JPH0956086A - Method for controlling uninterruptible power unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the operation reliability of an uninterruptible power unit which supplies electric power to a load from commercial power supply through a semiconductor switch when the commercial power supply is. normal and, when the commercial power supply is. interrupted, from an inverter by making the inverter charge a battery and operate an active filter to a load current. SOLUTION: An uninterruptible power unit 30 is provided with a frequency monitor circuit 31 which monitors the frequency of a commercial power supply 1 and, when the frequency deviates from the rated frequency of the commercial power supply by ±4%, makes a diesel power generator to operate surely by continuing the operation of the unit 30 by stopping charging operations and the operations of an active filter. When the frequency is restored to the rated frequency, the unit 30 restarts the charging operations and the operations of the active filter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention supplies electric power to a load from a commercial power source through a semiconductor switch when the commercial power source is healthy (hereinafter referred to simply as "normal time"), and an inverter from a storage battery when the commercial power source fails. The present invention relates to a control method of an uninterruptible power supply device that supplies power to a load via a power supply.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram showing a conventional example of a control method for an uninterruptible power supply of this type. In FIG. 5, 1 is a commercial power supply, 2 is a storage battery, 3 is a load, 10 is an uninterruptible power supply, and the uninterruptible power supply 10 is a circuit breaker 11, a semiconductor switch 12, a gate drive circuit 13, an electromagnetic contactor 1.
4, an inverter main circuit 15, a transformer 16, an AC reactor 17, a filter capacitor 18, and an inverter control circuit 21. In addition, the filter capacitor 18 is a filter that removes the switching noise generated due to the switching operation of the inverter main circuit 15.

The uninterruptible power supply system 10 shown in FIG. 5 operates as follows. First, the circuit board breaker 1
1 is closed, and the semiconductor switch 12 is made conductive by the gate drive circuit 13 to turn off the circuit breaker 11 from the commercial power source 1.
The power supply to the load 3 is started via the semiconductor switch 12, the electromagnetic contactor 14 is closed, and the inverter main circuit 15 starts the charging operation of the storage battery 2 by the inverter control circuit 21 to generate the harmonics generated from the load 3. The start-up is completed by starting the active filter operation that absorbs the wave current and the reactive current, and the uninterruptible power supply 10 enters the normal state.

Here, as the active filter operation, a gate signal output from the inverter control circuit 21 which is adjusted based on the current of the load 3 detected by the current detector 22 is used to pass through the AC reactor 17 and the transformer 16. The output AC voltage of the inverter main circuit 15 is controlled. Next, at the time of a power failure of the commercial power supply 1, a power failure detection circuit (not shown) detects this, the gate drive circuit 13 shuts off the semiconductor switch 12, and the inverter control circuit 21 causes the storage battery 2 to the electromagnetic contactor 14 and the inverter main circuit. 1
5, Power is supplied to the load 3 through the transformer 16, the AC reactor 17, and the filter capacitor 18.

[0005]

For the purpose of installing this type of uninterruptible power supply, high reliability is required so that stable power can always be supplied to the load at any time. According to the above conventional uninterruptible power supply control method,
As a backup power source of the commercial power source while the commercial power source is out of power and the inverter is supplying power to the load, for example, when the start of the diesel generator is completed, the diesel generator is connected instead of the commercial power source, and the uninterruptible power source is connected. The inverter switches to the charging operation and the active filter operation described above on the assumption that the power failure has been resolved. However, since the capacity of the diesel generator is smaller than that of the commercial power source, there is a possibility that this frequency may fluctuate significantly while the diesel generator is operating, and the fluctuation cannot be followed by the charging operation and the active filter operation. There was a problem.

Further, since the output capacity of the inverter is selected as the capacity necessary for the commercial power source to supply the rated load in the event of a power failure, the inverter's output capacity is reduced during the charging operation and the active filter operation described above. When the capacity is close to the rated load and the power factor is poor, the output capacity of the inverter may be exceeded, resulting in overload and damage to the inverter due to heating.

Further, for example, if a commercial power source frequently suffers a power failure and is discharged in a state where the storage battery is not sufficiently charged, the storage battery may have a discharge end voltage and may not function as an uninterruptible power supply. An object of the present invention is to provide a control method for an uninterruptible power supply device that solves the above problems.

[0008]

[Means for Solving the Problems] When the commercial power source is healthy, power is supplied to the load through a semiconductor switch that supplies / shuts off the power from the commercial power source, and the inverter operates to charge the storage battery from the commercial power source. In the control method of the uninterruptible power supply device, which performs active filter operation that absorbs the harmonic current and reactive current generated from the load, and supplies power to the load from the storage battery via the inverter during a power failure of the commercial power supply. According to a first aspect of the present invention, the frequency of the commercial power source is monitored, and when the monitored frequency exceeds a first upper limit value or falls below a first lower limit value, the charging operation and the active filter operation are stopped and the monitoring is performed. The charging operation and the active filter operation are restarted after the specified frequency has recovered to the first upper limit value or lower, or has recovered to the first lower limit value or higher and the predetermined time period has elapsed. To.

The second invention is, in the control method of the uninterruptible power supply, monitoring the frequency of the commercial power supply,
When the monitored frequency exceeds the first upper limit, or the first
When the value is below the lower limit value of, the charging operation and the active filter operation are stopped, and the monitored frequency is recovered to be equal to or lower than the second upper limit value which is lower than the first upper limit value, or the second frequency higher than the first lower limit value. The charging operation and the active filter operation are restarted when the value returns to the lower limit or more.

In a third aspect of the present invention, in the control method of the uninterruptible power supply, the case temperature of the semiconductor switch element forming the inverter is detected, and when the detected case temperature exceeds the first set temperature. The active filter operation is suppressed within a capacity range smaller than the rated compensation capacity, and the active filter operation is stopped when the detected case temperature exceeds a second set temperature higher than the first set temperature.

Further, in a fourth aspect of the present invention, in the method for controlling an uninterruptible power supply, the semiconductor switch is shut off for a predetermined period while monitoring the terminal voltage of the storage battery when the commercial power source is healthy, Power is supplied to the load through the inverter, and when the terminal voltage of the storage battery becomes equal to or lower than the first set value within the predetermined period, or when the terminal voltage reaches the predetermined period, it is higher than the first set value. When it is below the second set value, this is displayed to the outside, and when the predetermined period is reached or when the terminal voltage of the storage battery is below the first set value, the semiconductor switch is turned on again, Power is supplied to the load from a commercial power source.

[0012]

According to the first aspect of the present invention, in the above-mentioned uninterruptible power supply, the frequency of the commercial power source is monitored, and when the monitored frequency deviates from the first upper limit value or the first lower limit value, the charging operation is performed. By stopping the active filter operation and restarting the charging operation and the active filter operation after the monitored frequency is recovered to the first upper limit value or the first lower limit value and a predetermined time period has elapsed, for example, commercial The operation can be continued even when the electric power of the diesel generator is supplied to the load instead of the power source.

According to the second invention, in the above-mentioned uninterruptible power supply, the frequency of the commercial power supply is monitored, and when the monitored frequency is out of the first upper limit value or the first lower limit value, the charging operation is performed. By stopping the active filter operation and restarting the charging operation and the active filter operation when the monitored frequency is recovered to the second upper limit value or the second lower limit value, for example, diesel power generation in place of commercial power supply The operation can be continued even when the electric power of the machine is supplied to the load.

According to the third aspect of the invention, the case temperature of the semiconductor switching element forming the inverter is detected, and when the detected case temperature exceeds the first set temperature,
The active filter operation is suppressed within a predetermined control range, and when the detected case temperature exceeds the second set temperature, the active filter operation is stopped to reduce the load capacity of the inverter and increase the temperature. It can be suppressed and the operation of this UPS can be continued.

Furthermore, according to the fourth aspect of the present invention, when the commercial power source is healthy, the terminal voltage of the storage battery is monitored for a predetermined period of time.
By disconnecting the semiconductor switch and supplying power from the storage battery to the load via the inverter, the state of the storage battery can be confirmed without stopping the operation of the uninterruptible power supply.

[0016]

EXAMPLES In the examples of the present invention described below,
Those having the same functions as those of the conventional example shown in FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted. The functions different from those of FIG. 5 will be mainly described. FIG. 1 is a configuration diagram of an uninterruptible power supply device showing a first embodiment of the present invention.

In the uninterruptible power supply 30 shown in FIG. 1, the frequency of the commercial power supply 1 is monitored by the frequency monitoring circuit 31, and when the monitored frequency deviates, for example, from ± 4% of the rated frequency, the inverter control circuit 32. By this, the charging operation of the storage battery 2 via the inverter main circuit 15 and the active filter operation for the current in the load 3 are stopped, the monitored frequency recovers within the range of ± 4%, and a predetermined time period is reached.
For example, the configuration is such that the charging operation and the active filter operation are restarted after 1 second has elapsed.

FIG. 2 is a block diagram of an uninterruptible power supply unit showing a second embodiment of the present invention. In the uninterruptible power supply device 40 shown in FIG. 2, the frequency of the commercial power supply 1 is monitored by the frequency monitoring circuit 41, and when the monitored frequency deviates, for example, from ± 4% of the rated frequency, the inverter control circuit 32.
Thus, the charging operation of the storage battery 2 via the inverter main circuit 15 and the active filter operation for the current in the load 3 are stopped, and the monitored frequency is, for example, ± 2% of the rated frequency.
The configuration is such that the charging operation and the active filter operation are restarted when the voltage recovers within the range.

The commercial power supply 1 shown in FIG. 1 or FIG.
The inverter control circuit 32 at the time of power failure operates in the same manner as the conventional inverter control circuit 21 of FIG. FIG. 3 is a configuration diagram of an uninterruptible power supply device showing a third embodiment of the present invention. In the uninterruptible power supply device 50 shown in FIG. 3, the case temperature of the semiconductor switch element forming the inverter main circuit 51 is changed from the temperature detection element such as a thermistor attached to the cooling body of the semiconductor switch element to the temperature detection circuit 52. Detected through, the detected temperature is, for example, 70 ℃
When the temperature exceeds the limit, the active filter operation is suppressed by the inverter control circuit 53 to compensate up to, for example, 50% of the rated compensation capacity, and when the detected temperature exceeds, for example, 80 ° C., the active filter operation is stopped. In this configuration, the burden capacity of the inverter main circuit 51 is reduced to suppress the temperature rise, and the operation of the uninterruptible power supply 50 is continued.

The rated compensation capacity is about 35% of the rated capacity in this type of uninterruptible power supply. Also, FIG.
Control circuit 53 at the time of power failure of the commercial power supply 1 in
Operates in the same manner as the conventional inverter control circuit 21 of FIG. FIG. 4 is a configuration diagram of an uninterruptible power supply device showing a fourth embodiment of the present invention.

In the uninterruptible power supply system 60 shown in FIG. 4, the storage battery monitoring circuit 51 monitors the terminal voltage of the storage battery 2 when the commercial power supply 1 is healthy, based on a command from the outside (not shown). For example, 6
The semiconductor switch 12 is cut off for a second, and the inverter control circuit 52 controls the storage battery 2 to the inverter main circuit 15 during this period.
Power is supplied to the load 3 via the
When the terminal voltage of is less than the discharge end voltage or when the terminal voltage of the storage battery 2 is less than 95% of the rated terminal voltage when reaching the 6 seconds, this is displayed externally and normal operation is resumed. It is configured to return to the
Make inspection easy.

[0022]

According to the present invention, the conventional uninterruptible power supply has a frequency monitoring circuit for monitoring the frequency of the commercial power supply, a temperature detection circuit for monitoring the temperature of the cooling body of the inverter main circuit,
By adding a storage battery monitoring circuit that monitors the terminal voltage of the storage battery, you can realize high reliability that can always supply stable power to the load at any time, and it is suitable as an uninterruptible power supply for various industrial machines and 0A equipment. is there.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an uninterruptible power supply device showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram of an uninterruptible power supply device showing a second embodiment of the present invention.

FIG. 3 is a block diagram of an uninterruptible power supply showing a third embodiment of the present invention.

FIG. 4 is a block diagram of an uninterruptible power supply showing a fourth embodiment of the present invention.

FIG. 5 is a configuration diagram of an uninterruptible power supply device showing a conventional example.

[Explanation of symbols]

1 ... Commercial power source, 2 ... Storage battery, 3 ... Load, 10, 30, 3
0, 50, 60 ... Uninterruptible power supply, 11 ... Circuit breaker,
12 ... Semiconductor switch, 13, 53 ... Gate driving circuit,
14 ... Electromagnetic contactor, 15, 51 ... Inverter main circuit, 1
6 ... Transformer, 17 ... AC reactor, 18 ... Filter capacitor, 21, 32, 53, 62 ... Inverter control circuit, 22 ... Current detector, 31, 41 ... Frequency monitoring circuit,
52 ... Temperature detection circuit, 61 ... Storage battery monitoring circuit.

Claims (4)

[Claims] 1. When the commercial power source is healthy, power is supplied to the load through a semiconductor switch that supplies / shuts off the power from the commercial power source, and the inverter operates to charge the commercial battery from the commercial power source and generate the load. In the control method of the uninterruptible power supply device that performs the active filter operation that absorbs the harmonic current and the reactive current, and during the power failure of the commercial power supply, the power is supplied to the load from the storage battery via the inverter. When the monitored frequency exceeds the first upper limit value, or
When the value is below the lower limit value of, the charging operation and the active filter operation are stopped, and the monitored frequency is recovered to be equal to or lower than the first upper limit value, or
The method for controlling an uninterruptible power supply device, wherein the charging operation and the active filter operation are restarted after a predetermined time period has elapsed after recovering to the lower limit value or more. 2. When the commercial power source is healthy, power is supplied to the load through a semiconductor switch that supplies / shuts off the power from the commercial power source, and the inverter operates to charge the commercial battery from the commercial power source and generate the load. In the control method of the uninterruptible power supply device that performs the active filter operation that absorbs the harmonic current and the reactive current, and during the power failure of the commercial power supply, the power is supplied to the load from the storage battery via the inverter. When the monitored frequency exceeds the first upper limit value, or
When the value is below the lower limit value of the above, the charging operation and the active filter operation are stopped, and the monitored frequency is recovered to be equal to or lower than the second upper limit value which is lower than the first upper limit value, or the second frequency higher than the first lower limit value. A control method of an uninterruptible power supply device, characterized in that the charging operation and the active filter operation are restarted when the value is recovered to be equal to or higher than a lower limit value. 3. When the commercial power source is healthy, power is supplied to the load through a semiconductor switch that supplies / shuts off the power from the commercial power source, and the inverter operates to charge the storage battery from the commercial power source and generate from the load. In a control method of an uninterruptible power supply device, which performs an active filter operation for absorbing a harmonic current or a reactive current, and supplies power to a load from a storage battery via an inverter during a power failure of a commercial power supply, a semiconductor constituting the inverter. When the case temperature of the switch element is detected, and when the detected case temperature exceeds the first set temperature, the active filter operation is suppressed within the range of the capacity smaller than the rated compensation capacity, and the detected case temperature is the first An uninterruptible power supply characterized by stopping the active filter operation when a second set temperature higher than the set temperature is exceeded. Method of controlling the source apparatus. 4. When the commercial power source is healthy, power is supplied to the load through a semiconductor switch that supplies / shuts off the power from the commercial power source, and the inverter operates to charge the commercial battery from the commercial power source and generate from the load. In the control method of an uninterruptible power supply device that performs active filter operation that absorbs harmonic current and reactive current, and supplies power to the load from the storage battery through the inverter when the commercial power supply fails, While monitoring the terminal voltage of the storage battery, the semiconductor switch is cut off for a predetermined period to supply power to the load from the storage battery via the inverter, and the terminal voltage of the storage battery is set to the first set value within the predetermined period. When the following is reached or when the predetermined period is reached and the second set value is higher than the first set value and is equal to or less than this, this is displayed externally, When the period is reached, or when the terminal voltage of the storage battery becomes equal to or lower than a first set value, the semiconductor switch is re-conducted, and power is supplied to the load from a commercial power source. Control method.