JPH06153400A - Efficiency improving unit in power use - Google Patents

Abstract

PURPOSE:To provide an efficiency improving unit in power use in which improvement of power factor, removal of high frequency wave, and suppression of flickering can be processed concurrently. CONSTITUTION:Series circuits, each comprising a set of capacitor 1, a reactor 2, reverse connected diodes 5, and a thyristor 6, are connected in delta to constitute units IA, IIA for load A and units IB, IIB,... for load B. Since the load A is an induction machine, e.g. a motor, which may produce fifth higher harmonic, a 6% reactor 2 is employed. Since the load B is a pulse control machine employing semiconductor, e.g. an inverter, having high higher harmonic ratio other than fifth higher harmonic, a 13% reactor is employed. When both fifth higher harmonic and other higher harmonics are contained, 6% and 13% reactors are connected in parallel. This constitution removes higher harmonics positively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power consumption efficiency improving device, and more particularly to a power consumption efficiency improving device capable of simultaneously processing power factor correction, harmonic elimination and flicker elimination.

[0002]

2. Description of the Related Art The use efficiency of electric power depends on the power factor and the presence or absence of harmonics. The power factor is improved and harmonics are removed by using a filter in which a capacitor and a reactor are inserted between lines or between a line and a neutral point.

FIG. 6 shows a single wire (one of three phases) connection diagram of a low pressure filter which has been conventionally used.
6% reactor L ₅ for removing the 5th harmonic, 8% reactor L ₇ for removing the 7th harmonic, 13 for removing the 11th harmonic
% Reactor L ₁₁ and corresponding capacitor C
₅ , C ₇ and C ₁₁ are connected in parallel at the same time.

FIG. 7 shows a pair of capacitors and a reactor (for example, capacitor C ₅ and reactor L of the device shown in FIG. 6).
It is a detailed view about ₇ ). It is composed of Δ-connected capacitors 1a ′, 1b ′, 1c ′ and reactors 2a ′, 2b ′, 2c ′ inserted between the vertices of the Δ-connection and the line, and a load is turned on by a switch 4 ′. At the same time, the switch 4 on the device side is turned on. This not only improves the power factor, but by appropriately selecting the size of the reactor, harmonics are also removed to some extent, and it is possible to reduce the waveform distortion and improve the power use efficiency.

Since this device is intended to improve the delay of the current generated due to the induction of the load or to remove the higher harmonics, the switch 4 and the switch 4'inject the load and the line simultaneously. The load is released and the line is released at the same time.

By the way, capacitors 1a 'and 1
When b'and 1c 'are inserted, an impulsive wave may be generated if the voltage across the capacitor and the line voltage do not match at the time of closing, and the load or the capacitor may be destroyed or deteriorated. Therefore, as shown in FIG.
(1b, 1c), a diode 5a (5b, 5c) and a thyristor 6a (6b, 6c) connected in reverse polarity to the diode 5a (5b, 5c) are connected in series to form a Δ connection. There is.

FIG. 9 is a timing chart showing waveforms of various parts when the switching control circuit 200 controls the filter having the above-described structure shown in FIG. When the load is turned on at time T ₀ and the thyristors 6a, 6b and 6c are turned on, the capacitors 1a, 1b and 1c are connected in parallel between the phases, and the power factor adjusting function works. The timing at which the thyristors 6a, 6b and 6c are brought into conduction is important here.

First, the capacitors 1a, 1b and 1c are connected to the diode 5 while the thyristors 6a, 6b and 6c are not conducting as shown in FIG.
The interphase voltage V shown in (a) of FIG. 9 via a, 5b, and 5c.
It is charged to a voltage at or near the maximum value V _{D of M.}
Therefore, if the interphase voltage is also near the maximum value V _D (the maximum is the best) when the thyristors 6a, 6b, and 6c are conducting, the power factor adjusting function can be started without the occurrence of an impulse wave, and the time Is T ₁ in FIG.

Therefore, at time T ₁ , the thyristors 6a, 6b,
6C to conduct the switching control circuit 200 from the thyristor 6
A gate voltage V _G is applied to the gates of a, 6b and 6c as shown in FIG. This voltage waveform is a DC voltage that rises at the time T ₁ and falls at T ₂ when the load is released.

As described above, the thyristors 6a of each phase are
When 6b and 6c are turned on, the line voltage changes to the capacitor voltage Vc.
Thyristors 6a, 6 for the lower half cycle
b, 6c, and in the half cycle when the line voltage becomes higher than the capacitor voltage, the diodes 5a, 5b, 5c become conductive, and eventually the diodes 5a, 5b, 5c and the thyristor 6 are turned on.
a, 6b and 6c are alternately conducted every half cycle to form a capacitor current Ic as shown in FIGS.
Power factor adjustment and harmonic removal will be performed.

Next, time T₂The load is released and
Sometimes thyristor gate voltage V_GIf you turn off
Since the diodes 5a, 5b, 5c are conducting, time T
₃Up to, the capacitors Ta, Tb, Tc are charged,
The maximum line voltage after that is V _GTime T₃At Siri
No current flows through the capacitors 6a, 6b, 6c
1a, 1b, and 1c are time points T when the capacitor current Ic is zero.₃
The capacitors 1a, 1b, 1c are separated from each phase by
Line voltage V as in the initial state_MVoltage near the maximum value of
And then the thyristors 6a, 6b, 6c become conductive again.
This state will be maintained until

Even when the load is released at time T ₄ and the gate voltage V _G is made zero at the same time, for example, until time T ₅ , the thyristors 6a, 6b, 6c remain in the conductive state, and from time T ₅ to. Diodes 5a, 5 up to T ₃
b, a capacitor 1a at the end time T ₃ because 5c is conducting, 1b, 1c will be cut is made from the line.

The waveform shaping reactor 2 shown in FIG.
a, 2b, and 2c are series reactors 2a ′ in FIG.
It is used instead of 2b 'and 2c'. Further, in order to remove the flicker generated from the spot welder or the like, a circuit as shown in FIG. 10 is used. That is, the capacitor 1d and the reactor 2d are connected in parallel to the line, and the switching element 7 is connected to the reactor 2d, and the switching element 7 is normally off.
In this state, when the load becomes large, the flicker that occurs when the load is turned on is short-circuited via the reactor 2d and the voltage is maintained by the capacitor 1d.

[0014]

The voltage fluctuation rate with respect to the supply voltage is 5% or less in total, the fifth harmonic is 3% or less, the second
It is specified that 3 harmonics or less is 1% or less. However,
Conventional power factor improvement using only capacitors (harmonic removal)
According to the circuit, as shown in Table 1, the voltage distortion rate was as high as 20% or more, which was not a very effective means.

Further, since it is considered that the odd harmonics among the harmonics have a great influence on the use efficiency, only consideration is given to removing the odd harmonics. That is,
As shown in FIG. 6, in the method using a capacitor and a reactor, for example, a combination of a capacitor C ₅ for removing the fifth harmonic and a 6% reactor L ₅ and a capacitor C ₇ for removing the seventh harmonic are used. A combination of an 8% reactor L ₇ and a capacitor C ₁₁ for removing the 11th harmonic and a 13% reactor L ₁₁ were connected in parallel, and a capacitor and a reactor with a fixed capacity were always connected for all loads. .

However, it is not only the odd harmonics that affect the waveform distortion, but also the even harmonics (see the second harmonic in Table 2) of the magnitude as shown in Table 2. If the waveform distortion occurs, the use efficiency deteriorates. Conventionally, there were few even-order harmonics, so there was a tendency to focus on removing odd-order harmonics as described above, but in recent years pulse control using semiconductor devices such as inverters has been performed. When the number of devices increases, when using a device that is inclined to remove odd harmonics as described above, even if the power factor adjustment is good, the harmonics cannot be completely removed and the voltage waveform is distorted. There is a tendency for the efficiency to deteriorate.

Further, the magnitude of the higher harmonics and the phase shift increase with the magnitude of the load. However, if a reactor or capacitor with a fixed value for the load is used as described above, even if it is balanced under the rated current and rated voltage, it will break the balance under a load smaller than the rating,
You will not be able to achieve your goal.

Further, the flicker removing device shown in FIG. 10 is a device different from the power factor improving or harmonic removing device, and sufficient equipment for that purpose is required. The present invention has been proposed in view of the above-mentioned conventional circumstances, and is capable of improving power factor, removing odd-order and even-order harmonics, and further eliminating flicker appropriately, and using electric power almost completely by one device. An object is to provide an efficiency improving device.

[0019]

The present invention employs the following means in order to achieve the above object. That is, in the device for improving the power use efficiency by inserting the capacitor and the reactor between the lines or between the transmission line and the neutral point, as shown in FIG. The reactor used is 6% of the line rated capacity, and the reactor of 13% of the line rated capacity is used to remove other harmonics.

That is, the harmonics emitted by a device used as a load differ depending on the type of the device. Therefore, depending on the order of the harmonics emitted by the device, a 6% reactor, 1
Try to use 3% reactor or both at the same time.

Furthermore, the harmonics can be removed more effectively by changing the capacitor capacity and the reactor capacity according to the size of the load.

[0022]

As shown in Table 2, if a reactor of about 6% is used, the voltage of the fifth harmonic can be suppressed to 3% or less of the peak value of the total voltage. Further, as shown in Table 3, if a reactor of about 13% is used, harmonics other than the fifth harmonic can be suppressed to an extremely low level.

The fifth harmonic is generated from a highly inductive device such as a motor. Therefore, a device using a 6% reactor is applied to the motor and the like. In addition, even-order harmonics are generated in a device, such as an inverter, in which the supplied power is once rectified, smoothed by a capacitor, and used for pulse control. Therefore, a device using a 13% reactor is applied to this kind of equipment.

Further, since there are devices that generate the fifth harmonic and other harmonics, it is possible to use 6
Equipment with both% and 13% reactors is applied.

[0025]

FIG. 1 is a principle view showing an embodiment of the present invention. Units I _A , II _A, ... (Units I _B , II _B, ... For load B) for each load A are respectively capacitors 1
(1a, 1b, 1c), reactor 2 (2a, 2b, 2
c), the diodes 5 (5a, 5b,
5c) is a single wire connection diagram in which a set of series circuits is Δ-connected by a thyristor 6 (6a, 6b, 6c).

The load A is an inductive device such as a motor and is likely to generate fifth harmonic waves. Therefore, a 6% reactor is used as the reactor 2 (2a, 2b, 2c) for this type of device.

The load B is a device such as an inverter that performs pulse control using a semiconductor, and the ratio of harmonics other than the fifth harmonic is high. In this case, a 13% reactor is used as the reactor.

Further, when both the fifth harmonic and the other harmonics are included, the reactors of 6% and 13% are used in parallel. In the present invention, the value of the reactor is determined according to the equipment used as described above, and the capacity of the capacitor that operates depending on the load of the equipment used is changed.

That is, as shown in FIG. 2, the current value (current-corresponding voltage) detected by the current transformer 30A corresponding to the load A is rectified and A / D converted by the detection unit 11a of the load recognition device 10A, and then the comparator 12a. Entered in. This comparator 12a is a current transformer 30A
When the current is detected by (when the current is larger than zero), the control unit 200a of the opening / closing control device 20A is operated to cause the thyristor 6 (6
a, 6b, 6c) are turned on.

The current value detected by the current transformer 30A is A / D converted by the detector 11a and input to the comparator 12b.
2b is when the current exceeds a predetermined value (for example, 25
When it becomes larger than the value equivalent to kvA), the control unit 200b of the load recognition means is operated, and the thyristor 6 (6a, 6b, 6c) of the unit II is operated.

As shown in FIG. 3, the opening / closing control device 20A includes a control unit 200 corresponding to each unit I _A , II _A.
a, 200b ... Here, in FIG. 3, only the control unit corresponding to one unit is shown.

The voltage signal Sv inputted from the terminal P ₁ is inputted to the phase voltage maximum voltage detection unit 71, wherein the output up to check detection pulse P ₀ when the interphase voltage becomes maximum, the pulse P ₀ Is input to the AND gate 74.
The output of the comparator 12a of the unit I is input to the load closing detector 72. This load input detector 7
Reference numeral 2 outputs a closing pulse Pi having a length of "1" for almost one cycle when the output of the comparator 12a becomes "1", that is, when a load is supplied. The closing pulse Pi is input to the AND gate 74, and the output of the AND gate 74 is input to the set terminal Ps of the set / reset circuit 76.

The output of the comparator 12a is also input to the load release detector 73. The load opening detection unit 73 outputs an opening pulse Pt when the load is released, the reset terminal Pr of the pulse P _t is the set-reset circuit 76
Has been entered in.

When the switching control device 20A is configured in this way, the set / reset circuit 76 is set by the closing pulse Pi when the interphase voltage is maximum after the load is turned on.
Further, when the load is released, the set reset circuit 76 is reset by the release pulse Pt, and the gate voltage V _G as shown in FIG. 9 can be obtained from the terminal P ₃ .

When the current exceeds a certain value, then Unit II
_{The A} comparator 12b is activated and the corresponding control unit 7a is activated. The above configuration and operation are exactly the same for the switching control device 20B for the load B.

By increasing the capacity according to the load in this way, it is possible to remove harmonics according to the size of the load. Table 1 shows the ratio of the magnitude (voltage) of the harmonics of each order (when the first order is 100%) and the phase when the harmonics are removed and the power factor is improved only by the capacitor. is there. Table 2 is 6% in Figure 1 (Figure 2)
Table 3 shows the proportion and phase of the above harmonics when the reactor was used and when a 13% reactor was used.

According to Table 2, 5% by 6% reactor
The harmonics are suppressed to 3% or less, but the other harmonics are not suppressed to the target value or less. Therefore, it can be seen that there is voltage fluctuation as is clear from FIG. 4A, and the power factor is not sufficiently improved from FIG. 4B. Further, according to FIG. 5 (a) showing Table 3 and the waveforms of Table 3 in the drawing, 13
It can be understood that the% reactor suppresses the harmonics other than the fifth harmonic to a significantly small value, and as is clear from FIG. 5B, the power factor is considerably improved.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

[Table 3]

[0041]

As described above, according to the present invention, since the reactor is changed according to the kind of harmonic generated by the device serving as a load, the harmonic can be reliably removed. Further, since the capacitor capacity and the size of the reactor are changed according to the size of the load, it is possible to operate the capacitor and the reactor having the size corresponding to the change of the load, and the above effect is further effective.

[Brief description of drawings]

FIG. 1 is a principle view of the present invention.

FIG. 2 is a circuit diagram of an embodiment of the present invention.

FIG. 3 is a circuit diagram of an embodiment of an opening / closing control device.

FIG. 4 is a waveform diagram showing the contents of Table 2 as a drawing.

FIG. 5 is a waveform diagram showing the contents of Table 3 as a drawing.

FIG. 6 is a circuit diagram showing a conventional example.

FIG. 7 is a more detailed circuit diagram of a conventional example.

FIG. 8 is another circuit diagram of a conventional example.

FIG. 9 is a timing chart of a conventional example.

FIG. 10: Conventional flicker removal circuit

Claims (3)

[Claims] 1. In a device for improving power use efficiency by inserting a capacitor and a reactor between lines or between a transmission line and a neutral point, a line rated capacity of A power usage efficiency improving device characterized by using a reactor of 6% and using a reactor of 13% of the rated line capacity for removing other harmonics. 2. The power usage efficiency improving device according to claim 1, wherein a 6% reactor, a 13% reactor, or both of them are used properly according to the order of the harmonics output from the device used as a load. 3. The power usage efficiency improving device according to claim 1, wherein the capacitor capacity and the reactor capacity are changed according to the size of the load.