JP3146514B2 - 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 a lagging power factor. When the reactive power exceeds a predetermined limit, a leading capacitor is turned on, and when the reactive power falls below a predetermined limit, the leading capacitor is shut off. As a result, the power factor of the power system can be improved. An example of such a conventional automatic power factor adjusting device is shown in a block diagram of FIG. Here, the automatic power factor adjusting device includes a detecting unit 10, an operating condition setting unit 20, a determining unit.
30, delay timer section 40, sequence control section 50, output state storage section 6
0, an output unit 70, a display unit 80, and the like. The detection unit 10 detects the active power and the reactive power of the power system by the output of a voltage detection unit 11 having a voltage transformer PT connected to the power system and a current detection unit 12 having a current transformer CT. 13 and the reactive power detector 14. Operating condition setting section
Reference numeral 20 designates an operation condition of the apparatus, which sets a controllable minimum load _Lo , a capacitor input reactive power _Qc , a capacitor shutoff reactive power _Qd, and a delay time t for stable operation. Then, the set minimum controllable load value _Lo is sent to the light load cutoff level judging section 31 of the judging section 30, and the capacitor input reactive power value _Qc is sent to the capacitor input level judging section 32.
The capacitor cut-off reactive power value _Qd is sent to the capacitor cut-off level judging section 33, and the delay time t is sent to the delay timer section 40 for setting. If the output of the active power detection unit 13 is equal to or less than the light load interruption level, the light load interruption level determination unit 31 transmits the interruption signal S ₁ to the delay timer unit 40 and displays the display unit 80.
The light load lamp 81 is turned on. Charged level determination unit 32, when the value of the lagging reactive power detected by reactive power detector 14 exceeds the charged level, turns on the delay lamp 82 of the display unit 80 transmits the activation signal S ₂ to the delay timer 40 I do. Blocking level determining unit 33, when the value of the lagging reactive power detected by reactive power detector 14 is the value of the cutoff level or lower, or proceeds reactive power is equal to or greater than cutoff level, an interruption signal S ₃ to the delay timer 40 At the same time, the advance light 83 of the display unit 80 is turned on. 84 is a proper lamp of the display unit 80. The delay timer unit 40
When shutdown signal S _1, S ₃ or on signal S ₂ has passed the delay time set by the settling unit 20 transmits the activation signal S _t or blocking signal S _s to the sequence control unit 50.

Here, the order control unit 50 and the output unit 70 will be described.
To be described, first, the output unit 70 is in accordance with a command from the sequence control unit 50.
Driving unit 71 drives relay unit 72 via output state storage unit 60
I do. The relay unit 72 includes a plurality of relays, here R₁~ R_Four
And the plurality of relays R ₁~ R_FourEach contact
Capacitor C₁~ C_FourSwitch on or off. Order control unit
50 is each relay R of the output unit 70₁~ R_FourWith uniform opening and closing frequency
The control is performed by issuing a cyclic control signal so as to be as follows. Sa
The click control signal is output via the output state storage unit 60
It is transmitted to the unit 70. The output state storage unit 60 stores each resource of the output unit 70.
Leh R₁~ R_FourThe opening / closing state of the
Feeding back to 0 and display state table of display unit 80
Which relay is turned on in the display section 85 and each capacitor C₁~ C_Four
Signal that indicates which capacitor is turned on.
Send the issue.

Next, an example of one day of operation of the automatic power factor adjusting apparatus will be described with reference to FIGS. 6 (A) (B) and 7 (A) (B) (C) (D). 1
The load for 24 hours a day changes as shown in the graphs of FIGS. That is, when applied to the active power Pi of (A) and the delayed reactive power Qi of (B), the daily operation diagram of this automatic power factor adjusting device is shown in FIGS. 7 (A) (B) (C) (D) Changes as shown in FIG. FIG. 7 (A) is the same diagram as FIG. 6 (B). In FIGS. 6 (A) and 6 (B), the active power Pi kW starts to increase 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 at 17:00. It gradually decreases thereafter. The change of the delayed reactive power Qi shown in FIG. 9B is almost the same as that of the active power Qi. On the other hand, the capacitor C ₁
-C ₄ is turned and blocking as shown in FIG. 7 (B) (D). Here (B) is a diagrammatic view of a total capacity CokVA of input capacitors, (D) shows the capacity kVA of the capacitors C ₁ -C _4,
A circle indicates shut off, and a black circle indicates injection. Also the (C) is a broken line L ₁ in the diagram of reactive power Qkvar after power factor improving cutoff level,
Dashed line L ₂ indicates the charged level. When 7:00 reactive power Q _i is increased 100Kvar, the capacitor C ₁ of the blocked capacitor C ₁ each had -C ₄ is turned, the reactive power Q after power factor correction becomes 0 before. Subsequently, when the reactive power Qo slightly exceeds 200 kvar at 8:00, two capacitors C ₁ and C _2, 250 kVA in total, are supplied. Therefore, the reactive power Q after the power factor improvement advances and the reactive power 50 kv
ar. Furthermore mode capacitor C ₃ o'clock reactive power QiA exceeds the 300Kvar 9 is reactive power Q do not thrown becomes delayed reactive power 100Kvar. Subsequently, when the reactive power Qi exceeds 500 kvar at 10 o'clock, all the capacitors C ₁ to C ₁ .
C ₄ total 500kVA reactive power Q after being turned on power factor improvement
Becomes 0. At 11:00, the reactive power Qi is 400 kvar
Is less than the capacitor C ₁ 100
The kVA is cut off, the reactive power after the power factor improvement slightly advances, 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]

In the above-described conventional apparatus, as shown by the hatched area in FIG. 7 (C), the reactive power increases after the power factor is improved, and in a system with a large load fluctuation, the output switching frequency is increased. And the life of the capacitor switch is shortened. On the operation side, the input reactive power and cut-off reactive power of the operating condition setting section are converted into reactive power by calculation from the target power factor, and the values are converted into the transformer transformation ratio and transformer transformation ratio in the detection section. The method has a drawback that it is very troublesome because the method is set to a value obtained by dividing by the synthesis ratio. In addition, since the input level (input reactive power) is constant and the power factor at the time of intermediate load is set to exceed the target power factor, the proper display is displayed even after all capacitors are turned on at maximum load. However, there is a problem that the state of the delay display continues. To solve this problem, the input level (input reactive power) so that an appropriate display is displayed at the maximum load.
Is set, there is a disadvantage that the power factor at the time of the intermediate load is lower than the target power factor.

An object of the present invention is easy to settling operating conditions, the input of the capacitor, and to reduce the cut-off number is possible to extend the life of the capacitor switch and
Another object of the present invention is to provide an automatic power factor adjusting device capable of displaying an appropriate display when all capacitors are turned on at the maximum load.

[0007]

To solve the above object, according to an aspect of the present invention detects the reactive power of the power system, the power of the power system a phase advancing capacitor on the basis of the detection result on or cut off to In an automatic power factor adjusting device that adjusts a power factor, a voltage detection unit that detects a voltage by transforming a voltage of the power system, a current detection unit that detects a current by transforming a current of the power system, and the detected voltage. An active power detector for detecting active power from current, a reactive power detector for detecting reactive power from the detected voltage and current, and an improvement of the power system
The target power factor, the voltage transformation ratio of the voltage detection unit, the current transformation ratio of the current detection unit, and the capacity of the capacitor can be controlled.
An operation condition setting unit for setting and storing operation conditions of a minimum load, an intermediate load, and an operation delay time, and a load of the power system.
The target power factor, voltage transformation ratio, current transformation ratio,
Based on the controllable minimum load and the value of the active power detected by the active power detection unit, a large value equal to or less than the intermediate load capacity value is used.
For the load of the magnitude, from the intermediate load capacity and the target power factor,
Exceed the intermediate load capacity value below the calculated reactive power value
Charged level calculating unit for calculating a projection <br/> input level so that the target power factor or power factor for the load, the capacitor
Of capacitors already turned on
Capacitor storage to store the capacity of the capacitor
Parts, the blocking level calculating unit for calculating a cutoff level charged level from the minimum value of the closing capacitance, the excess in the charged level lagging behind lagging reactive power variation amount calculating section for calculating the amount of change in reactive power, the A leading reactive power change amount calculating unit that calculates a leading reactive power change amount that exceeds a cutoff level to a leading side, the delayed reactive power change amount or the leading reactive power change amount during a delay time set by the operating condition setting unit. A reactive power integrating section for integrating and calculating an average value thereof, the input level calculating section, an operating condition setting section, and an input capacitor capacity.
Determine the input capacitor from the amount storage unit and the reactive power integration unit
The cutoff level and the input capacitor capacity storage unit are invalid.
An optimum capacitor capacity determining unit for determining a capacitor to be cut off from the power integrating unit , an output unit having a drive unit for turning on or off the capacitor according to the determination of the optimum capacitor capacity determining unit, and an operation display for displaying the operation of each unit. characterized in that a part.

In the above automatic power factor adjusting apparatus,
The phase lead capacitors are divided into several groups in different capacity groups.
With a large capacity group of capacitors.
Capacitors of the same capacity closest to the average value calculated by the arithmetic unit
When there are multiple
When turning on, turn on the capacitor that was shut off first and shut off.
In the event of a power failure, the first inserted capacitor will be shut off.
It is characterized by the following.

[0009]

[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 turns on and off levels 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 switching on / off optimum capacitor value determining unit selects a capacitor value close to the average value of the reactive power obtained by the reactive power integrating unit from each capacitor group. When there are a plurality of capacitors having a capacity close to the average value of the reactive power, the capacitor which was cut off or turned on earlier in the past is selected and turned off or turned on. The input level (input reactive power) is automatically set so that the reactive power is constant in the low load area and the power factor is constant in the high load area according to the load size. In the case of the maximum load, an appropriate display is obtained.

[0010]

FIG. 1 is a block diagram showing an embodiment of an automatic power factor adjusting apparatus according to the present invention. In the figure, the automatic power factor adjusting device has a detecting unit 10 and an operating condition setting unit 2 similar to the conventional one.
0, an output state storage unit 60, an output unit 70, a display unit 80, etc., and the contents of these units are further enhanced as described below. In addition, a calculation unit 100, a reactive power integration unit 110, and an optimum closing / cutting capacitor value determining unit 120 are provided. The detecting unit 10 includes a voltage transformer PT and a current transformer CT, which are connected to the power system, respectively, as in the prior art.
With the outputs of the voltage detection unit 11 and the current detection unit 12 having, the active power and the reactive power of this power system are connected so as to be detected by the active power detection unit 13 and the reactive power detection unit 14.
Furthermore, the power factor is connected so that the power factor detecting unit 15 detects the power factor during this time. The operating condition setting unit 20 determines the minimum controllable load Po, the target power factor cos θ _1, and the voltage transformation ratio r ₁ of the voltage detection unit.
And the current transformation ratio r ₂ of the current detector, the capacitor C, and the delay time t, and the operating condition storage 21 stores all the set conditions, and provides these conditions if necessary for calculation in control. I do. The operation unit 100 is the input level operation unit 10.
1, cut-off level calculator 102, delay reactive power change calculator
103 is provided with an advanced reactive power change amount calculation unit 104, and performs various calculations described later from the data detected by the detection unit 10 based on the numerical value set by the operation condition setting unit 20. Then, the operation data of the input level calculation section 101 and the cutoff level calculation section 102 are sent to the input / cutoff optimum capacitor capacity determination section 120 together with the data of the reactive power integration section 110, and are sent to the output section 70 via the output state storage section 60. Then, the drive unit 71 drives each of the relays R _{1 to} R ₄ to turn on or off each of the capacitors C _{1 to} C ₄ . This state is displayed on the display unit 80. The display section 80 includes a display element driving section 86 in addition to the conventional closing state display section 85, and a lead / lag capacitance value display driven by the display element driving section 86.
87 and a unit indicator 88 are provided.

Next, the operation of the arithmetic unit 100 and below will be described in detail. Charged level calculating section 101, the target power factor cos [theta] ₁ and controllable minimum load P ₀ set by SeiJobu 20 and the voltage transformer PT
By the transformation ratio r ₁ and the transformation ratio r ₂ of the current transformer CT, and calculates the charged level reactive power Q ₁ by the following equation.

[0012]

(Equation 1)

The delay reactive power change amount calculating section 103 determines that the active power Pi of the active power detecting section 13 is equal to the minimum controllable load Po.
The difference was calculated, Delta] Q of the charged level the reactive power Q ₁ reactive power Qi detected by reactive power detector 14 at the time of exceeding the value
ai. Blocking level calculating unit 102, a minimum value Cm (1) isolation level the reactive power Q ₂ by the following equation from the input level is calculated reactive power Q _1, hunting coefficient k in equation capacitance set by SeiJobu 20 calculate.

[0014]

(Equation 2)

Here, the hunting coefficient k is
A coefficient to prevent hunting that repeats closing and closing.
It should be about 1.1 to 1.2. At this time, the interruption level reactive power Q
_TwoBecomes negative reactive power. Advance reactive power change
The amount calculator 104 calculates the reactive power Q detected by the reactive power detector 14.
i and (negative value when leading) and the interruption level reactive power Q _Two
Is defined as ΔQbi.

The reactive power integrating section 110 is set by the settling section 20.
Reactive power Qi and input level reactive power
Force Q₁When the difference ΔQai becomes a positive value or reactive power
Qi and interruption level reactive power Q_TwoDifference ΔQbi becomes a negative value
The reactive power Qi is integrated from this point and the integrated values Qa, Qb
Get. However, the reactive power Qi and the input level reactive power Q
₁Difference ΔQa₁If the value continues to be a positive value,
However, when the value becomes negative, the integration is stopped and the integrated value is set to 0.
And Also, the reactive power Qi and the interruption level reactive power Q_TwoWhen
When the difference ΔQbi of the value continues to be a negative value, integration is performed,
When the value becomes a positive value, the integration is stopped and the integrated value is set to 0.
You. When the delay time has elapsed, the integrated values Qa and Qb are
By dividing by the number of times of integration, average values ΔQa and ΔQb are obtained. further
Both transformation ratios r ₁, r_TwoMultiplied by the input capacity Q_A, Breaking capacity Q
_BIs calculated. Input capacity Q_AWhen the value of is positive, its capacity
It is necessary to insert a capacitor close to. So the best
Capacitor determination section 120 is the input capacity Q_ACon
Select one of the capacitors that are currently blocking the capacitor,
The drive unit 71 is controlled via the output state storage unit 60 to
Turn on the relay corresponding to the capacitor. Input capacity Q_A
If there are multiple capacitors near the value of
For the closing operation
Send a control signal. Breaking capacity Q_BIf the value of is negative,
It is necessary to shut off a capacitor close to the capacity. So the most
The appropriate capacitor determination unit 120 determines the current
Breaking capacity Q_BThe capacitor closest to the value of
Select one and control the drive unit 71 via the output state storage unit 60
Then, the relay corresponding to the capacitor is turned off. Interception
Disconnection capacity Q_BWhen there are multiple capacitors close to
Select the capacitor that was turned on earlier in the past
Control signal for

The display element driving section 86 of the display section 80 drives the advance, delay, number display 87 and unit display 88. Each detector
13, strains with the signal from 14 and 15 the current load situation, the signal value of the input level the reactive power to Q ₁ from the confirmation and the input level calculating unit 101 and the value set by the signal from the operating condition storage unit 21 , displays each value of the cutoff level reactive power Q ₂ at the signal cutoff level calculating unit 102. The input state display section 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 determination section 120 before the relay section 72 operates, and informs the relay section 72 of this. Lights when turned on when turned on and turns off when shut off. It is preferable that each setting of the operating condition setting unit 20 be configured to be easily operated by a digital switch or the like.

In this embodiment, the change as shown in the daily load diagram shown in FIGS. 6A and 6B, that is, the active powers P ₁ and (B) shown in FIG.
2 (A) (B) (C) (D)
The power factor can be adjusted efficiently by the operation diagram shown in FIG. FIG. 2A is the same diagram as FIG. 6B.

Next, another embodiment of the present invention will be described with reference to FIG. 3, the automatic power factor adjusting apparatus includes a detecting unit 10, an operating condition setting unit 20, a determining unit 30, an output state storing unit 60, an output unit 70, a display unit 80, and the like as in FIG. The contents of each of these parts are further enhanced. Also,
In addition, a calculation unit 100, a reactive power integration unit 110, and an optimum capacitor capacity determination unit 120 are provided. The detection unit 10 includes the same components as the conventional one, and further includes a voltage detection unit 11 and a current detection unit.
A power factor detection unit 15 is connected to detect the power factor of the power system by the output of 12. Operating condition the settling section 20, the controllable minimum load P ₀ and the intermediate load P _a and the target power factor cos [theta] ₁ and the voltage transformation ratio r ₁ and the current transformation ratio r ₂ and capacitance C ₁ -C ₄
And the delay time t are set, and the operating condition storage unit 21 stores all the set conditions, and provides these conditions when necessary for control in calculation. The operation unit 100 includes a closing level operation unit 101, a cutoff level operation unit 102, a delay reactive power change amount operation unit 103, and a leading reactive power change amount operation unit 104, and detects the detection unit 10 based on the numerical value set by the operation condition setting unit 20. Various calculations are performed from each value detected in. The calculation data of the input level calculation unit 101 and the cutoff level calculation unit 102 together with the data of the reactive power integration unit 110 are combined with the optimum capacitor value determination unit 1.
Sent to 20. When the delay reactive power is generated and exceeds the input level on the delay side, from the data of the capacitor capacity of the operating condition storage unit 21 and the data of the input capacitor capacity storage unit 130,
The capacitor capacity closest to the reactive power change is determined,
The closing signal is sent to the output unit 70 via the output state storage unit 60, and the drive unit 71 drives the relay corresponding to the capacitor and turns on. This information is also sent to the display unit 80.

When receiving the input signal, the output state storage unit 60 transmits data indicating which capacitor is to be input to the input capacitor capacity storage unit 130. The input capacitor capacity storage unit 130 stores the current input capacitor capacity and the capacitor capacity that is about to be input in comparison with the data of all the capacitor capacities C _{1 to} C ₄ sent from the operating condition storage unit 21. In order to send information to the cut-off level calculating section 102 as data for calculating the cut-off level and to determine the capacitor to be cut off, the optimum capacitor capacity determining section 120
Provide information to The display unit 80 is, in addition to the display unit of FIG.
A light load indicator 81 is provided.

Next, the operation of turning on and off the capacitor of this embodiment will be described. Based on the target power factor cos θ ₁ , the intermediate load Pa, the transformation ratio r ₁ of the voltage transformer PT, and the transformation ratio r ₂ of the current transformer CT set by the setting unit 20, the input level calculation unit 101 determines the minimum controllable load Po for loads up to medium load Pa from calculates the charged level q ₁ as viewed in the automatic power factor adjusting device side by the following equation (3).

[0022]

(Equation 3)

However, when viewed from the primary side of the power system, the input reactive power Q ₁ is expressed by the following equation (4).

[0024]

(Equation 4)

For loads exceeding the intermediate load Pa,
q ₁ and Q ₁ are switched as in the following equation (5).

[0026]

(Equation 5)

Here, Pi is the active power itself detected by the active power detector 13. The delay reactive power change amount calculation unit 103 sets the active power Pi of the active power detection unit 13 to the value of the minimum controllable load Po, which is 150 kW in FIG. detected reactive power Qi turned levels Q ₁ (the secondary side q ₁₎ calculates the difference between, the DerutaQai. Blocking level calculating unit 102, among the data of the input capacitance storage unit 130, the minimum capacitance Cm and (3) and (4) isolation level by the following equation from the input levels q ₁ and hunting coefficient k calculated by the formula q ₂
Is calculated.

[0028]

(Equation 6)

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. At this time, it is advanced in the reactive power cutoff level q ₂ is negative. The advanced reactive power change amount calculating section 104 calculates the reactive power Qi detected by the reactive power detecting section 14 and
The difference between the cut-off level q ₂ (negative value when the proceeds) calculates Δ
qbi.

The reactive power accumulating section 110 has a delay reactive power Qi for the delay time t set by the settling section 20 and an input level q _1.
When the difference ΔQai becomes a positive value, or from the time when the difference between the reactive power Qi and cutoff level q ₂ ΔQbi is a negative value, by integrating the reactive power Qi is detected, the integrated value Qa,
Obtain Qb. However, when ΔQai continues to be a positive value, the integration is performed, but when the value becomes negative, the integration is stopped and the integrated value is set to 0. When ΔQbi continues to be a negative value, integration is performed. When ΔQbi becomes a positive value, integration is stopped and the integrated value is set to 0. When the delay time t has elapsed, the integrated values Qa and Qb are divided by the number of times of integration to obtain an average value ΔQ
a, ΔQb. Furthermore, the input capacitance Q _A by multiplying both transformation ratio r _1, r _2, to calculate the breaking capacity Q _B. Input capacity Q
_When the value of _A is positive, it is necessary to insert a capacitor close to that capacity. Therefore optimal capacitor capacity determination unit 120 one chooses from capacitor group that are currently blocked closest capacitor to the value of the input capacitance Q _A, corresponding to the capacitor and controls the driving unit 71 via the output state storage unit 60 Turn on the relay. When the capacitor of the capacitance close to the value of the input capacitance Q _A there are a plurality, it sends a control signal for making operation to select the capacitor is interrupted fastest previously therein. The value of the breaking capacity Q _B is when the negative is necessary to cut off the capacitor close to the capacity. Therefore optimal capacitor capacity determination unit 120 that controls the unit capacity Q driver 71 closest capacitance of the capacitor to a value via one select output state storage unit 60 of the _B from the capacitor group that are currently closed state Turn off the relay corresponding to the capacitor. Breaking capacity Q
_{When a} plurality of capacitors having a capacity close to the value of _B are in a turned-on state, a control signal for a shut-off operation is sent out by selecting the capacitor that was turned on earlier in the past.

Referring to the vector diagram of FIG. 4, when the load Pi = 150 kW, the minimum controllable negative Po = 15
Is charged capacity Q _A calculated so becomes equal to 0 kW 65
kvar. Since the nearest capacitor is C _2, the capacitor C ₂ is selected to ON. Isolation level Q ₂ this time is set as -10Kvar (advances). When the load Pi becomes 230 kW, the input capacity Q _A = 50 kvar is calculated, and the capacitor C ₄ is input. At this time, cutoff level Q ₂ is has a -10Kvar (advances). Load P
When i = 340 kW, the input capacity Q _A = 50 kvar is calculated. However, since the capacitor in the cut-off state is only 100 kVA, the capacitor C ₁ is input. In this case, cutoff level Q ₂ is because it is calculated from the minimum capacitance that are turned on, the Q ₂ = -10kvar (advances). At this time, the breaking capacity Q _B = 50 kvar is calculated, and the capacitor C _{2 that} has been initially supplied is cut off. Load Pi = 46
When becomes 0 kW, charged capacity 50kvar is calculated, the capacitor C ₂ is turned on. When the load Pi becomes 600 kW, the input level Q ₁ becomes
Calculated from equation (5), the delay is automatically set to 60 kvar.
At this time, the input capacity is calculated as 60 kvar. However, since there is only the capacitor C _{3 in the} cutoff state, this capacitor C ₃
Is input. When the capacitor C ₃ is charged, breaking capacity Q _B = 40kvar is calculated, among the capacitors 50kVA, C _4, which is applied first is cut off. Load Pi = 79
When becomes 0 kW, charged capacity 80kvar is calculated, the capacitor C ₄ is turned. Although not shown in FIG. 4, the same operation is performed when the load power decreases.

The display element driving section 86 of the display section 80 includes a leading / lagging number display 87, a unit display 88 and a light load display 81,
The delay indicator 82, the advance indicator 83, and the appropriate indicator 84 are driven. When the detected active power Pi is smaller than the minimum controllable load Po, the light load indicator 81 is turned on. Active power Pi
There controllable minimum load Po Beyond Moreover reactive power Qi is delayed when it exceeds the charged level q ₁ indicator 82 is lit, the display unit 83 proceeds when the reactive power Qi exceeds the cutoff level q ₂ to the advanced side Light. The reactive power Qi is the input level q
Appropriate indicator 84 is lit when it is between ₁ and cutoff level q _2. The numerical display 87 alternately displays numerical values of the current power factor and the reactive power of the power system in a cycle of 1 to 2 seconds based on output signals from the reactive power detector 14 and the power factor detector 15. At this time, the unit display of% and kvar is also turned on. The on-state display section 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 determination section 120 before the relay section 72 operates, and notifies the relay section 72 of the operation. Then, it turns on when turned on and turns off when shut off. Each setting of the operating condition setting unit 20 is configured to be easily operated by a digital switch, a touch panel, or the like.

[0033]

As described above, according to the present invention, since the capacitor closest to the amount of change in reactive power at the time of load change is turned on or off, the number of times of turning on and off is small, and the amount of reactive power after power factor improvement is reduced. Can be smaller. Further, since the capacity of the capacitor to be turned on or off is automatically calculated by the closing level calculating section and the closing level calculating section, setting of the operating condition is easy. In addition, the input level is automatically set so that the reactive power is constant in the low load area and the power factor is constant in the high load area according to the size of the load. Will not be. Further, since the cutoff level is automatically set, the operation is extremely easy.

[Brief description of the drawings]

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

FIG. 2 shows an operation curve diagram of FIG. 1, wherein (A) shows a reactive power Qik;
var diagram, (B) is a diagram of the total capacitance of the input capacitors Co kVA, (C) is a diagram of the reactive power Qkvar after power factor improvement, (D)
Indicates the capacity kVA of each of the capacitors C _{1 to} C ₄ , a circle indicates cut-off, and a black circle indicates turn-on and cut-off state diagram.

FIG. 3 is a block diagram of an automatic power factor adjusting apparatus according to another embodiment of the present invention.

4A and 4B are explanatory diagrams of the operation of FIG. 3, wherein FIG. 4A is an operation vector diagram, and FIG.

FIG. 5 is a block diagram of an automatic power factor adjusting apparatus showing a conventional example.

6 is a load diagram of FIG. 5, (A) is a diagram of active power Pi, and (B) is a diagram of delayed reactive power Qi.

FIG. 7 is an explanatory diagram of the operation of FIG. 5, where (A) shows a reactive power Qik;
var, (B) is a diagram of the total capacitance of the input capacitors Co kVA, (C) is a diagram of the reactive power Qkvar after power factor improvement, (D)
Indicates the capacity kVA of each of the capacitors C _{1 to} C ₄ , a circle indicates cut-off, and a black circle indicates turn-on and cut-off state diagram.

[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 80 Display part 101 Input level calculation part 102 Shutdown level calculation part 103 Delay reactive power Change amount calculation section 104 Advanced reactive power change amount calculation section 110 Reactive power integration section 120 Optimal capacitor capacity determination section 130 Input capacitor capacity storage section

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-47930 (JP, A) JP-A-62-285119 (JP, A) JP-A-63-198538 (JP, A) 280811 (JP, A) JP-A-63-198537 (JP, A) JP-A-55-112715 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G05F 1/70

Claims (2)

(57) [Claims] An automatic power factor adjusting apparatus for detecting reactive power of a power system and for turning on or off a phase-advancing capacitor based on the detection result to adjust a power factor of the power system. A voltage detecting unit for detecting a voltage by converting a voltage, a current detecting unit for detecting a current by converting a current of the power system, an active power detecting unit for detecting an active power from the detected voltage and the current, Reactive power detection unit for detecting reactive power from voltage and current, controllable target power factor after improvement of the power system, voltage transformation ratio of the voltage detection unit, current transformation ratio of the current detection unit, and capacity of the capacitor An operating condition setting unit that sets and stores operating conditions of a minimum load, an intermediate load, and an operation delay time, the target power factor, a voltage transformation ratio, a current transformation ratio, as the load of the power system increases or decreases.
Based on the minimum controllable load and the value of the active power detected by the active power detection unit, for a load having a size equal to or less than the intermediate load capacity value, the invalidity calculated from the intermediate load capacity and the target power factor. An input level calculation unit that calculates an input level so that the power factor is equal to or more than the target power factor for a load that is equal to or less than the value of the electric power and that exceeds the intermediate load capacity value. An input capacitor capacity storage unit that stores the capacity of the capacitor to be applied, an interrupt level calculation unit that calculates an interrupt level from the input level and the minimum value of the input capacitor capacity, and a delay reactive power that exceeds the input level to the delay side. A delay reactive power change amount calculating section for calculating a change amount, a leading reactive power change amount calculating section for calculating a lead reactive power change amount exceeding the cutoff level to the leading side, A reactive power integrating section for integrating the lag reactive power change amount or the leading reactive power change amount for the delay time set by the operating condition setting section and obtaining an average value thereof; the input level calculating section; the operating condition setting section; An optimum capacitor capacity determining unit that determines a capacitor to be applied from the capacitor capacity storage unit and the reactive power integrating unit, and determines a capacitor to be shut off from the shutoff level and the applied capacitor capacity storing unit and the reactive power integrating unit; An automatic power factor adjusting apparatus, comprising: an output unit having a drive unit for turning on or off the capacitor according to the determination of the determination unit; and an operation display unit for displaying the operation of each unit. 2. The automatic power factor adjusting apparatus according to claim 1 , wherein the phase-advancing capacitor includes a plurality of capacitors in different capacitance groups.
Der those with capacity equal groups capacitor is, when the closest equal volume of the capacitor to the average value calculated in the reactive power integration unit there are multiple past turned most when turned first from interruption of data An automatic power factor adjusting device, characterized in that the shut-off capacitor is turned on, and the shut-off capacitor is turned off when shut off.