JP2001145265A - Automatic power factor controlling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve an automatic power factor controlling device that is capable of many capacity combinations as a capacitor group to be controlled, is capable of accurately controlling a number of capacitors, and is inexpensive. SOLUTION: Control for connecting each capacitor to a power distribution line 4 successively and individually for fixed time and then separating it is made when an operation is started by an automatic switching command part 17, the amount of change in the reactive power of the power distribution line 4 when connecting and disconnecting each capacitor 23 is detected by a reactive power detection part 13 at that time, the average value of the absolute value of the amount of change in the reactive power when connecting and disconnecting each capacitor 23 is obtained for each capacitor 23, and each average value is stored at a capacitor reactive power storage part 14 as the reactive power of each capacitor 23. A control part 15 controls the connection and disconnection to and from the power distribution line 4 of each capacitor 23 according to the reactive power of the power distribution line 4 being detected by the reactive power detection part 13 based on the reactive power of each capacitor 23 that has been stored.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic power factor control device for a phase-advanced capacitor equipment.

[0002]

2. Description of the Related Art An automatic power factor control device for a phase-advancing capacitor
This is a device that keeps the power factor at the installation point constant in combination with the capacitor equipment.

A conventional automatic power factor control device for a phase advance capacitor will be described below. FIG. 7 is a block diagram showing a configuration of a conventional automatic power factor control device. 1 is a conventional automatic power factor control device, 2 is a control capacitor group, 3 is a load, 4 is a distribution line, 5 is an instrument transformer, and 6 is a current transformer. 21 is a switch, 22 is a series reactor, and 23 is a phase advance capacitor. 51 is a voltage detection unit, 52 is a current detection unit, 53 is a reactive power detection unit, 54 is a capacitor reactive power setting storage unit, 5
5 is a control unit, and 56 is an output unit.

The conventional automatic power factor control device 1 includes a capacitor reactive power setting storage unit 54 for setting and storing the reactive power of each of the capacitors 23 of the control capacitor group 2, and a control unit 5 for controlling the distribution line 4 via the instrument transformer 5. A voltage detector 51 for detecting a voltage, a current detector 52 for detecting a current of the distribution line 4 via the current transformer 6, a voltage detector 51 and a current detector 52
Reactive power detection unit 53 for detecting reactive power from the voltage and current detected by
A control unit 55 that controls opening and closing of each switch 21 of the control capacitor group 2 based on the reactive power of the capacitor set and stored in 4 and the reactive power detected by the reactive power detection unit 53;
An output unit 56 that receives a control signal from the control unit 55 and outputs an opening / closing signal corresponding to the control signal to the outside. Output unit 5
The switches 21 of the control capacitor group 2 are opened / closed by the opening / closing signal from the switch 6.

FIG. 8 is a diagram showing an example of the operation of the conventional automatic power factor control device 1. As shown in FIG. Hereinafter, closing the switch 21 and connecting the capacitor 23 to the distribution line 4 is referred to as turning on the capacitor 23. Conversely, opening the switch 21 and disconnecting the capacitor 23 from the distribution line 4 is referred to as capacitor 23.
Say to open. In FIG. 8, the solid line indicates the operation when the capacitor is turned on, and the broken line indicates the operation when the capacitor is opened.

As shown in FIG. 8, the reactive power detected by the reactive power detector 53 is the delayed reactive power, and the delayed reactive power is the reactive power of the capacitor to be controlled next ×
When it becomes larger than k / 2 (k is a coefficient), the capacitor 23 is turned on. Also, the reactive power detected by the reactive power detection unit 53 is the leading reactive power, and the leading reactive power is Reactive power of capacitor to be controlled x k / 2
The control unit 55 performs control so as to open the capacitor 23 when it becomes larger, and keeps the power factor at the installation point constant. The control accuracy improves as the value of k approaches 1. FIG. 8 shows an operation when the capacitors 23 (No. 1 to No. 3) of the control capacitor group 2 have the same capacitance.

[0007]

However, in the above-mentioned conventional configuration, in the case of different capacity control in which the capacitors 23 of the control capacitor group 2 have different capacities, the reactive power of each capacitor 23 is different and the capacitor reactive power setting storage. Since it is necessary to set all the reactive power of each capacitor 23 in the unit 54, in the case of a device for controlling a large number of capacitors, a large number of reactive power setting functions are required. Further, in order to substitute a single setting function, it is necessary to use a capacitor group having an equal capacity or a combination of capacitor groups having a fixed ratio relationship. Therefore, when controlling a large number of capacitors having different capacities, the automatic power factor control device 1 becomes complicated and expensive.
Could not be used.

The capacitor reactive power setting storage unit 54
It is common to use a one-digit digital switch for setting the value to. Therefore, when setting a value such as 250 kvar, the value was rounded off to 3 and input. Therefore, for the control width expressed by the reactive power of the capacitor × k, k
It is necessary to set the value with a margin, and accuracy tends to be lacking.

The present invention solves the conventional problems.
It is an object of the present invention to provide an inexpensive automatic power factor control device that can control any number of capacitors as a group of capacitors to be controlled and that can accurately control a large number of capacitors.

[0010]

SUMMARY OF THE INVENTION An automatic power factor control apparatus according to the present invention includes a circuit reactive power detection section for detecting reactive power of a circuit to which a slow load is connected, and connection of each capacitor of the capacitor group to the circuit. A control unit that controls the disconnection and disconnection based on the reactive power of the electric circuit detected by the electric circuit reactive power detection unit and the reactive power of the controlled capacitor, and connects each capacitor to the electric circuit individually for a certain period of time at the start of operation Automatic opening / closing command section that performs control to disconnect and disconnect, and the amount of change in reactive power of the circuit when connecting and disconnecting each capacitor by the automatic opening / closing command section at the start of operation using the detection value of the circuit reactive power detection section For each capacitor, the average value of the absolute value of the change in reactive power when connected and the absolute value of the change in reactive power when disconnected is determined as the reactive power of each capacitor. It includes support and reactive power calculating unit, and a capacitor reactive power storage unit to be given to the control unit stores the reactive power of the capacitors obtained in the capacitor reactive power calculator.

According to this configuration, at the start of operation, the automatic opening / closing command section controls each capacitor sequentially and individually for a certain period of time to disconnect the capacitor, and at that time, the reactive power of each capacitor is reduced by the capacitor reactive power calculation section. It is not necessary to set the reactive power of the capacitor as in the related art by storing it in the capacitor reactive power storage unit, and it is also necessary to store the accurate capacitor reactive power in the capacitor reactive power storage unit. Can be. As a result, any combination of capacitances is possible as a group of capacitors to be controlled, and a large number of capacitors can be accurately controlled, and an inexpensive automatic power factor control device can be realized.

Further, the control unit controls the capacitor to be connected in order from the one having the lowest reactive power when connecting the capacitor to the electric circuit, and to disconnect the capacitor in order from the one having the large reactive power when disconnecting the capacitor from the electric circuit. , The number of times of connection and disconnection can be reduced, and highly accurate control can be performed.

Further, the capacitor reactive power calculating section also detects the amount of change in the reactive power of the electric circuit when the control section connects and disconnects each capacitor by using the detection value of the electric circuit reactive power detecting section, and operates each capacitor. Calculate the cumulative sum of the absolute values of the changes in the reactive power of the circuit when connecting and disconnecting from the start, count the number of connections and disconnections from the start of operation for each capacitor, and count And the value obtained by dividing the cumulative sum calculated at the time of disconnection by the number of times of connection and disconnection is used as the reactive power of the capacitor, and by rewriting the value of the capacitor reactive power storage unit, more accurate reactive power of the capacitor can be stored. More precise control can be performed.

[0014]

(First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the automatic power factor control device according to the first embodiment of the present invention. In FIG. 1, 2
Denotes a control capacitor group including a plurality of arbitrary phase-advancing capacitors 23, 3 denotes a load (slow-phase load), 4 denotes a distribution line (electric circuit), 5
Is a transformer for an instrument, 6 is a current transformer, 10 is an automatic power factor control device according to the first embodiment, 11 is a voltage detecting unit, 12 is a current detecting unit, 13 is a reactive power detecting unit, and 14 is a capacitor invalid. Power storage unit, 15 is a control unit, 16 is an output unit, 17 is an automatic opening / closing command unit, 21 is a switch, 22 is a serial reactor, 23
Is a phase advance capacitor.

The voltage detecting section 11, the current detecting section 12, and the reactive power detecting section 13 constitute an electric circuit reactive power detecting section for detecting the reactive power of the distribution line 4, which comprises a conventional voltage detecting section 51, a current detecting section 52, It corresponds to the reactive power detection unit 53. However, the reactive power detector 1 according to the present embodiment
Numeral 3 has a function of a capacitor reactive power calculating unit in addition to the function of the conventional reactive power detecting unit 53. That is, the reactive power detection unit 13 includes the conventional reactive power detection unit 53 and the capacitor reactive power calculation unit.

The output section 16 receives a control signal from the control section 15 and a control signal from the automatic opening / closing command section 17 and outputs a corresponding opening / closing signal. It is opened and closed.

The control unit 15 controls connection and disconnection of each of the capacitors 23 of the capacitor group 2 to and from the distribution line 4 by outputting a control signal for controlling the opening and closing of each switch 21. , The reactive power of the distribution line 4 detected by the reactive power detector 13 and the controlled capacitor 23
Based on the reactive power of Here, each capacitor 2
The reactive power value of 3 is obtained from the capacitor reactive power storage unit 14.

When the automatic power factor control device 10 starts operating, the automatic opening / closing command section 17 outputs a control signal for sequentially connecting and disconnecting each capacitor 23 to the distribution line 4 for a certain time.

The capacitor reactive power calculation unit built in the reactive power detection unit 13 uses the reactive power of the distribution line 4 detected by the reactive power detection unit 13 when the automatic power factor control device 10 starts operating, The automatic opening / closing command section 17 detects the amount of change in the reactive power of the distribution line 4 when connecting and disconnecting each capacitor 23, and detects the absolute value of the amount of change in the reactive power when connecting each capacitor 23, and the invalidity when disconnecting. An average value of the absolute value of the power change amount and the average value is obtained, and the average value is used as the reactive power of each capacitor 23 and is provided to the capacitor reactive power storage unit 14.

The capacitor reactive power storage unit 14 stores the value of the supplied reactive power of each capacitor 23.

The operation of the automatic power factor control device 10 at the start of operation will be described with reference to FIG. FIG. 2 is a diagram illustrating a control operation of the automatic opening / closing command unit 17 at the start of operation. In the following description, closing the switch 21 and connecting the capacitor 23 to the distribution line 4 is referred to as turning on the capacitor 23. Conversely, opening the switch 21 and connecting the capacitor 23 to the distribution line 4
The disconnection of the capacitor 23 is called opening the capacitor 23.
The horizontal axis of FIG. 2 indicates each capacitor 23 (No. 1, No. 2,
..) Indicate the times at which they are turned on and off, and the vertical axis indicates the reactive power of each capacitor 23. The operation period of the automatic power factor control device 10 and the operation period of the load 3 are the same.

As shown in FIG. 2, the automatic power factor control device 10
At the start of operation, N
o. After the first capacitor 23 is supplied for a predetermined time, it is opened. Then, after a lapse of a certain time, No. 2 capacitors 2
3 is also charged for a certain period of time and then opened. This operation is performed for all the capacitors 23 in the capacitor group 2.
Here, the time during which each capacitor 23 is turned on,
The interval at which each capacitor 23 is turned on (the time from when one capacitor is opened to when the next capacitor is turned on) is made equal.

In the above operation, the reactive power detector 13
The amount of change in the reactive power when the capacitors 23 are turned on and off is determined, the values of the amounts of change when the capacitors 23 are turned on and when the capacitors 23 are opened are averaged to obtain the reactive power of each capacitor, and stored in the capacitor reactive power storage unit 14. The reason for averaging the values of the amount of change at the time of closing and at the time of opening is to minimize errors. In this way, the reactive power of each capacitor 23 of the capacitor group 2 is accurately measured and stored even if the capacitance is different, without performing operations such as setting in the capacitor reactive power setting storage unit 54 as in the related art. It becomes possible.

Next, FIG. 3 shows a control operation in the present embodiment. In FIG. 3, the solid line indicates the operation when the capacitor is turned on, and the broken line indicates the operation when the capacitor is opened.

As shown in FIG. 3, the control unit 15 controls the distribution line 4 detected by the reactive power detection unit 13 based on the reactive power of each capacitor 23 stored in the capacitor reactive power storage unit 14. Control is performed according to the reactive power. That is,
The reactive power of the distribution line 4 is the delayed reactive power, and the delayed reactive power is the reactive power of the capacitor to be controlled next ×
When it becomes larger than k / 2, the capacitor 23 is turned on. The reactive power of the distribution line 4 is the leading reactive power, and the leading reactive power is the reactive power of the capacitor to be controlled next × k When the value exceeds / 2, a control signal is output so as to open the capacitor 23, and the output unit 16 outputs a switching signal for opening and closing the switch 21 according to the control signal. Here, when the delayed reactive power of the distribution line 4 increases, 1, No. 2, No. 3, ...
, No., when the leading reactive power of the distribution line 4 increases.
3, No. 2, No. The capacitors 23 that are not opened are opened in the order of 1. The number (No.) of the capacitor 23 is for convenience and has no particular meaning.

In the present embodiment, the reactive power of each capacitor 23 is accurately calculated and stored in the capacitor reactive power storage unit 14 at the start of the operation of the automatic power factor control device 10 as described above. With respect to the control width represented by the reactive power × k, the value of the coefficient k can be set to a value closer to 1 than in the related art, and control with higher accuracy can be performed. Note that the coefficient k is a numerical value for determining the control width. Conventionally, about 1.5 was used to prevent hunting, but in the automatic power factor control device 10 of the present embodiment, Since the value measured at the start of operation is used as the reactive power, a value including the tolerance of the system voltage, harmonic content, and capacity can be used. For this reason, even if the coefficient k is about 1.2 to 1.3, hunting can be prevented, and higher-precision control can be performed. As a result, any combination of capacities is possible as the group of capacitors 2 to be controlled.
3 can be controlled accurately. Further, a function for setting the reactive power of each capacitor 23 as in the related art is unnecessary, and
An inexpensive automatic power factor control device can be realized.

In the above description, for the sake of simplicity, the reactive power of each capacitor 23 is stored in the capacitor reactive power storage unit 14. However, the stored reactive power includes the switch 21 and the switch 21. This also includes the amount of the reactive power of the series reactor 22 between the capacitors 23.
The series reactor 22 is provided to suppress the current when the capacitor 23 is turned on and to prevent the harmonics of the distribution line 4 from expanding.

(Second Embodiment) Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a block diagram showing the configuration of the automatic power factor control device according to the second embodiment of the present invention. 4, reference numeral 10 'denotes an automatic power factor control device according to the second embodiment, reference numeral 18 denotes a sort control unit, and other configurations are the same as those in FIG. The control unit according to claim 2 includes a control unit 15 and a sort control unit 18.
It consists of.

The sort control unit 18 grasps the order of smaller or larger values from the values of the reactive power of each capacitor 23 stored in the capacitor reactive power storage unit 14. When the power is turned on, the control unit 15 is instructed on the capacitors to be turned on so as to turn on the capacitors having the lowest reactive power among the capacitors that have not been turned on. Further, when the control unit 15 opens the capacitor 23, the control unit 15 instructs the control unit 15 of a capacitor to be opened such that the capacitor having the largest reactive power is opened from the unopened capacitors. Therefore, the control unit 15 controls turning on / off of the capacitor 23 instructed by the sort control unit 18.

The operation of the automatic power factor control device 10 'of this embodiment at the start of operation is similar to that of the first embodiment, and the reactive power of the capacitor group 2 in this embodiment is also reduced. Assume that it is shown in FIG.

FIG. 5 shows the control operation in the present embodiment. In FIG. 5, the solid line indicates the operation when the capacitor is turned on, and the broken line indicates the operation when the capacitor is opened.

In this embodiment, since the reactive power increases as the load 3 increases, the capacitor group 2 having a different capacity is controlled regardless of the reactive power of each capacitor 23 as in the first embodiment. Instead, the control unit 15 instructs the capacitor 23 to be turned on or off next by the sort control unit 18 on the basis of the value of the reactive power, and changes the designated reactive power value of the capacitor 23 to the capacitor reactive power. Obtained from the storage unit 14 and the reactive power detection unit 1
The control is performed in the same manner as in the first embodiment based on the value detected in step 3.

According to the present embodiment, in addition to the effects of the first embodiment, when the capacitor 23 is turned on, the reactive power is turned on in ascending order of the reactive power, and when the capacitor 23 is opened, the reactive power is turned on from the one having the larger reactive power. By controlling to open in sequence, the number of times of turning on and off the capacitor 23 can be reduced, and highly accurate control can be performed. For example, assuming a constant power factor, the required reactive power increases as the load increases, and decreases as the load decreases, as is clear from FIG. Therefore, when the capacitor 23 is turned on, it is turned on in the order of smaller reactive power, and when the capacitor 23 is opened, it is opened in the order of the larger reactive power, so that control along a constant power factor becomes possible. Will be possible. In places where the load is large, the power factor can be kept constant with a small number of times of turning on / off by turning on / off the capacitor 23 having a large reactive power. On the other hand, when the sort control unit 18 is not provided as in the first embodiment, the capacitor 23 is continuously turned on until the required reactive power is reached. The same applies to the case where the control is opened, and the number of times of opening / closing is larger than that of the second embodiment, so that the control is inaccurate.

In the first and second embodiments, the capacitor reactive power calculator in the reactive power detector 13 controls each capacitor 23 under the control of the automatic open / close command unit 17.
The reactive power of each capacitor 23 is calculated only at the start of the operation of turning on and off the battery, and the calculated value is stored in the capacitor reactive power storage unit 14. Each time the capacitor 23 is turned on and opened, the reactive power of the turned on or opened capacitor 23 is calculated again by the capacitor reactive power calculating unit, and the calculated value is newly stored in the capacitor reactive power storage unit 14 ( That is, by rewriting), more accurate reactive power of each capacitor 23 can be stored in the capacitor reactive power storage unit 14, and control with even higher precision can be performed.

In this case, the capacitor reactive power calculation unit calculates
The number of times that each capacitor 23 has been turned on and off since the start of operation is counted (for example, two turns on,
(If it is open once, the count number will be 3 times).
Using the reactive power of the distribution line 4 detected by the reactive power detection unit 13, the absolute value of the amount of change in the reactive power is calculated, and the change in the reactive power when each capacitor 23 is turned on and opened from the start of operation. A value obtained by calculating the cumulative sum of the absolute values of the quantities, dividing the cumulative sum by the above counts of closing / opening as the reactive power of the capacitor 23, and rewriting the value of the capacitor reactive power storage unit 14. is there. Therefore, at the start of operation, the reactive power of each capacitor 23 calculated in the same manner as in the first and second embodiments is stored in the capacitor reactive power storage unit 14. afterwards,
Each time each capacitor 23 is turned on or opened, the value of the reactive power of the turned on or opened capacitor 23 is rewritten.

The reactive power of the capacitor is 2πfCV
² (f is frequency, C is capacity, V is voltage), and f and V
Is proportional to Since f changes depending on the content of harmonics and V changes depending on the fluctuation of the voltage or the opening / closing of the capacitor, as described above, the cumulative sum of the absolute values of the change amounts of the reactive power can be obtained to obtain a more accurate capacitor 23. Reactive power can be determined.

[0037]

As is apparent from the above description, according to the present invention, at the start of the operation, the automatic opening / closing command section controls each of the capacitors to be sequentially connected to the electric circuit for a certain period of time and then disconnected. By calculating the reactive power of each capacitor by the reactive power calculation unit and storing it in the capacitor reactive power storage unit, it is not necessary to set the reactive power of the capacitor as in the past. The power can be stored in the capacitor reactive power storage. As a result, any combination of capacitances is possible as a group of capacitors to be controlled, and a large number of capacitors can be accurately controlled, and an inexpensive automatic power factor control device can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an automatic power factor control device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a control operation of an automatic opening / closing command unit at the start of operation of the automatic power factor control device according to the first embodiment of the present invention.

FIG. 3 is an operation explanatory diagram of the automatic power factor control device according to the first embodiment of the present invention.

FIG. 4 is a block diagram illustrating a configuration of an automatic power factor control device according to a second embodiment of the present invention.

FIG. 5 is an operation explanatory diagram of an automatic power factor control device according to a second embodiment of the present invention.

FIG. 6 is a diagram for explaining effects in the second embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a conventional automatic power factor control device.

FIG. 8 is an operation explanatory diagram of a conventional automatic power factor control device.

[Explanation of symbols]

 2 Control Capacitor Group 3 Load 4 Distribution Line 5 Instrument Transformer 6 Current Transformer 10, 10 'Automatic Power Factor Controller 11 Voltage Detector 12 Current Detector 13 Reactive Power Detector 14 Capacitor Reactive Power Storage 15 Controller 16 Output unit 17 Automatic open / close command unit 18 Sort control unit 21 Switch 22 Series reactor 23 Phase-advancing capacitor

Claims (3)

[Claims] An electric circuit reactive power detection unit for detecting reactive power of an electric circuit to which a slow load is connected, and a control of connection and disconnection of each capacitor of a capacitor group to and from the electric circuit by the electric circuit reactive power detection unit. A control unit that performs control based on the detected reactive power of the electric circuit and the reactive power of the capacitor to be controlled; and an automatic opening and closing command unit that performs control to connect and disconnect each capacitor sequentially to the electric circuit for a certain time at the start of operation. Detecting the amount of change in the reactive power of the electric circuit at the time of connection and disconnection of each capacitor by the automatic opening and closing command unit at the start of operation using the detection value of the electric circuit reactive power detection unit, Capacitor reactive power calculation unit that calculates the average value of the absolute value of the reactive power change amount and the absolute value of the reactive power change amount when disconnected as the reactive power of each capacitor An automatic power factor control device comprising: a capacitor reactive power storage unit that stores the reactive power of each capacitor obtained by the capacitor reactive power calculation unit and supplies the reactive power to the control unit. 2. A control unit according to claim 1, wherein when the capacitor is connected to the electric circuit, the capacitor is connected in ascending order of reactive power, and when disconnecting the capacitor from the electric circuit, control is performed such that the capacitor is separated in ascending order of reactive power. The automatic power factor control device according to claim 1, wherein 3. The capacitor reactive power calculation unit also detects the amount of change in the reactive power of the electric circuit when the control unit connects and disconnects each capacitor by using the detection value of the electric circuit reactive power detection unit, and operates each of the capacitors. At the time of connection and disconnection from the start, the cumulative sum of the absolute value of the amount of change in the reactive power of the electric circuit is calculated, and the number of times of connection and disconnection from the start of operation for each capacitor is counted. The value obtained by dividing the calculated cumulative sum by the number of times of connection and disconnection at the time of connection and disconnection as the reactive power of the capacitor, and rewriting the value of the capacitor reactive power storage unit. Automatic power factor control device as described.