JPS63314144A - Series connected type voltage variation compensating device - Google Patents

Abstract

PURPOSE:To enable adding a certain voltage to a load stably, even if a large voltage variation is generated in an electric power system, by connecting first and second compensating power sources into a feeder route via a coupling transformer. CONSTITUTION:Secondary windings of first and second coupling transformers 3, 4 are inserted in series into a feeder route from an electric power system 1 to a load 2. A first compensating power source 5 with a small capacity is connected with the primary winding of said first coupling transformer 3 while a second compensating power source 6 with a large capacity is connected with the primary winding of said second coupling transformer 4. A voltage variation of the electric power system 1 less than a given percent of the normal voltage of said system 1 is compensated by said first compensating power source 5 alone and that exceeding said given percent is compensated by said second compensating power source 6 in cooperation with the first compensating power source 5.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is applicable to power systems that are damaged within a short period of about 0.1 seconds due to ground faults, short circuits, etc. of power transmission lines caused by lightning strikes on transmission lines, etc. It compensates for large voltage fluctuations (instantaneous voltage drops) exceeding, for example, about 10% of the power system's normal voltage, as well as minute voltage fluctuations such as voltage waveform distortion and voltage flicker that are less than about 10% of the power system's normal voltage. This invention relates to a series-type voltage fluctuation repair device for preventing adverse effects on the load of a house.

[Conventional technology]

Conventionally, so-called uninterruptible power supplies (constant-frequency constant-voltage devices that combine a battery and an inverter circuit) have been used as a countermeasure against instantaneous voltage drops in power systems due to ground faults and short circuits on power lines caused by lightning strikes, etc. is used.

This constant frequency voltage regulator normally converts the power system voltage into DC voltage, converts this DC voltage into AC voltage using an inverter circuit, applies AC voltage to the load, and when a failure occurs in the power system, the DC voltage is AC voltage is applied to the load from a battery connected in parallel to the inverter circuit.

Such constant frequency voltage regulators keep the inverter circuit running at all times in the event of an extremely rare power system accident, and generally operate at 15 to 20% of the rated capacity.
The drawback was that it resulted in considerable power loss and increased operating costs.

A series-type instantaneous voltage drop compensator has already been proposed that can solve such problems and compensate for instantaneous voltage drops in the power system without increasing operating costs.

As shown in FIG. 3, this series-type instantaneous voltage drop compensator is constructed by inserting and connecting the secondary winding of a coupling transformer 4 into the power supply path from the power system 1 to the load 2, and connecting the secondary winding of the coupling transformer 4 to the A large-capacity compensation power supply 6 is connected to the S line, and a bypass switch 7 made of a thyristor is connected. When the voltage V of the power system 1 is normal, the bypass switch 7 is turned on and the power system 1 is connected to the coupling transformer. 4, and when an instantaneous voltage drop of more than 10% of the normal voltage occurs in the voltage V of the power system 1, the bypass switch 7 is turned off, and the By applying a compensation voltage VH corresponding to the voltage drop in the power system 1 from Regardless of the voltage, a constant voltage is applied.

In this case, in preparation for the occurrence of an instantaneous voltage drop, the compensation power supply 6 charges the capacitor by rectifying, for example, the voltage of the power system I and adding it to the capacitor, and supplies the energy stored in the capacitor to the inverter circuit. By doing so, a compensation voltage V is generated. In addition, the compensation power supply 6 includes the normal voltage of the power system 1 and the current voltage v.
It also includes a circuit that detects the voltage difference between H and H. Furthermore, although not shown in the drawings, this series type instantaneous voltage drop compensator has a voltage drop detection circuit that detects the occurrence of a drop of more than 10% of the normal voltage of the power system 1 VS. There is.

This series-type instantaneous voltage drop compensator detects when an instantaneous voltage drop exceeding, for example, 10% of the normal voltage of the power system I, operates the compensation power supply 6 to compensate for the voltage drop. Therefore, there is an advantage that there is almost no power loss when the power system 1 is normal, and the operating cost is low.

[Problem that the invention seeks to solve]

This series type instantaneous voltage drop compensator is configured to perform voltage drop compensation only when an instantaneous voltage drop exceeding, for example, 10% of the normal voltage of the power system 1, V, occurs. Even if slight voltage fluctuations not exceeding 10% of the current voltage, ie, voltage waveform distortion, voltage fluctuations, etc., occur, it has not been possible to compensate for them. That is, in this series type instantaneous voltage drop compensator, the voltage vs of the power system 1 is subject to minute voltage fluctuations A that are less than 10% of the normal voltage such as voltage waveform distortion and voltage flicker as shown in FIG. 4(a).
1. If there is an instantaneous voltage drop B1 that exceeds A2 and 10% of the normal voltage, the compensation power supply 6 detects it when the current voltage of the power system 1 drops by more than 10% of the normal voltage. As a result, a compensation voltage vH as shown in FIG. 4 fbl is output. Therefore, as shown in Fig. 4(C), the load voltage VL applied across the load 2 is compensated for the instantaneous voltage drop B1, but the minute voltage fluctuations A, , A2 are not compensated for at all. , 1 voltage v of power system 1
The minute voltage fluctuations A, , A2 at s appear as they are in the load voltage vL as voltage fluctuations CI, C2.

In addition, in FIG. 4 (al, (C1), the broken line indicates the voltage waveform during normal operation.

In this way, if voltage fluctuations in the power system I are directly applied to the load 2, there is a risk that the load 2 of the consumer will be adversely affected.

Therefore, an object of the present invention is to be able to stably apply a constant voltage to a load even if a large voltage fluctuation exceeding a predetermined percentage of the normal voltage occurs in the power system, and to To provide a series type voltage fluctuation compensator capable of applying a stable voltage without fluctuation to a load even if a minute voltage fluctuation of less than a predetermined percentage occurs, and also capable of keeping operating costs low.

[Means for solving problems]

The series type voltage fluctuation compensator of the present invention has a primary winding in which a secondary winding is inserted in series in the power supply path from the power system to the load.
and a second coupling transformer, a small capacitor connected to the primary winding of the first coupling transformer and solely compensating for voltage fluctuations in the power system below a predetermined percentage of the normal voltage of the power system. a first compensating power source connected to the primary winding of the second coupling transformer to cooperate with the first compensating power source to prevent voltage fluctuations exceeding a predetermined percentage of the normal voltage of the power system; a large-capacity second compensating power source for compensating; and a bypass connected in parallel to the secondary winding of the second coupling transformer and shutting off when a voltage fluctuation exceeding a predetermined percentage of the normal voltage of the power system occurs. Equipped with a switch.

[Effect]

According to the configuration of the present invention, the secondary windings of the first and second coupling transformers are inserted in series in the power supply path from the power system to the load, and the secondary windings of the first coupling transformer are connected to the primary windings of the first coupling transformer. A first compensating power source with a small capacity is connected, and a second compensating power source with a large capacity is connected to the primary winding of the second coupling transformer, and the power is lower than a predetermined percentage of the normal voltage of the power system. Voltage fluctuations in the grid are compensated by the first compensation power supply alone, and voltage fluctuations exceeding a predetermined percentage of the normal voltage of the power grid are compensated by the second compensation power supply in cooperation with the first compensation power supply. Therefore, even if large voltage fluctuations exceeding a predetermined percentage of the normal voltage occur in the power grid, a constant voltage can be stably applied to the load, and even if the power grid experiences a slight voltage fluctuation that is less than a predetermined percentage of the normal voltage, Even if voltage fluctuations occur, a stable voltage without fluctuations can be applied to the load.

Moreover, the large-capacity second compensation power supply operates only when a voltage fluctuation exceeding a predetermined percentage of the normal voltage of the power system occurs, and the small-capacity first compensation power supply operates all the time. Therefore, operating costs can be kept low.

〔Example〕

An embodiment of the present invention will be described based on FIGS. 1 and 2. That is, as shown in FIG. 1, this series type voltage fluctuation compensator connects the secondary windings of the first and second coupling transformers 3 and 4 in series in the power supply path from the power system 1 to the load 2. A small-capacity first compensation capacitor 1i5 is connected to the primary winding of the first coupling transformer 3, and a large-capacity second compensation capacitor 1i5 is connected to the primary winding of the second coupling transformer 4. A power supply 6 is connected and a bypass switch 7 is also connected.

When a slight voltage fluctuation that is less than a predetermined percentage (for example, 10%) of the normal voltage occurs in the voltage (1) of the power system 1, the large-capacity second compensation power supply 6 is not activated and the via 1 is By turning on the switch 7 and bypassing the secondary @ line of the second coupling transformer 4, the small-capacity first compensating power supply 5 alone compensates for fluctuations in the voltage of the power system 1,
The voltage of the power system l is set to a predetermined percentage of the normal voltage (
For example, when an instantaneous voltage drop exceeding 10% occurs, the bypass switch 7 is turned off and the second compensation power supply 6 is activated to cooperate with the first compensation power supply 5 to compensate for the voltage drop. It has become.

As a result, the voltage of the power grid l is 10% of the normal voltage.
When there is a slight voltage fluctuation that is less than Even if a voltage fluctuation of less than 10% of the normal voltage occurs in the voltage vs of the power system l, no voltage fluctuation occurs in the load voltage ■, across the load 2, and the voltage ■s of the power system l has a voltage fluctuation of less than 10% of the normal voltage. When an instantaneous voltage drop of 10% occurs,
The sum of the voltage V of the power system 1, the compensation voltage Vfll of the first compensation power source 5, and the compensation voltage VIi2 of the second compensation amount s6 is applied to the load 2, and the voltage V of the power system 1 is added to the load 2. Even if an instantaneous voltage drop of more than 10% of the normal voltage occurs in the voltage vs, no voltage fluctuation occurs in the load voltage vL across the load 2.

In this case, the compensating power supply 5.6 charges the capacitor by rectifying the voltage V of the power system L and adding it to the capacitor in preparation for the occurrence of voltage fluctuation, and transfers the energy stored in the capacitor to the inverter circuit. By supplying the compensation voltage V! It is designed to generate illVH2. Further, the compensation types flS and S are also equipped with a circuit that detects the difference voltage between the normal voltage of the power system 1 and the current voltage immediately before the compensation point. Furthermore, although not shown in the figure, this series-type instantaneous voltage drop compensator
The voltage drop detection circuit detects the occurrence of a voltage drop exceeding, for example, 10% of the normal voltage of s.

Also, the power system 1 of the first and second coupling transformer 3.4
The order of insertion in the power supply path from
A second coupling transformer 4 connected to a large-capacity compensation power source 6 is placed on the load 2 side, and when the voltage fluctuation of the power system 1 exceeds 10% of the normal voltage, First, the first compensating power source 5 with a small capacity compensates for the amount that can be compensated according to its capacity, and the remainder is compensated with the second compensating power source 6 with a large capacity. compensation voltage VH1
, VH2 is controlled so that the generation ratio is, for example, about 1:5.

The manner in which the iron and voltage fluctuations are compensated for will be explained with reference to FIG. 2 and B. Now, in the voltage of power system 1, voltage waveform distortion, voltage flicker, etc., as shown in Figure 2+a), occur during normal operation.
If there is a slight voltage fluctuation A1°A2 below 0% and an instantaneous voltage drop B1 exceeding 10% of the normal voltage,
The first compensation power supply 5 compensates for all minute voltage fluctuations A, A2, and the compensation voltage V□1 becomes as shown in FIG. 2 (C1), and the instantaneous voltage drop B1 is partly (
For example, about 15 to 20%), the compensation voltage ■□1 becomes as shown in Figure 2 (C1. On the other hand, the second compensation type tA6
does not compensate for minute voltage fluctuations A, , A2 at all,
Compensate only for the instantaneous voltage drop B1, and compensate for the compensation voltage VB2
(in Figure 2). Therefore, the load voltage vL across the load 2 does not change at all even if there is a voltage fluctuation in the voltage V of the power system 1 as shown in Figure 2 (dl). , the broken line shows the voltage waveform of the power system 1 during normal operation, and the broken line in FIG.

The series type voltage fluctuation compensator of this embodiment has the secondary windings of the first and second coupling transformers 3 and 4 inserted in series in the power supply path from the power system 1 to the load 2. Coupling transformer 3
A small-capacity first compensation power source 5 is connected to the primary winding, and a large-capacity second compensation power source 6 is connected to the primary S line of the second coupling transformer 4 to ensure that the power system 1 is normal. The first compensating power source 5 alone compensates for voltage fluctuations in the power system 1 that are less than a predetermined percentage of the normal voltage, and cooperates with the first compensating power source 5 to compensate for voltage fluctuations that exceed a predetermined percentage of the normal voltage of the power system 1. In order to compensate with the second compensation power source 6, the power system l
A constant voltage can be stably applied to the load 2 even if a large voltage fluctuation exceeding a predetermined percentage of the normal voltage occurs in the power system 1, and a slight voltage fluctuation below a predetermined percentage of the normal voltage can be applied to the power system 1. Even if this occurs, a stable voltage without fluctuation can be applied to the load 2.

Moreover, the large-capacity second compensating power source 6 operates only when a voltage fluctuation exceeding a predetermined percentage of the normal voltage of the power system l occurs, and the small-capacity first compensating power source 6 operates all the time.
Since only the compensation power source 5 is required, operating costs can be kept low.

Note that in the above embodiment, the first and second coupling transformers 3
．． 4, the first coupling transformer 3 is placed on the power system 1 side, and the second coupling transformer 4 is placed on the load 2 side. A coupling transformer 4 is arranged on the power system 1 side, and a small capacity first coupling transformer 3
may be placed on the load 2 side; in this case, the power system 1
The instantaneous voltage drop exceeding 10% of the normal voltage of voltage ■ is roughly compensated for by the large-capacity second compensation power supply 6, and the small-capacity first compensation power supply 5 is used to finely compensate for the above voltage fluctuation. I will do it.

〔Effect of the invention〕

According to the series type voltage fluctuation compensator of the present invention, the secondary windings of the first and second coupling transformers are inserted in series in the power supply path from the power system to the load, and the first coupling transformer A first compensating power source with a small capacity is connected to the primary winding, and a second compensating power source with a large capacity is connected to the primary winding of the second coupling transformer, and a predetermined normal voltage of the power system is established. The first compensating power supply alone compensates for voltage fluctuations in the power system that are less than 10%, and the second compensating power supply works together with the first compensating power supply to compensate for voltage fluctuations that exceed a predetermined percentage of the normal voltage of the power system. Because the power supply compensates, it is possible to stably apply a constant voltage to the load even if the power grid experiences large voltage fluctuations that exceed a predetermined percentage of the normal voltage, and it also allows the power grid to maintain a constant voltage that exceeds a predetermined percentage of the normal voltage. A stable voltage without fluctuation can be applied to the load even if slight voltage fluctuations occur.

Moreover, the large-capacity second compensation power supply operates only when a voltage fluctuation exceeding a predetermined percentage of the normal voltage of the power system occurs, and the small-capacity first compensation power supply operates all the time. Therefore, operating costs can be kept low.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.
2 is a waveform diagram of each part in FIG. 1, FIG. 3 is a block diagram showing the configuration of a conventional series type instantaneous voltage drop compensator, and FIG. 4 is a waveform diagram of each part in FIG. 3. DESCRIPTION OF SYMBOLS 1... Power system, 2... Load, 3... First coupling transformer, 4... Second coupling transformer, 5... First compensation power source, 6... ...Second compensation power supply, 7...pi/? Susui Nochi 1-11 Electric power system 2-m-9 Load 3-11 First coupling transformer 4-11 Second coupling transformer 5-11 First compensation power supply 6--- To the second compensation power supply 7---! ? Suzuitte 1st figure 2nd figure

Claims (1)

[Claims] first and second coupling transformers each having a secondary winding inserted in series in a power supply path from the power system to the load; and connected to the primary winding of the first coupling transformer, the power system a small-capacity first compensation power supply that independently compensates for voltage fluctuations in the power system that are less than a predetermined percentage of the normal voltage of the power system; a large-capacity second compensating power supply that cooperates with the first compensating power supply to compensate for voltage fluctuations exceeding a predetermined percentage of the normal voltage; and parallel to the secondary winding of the second coupling transformer. A series type voltage fluctuation compensator comprising: a bypass switch connected to the power system to shut off when a voltage fluctuation exceeding a predetermined percentage of the normal voltage of the power system occurs;