JPH06269126A - Voltage regulator - Google Patents

Abstract

PURPOSE:To suppress a voltage fluctuation by a method wherein the width of the pulse width of a pulse-shaped AC voltage is changed in such a way that the magnitude of an AC voltage received by a load becomes a prescribed magnitude. CONSTITUTION:When a voltage applied to a load is changed, a control part 20 detects the fluctuation of the voltage from the detected result of a detection part 10. Then, the control part 20 controls a switch part 40 in such a way that the voltage received by the load becomes a prescribed voltage, and it changes the pulse width of a pulse-shaped voltage generated by the switch part 40. A filter part 50 takes out a voltage whose frequency is the same as that of the voltage applied to the load, and a voltage coupling part 60 applies the voltage to the voltage supplied to the load. Thereby, a voltage fluctuation is suppressed, and it is possible to prevent the influnce of a resistance up to the load.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage regulator which regulates fluctuations in voltage supplied to a load.

[0002]

2. Description of the Related Art A voltage regulator is inserted into, for example, a high-voltage power distribution line to regulate fluctuations in an AC voltage supplied to a load. As this voltage adjusting device, for example, one iron core / one winding type as shown in FIG. 15 (a), two iron core / three winding type as shown in FIG. 15 (b), or two iron cores as shown in FIG. 15 (c). Four
There are winding types.

In FIG. 15A, a winding 301 is used, and taps 301a to 301d of the winding 301 are switched to adjust the voltage. In FIG. 15B, the winding 30
2, 303 using the taps 302a to 30 of the winding 302
2e is switched, and the voltage obtained from this is added to the voltage supplied to the load by the winding 303. In addition, FIG.
Similarly in (c), the windings 304 and 305 are used to switch the taps 304a to 304e of the winding 304, and the voltage obtained from this is changed to the voltage supplied to the load.
I am adding in. These devices are called a series compensation system and are used by being inserted in series in a high voltage power distribution line. Then, the voltage variation is adjusted by switching the taps in accordance with the voltage variation.

There is also a voltage compensation device called a parallel compensation system. In this method, for example, a reactive power supply source is installed on a high voltage distribution line. And this device
The change in the reactive power, which is one of the causes of the voltage change, is adjusted to compensate for the voltage.

Recently, as shown in FIG. 16, a voltage regulator using thyristors 401 and 402, a reactor 403 and a capacitor 404 has been put into practical use. This device inserts the reactor 404 in parallel by turning on and off the thyristors 401 and 402. This device
Along with high-speed control by phase control using the thyristors 401 and 402, control of whether or not the reactor 403 is added to the high-voltage distribution line is continuously performed.

The voltage regulators regulate the voltage supplied to the load.

[0007]

By the way, in the above-mentioned series type voltage regulator, the taps are switched stepwise during voltage regulation. However, in this device, the taps are switched mechanically, so the control is slow and continuous adjustment according to the voltage change cannot be performed.

On the other hand, in the parallel type voltage adjusting device, for example, the device shown in FIG. 16, the voltage for adding the reactor 403 is generated by turning on and off the thyristors 401 and 402, as shown in FIG. That is, the voltage is applied to the reactor 403 for the time γ, but the time δ is required before the voltage is applied. Therefore, there is a time delay in the phase control, and
Since such a waveform is added to the reactor 403, the amount of harmonic current generated increases. In addition, low-order harmonic currents that are difficult to remove with a filter are dominant. Further, this device adjusts the reactive current in principle, and the voltage adjustment effect is affected by the resistance of the distribution line up to the load. That is, the effect on the load side is reduced by the amount of the voltage drop due to this resistance. Further, this device requires the reactor 403 and the capacitor 404 having a large capacity, and thus becomes heavy and cannot be installed in the high-voltage power distribution line.

The object of the present invention is to eliminate the above drawbacks, and to adjust the voltage change at high speed and continuously according to the change of the voltage applied to the load, and to prevent the influence of the resistance to the load. To provide an adjusting device.

[0010]

In order to achieve the object, the present invention is a voltage regulator which is used by being inserted between a power supply side and a load and which regulates an AC voltage supplied to the load. Detecting means for detecting an alternating voltage and an alternating current supplied to the load, inducing means for inducing an alternating voltage almost proportional to the alternating voltage supplied to the load, and induction by repeating a conducting state and a non-conducting state. Switching means for converting the AC voltage from the means to pulsed AC voltage, filter means for extracting the AC voltage having the same frequency as the AC voltage supplied to the load from the pulsed AC voltage, and the AC supplied to the load The magnitude of the AC voltage received by the load is calculated from the coupling means for applying the AC voltage extracted by the filter means to the voltage, and the AC voltage and AC current detected by the detection means, and the calculated AC voltage is calculated. And the magnitude of the voltage controls the switching means to a predetermined size, and a control means for changing the width of the pulse width of the pulsed AC voltage.

[0011]

With this configuration, when the voltage applied to the load changes, the control means detects this fluctuation based on the detection result of the detection means. Then, the control means controls the switch means so that the voltage received by the load becomes a voltage of a predetermined magnitude, and changes the pulse width of the pulsed voltage generated by the switch means. From the pulsed voltage, the filter means extracts a voltage having the same frequency as the voltage applied to the load, and the coupling means applies this voltage to the voltage supplied to the load. As a result, voltage fluctuations are suppressed.

[0012]

Embodiments of the present invention will now be described with reference to the drawings.

[First Embodiment] FIG. 1 shows a first embodiment of the present invention.
It is a block diagram showing. In this voltage regulator, for example, as shown in FIG. 2, the substation 100 has a high-voltage distribution line 101.
When the power is transmitted to the loads 102 to 105 via the, the high voltage power distribution line 101 is inserted into the device installation point 106 and used. Then, the control target point 107 on the load side is set to a voltage of a predetermined magnitude. That is, the voltage regulator regulates the input voltage V _S of the sine wave of the substation 100 side is applied between the input terminals 1 and 2 to the output voltage V _L of the predetermined size, the output terminal of the output voltage V _L Send from 3 and 4 to the load side.

This voltage adjusting device includes a detecting section 10 as detecting means, a control section 20 as controlling means, a voltage inducing section 30 as inducing means, a switch section 40 as switching means, and a filter means. Filter section 50
And a voltage coupling section 60 as coupling means.

The detection unit 10 includes an instrument transformer 11 which induces a voltage V ₁ proportional to the input voltage V _S and an instrument current transformer which induces a current I ₁ proportional to a load current I _L sent to a load. 12 and 12. The detection unit 10 uses these voltages V ₁
And the current I ₁ are sent to the control unit 20.

The voltage inducing section 30 comprises a transformer 31 for generating a voltage V ₂ proportional to the input voltage V _S , and a capacitor 32. The capacitor 32 is a circuit element that prevents the current flowing through the transformer 31 from being interrupted when the switch unit 40 is switched off.

The switch section 40 is a GTO (Gate Turn-Off) thyristor, a power transistor or the like which is turned on (conducting) and turned off (non-conducting) by the pulse signal A sent from the control section 20. Then, by this turning on and off, the switch unit 40 causes the voltage V as shown in FIG.
Generates ₃ . The distribution angle α of the voltage V ₃ is determined by the pulse signal A and changes from 0 to β with respect to the control cycle β (α ≦ β). That is, as the output voltage V _L changes,
When the input voltage V _S is lowered, as the flow angle α is large, the input voltage V _S is increased, as the flow angle α becomes smaller, the switch unit 40 is turned on by the control of the control unit 20, OFF To do.

The filter section 50 has an inductance 51.
And a resistor 5 connected in parallel with the inductance 51
2 and a capacitor 53 connected in series with the inductance 51. The filter unit 50 absorbs a high frequency component from the voltage V ₃ generated when the switch unit 40 is turned on and off, and extracts a sinusoidal fundamental wave voltage V ₄ , that is, a voltage having the same cycle as the input voltage V _S.

The voltage coupling unit 60 is a transformer for adding the voltage V ₄ extracted by the filter unit 50 to the input voltage V _S.

The control unit 20 is composed of a microprocessor or the like, and generates the pulse signal A based on the voltage V ₁ and the current I ₁ induced by the detection unit 10. Then, the pulse signal A turns the switch unit 40 on and off.

Here, the procedure for the control unit 20 to generate the pulse signal A will be described in detail with reference to the equivalent circuit of FIG.

[0022] jX _L of the equivalent circuit shown in FIG. 4 shows the impedance of the inductance 51, -jX _C indicates the impedance of the capacitor 53. Further, the value of the resistor 52 is large, so that it is omitted. In addition, j represents an imaginary unit (j ² = −1). Further, k is the switch unit 4
The distribution rate is 0. When the control period β is sufficiently small,

[Equation 1] It is represented by. At this time, the voltage generated in the capacitor 53
^* V ₄ is expressed by the following equation based on the equivalent circuit of FIG. The voltage V ₄ generated in the capacitor 53 is a vector quantity, here represented as a vector voltage V ₄ ^* V _4. Hereinafter, a vector is similarly expressed by using "*".

[0023]

[Equation 2] Here, the voltage ^* V ₂ is used as the reference vector, and the load current
^* I _L

[Equation 3] When expressed by, the fundamental wave voltage applied to the voltage coupling unit 60 is

[Equation 4] Becomes Since the fundamental wave voltage V ₄ is usually smaller than the voltage V ₂ , the real part of the equation (4) is mainly involved in voltage adjustment. That is, the substantial voltage adjustment amount in the equation (4) is
Approximately

[Equation 5] Becomes

Further, in equation (5),

[Equation 6] And

At a normal power peak, the load current I
_L becomes large and becomes a delay power factor (the imaginary part b _L is negative). In this case, it is necessary to raise the voltage of the control target point 107 (FIG. 2). (5) As is clear from the equation, the normal change in b _L at peak power, voltage,
It is automatically corrected by the load current I _L. Furthermore, by using the term of kV ₂ together in the equation (5), the control target point 10
The voltage of 7 (FIG. 2) can be effectively increased.

Further, during midnight, the real part a _L of the load current I _L is reduced, the imaginary part b _L positive. In this case, the voltage at the control target point 107 (FIG. 2) needs to be lowered. Therefore, at midnight, kV _{2 is set} to a sufficiently small value and V _q is set to a negative value.

In addition to the correction function based on the load current I _L , the control unit 20 further corrects by kV ₂ of equation (5) in order to set the control target point 107 (FIG. 2) to a voltage of a predetermined magnitude. do. For this correction, the control unit 20 determines the control target point 1 from the voltage V ₁ and the current I ₁ detected by the detection unit 10.
07 (FIG. 2) voltage is estimated, and based on this estimation,
The distribution rate k in the equation (1) is calculated, and the distribution angle α is determined from the distribution rate k.

The control unit 20 determines the distribution angle α by the control method shown in FIG. That is, the control unit 20
The voltage V ₁ and the current I _{1 at} the device installation point 106 are detected by the instrument transformer 11 and the instrument current transformer 12 of the detector 10 (step S1). Voltage V ₁ detected in step S1
And the current I ₁ from the control target point 107 (FIG. 2) voltage V _r
Is calculated (step S2). At this time, a voltage drop due to the high voltage distribution line 101 from the device installation point 106 to the control target point 107 is calculated by the current I ₁ , and the voltage V _r is calculated from this voltage drop and the voltage V ₁ .

The magnitude of the voltage at the control target point 107 (FIG. 2) is predetermined, and this voltage is the specified voltage. From the voltage V _{r of} the control target point 107 (FIG. 2) calculated in step S2 and the specified voltage, the control unit 20 calculates

[Equation 7] Is calculated (step S3). In Expression (7), ε is a dead band width designated in advance.

If the difference is smaller than the dead zone width ε in the calculation of step S3, the process returns to step S1. If the difference in step S3 is larger than the dead zone width ε, the control unit 20 calculates the distribution rate k from the equation (2) (step S3).
4) The distribution angle α is calculated from the calculated distribution rate k and the equation (1) (step S5). Then, the control unit 20 generates the pulse signal A (FIG. 3) based on the distribution angle α and sends it to the switch unit 40 to turn on / off the switch unit 40 (step S6).

In this way, the control section 20 controls the switch section 40.

Next, the operation of this embodiment will be described.

Based on the voltage V ₁ and the current I ₁ detected by the detection unit 10, the control unit 20 always controls the control target point 107 (FIG. 2).
The voltage V _r of V is monitored. Then, when the difference between the voltage V _r and the specified voltage becomes larger than the dead band width ε, the distribution rate k is calculated,
From this, the distribution angle α is calculated, and the pulse signal A (FIG. 3) is generated based on this distribution angle α. At this time, the control unit 2
0 means that if the voltage V _{r at} the control target point 107 (FIG. 2) decreases, the distribution angle α increases, and conversely, if the voltage V _r increases,
Reduce the distribution angle α.

The switch section 40 is turned on / off by the pulse signal A, and the input voltage V induced by the voltage inducing section 30 is generated.
_From voltage V ₂ proportional to _S to pulsed voltage V ₃ (Fig. 3)
To generate. The filter unit 50 extracts the fundamental wave voltage V ₄ from the voltage V ₃ .

The fundamental wave voltage V ₄ and the distribution angle α have a substantially linear relationship, and the fundamental wave voltage V ₄ is substantially proportional to the distribution angle α. Accordingly, when the distribution angle α changes from 0 to β, the fundamental wave voltage V ₄ changes from 0 to V ₂ .

The voltage coupling unit 60 adds the fundamental wave voltage V ₄ thus obtained to the input voltage V _S. As a result, the output voltage V _{L of} which the voltage has been adjusted is sent from the output terminals 3 and 4 to the high-voltage power distribution line 101 (FIG. 2). This voltage is
The voltage drops in the high-voltage power distribution line 101 (FIG. 2), and the control target point 107 becomes a voltage of a predetermined magnitude.

In this way, according to the first embodiment, the voltage at the control target point 107 (FIG. 2) can be adjusted. At this time, since the fundamental wave voltage V ₄ and the distribution angle α have a substantially linear relationship, the control by the control unit 20 and the circuit configuration of the device are simplified.

Further, since it is possible to perform the compensation of the voltage drop at the peak time and the compensation of the voltage rise at the midnight time by one device, it is economical.

In addition, even when the power source side and the load side are switched due to switching of the high-voltage distribution system, etc.
Since the voltage can be raised or lowered by the voltage adjusting device, it is possible to deal flexibly.

Further, since the voltage regulator of the first embodiment does not perform mechanical switching, the voltage can be compensated up and down at high speed, and by adding the fundamental wave voltage V ₄ , the voltage can be raised or lowered. Since compensation is performed, generation of higher harmonic components can be prevented.

In this embodiment, the lowest order of the harmonic voltage generated by reducing the control period β

[Equation 8] The filter unit 50 can easily remove higher harmonic components.

[Second Embodiment] FIG. 6 shows a second embodiment of the present invention.
It is a block diagram showing. In the second embodiment, the wiring of the voltage coupling unit 60 of the first embodiment is changed. That is, the terminals 61 and 62 of the voltage coupling unit 60 are replaced with each other.
As a result, the equivalent circuit of FIG. 6 becomes as shown in FIG. From this equivalent circuit, the voltage adjustment amount is

[Equation 9] Becomes At this time, X _L b _L to select the X _L to be sufficiently smaller than the kV _2.

At normal power peak,

[Equation 10] And In this case, during normal power peaks,

[Equation 11] Is applied to the voltage coupling unit 60 in the boosting direction, and at midnight,

[Equation 12] Then, since the voltage shown in (9) is applied in the step-down direction,
Voltage adjustment is performed.

There are the following methods for adjusting the voltage. In one method, as shown in FIG. 8, instead of the inductance 51, an inductance 54 whose impedance can be changed is used. Then, the voltage is adjusted by changing the inductance 54.

In another method, as shown in FIG.
A series circuit of the capacitor 55 and the switch 56 is connected in parallel with the capacitor 53. Then, the adjustment capacitor 55 is turned on and off by turning on and off the switch 56.
Adjust the voltage by connecting to. At this time, the switch 56 may be a mechanical switch or a semiconductor switch.

[Third Embodiment] FIG. 10 is a block diagram showing a third embodiment of the present invention. In the third embodiment, between the transformer 31 and the capacitor 32 of the voltage inducing section 30 of the first embodiment,
Switches 33 and 34 are inserted. Switch 33
One terminal 31A of the transformer 31 is switched to one terminal 32A or the other terminal 32B of the capacitor 32.
The switch 34 connects the other terminal 31B of the transformer 31 to one terminal 32A of the capacitor 32 or the other terminal 32B.
Switch to B. Then, when the switch 33 is pushed to the side a, the switch 34 is also pushed to the side a and the switch 33
When is pushed to the b side, the switch 34 is also pushed to the b side.

In the third embodiment, when the switches 33 and 34 are tilted to the side a, the same state as in FIG. 1 is obtained.
The voltage adjustment amount is given by the equation (5). Further, when the switches 33 and 34 are turned to the b side, the polarity of kV ₂ is reversed, so the voltage adjustment amount is

[Equation 13] Becomes Therefore,

[Equation 14] Then, at the time of normal power peak, the imaginary part b _L is negative, so that a voltage is applied in the boosting direction. At midnight, on the contrary, the imaginary part b _L becomes positive, so that a voltage is applied in the step-down direction.

According to the third embodiment, since the voltage can be stepped up or down by switching the switches 33 and 34, the voltage adjustment range is widened.

Further, in the third embodiment, if the voltage adjustment range is constant, the voltage V ₂ can be reduced, so that the capacitance required for the switch section 40 can be reduced.

[Fourth Embodiment] FIG. 11 is a block diagram showing a fourth embodiment of the present invention. In the fourth embodiment, the terminals 61 and 62 of the voltage coupling unit 60 of the third embodiment are replaced with each other. In the fourth embodiment, in selecting the circuit constant,

[Equation 15] And, and applies to those that need to be sufficiently small X _L. In the fourth embodiment, when the switches 33 and 34 are tilted to the a side,

[Equation 16] Becomes Also, when the switches 33 and 34 are tilted to the b side,

[Equation 17] Becomes

According to the fourth embodiment, as in the third embodiment, the switches 33 and 34 are switched and the voltage coupling section 60 is used.
Thus, the voltage can be boosted / decreased and the voltage adjustment range can be further widened as compared with the third embodiment.

[Fifth Embodiment] FIG. 12 is a block diagram showing a fifth embodiment of the present invention. The fifth embodiment is the same as the first embodiment.
Instead of the transformer 31 of the, tap 35 for input switching
The transformer 35 with A, 35B and 35C is used. FIG. 13 shows an equivalent circuit of the fifth embodiment. In the transformer 35, when the voltage V _S is applied to the tap 35B, the voltage V _H is generated between the tap 35B and the tap 35C.

In Example 5,

[Equation 18] Then, the voltage adjustment amount is

[Formula 19] Becomes However,

[Equation 20] Is. The output voltage V _L is

[Equation 21] As a result, the adjustment voltage is

[Equation 22] Next, as compared with Examples 1 to 4 mentioned above, only the voltage "-V _H" in (22), the voltage adjustment is performed effectively.

For example, in the fifth embodiment, when the normal peak voltage is adjusted,

[Equation 23] And Also,

[Equation 24] Since,

[Equation 25] Only boosting is performed.

When adjusting the voltage at midnight, V _H
By keeping the value of

[Equation 26] Only the buck is done. At this time, the maximum adjustment amount in the step-down direction is

[Equation 27] Becomes

In the fifth embodiment, the voltage of "-V _H " is adjusted by switching the taps 35A, 35B and 35C.

[Sixth Embodiment] FIG. 14 is a block diagram showing a sixth embodiment of the present invention. In the sixth embodiment, the phase control unit 7 is provided between the voltage inducing unit 30 and the switch unit 40 of the first embodiment.
0 is inserted. The phase controller 70 includes a thyristor element 71 that is turned on and off under the control of the controller 20, and a capacitor 72 that is connected in series to the thyristor element 71.

According to the phase control unit 70 of the sixth embodiment, the reactive power that greatly affects the voltage fluctuation is compensated. For example, it is possible to compensate for a voltage flicker that occurs when a large-capacity electric motor is started or when the load power of an electric furnace or the like suddenly changes. With the composite type voltage regulator of the sixth embodiment, more effective voltage regulation becomes possible.

In the sixth embodiment, the thyristor element 71 is used.
Alternatively, a semiconductor AC switch may be used.

[0060]

As described above, according to the present invention, when the voltage applied to the load changes, the control means detects this variation from the detection result of the detection means. Then, the control means controls the switch means so that the voltage received by the load becomes a predetermined voltage, and changes the pulse width of the pulsed voltage generated by the switch means. The filter means extracts a voltage having the same frequency as the voltage applied to the load from the pulsed voltage, and the coupling means applies this voltage to the voltage supplied to the load.

As a result, the voltage fluctuation can be suppressed and the influence of the resistance up to the load can be prevented. Further, since the control means controls the pulse width according to the change in the voltage applied to the load, the voltage can be adjusted at high speed and continuously. Further, in the present invention, if the speed of switching the voltage waveform is increased, the generated harmonic component becomes a high-order component that can be easily removed by a filter, so that the harmonic component is not generated during voltage adjustment. It can be easily prevented.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an application example of the first embodiment.

FIG. 3 is a waveform diagram of a pulse signal and a voltage from a switch unit.

FIG. 4 is a diagram showing an equivalent circuit of the first embodiment.

FIG. 5 is a flowchart showing a control procedure of a control unit.

FIG. 6 is a block diagram showing a second embodiment of the present invention.

FIG. 7 is a diagram showing an equivalent circuit of the second embodiment.

FIG. 8 is a diagram showing an equivalent circuit for adjusting voltage by adjusting inductance in FIG. 6;

FIG. 9 is a diagram showing an equivalent circuit for adjusting the voltage by adjusting the capacitor in FIG. 6;

FIG. 10 is a block diagram showing a third embodiment of the present invention.

FIG. 11 is a block diagram showing a fourth embodiment of the present invention.

FIG. 12 is a block diagram showing a fifth embodiment of the present invention.

FIG. 13 is a diagram showing an equivalent circuit of the fifth embodiment.

FIG. 14 is a block diagram showing a sixth embodiment of the present invention.

FIG. 15 is a circuit diagram showing an example of a conventional voltage regulator.

FIG. 16 is a circuit diagram showing another example of a conventional voltage regulator.

17 is a diagram showing a waveform of a voltage applied to the reactor of FIG.

[Explanation of symbols]

 10 detection part 20 control part 30 voltage induction part 40 switch part 50 filter part 60 voltage coupling part

Claims (1)

[Claims] 1. A voltage adjusting device, which is used by being inserted between a power supply side and a load and which adjusts an AC voltage supplied to the load, detects an AC voltage and an AC current supplied to the load. Detecting means, inducing means for inducing an alternating voltage that is approximately proportional to the alternating voltage supplied to the load, and repeating the conducting state and the non-conducting state to change the alternating voltage from the inducing means to a pulsed alternating voltage. Switch means for converting into a pulsed AC voltage, filter means for extracting an AC voltage of the same frequency as the AC voltage supplied to the load from the pulsed AC voltage, and the filter means for extracting the AC voltage supplied to the load A coupling means for applying an alternating voltage, and a magnitude of the alternating voltage received by the load from the alternating voltage and the alternating current detected by the detecting means, and the calculated alternating voltage. A voltage adjusting device comprising: a control unit that controls the switching unit so that the magnitude of the pressure becomes a predetermined amount and changes the width of the pulse width of the pulsed AC voltage.