JPH0472578A - Method and circuit for measuring phase difference - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a phase difference measuring method and circuit used in a system connecting a plurality of power systems.

(Prior art) In a system that uses multiple power systems, when a fault occurs in the distribution line of one power system, power is supplied from another power system to prevent problems such as power outages. Furthermore, even if a failure occurs, the system is designed to be restored within the 9th term.

When switching power systems like this, it is necessary to match the phase of each power system, so the phase difference of each power system is measured by a phase difference measurement circuit installed in the box of the ten utility poles. When the phase difference is within the specified value, the power grid is switched after adjusting the phase difference to zero, and when the phase difference is greater than the specified value,
Switch the power system to medium (-).

FIG. 2 is a block diagram showing an example of a phase difference measuring circuit for measuring the phase difference of such a power system.

The phase difference measurement circuit shown in this figure includes a first input circuit 101 that takes in the voltage signal of one power system, a second input circuit 102 that takes in the voltage signal of the other power system, and these containers 1, It is equipped with a phase comparison circuit +03 that detects the phase difference between each power system based on the signal output from the second input circuit 1o1102, and it takes in the voltage signal of each power system and measures the phase difference between them. Output the results.

The first and second input circuits 101 and 102 each include a low-pass filter that filters the input voltage signal (phase θ1, θ2) and a buffer amplifier that amplifies the output signal of this low-pass filter. 8. The phase comparison circuit +03 receives the voltage signal of the first and second input circuits, filters it, amplifies it, and supplies it to the phase comparison circuit +03.
The phase difference between the signals (phases θ1, θ2) supplied from +02 is measured and the measurement result “θ1θ2” is output.

However, in such a phase difference measurement circuit,
Due to characteristic errors of the first and second input circuits 101 and 102, errors due to temperature fluctuations, etc., the first and second input circuits lot,
There are errors Δθ1 and Δθ2 for every +02.

Therefore, the phases of the signals output from the first and second input circuits lot and 102 are "θ1+Δθ1" and "θ2+
Δθ2”, and the phase comparator circuit outputs “(θ1−02)+(ΔθI−02)” as a measurement result.

Therefore, in order to solve this problem, the first and second
It is conceivable to carefully select the components used in the input circuit lo1.102, but if this is done, the problem arises that the design becomes difficult and the cost increases.

(Objective of the Invention) The present invention was made in order to eliminate the above-mentioned conventional drawbacks, and it is possible to simplify the design, reduce the cost, and reduce the characteristic error and temperature of the parts used. It is an object of the present invention to provide a phase difference measurement method and a circuit thereof that can eliminate measurement errors caused by characteristic changes caused by.

(Summary of the Invention) In order to solve the problem described in item L, in the signal phase difference measuring method and its circuit according to the present invention, in the first measurement mode, the Ih signal of the first power system is supplied to the first input circuit, and , supplying (-series) of the second power system to the second input circuit;
Then, the phase difference between the signals output from the first and second input circuits is measured, and this measurement result is used as the first measurement result.After that, during the second measurement period, the signal of the first power system is used as the first measurement result. 2 input circuit, and also supplies the signal from the second power system to the first
Measure the phase difference of each signal supplied to the input circuit and output from these first and second input circuits, take this measurement result as a second measurement result, and based on the difference between these first and second measurement results. The method is characterized in that the phase difference between the first and second power systems is determined.

(Examples) Hereinafter, the present invention will be described in detail based on illustrated examples.

FIG. 1 is a block diagram showing one embodiment of the present invention.

The phase difference meter circuit shown in this figure includes a switching circuit 1 that takes in the voltage signals of the first and second power systems, a first input circuit 2 that takes in the single voltage signal output from the switching circuit 1, and a switching circuit 1 that takes in the voltage signals of the first and second power systems. A second input circuit 3 that takes in the other voltage signal output from circuit l, and these first and second input circuits 2.3
and a phase comparison circuit 4 for detecting a phase difference between the first and second power systems based on a signal output from the first and second power systems.
The voltage signal of the second power system is taken in, the phase difference thereof is measured, and the measurement result is output.

The switching circuit 1 includes two changeover switches 5.6,
When the common terminal 5C16c of each changeover switch 5.6 and the - terminals 5a, 6b are connected, the changeover switch 5 controls the voltage signal (phase θl) of the first power system.
) is taken in and supplied to the first input circuit 2, and the voltage signal (phase θ2) of the second power system is taken in by the changeover switch 6 and supplied to the second input circuit 3. Common terminal 5c of switch 5.6.

6c and the other terminals 5b and 6a are connected, the changeover switch 5 switches the voltage signal (
It takes in the phase θ2) and supplies it to the first input circuit 2, and also takes in the voltage signal (phase θ1) of the first power system by the changeover switch 6 and supplies it to the second input circuit 3.

The first and second input circuits 2.3 each include a low-pass filter that filters the input voltage signal, and a buffer amplifier that amplifies the signal filtered by the low-pass filter. It takes in a voltage signal, filters it, amplifies it, and supplies it to the phase comparator circuit 4.

The phase comparison circuit 4 removes phase errors Δθl and Δθ2 generated by the first and second input circuits 2 and 3 based on the voltage signals supplied from the first and second input circuits 2.3. The phase difference between the first and second power systems is measured and the measurement result "θl-02-" is output.

Next, the operation of this embodiment will be explained with reference to FIG.

First, the common terminals 5c, 6c of each changeover switch 5.6 and one terminal 5a, 6b are connected, and the first input circuit 2 outputs a voltage signal on the first power system side, and the second
When the input circuit 3 outputs the voltage signal on the second power system side, the phase comparator circuit 4 outputs the voltage signal on the first and second power system side from the first and second input circuits 2.3. The measured value A is obtained by performing the calculation shown in the following equation based on the following equation, that is, the calculation of subtracting the output of the second input circuit 3 from the output of the first input circuit 2.

＾・(θ1◆△θ1)−(02◆Δθ2)・(θ1−0
2)◆(801-△θ2) ... (+) However, θI: Phase of the voltage signal of the first power system output from the first input circuit 2 θ2: Output from the second input circuit 3 Phase Δθ1 of the voltage signal of the second power system, Phase error Δθ2 of the first input circuit 2: Phase error of the second input circuit 3. After this, each changeover switch 5.6 is switched to connect the common terminals 5c, 6c and the other terminals 5b and 6a are connected, the first input circuit 2 outputs a voltage signal on the second power system side, and the second input circuit 3 outputs a voltage signal on the first power system side. Based on the voltage signals of the first and second power systems outputted from the first and second input circuits 2.3, the phase comparator circuit 4 performs the calculation shown in the following equation, that is, calculates the A calculation is performed to subtract the output of the two-input circuit 3 to obtain the measured value B.

B・(θ2◆01)−(01◆△θ2)・(θ2−0
1)◆(Δθl−Δθ2) (2) Then, when this calculation is completed, the phase comparator circuit 4 calculates the total 711I value A obtained by these equations (1) and (2).
, B to calculate the phase difference C by performing the calculation shown in the following equation, and output this as a measurement result.

C・(A-8+/2・θ1-02...(3) In this way, in this embodiment, the first and second input circuits 2
．． Even if there is a phase error in the first and second input circuits 2.3, the phase comparator circuit 4 calculates the phase errors △θl, △ of these first and second input circuits 2.3.
Since θ2 is canceled by 1, it is possible to simplify the circuit design (this also reduces the cost by 1-1).
It is possible to eliminate measurement errors caused by characteristic errors of used parts, characteristic changes due to temperature, etc. while holding the stomach.

(Effects of the Invention) As explained above, according to the present invention, it is possible to simplify the design, reduce the cost, and eliminate measurement errors caused by characteristic errors of used parts and characteristic change records due to temperature. Errors can be eliminated.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a phase difference measuring circuit to which the signal phase difference measuring method according to the present invention is applied, and FIG. 1 is a block diagram showing an example of a conventionally known phase difference measuring circuit. DESCRIPTION OF SYMBOLS 1...Switching circuit, 2...1st input circuit, 3...2nd manpower port jJ path, 4...phase comparison circuit.

Claims (2)

[Claims] (1) When in the first measurement mode, the signal of the first power system is
At the same time, a signal from the second power system is supplied to the second input circuit, and the phase difference between the two signals output from the first and second input circuits is measured, and this measurement result is transferred to the first power system. After that, in the second measurement mode, the signal of the first power system is supplied to the second input circuit, and the signal of the second power system is
A power system signal is supplied to the first input circuit, and the phase difference between the two signals output from the first and second input circuits is measured, and this measurement result is used as the second measurement result. A phase difference measuring method characterized by determining a phase difference between a first power system and a second power system based on a difference between two measurement results. (2) When in the first measurement mode, capture the signal from the first power system and output it from the first output terminal,
It takes in the signal of the second power system and outputs it from the second output terminal, and when in the second measurement mode, it takes in the signal of the first power system and outputs it from the second output terminal, and also takes in the signal of the first power system and outputs it from the second output terminal. a switching circuit that takes in the signal and outputs it from a first output terminal; a first input circuit that processes and outputs the signal output from the first output terminal of this switching circuit; and a second output of the switching circuit. determining a phase difference between a second input circuit that processes and outputs a signal output from a terminal, and signals output from the first and second input circuits in a first measurement mode to obtain a first measurement result; In the second measurement mode, the phase difference between the signals output from the first and second input circuits is determined to obtain a second measurement result, and then the first and second input circuits are
A phase difference measurement circuit comprising: a phase comparison circuit that calculates a difference between measurement results and outputs this difference as a phase difference value.