JPS59842B2 - Fritsuka Yokusei Souchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flicker suppressing device, and in particular, detects load voltage fluctuations, quickly adjusts the amount of reactive power of a reactive power supply device connected in parallel to the load, and suppresses fluctuations in the reactive power of the load. The present invention relates to a flicker suppression device that compensates for.

FIG. 1 shows an example of a conventional flicker suppression device.

FIG. 1 shows only one phase of the three-phase circuit. In FIG. 1, the flicker suppression device includes an AC power supply 1, a power supply impedance 2, a load 3, a reactive power supply device 4, a detection power supply section 5, a differential amplifier 6, a voltage setting terminal 7, a delay circuit 8, and a limiter 9. , automatic pulse phase shifter 10, pulse amplifier 1
Consists of 1. AC power source 1 is supplied to load 3 via current side impedance 2 .

The load 3 is a device that generates flicker, such as an arc furnace.
The reactive power supply device 4 is connected in parallel with the load 3.

! - The reactive power supply device 4 includes a compensation capacitor 41, thyristors 42, 43, and a compensation reactor 44. The detection power supply unit 5 includes a transformer 51, a resistor 52, a capacitor 53,
It consists of a three-phase full-wave rectifier 54.

The transformer 51 includes a primary winding 51a and a secondary winding 51b, and an intermediate tab 57 is provided in the middle of the secondary winding 51b. The transformer 51 is a transformer for detecting variations in load voltage. A resistor 5 is connected to the terminal 55 of the secondary winding 51b.
2 is connected.

Furthermore, a capacitor 53 is inserted between the other end of the resistor 52 and the terminal 56 of the secondary winding 51b. Here, if the resistance value of the resistor 52 is R and the value of the capacitor 53 is C, then 2πF
It is determined to satisfy CR=Vd (where f is the frequency of the power supply).

Further, the effective values of the induced voltages between the terminals 56 and 57 of the secondary winding 51b and between the terminals 55 and 57 are equal, and the phases are shifted from each other by 2π/3. The respective voltages from terminals 56, 57 and terminal 55 via resistor 52 are input to three-phase full-wave rectifier 54. terminal 5
8 is a terminal to which a rectified DC voltage is output. The differential amplifier 6 has one input terminal applied with the output voltage from the detection power supply section 5, and the other input terminal applied with a load voltage setting value E that determines the load voltage to be adjusted from the voltage setting terminal 7. The difference between each input signal is amplified and output.

The delay circuit 8 has a period π/3 included in the rectified output of the terminal 58.
ripples are removed.

The limiter 9 receives the output signal of the delay circuit 8 and is used to suppress firing pulses to the thyristors 42 and 43 within a predetermined control range.

Automatic pulse phase shifter 10 outputs pulses with a phase corresponding to the output signal of limiter 9.

The pulse amplifier 11 amplifies the pulse from the automatic pulse phase shifter 10 and applies a firing pulse to each gate of the thyristors 42 and 43.

The operation of the flicker suppressing device with the above configuration will be explained next.

Due to load fluctuations in the load 3, the load voltage VL exhibits temporal changes as shown in FIG.

In FIG. 2, when the load voltage starts to drop near A in the diagram, the detected voltage at the terminal 58 where the load voltage is constantly detected starts to drop. The difference between this detected voltage and the load voltage set value E is amplified by a differential amplifier 6 and a delay circuit 8, and after ripples are removed, the difference is passed through a limiter 9 and an automatic pulse phase shifter 1.
It is input to 0. The automatic pulse phase shifter 11 delays the phase of the output pulse by a value proportional to the magnitude of the signal. As a result, as shown in FIG. 3, the current flowing through the compensation reactor 44, which had flowed from time t1 in the figure before the voltage drop, begins to flow from time T2, and the current in the compensation reactor 44 decreases. On the other hand, a substantially constant lead current flows through the compensation capacitor 41. Therefore, the reactive power supply device 4 acts as a leading load and increases the load voltage.
A drop in load voltage can be suppressed. Similarly, when the load voltage starts to rise as shown in B in FIG. 2, the operation is reversed to the above operation, and the rise in the load voltage can be suppressed. Normally, the gain of the differential amplifier 6 is sufficiently large, so that the voltage at the terminal 58 (average value) settles down to almost equal to the load voltage setting value E in a steady state, so that Load voltage can be kept constant. The control range of the ignition pulses of the thyristors 42 and 43 is within the range shown in FIG. 3, and the limiter 9 is designed to prevent the ignition pulses from going outside this range. Although the conventional flicker device operates as described above, it has the following drawbacks.

A power system generally has many loads branched out and connected, and a relatively large capacity load among these is 0.
If it fluctuates or starts and stops at a cycle of about 0.01 seconds or more,
The drawback was that it was not possible to suppress load fluctuations in arc furnaces, which were targeted for flicker suppression.

This point will be further explained. FIG. 4 shows the static characteristics between the reactive component of the load current and the load voltage.
Assuming that the influence of the branched load can be ignored, the load curve a will become as the lagging reactive component of the load current increases, and the same amount of leading reactive component will be supplied, so the load curve will become as shown in b. Become flat. However, when the power supply voltage drops by ΔV due to the influence of the branched load,
If there is no flicker suppressor, the load curve is 4th.
It will look like illustration c in the figure. Furthermore, even when the flicker suppression device is connected, the reactive power supply device 4
Since it has only the capacity to increase the voltage of c, the load curve becomes as shown in d of Fig. 4, and the reactive component of the load current is . If the amount exceeds this amount, compensation will not be possible. An object of the present invention is to eliminate the above-mentioned conventional drawbacks, and to provide a flicker suppressing device that is not affected by variations in branched loads.

The present invention eliminates the influence of branched loads by removing voltage fluctuation components with a period of about 0.01 to 0.1 seconds or more, which are not felt as flicker, using a wave filter. .

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 5 is a circuit diagram showing an embodiment of the present invention. Further, FIG. 6 shows a flicker visibility curve, and the present invention utilizes the characteristics of this flicker visibility curve. As shown in FIG. 6, it can be seen that voltage fluctuations around a frequency of 10 Hz are most perceptible to humans. Also, 0.1H
It can be seen that when the temperature reaches z, it decreases to about 8% of 10z, and is hardly felt. The present invention is such that a low frequency door filter 12 and a phase inverter 13 are added to the conventional example shown in FIG.

In FIG. 5, the same components as those in the circuit diagram of the conventional device shown in FIG. 1 are given the same numbers. The low frequency wave generator 12 and the phase inverter 13 are connected in cascade and inserted between the terminal 58 and the voltage setting terminal 7 of the conventional example shown in FIG. The cutoff frequency of the low-frequency door transducer 12 is set to 0.0.
If designed to have a tolerance of 1 to 0.1 Hz, only frequency components of 0.01 to 0.1 Hz (that is, components outside the frequency band defined as flicker) will be passed. This low frequency filter 12
The output signal is inverted by the next stage phase inverter 13 and applied to the input terminal 14 of the differential amplifier 6 as a load voltage setting value that determines the load voltage to be adjusted. The differential amplifier 6 outputs the difference between the detection signal of the detection power supply unit 5 applied to the input terminal 15 and the output signal of the phase inverter 13 . Since the influence of the frequency component of 0.01 to 0.1 Hz has been removed from this output signal, only the flicker component (that is, the component defined as the flicker frequency band) is extracted. Therefore 0.
Since frequencies of 1 to 0.01 Hz never enter the limiter 9, there is no possibility that flicker suppression will become impossible. Below, the operation of each component from the delay circuit 8 to the pulse amplifier 11 will be described in the first section.
Since it is the same as the conventional example shown in the figure, the explanation will be omitted. FIG. 7 is a circuit diagram showing another embodiment of the present invention.

In this embodiment, an amplifier 17 is used in place of the differential amplifier 6 of the embodiment shown in FIG. It is something.
The rest of the structure is the same as the embodiment shown in FIG. In FIG. 7, the detection signal from the detection power supply unit 5 is input to a high frequency door filter 16.

Then, the output signal that has been output is input to the next stage amplifier 17, where it is amplified. This amplified output signal is input to the delay circuit 8. Hereinafter, the operation of each part up to the pulse amplifier 11 is the same as that of the conventional example and the embodiment shown in FIG. 5, and therefore the explanation thereof will be omitted. The cutoff frequency of the high-frequency wave generator 16 is selected to be approximately 0.01 to 0.1 Hz.

As a result, 0.01 to 0.1 which is easy to feel as frizz
Voltage fluctuations at a frequency of Hz or higher are input to the amplifier 17 as a signal, but gentle voltage fluctuations at frequencies lower than that are blocked by the high-frequency wave filter 16 and are not input to the amplifier 17. Therefore, it is not affected by gradual power fluctuations that do not cause frizz. In this embodiment, the amplifier 17 is simply an amplifier because the signal at one input terminal of the differential amplifier may always be zero, and its essential operation remains unchanged. As is clear from the above, according to the present invention, it is possible to operate the flicker suppression device without being affected by voltage fluctuations in a frequency range that is not felt as flicker. can be prevented.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a conventional flicker suppression device, Fig. 2 is a diagram showing temporal changes in the load voltage of the device, and Fig. 3 is a diagram showing the compensation reactor current during operation of the device shown in Fig. 1. 4 is a diagram showing static characteristics between load current and load voltage, FIG. 5 is a circuit diagram showing an embodiment of the present invention, and FIG. 6 is a diagram showing diopter sensitivity characteristics of the eye. FIG. 7 is a circuit diagram showing another embodiment of the present invention. Explanation of symbols, 6...Differential amplifier, 12...
・・Low frequency converter, 13・・・Phase inverter, 16・
...High-frequency door transducer, 17...Amplifier.

Claims (1)

[Claims] 1. A load that is connected to a power source and generates flicker according to its own load state, and a series circuit of at least two thyristors and a reactor connected in parallel to the load, and a control angle of the thyristor. A reactive power supply device that adjusts the amount of reactive power of the load by changing the voltage, thereby suppressing fluctuations in the load voltage; Components other than the specified frequency band are removed, only the components of the detection signal having the frequency band specified as the flicker are extracted, and the detected signal obtained by the extraction is defined as the firing pulse of the thyristor. A flicker suppressing device comprising: ignition means for igniting the thyristor with a pulse. 2. In the flicker suppression device according to claim 1, the ignition means extracts components other than those defined as the flicker from the load voltage detection signal using a low-pass filter; The detected signal is applied to one input terminal of the differential amplifier as the set value of the load voltage to be adjusted, and the detection signal of the voltage of the load is applied to the other input terminal of the differential amplifier. A flicker suppression device configured to fire a thyristor of the reactive power supply device using an output signal of the differential amplifier. 3. In the flicker suppressing device according to claim 1, the ignition means converts the voltage detection signal of the load into a high-pass filter by filtering only the detection signal component having a frequency band defined as the flicker. A flicker suppression device configured to allow a filter to pass through the filter, and use the output signal of the filter to fire a thyristor of the reactive power supply device.