JPS5810213A - Control circuit for flicker absorber - Google Patents

Abstract

PURPOSE:To decrease the fluctuation of power supply voltage, by supplying ineffective power in response to a rapid load fluctuation, through the provision of a current transformer detecting a current of a load with large flicker. CONSTITUTION:When a current TC flows to a converter CV, a relation with the secondary voltage V of a transformer PT is calculated and a converted voltage DC1 is outputted. On the other hand, a synchronizing compensator SC1 outputs a compensated voltage DC2 with a current 1C of a load L1 and a forecasting signal B1. A compensated voltage DC2 and the converted voltage DC1 are synthesized to obtain a control signal DC4. A pulse generator receiving the control signal DC4 generates a pulse P with the secondary voltage V of the transformer and a trigger pulse is given to a thyristor SCR of a flicker absorber F to control a control current FC. In this case, when the flicker absorber is employed with a reactor, the trigger angle of the thyristor SCR is controlled and when the absorber is provided with a capacitor, the number of triggered SCRs can be controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control circuit for a 7-resoka absorption device that reduces power supply voltage fluctuations by supplying reactive power in response to rapid load fluctuations.

Conventionally, this type of device has used either a method of detecting the load current or a method of controlling using a prediction signal. The former has the advantage of absorbing voltage fluctuations due to the entire load in the factory, but has the disadvantage of causing a control delay. It had the disadvantage of being unnatural.

The present invention has been devised to satisfy both requirements at the same time, and is particularly designed to control loads that generate large flicker by using a predictive signal, and to control other loads by mainly using the load current. In this way, we tried to take advantage of the strengths of both.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a single line diagram for explaining the present invention in detail. A single-line diagram is a drawing drawn with a single line, omitting the three-phase circuit.

Now, the synchronous compensator EI01 in FIG. E+02. Considering the case where control is performed using only the signals of the secondary current To of the current transformer oT and the secondary voltage V of the transformer FT without using the
As shown in the figure, the converted voltage DO1 is generated with a delay from the secondary current To of the current transformer OT (hereinafter, in the main text and drawings, the secondary current To of the OT is abbreviated as the total current), and even later than that. Since the control current FO flows, it is impossible to prevent the voltage fluctuation △V of the power supply.

Next, only the synchronous compensator 801 in FIG. 2 is used as an input circuit, and the load L1 in FIG. If there is no load other than that, as shown in Figure 3, before the total current TO flows,
Since the prediction signal B1 becomes zero before the prediction signal B1 is generated and the total current TO becomes zero, the control signal DO4 becomes the total current T.

As a result, the delay in the control current po disappears, and the voltage fluctuation ΔV exceeds zero.

Next, let us consider a case where control is performed by making full use of the entirety of FIG. This seems to be a combination of the operations shown in FIGS. 5 and 4, but in reality, the load L1. L2. Since this current is included in the total current TO, if this current is left as it is, it will result in double control, which is not good. Therefore, in the present invention, as shown in FIG. 5, the prediction signal B1 is processed and used as the compensation voltage na2.

That is, the compensation voltage D02. When the components of the load I, 1 included in the total current TO are summed, the waveform is the same as that of the control signal DO4 in FIG. 4. load n5
．． L4. ...When bowing, the action is similar to that shown in Figure 3.

Hereinafter, FIGS. 2 and 5 will be explained in detail. Fifth
The figure shows the load L1. of FIG. This figure shows the operation when current flows only through. When the total current TO flows through the transformer Ov, the relationship with the secondary voltage V of the transformer FT is expressed as the transformer Ov
calculates and outputs the converted voltage DO1.

On the other hand, the synchronous compensator 801 outputs the compensation voltage DO2 based on the current 10 of the load L1 and the prediction signal E1. At this time,
The previous current is memorized and used as the initial value of the current 1C. A three-phase synthesizer 3 converts the converted voltage DOi and the compensation voltage DO2.
1? The control signal DO4 is obtained as an output voltage. The control signal DO4 has a waveform similar to that of the converted voltage 1101, and the signal is in the lead. In this case, -1 total current To and i control current 10 coincide in time, and power supply voltage fluctuation △V is 0.
become.

Returning to FIG. 2, the pulse generator that receives the control signal DO4 generates a pulse P together with the secondary voltage V of the transformer, and sends a firing pulse to the thyristor 80R of the flicker absorber ν to control it. Control current lPO? At this time, if the flicker absorption device uses a reactor, the firing angle of the thyristor SOR is controlled, and if the flicker absorption device uses a capacitor, the number of fired thyristors SOR is controlled.

Synchronous compensator 1901. S02. operate at the same time,
Load L3. L4. When . . . operates, the waveforms and circuit actions described above are performed simultaneously and added. Furthermore, the synchronous compensator SO1゜S02. Although only two are mentioned in the text, there is no limit to the number.

As described above, according to the present invention, a load that fluctuates drastically can be dealt with using a predictive control method, and a load that fluctuates slowly or has a large number of small fluctuations can be handled by controlling the total current. Because of this control, it is possible to create a device that has a high overall 7-linoka absorption effect.

[Brief explanation of the drawing]

FIG. 1 is a single line diagram of power supply equipment in which the device of the present invention is installed. The symbol explanation is as follows. F: Flicker absorption device, PO: Control current flowing through the flicker absorption device, PT: Transformer, ■: Secondary voltage of transformer, OT...
...Current transformer ri, L2゜LM, II4. ...Load, OTl, OT2. ...Current transformer, 10.20
...φ current transformer OT1. OT2. Secondary current of B1
．． B2. ...Load 11. Prediction signal extracted from L2 FIG. 2 is a block diagram showing an embodiment of the present invention. The symbols are as follows. aV...converter, 3F...5-phase synthesizer, PO...pa μ; g generation N, san...
・Thyristor, 801°E102...Synchronous compensator, DOl...Conversion voltage. DO4... Control signal, P... Pa/L'
Compensation voltage No. 3.4, 5. The figure is a timing chart for explaining the present invention. In this figure, ΔV is the variation in the power supply voltage. Other symbol explanations are as described above. Patent applicant Daisuke Inoue

Claims (1)

Scope of Claims: As shown in FIG. 1, (1) a current transformer OT for detecting the total load current, a transformer pT for detecting the power supply voltage, and a particularly large load L1. L2. current transformer OT1', OT that detects the current of
2. to be installed. (2) Load 11. L2. The prediction signal B1 rises and falls 20 to 90 degrees faster than when the load current actually flows.
．． B2 is loaded v1. 'Lz, it's more like taking revenge. (3)' A 7-resoka absorption device r is installed on the power supply side from the current transformer OT that detects the total load current, which controls the firing of the thyristor to flow a reactive current FO according to the load current. (4)゛As shown in Figure 2, the secondary current T01 of current transformer OT and the secondary voltage V of transformer FT
is added to the converter Ov to create the control voltage DO1 for each phase, and the secondary current 10, 20 of the current transformer OT1゜O12,
．． and prediction signal 111. B2. The synchronous compensator 801,
802 and the resulting compensation signals, respectively, DO2°B03. to make. (5) These compensation signals, DO2, Do3 . 3 phase combiner 5
1F, and as a result, the load L1. L2. Obtain a control signal D04° for each phase in which only the signal of To be used as the firing pulse of the thyristor SOR in the Above, (1) (2), (3), (4), (5
) Control circuit for a 7-linoka absorption device characterized by using the following items at the same time