JP3319010B2 - 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 for controlling a reactive current in a power system such as a distribution line by controlling a current flowing through a reactor by a thyristor or the like and continuously variably controlling the reactive power, and for controlling a voltage. It is used for adjustment.

[0002]

2. Description of the Related Art FIG. 1 shows a single-line diagram of a conventional reactive power regulator 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. 1, reference numerals 1 and 2 denote reactors, 3 denotes a capacitor, and 4 denotes a thyristor connected in anti-parallel. In the conventional reactive power adjusting device configured as described above, the reactor 1
20% capacity at commercial frequency where reactor 2 and reactor 2 are added
It consisted of the following. By controlling the firing phase angle of the thyristor 4 in this reactive power adjusting device, it was possible to control from leading reactive power to delayed reactive power. FIG. 2 shows this state and shows that the reactive power can be controlled from the advanced reactive power to the delayed reactive power with respect to the firing phase angle of the thyristor 4. FIG. 3 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. As shown in the figure, the current flowing through the thyristor increases as the delay reactive power increases. The thyristor has a high specific gravity in terms of configuring the reactive power adjusting device shown in FIG. 1, and the thyristor having a voltage suitable for a high voltage in which the reactive power adjusting device is generally used has few current capacity types.
As the current capacity increased, the price had increased significantly. Therefore, in order to control the delay reactive power to, for example, 100% with the reactive power adjusting device shown in FIG. 3 for industrial practical use, a thyristor capable of supplying a current larger than the current capacity shown in FIG. For example, the delay reactive power 50% shown in FIG.
A thyristor capable of supplying a current b capable of controlling the current is selected, the reactive power control range is advanced, and the reactive power control range is delayed from 100% to 50%. FIG. 4 shows the relationship of the harmonic current to the operating reactive power of the conventional reactive power adjusting device. As shown in FIG. 4, as the delayed reactive power increases, the harmonic current also 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 is narrowed and used. 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 price of connecting this device can be significantly higher.

[0003] These facts show that there is a limit to the usable range of the reactive power adjusting device shown in FIG.

[0004]

In the conventional reactive power adjusting device, as shown in FIGS. 3 and 4, a large amount of current flows through a thyristor operating at a point where the amount of delayed reactive power is large. As shown in FIG. 4, the control range of the amount of delayed reactive power is determined by both the harmonic current and the allowable current value of the thyristor when industrially practically used. The state is shown in each of FIGS. 3 and 4, and the control range of the delayed reactive power is about 50% of the control range of the advanced reactive power.

The present invention has been made to solve the above-mentioned problems of the conventional reactive power adjusting device.
Reduces the lag reactive power control range from the leading reactive power control range to a level at which it is not necessary to install harmonic filters in parallel with the harmonic current, and the current capacity of the thyristor is the same as the industrially practical capacity It is intended to be able to control to the level and to expand the use of the reactive power adjusting device.

[0006]

A reactive power adjusting device according to the present invention connects a reactor 1, a reactor 2 and a capacitor in series to suppress a harmonic current flowing out of the reactive power adjusting device, and connects the reactor 1 and the reactor. In a reactive power adjusting apparatus in which a thyristor connected in anti-parallel is connected to the connection point of No. 2, the capacity at the commercial frequency obtained by adding the reactor 1 and the reactor 2 to the capacity of the capacitor is 30.
% To reduce the thyristor current and increase
The harmonic current is suppressed .

[0007]

The reactor 1, the reactor 2 and the capacitor are connected in series, the thyristor connected in anti-parallel to the connection point of the reactor 1 and the reactor 2 is connected, and the capacity of the reactor 1 and the reactor 2 added to the capacitor capacity. Is set to 30% or more, the current flowing through the reactor is controlled by the thyristor, and the amount of reactive power is continuously variably controlled.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As in the prior art, the reactor 1 and the reactor 2
And a capacitor are connected in series, and a thyristor connected in anti-parallel to the connection point between the reactor 1 and the reactor 2 is connected. According to the present invention, the reactor 1 and the reactor 2 indicated by the commercial frequency are added to the capacitor capacity. The capacity is 30%.

FIG. 5 is a diagram for explaining an embodiment of the present invention. In Fig. 5, the horizontal axis is the capacitance ratio at commercial frequency obtained by adding reactor 1 and reactor 2 to the capacitance of the capacitor.

[0010]

(Equation 1)

The vertical axis indicates the thyristor current. The data shown in this figure is an example of data at the time of operation with 100% delayed reactive power and 50% delayed reactive power with respect to the capacity at the commercial frequency obtained by adding the reactor 1 and the reactor 2 to the capacitor capacity. In the figure, an intersection A of a straight line a parallel to the horizontal axis and a curve at the time of 100% operation of delayed reactive power indicates a thyristor current value at the time of 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 indicates the thyristor current during the operation of the conventional reactive power adjusting device. C indicates a thyristor current during 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 with 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. 6 shows a comparison of harmonic currents with respect to the operating reactive power of the conventional reactive power adjusting device and the reactive power adjusting device of the present invention. In this figure, the curve a indicates the harmonic current of the conventional reactive power adjustment value, and the curve b indicates the 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 system can be installed in a power system without installing a harmonic filter in parallel with the reactive power adjusting device according to the present invention, and the practical value has been greatly improved.

FIG. 7 is a diagram comparing the effective capacity of the reactor 2 which is a component of the conventional reactive power adjusting device and the reactive power adjusting device according to the present invention. The effective capacity is the capacity of the current flowing through the reactor 2 including the current of the commercial frequency component as well as many harmonic currents flowing therethrough. In the figure, a curve a indicates a conventional curve, and b indicates an effective capacity of the reactor 2 of the reactive power adjusting device of the present invention. This figure shows that the effective capacity of the reactor 2 according to the present invention is significantly reduced as compared with the conventional device. This leads to reduction in noise due to harmonic current included in the current flowing through the reactor 2 while exhibiting 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 and the harmonic current as compared with the conventional reactive power adjusting device at the same current capacity of the thyristor used in the present device. In addition, the effective capacity of the reactor 2 used in the present apparatus is also reduced, and the reactor 2 can be reduced in size, weight, and price, and the noise can be reduced.

[0015]

As described above, according to the present invention, the reactor 1,
A reactor is connected in series with a capacitor, and a thyristor connected in anti-parallel to a connection point between the reactor 1 and the reactor 2 is provided. The sum of the capacity of the reactor 1 and the reactor 2 indicated by the commercial frequency is 30 times the capacity of the capacitor.
% Or more, the thyristor has the same current capacity, the delayed reactive power control range is greatly expanded and the harmonic current is greatly reduced compared to the conventional reactive power adjustment device, and furthermore, it is used in this device. The effective capacity of the reactor 2 is reduced, and the reactor 2 can be reduced in size, weight, and price, and noise can be reduced.

[Brief description of the drawings]

FIG. 1 is a single-line diagram of a reactive power adjusting device.

FIG. 2 is a diagram showing control reactive power with respect to a thyristor firing angle of the reactive power adjusting device.

FIG. 3 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. 4 is a diagram showing a relationship between an operation reactive power and a harmonic current of the conventional reactive power adjusting device.

FIG. 5 is a diagram illustrating a comparison between currents flowing through thyristors of a conventional reactive power adjusting device and a reactive power adjusting device according to the present invention.

FIG. 6 is an explanatory diagram of the device of the present invention in which harmonic currents with respect to the reactive power of the reactive power adjusting device of the present invention are compared with those of the conventional reactive power adjusting device.

FIG. 7 is an explanatory diagram of the device of the present invention comparing the effective capacity of the reactor 2 with respect to the reactive power of the conventional reactive power adjusting device and the reactive power adjusting device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reactor 1 2 Reactor 2 3 Capacitor 4 Antiparallel connection thyristor

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Makoto Kusano 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-3-222015 (JP, A) JP-A-3-113521 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G05F 1/70 H02J 3 / 18

Claims (1)

(57) [Claims] A thyristor is connected in series with a reactor 1, a reactor 2 and a capacitor, and a thyristor connected in anti-parallel to a connection point between the reactor 1 and the reactor 2 is provided. reclaim by second adding the capacity is 30% or more
A reactive power adjustment device characterized by reducing star current and suppressing harmonic current .