JP3114279B2 - Automatic power factor adjustment device - Google Patents

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 adjusting device for improving a load power factor in an electric power system.

[0002]

2. Description of the Related Art Reactive power in a power system is generally delayed.
The power factor, which leads when the reactive power exceeds a predetermined limit.
For use (hereinafter simply referred to as capacitor)
If the voltage falls below the specified limit, shut off the capacitor.
Can improve the power factor of this power system.
You. An example of such a conventional automatic power factor adjusting device is shown in FIG.
It is shown in the block diagram. Here, the automatic power factor adjustment device
10, operation condition setting unit 20, determination unit 30, delay timer unit
40, order restriction unit 50, output state storage unit 60, output unit 7
0, a display unit 80 and the like. The detection unit 10 is a power system
Detecting section 11 having a voltage transformer PT connected in series
And the output of the current detector 12 having the current transformer CT.
Active power and reactive power of this power system
The detection is performed by the unit 13 and the reactive power detection unit 14. Operating condition setting
The section 20 sets the operating conditions of this device, and
Minimum load P_o, Capacitor input reactive power Q_C, Conde
Sensor reactive power Q_dAnd delay time for stable operation
Set t. And the set controllable minimum load value P
_oIndicates to the light load cutoff level determining section 31 of the determining section 30
Reactor input reactive power Q_cIs the capacitor input level judgment section
32, the capacitor cut-off reactive power Q_dIs a capacitor shield
The interruption level determination unit 33 informs the delay time t that the delay timer unit 40
Are sent and set respectively. Light load cutoff level judgment section
31 indicates that the output of the active power detector 13 is a light load cutoff level
If it is below, the cutoff signal S is sent to the delay timer unit 40. ₁Send
At the same time, the light load lamp 81 of the display unit 80 is turned on. Throw
The input level determination unit 32 detects the
When the value of the delay reactive power exceeds the input level,
Input signal S_TwoAnd the display unit 80
Is turned on. The interruption level determination unit 33
The value of the delayed reactive power detected by the active power detector 14 is
Level or the value of the advanced reactive power is above the shutoff level.
When the delay time is reached, the cutoff signal S_ThreeSend
And the leading light 83 of the display unit 80 is turned on. 84 is
This is an appropriate lamp for the display unit 80. The delay timer unit 40 is shut off
Signal S₁, S_ThreeOr closing signal S_TwoIs set in the setting section 20
Input to the sequence control unit 50 when the set delay time has elapsed
Signal S_tOr cutoff signal S_sSend

The sequence controller 50 and the output unit 70 will now be described. First, the output unit 70 drives the relay unit 72 by the driving unit 71 via the output state storage unit 60 in accordance with a command from the sequence controller 50. The relay section 72 includes a plurality of relays, here R _{1 to} R ₄ , and the plurality of relays R _{1 to} R ₄
Introducing or blocks each capacitor C ₁ -C ₄ by contacts. The order control unit 50 controls each of the relays R _{1 to} R of the output unit 70.
Control is performed by issuing a cyclic control signal so that ₄ has a uniform opening and closing frequency. The cyclic control signal is transmitted to the output unit 70 via the output state storage unit 60. The output state storage unit 60 stores the open / closed state of each of the relays R _{1 to} R ₄ of the output unit 70, which is fed back to the sequence control unit 50, and which relay is turned on in the closing state display unit 85 of the display unit 80, which capacitor among the capacitors C ₁ -C ₄ sends a display signal indicating whether it is turned on.

Next, an example of the operation of the automatic power factor adjusting apparatus in one day will be described with reference to FIGS. 4A, 4B, 5A, 5B, 5C, and 5D. Figure 24 (A) shows the load for 24 hours a day.
The operation diagram of this automatic power factor adjusting apparatus in one day changes when it changes as shown in the diagram shown in (B), that is, when applied to the active power P _i in (A) and the delayed reactive power Q _i in (B). Figure 5
(A), (B), (C), and (D). FIG.
(A) is the same diagram as FIG. 4 (B). FIG. 4 (A)
In (B), the active power P _i kW starts increasing at about 7:00 and decreases at a maximum from 10:00 to 11:00 from 12:00 to 13:00, but thereafter keeps a substantially constant value until 17:00, and gradually decreases after 17:00. . The change of the delayed reactive power Q _i shown in FIG. _11B is almost the same as that of the active power P _i . Capacitor C ₁ -C ₄ against which is turned and blocking as shown in FIG. 5 (B) (D). Here, (B) is a diagram of the total capacitance C _k kVA of the input capacitors, and (D) is a diagram of each capacitor C kVA.
Indicates the capacity kVA of ₁ -C _4, circles blocking, a black dot indicates the power. The (C) is a broken line L ₁ in the diagram of reactive power Qkvar after power factor improving cutoff level, a broken line L ₂ denotes a poured level. When 7:00 reactive power Q _i is increased 100Kvar, each capacitor C ₁ -C having been cut off until then
Capacitor C ₁ of ₄ are turned on, the reactive power Q after power factor correction becomes zero. At 8:00, the reactive power _Qo was 200
If it slightly exceeds kvar, a total of 250 kVA of the _two capacitors C ₁ and C _{2 is} switched on. Therefore, the reactive power Q after the power factor improvement is advanced to 50 kvar. Further, at 9:00, even if the reactive power Q _iA exceeds 300 kvar, the capacitor C ₃ is not turned on, so the reactive power Q is delayed and the reactive power 100 kvar
become. Followed by 10 o'clock reactive power Q _i is the reactive power Q after more than when the whole of the capacitor C ₁ -C ₄ Total 500kVA is turned power factor correction 500kvar becomes zero. And 11
Sometimes, when the reactive power Q _i is less than 400 kvar, the first input capacitor C ₁ 100 kVA is cut off, and the reactive power after power factor improvement is slightly advanced and changes to reactive power. Such operation is repeated, the reactive power Q after the power factor improvement fit substantially blocking level L ₁ in the range of inputs level L _2.

[0005]

Automatic power factor adjusting device is generally [0005], or reduce the number of capacitors (corresponding to the C ₁ -C _4), for more detailed power factor control, the capacitance of each capacitor Different capacity control with different capacities is performed. In the automatic power factor adjusting apparatus described above, these capacitors are turned on or off at a fixed closing level or shutoff level. Therefore, no particular problem occurs when the capacity of each capacitor is constant. If the capacitance of each capacitor is different in the control, if the setting range of the closing level and the cutoff level is larger than the maximum capacitor capacity of each capacitor, the accuracy of the power factor control will be reduced. When a large capacitor is cut off, there is a problem that a hunting phenomenon that repeats turning on and off occurs.

SUMMARY OF THE INVENTION An object of the present invention is to prevent a hunting phenomenon that occurs when, for example, a large-capacity capacitor is cut off in an automatic power factor regulator of different capacity control in which phase-advancing capacitors are composed of capacitors having different capacities. .

[0007]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention detects reactive power of a power system, and switches on or shuts off a plurality of phase-advancing capacitors having different capacities based on the detection result. An automatic power factor adjusting apparatus for adjusting a power factor of the power system, wherein a voltage detecting unit for converting a voltage of the power system to detect a voltage, and a current detecting unit for converting a current of the power system to detect a current Unit, an active power detection unit that detects active power from the detected voltage and current, a reactive power detection unit that detects reactive power from the detected voltage and current, and a power factor that detects a power factor from the detected voltage and current The detection unit sets and stores operation conditions of a minimum controllable load, a target power factor, a voltage transformation ratio of the voltage detection unit, a current transformation ratio of the current detection unit, a capacity of the capacitor, and an operation delay time. Operating conditions An input level calculating section for calculating an input level of the capacitor based on the respective operating conditions set by the operating condition setting section and the value of the active power detected by the active power detecting section; And a cut-off level calculation unit for calculating a cut-off level from the minimum value of the input capacitor capacity, a delay reactive power change amount calculation unit for calculating a change amount of the delay reactive power exceeding the capacitor turn-on level, A reactive power change amount calculating section that calculates a change amount of the advance reactive power exceeding the delay reactive power change amount or the lead reactive power change amount during a delay time set by the operation condition setting section and averages the integrated values. A reactive power integrating unit for obtaining a value, and a storage for storing a capacitor which has already been turned on and a capacitor which is to be turned on among the capacitors. Capacitor capacity storage unit, the closing level calculating section or the cut-off level calculating
Section, operating condition setting section, input capacitor capacity storage section, and invalid
From the power integration unit to a closing capacitor with a capacity close to the average value of the delayed reactive power change calculated by the reactive power integration unit.
Select from among the blocked capacitors and
Of the amount of advance reactive power change calculated by the reactive power
Optimum on / off capacitor capacity selection unit to select from among capacitors that have a shunt capacitor with a capacity close to the average value, and shut off the shunt capacitor selected by the on / off optimum capacitor capacity selection unit In this case, it is determined whether or not hunting in which the turning on / off of the capacitor is repeated occurs.If it is determined that hunting occurs, the turning on / off is performed.
A hunting determination unit that selects a capacitor having the next closest capacitance to the cut-off optimum capacitor capacitance selection unit and repeats until the hunting is determined not to occur sequentially. An output unit that cuts off a cutoff capacitor that is selected by the selection unit and determined that hunting does not occur in the hunting determination unit, an output state storage unit that stores a state of the output unit, and an operation display unit that displays an operation of each unit. Be prepared. In addition, when there are a plurality of capacitors having the capacities closest to the average value calculated by the reactive power integration unit, the closing / cutting optimum capacitor capacity selecting unit is cut off first at the time of turning on from the past turning on / off data. Select a capacitor, and select the capacitor that was turned on first when shutting off.

[0008]

[Operation] The operating condition setting section directly sets the values of the minimum controllable load, target power factor, voltage transformation ratio, current transformation ratio, capacitor capacity, and delay time, and automatically determines the closing level and cutoff level from the stored data. To calculate. The delay and advance reactive power change amount calculation units calculate the value of the reactive power exceeding the input and cutoff levels, and this calculated value is compared with the input level and the input level during the delay time set by the reactive power integration unit in the operation condition setting unit. The value of the instantaneous reactive power exceeding the cutoff level is integrated, and the average value of the reactive power over the time is calculated. The input / output optimum capacitor capacity selection unit selects an input or output capacitor having a capacity close to the average value of the reactive power obtained by the reactive power integration unit from the respective capacitors. When there are a plurality of capacitors having capacities close to the average value of the reactive power, a capacitor which is cut off or turned on earlier in the past is selected. The hunting determination unit determines whether the difference between the reactive power of the power system and the reactive power at the closing level becomes positive or negative with respect to the cut-off capacitor selected by the closing / cutting optimum capacitor capacity selecting unit. It is determined whether or not hunting occurs. When it is determined that the difference is negative and hunting does not occur, the output unit is controlled to shut off the capacitor, and when it is determined that the difference is positive and hunting occurs, the control signal is turned on / off optimally. Return to the capacitor capacity selection section. The next closest capacitor is selected in the closing / cutting optimum capacitor capacity selection section, and the hunting determination section makes the same determination.If the difference is positive, the next closest capacitor is selected. It repeats until the difference becomes negative, at which point the output section is controlled to shut off the capacitor. In addition,
The switching capacitor selected by the switching capacitor selection section is turned on as it is.In this case, turning on this capacitor may cause the reactive power of the power system to exceed the cutoff level. The above-described hunting determination is performed on the power capacitor. In this way, a hunting phenomenon that occurs when a capacitor, particularly a capacitor having a large capacity, is cut off is prevented.

[0009]

FIG. 1 is a block diagram showing an embodiment of an automatic power factor adjusting apparatus according to the present invention. In FIG. 1, the automatic power factor adjusting apparatus includes a detecting unit 10, an operating condition setting unit 20, an output state storing unit 60, an output unit 70, a display unit 80, and the like, as in the prior art. Is further enhanced as shown below. In addition, the operation unit 100,
The system includes a reactive power integrating unit 110, a closing / cutting optimum capacitor capacity selection unit 120, a closing capacitor capacity storage unit 130, and a hunting determination unit 140.

The detecting unit 10 includes a voltage transformer PT and a current transformer C, which are connected to the power system, respectively, as in the conventional one.
It is connected so that the active power and the reactive power of this power system are detected by the active power detector 13 and the reactive power detector 14 by the outputs of the voltage detector 11 and the current detector 12 having T. Are connected so that the power factor detecting section 15 detects the power factor. The operating condition setting unit 20 sets the minimum controllable load P _O , the target power factor cos θ ₁ , the voltage transformation ratio γ ₁ of the voltage detection unit, the current transformation ratio γ ₂ of the current detection unit, the capacitor C, and the delay time t. , Operating condition storage unit 21
Stores all set conditions, and provides these conditions when necessary for calculation in control. The operation unit 100 includes a closing level operation unit 101, a cutoff level operation unit 102, a delayed reactive power change amount operation unit 103, and a leading reactive power change amount operation unit 104. Various operations described later are performed from the data detected in. These calculation data are stored in the reactive power integrating unit 1
The reactive power accumulating unit 110 calculates the average value of the lagging or advancing reactive power change amount, and sends the calculated average value to the input / cut-off optimum capacitor capacitance selecting unit 120. The input / output optimum capacitor capacity selection unit selects an input / output capacitor whose capacity is close to the average value of the lag or advance reactive power change amount from each capacitor, and sends a control signal to the hunting determination unit 140. The hunting determination unit 140 determines whether or not hunting occurs when the selected cut-off capacitor is cut off when this capacitor is cut off. If it is determined that hunting occurs, the hunting determination unit 140 sends a control signal to the input / cut-off optimal capacitor capacity selection unit. 120, a capacitor having the next closest capacitance is selected, and the process is repeated until it is determined that hunting does not occur.
And outputs a cutoff signal to cut off the capacitor. In addition,
An input signal is output to the selected input capacitor and input as it is.

The output state storage unit 60 includes a hunting determination unit 1
When receiving the input signal of 40, the data of the input capacitor is transmitted to the input capacitor capacity storage unit 130. The input capacitor capacity storage unit 130 stores the capacities of the capacitors that have been supplied and are about to be supplied in comparison with the data of the capacities of all the capacitors C _{1 to} C ₄ sent from the operation condition storage unit 21. The information is sent to the cut-off level calculation unit 102 as data for calculating the cut-off level, and the information is provided to the input / cut-off optimum capacitor capacity selection unit 120 in order to determine the capacitor to be cut off.

The display section 80 includes a display element drive section 86, a lead / lag capacitance value display 87 and a unit display 88 driven by the display element drive section 86, in addition to the conventional ON state display section 85.

Next, the operation of the arithmetic unit 100 and thereafter will be described in detail. Charged level calculating section 101, transformation ratio gamma ₂ and the detection unit 10 of the controllable minimum load and the target power factor cos [theta] ₁ set in SeiJobu 20 P _o and the voltage transformer transformation ratio of PT gamma ₁ and the current transformer CT The active power P detected by
_i calculates the charged level the reactive power Q ₁ in the following equation (1) if it exceeds the controllable minimum load P _o.

[0014]

(Equation 1)

The lagging reactive power variation amount calculation section 103, the active power P _i is the reactive power detected by reactive power detector 14 at the time of exceeding the value of the controllable minimum load P _o Q _i of the effective power detector 13 And a difference between the input level reactive power Q ₁ and ΔQ _ai . Blocking level calculating unit 102, the minimum value C _m (1) charged level the reactive power Q _1, hunting coefficient k calculated by the formula of the capacitance of the capacitor which is currently put
Then, the interruption level reactive power Q ₂ is calculated by the following equation (2).

[0016]

(Equation 2)

Here, the hunting coefficient k is a coefficient for preventing hunting which repeatedly turns on and off the capacitor, and is about 1.1 to 1.2. Cutoff level the reactive power Q ₂ this time is the leading reactive power to become negative. The advanced reactive power variation calculator 104 sets ΔQ _{bi as} the difference between the reactive power Q _i detected by the reactive power detector 14 (a negative value when advanced) and the cutoff level reactive power Q ₂ .

The reactive power accumulating section 110 determines whether the difference ΔQai between the delayed reactive power Qi and the input level reactive power Q ₁ has become a positive value during the delay time set by the settling section 20, or the reactive power Qi. The reactive power Qi is integrated from the time when the difference ΔQbi from the cutoff level reactive power Q ₂ becomes a negative value, and the integrated values Qa,
Obtain Qb. However, when the reactive power Qi and the input level difference of the reactive power Q ₁ ΔQai continues the positive value to accumulate, but stops integrating when a negative value, the integrated value 0
And Also when the difference between the reactive power Qi and blocking level reactive power Q ₂ ΔQbi continues a negative value, performs multiplication, the integrated value to stop the integration when it becomes a positive value to zero.
Then, when the delay time has elapsed, the integrated values Qa and Qb are divided by the number of times of integration to obtain average values ΔQa and ΔQb. Charged capacity Q _A further two transformation ratio gamma _1, by multiplying the gamma _2, to calculate the breaking capacity Q _B. The value of the input capacitance Q _A is when the positive is necessary to put the capacitor close to the capacity. So it turned, blocking optimum capacitor selection unit 120 selects one from among the capacitors that are currently blocked closest capacitor to the value of the input capacitance Q _A, when the capacitor close to the value of the input capacitance Q _A there are a plurality, Among them, the capacitor that was cut off earlier in the past is selected and a control signal for the closing operation is output. The value of the breaking capacity Q _B is when the negative is necessary to cut off the capacitor close to the capacity. So it turned, blocking optimum capacitor selection unit 120 is the closest one capacitor selection of the value of the breaking capacity Q _B from the capacitor that is currently turned when the capacitor close to the breaking capacity Q _B have multiple, among them Selects the capacitor that was turned on earliest in the past and outputs a control signal for the shutoff operation. These control signals are input to the hunting determination unit 140. Hunting judgment unit 140
Is the reactive power of the power system when this capacitor is cut off, that is, the reactive power Qi of the current power system and the selected cut-off capacitor with respect to the cut-off capacitor selected by the closing / cutting optimum capacitor capacity selection unit 120. the sum Qi + Cj and reactive power Cj, difference ΔQai = (Qi + Cj) of the turned level reactive power Q ₁ calculates a -Q _1. And outputting a blocking signal to the output unit 70 the reactive power Qi is via the output state storage unit 60 determines that the hunting does not occur because falls within turned level reactive power Q ₁ by blocking capacitors when the difference ΔQai is negative Then, the drive unit 71 is controlled, and the relay corresponding to the corresponding capacitor of the relay unit 72 is turned off. Also, this time difference ΔQai is positive returns control signals to the decision to put and interruption optimum capacitance selection unit 120 and therefore it is necessary to put a further capacitor also blocks the capacitor hunting occurs, the input- The cutoff optimum capacitor capacity selection unit 120 selects a capacitor having the next closest capacitance, and the hunting determination unit 140 makes a similar determination. If the difference is positive, the next closest capacitor is selected. The process is repeated until the difference becomes negative. When the difference becomes negative, the relay corresponding to the corresponding capacitor is turned off in the same manner as described above. The hunting determination section 140 outputs a closing signal to the output section 70 via the output state storage section 60 and inputs the input capacitor as it is selected by the closing / cutting optimum capacitor capacity selecting section 120. Although If this reactive power Qi of the power system by the capacitor is turned on exceeds the cutoff level Q ₂ occurs, the determination described above of the hunting is performed on the capacitor to be cut off then at this time.

[0019] Figure 2 is a vector diagram illustrating the operation of the hunting determination of the automatic power factor adjusting device of the present invention shown in FIG. 1, the power X ₁ of lagging power factor, for example a controllable minimum load Po larger effective power It is supplied, delayed reactive power Qi of the power X ₁ is a closing level greater than the reactive power Q _1. Thus turned, blocking optimum capacitor selection section 120 is turned on capacitor in this example selects the capacitor C _1, power X ₁ and this capacitor is as turned chosen is improved power factor moved to the power X _2. Cutoff level by capacitor C ₁ is turned on reactive power Q ₂ (C ₁₎ is
(2) Q ₂ = a minimum value Cm of the capacitor capacitance of _{Q 1 -kCm / γ 1 · γ} 2 the curve obtained by putting the capacitance of the capacitor C _1. When moved from the power X ₂ to the power X ₃ wherein changing the power, the lagging reactive power Qi is larger than charged level the reactive power Q ₁ again, the a is turned is selected similarly capacitor C ₂ power to move to X _4.
However, since the power X ₄ exceeds the cut-off level reactive power Q ₂ ( C ₁ ), it is necessary to cut off either the supplied capacitor C ₁ or C ₂ . for example selecting a capacitor C _2,
The control signal is output to hunting determination section 140. The hunting determination unit 140 determines the reactive power of the power system when the capacitor C ₂ is cut off, that is, the reactive power Qi of the current power system and the reactive power Cj of the cut off capacitor C _2.
(C ₂ ) sum Qi + Cj (C ₂ ) and input level reactive power Q
₁ the difference ΔQai = {Qi + Cj (C 2)} - calculating the Q _1.
Since this value exceeds the charged level the reactive power Q ₁ As is apparent from the movement of the power in the C ₂ blocking indicated by the broken line in FIG. 2, i.e. ΔQai since a positive, hunting determining section 140 when the hunting occurs Judge and return the control signal to the closing and closing optimum capacitor capacity selection unit 120,
In the cutoff optimum capacitor capacity selecting section, a capacitor having the next closest capacity, in this case, the capacitor C1 is selected, and similarly, in the hunting determining section 140, ΔQai = ｛Qi + Cj
(C ₁ )｝ − Q ₁ is calculated. This value is within turned level reactive power Q ₁ As is clear from the power transfer during the C ₁ blocking of Figure 2, i.e. ΔQai since become negative, hunting determining section 140 determines that not occur hunting It controls the output unit 70 Te to block this capacitor C _1. The only the capacitor C ₂ to the power system by the blocking of the capacitor C ₁ is cut off level are turned reactive power Q ₂ (C
₂₎ is a curve obtained by putting the capacitance of the capacitor C ₂ to a minimum value Cm of (2) _{Q 2 = Q 2 -kCm / γ} 1 · γ 2 of the capacitance. The leading reactive power of the power X ₅ after the capacitor C ₁ is cut off isolation level reactive power Q ₂ (C ₂₎
Since the following is entered, no further turning on / off of the capacitor is performed. In this way, hunting when the capacitor is shut off can be completely prevented.

The display element driving section 86 of the display section 80 drives the advance / lag / numerical display 87 and the unit display 88. The current load status of the system is checked by the signals from the detection units 13, 14, and 15, the value set by the signal from the operation condition storage unit 21 is checked, and the input level reactive power Q ₁ is checked by the signal from the input level calculation unit 101. values, and displays the respective values of the cut-off level the reactive power Q ₂ at the signal cutoff level calculating section 102 of the. The input state display unit 85 corresponds to each of the capacitors C _{1 to} C ₄ , and blinks an indicator light corresponding to the capacitor selected by the optimum capacitor capacity selection unit 120 before the relay unit 72 operates, thereby notifying the lamp. Lights when turned on when turned on and turns off when shut off. Each setting of the operating condition setting unit 20 may be configured to be easily operated by a digital switch or the like.

[0021]

As described above, according to the present invention, it is determined whether or not hunting occurs when the cutoff capacitor selected by the closing / cutting optimum capacitor capacity selection section is cut off. When it is determined that hunting occurs, a hunting determination unit that repeats until it is determined that hunting does not occur by selecting a capacitor having the next closest capacitance in the closing / closing optimum capacitor capacitance selection unit is provided. For example, in an automatic power factor control device of a different capacity control capable of reducing the number of capacitors and having different capacities of the respective capacitors and capable of precise control at a low cost, shut off the capacitors, especially the capacitors having a large capacity. Hunting does not occur, preventing damage to the capacitor or relay due to hunting. It is of course, but the effect is significant to improve the stability of the power system.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an automatic power factor adjusting apparatus according to the present invention.

FIG. 2 is a vector diagram illustrating an operation of a hunting determination of the automatic power factor adjusting apparatus of the present invention shown in FIG. 1;

FIG. 3 is a block diagram showing an example of a conventional automatic power factor adjusting device.

[Figure 4] is a load diagram of a conventional automatic power factor adjustment mechanism shown in FIG. 3, (A) is the diagram of the active power P _i, (B) is a line diagram of the lagging reactive power Q _i

FIG. 5 illustrates the operation of the conventional automatic power factor adjusting device shown in FIG.
It is a figure, (A) is reactive power Q _ikvar diagram, (B)
Diagram of the total capacitance of the input capacitors, CokVA, (C) is the power factor
Diagram of reactive power Qkvar after improvement, (D) shows each capacitor
C₁~ C_FourIndicates the capacity kVA, circles indicate cutoff, black circles indicate
ON / OFF state diagram showing ON

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Voltage detection part 12 Current detection part 13 Active power detection part 14 Reactive power detection part 15 Power factor detection part 20 Operating condition setting part 60 Output state storage part 70 Output part 80 Display part 101 Input level calculation part 102 Cutoff level calculation part 103 Delayed reactive power change amount calculation unit 104 Leading reactive power change amount calculation unit 110 Reactive power calculation unit 120 Optimum capacitor capacity selection unit for closing / cutting 130 Capacitor capacity storage unit 140 Hunting determination unit

Claims (2)

(57) [Claims] 1. An automatic power factor adjustment for detecting a reactive power of a power system and for turning on or off a plurality of phase-advancing capacitors having different capacities based on the detection result to adjust a power factor of the power system. In the device, a voltage detection unit that transforms a voltage of the power system to detect a voltage, a current detection unit that transforms a current of the power system to detect a current, and an active device that detects active power from the detected voltage and current A power detector, a reactive power detector that detects reactive power from the detected voltage and current, a power factor detector that detects a power factor from the detected voltage and current, a controllable minimum load, a target power factor, and the voltage detection. Operating condition setting unit for setting and storing the operating conditions of the voltage transforming ratio of the unit, the current transforming ratio of the current detecting unit, the capacity of the capacitor, and the operation delay time, and each settled by the operating condition setting unit. Operating condition An input level calculator for calculating an input level of the capacitor capacity based on the active power value detected by the active power detector, and an interrupt level for calculating an interrupt level from the input level and the minimum value of the input capacitor capacity. A calculating section, a lag reactive power change amount calculating section for calculating a lag reactive power change amount exceeding the capacitor input level, and a lag reactive power change calculating section for calculating a lag reactive power change amount exceeding the capacitor cutoff level to the leading power factor side. Amount calculating unit, the lagging reactive power change amount or the leading reactive power change amount is integrated for a delay time set by the operating condition setting unit, and a reactive power integrating unit for obtaining an average value thereof; charged capacitor capacity storage unit for storing the capacitance of the capacitor and be currently turned were, walk the closing level calculating section Cutoff level computing
Section, operating condition setting section, input capacitor capacity storage section, and invalid
From the power integration unit to a closing capacitor with a capacity close to the average value of the delayed reactive power change calculated by the reactive power integration unit.
Select from among the blocked capacitors and
Of the amount of advance reactive power change calculated by the reactive power
Optimum on / off capacitor capacity selection unit to select from among capacitors that have a shunt capacitor with a capacity close to the average value, and shut off the shunt capacitor selected by the on / off optimum capacitor capacity selection unit In this case, it is determined whether or not hunting in which the turning on / off of the capacitor is repeated occurs.If it is determined that hunting occurs, the turning on / off is performed.
A hunting determination unit that selects a capacitor having the next closest capacitance to the cut-off optimum capacitor capacitance selection unit and repeats until the hunting is determined not to occur sequentially. An output unit that cuts off a cutoff capacitor that is selected by the selection unit and determined that hunting does not occur in the hunting determination unit, an output state storage unit that stores a state of the output unit, and an operation display unit that displays an operation of each unit. An automatic power factor adjusting device, comprising: 2. The automatic power factor adjusting apparatus according to claim 1, wherein the switching on / off optimal capacitor capacity selecting section is configured to determine a past capacitor when a plurality of capacitors having a capacity closest to the average value calculated by the reactive power integrating section exist. An automatic power factor adjusting device characterized in that, based on the data of closing and shutting off, a capacitor that is shut off first is selected at the time of shutting down, and a capacitor that is turned on first is selected at the time of shutting down.