SU842619A2 - Device for measuring electrical network parameters - Google Patents

Description

(54) DEVICE FOR MEASUREMENT OF ELECTRIC NETWORK PARAMETERS

The invention relates to information measuring equipment and is intended for use in the power industry as a measuring converter for automated dispatching control systems with digital computers, and can also be used as an autonomous device for measuring and controlling electrical network parameters. According to the main auth. No. 739428, a device for measuring the voltage parameters of an industrial network, comprising drivers, a frequency multiplier, a summing-subtracting node, a code-to-frequency converter, a reversible counter, a coincidence element, a unit for extracting the difference of periods, a unit for generating operating hours, frequencies, a frequency divider. In this device, the drivers are connected to the input buses of the device, and the output of the first driver is connected to a frequency multiplier connected to the summation reading node, another input connected to a code-to-frequency converter, whose input is connected to a reversible counter connected to the matching element. one input of which is connected to a Period Difference Isolation Unit, and the other is connected to a working frequency shaping unit connected to a frequency divider, which in turn is connected to a loop reading reader and a period difference isolating unit. Building this device on a closed structure can significantly improve the measurement accuracy, since the error is determined only by the accuracy characteristics of the nodes of the feedback circuit I, However, the functionality of this device is limited, which requires several autonomous devices for measuring various parameters of the variable tension The purpose of the invention is to expand the functionality, which consists in measuring the difference between two frequencies and phase shift. This goal is achieved by the fact that in a device containing a frequency multiplier, a summing-subtracting node, a code-to-frequency converter, a reversible counter, a circuit

coincidence, the scheme of the period difference between the circuits, the working frequency shaping scheme, the frequency divider and two fopes: the driver,. connected to the input buses of the device, the output of the first of which is connected, with a frequency multiplier connected to the summing-subtracting node, the other input of which is connected to a code-to-frequency converter, the inputs of which are connected to a reversible counter connected to the coincidence circuit by one input connected to the allocation circuit of the period difference, the other to the operating frequency driver circuit connected to the frequency divider, which is connected to the summation-subtractive node and the period difference extraction circuit, entered storage, two additional matching elements, a pulse counter, and an RS trigger, the first input of the storage register connected to the output of the first additional matching element, and its second output connected to the output of the pulse counter, the first input of which is connected to the output of the second additional matching element first input which is connected to the output of the RS-flip-flop, and the second input is connected to the first input of the splitter, the second input of which is connected to the second input of the impulse counter and the first input of the R5-flip-flop, and the third stroke extracting difference block periods and the discharge outlet are connected to the down counter vhoh1; s first additional coincidence of the element, and a second input connected to the output RStriggera first shaper.

Figure 1 shows a diagram of the proposed device; in FIG. 2, timing diagrams.

The device contains E Egister 1 Hrneni, three elements 2-4 are the same: and, counter 5 pulses, RS-flip-flop b, frequency divider 7, block 8 select the difference of periods, reversible counter 9, drivers 10 and 11 pulses, multiplier 12 frequencies, Converter 13 code to frequency, block 14 of the formation of the working cha, one hundred, you and summing-subtracting node 15.

The device works as follows

In the mode of determining the phase shift, the input frequencies F and Fj are frequency-pulse sequences (Lig. 2), the pulses are formed at the moment the AC voltage passes through the zero value.

The period difference allocating unit 8 generates two equal in size but half-period shifted pulse sequences (Fig 2b, c). Regarding one of

they are used to determine the phase shift (a f,) using the RS flip-flop 6 During the time interval equal to the phase shift qh, cha, the input of the counter 5 pulses receives a pulse frequency sequence

kF-, (k - multiplied coefficient, n). The resulting code is rewritten into the storage register 1 by frequency pulses F / 2 at the zero state of the reversible counter 9 (i), i.e. when the frequencies F ,, and Fj are equal. Only in this case the code in the counter of 5 pulses is proportional to the phase shift.

, g LU, KF-, y.

Mdh dh

 CD, as follows from the expression by the boron coefficient of the force of mocha to set the weight of -Lpadu) of it, and the indicated code. Taic when the device measures the phase shift with an accuracy of 0, 1.

The proposed device allows to measure two parameters with high accuracy (frequency difference and shift P) simultaneously of alternating current voltages with minor hardware costs. The absolute error in measuring the frequency difference is 0.01 Hz, the absolute error in measuring phase shift

Claims (1)

1. Author's sweater; USSR № 739428, cl. G 01 R 23/10, 1978. V L / FIG. 2