SU1451611A1 - Threshold sensor of active current - Google Patents

Abstract

The invention can be used when comparing two active currents of the same network phase, for example, in load sharing devices between synchronous generators. The purpose of the invention — improving accuracy and noise immunity for non-sinusoidal load currents — is achieved by additionally introduced voltage sensor 3, triggers 7 and 8, integrators II and 12, bit switches 9 and 10, subtractor 13 and Schmidt trigger 14. The signaling of zero voltage transfer from sensor 3 through pulse generator 6 sets the triggers 7 and 8, as well as the integrators 11 and 12 to the zero state. The pulses from current sensors 1 and 2, formed by shaper 4 and 5, respectively, trigger triggers 7 and 8, and integrators 11 and 12 at their output generate a signal proportional to the pulse duration from the trigger output 7 and 8. At the output of the subtractor 13, voltage proportional to the difference of the comparative currents, taking into account the phase. The trigger 14 sets the threshold for comparison of the measured currents. 1 il. to (L S

Description

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The invention relates to electrical engineering and can be used in devices where a comparison of two active currents of the same phase is required, for example, in load sharing devices between synchronous generators.

The purpose of the invention is to improve the measurement accuracy and noise immunity of the device with non-sinusoidal load currents.

The drawing shows a functional diagram of the device

The threshold active current sensor contains sensors 1 and 2 of full current voltage sensor 3, the outputs of sensors 1 and 2 of full current and voltage sensor 3 are connected to the inputs of the

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Claims (1)

The 4.5 and 6 pulses of the corresponding-2o at the output of the subtractor 13 are less than the trigger threshold of the Schmidt trigger 14, it does not work, indicating that the power of the controlled circuit is active within the specified limits. Formula A threshold active current sensor containing two total current sensors, the outputs of which are connected to the inputs of the first and second pulse shapers, respectively, is the third pulse shaper, which is different in order to improve measurement accuracy and noise immunity of the sensor when non-sinusoidal currents on; loads, a voltage sensor, two triggers, two integrators, two bit keys, a reader and a Schmidt trigger are entered into it, and the output of the first driver of the pulses is connected to the S input of the first trigger, output It is connected to the input of the first integrator, the output of which is connected to the first input of the subtractor, the output of which is connected to the input of the P1midt trigger, two outputs of which are sensor outputs, the second input of the subtractor is connected to the output of the second integrator, the input of which is connected to the output of the second trigger, S- the input of which is connected to the output of the second pulse generator, the R-inputs of both triggers are connected to the control inputs of both bit switches and the output of the third pulse generator, the input of which is connected to the output of the sensor voltage outputs bit keys are connected with the control inputs of the two integrators, respectively. but, K the inputs of the trigger 7 and 8 are connected to the control of the gas inputs of bit 9 and 10 and the output of the driver 6 pulses, the outputs of the bit switches 9 and 10 are connected to the control inputs of the integrator 11 and 12, respectively, the input of the integrator 11 is connected to the output of the trigger 8, the S input of which is connected to the output of the pulse former 4, the input of the integrator 12 is connected to the output of the trigger 7, the S input of which is connected to the output of the pulse former 5, the output of the integrator 12 is connected to the first input of the reader 13, the second input is connected to the output and The integrator 1I, the output of the subtractor 13 is connected to the input of the Schmidt trigger 14, the two outputs of which are the outputs of the device. A full current sensor 1 measures the current in circuit 15 of the first generator (load), and a full current sensor 2 measures the current in circuit 16 of the same second phase generator (load). Voltage sensor 3 measures the voltage of the same phase relative to the neutral wire of a three-phase network 17, The device works in the following way. The shapers of 4.5 and 6 pulses produce short pulses at times of current or voltage passing through zero, respectively. The phase shift between the voltage and the corresponding current (in chains of 15 and 16) is proportional to the time interval between the moments of time of the transition of the phase voltage and the current. 35 40 45 50 55 through zero, while for greater active power this time interval is smaller and vice versa. The impulses, phase transition voltage across zero, arriving at the R-inputs of the flip-flops 7 and 8, set them to the zero state and simultaneously integrate the integrators M and 12 through the bit switches 9 and 10, The pulses from the formers 4 and 5 trigger the triggers 7 and 8, and the integrators 11 and 12 accumulate a charge proportional to the pulse duration at the output of the triggers 7 and 8, respectively. The voltage from the outputs of the integrators 1 and 12 is fed to the inputs of the subtractor 13, If the difference of the voltages