JP2001242946A - Variable load device and its use method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a simulated load device of a generator switchable of the capacity with multiple sizes. SOLUTION: A variable load device 10 to be used as the simulated load device of a generator 12 supplies electric power to a load part 13 through an ac power regulator 14. Inside of the ac power regulator 14, switching elements such as IGBT are included and control PWM at a control part 11. The electric power to be calculated based on the measurement results of both electric current and voltage by an operation part 17 is controlled so as to correspond to the capacity given by an external input signal terminal 18. Through alteration of input capacitance value from the outside, capacity of load can be easily changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a variable load device capable of changing power capacity and a method of using the same.

[0002]

2. Description of the Related Art Conventionally, a simulated load device 1 as shown in FIG. 8 has been used for testing a generator 2 and the like.
The generator 2 supplies power to a load 3 including a plurality of consumers A, B,..., Z in an actual use state. For this purpose, the simulated load 1 is used. The simulated load 1 is, for example, a resistor, and consumes electric power according to the capacity of the generator 2. The consumed power is dissipated into the atmosphere as heat.
When the capacity of the simulated load 1 is increased, the amount of generated heat is also increased, so that the simulated load device 1 is also increased in size. The simulated load device 1 is a resistor, and the resistance value is determined according to the output voltage of the generator 2 and the rated power. Therefore, in the simulated load device 1 using a simple resistor, it is difficult to use the simulated load device 2 when the capacity of the generator 2 is different.
Simulated load devices 1 corresponding to the capacity of the generator 2 must be prepared one by one. In various load states, the generator 2
In order to perform the above test, the simulated load devices 1 having different capacities must be prepared.

FIG. 9 shows a schematic configuration of a simulated load device 5 capable of changing the capacity. In the simulated load device 5, the phase of the thyristor circuit 6 is controlled so that power is supplied to the resistor 8 at the phase angle set by the phase angle setting circuit 7. For example, it is assumed that 100 A power is supplied to a load at 100 V. That is, the resistor 8
It should have a capacity of 0 V × 100 A = 10 kW and could be used as a load for testing a 10 kW generator 1. When testing the 10 kW generator 2 with the thyristor-type simulated load device 5, the load capacity is desirably 10 kW or less. This is because, as described later, in the thyristor method, a load greater than the capacity of the generator 2 may be momentarily applied, and both the voltage and the frequency of the generator 2 may be reduced. Therefore, when testing the generator 2, usually, the simulated load device 1 having a capacity equal to or less than the capacity of the generator 2 is used even if the capacity is variable by the thyristor method. In addition, in testing a plurality of types of generators 2, it is necessary to use loads of a plurality of capacities. For this reason,
A plurality of thyristor-type simulated load devices 5 must be prepared corresponding to a plurality of capacities.

FIG. 10 shows the principle that the thyristor-type simulated load device 5 shown in FIG. 9 can change the load capacity. The thyristor circuit 6 cuts off the load current during a period corresponding to the phase angle set by the phase angle setting circuit 7 of all the waveforms of the AC power, and turns on the thyristor after a period corresponding to the phase angle elapses. A load current is supplied to the resistor 8 as indicated by a solid color. For example, when the phase angle α is 90 degrees, the load current flows by half of the sine wave from 0 degrees to 180 degrees. If the phase angle α is further increased, the period during which the load current flows becomes shorter, and the capacity can be reduced. If the phase angle α is made smaller, the period during which the load current flows becomes longer, and the capacity can be increased.

[0005]

The thyristor type simulated load device 5 as shown in FIG. 9 can realize a plurality of load capacities by one unit by controlling the phase of the thyristor circuit 6. However, for example, as shown in FIG. 10 for the case of α = 90 degrees, even if the load current flows in half, the load capacity is twice that of the generator 2 so that the load current for 180 degrees can be supplied. Required. in this way,
The thyristor-type simulated load device 5 as shown in FIG. 9 has a problem with the power supply capacity even if it seems that a large-capacity load can simulate a small capacity. Simulating continuous load changes for testing capacity generators is virtually impossible.

A simulated load device 1 as shown in FIG.
A method is also conceivable in which zero load resistors are built in and the capacitance of the load resistors is changed stepwise by turning on / off the corresponding switches. However, in such a method, the load changes gradually, and it is impossible to simulate a fine load change.

Further, the simulated load device 1 shown in FIG.
The thyristor-type simulated load device 5 shown in FIG. 1 is used only for testing the generator 2. For this reason, demand is limited, and it is difficult to achieve cost cut down by mass production.

It is an object of the present invention to provide a variable load device capable of simulating a load in various states and a method of using the same.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a switching device provided between an AC power supply and a resistor, which is a load for an AC power supply, and capable of switching power supplied from the AC power supply to the resistor. An element, power measuring means for measuring power supplied from the AC power supply to the resistor via the switching element, capacity setting means for setting a load capacity, and a resistor from the AC power supply measured by the power measuring means. And a control means for performing PWM control on the switching element so that the power supplied to the switching element coincides with the capacity set in the capacity setting means.

According to the present invention, a switching element is provided between the AC power supply and the resistor serving as a load, and PWM control is performed by the control means. The control unit controls the switching element based on the measurement result of the measurement unit such that the power having the capacitance value set in the capacitance setting unit is supplied to the resistor. Power adjustment by switching element is PWM
Since the control is performed, the capacities of the load side and the power supply side can be made the same, and the capacity of the load can be changed within a range having the upper limit of the power capacity of the resistor.

Further, the present invention provides a resistor serving as a load of an AC power supply, a switching element provided between the AC power supply and the resistor and capable of switching power supplied from the AC power supply to the resistor, Power measuring means for measuring the power supplied to the resistor from the switching element through,
PWM control of the switching element so that the power supplied to the resistor from the AC power supply measured by the power measuring means matches the capacity set in the capacity setting means. A variable load device including a control unit for performing a test of the power supply device.

According to the present invention, the power consumed by the resistor can be changed by the PWM control by the switching element to change the capacity of the load. Therefore, when used as a simulated load such as a generator, A small-capacity load can be easily realized without increasing the required power supply capacity.

Further, the present invention provides a resistor serving as a load of an AC power supply, a switching element provided between the AC power supply and the resistor and capable of switching power supplied from the AC power supply to the resistor, Power measuring means for measuring the power supplied to the resistor from the switching element through,
PWM control of the switching element so that the power supplied to the resistor from the AC power supply measured by the power measuring means matches the capacity set in the capacity setting means. A method of using a variable load device, comprising: using a variable load device including control means for performing a reverse tide when using a commercial power system and a private power generation facility together.

According to the present invention, the variable load device can easily change the power consumed by the resistor according to the capacity set in the capacity setting means by PWM control of the switching element. When such a variable load device is used in combination with the commercial power system and the private power generation facility, and when the power from the private power generation facility becomes excessive and a reverse power flow that flows to the commercial power system side is about to occur, It is possible to increase the load capacity, absorb excess power, and effectively prevent reverse power flow.

[0015]

FIG. 1 shows a schematic configuration of a variable load device 10 as one embodiment of the present invention. The variable load device 10 has a capacity set by the control unit 11,
It can be used as a simulated load device for the generator 12. In the variable load device 10, in addition to the control unit 11, a load unit 13 as a resistor, an AC power regulator 14, a current transformer 15 for detecting load current, and a transformer 16 for detecting load voltage. And a calculation unit 17 that performs current measurement and voltage measurement based on detection outputs from the current transformer 15 and the transformer 16 and calculates a power value as a product of the voltage and the current. The control unit 11 compares the power value calculated by the calculation unit 17 with a capacitance value given from an external computer device or the like via the external input signal terminal 18, and
An input signal for controlling the AC power regulator 14 is provided so that the power value calculated in step (b) matches the externally input capacity value.

FIG. 2 shows the internal configuration of the AC power regulator 14 shown in FIG. The PWM control circuit 20 is a switching element, and is an insulated gate bipolar transistor (In
IGBT2 which is sulated Gate Bipolar Transistor)
The gate electrodes 1, 22, 23, 24, 25, and 26 are driven to perform pulse width modulation (PWM) control of the power supplied to the load 13. A command for the PWM control circuit 20 to perform control is given from the control unit 11 in FIG. Although simplified in FIG. 1 for convenience of explanation, the variable load device 10 of the present embodiment is a variable load with respect to three-phase AC power composed of U, V, and W phases. A pair of IGBs is provided between the load 13 and the three-phase AC power supplies U, V, and W phases.
T21, 22; 23, 24; 25, 26 intervene, and perform switching control of the load current supplied to the load 13 by PWM. In this embodiment, IGB is used as the switching element.
Since T21 to T26 are used, switching can be performed at high speed and the load can be varied efficiently. Note that another element such as a gate turn-on thyristor (GTO) can be used as the switching element. Similar effects can be obtained by switching in two phases instead of switching in all three phases.

FIG. 3 shows a PWM control as shown in FIG.
Indicates that the load capacity does not increase with respect to the power supply side. P
In the WM control, if a current of 100 A is supplied to the load 13 at a voltage of 100 V and the voltage of the power supply is 200 V, the current on the power supply side is 50 A, which indicates that the load 13 has a transformer action. I have. That is, PWM
By performing the control, unlike the thyristor method as shown in FIG. 9, the current on the power supply side is a current obtained by converting the capacity into a voltage, and the current can be reduced when the voltage on the power supply side is higher than the load side. It is very different in point.

FIG. 4 shows a simulated load device 1 as shown in FIG.
Is switched to a plurality of capacities by a switch in FIG.
A case where the capacity is continuously changed using the PWM control as in the present embodiment is shown in comparison in FIG. In the switch switching type as shown in FIG. 1A, the magnitude of the load can be switched based on an external input signal, but the output can be changed only in steps. When a mechanical switch is used, the switching speed is reduced. If switching is performed using a switching element such as a thyristor, the switching speed can be increased, but
If you try to reduce the steps and increase the number of switching steps,
Many switching elements are required. As shown in (b), if the PWM control is used, a continuous output change is possible, and it is possible to avoid a stepwise load change as shown in (a).

FIG. 5A shows a case where the phase control is performed by one of the three-phase alternating currents by the thyristor circuit 6 as shown in FIG. 9, and a case where the PWM control as in the present embodiment is performed. (B). In the case of phase control using a thyristor, there is a portion where the voltage (current) rises sharply, and the waveform includes harmonics. When the thyristor conducts in another phase, the effect appears on the opposite polarity side. On the other hand, in the PWM control shown in (b), switching is repeated at a cycle very short as compared with the frequency of the AC power supply, smoothed by the inductance and the reactance of the electric wire, and the waveform hardly contains harmonics. Power supply voltage waveform. For example, the switching frequency is 16
It is about kHz.

In general, there is a demand for suppression of harmonic current generated by using electric equipment. Ministry of International Trade and Industry
The Agency for Natural Resources and Energy announced on May 26, 1994, based on the results of a study by the Subcommittee on Harmonics of the Electrical Appliances Research Committee of the Japan Electric Association, Guidelines for Measures to Suppress Harmonics for Consumers Receiving High Voltage or Extra High Voltage. These guidelines apply to voltage-type PWM control and current-type P
In a self-excited three-phase bridge circuit and a self-excited single-phase bridge circuit using WM control, the conversion coefficient K is 0, and the equivalent capacity as a harmonic generation device is 0, indicating that the device can be regarded as a device that does not generate harmonics. Have been. As described above, in the case of the PWM control, the voltage (current) continuously changes, and no harmonic is generated. Therefore, no harmonic countermeasures are required. Table 1 below
Shows extracted portions of the self-excited single-phase bridge and the AC power regulator using the thyristor method in the harmonic guidelines.

[0021]

[Table 1]

FIG. 6 shows a comparison between the input and output waveforms of the current and voltage between the thyristor type simulated load device shown in FIG. 8 and the variable load device 10 of the present embodiment. FIG. 6A shows the phase control by the thyristor.
Shows the input waveform. The thin solid line shows the waveform of the input voltage Vin, and the thick solid line shows the waveform of the input current Iin. Although the input voltage Vin has a sinusoidal waveform, the input current Iin
Is a waveform which rises rapidly after being delayed by the set phase angle. As shown in FIG. 6B, the output voltage Vout
And the waveform of the output current Iout is the input current Iout shown in FIG.
In response to the waveform of “in”, the waveform suddenly rises after being delayed by the set phase angle. In such thyristor control, the power supplied to the load is reduced when integrated over one cycle, but is instantaneously increased. For this reason, the capacity of the power source requires a larger capacity as the rated capacity of the load is set at a place where the phase angle is larger. Assuming that the rated current is obtained when the phase angle is 90 degrees, the power supply capacity is required to be twice the load capacity.

FIG. 6C shows an input waveform in the case of PWM control. The thin solid line shows the waveform of the input voltage Vin, and the thick solid line shows the waveform of the input current Iin. In the PWM control, the waveform of the input voltage Vin does not change, and the amplitude of the input current Iin changes according to the load capacity. FIG. 6D shows P
7 shows an output waveform in the case of WM control. In the output waveform, although the amplitudes of the output voltage Vout and the output current Iout change according to the load capacitance, the waveform does not change. That is, in the case of the PWM control, since the power is directly adjusted, the input current Iin flowing from the power supply is a current converted into the power supply voltage Vin in capacity even when the rated current of the load is obtained at a low output voltage Vout.

FIG. 7 shows the configuration of another embodiment of the present invention. In the present embodiment, the variable load device 10 shown in FIG.
Is used to prevent reverse tide when the commercial power system 30 and the private power generation facility 31 are used together. By using the commercial power system 30 and the private power generation facility 31 together, a highly reliable power supply can be performed.
And the power generation amount of the private power generation facility 31
May be larger than the amount of power used. If the amount of power generated by the private power generation facility 31 becomes excessive, there is a possibility that it will flow out to the commercial power system 30 side. Such a reverse power flow is not desirable for the commercial power system 30 and must be carefully avoided. When the variable load device 10 of the present embodiment is connected and the generated power from the private power generation facility 30 becomes excessive, the excess power can be consumed to prevent reverse power flow. For example, data indicating the excess power of the private power generation equipment 30 is input to the control unit 11 of FIG. The control can be performed by absorbing the excess. Alternatively, the power to be discharged to the commercial power system 30 may be directly measured, and the power may be fed back to the control unit 11 so that the power becomes zero, thereby preventing the reverse power flow.

[0025]

As described above, according to the present invention, the power supplied from the AC power supply to the load is supplied to the PWM of the switching element.
By the control, control can be performed so as to match the value set in the capacity setting means, so that a large load capacity can be realized with one variable load device. Since the change of the load capacity is performed by the PWM control of the switching element, there is no problem that the capacity is substantially increased as in the case of the phase angle control by the thyristor, and the load capacity can be easily changed.

Further, according to the present invention, a variable load device whose load capacity can be changed by PWM control is used as a simulated load device used for testing a power generation facility such as a generator. A small-capacity load can be realized without requiring a large increase in power capacity. Further, since the load capacity can be changed in accordance with the value set in the capacity setting means, it is possible to set various patterns of the change in the load demand of the power generation equipment and perform the test of the power generation equipment.

Further, according to the present invention, a variable load device capable of easily changing the load capacity by the PWM control is used for preventing reverse tide when the commercial power system and the private power generation facility are used in combination. When the power generation capacity of the power generation equipment increases and a reverse tide is about to occur, the load capacity of the variable load device is increased to absorb excess power, and the reverse power flow can be effectively prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic electrical configuration of a variable load device 10 according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of the AC power regulator 14 of FIG.

FIG. 3 is a diagram showing the relationship between the power capacity on the load side and the power capacity on the power supply side in this embodiment.

FIG. 4 is a graph showing a comparison between a change in capacitance due to conventional multi-stage switching and a change in capacitance according to the present embodiment.

FIG. 5 is a graph showing a state in which harmonics are improved in a voltage waveform by the PWM control according to the present embodiment as compared with a voltage waveform by the conventional thyristor control.

FIG. 6 is a graph showing a comparison between input and output waveforms in the case of conventional thyristor control and input and output waveforms of the PWM control of the present embodiment.

FIG. 7 is a block diagram showing an example in which the variable load device 10 shown in FIG. 1 is used for reverse tide prevention as another embodiment of the present invention.

FIG. 8 is a simplified block diagram showing a state in which a generator is tested using a simulated load device.

FIG. 9 is a block diagram showing a configuration in which the load capacity is made variable using phase control by a thyristor in the simulated load device.

FIG. 10 is a waveform diagram showing a state in which the load capacity is changed by phase control in the simulated load device of FIG. 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Variable load apparatus 11 Control part 12 Generator 13 Load part 14 AC power regulator 17 Operation part 18 External input signal terminal 20 PWM control circuit 21-26 IGBT 30 Commercial power system 31 Private power generation equipment

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yuji Nakai 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka Inside Osaka Gas Co., Ltd. (72) Kozo Yamamuro 4-chome, Hirano-cho, Chuo-ku, Osaka, Osaka No. 1-2 Inside Osaka Gas Co., Ltd. (72) Inventor Hiroyuki Omi 6-3-2 Ebie, Fukushima-ku, Osaka City, Osaka Prefecture Inside Thermoelectric Industry Co., Ltd. (72) Inventor Seiji Tanaka 2-chome Wakabadai, Nara City, Nara Prefecture No. 18 (72) Inventor Hironori Nagamatsu 21-9 Shimojima-cho, Kadoma-shi, Osaka F-term (reference) 5H410 BB05 CC03 DD02 DD03 DD07 EA10 EA35 EB09 EB40 FF03 FF05 FF24 GG00

Claims (3)

[Claims] And a switching element provided between the AC power supply and the resistor and capable of switching power supplied from the AC power supply to the resistor, and a switching element provided from the AC power supply. Power measuring means for measuring the power supplied to the resistor via the capacitor, capacity setting means for setting the load capacity, and the power supplied to the resistor from the AC power supply measured by the power measuring means, Control means for performing PWM control on the switching element so as to match the capacity set in the setting means. 2. A resistor provided as a load of an AC power supply, a switching element provided between the AC power supply and the resistor, capable of switching power supplied from the AC power supply to the resistor, and a switching element provided from the AC power supply. Power measuring means for measuring the power supplied to the resistor via the capacitor, capacity setting means for setting the load capacity, and the power supplied to the resistor from the AC power supply measured by the power measuring means, A variable load device comprising: a variable load device including PWM control of a switching element so as to match a capacity set in a setting device, as a simulated load for testing a power supply device. How to use 3. A resistor provided as a load of an AC power supply, a switching element provided between the AC power supply and the resistor, capable of switching power supplied from the AC power supply to the resistor, and a switching element provided from the AC power supply. Power measuring means for measuring the power supplied to the resistor via the capacitor, capacity setting means for setting the load capacity, and the power supplied to the resistor from the AC power supply measured by the power measuring means, A variable load device including control means for performing PWM control of the switching element so as to match the capacity set in the setting means is used for reverse tide prevention when using both a commercial power system and a private power generation facility. The use of the variable load device characterized by the above-mentioned.