JP2815284B2 - Voltage control method for power supply system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage control method for a power supply system.

[0002]

2. Description of the Related Art Conventionally, external power is supplied through a substation as a driving source for various power facilities in a manufacturing facility such as a steelworks. As shown in FIG. In general, the voltage is changed to a predetermined voltage by a tap switching transformer 3 provided between the power supply system 2 and the power supply system 2.

Normally, electrical equipment and facilities used for the load system 2 are guaranteed to have a normal performance as a permissible value up to ± 10% according to JIS or JEC standards. However, on the user side, in order to ensure stable operation or high-quality operation of these devices and equipment, voltage fluctuations at higher-level substations are, for example, ± 5 It is generally managed within%.

[0004] Figure 4, wherein at illustrates a schematic configuration of a tap-changing transformer 3, switching on the primary side coil 4 of the primary voltages V ₁ is connected to an external power system 1 is supplied Taps are provided in a plurality of stages, and are operated by a secondary voltage V ₂ detected by a voltage detector 7 provided on the secondary coil 6 side via a dead zone-adjusted voltage adjusting relay 8. 9 enables switching. At this time,
It is common to to have a dead zone with respect to the reference voltage V _2S The secondary voltage V ₂ which is controlled by the dead zone with a voltage adjusting relay 8, the voltage adjustment operation if within this dead band into the secondary voltage V ₂ falls within Is a control method that is regarded as completed.

[0005]

However, the above-mentioned prior art has the following problems.
In other words, the control is performed when the secondary voltage goes out of the dead zone, and the control ends at the moment when the voltage value returns to the dead zone. It is possible to do so.

In order to prevent such a phenomenon, for example, it is conceivable to widen the width of the dead zone. It is thought that the frequency of deviating from the dead zone will be reduced. May increase, and a new problem arises in that the accuracy of the secondary voltage supplied to the load system with respect to the reference voltage is reduced.

Conversely, if the width of the dead zone is reduced, a cycle in which the secondary voltage deviates from or returns to the dead zone frequently occurs, that is, a so-called hunting phenomenon occurs. There is a possibility that another trouble such as exhaustion of the battery will occur. SUMMARY OF THE INVENTION An object of the present invention is to provide a voltage control method for a power supply system that solves the above-mentioned problems of the related art.

[0008]

According to the present invention, there is provided a method of controlling a voltage of a power supply system using a tap switching transformer and a voltage regulating relay, comprising: measuring a secondary voltage of the tap switching transformer; When the voltage value deviates from a preset dead band of the reference voltage, the tap switching of the tap switching transformer is performed so that the voltage falls within a predetermined allowable range smaller than the width of the dead band of the reference voltage value. This is a characteristic voltage control method for a power supply system.

[0009]

According to the present invention, first, a secondary voltage is measured and the voltage value is compared with a preset upper and lower limit value of a dead zone.
When it is determined that the dead zone has been deviated, a deviation from the reference voltage is calculated and obtained, taps are switched in accordance with the deviation, and a predetermined allowable range smaller than the width of the dead zone from the reference voltage is entered. , The tap change is stopped, so that the control does not immediately fall out of the dead zone as in the conventional example.

The procedure of the present invention will be described in detail with reference to FIG. The upper and lower limits α, β of the dead zone with respect to the reference voltage V _{2S in} advance
And an allowable value γ for the reference voltage V _2S is set.
Here, the allowable value γ is set to a value sufficiently smaller than the width α-β of the dead zone. First, it is determined by the following equation (1) whether the secondary voltage V ₂ has exceeded the dead zone upper limit α.

V ₂ ≧ α (1) If the expression (1) does not hold, that is, if it does not exceed, the process proceeds to the next step. If it is determined that it has exceeded, the process proceeds to the next next step. Next, it is determined whether the secondary voltage V ₂ exceeds the dead zone lower limit value β by the following equation (2).

V ₂ ≦ β (2) If not exceeded, return to the previous step. If it is determined that it has exceeded, the process proceeds to the next step. The tap is switched according to the step or the instruction of the step. It is determined whether or not the tap switching result satisfies the allowable value γ according to the following equation (3).

| V ₂ −V _2S | ≦ γ (3) If the expression (3) is not satisfied, the process returns to the previous step and continues the tap switching operation until the expression is satisfied. If the equation (3) is satisfied, the process returns to the first step and prepares for the next voltage fluctuation.

[0014]

Embodiments of the present invention will be described below.
As shown in FIG. 1, the tap switching transformer 3A of the present invention is provided with a voltage control device 10. The voltage control device 10 has upper and lower limit values α,
β and the allowable value γ are set in advance, and then the steps and the steps are sequentially performed.
Is operated to switch the tap, and control is continued so that the voltage fluctuation in the step falls within the range of the allowable value γ.

FIG. 2 shows a change in voltage fluctuation when the present invention is applied when the secondary voltage V ₂ exceeds the dead zone upper limit value α. For comparison, the characteristics according to the conventional example are shown by dotted lines. As shown in this figure, whereas the frequent control and out of the vicinity of the dead zone upper limit value α in the conventional example have been made, since would fit around one sputum reference voltage V _2S in the present invention method, subsequent It can be seen that even if there is a voltage fluctuation, the voltage changes slowly and good voltage control is performed.

In the above embodiment, the dead zone function has been described as being provided in the voltage control device 10. However, the present invention is not limited to this. For example, as in the conventional example, the voltage adjustment relay 8 with a dead zone is provided. May be used, or the dead zone function may be configured independently.

[0017]

As described above, according to the present invention, 2
The next voltage is measured, and the voltage value is compared with a preset upper and lower limit value of a dead band. When it is determined that the voltage value is out of the dead band, a deviation from a reference voltage is calculated and obtained. Since the switching is performed and the tap switching is stopped at a stage when a predetermined allowable range smaller than the width of the dead zone from the reference voltage is reached, stable and accurate voltage control can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a change in voltage fluctuation when the present invention is applied.

FIG. 3 is an explanatory diagram of a conventional power supply system.

FIG. 4 is a schematic diagram showing a configuration of a conventional tap switching transformer.

FIG. 5 is a flowchart showing a procedure of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 External power system 2 Load system 3A Tap change transformer 4 Primary coil 5 Switching tap 6 Secondary coil 7 Voltage detector 8 Voltage adjustment relay with dead zone 9 Tap changer 10 Voltage controller 11 Voltage adjustment relay

Claims (1)

(57) [Claims] 1. A method of controlling a voltage of a power supply system using a tap switching transformer and a voltage regulating relay, wherein a secondary voltage of the tap switching transformer is measured, and the measured voltage value is set to a predetermined reference. If the voltage is outside the dead zone,
A voltage control method for a power supply system, wherein the tap switching of the tap switching transformer is performed so that the reference voltage value falls within a predetermined allowable range smaller than the width of the dead zone.