit 1, an operator console 2, a printing unit 3, an external memory unit 4 connected to microcomputer 5, an interface 6 connected to a bi-directional communication with the microVM 5, a voltage shaping unit 7, piecewise linear whose first input is connected to the first output of interface 6, Timer unit 8 is connected bi-directionally to interface 6, its first output to control input of block 7 and interface 6, and the second output to interface 6 and control input of block 9 analog-to-digital converter that connect ene its output to the input interface unit 6. The scaling amplifier 10 is connected at its input to an output unit 7, and its output is connected to the analog input unit 11 switches. The control input of the latter is connected to the second output of the interface, the first output to the second input of block 9, and the second output to the connector for connecting the scanned device 12, the telemetric output of which is connected to the k input of block 8, Generator 13

five

g

O

five

0

0

. 5 40 5 -,

clock pulses connected by its output to the second input of block 8,

The device works as follows.

When powering up the microcomputer 5 initiates a dialogue with. the operator, who from the operator’s console 2 enters data specifying the type of instrument 12 being checked and the verification parameters, Microcomputer 5 calculates the test voltage characteristics (slope coefficients of the piecewise linear approximation, amplitude and frequency characteristics of the signal), programs the output in interface 6 and timers in block 8 of timers and, synchronized by signals of block 8 of timers, to which the clock pulses of a stable frequency from the generator of 13 clocks, sequentially outputs to the corresponding hell Port res in the interface 6 values of the slope coefficients of the generated alternating voltage curves (single or three phase) and the magnitude of the voltage amplitude 7 of the formation of a voltage of piecewise linear form and recorded in the second register 18 of block 7, from the output of which they go to the input of the code-current converter 16, where the analog signal is formed. full-time-constant cosine voltage corresponding coefficients of inclination. Further, this voltage is applied to the integrator 19, where it is converted into a sinusoidal piecewise linear voltage. A proportional change in the values of the slope coefficients is performed in block 14 by supplying a reference voltage for the code-current converter 16 through the first register 17 and the code-voltage converter 15. In this case, the amplitude of the formed signal varies.

To eliminate the drift of the integrator 19, it is reset when the sinusoidal voltage passes through a zero level. The reset is performed by a signal from the block of 8 timers to the analog switch 20, As a result, the generated alternating voltage with the specified characteristics of the input 147 large-scale amplifications to the input of the block 10

where it is amplified to the required value and fed to the input of the switch unit 11. At the beginning of the work on checking the device, unit 11 controls the output voltage of the microcomputer 5 via the interface 6 and switches the output voltage through the voltage divider of the unit 11 to the analog-digital converter unit 9, disconnecting the voltage from the connector of the device being tested. This is done for the purpose of self-checking of the installation and to ensure the safety of verification in case the installation is faulty. From block 9, the self-calibration signal codes through the interface 6 enter the microcomputer 5, where it is analyzed

if the installation is operational, yn

Hi

the equal signal from microcomputer 5 through interface 6 is fed to switch unit 11 and. The input voltage is connected to a test unit 12.

When a verification input voltage (single or three phase) is supplied to the device 12 with the specified power quality indicators, all current verification data is output to the display unit 1.

The results of a complete calibration of the instrument are displayed in block 1, printed in block 3, and recorded in block 4 of the external memory for further analysis and statistics.

Claims (6)

1. The method of automated calibration of means of monitoring power quality indicators by sending an input signal to the instrument being scanned, acting on the instrument pointer, recording the readings and automatically issuing the instrument calibration protocol, characterized in that, in order to improve the accuracy and enhance the verification capabilities, the input signal of the piecewise linear FR, the approximation period of which is divided into N, a multiple of 6 intervals, in each interval the coefficient C of the slope of the approximation segment is determined by formula fU-ati-flSi-UatJ Jt - -, i is the number of the approximation interval; - the duration of the interval approximation; with where At $ ten 20 25 thirty 35 0 five 0 five f is an approximated function, after which the input signal is formed, integrating a constant voltage, the value of which is proportional to С; on the i-th interval of approximation, 2. Method according to claim 1, characterized in that when calibrating harmonic meters the input signal is formed taking into account the spectral composition of the approximated function, while to determine St using the formula given, p .-, .. is the approximation function in Fourier series. given number of harmonics 3. Method pop.1, characterized in that when calibrating meters of asymmetry or about waveforms when forming the input signal, a third or a quarter of all coefficients of Cm are multiplied by the same number. 4. Method pop, 1, differs by the fact that when calibrating voltage fluctuation meters to generate an input signal, all С (is multiplied by the same coefficient, and its value in subsequent approximation periods changes with a given frequency 5. Method pop.1, characterized in that when calibrating the voltage frequency fluctuations meter when forming the input signal, the value of the approximation intervals, left unchanged within the approximation period, in subsequent periods is changed according to a given law, all C, change back to . is proportional to the change of intervals, approximation, in order to maintain a constant effective value of the input voltage, 6.A device for automated calibration of power quality control indicators, containing a microcomputer and connected there is a display unit, an operator panel, a printing unit, an external memory unit, an analog-digital converter unit, characterized in that, in order to improve the accuracy and performance of the calibration, a timer unit, a piecewise voltage shaping unit, are introduced into it, block of scale amplifiers, switch block, clock generator and interface, I connect