JPH0629884A - High frequency power injecting device - Google Patents

Abstract

PURPOSE:To provide the subject device with a compact and inexpensive configuration by reducing the output capacity of a high frequency oscillator. CONSTITUTION:The device is provided with a reactor 7 inserted in series into an electric power system, a secondary induction winding wire 8 added to this reactor 7, and a high frequency oscillator 6 for supplying an oscillation output to the secondary induction winding wire 8 through a blocking capacitor 9 for obstructing a system voltage. Even if an excitation impedance of the reactor 7 is small, and a secondary circuit becomes an open state against a commercial frequency of the system by the capacitor 9, an induced voltage of the commercial frequency between its terminals does not become excessive, and also, it is obstructed by the capacitor 9 that a current of a commercial frequency flows into the oscillator 6, therefore, a necessary output capacity of the oscillator 6 is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency power injection device for injecting high frequency power into a power system.

[0002]

2. Description of the Related Art Conventionally, when injecting high frequency power into a power system as a power line carrier control signal or a waveform distortion correction signal, a parallel injection type high frequency power injection device shown in FIG. 3 or a serial injection type high frequency shown in FIG. A power injection device is used.

In these drawings, 1 is a commercial power source, 2
Is an equivalent inductance indicating the impedance of the power supply 1,
3 and 4 are equivalent inductances and equivalent capacitors showing line impedance of the power system, 5 is a system load, and 6 is a high frequency oscillator for high frequency power injection.
Is connected in parallel to the power system and is provided in parallel to the power system. In FIG. 4, the power source 1 is connected in series and inserted in the power system in series. Then, in the case of FIG. 3, the high frequency power of the oscillator 6 is injected in parallel to the power system, and in the case of FIG. 4, the high frequency power of the oscillator 6 is injected in series to the power system.

[0004]

In the conventional devices shown in FIGS. 3 and 4, the output of the oscillator 6 is injected into the power system as it is or through a transformer, so that the output capacity (electric power) of the oscillator 6 is increased. However, there is a problem that a large and expensive structure is required.

That is, in FIGS. 3 and 4, if the rated system voltage and system current (load current) are V _S and I _S, and the output voltage and injection current of the oscillator 6 are V _H and I _H , the output Electric power is V _S · I _H (parallel injection method in FIG. 3), I _S ·
V _H (series injection method of FIG. 4).

If the power source impedance of the power system is 5% based on the rated capacity and the output frequency of the oscillator 6 is 1 KHz, which is 20 times the commercial power source 1, then 5% of the system voltage.
In order to generate an appropriate high frequency voltage of 3 in the system in the case of FIG. 3, 5% of the system current I _S is required as the injection current I _H as shown in the following equation (1). In this case, 5% of the system voltage V _S is required as the output voltage V _H.

[0007]

[Equation 1] 0.05 · (V _S / I _S ) · 20 · I _H = 0.05 · V _S ∴I _H = 0.05 · I _S

Therefore, in any of the devices shown in FIGS. 3 and 4, the oscillator 6 is used as 5% (V _S
A large and expensive oscillator with a large output capacity of I _S · 0.05) is required. It is an object of the present invention to provide a high frequency power injection device capable of injecting appropriate high frequency power by significantly reducing the output capacitance of the oscillator as compared with the conventional one.

[0009]

In order to achieve the above object, in a high frequency power injection apparatus of the present invention, a reactor inserted in series in a power system and a secondary induction winding added to this reactor. , A high-frequency oscillator that supplies the oscillation output to the secondary induction winding through a blocking capacitor for blocking the system voltage.

[0010]

In the case of the high frequency power injection device of the present invention constructed as described above, the secondary induction winding is added to the reactor inserted in series in the power system, and the high frequency oscillator of the high frequency oscillator via the blocking capacitor is added to this winding. A high frequency oscillation output is supplied.

At this time, since the reactor has a small exciting impedance unlike a transformer, a circuit configuration equivalent to opening the secondary circuit of the reactor with respect to the commercial frequency of the system by a blocking capacitor is provided. Since the induced voltage at the commercial frequency does not become excessive and the current at the commercial frequency does not flow into the oscillator due to the blocking capacitor, the output capacity of the oscillator required to generate an appropriate high frequency voltage in the power system is higher than that of the conventional device. It becomes extremely small.

[0012]

EXAMPLE One example will be described with reference to FIGS. In FIG. 1, the same reference numerals as those in FIGS. 3 and 4 indicate the same or corresponding ones, 7 is a reactor having a core structure and is inserted in series in the power system, and 8 is a secondary induction winding added to the reactor 7. Yes, the output of the oscillator 6 is supplied. Reference numeral 9 denotes a blocking capacitor provided between the secondary induction winding 8 and the oscillator 6 for blocking a system voltage at a commercial frequency (low frequency).

The output of the oscillator 6 is the capacitor 9,
It is injected in series into the power system via the secondary induction winding 8 and the reactor 7. At this time, the oscillator 6 is electrically insulated from the power system by the secondary induction winding 8.

Since the secondary induction winding 8 magnetically and tightly coupled to the reactor 7 is provided, the leakage impedance between the windings 7 and 8 is small, and the load impedance seen from the oscillator 6 is the secondary induction winding 8. Assuming that the number of turns is the same as the number of turns of the reactor 7, the impedance of the reactor 7 is almost obtained. Further, the commercial frequency voltage induced in the secondary induction winding 8 is blocked by the capacitor 9 and the oscillator 6
Is prevented from being applied.

To simplify the explanation, assuming that the turns ratio of the reactor 7 and the secondary induction winding 8 is 1: 1 and considered equivalently, the main part of FIG. 1 is the equivalent circuit of FIG. Can be shown. In this FIG. 2, assuming that the commercial frequency series impedance of the reactor 7 is X, and the rated system voltage and system current (load current) are V _S and I _S , the power capacity P _L of the reactor 7 is expressed by the following formula 2. Indicated by.

[0016]

[Formula 2] P _L = (I _S ) ² · X

Further, X = K _L · (V _S / I _S ) (K _L is a coefficient), and the rated load capacity (= V _S · I _S ) is Pl.
Then, the following equation 3 is obtained from the equation 2.

[0018]

[Formula 3] P _L = (I _S ) ² · K _L · (V _S / I _S ) = K _L · V _S · I _S = K _L · Pl

On the other hand, the output voltage V is applied across the reactor 7.
Output capacity P _H of the oscillator 6 need to apply the _H, the output frequency of the oscillator 6 is sufficiently higher than the commercial frequency, it is possible to ignore the impedance of the capacitor 9, the number of the next 4
It is shown by the formula.

[0020]

[Formula 4] P _H = (V _H ) ² / (Kf · X)

Kf represents the frequency multiple of the output frequency (high frequency) of the oscillator 6 with respect to the commercial frequency. When an appropriate high frequency voltage of 5% of the system voltage V _S is generated in the power system, the applied voltage V _H across the reactor 7 is applied.
To 0.05 · V _S and indicated by the number 5 Formula of the required output capacity P _H Hatsugi oscillator 6.

[0022]

P _H = {(0.05) ² / Kf} · [(V _S ) ² / {K _L · (V _S / I _S )}] = {(0.05) ² / (Kf · K _L)} · Pl

Therefore, as is clear from the equations (3) and (5), in the case of the series insertion using the reactor 7, the coefficient K _L is the output capacitance P _{L of the} reactor 7 and the output capacitance P _H of the oscillator 6. It becomes a factor of trade-off. Then, in order to make the output capacitance P _H of the oscillator 6 as small as possible, P _H = 0.0
When setting 3 · P _L , P _H and P _L have the sizes described below with respect to P 1, respectively.

That is, the equations of the equations 3 and 5 and P _H = 0.0
The following equation 6 is obtained from the relationship of 3 · P _L.

[0025]

[Equation 6] 0.03 · K _L · Pl = {(0.05) ² / (Kf · K _L )} · Pl

Further, the following equation 7 is obtained from the equation 6.

[0027]

[Formula 7] K _L ² = (0.05) ² /(0.03·Kf) ∴K _L ≈0.29 · (1 / √Kf)

The equation (7) shows that the coefficient K _L is determined depending on the output frequency of the oscillator 6. When the output frequency of the oscillator 6 is 1 KHz, which is 20 times the commercial frequency, Kf = 20 and K _L ≈0.06.

Furthermore, substituting these values into the numerical formula 5, the values shown in the numerical formula 8 P _H Hatsugi.

[0030]

[Formula 8] P _H = {(0.05) ² /(20·0.06)}·Pl ≈ 2.1 · 10 ⁻³ · Pl

Further, P _L becomes a value shown in the following equation 9 by the equation 3

[0032]

[Equation 9] P _L = 0.06 · Pl

Therefore, the output capacitance P _{L of the} reactor 7
When the 0.06 · Pl and that by the output capacitance P _H of the oscillator 6 in a very small volume of 2.1 · 10 ^-3 · Pl to generate the 5% of the high-frequency voltage of the system voltage V _S to the power system it can. In the case of the conventional device, the output capacitance P _H of the oscillator 6 is set to 0.05.
Requires a capacity of Pl.

The output capacitances P _H and P _L can be set variously, but from the practical point of view, considering the size of the reactor 7 and the like, the impedance X thereof is in the range of 1 to several% of the rated load impedance. It is preferable to set to.

In the above embodiment, the equivalent circuit for directly supplying the output of the oscillator 6 to the reactor 7 has been described. However, in order to insulate the oscillator 6 from the power system, the output of the oscillator 6 is secondary through a transformer. It may be supplied to the induction winding 8.

[0036]

Since the present invention is configured as described above, it has the following effects. A reactor 7 is inserted in series in the power system, a secondary induction winding 8 is added to this reactor 7, and the oscillation output of the high-frequency oscillator 6 is supplied to the reactor 7 via the blocking capacitor 9 and the secondary induction winding 8. However, since high-frequency power is injected into the power system, the exciting impedance of the reactor 7 is small, and even if the secondary circuit is opened to the commercial frequency by the capacitor 9, the induced voltage at the commercial frequency between the terminals does not become excessive. Moreover, the capacitor 9 prevents the commercial frequency current from flowing into the oscillator 6, and the output capacity of the oscillator 6 required for generating an appropriate high frequency voltage in the power system becomes much smaller than that of the conventional device. Since 6 is small and inexpensive, the device can be downsized and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a connection diagram of an embodiment of a high frequency power injection device of the present invention.

FIG. 2 is an equivalent circuit diagram of a main part of FIG.

FIG. 3 is a connection diagram of an example of a conventional device.

FIG. 4 is a connection diagram of another example of the conventional device.

[Explanation of symbols]

 6 High-frequency oscillator 7 Reactor 8 Secondary induction winding 9 Blocking capacitor

Claims (1)

[Claims] 1. A reactor inserted in series in a power system, a secondary induction winding added to the reactor, and an oscillation output supplied to the secondary induction winding through a blocking capacitor for blocking the system voltage. A high frequency power injection device comprising a high frequency oscillator.