JPH04217811A - Higher harmonic detecting alarm device - Google Patents

Abstract

PURPOSE:To provide a detecting alarm device by which an alarm can be generated by adequately detecting a component of higher harmonics. CONSTITUTION:A signal voltage generating circuit 2 for outputting signal voltage of level corresponding to the level of a higher harmonic component in a synthetic wave, a reference voltage generating circuit 3 for increasing or decreasing a reference voltage with time when the level of the signal voltage exceeds a preset value, a compared voltage generating circuit 4 for decreasing or increasing a compared voltage in accordance with the level of the signal voltage exceeding a preset value, a comparator circuit 5 for outputting an alarm signal when levels of the above-mentioned reference voltage and compared voltage are reversed and an alarm means 6 for generating an alarm based on an output of this comparator circuit 5 are provided. Since the substantial preset value is automatically changed in accordance with the level of the higher harmonic component not to generate an alarm immediately upon exceeding an alarm point and to generate an alarm early upon exceeding the alarm point significantly, a higher harmonic component alarm device excellent in practicability is obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alarm device that detects harmonic currents and harmonic voltages in power receiving and distribution lines, etc., and issues an alarm when the content rate or voltage distortion rate of harmonic components exceeds a set value.

0002

[Background Art] When currents and voltages in power receiving and distribution lines contain many harmonic components, various problems occur such as abnormal heating due to overloading of phase advance capacitors, abnormal vibrations of rotating machines, and malfunctions of electronic equipment. . Therefore, it is necessary to monitor the harmonic components of the power supply waveform so that they do not exceed a certain level, and to take appropriate measures if they exceed a certain level. The present applicants have previously proposed a harmonic measuring meter that is easy to handle for this purpose (see, for example, Japanese Utility Model Application Publication No. 46764/1983). Using this, it is possible to extract harmonic components from a composite wave containing harmonics and monitor their levels, and it is also possible to automatically issue an alarm when a certain level is exceeded.

0003

[Problem to be Solved by the Invention] The above-mentioned alarm device compares the level of the harmonic component to be monitored with a set voltage (reference voltage), and issues an alarm when the harmonic component exceeds the reference voltage. It is common to do something like this. However, in the case of such a device, an alarm is immediately issued if the harmonic component exceeds a set value even by a small amount. For this reason, if the set value is too low, the frequency of alarms will increase, and conversely, if the set value is too high, the necessary alarms may not be issued, making it difficult to judge where to set the alarm point. This was difficult and one of the practical problems. The present invention has focused on such problems, and aims to provide a detection and alarm device that can issue an alarm appropriately by changing the actual setting value depending on the level of the harmonic component. It has been done.

0004

[Means for Solving the Problems] In order to achieve the above object, the harmonic detection and alarm device of the present invention extracts harmonic components from a composite wave containing harmonics, shapes the waveform, and adjusts the magnitude of the components. A signal voltage generation circuit that outputs a signal voltage at a level corresponding to Comparing the reference voltage and the compared voltage with a compared voltage generating circuit that outputs a voltage to be compared that is lowered or increased as the level of the signal voltage is higher, in the opposite direction to the reference voltage, A comparison circuit that outputs an alarm signal when the levels of the voltage to be compared and the reference voltage are reversed, and an alarm means that issues an alarm based on the alarm signal of the comparison circuit are provided.

[0005]

[Function] Even if the signal voltage corresponding to the magnitude of the harmonic component exceeds the set value, if the level is low, the compared voltage will increase, and it will take time until the level of this voltage and the reference voltage are reversed. As the time increases, the output of the alarm signal becomes slower. Therefore, if the signal voltage returns below the set value by then, the alarm signal will not be output. On the other hand, when the level of the signal voltage is high, the voltage to be compared becomes low, and the time until the level of the reference voltage is reversed is shortened, so that the alarm signal is outputted quickly. Therefore, after the signal voltage exceeds the set value, the time during which it can return below the set value before an alarm signal is output becomes shorter as the signal level increases, and when the signal voltage exceeds the set value, the alarm signal is immediately output. become.

[0006] In other words, the actual set value automatically changes depending on the extent to which the signal voltage exceeds the set value, and it is not possible for an alarm to be issued immediately if the signal voltage slightly exceeds the set value. Moreover, if the signal voltage greatly exceeds the set value, an alarm is issued immediately, so an appropriate alarm is issued depending on the magnitude of the harmonic component, improving the practicality of the detection and alarm device. .

[0007]

[Embodiment] Next, an embodiment shown in the drawings will be explained. FIG. 1 is a block diagram of the entire device, FIG. 2 is a circuit diagram of an alarm generation section, and FIG. 3 is an explanatory diagram of its operation. In FIG. 1, 1 is a composite wave input terminal, 2 is a signal voltage generation circuit, 3 is a reference voltage generation circuit, 4 is a compared voltage generation circuit, 5 is a comparison circuit, and 6 is an alarm means.

The signal voltage generation circuit 2 is a fundamental wave extraction circuit 2.
1. It is equipped with a subtraction circuit 22, a waveform shaping circuit 23, etc., and the composite wave input terminal 1 is connected to the power receiving and distribution line to be monitored, and the fundamental wave is first extracted from the composite wave containing harmonics that will be input. A circuit 21 extracts the fundamental wave. Then, the fundamental wave and the composite wave are subjected to subtraction processing in the subtraction circuit 22 to extract only the harmonic components included in the composite wave, and this is waveform-shaped in the waveform shaping circuit 23 according to the magnitude of the harmonic components. It is configured to obtain a signal voltage V0 of a certain level. Note that this signal voltage generation circuit 2 can adopt, for example, a circuit configuration as disclosed in the above-mentioned publication, and the harmonic components to be extracted are composite harmonic components including all harmonics,
It is desirable to be able to arbitrarily select any single harmonic component of a specific frequency.

Next, the alarm generating section will be explained with reference to FIGS. 2 and 3. In FIG. 2, reference numeral 7 denotes an operation level setting circuit composed of a variable resistor R0 and a series circuit of resistors R1 to R7. The reference voltage generation circuit 3 includes a comparator 31 and a resistor 32.
, an integrating circuit consisting of a capacitor 33 and a diode D1. The comparator 31 is supplied with the terminal voltage of the variable resistor R0 of the operation level setting circuit 7 as a reference voltage, and is also supplied with the signal voltage V0 output from the signal voltage generation circuit 2, and integrates the output voltage to obtain a signal. The terminal voltage V1 of the capacitor 33 is used as the reference voltage of the comparator circuit 5.

The compared voltage generating circuit 4 includes comparators 41 to 46.
, resistors 47 and 48, and resistors R11 to R16. Each comparator 41 to 46 is provided with the terminal voltage of the resistor R1 to R6 of the operation level setting circuit 7 as a reference voltage, and is also provided with the signal voltage V0 output from the signal voltage generation circuit 2, and its output side is each resistor R11~
Connected to the connection point of resistors 47 and 48 via R16,
The voltage V2 at this connection point is used as the voltage to be compared in the comparator circuit 5. The alarm means 6 is the comparison circuit 5
It is activated by an alarm signal V3 outputted from the controller, and is configured to emit an alarm sound using a buzzer, for example, or display an appropriate alarm display.

This embodiment has the above-mentioned configuration and operates as follows. Signal voltage V0 of signal voltage generation circuit 2
are compared with their respective reference voltages by comparator 31 and comparators 41-46. Operation level setting circuit 7
The variable resistor R0 is used to set the basic alarm point, and when the level of the signal voltage V0 exceeds the terminal voltage of the variable resistor R0, the output of the comparator 31 becomes "H", and the capacitor 33 and the resistor 32 It is charged at a determined time constant, and its terminal voltage V1 gradually increases as shown in FIG.

Here, the level of the terminal voltage V1 is determined by the comparator 4.
1 reference voltage, that is, the terminal voltage of the resistor R1, the outputs of the comparators 41 to 46 all become "H", and the output voltage V2 of the compared voltage generating circuit 4 is a high voltage determined by the resistors 47 and 48. becomes. V20 in FIG. 3 indicates this voltage. Therefore, the voltage V20 and the terminal voltage V
It takes time t0 for the comparator 31 to reach 1, and the output of the comparator circuit 5 becomes "H" after time t0 after the output of the comparator 31 becomes "H", and the alarm signal V3 is output, and the alarm means 6 is activated. Operate.

Further, when the level of the signal voltage V0 is higher than the terminal voltage of the resistor R1 and lower than the terminal voltage of the resistor R2, the output of the comparator 41 becomes "L" and the resistor R11 is connected in parallel with the resistor 48. It becomes a shape. Therefore, the output voltage V2 of the compared voltage generation circuit 4 is V20 as shown in FIG.
It becomes V21, which is slightly lower. Therefore, the time it takes for the terminal voltage V1 to reach this voltage V21 is t, which is slightly shorter than t0.
1, the output of the comparison circuit 5 becomes "H" after time t1, the alarm signal V3 is output, and the alarm means 6 is activated.

[0014] When the level of signal voltage V0 further increases,
Accordingly, the outputs of the comparators 42 to 46 become "L" one after another, and the number of resistors R12 to R16 connected in parallel with the resistor 48 increases, so that the output voltages of the compared voltage generation circuit 4 are V22, V23. ...and gradually decrease. For this reason,
The time during which the alarm signal V3 is output also becomes shorter in sequence from t2, t3, etc., and the alarm signal V3 is output sooner. On the other hand, if the level of signal voltage V0 becomes lower than the terminal voltage of variable resistor R0 before alarm signal V3 is output,
The output of the comparator 31 becomes "L", the terminal voltage V1 of the capacitor 33 does not rise any further, and the alarm signal V3 is not output because it is discharged through the diode D1 and returns to the standby state. As described above, the higher the level of the signal voltage V0, the shorter the time until the alarm signal V3 is output.

Therefore, the actual alarm point automatically changes depending on the extent to which the signal voltage V0 exceeds the terminal voltage of the variable resistor R0. No alarm is issued, and if there is an excessive input, the alarm is issued earlier depending on the amount. Note that the circuit configuration of the embodiment is an example, and it is possible to obtain the reference voltage generation circuit 3 and the compared voltage generation circuit 4 using other circuit configurations. Further, depending on the circuit configuration, the direction of voltage change may be reversed from this embodiment, so that the reference voltage is lowered and the compared voltage is increased.

[0016]

[Effects of the Invention] As is clear from the above-described embodiments, the present invention is such that the actual setting value is automatically changed according to the level of the harmonic component extracted by the signal voltage generation circuit. Therefore, if the harmonic component slightly exceeds the alarm point, an alarm will not be issued immediately; however, if the harmonic component greatly exceeds the alarm point, the alarm will be issued earlier depending on the amount. Therefore, it is easy to set the basic alarm point, and the alarm is issued appropriately depending on the magnitude of the harmonic component, so it is possible to obtain a harmonic component alarm device with excellent practicality. This makes it easier to monitor the harmonic components and take appropriate measures.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an entire apparatus according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of an alarm generating section of the same embodiment.

FIG. 3 is an explanatory diagram of the operation of the same embodiment.

[Explanation of symbols]

2 Signal voltage generation circuit 3 Reference voltage generation circuit 4 Compared voltage generation circuit 5 Comparison circuit 6 Alarm means 7 Operation level setting circuit 31, 41-46 Comparator 32, 47, 48 resistance 33 Capacitor R0 Variable resistance R1~R7, R11~R16 Resistance V0 Signal voltage V3 Alarm signal

Claims (1)

[Claims] Claim 1: A signal voltage generation circuit that extracts harmonic components from a composite wave containing harmonics, shapes the waveform, and outputs a signal voltage at a level corresponding to the magnitude of the component; A reference voltage generation circuit that outputs a reference voltage while increasing or decreasing over time when it exceeds a set value, and a reference voltage generation circuit that outputs a reference voltage that increases or decreases over time depending on the level of the signal voltage that exceeds a set value. A comparison circuit that compares the reference voltage and the voltage to be compared and outputs an alarm signal when the levels of the voltage to be compared and the reference voltage are reversed, and a comparison circuit that outputs an alarm signal using the alarm signal of this comparison circuit. A harmonic detection alarm device comprising: alarm means for emitting an alarm.