JP3432308B2 - Harmonic current / voltage monitoring / alarm device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a harmonic current / voltage monitor / alarm device used in power receiving equipment and the like.

[0002]

2. Description of the Related Art With the recent spread of harmonic generating loads such as inverters, the voltage distortion of the power distribution system has increased, and the damage to power equipment due to harmonics has increased. There are many cases in which phase-advancing capacitor equipment is subject to obstacles, and due to the increase in the inflow of harmonic currents into the phase-advancing capacitor circuit, cases such as overheating / burning of the series reactor and dielectric breakdown of the capacitor are increasing.

As one of the measures against the above, a current distortion rate or a harmonic current component of a phase advancing capacitor circuit is detected and monitored, and when an overload occurs, an alarm is issued and the phase advancing capacitor facility is opened. Is being done.

Further, in order to suppress the outflow amount of the harmonic current from the load generating the harmonics to the power supply side, the current of the power converter such as the inverter is monitored to be equal to or more than a value that adversely affects other devices. When a harmonic current is generated, it is also stopped.

[0005]

In the above-mentioned prior art, if the phase advancing capacitor circuit is opened or the power converter is stopped by the operation of the harmonic current monitoring alarm device, the subsequent current detection is impossible. Therefore, there is a drawback that it is not possible to judge whether or not to restart or restart the operation after that.

FIG. 3 shows an example in which a harmonic current monitoring alarm device is applied to a conventional phase advancing capacitor circuit. In the figure, 11 is a phase advancing capacitor, 12 is a series reactor, 6 is a switch, and 30 is a switch. This is a harmonic current monitoring and alarm device. This device detects the current in the phase advancing capacitor circuit by the current transformer 4 for the instrument, and when the harmonic current amount increases and the phase advancing capacitor circuit becomes overloaded, an alarm is issued. A control signal is issued to open the switch 6.

In the above device, when the switch is opened due to the operation of the harmonic current monitoring and warning device, the current in the phase advance capacitor circuit becomes zero, and the subsequent harmonic condition cannot be monitored. Therefore, whether or not the switch 6 can be turned on again causes a problem that must be left to a human judgment.

In addition to the above-mentioned current detection, the voltage distortion of the bus bar 2 is measured and monitored, and when the voltage distortion exceeds a value that adversely affects other equipment, the switch is opened to stop the circuit equipment and If the strain becomes less than this value, there is also a method to restore the operation by reclosing the switch, but the relationship between the allowable current and the voltage strain differs depending on the rating and characteristics of the load equipment, and it is difficult to predict accurately. Yes, it cannot be a reliable monitoring and alarm device.

[0009]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and provides a harmonic current / voltage monitoring and alarming device which is reliable in operation and is capable of automatically returning a circuit. Is.

That is, from the instrument current transformer 4 of the load circuit and the instrument transformer 3 of the bus 2 to which the load circuit is connected,
The current and the voltage are taken in, and the current measuring unit 51 and the voltage measuring unit 50 measure the current distortion and the voltage distortion, respectively, and the harmonic current distortion rate or the harmonic current value is set in advance in the current setting unit 56. When the distortion rate or the harmonic current value is compared with the current comparison section 53A, and this set value is exceeded, the contact operation section 58 causes the contact holding section 59 to operate the contact of the closing device 6 to open the circuit, Hold this.

The voltage distortion (harmonic voltage distortion rate or harmonic voltage value) at the time of contact operation described above is stored in the voltage storage unit 54, and the value at which the load of voltage distortion can be restored is stored as a voltage based on this voltage distortion. The voltage distortion measurement value is set by the setting unit 55, and the voltage distortion measurement value is compared with this voltage distortion setting value by the voltage comparing unit 53B. If the voltage distortion becomes equal to or less than the recoverable setting value of this load, the above contact holding is released. By doing so, a function to automatically restore the load is provided.

By using the harmonic current / voltage monitoring alarm device 5 having such a function, when the load is a phase-advancing capacitor facility, the harmonic current distortion rate or the harmonic current value set in the current setting section is used. If the value exceeds the limit, the operation of this device prevents the series reactor and the capacitor from being overheated, burnt out, and causes dielectric breakdown. If the bus voltage distortion is reduced to a satisfactory level, the power can be automatically turned on again.

In the case of a power converter in which the load generates harmonics, if the current distortion exceeds the harmonic current distortion rate or the harmonic current value set in the current setting section, the operation of this device will cause a shutdown or The output is reduced to prevent an excessive harmonic current from flowing out to the power supply side, thereby preventing an excessive increase in voltage distortion of the bus bar. If the bus voltage distortion drops to a level that does not cause a problem, automatic restart is possible.

As the current distortion and the voltage distortion, it is convenient to use the current distortion rate and the voltage distortion rate for those in which the fundamental wave current does not largely change, such as a phase advancing capacitor. It is preferable to use the total current distortion rate and the total voltage distortion rate. However, if resonance at a specific harmonic order is a concern, it may be better to use the distortion rate at the specific harmonic order. Further, in devices and equipment including power converters, the fundamental wave current fluctuates depending on the load, so it is rational to manage the flowing out harmonic current based on the absolute value of the harmonic current. The harmonic current value is preferably used as the current distortion.

[0015]

As described above, the harmonic current / voltage monitoring alarm device of the present invention operates when the current distortion of the load equipment exceeds the harmonic current distortion rate or the harmonic current value set in the current setting section, If the load equipment is opened or stopped and the voltage distortion of the bus bar to which the above load equipment is connected falls below a certain percentage below the value during the above operation, the contacts will be restored and the power will be automatically re-applied to the above load. It has a function of restarting the operation of the equipment.

[0016]

Embodiment 1 An embodiment of the present invention will be described with reference to FIGS. FIG. 1 (A) shows an embodiment of the present invention in a phase advancing capacitor equipment, 11 is a phase advancing capacitor, 12 is a series reactor, 6 is a switch, 5 is a harmonic current / voltage monitoring alarm device of the present invention, 3 Is an instrument transformer and 4 is an instrument current transformer.

FIG. 2 is an internal block diagram of the harmonic current / voltage monitoring and alarm device 5 of the present invention, in which the secondary current of the instrument current transformer 4 is input to the current measuring section 51 to cause current distortion. (Harmonic current distortion rate or harmonic current value) is constantly measured, and the value preset by the current setting unit 56 and the current comparison unit 5
3A, when the current distortion exceeds the set value, a signal is sent to the contact operation unit 58, and the contact operation unit 58 causes the contact holding unit 59 to operate the contact of the switch 6. Circuit to open the circuit and hold it.

The secondary voltage of the voltage transformer 3 is the voltage measuring unit 5
0, the voltage distortion (harmonic voltage distortion rate or harmonic voltage value) is constantly measured, and the voltage distortion at the time of the contact operation is stored in the voltage storage unit 54. Here, the voltage distortion has a constant ratio ( A value obtained by multiplying by 50%) is set by the voltage setting unit 55. The voltage distortion set value and the voltage distortion constantly measured by the voltage measuring unit 50 are compared by the voltage comparison unit 53B, and when the voltage distortion is reduced to the voltage distortion set value or less, a signal is released from the contact holding unit 57. Then, the contacts of the switch 6 are returned to the initial state. The values of the current distortion and the voltage distortion measured in real time can be displayed and monitored on the respective voltage / current display sections 52.

As described above, by the series of operations of the harmonic current / voltage monitoring device, the phase advancing capacitor is opened by this contact signal when the current distortion exceeds the set limit, and the voltage distortion is more constant than during this operation. If it decreases at a rate of, it can be re-closed by restoring the contact.

In this case, the distortion factor may be used as the current distortion and the voltage distortion, or the harmonic current value and the harmonic voltage value may be used as the absolute values. Further, as the distortion rate, the harmonic current value, and the harmonic voltage value, only specific orders may be used, or the total distortion rate, the harmonic combined current value, and the harmonic combined voltage value may be used.

[0021]

[Embodiment 2] FIG. 1B shows an embodiment of the present invention in the case where a load having equipment or equipment 21 including a power converter for generating harmonics such as an inverter is connected to a bus bar.

In FIG. 1B, 21 is a load having a power converter such as a thyristor, 22 is a gate block circuit, and other circuit configurations are the same as those in the first embodiment.

That is, the output signal of the harmonic current / voltage monitoring alarm device 5 is transmitted to the gate block circuit 22,
Turn on / off the gate signal circuit of power converters such as thyristors
0FF is performed to stop the load and control the operation. Example 1
Similarly, when the current distortion (in this case, the harmonic current value) exceeds the harmonic current value set in the current setting unit, a signal is transmitted to the gate block circuit 22 to stop the operation of the power converter 21, If the voltage distortion falls below a certain ratio below the value during the operation, the gate block is released and the operation of the load can be restarted.

[0024]

As described above, according to the present invention, it is possible to detect the current distortion of the load equipment such as the phase advancing capacitor equipment and the power converter, and to surely open or stop the load at the set limit value. At the same time, when the bus voltage distortion at this time drops below a certain rate, the load can be automatically restarted or restarted, so that reliable harmonic interference prevention or excessive harmonic current can be prevented. Can be prevented.

Compared with conventional monitoring of harmonic current only,
It will be possible to perform restarting and restarting reliably, and it will be possible to more reliably prevent harmonic interference of power equipment compared to monitoring only harmonic voltage, which will be of great industrial and practical value. is there.

[Brief description of drawings]

FIG. 1A is a circuit configuration diagram of a phase advancing capacitor circuit according to a first embodiment of the present invention. Figure 1 (B)
It is a circuit block diagram of the load circuit which has a power converter, such as a thyristor, of Example 2 of this invention.

FIG. 2 is an internal configuration diagram of a harmonic current / voltage monitoring alarm device of the present invention.

FIG. 3 is an example of an application circuit of a conventional harmonic current monitoring and warning device.

[Explanation of symbols]

2, bus 3, voltage transformer 4, current transformer for instrument 5. Harmonic current / voltage monitoring alarm device 6, switch 11, phase-advancing capacitor 12, series reactor 21, a load having a power converter including a thyristor 22, gate block circuit 30, harmonic current monitoring alarm device 50, voltage measuring unit 51, current measuring unit 52, voltage / current display 53A, current comparison unit 53B, voltage comparison unit 54, voltage storage unit 55, voltage setting section 56, current setting section 57, contact holding release section 58, contact operation unit 59, contact holder T1, voltage input terminal T2, current input terminal T3, control signal output end

Front page continuation (72) Kenji Morisada Kenji Morisada Kenji Oike Dori Karasuma Higashiiri Ichidori Nakagyo-ku, Kyoto Prefecture 4 Uehara Building, 3rd floor, Nichicon Co., 191, Nakabori-cho, Nichicon Co., Ltd. JP, A) JP 57-177225 (JP, A) JP 5-49171 (JP, A) JP 6-217451 (JP, A) JP 3-82326 (JP, A) JP Hei 5-268718 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02H 3/50-3/52 H02H 3/00-3/07

Claims (3)

(57) [Claims] 1. A load connected to a bus bar (2) is a phase-advancing capacitor facility (11, 12) or a facility or device (21) including a power converter that generates a harmonic current, for a meter A current transformer (4) and an instrument transformer (3),
A harmonic current / voltage monitoring alarm device used in a system comprising a harmonic current / voltage monitoring alarm device (5) and a switch (6), wherein the load is a busbar (2 ) Switch (6)
Connected through the current transformer and has a current transformer (4) for measuring the load current and a transformer (3) for measuring the bus voltage, and the harmonic current / voltage monitoring alarm device (5) is Current and voltage are taken into the current measuring unit (51) and voltage measuring unit (50) from the instrument current transformer (4) and the instrument transformer (3), and the current distortion rate of the load current and the voltage distortion of the bus voltage are taken. The current distortion rate is measured, the current distortion rate is compared with a limit value preset in the current setting section (56) by the current comparison section (53A), and if the set limit value is exceeded, the contact operation section (58) that operates. And a voltage holding unit (59) for holding the operated signal contact, and for storing the bus voltage distortion rate at the time of the contact operation, and a limit value of the voltage distortion rate by this stored voltage. And a voltage setting section (55) for automatically setting the setting limit value and the bus voltage. The voltage comparison unit (53B) compares the voltage distortion rates of the above, and when the bus voltage distortion rate is less than or equal to this set limit value, it has a contact holding release section (57) for releasing the above-mentioned contact holding. Harmonic current / voltage monitoring alarm device. 2. The current distortion rate is a current total distortion rate or a current distortion rate of a preset specific harmonic order, and the voltage distortion rate is a voltage total distortion rate or a preset specific harmonic order. The harmonic current / voltage monitoring and alarm device according to claim 1, wherein the voltage distortion factor is 3. A harmonic composite current value or a harmonic current value of a preset specific harmonic order is used instead of the current distortion rate, and a harmonic composite voltage value or a harmonic composite voltage value is used instead of the voltage / voltage distortion rate. 2. The harmonic current / voltage monitoring alarm device according to claim 1, wherein a preset harmonic voltage value of a specific harmonic order is used.