JP5166183B2 - Uninterruptible power supply and power supply method using uninterruptible power supply - Google Patents

Description

  The present invention relates to an uninterruptible power supply and an improved power supply method using the uninterruptible power supply.

  As a conventional uninterruptible power supply, for example, an input conversion unit AD, an electric energy source B connected to the output side of the input conversion unit AD, an inverter that converts direct current into alternating current, or a DC-DC that converts direct current into direct current In the apparatus provided with the converter as the output conversion unit DA, a capacitor is disposed at the power receiving end of the input conversion unit AD, and a signal obtained from the current flowing through the commercial load 2 and a signal obtained from the voltage applied to the input conversion unit The control circuit ADC is provided with an active filter device on the input side and an inverter or rectifier on the output side, and supplies AC or DC power from the energy source B to the commercial load 2 during a power failure of the AC power source 1. Those are known (for example, see Patent Document 1).

JP-A-6-86557 (paragraph numbers 0012 to 0016 and FIG. 1)

  Conventional uninterruptible power supplies are configured as described above, and it is common to use the voltage of a commercial power supply that is an AC power supply for power failure detection and operation switching operation signals, but there is a problem that detection is delayed. is there. For this reason, when switching the power supply from the AC power supply to the power supply from the power storage device that stores DC power when the AC power supply is stopped, a switching time due to a detection delay is required, and the power supply to the load is interrupted during that time As a countermeasure to avoid this, there is a constant inverter power feeding method in which power is fed by an uninterruptible power supply even when the AC power is healthy, but there is a problem that efficiency is low.

  The present invention has been made to solve the above-described problems, and always uses an AC power supply when the AC power supply is healthy without using an inverter power supply system, and AC power supply when the AC power supply stops. An object of the present invention is to obtain an uninterruptible power supply capable of avoiding interruption of power supply to a load when switching power supply from the power supply to power supply from a power storage device. Also, to provide a power supply method by an uninterruptible power supply that can avoid interruption of power supply to a load when the power supply from the AC power supply is switched to the power supply from the power storage device when the AC power supply is stopped. Objective.

In the uninterruptible power supply according to the present invention,
A DC converter, a power storage device, an AC converter, and a controller;
The DC converter converts power from an AC power source into DC output,
The power storage device has a storage battery and a capacitor, and the storage battery and the capacitor are connected in parallel and connected to a DC conversion device to store DC power,
The AC converter is connected to the DC converter and converts DC to AC,
The control device controls the supply of the compensation current from the power storage device and the AC conversion device to the load so as to cancel the harmonic component in the load current flowing through the load while supplying the AC power from the AC power source. Based on the above, it is determined whether an abnormality has occurred in the AC power supply, and when it is determined that an abnormality has occurred, the supply of AC power from the AC power supply to the load is stopped and the DC power stored in the storage battery is converted to AC by the AC converter. Control to supply to the load.

In the power supply method by the uninterruptible power supply according to the present invention,
AC power from an AC power source is supplied to the load and converted to direct current so that it is stored as direct current power in a power storage device in which a storage battery and a capacitor are connected in parallel, and harmonic components in the load current flowing to the load are canceled out. When the AC converter connected to the power storage device is controlled to supply a compensation current to the load, the presence or absence of an abnormality in the AC power source is determined based on the compensation current, and the AC is transferred from the AC power source to the load. The supply of power is stopped, and the DC power stored in the storage battery is converted to AC by an AC converter and supplied to a load.

In the uninterruptible power supply according to the present invention,
A DC converter, a power storage device, an AC converter, and a controller;
A DC converter, a power storage device, an AC converter, and a controller;
The DC converter converts power from an AC power source into DC output,
The power storage device has a storage battery and a capacitor, and the storage battery and the capacitor are connected in parallel and connected to a DC conversion device to store DC power,
The AC converter is connected to the DC converter and converts DC to AC,
The control device controls the supply of the compensation current from the power storage device and the AC conversion device to the load so as to cancel the harmonic component in the load current flowing through the load while supplying the AC power from the AC power source. Based on the above, it is determined whether an abnormality has occurred in the AC power supply, and when it is determined that an abnormality has occurred, the supply of AC power from the AC power supply to the load is stopped and the DC power stored in the storage battery is converted to AC by the AC converter. To control the supply to the load,
It is possible to obtain an uninterruptible power supply capable of avoiding interruption of power supply to the load when the power supply from the AC power supply is switched to the power supply from the power storage device when the AC power supply is stopped.

In the power supply method by the uninterruptible power supply according to the present invention,
AC power from an AC power source is supplied to the load and converted to direct current so that it is stored as direct current power in a power storage device in which a storage battery and a capacitor are connected in parallel, and harmonic components in the load current flowing to the load are canceled out. When the AC converter connected to the power storage device is controlled to supply a compensation current to the load, the presence or absence of an abnormality in the AC power source is determined based on the compensation current, and the AC is transferred from the AC power source to the load. Since the supply of power is stopped and the DC power stored in the storage battery is converted to AC by the AC converter and supplied to the load,
It is possible to provide a power supply method using an uninterruptible power supply that can avoid interruption of power supply to a load when the power supply from the AC power supply is switched to the power supply from the power storage device when the AC power supply is stopped.

Embodiment 1 FIG.
1 to 3 show Embodiment 1 for carrying out the present invention, FIG. 1 is a configuration diagram showing the configuration of an uninterruptible power supply, and FIG. 2 is a waveform diagram for explaining the operation. FIG. 3 is an operation state diagram showing the operation of the uninterruptible power supply. In FIG. 1, power is supplied from a commercial power source 2 that is an AC power source to a load 6 via a power supply bus 3 and a bus breaker 5. On the other hand, the commercial power source 2 is stepped down to a predetermined voltage by the transformer 11 and supplied to the rectifier 12 as a DC converter.

  The direct current output rectified by the rectifier 12 and converted into direct current charges the storage battery 13. The storage battery 13 becomes a power source when the commercial power source 2 is powered off. The capacitor 14 is connected in parallel with the storage battery 13 and is similarly charged to store electric charges. The storage battery 13 and the capacitor 14 connected in parallel to each other are the power storage device in the present invention. In addition, the transformer 11 serves as the adjustment of the voltage supplied to the rectifier 12 and the insulation between the commercial power source 2 and the storage battery 13 simultaneously with the supply of power from the power supply bus 3 to the storage battery 13 and the capacitor 14.

  The inverter 15 serving as an AC converter converts DC to AC and outputs an inverter output current J2 that cancels the distortion current via the current smoothing reactor 16. The operation state control circuit 21 switches between the uninterruptible power supply control circuit 22 and the current distortion correction circuit 23 with a changeover switch 26. The uninterruptible power supply control circuit 22 controls the inverter 15 so as to operate as an uninterruptible power supply when the commercial power supply 2 fails. The current distortion correction circuit 23 detects the distortion current included in the load power supply current J1, and controls the inverter 15 to output the inverter output current J2 that cancels the distortion current. The operation state control circuit 21, the uninterruptible power supply control circuit 22, the current distortion correction circuit 23, the changeover switch 26, and a power supply abnormality detection circuit 36, which will be described later, are control devices in the present invention.

  A load feeding current detection HCT (Hall current detector) 31 detects a feeding current J1 including current distortion. The distortion correction current detection HCT 32 detects the inverter output current J2. The power source current detection HCT 33 detects the commercial power source current J3. The HCT converts the strength of the magnetic field generated around the current to be measured into a voltage signal by a Hall element and outputs the voltage signal. A PT (instrument transformer) 36 detects the voltage of the commercial power source 2. The power supply abnormality detection circuit 36 serving as the abnormality determination means outputs a bus disconnection command S5 and an operation state switching command S26 when it is determined that a commercial power failure has occurred.

  Next, the operation will be described. In FIG. 1, power is supplied from the commercial power supply 2 to the load 6 through the power supply bus 3, and at the same time, the voltage is adjusted from the commercial power supply 2 by the transformer 11 and the DC power converted from AC to DC by the rectifier 12 is stored in the storage battery 13 and Store in capacitor 14. The load supply current J1 is detected by the load supply current detection HCT31, the inverter output current J2 is detected by the distortion correction current detection HCT32, and the commercial power supply current J3 is detected by the power supply current detection HCT33.

  When the load feeding current J1 detected by the load feeding current detection HCT 31 is distorted, the distortion current included in the load feeding current J1 is extracted by the current distortion correction circuit 23, the DC current is supplied from the capacitor 14, and the inverter 15 to convert from direct current to alternating current. At the same time, the inverter 15 is controlled to output the inverter output current J2 as a compensation current for canceling the distortion current (harmonic current) by the current distortion correction circuit 23, and the inverter output current J2 is supplied to the power supply bus 3. The inverter output current J2 cancels the distortion current included in the load power supply current J1, thereby compensating the commercial power supply current J3 and improving the waveform with less distortion. That is, in this state, the rectifier 12, the capacitor 14, and the inverter 15 are controlled by the current distortion correction circuit 23 so as to function as an active filter.

  Next, the operation state switching operation will be described with reference to FIGS. Normally, the operation state control circuit 21 selects the current distortion correction circuit 23 (FIG. 2A), and the changeover switch 26 is switched to the current distortion correction circuit 23 side, and is in the state shown in FIG. In this state, for example, when an accident occurs in the commercial power supply 2 or the power supply bus 3 at time tl, a short-circuit current temporarily flows toward the accident point, and the load power supply current detected by the load power supply current detection HCT 31 is detected. J1 (FIG. 2C) is distorted, and similarly, the inverter output current J2 (FIG. 2D) detected by the distortion correction current detecting HCT 32 is also affected and increases. At this time, the waveform of the commercial power supply 2 is also distorted as shown in FIG.

  The power supply abnormality detection circuit 29 determines that an accident has occurred, that is, an abnormality has occurred in the AC power supply at the time t2 when the inverter output current J2 reaches the predetermined value A (FIG. 2 (d)), and the bus disconnection command S5 and the operating state switching command S26. Are output at time t3. The commercial power source 2 is shut off at the bus breaker 5 by the bus breaker command S5, and at the same time, the control by the current distortion correction circuit 23 at the driving state control circuit 21 by the uninterruptible power supply control circuit 22 at the operating state switching command S26. Switching to the control (FIG. 2A), the state shown in FIG. 3 is obtained. Since this switching operation is performed in a very short time, the inverter 15 can continuously perform power supply to the load 6 without interrupting operation and without power failure. That is, in this state, the rectifier 12, the storage battery 13, and the inverter 15 are controlled by the uninterruptible power supply control circuit 22 so as to function as an uninterruptible power supply.

  After starting operation as an uninterruptible power supply, the inverter 15 controlled by the uninterruptible power supply control circuit 22 converts DC power from the storage battery 13 into AC and supplies power to the load 6. When the commercial power supply 2 recovers from the power failure state, when the commercial power supply voltage detected by the PT 36 reaches a certain value, the bus breaker 5 is closed and the operation state control circuit 21 controls the uninterruptible power supply. The operation state is switched from the control by the circuit 22 to the control by the current distortion correction circuit 23, and the commercial power supply operation is started.

  The power supply abnormality detection circuit may determine that an abnormality has occurred in the AC power supply when the rate of change of the inverter output current J2 exceeds a predetermined value, and issue a bus disconnection command S5 and an operation state switching command S26. .

  According to this embodiment, without using an inverter power supply system at all times, power is supplied from the AC power supply when the AC power supply is healthy, and the DC power is stored as power supply from the AC power supply when the AC power supply is stopped due to an accident or the like. It is possible to avoid interruption of power supply to the load when switching to power supply from the power storage device.

It is a block diagram which shows the structure of the uninterruptible power supply which is Embodiment 1 of this invention. It is a wave form diagram for demonstrating operation | movement. It is an operation state figure showing operation of an uninterruptible power supply.

Explanation of symbols

2 Commercial power supply, 5 Bus breaker, 6 Load, 12 Rectifier, 13 Storage battery,
14 capacitors, 15 inverters, 21 operating state control circuit,
22 uninterruptible power supply control circuit, 23 current distortion correction circuit, 26 operation state switch,
29 Power supply abnormality detection circuit.

Claims (4)

A DC converter, a power storage device, an AC converter, and a controller;
The DC converter converts power from an AC power source into DC output,
The power storage device has a storage battery and a capacitor, and the storage battery and the capacitor are connected in parallel and connected to the DC converter to store DC power,
The AC converter is connected to the DC converter and converts DC to AC,
The control device supplies AC power to the load from the AC power source and supplies compensation current from the power storage device and the AC converter to the load so as to cancel harmonic components in the load current flowing through the load. The AC power supply is controlled based on the compensation current to determine whether an abnormality has occurred in the AC power supply. When it is determined that an abnormality has occurred, supply of the AC power from the AC power supply to the load is stopped and stored in the storage battery. The DC power is controlled to be converted into AC by the AC converter and supplied to the load.
Uninterruptible power system. The uninterruptible power supply according to claim 1, wherein the control device determines that an abnormality has occurred in the AC power supply when the compensation current exceeds a predetermined value. 2. The uninterruptible power supply according to claim 1, wherein the control device determines that an abnormality has occurred in the AC power supply when a rate of change of the compensation current exceeds a predetermined value. AC power from the AC power supply is supplied to the load and converted to DC, which is stored as DC power in a power storage device in which a storage battery and a capacitor are connected in parallel, and cancels harmonic components in the load current flowing through the load. And controlling the AC converter connected to the power storage device to supply a compensation current to the load, and determining whether or not an abnormality has occurred in the AC power source based on the compensation current and determining that an abnormality has occurred. An electric power supply method by an uninterruptible power supply device that stops supply of the AC power from a power source to the load and converts the DC power stored in the storage battery into AC by the AC converter and supplies the AC to the load.

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