JP2002165386A - Uninterruptible power supply apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent harmonic problems by pausing operations of a power converter when out flown a harmonic current to an AC power supply system. SOLUTION: In an uninterruptible power supply apparatus having a harmonic filter composed of reactors 2, 4 and a condenser 3 provided at an AC side of the power converter, failures of the harmonic filter are detected by a current detector 11 to detect a condenser current flowing through a condenser composing of the filter, a rectifier circuit 13 to convert the detected current detected by the detector 11 to a DC signal and a signal level determination circuit 15 to determine a level of an output signal from the circuit 13, so that the operation of an AC-DC converter of the power converter is paused on the basis of a determination result of the determination circuit 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an uninterruptible power supply.

[0002]

2. Description of the Related Art In an uninterruptible power supply, as a method of suppressing a harmonic current of an AC power supply system and improving a power factor, Fuji Timely Vol. 63, No. 6, issued on June 10, 1990. There is a system using a high power factor converter as described in PP399 to 405. The converter has a high power factor converter provided with a harmonic filter including a reactor and a capacitor on the AC input side of a PWM rectifier. -Data.

[0003]

In the above-described uninterruptible power supply, the harmonic current that increases when a failure occurs such as the opening of the capacitor circuit in the harmonic filter or the power converter, increases the harmonic current on the AC power supply side. Harmonic interference,
For example, there is a problem that a harmonic current may flow into the phase-advancing capacitor to cause a trouble such as heating of the capacitor.

[0004] The present invention has been made in view of such circumstances, and stops the operation of an uninterruptible power supply when a harmonic current flows into an AC power supply system, thereby preventing harmonic interference. The purpose is to:

[0005]

SUMMARY OF THE INVENTION An uninterruptible power supply according to the present invention is an AC power supply for converting AC power from an AC system into DC power.
A / DC converter, a storage battery connected to the output of the AC / DC converter, a power converter including a DC / AC converter for converting DC power of the AC / DC converter into AC power, and the power converter Uninterruptible power supply having a harmonic filter composed of a reactor and a capacitor provided on the AC side of the power converter to suppress a harmonic current flowing out of the converter into an AC system or a harmonic voltage applied to the AC system A power supply device, comprising: a failure detection unit configured to detect a failure of the harmonic filter; and a power converter operation stop unit configured to stop an operation of the power converter in response to a detection signal of the failure detection unit. Means are a current detector for detecting a capacitor current flowing through a capacitor constituting the harmonic filter, and a rectifier circuit for converting a detection signal of the current detector into a DC signal. And a signal level determination circuit for determining the level of the output signal of the rectifier circuit, based on the determination result of the signal level determination circuit of the power converter AC / DC
The operation of the conversion device is stopped.

[0006] With this configuration, according to the uninterruptible power supply of the present invention, when a failure of the harmonic filter is detected by the failure detecting means, the AC / DC converter is stopped by the power converter operation stopping means. Operation is stopped.

Therefore, when the harmonic filter fails, the operation of the AC / DC converter is stopped, so that an excessive harmonic current flows out to the AC system or an excessive harmonic voltage is applied to the AC system. Therefore, harmonic interference can be prevented.

Further, instead of the above failure detecting means, a harmonic detecting circuit for detecting a harmonic voltage generated based on the outflow of the harmonic current to the AC system side, and an output signal of the harmonic detecting circuit. The rectifier circuit may be configured to include a rectifier circuit that converts the signal into a DC signal and a signal level determination circuit that determines a level of an output signal of the rectifier circuit.

Further, instead of the failure detecting means, a harmonic detecting circuit for detecting a harmonic voltage generated based on the outflow of the harmonic current to the AC system side, and an output signal of the harmonic detecting circuit. The rectifier circuit may be configured to include a rectifier circuit that converts the signal into a DC signal and a signal level determination circuit that determines a level of an output signal of the rectifier circuit.

Further, the power converter operation stopping means includes:
It can be configured to include a logic circuit that takes a logical product of a judgment output of the signal level judgment circuit and a pulse output of a gate pulse generation circuit that generates a gate pulse to be supplied to the power converter.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the overall configuration of an uninterruptible power supply according to an embodiment of the present invention. In the figure, the main circuit of the uninterruptible power supply obtains DC power from the AC power supply 1 through the AC reactors 2 and 4, the capacitor 3 and the AC / DC converter 5. Driving the DC / AC converter 7 as a power source,
It is configured to supply AC power to a load 10 via an AC reactor 8 and a capacitor 9.

In FIG. 1, the fault detecting means includes a current detector 11 for detecting a current flowing to the AC system side, a filter 12, a rectifier circuit 13, a harmonic detection level setting circuit 14, a comparator 15, The power converter operation stopping means includes a gate pulse generation circuit 16 and an AND circuit 17.
And a gate drive circuit 18.

In the above configuration, when the input current of the uninterruptible power supply is detected by the current detector 11, its harmonic component is extracted by the filter 12. This harmonic component is rectified by the rectifier circuit 13, and the DC signal Vd and the harmonic detection level Vf 1 set by the harmonic detection level setting circuit 14 are compared in magnitude by the comparator 15, and are determined.
When ≧ Vf1, the harmonic detection signal K1 is set to a low level (hereinafter, referred to as L), the AND circuit 17 is turned off, and the gate pulse signal G of the gate pulse generation circuit 16 is turned off.
Stop output of

When Vd <Vf1, the harmonic detection signal K1 is set to a high level (hereinafter, referred to as H), the AND circuit 17 is turned on, and the gate pulse generation circuit 16 is turned on.
Is output.

Further, the gate drive circuit 18 amplifies the gate pulse signal G and supplies it to the AC / DC converter 5,
/ DC converter 5 is driven.

According to this embodiment, a harmonic current generated when the capacitor 3 or the AC / DC converter 5 constituting the harmonic filter fails is detected, and the operation of the power converter is performed based on the detected output. Is stopped, excessive harmonic current can be prevented from flowing out to the AC system, or excessive harmonic voltage can be prevented from being applied to the AC system.

FIG. 2 shows the configuration of another embodiment of the uninterruptible power supply to which the present invention is applied. This embodiment is different from the embodiment shown in FIG. 1 in that the detection point of the current detector 11 is on the capacitor 3 side of the harmonic filter and the capacitor circuit including the capacitor 3 is open. The determination level Vf1 of the harmonic component for determining the state;
A determination level Vf2 of a harmonic component for performing a state determination when the / DC converter 5 has failed or the capacitor 3 has deteriorated is set, and these set levels are compared with the level of the detected harmonic component. That is, the failure detection is performed by the determination. The other configuration is exactly the same as the configuration shown in FIG.

Note that the set value Vf1 is based on the point that the current flowing through the current detector 11 becomes smaller than the value flowing in the steady state when the capacitor circuit including the capacitor 3 is opened, and the steady-state current The set value Vf2 is selected as the lower limit of the level, and the set value Vf2 is the current level flowing in the steady state because the harmonic current flowing to the current detector 11 increases when the AC / DC converter 5 fails or the capacitor 3 deteriorates. Has been selected as the upper limit.

In the above configuration, the capacitor current flowing through the capacitor 3 is detected by the current detector 11, and the DC signal Vd obtained by the rectifier circuit 13 and the harmonic detection levels Vf1, Vf2 of the harmonic detection level setting circuits 14, 19 are obtained. Are compared and determined by the comparators 15 and 20.

During the operation of the AC / DC converter 5, Vd ≦ V
When f1, the harmonic detection signal K1 is set to L through the signal inversion circuit 21, the AND circuit 22, and the signal inversion circuit 23,
When Vd> Vf1, the signal inversion circuit 21 and the AND circuit 2
2. The harmonic detection signal K1 is at H level through the signal inversion circuit 23.
It is said.

When Vd ≧ Vf2, the harmonic detection signal K2 is set to L, and when Vd <Vf2, the harmonic detection signal K2 is set to H. Therefore, Vd ≦ Vf1 or Vd
When ≧ Vf2, the AND circuit 24 is turned off, the output of the gate pulse signal G from the gate pulse generation circuit 16 is stopped, and when Vf1 <Vd <Vf2,
That is, when the capacitor 3 or the AC / DC converter 5 constituting the harmonic filter is operating normally, the AND circuit 24 is turned on, and the gate pulse generation circuit 16 is turned on.
Output the gate pulse signal G.

In this embodiment, the same effects as those of the embodiment shown in FIG. 1 can be obtained.

Next, the configuration of another embodiment of the uninterruptible power supply to which the present invention is applied is shown in FIG. This embodiment differs from the embodiment shown in FIG. 1 in that the change of the harmonic component included in the input current of the uninterruptible power supply is indirectly obtained by the change of the input voltage. In FIG. 3, a harmonic detection circuit 25 including a series circuit including a capacitor and a resistor is connected in parallel with the capacitor 3 so that when the capacitor 3 or the AC / DC converter 5 constituting the harmonic filter fails. When the generated harmonic current flows into the harmonic detection circuit 25, the voltage value detected by the harmonic detection circuit 25 increases, and the rectification circuit 13
Becomes Vd ≧ Vf1, the harmonic detection signal K1 is set to L, the AND circuit 17 is turned off, and the output of the gate pulse signal G from the gate pulse generation circuit 16 is stopped. .

In this embodiment, the same effects as those of the embodiment shown in FIG. 1 can be obtained.

Next, the configuration of another embodiment of the uninterruptible power supply to which the present invention is applied is shown in FIG. This embodiment is different from the embodiment shown in FIG. 1 in that the detection point of the current detector 11 is changed to the output current instead of the input current of the uninterruptible power supply, and a capacitor or a harmonic filter is formed. The point is that the DC / AC converter 7, which is the power converter on the output side of the uninterruptible power supply, is stopped when the power converter fails. The rest of the configuration is exactly the same as that of the embodiment shown in FIG.

According to the present embodiment, a harmonic current generated when the capacitor 9 or the DC / AC converter 7 constituting the harmonic filter is out of order is detected, and the operation of the power converter is stopped. It is possible to prevent the wave current from flowing out to the load system or to apply an excessive harmonic voltage to the load system.

Next, a modification of the embodiment shown in FIG. 4 is shown in FIG. This embodiment differs from the embodiment shown in FIG. 4 in that the detection point of the current detector 11 is changed to the capacitor current flowing through the capacitor 9 in place of the output current of the uninterruptible power supply. The determination of the level of the harmonic component is performed in the same manner as in the embodiment shown in FIG.
The point is that the determination is made in comparison with f2.

In this embodiment, the same effects as in the embodiment shown in FIG. 4 can be obtained.

Next, another modification of the embodiment shown in FIG. 4 is shown in FIG. This embodiment differs from the embodiment shown in FIG. 4 in that the change of the harmonic component included in the output current of the uninterruptible power supply is indirectly obtained by the change of the output voltage.

In this embodiment, the same effects as in the embodiment shown in FIG. 4 can be obtained.

Next, an application example of the present invention is shown in FIG. In this embodiment, the DC / AC converter 7 is driven by the DC power of a DC power source 27 such as a solar cell and a fuel cell, and the AC power is supplied to the AC power generation equipment 26 via the AC reactor 8 and the capacitor 9.
This is an application of the embodiment shown in FIG. 4 to a power converter for supplying to a commercial AC power system including the above.

According to the present embodiment, a harmonic current generated when the capacitor 9 or the DC / AC converter 7 constituting the harmonic filter is out of order is detected, and the operation of the power converter is stopped. It is possible to prevent the wave current from flowing out to the commercial AC power system or applying an excessive harmonic voltage to the commercial AC power system.

Next, FIG. 8 shows a modification of the embodiment shown in FIG. This embodiment is different from the embodiment shown in FIG. 7 in that the detection point of the current detector 11 is changed to the capacitor current flowing through the capacitor 9 instead of the output current of the DC / AC converter 7. The determination of the level of the detected harmonic component is performed in the same manner as in the embodiment shown in FIG.
1 is that the determination is made in comparison with Vf2.

In this embodiment, the same effects as those of the embodiment shown in FIG. 7 can be obtained.

FIG. 9 shows another modification of the embodiment shown in FIG. This embodiment differs from the embodiment shown in FIG. 7 in that the change of the harmonic component included in the output current of the DC / AC converter 7 is obtained indirectly by the change of the output voltage. is there.

In this embodiment, the same effects as in the embodiment shown in FIG. 7 can be obtained.

[0037]

According to the present invention as described above,
Since the operation of the AC / DC converter is stopped when the harmonic filter fails, it is possible to prevent excessive harmonic current from flowing out to the AC system or application of excessive harmonic voltage to the AC system, Therefore, harmonic interference can be prevented.

[Brief description of the drawings]

FIG. 1 is a circuit showing a configuration of an embodiment of an uninterruptible power supply to which the present invention is applied.

FIG. 2 is a circuit diagram showing a configuration of another embodiment of the uninterruptible power supply to which the present invention is applied.

FIG. 3 is a circuit diagram showing a configuration of another embodiment of the uninterruptible power supply to which the present invention is applied.

FIG. 4 is a circuit diagram showing a modification of the embodiment shown in FIG.

FIG. 5 is a circuit diagram showing a modification of the embodiment shown in FIG.

FIG. 6 is a circuit diagram showing another modification of the embodiment shown in FIG. 4;

FIG. 7 is a circuit diagram showing an application example of the present invention.

8 is a circuit diagram showing a modification of the embodiment shown in FIG.

FIG. 9 is a circuit diagram showing another modified example of the embodiment shown in FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC power supply 2 Reactor 4 Reactor 8 Reactor 3 Capacitor 9 Capacitor 5 AC / DC converter 6 Storage battery 7 DC / AC converter 10 Load 11 Current detector 12 Filter 13 Rectifier circuit 14 Harmonic detection level setting circuit 19 Harmonic detection level Setting circuit 15 Comparator 16 Gate pulse generation circuit 17 Logical product circuit 22 Logical product circuit 24 Logical product circuit 18 Gate drive circuit 21 Signal inversion circuit 23 Signal inversion circuit 25 Harmonic detection circuit 26 AC power generation equipment 27 DC power source

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shoji Toyoda 3-1-1, Sachimachi, Hitachi-City, Ibaraki Prefecture Inside the Hitachi Works, Hitachi, Ltd. (72) Tomoaki Mino 3-1-1 Sachimachi, Hitachi-City, Ibaraki Prefecture No. 1 Inside Hitachi, Ltd. Hitachi Plant (72) Inventor Yoshihiro Taniguchi 3-1-1, Sakaimachi, Hitachi City, Ibaraki Pref. Inside Hitachi Plant, Hitachi Ltd. F-term (reference) 5G015 FA06 GA04 HA16 JA13 JA34 JA35 JA52 5H007 AA08 BB05 CC01 DB01 DC02 DC04 DC05 GA08

Claims (4)

[Claims] 1. An AC / DC converter for converting AC power from an AC system into DC power, a storage battery connected to an output of the AC / DC converter, and DC power of the AC / DC converter into AC power. A power converter having a DC / AC converter for conversion; and an AC side of the power converter for suppressing a harmonic current flowing from the power converter into an AC system or a harmonic voltage applied to the AC system. In an uninterruptible power supply having a harmonic filter including a reactor and a capacitor provided in, a failure detection unit that detects a failure of the harmonic filter,
Power converter operation stopping means for stopping the operation of the power converter in response to a detection signal of the failure detecting means, wherein the failure detecting means detects a capacitor current flowing through a capacitor constituting the harmonic filter. A current detector, a rectifier circuit that converts a detection signal of the current detector into a DC signal, and a signal level determination circuit that determines a level of an output signal of the rectifier circuit; The uninterruptible power supply device is characterized in that the means stops the operation of the AC / DC converter of the power converter based on a result of the determination by the signal level determination circuit. 2. An AC / DC converter for converting AC power from an AC system into DC power, a storage battery connected to an output of the AC / DC converter, and DC power of the AC / DC converter into AC power. A power converter having a DC / AC converter for conversion; and an AC side of the power converter for suppressing a harmonic current flowing from the power converter into an AC system or a harmonic voltage applied to the AC system. In an uninterruptible power supply having a harmonic filter including a reactor and a capacitor provided in, a failure detection unit that detects a failure of the harmonic filter,
Power converter operation stopping means for stopping the operation of the power converter in response to the detection signal of the failure detecting means, wherein the failure detecting means is generated based on the outflow of the harmonic current to the AC system side. A harmonic detection circuit that detects a harmonic voltage, a rectifier circuit that converts an output signal of the harmonic detection circuit into a DC signal, and a signal level determination circuit that determines a level of the output signal of the rectifier circuit. An uninterruptible power supply device, wherein the power converter operation stopping means stops the operation of the AC / DC converter of the power converter based on the determination result of the signal level determination circuit. 3. An AC / DC converter for converting AC power from an AC system into DC power, a storage battery connected to an output of the AC / DC converter, and DC power of the AC / DC converter into AC power. A power converter having a DC / AC converter for conversion; and an AC side of the power converter for suppressing a harmonic current flowing from the power converter into an AC system or a harmonic voltage applied to the AC system. In an uninterruptible power supply having a harmonic filter including a reactor and a capacitor provided in, a failure detection unit that detects a failure of the harmonic filter,
Power converter operation stopping means for stopping the operation of the power converter in response to the detection signal of the failure detecting means, wherein the failure detecting means is generated based on the outflow of the harmonic current to the AC system side. A harmonic detection circuit that detects a harmonic voltage, a rectifier circuit that converts an output signal of the harmonic detection circuit into a DC signal, and a signal level determination circuit that determines a level of the output signal of the rectifier circuit. An uninterruptible power supply device, wherein the power converter operation stopping means stops the operation of the AC / DC converter of the power converter based on the determination result of the signal level determination circuit. 4. The power converter operation stopping means includes a logic circuit that calculates a logical product of a determination output of the signal level determination circuit and a pulse output of a gate pulse generation circuit that generates a gate pulse to be supplied to the power converter. The uninterruptible power supply according to any one of claims 1 to 3, comprising: