JP3321891B2 - Static reactive power adjustment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of controlling a reactive current in a power system such as a distribution line by controlling a current flowing in a reactor by a switching element such as a thyristor and continuously and variably controlling the reactive power. , For adjusting the voltage.

[0002]

2. Description of the Related Art FIG. 3 shows a single-line diagram of a conventional reactive power adjusting device in which a reactor 1, a reactor 2 and a capacitor are connected in series, and a thyristor connected in anti-parallel to a connection point between the reactor 1 and the reactor 2 is connected. . In FIG. 3, 1 is a reactor, 2 is a reactor, 3 is a capacitor, and 4 is a thyristor connected in anti-parallel. In the conventional reactive power adjusting device configured as described above, the capacity at the commercial frequency obtained by adding the reactor 1 and the reactor 2 to the capacity of the capacitor 3 is set to 20% or less. By controlling the firing phase angle of the thyristor 4 in this reactive power adjusting device, it was possible to control from the leading reactive power to the lag reactive power. FIG. 4 is a diagram illustrating the control reactive power with respect to the thyristor firing angle of the reactive power adjusting device. As is apparent from this figure, the reactive power advances with respect to the firing phase angle of the thyristor 4 and can be continuously controlled from reactive power to delayed reactive power. FIG. 5 is a diagram showing the relationship between the operating reactive power of the conventional reactive power adjusting device and the current flowing through the thyristor. That is, it shows the relationship between the amount of reactive power and the current flowing through the thyristor when controlling from the leading reactive power to the lag reactive power. From this figure, it can be seen that the current flowing through the thyristor increases as the delayed reactive power increases. As for the thyristor, there is no thyristor of a single usable voltage suitable for the high voltage used in forming the reactive power adjusting device shown in FIG. Therefore, a thyristor with a low voltage rating is used.
Since the voltage is high, a plurality of them are connected in series and used. FIG. 6 is a configuration diagram of a thyristor portion of a conventional reactive power adjusting device. That is, it is a diagram for explaining a conventional thyristor and a peripheral circuit. In FIG. 6, the snubber circuit portion 5 mainly composed of a resistor and a capacitor connected in parallel to the thyristor also requires a number of parts corresponding to the number of thyristors, and the ignition circuit 6 for igniting the thyristor also has the number of thyristors. Will be needed. For example, in the case of a reactive power adjusting device used for a 6.6 KV distribution line, 10 thyristors rated at 4 KV are connected in series in consideration of a lightning surge on the distribution line. Further, the ignition circuit of the thyristor and the ignition circuit are complicated and expensive in consideration of the dielectric strength of the thyristor. For this reason, the configuration of the thyristor part becomes significantly complicated, and the specific gravity relating to the assembly of the thyristor part in the assembly work of the conventional reactive power adjusting device is extremely large. Price increase.

FIG. 7 is a diagram showing the relationship between the reactive power and the harmonic current. As shown in FIG. 7, the harmonic current increases as the delay reactive power increases. It is necessary to reduce the harmonic current as much as possible, and from this point, the control range of the delay reactive power has been narrowed. Further, in order to further reduce the harmonic current, a device for absorbing harmonics such as a harmonic filter is connected in parallel with the conventional reactive power adjusting device. The connection of this device could significantly increase the price.

[0004] These facts show that there is a limit to the usable range of the reactive power adjusting device shown in FIG.

[0005]

Since the conventional reactive power adjusting device is used at a high voltage, the thyristor portion has a complicated structure, so that the number of steps of the assembling work is large and the price is expensive. In addition, the harmonic current is as shown in FIG. 7. Therefore, when industrially practically used, both the control range of the delay reactive power amount is the harmonic current, and the thyristor portion is an adverse effect in expanding the application. .

The present invention has been made to solve the above-mentioned problems of the conventional reactive power adjusting device.
The control range of the lag reactive power has been reduced to the level where it is not necessary to install a harmonic filter in parallel with the control range of the lead reactive power. It is intended to improve the practicality of the reactive power adjusting device by greatly reducing the number of points and greatly reducing the price.

[0007]

SUMMARY OF THE INVENTION A reactive power regulator according to the present invention reduces a high voltage including a reactance component to a low voltage in a high voltage power system such as a distribution line, and converts the low voltage into an AC transformer. the secondary side is connected to <br/> the first reactor and the capacitor in series, an AC transformer, the secondary side of the AC transformer
A thyristor connected in anti-parallel is connected to a connection point with the connected first reactor, and a reactor included in the AC transformer is connected.
To the reactive power adjustment circuit as the second reactor
In the apparatus with built-in for that capacitance, the AC transformer reactance to the AC transformer in the first commercial frequency and reactance component was <br/> sum of the reactor that is connected to the secondary side of the by capacity was 30% or more
The thyristor current is reduced and the harmonic current is suppressed .

[0008]

[Action] An AC transformer, a reactor, and a capacitor are connected in series, and the total sum of the reactance of the AC transformer and the reactance of the reactor is 30% of the capacitance of the capacitor. The reactive power control range of the reactive power adjusting device is large. Expanded to.

[0009]

FIG. 1 is a diagram for explaining the configuration of an embodiment of a reactive power adjusting device according to the present invention. 11 is an AC transformer including a reactance component, 12 is a reactor 2 connected to the secondary side of the AC transformer 11, 13 is a capacitor, and 14 is a thyristor connected in anti-parallel. For example, if the primary side of an AC transformer is connected to a 6.6KV distribution line and the secondary side voltage is 660V, the rated voltage of the thyristor is 4K.
V may be employed, and the configuration of the thyristor portion is a set of thyristors 14 connected in anti-parallel as shown in FIG.
And two firing circuits 16 and one snubber circuit 15, which are very simple as compared with FIG. 6, the number of parts is reduced, and the assembling work is simplified. On the other hand, the current flowing through the thyristor increases by lowering the voltage from 6.6 KV to 660 V. However, in terms of price, one thyristor rated at 660 V and having an increased current capacity is used instead of using ten thyristors. However, in general, the price is reduced, and the price is greatly reduced by reducing the number of components. Also, the voltage between the ignition circuit and the thyristor is significantly lower than in the past, so that a low-cost configuration is possible in terms of insulation design.

FIG. 8 is a diagram illustrating the comparison of the currents flowing through the thyristors of the conventional reactive power adjusting device and the reactive power adjusting device of the present invention. That is, the conventional reactive power adjusting device is 660 V
FIG. 7 is a diagram showing a comparison between the case where the power supply is used at the same voltage and the case where the secondary voltage of the reactive power adjusting device of the present invention is set to 660V.
In the conventional case, the horizontal axis is the capacitance ratio at the commercial frequency obtained by adding the reactor 1 and the reactor 2 to the capacitor capacity

[0011]

(Equation 1)

In the case of the present invention, the horizontal axis represents the capacitance ratio at the commercial frequency obtained by adding the reactance of the transformer to the capacitance of the capacitor and the reactance of the reactor 12 connected to the secondary side of the transformer. The vertical axis indicates the thyristor current. The data shown in the figure is based on the capacitance corresponding to the reactance of the reactor 1 or the AC transformer with respect to the capacitance of the capacitor and the capacitance at the commercial frequency obtained by adding the reactor 2 or the reactor 12. It is data of an example at the time of 50% power operation. The intersection A between the straight line (a) parallel to the horizontal axis and the curve at the time of 100% delayed reactive power operation indicates the thyristor current value during operation of the conventional reactive power adjusting device.
The intersections of the straight line (b) parallel to the horizontal axis and the operating curves of the delayed reactive power of 50% and 100% are indicated by B and C, respectively, where B is the thyristor during the operation of the conventional reactive power adjusting device. C indicates the thyristor current during the operation of the reactive power adjusting device according to the present invention.

From this figure, it can be seen that the reactive power adjusting device according to the present invention greatly reduces the current flowing through the thyristor when operating at the same reactive power, as compared with the conventional reactive power adjusting device. Thus, the thyristor current at the time of 50% delayed reactive power operation and the thyristor current at the time of 100% delayed reactive power operation of the reactive power adjusting device according to the present invention are substantially at the same level. This is a thyristor that can control the delay reactive power control range up to 50% with the conventional reactive power adjustment device, and the delay reactive power adjustment range can be up to 100% with the reactive power adjustment device of the present invention, so that it is industrially practical. The range has been greatly expanded.

FIG. 9 is a diagram showing a comparison of harmonic currents with respect to reactive reactive power of the conventional reactive power adjusting device and the reactive power adjusting device of the present invention. In the figure, a curve (a) shows a conventional harmonic current, and (b) shows a harmonic current of the reactive power adjustment value according to the present invention. From this figure, it can be seen that the harmonic current according to the present invention is significantly reduced as compared with the conventional device. As a result, the reactive power adjusting device according to the present invention can be installed in a power system without installing a harmonic filter in parallel, and the practical value is greatly improved.

FIG. 10 is a diagram comparing the effective capacity of the reactor 2 of the conventional reactive power adjusting device with respect to the operating reactive power of the reactor 12 of the reactive power adjusting device according to the present invention. The effective capacity means that the current flowing through the reactor 2 or the reactor 12 includes many harmonic currents in addition to the current of the commercial frequency component. This is the capacity including the harmonic current. In the figure, the curve (a) shows the effective capacity of the conventional reactor 2 and the curve (b) shows the effective capacity of the reactor 12 of the reactive power adjusting device of the present invention. This figure shows that the effective capacity of the reactor 12 according to the present invention is significantly reduced as compared with the conventional device. This leads to a reduction in noise due to harmonic current contained in the current flowing through the reactor 12 while exhibiting a small size, light weight and low cost.

As described above, the reactive power adjusting device according to the present invention greatly expands the delay reactive power control range as compared with the conventional reactive power adjusting device at the same current capacity of the thyristor used in the present device, The current is also greatly reduced, and the effective capacity of the reactor 2 used in this device is also reduced,
The industrial value of use of the reactor 2 is increased due to effects such as reduction in size, weight, and cost of the reactor 2 and reduction in noise.

[0017]

According to the present invention, the high voltage to a low voltage
An AC transformer including a reactance component, a reactor and Sandensa connected in series to the secondary side of the AC transformer, exchange
Connect the anti-parallel connected thyristors to the junction of the flow transformers and reactors configured, with respect to the capacity of the capacitor, the commercial frequency and reactance component by adding the reactance and re Akutoru included in AC transformer Is 30% or more , the number of components in the thyristor portion constituting the reactive power adjusting device is reduced, so that assembling work is reduced and material costs are reduced. Further, the current flowing through the thyristor is also reduced. Further, the harmonic current is reduced, and the influence on distribution lines and the like is reduced. Further, with respect to conventional reactor 2, there are effects such as effective capacity of the reactor 12 of the present invention is reduced, industrial utility is increased.
Further, the present invention is similarly applicable to an extra high voltage power system.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of a reactive power adjusting device according to the present invention.

FIG. 2 is a diagram illustrating a configuration of a thyristor portion of the present invention.

FIG. 3 is a single-line diagram of a conventional reactive power adjusting device.

FIG. 4 is a diagram showing control reactive power with respect to the thyristor firing angle of the reactive power adjusting device.

FIG. 5 is a diagram showing the relationship between the operating reactive power of the conventional reactive power adjusting device and the current flowing through the thyristor;

FIG. 6 is a diagram showing a configuration of a thyristor portion of a conventional reactive power adjusting device.

FIG. 7 is a diagram showing a relationship between reactive reactive power and harmonic current.

FIG. 8 is a diagram illustrating a comparison between currents flowing through thyristors of a conventional reactive power adjusting device and a reactive power adjusting device of the present invention.

FIG. 9 is an explanatory diagram of the effect of the device of the present invention comparing the harmonic current with respect to the operating reactive power of the conventional reactive power adjusting device and the reactive power adjusting device of the present invention.

FIG. 10 is a diagram comparing the effective capacity of the reactor 2 of the conventional reactive power adjustment device with respect to the operating reactive power of the reactor 12 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reactor 1 11 AC transformer 12 Reactor 2 13 Capacitor 14 Antiparallel connection thyristor 15 Snubber circuit 16 Thyristor ignition circuit

Continued on the front page (72) Inventor Yukio Arikawa 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. References JP-A-3-113521 (JP, A) JP-A-2-50725 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G05F 1/70 H02J 3/18

Claims (2)

(57) [Claims] And 1. A AC transformer for decreasing the high voltage including a reactance component to the low voltage, a first reactor and a capacitor connected in series to the secondary side of the AC transformer, the
Connect the anti-parallel connected thyristors in the connection point between the the AC transformer first reactor configured, the AC transformer
Reactance contained in the vessel as the second reactor
A reactive power adjusting device incorporated in a reactive power adjusting circuit . To the capacity of 2. A capacitor, the capacity of the commercial frequency of the reactance component by adding the first reactor which is connected to the secondary side of the reactance to the AC transformer included in the AC transformer 30% Sairis
2. The reactive power adjusting device according to claim 1 , wherein the control current is reduced and the harmonic current is suppressed .