SU1002975A1 - Ac power electronic meter - Google Patents

Description

The invention relates to a measurement technique and can be used to build active and reactive power meters in automatic power system devices.

A static active and reactive power measuring transducer is known, comprising measuring current and voltage transformers, a scanning voltage generator, potentiometers, keys, a comparison device, and memory blocks 1}.

The disadvantages of this device are its complexity, and as a result, reliability is low.

The closest to the invention in its technical essence is a device for measuring the active and reactive power of alternating current, which contains current and voltage transformers, a switch, a multiplier and a filter 2.

A disadvantage of this device is the impossibility of simultaneously measuring the active and reactive powers and, as a result, the low speed of the device.

The aim of the invention is to improve the speed of the device by

simultaneous measurement of active and reactive power.

The goal is achieved by the fact that an electronic AC power meter containing the first smoothing filter, the first key and the multiplication unit, to the first input of which a current transformer is connected, and to the second input

10 through the second key - a voltage transformer, a phase-shifting chain, a third and fourth keys, a second smoothing filter, and a signal and

15 the control inputs of the second key are combined, the output of the voltage transformer is connected via a phase-shifting chain connected in series and the first key to the second input of the multiplication unit whose output is connected to the signal inputs of the third and fourth keys, the outputs of the latter are connected to the output buses through the first and second smoothing

25 filters, and the control inputs with the control input of the first key and the output of the voltage transformer.

The drawing shows the block diagram of the electronic meter

30 AC power.

The device contains a voltage transformer 1, the output of which is connected to the input of the phase-shifting chain 2, the combined control and signal inputs of the key 3, the control input of the key 4, the signal input of which is connected to the output of the phase-shifting pin 2, and the output connected to the first input of the multiplication unit 5 The output of which is connected to the signal inputs of keys 6 and 7, the outputs of which are connected to the output buses through smoothing filters 8 and 9, respectively, and the control inputs to the output of voltage transformer 1, the output of transformer 10 current is connected to the second, the input of the multiplication unit 5, and the power supply unit 11.

The device works as follows.

The input voltage is fed to the voltage transformer 1, from the output of which this signal goes to the inputs of keys 3, 4, b and 7 and to the input of the phase-shifting chain 2. In one half-period of the input voltage, let's say the first, keys 4 and 6 are opened, in the second half period, the keys 3 and 7 are open. In the first half period from the output of the phase-shifting chain 2, the input voltage voltage shifted by 90 ° through the public key 4 is fed to the input of multiplication unit 5, in which it multiplies with the current signal of the monitored circuit. In the second half-period, the signal voltage is fed to the input of multiplication unit 5, through the public key 3, and also multiplied with the input current. Thus, the output of the multiplier separates the signal that contains information about the average active and reactive powers of the controlled circuit. The separation of these signals is performed by synchronously operating keys 6 and 7. From the signals coming from the outputs of switches b and 7, the smoothing filters 8 and 9 separate the signals of the average reactive and active powers of the controlled circuit, respectively. An electronic AC power meter uses a multiplier with a pulse width amplitude modulator. At its output, the signals are modulated by the amplitude of the voltages from the outputs of the phase-shifting chain 2 and the transformer 1, and by the duration - by the current from the output of the current transformer 10. The keys 6 and 7 and the smoothing filters 8 and 9 isolate the components of the average reactive and active powers, respectively.

Introduction to Electronic Meter

AC power of two | keys, a smoothing filter and a phase-shifting chain allows simultaneous measurement of active and reactive power and

thereby increasing the speed of the device at least twice.

Claims (1)

Invention Formula An electronic AC power meter containing the first smoothing filter, the first key and a multiplication unit, to the first input of which a current transformer is connected, and to the second input through a second key - a voltage transformer, which differs so that in order to increase its speed, the third and fourth keys are additionally introduced, the phase-shifting chain and the second smoothing filter, the signal and control inputs of the second key are combined, the output of the voltage transformer is connected through the phase-shifting chain connected in series and the first key to the second input of the multiplication unit whose output connected to the signal inputs of the third and fourth keys, the outputs of the latter are connected to the output buses through the first and second smoothing filters, and the control inputs are connected to the control input of the first key and the output of the voltage transformer. Sources of information taken into account in the examination of the USSR Copyright Certificate № 759970, .cl. G 01 R 21/00, 28.06.78. . ingegneria eEektronica nucfeare e strument. 1966, V.4, 11, p. 3-7 (prototype).