JPH11136945A - Transformer and operation thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability and operation rate and also adjust phase by providing a function to stabilize a mechanical voltage regulating mechanism in the transformer and keep constant a voltage in the negative side even when a voltage value of AC system is varied. SOLUTION: A stabilized voltage regulation type transformer 3 is composed of coils 5, 6, 7 electro-maganetically coupled in series via an iron core 4, a capacitor 8 connected in series with the coil 5, an AC voltage detector 14 and a power supply 9. The power supply 9 obtains phase information of a voltage Vs of the AC power supply system 1 from the AC voltage detector 14 and also obtains a control voltage V3 from the coil 7 to control a voltage Vc across terminals of capacitor 8 and the voltage V1 across terminals of coil 5 is adjusted so that the voltage V2 across the terminals of coil 6 becomes equal to the value requested by the AC load system 2. Thereby, the voltage regulating mechanism is stabilized to improve reliability and operation rate and also voltage amplitude and phase of the AC load system can be adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transformer, and more particularly to a transformer having a function of controlling a power flow state on a load side.

[0002]

2. Description of the Related Art In a conventional transformer, when adjusting a voltage of an AC load system, a tap provided on a winding on a primary side or a secondary side is mechanically switched to gradually change a load voltage. I was adjusting.

[0003]

Therefore, the operating speed is as slow as several tens of seconds, and the phase cannot be adjusted only by the voltage amplitude as a function. Furthermore, the mechanical life was short and there were many troubles.

SUMMARY OF THE INVENTION An object of the present invention is to stabilize a mechanical voltage adjusting mechanism in a transformer, improve reliability and operation speed, and adjust not only a voltage amplitude but also a phase. Is also to make it available.

[0005]

In order to achieve the above object, according to the present invention, in a transformer for converting an AC voltage to a predetermined voltage value and supplying power to a load, even if the voltage value of the AC system fluctuates. This is provided with a function of keeping the voltage on the load side constant.

In order to achieve the above object, according to the present invention, there is provided an AC load system comprising: a first transformer winding connected to each phase terminal of an AC power supply system; and an electromagnetically coupled first transformer winding. A second transformer winding connected to each phase terminal of the transformer between the first transformer winding and the AC power supply system, or between the second transformer winding and the AC load system. A capacitor is provided in series with the first or second transformer winding, and the magnitude or phase of the terminal voltage of the capacitor is changed by a power supply device provided in parallel between the terminals of the capacitor. Alternatively, the phase is maintained at a value required by the AC load system or the AC power supply system.

In order to achieve the above object, according to the present invention, a third transformer winding electromagnetically coupled to a first transformer winding and a second transformer winding is provided to change a terminal voltage of a capacitor. The input power of the power supply device to be obtained is obtained from an AC power supply system via a third transformer winding.

In order to achieve the above object, according to the present invention, a power supply device includes a first power conversion circuit for converting AC power obtained from a third transformer winding into DC power, and a first power conversion circuit. It comprises a power storage means for storing DC power obtained as an output of the circuit, and a second power conversion circuit for converting the DC power of the power storage means into AC power and operating the terminal voltage of the capacitor.

In order to achieve the above object, in the transformer according to the present invention, the first power conversion circuit generates a negative-phase current of a harmonic current generated by the AC load system and converts the negative-phase current into a third current. In this case, the harmonic current flowing from the AC load system into the AC power supply system is suppressed by injecting the AC power supply system through the transformer winding.

In order to achieve the above object, in the transformer of the present invention, a DC power generation facility or a power storage facility is connected to a terminal of the power storage means, and a DC power generation facility or a power storage facility is connected to an AC power supply system. Power interchange.

In order to achieve the above object, in the transformer of the present invention, a transformer is installed at each terminal of an AC transmission line, and an amplitude difference or a phase difference of each transformer output voltage is adjusted in cooperation with each other. In this way, the power interchange between the AC power systems is operated at a high speed to realize stable operation of the entire AC system or high power factor transmission.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes an AC power supply system, 2 denotes an AC load system, and 3 denotes a static voltage adjustment type transformer to which the present invention is applied. The quiescent voltage-adjustable transformer 3 includes windings 5, 6, 7, electromagnetically coupled to each other via an iron core 4, a capacitor 8 connected in series with the winding 5, and an AC voltage detector 1.
4, the power is obtained from the AC power supply system 1 via the winding 7 and the voltage Vc between the terminals of the capacitor 8 is manipulated so that the voltage V2 between the terminals of the winding 6 becomes a value required by the AC load system 2. 5
The power supply 9 adjusts the inter-terminal voltage V1.

FIG. 2 shows the principle of operation of the static voltage adjustment type transformer 3 shown in FIG. In this figure, the voltage V1 between the terminals of the winding 5 is obtained by vectorwise adding the voltage Vs of the AC power supply system and the voltage Vc between the terminals of the capacitor 8, and changes the magnitude | Vc | of the Vc and the phase θ1. Thus, the magnitude and phase of V1 can be changed. Since the winding 6 is electromagnetically coupled to the winding 5, the voltages V2 and V1
Is proportional to the number of turns of the winding 6 and the winding 5 is n, V2
Is (n · V1). Therefore, the voltage V2 can be adjusted to the magnitude and phase required by the AC load system 2 by changing Vc. Here, the voltage waveform signal V0 obtained via the AC voltage detector 14 in FIG. 1 is used by a control circuit in the power supply device 9 to obtain phase information of the voltage Vs of the AC power supply system 1.

According to this embodiment, the mechanical voltage adjusting mechanism of the conventional transformer is stationary, reliability and operation speed are improved, and not only the voltage amplitude but also the phase of the AC load system can be adjusted. Thus, it is possible to provide a quiescent voltage-adjustable transformer.

FIGS. 3 and 4 show a modification of the present invention, in which the capacitor 8 in FIG. 1 is provided in series with the winding 6 on the AC load system side. The voltage vector diagram at this time is as shown in FIG. 4, and the voltage V4 of the AC load system is a voltage V2 between terminals of the winding 6 on the AC load system side and a capacitor voltage Vc.
Are vector-wise added. Therefore, Vc
By manipulating the magnitude | Vc |
Can be changed in size and phase. According to this modification, the same effect as in FIG. 1 can be obtained.

FIGS. 5, 6, and 7 show specific examples of the power supply device 9. FIG. In FIG. 5, the power supply device 9 includes a single-phase diode bridge circuit 10, a diode bridge circuit 10 including four diodes 10u, 10v, 10x, and 10y.
, And four self-extinguishing type switching elements 12u, 12v, 12x,
12y (in FIG. 5, the self-turn-off type switching element is
An inverter circuit 12 (shown by GBT elements),
It comprises a reactor 13 for smoothing the output current of the inverter circuit 12, an inverter control circuit 16, and an AC voltage detector 15. Diode bridge circuit 10
Rectifies the inter-terminal voltage V3 of the winding 7 and converts it to a DC voltage for output. The capacitor 11 stores the power output of the diode bridge circuit 10 and acts as a stable DC voltage source. The inverter circuit 12 outputs a rectangular-wave voltage Vi that is driven by the DC voltage Vd of the capacitor 11 and is pulse-width-modulated. The rectangular wave voltage Vi is supplied to the reactor 13
And the capacitor 8 to provide a smooth sinusoidal AC voltage Vc. Here, for electrical insulation between the capacitor 8 and the power supply device 9, the function of the reactor 13 can be realized by the leakage reactance of the insulating transformer.

Next, the operation principle of the inverter circuit 12 will be briefly described. The on / off operation of each switching element is
There are basically two modes of operation, one of which is 12
This is a mode in which u and 12y conduct and other elements are turned off. At this time, the output voltage Vi becomes Vi = Vd.
Another mode is a case where 12v and 12x are turned on and the other elements are turned off.
i = −Vd. These two modes are alternately repeated. By manipulating the duration of each mode, the amplitude and phase of the smoothed AC voltage Vc can be arbitrarily changed. The operation of the mode duration is performed by the control circuit 16.

FIG. 6 is a block diagram showing the function of the control circuit 16. In the figure, a block 16c is an oscillator for outputting a sine wave waveform, and its output waveform W1 is a voltage waveform signal V0 obtained through the AC voltage detector 15.
The phase difference θ1 from the voltage waveform Vs of the AC power supply system 1 in FIG. 1 and the voltage waveform V2 between the terminals of the winding 6 on the AC load system side in the example of FIG. A deviation Δθ from θr is obtained, and an operation signal C1 for the oscillator 16c is created by the phase control function 16b.

The blocks 16a, 16b, 16 described above
As a result, the closed loop system composed of c creates a sinusoidal waveform W1 having a phase of θr based on the voltage waveform V0.

The amplitude of W1 is constant, and is set to 1 here. Next, the voltage Vc between the terminals of the capacitor 8 is detected by the voltage detector 1.
5, the amplitude | Vc | of the Vc is obtained by the amplitude detection circuit 16
d, and a deviation ΔV from the amplitude command | Vcr | is created. The voltage control function creates a control signal C2 according to ΔV. The multiplier 16f generates a product W2 of C2 and W1. The subsequent blocks perform pulse width modulation to create a capacitor terminal voltage Vc according to the waveform of W2. 16
g denotes an oscillator for generating a triangular carrier waveform CW used for pulse width modulation, and a deviation ΔW between W2 and CW.
Is used as an input signal of the comparator 16h to obtain a pulse width modulation waveform S1. When the level of S1 is High,
The gate pulses G1u and G1y are generated by the gate logic 16i, and the switching elements 12u and 12y are turned on. When the level of S1 is Low,
Gate pulses G1v and G1x are generated, and switching elements 12v and 12x are turned on. Thus, the output voltage Vi of the inverter circuit 12 is obtained,
FIG. 7 shows operation waveforms for pulse width modulation. FIG. 7A shows the waveforms of the carrier waveforms CW and W2, and the comparator 16h operates according to the deviation to generate the signal S1 shown in FIG. Here, S1
Is High when W2 ≧ CW and Lo when W2 <CW
w The gate logic 16i operates the switching element according to the signal S1, and the voltage waveform Vi shown in (3) is output from the inverter circuit 12. Since Vi is smoothed by the reactor 13 and the capacitor 8, the voltage waveform between the terminals of the capacitor 8 becomes sinusoidal as shown by the broken line in (3). With the above method, the waveform of the voltage Vc between the terminals of the capacitor 8 can be changed arbitrarily.

FIGS. 8 and 9 show a modification of the power supply device 9, in which the diode bridge circuit 10 in FIG. 5 is constituted by a bridge circuit 17 composed of self-extinguishing elements 17u, 17v, 17x and 17y. With this configuration, it is possible to keep the voltage of the capacitor 11 constant and to suppress the harmonic current generated by the system load.
The bridge circuit 17 is hereinafter referred to as a converter circuit to distinguish it from an inverter circuit. The control system in FIG. 8 includes current detectors 18 and 19, an AC voltage detector 20,
It comprises a DC voltage detector 21 and a converter control circuit 22.

The operation of the control system will be described with reference to FIG. In the figure, a block 22c is an oscillator that outputs a sine wave waveform, and its output waveform W3 detects a phase difference θ2 from a voltage waveform V3 obtained via an AC voltage detector 20 by a phase difference detection circuit 22a. An operation signal C3 for the oscillator 22c is created by the phase control function 22b according to (-θ2). The closed loop system including the blocks 22a, 22b, and 22c described above has a sine wave waveform W synchronized with the voltage waveform V3.
Create 3. The amplitude of W3 is constant, and is set to 1 here. Next, the terminal voltage Vd of the capacitor 11 is obtained via the DC voltage detector 21, and a deviation ΔVd from the voltage command Vdr is created. The voltage control function 22d creates a control signal C4 according to ΔVd. The multiplier 22e creates an AC input current command ir given as a product of C4 and W3. Next, the AC input current i3 obtained through the current detector 19
Δir between i and ir is obtained, the deviation Δi is suppressed, and i3 is changed to i
A control signal C5 for approaching r is created by the control function 22f. Further, the current i2 of the AC load system is obtained by the current detector 18, and only the higher harmonic component ix is detected by the higher harmonic detection circuit 22g, the phase is reversed and added to C5 to generate the signal W4. Block of FIG. 6
Is a pulse width modulation system similar to. Here, 22h is an oscillator for generating a triangular carrier waveform CW2 used for pulse width modulation, and a pulse width modulation waveform S2 is obtained by using a deviation ΔW2 between W4 and CW2 as an input signal of the comparator 22i. . When the level of S2 is High,
The gate pulses G2u and G2y are generated by the gate logic 22j, and the switching elements 17u and 17y are turned on. When the level of S2 is Low, gate pulses G2v and G2x are generated, and the switching elements 17v and 17x are turned on. In this way, the voltage of the capacitor 11 is kept constant, the harmonic current included in the current i2 of the AC load system is canceled by the input current i3 of the converter circuit 17, and the harmonic component of the current i1 of the AC power system is suppressed. can do. Here, the reactor for smoothing the input current i3 of the converter circuit 17 is omitted, but the smoothing of the current is also possible by the leakage inductance between the windings, and the reactor may be omitted.

By applying this modification, it is possible to add a harmonic current suppressing function to the static voltage adjustment type transformer.

FIGS. 10 and 11 show an embodiment in which the present invention is extended to a three-phase system. FIG. 10 includes a three-phase AC power supply system 22, a three-phase system load 23, iron cores 24, 25, 26, windings 27 to 35, capacitors 36, 37, 38, an AC voltage detector, and a power supply device 39. FIG.
As a specific configuration example of the power supply device 39, the diode bridge circuit 40 and the inverter circuit 42 have a three-phase configuration by adding one phase to FIG.

FIG. 12 shows an application example when the present invention is used as a system stabilizing device. The example illustrated in FIG. 12 includes power generation facilities 49 and 50 and AC transmission systems 51 and 52, and the present invention is applied to the AC transmission system 52. Reference numeral 56 denotes a static voltage adjustment type transformer according to the present invention. 54,5
5 represents system impedance. The effects of the present invention will be described with reference to FIGS. As shown in FIG. 13, since the magnitudes and phases of the system voltages Vt1 and Vt2 can be arbitrarily changed, as shown in FIG.
Since t2) can be set to approximately 90 degrees in phase with respect to the voltages Vs1 and Vs2 of the power generation facilities 49 and 50, power transmission with a high power factor can be performed. Further, since the phase and magnitude of the voltage (Vt1−Vt2) can be controlled at high speed by the inverter circuit, even if an unstable phenomenon occurs in the other AC power transmission system 51,
This can be suppressed at high speed.

FIG. 15 shows a DC voltage part of the static voltage adjustment type transformer according to the present invention, for example, the capacitor 1 in FIG.
1 shows a system configuration in a case where a DC power supply facility such as a DC power generation facility or a power storage facility is connected to a terminal No. 1; an AC power supply system 59; an AC load system 60; , And a DC power supply 62. By configuring such a system, power can be interchanged between a DC power supply such as a photovoltaic power generation facility, a fuel cell, an uninterruptible power supply, a storage battery, and a superconducting energy storage, and an AC power supply system.

[0027]

According to the present invention, the mechanical voltage adjusting mechanism in the transformer can be eliminated, and not only the voltage amplitude but also the phase can be adjusted at high speed.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention.

FIG. 2 shows an embodiment of the present invention.

FIG. 3 shows another embodiment of the present invention.

FIG. 4 shows another embodiment of the present invention.

FIG. 5 is a configuration example of a power supply device of the present invention.

FIG. 6 is a configuration example of a power supply device of the present invention.

FIG. 7 is a configuration example of a power supply device of the present invention.

FIG. 8 is another configuration example of the power supply device of the present invention.

FIG. 9 shows another configuration example of the power supply device of the present invention.

FIG. 10 shows another embodiment of the present invention when extended to a three-phase system.

FIG. 11 shows another embodiment of the present invention when extended to a three-phase system.

FIG. 12 shows an example in which the present invention is used as a system stabilization device.

FIG. 13 shows an example in which the present invention is used as a system stabilization device.

FIG. 14 shows an example in which the present invention is used as a system stabilization device.

FIG. 15 shows an embodiment in which power is exchanged between the present invention and DC power supply equipment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... AC power supply system, 2 ... AC load system, 3 ... Static voltage adjustment type transformer, 4 ... Iron core, 5,6,7 ... Winding, 8,11
... Capacitor, 9 ... Power supply device, 10 ... Diode bridge circuit, 12 ... Inverter circuit, 13 ... Reactor, 1
4, 15, 20: AC voltage detector, 16: Control circuit, 1
7 bridge circuit, 18 19 current detector, 21 DC voltage detector, 22 converter control circuit.

Claims (7)

[Claims] 1. A transformer for converting an AC voltage into a predetermined voltage value and supplying power to a load, wherein the transformer is provided with a voltage adjusting function for keeping the voltage on the load side constant even when the voltage value of the AC system fluctuates. A transformer. 2. A first power supply connected to each phase terminal of an AC power supply system.
, And a second transformer winding electromagnetically coupled to the first transformer winding and connected to each phase terminal of an AC load system, wherein the first transformer winding A capacitor is provided in series with the first or second transformer winding between the second transformer winding and the AC load system, or in parallel between the terminals of the capacitor. The magnitude or phase of the terminal voltage of the capacitor is changed by the power supply device provided in the above, so that the voltage or phase of the AC load system is maintained at a value required by the AC load system or the AC power system. And transformer. 3. The transformer according to claim 1, further comprising a third transformer winding electromagnetically coupled to said first transformer winding and said second transformer winding, and changing a terminal voltage of said capacitor. The input power of a power supply device to be obtained is obtained from the AC power supply system via the third transformer winding. 4. The transformer according to claim 2, wherein said power supply device comprises: a first power conversion circuit for converting AC power obtained from said third transformer winding into DC power;
Power storage means for storing DC power obtained as an output of the power conversion circuit, and a second means for converting the DC power of the power storage means into AC power and operating the terminal voltage of the capacitor.
And a power conversion circuit. 5. The transformer according to claim 4, wherein the first power conversion circuit generates a negative-phase current of a harmonic current generated by the AC load system, and converts the negative-phase current into the third transformer. Injected into the AC power system through the winding,
A transformer, wherein a harmonic current flowing from the AC load system to the AC power supply system is suppressed. 6. The transformer according to claim 4, wherein a DC power generation facility or a power storage facility is connected to a terminal of the power storage means, and power is exchanged between the DC power generation facility or the power storage facility and the AC power supply system. A transformer characterized by being able to perform. 7. The operating method of the transformer according to claim 1 or 2, wherein the transformer according to claim 1 or 2 is installed at each terminal of an AC transmission line, and an amplitude of each transformer output voltage. A method for operating a transformer, wherein power interchange between AC power supply systems is operated at high speed by adjusting a difference or a phase difference in cooperation with each other.