JP2012050290A - Automatic power factor regulator - Google Patents

Abstract

[PROBLEMS] An automatic phase-adjusting capacitor opening / closing control without assuming the load power factor in advance, and without re-estimating the load power factor even when the load equipment is replaced or expanded. Provide a power factor regulator.
An effective value calculation unit for calculating an effective value of a current on a load side from a power receiving point, a closing / opening determination control unit for controlling a closing / opening state of a switch, and a closing / opening determination control unit The load power factor of the load is calculated by using the current effective value calculated by the effective value calculation unit before and after the opening or opening of the phase-advancing capacitor that is controlled to open, and the rated current value of the phase-advancing capacitor that has been turned on or released. A load power factor estimation unit for obtaining an estimated value.
[Selection] Figure 1

Description

  The present invention relates to an automatic power factor adjuster for electric power consumers, which performs input / release control of a phase advance capacitor installed by an electric power consumer for load power factor improvement.

  The power factor of the power receiving point of the power consumer (sometimes simply referred to as the customer) receiving power from the high voltage system and the extra high power system is generally in the lagging direction (reactive power consumption), improving the power factor of the power receiving point There is a power factor discount system that makes basic charges cheaper. Since power factor deterioration in the forward direction (generating reactive power) is allowed, many customers install a phase advance capacitor to improve the power factor at the power receiving point in the forward direction.

  If the phase-advancing capacitor is always connected, even if the power factor is properly compensated to around 100% at heavy load, it will be overcompensated at light load, that is, extreme advance power factor, and power in the customer premises system and commercial power system This increases the loss and causes adverse effects such as unnecessarily increasing the system voltage. Therefore, as a general measure for constantly maintaining the power receiving point power factor close to 100%, there is a phase-advancing capacitor input / release control device, that is, an automatic power factor adjuster.

  The current automatic power factor adjuster measures the reactive power passing through an installation location such as a power receiving point, and determines the on / off state of one or more phase-advancing capacitors so that the value approaches zero. In order to measure passing reactive power, it is necessary to install both a voltmeter and an ammeter, and to calculate the reactive power value from the instantaneous value of both measuring instruments. This increases the cost of the automatic power factor regulator. Yes.

  In order to simplify the configuration of the automatic power factor adjuster, in Patent Document 1, instead of measuring the passing reactive power, only the current is simply measured, and when the current increases beyond the set value, the phase advance capacitor is set. The phase-advancing capacitor is opened at the time when it is reduced to less than that. However, in this method, it is necessary to assume the on-site load power factor of the customer in advance. If the assumption of the on-site load power factor is different from the actual situation, the charging / discharging control of the phase advance capacitor is not performed properly, and the power receiving point power factor is slightly advanced or delayed.

  Therefore, in Patent Document 2, the load power factor is input in advance, the phase advance capacitor capacity is converted into a current value based on the load power factor, the current value is compared with the measured load current, and the phase advance capacitor is turned on.・ We decide to open.

Japanese Utility Model Publication No. 6-70447 Japanese Patent Laid-Open No. 11-353044

  Automatic power factor regulators that control the input and release of phase-advancing capacitors only by current measurement are simpler and less expensive than automatic power factor regulators that measure reactive power directly, but load power is required in advance. It is necessary to appropriately estimate the rate. However, in reality, the power factor characteristics of individual load devices are not necessarily specified in specifications or catalogs, and it has been difficult to presume the load power factor of the entire premises including them. In addition, when the load equipment is replaced or expanded, it is necessary to re-estimate the load power factor.

  The present invention was made to solve the problems of the conventional automatic power factor regulator as described above. In the automatic power factor regulator that controls the opening and closing of the phase advance capacitor only by current measurement, the load power An automatic power factor regulator that can perform appropriate phase-advancing capacitor on / off control without assuming the rate in advance, and without assuming the load power factor again even if the load equipment is replaced or expanded. The purpose is to provide.

  The present invention is an automatic power factor regulator that controls connection of a phase advance capacitor for power factor improvement provided to be connected in parallel with this load on the load side from the power receiving point of a power consumer by a switch. The effective value calculation unit that calculates the effective value of the current on the load side from the power receiving point, the on / open determination control unit that controls the on / off state of the switch, and the on / open determination control unit Obtain the estimated load power factor of the load using the effective current value calculated by the effective value calculation unit before and after the phase-advancing capacitor is turned on or opened, and the rated current value of the phase-advanced capacitor that is turned on or released. And a load power factor estimation unit.

  According to the present invention, it is possible to perform appropriate phase-advanced capacitor on / off control without assuming the load power factor in advance and without assuming the load power factor again even when the load equipment is replaced or expanded. Automatic power factor adjuster that can

It is a block diagram which shows the customer premise system | strain containing the automatic power factor regulator by Embodiment 1 of this invention. It is a flowchart which shows the processing flow of the principal part of the automatic power factor regulator by Embodiment 1 of this invention. It is a conceptual diagram which shows the calculation method of the load power factor in the automatic power factor regulator by Embodiment 1 of this invention. It is a block diagram which shows the customer premises system containing the automatic power factor regulator by Embodiment 2 of this invention. It is a flowchart which shows the processing flow of the principal part of the automatic power factor regulator by Embodiment 2 of this invention. It is a conceptual diagram which shows another calculation method of the load power factor in the automatic power factor regulator by Embodiment 2 of this invention. It is a block diagram which shows the customer premises system containing the automatic power factor regulator by Embodiment 3 of this invention. It is a flowchart which shows the processing flow of the principal part of the automatic power factor regulator by Embodiment 3 of this invention.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a customer premises system including an automatic power factor adjuster 1 according to Embodiment 1 of the present invention. Since the power consumer subject to power factor discount is three-phase power reception, it is also shown in FIG. 1 as a three-phase circuit. In a three-phase circuit extending from the power receiving point 2 to the premises, the phase advance capacitor 3 is a facility for canceling the reactive power component of the load and improving the power receiving point power factor, and is turned on and off according to the size of the load A switch 4 is provided for this purpose. As shown in FIG. 1, one or more phase-advancing capacitors 3 are usually installed on the load side near the power receiving point 2 or on the secondary side of a transformer (not shown) on the load side.

  On the power receiving point side of the installation point 5 of the phase advance capacitor 3, ammeters (CT) CT1 and CT2 for grasping the magnitude of the load are installed as representative phases (the R phase is a representative phase in the figure). For customers with a large load three-phase imbalance, an example in which the CT number is installed in addition to the representative phase is also conceivable. In FIG. 1, the ammeter CT1 measures only the load current, and the ammeter CT2 measures a current obtained by combining (vector sum) the load current and the current of the phase advance capacitor 3 being turned on.

  The automatic power factor adjuster 1 converts the instantaneous current values measured by the phase advance capacitor DB11 and the ammeters CT1 and CT2 into effective values at any time, and stores the respective capacities of one or more installed phase advance capacitors. The phase-advancing capacitor 3 is turned on when the effective value measured by the ammeter CT1 exceeds a predetermined threshold value, and the phase-advancing capacitor 3 is opened when the effective value is lowered. At any time when the opening determination control unit 13 and the phase advance capacitor 3 are turned on, the current effective values of the ammeters CT1 and CT2 and the current phase advance capacitor capacity are set to the phase advance capacitor DB (database) 11. The load power factor estimating unit 14 for estimating the load power factor and the threshold updating unit 15 for updating the threshold current for turning on / off the phase advance capacitor based on the estimated load power factor are provided.

  FIG. 2 is an example of a processing flowchart of the load power factor estimation unit 14 and the threshold update unit 15 in the automatic power factor adjuster 1 in the configuration of FIG. The other effective value calculation unit 12 is configured by a general circuit or the like, and has a function of converting an instantaneous value measurement value into an effective value. The on / off determination control unit is a current calculation unit 12. The effective current value of the ammeter CT1 converted by the above is constantly monitored, and when the effective current value is equal to or greater than the threshold value, a predetermined capacitor is inserted, and when the current effective value is equal to or less than the threshold value, the opening is controlled.

  The flow in FIG. 2 is performed at a fixed interval of a predetermined interval such as 1 hour. First, it is determined whether or not there is a phase advance capacitor that is currently turned on (ST1), and if not, the process ends. If there is a phase advance capacitor being turned on, the current effective value Ia of the ammeter CT1 and the current effective value Ib of the ammeter CT2 calculated by the effective value calculation unit 12 are fetched (ST2). At the same time, each rated current value of the phase advance capacitor that is currently turned on is taken in from the phase advance capacitor DB11, and the sum Ic is calculated (ST3).

Next, the load power factor is calculated from Ia, Ib, and Ic (ST4). FIG. 3 is a conceptual diagram of a method for calculating the load power factor. FIG. 3 shows an example of turning on the first phase advance capacitor. Ia corresponds to the current value at power receiving point 2 before turning on the phase advance capacitor, and Ib corresponds to the current value at power receiving point 2 after turning on. Ic is a rated current value obtained by converting a capacitance C (kVar) of the phase advance capacitor into a current value based on the rated voltage V (kV). For example, in a three-phase circuit, it can be calculated as follows.
Ic = C / (V × √3)
Here, this Ic itself may be stored as data in the phase advance capacitor DB11. In this case, step ST3 is a procedure of “reading the rated current value from the phase advance capacitor DB11”.

The reactive power component of the load is generally in the lag direction. When the phase advance capacitor is inserted, the reactive power component with the phase advance capacitor changed from Ia to Ib in the advance direction as shown in FIG. Assuming that the phase of the load current is θ (based on the voltage), the load power factor F _L is F _L = cos θ.
Is defined as

（１）
となる。負荷力率Ｆ_Ｌは

（２）
と算定でき、負荷力率Ｆ_Ｌの推定値が得られる。 Considering a right triangle with the long side of Ib in FIG. 3 and the short sides of the two directions of “current effective branch axis” and “current invalid branch axis”, the following equation is established from Pythagorean's theorem.
(Ic−Ia · sin θ) ² + (Ia · cos θ) ² = Ib ²
Expand the left side and replace it with the formula of sinθ
Ia ² (sin ² θ + cos ² θ) −2 · Ia · Ic · sin θ + Ic ² = Ib ²
Ia ² −2 · Ia · Ic · sin θ + Ic ² = Ib ²
Become

(1)
It becomes. The load power factor _FL is

(2)
And it can be calculated, the estimated value of load power factor F _L is obtained.

となる。２台目以降の閾値Ｉｎは、

とすれば良い。このようにして、負荷力率Ｆ_Ｌを推定する毎に、進相コンデンサの各段（各台目）の閾値電流を更新する（ＳＴ５）。 Thus sinθ in load power factor F _L and 3 is estimated, it is possible to threshold setting of phase advancing capacitor from the current effective value of the measured current. For example, when it is desired to maintain the power reception point power factor close to 100%, in FIG. 3, sinθ in the equation (1) is added to the measured current effective value Ia of the ammeter CT1.
What is necessary is just to set a threshold value so that the value multiplied by may be half of the first capacitor rated current Ic1. In other words, the threshold I1 for turning on / off the first phase advance capacitor is

It becomes. The threshold value In for the second and subsequent units is

What should I do? In this manner, each of estimating the load power factor F _L, and updates the threshold current of each stage of the phase advancing capacitor (individual car th) (ST5).

Estimates and the load power factor F _L of formula (2), sin [theta of formula (1) is not determined only by a single calculated value, taking the average value of a plurality of times calculated value, further improvement in the estimation accuracy Can be expected.
As described above, according to the first embodiment, it is possible to estimate the load power factor only by measuring the current without directly measuring the reactive power, and it is possible to appropriately control the phase advance capacitor.

Embodiment 2. FIG.
FIG. 4 is a block diagram showing the automatic power factor adjuster 1 and the customer premises system according to Embodiment 2 of the present invention. 4, the same reference numerals as those in FIG. 1 denote the same or corresponding parts. In the second embodiment, the ammeter CT1 provided on the load side from the installation point 5 of the phase advance capacitor 3 in the first embodiment shown in FIG. 1 is omitted, and the current change before and after the phase advance capacitor is turned on is measured by the ammeter CT2. The other configurations are the same.

  FIG. 5 is an example of a processing flowchart of the closing / opening determination control unit 13, the load power factor estimation unit 14, and the threshold update unit 15 in the automatic power factor adjuster 1 in the configuration of FIG. 4. The effective value calculator 12 is a general circuit that converts the instantaneous value measurement value of the ammeter CT2 into an effective value, as in the first embodiment.

  The flow in FIG. 5 is performed at a high-speed constant cycle such as 1 second. First, the current effective value Ia of the ammeter CT2 converted by the effective value calculation unit 12 is taken in (ST1), and when the threshold value stored in the automatic power factor adjuster is exceeded, the phase advance capacitor is inserted and lowered. If so, the phase advance capacitor is opened (ST12 to ST15). When there are a plurality of (for example, n) phase advance capacitors, there are a plurality (n stages) of threshold values for each phase advance capacitor.

  If the change in the local load is small and the threshold value is not newly exceeded or decreased, the process is terminated as it is (ST14). If the phase advance capacitor is turned on / off, the current value after turn on / off measured by the ammeter CT2 is further taken in (ST16), and the phase advance capacitor rated current that has been turned on / off is calculated. (ST17), the load power factor is estimated (ST18).

  The load power factor estimation method is the same as in the first embodiment. When the first phase advance capacitor is turned on, the current effective value Ia (= load current) before turning on the phase advance capacitor, the current effective value Ib after turning on the phase advance capacitor, and the rated current Ic of the inputted phase advance capacitor The relationship is the same as in FIG. 3 described in the first embodiment, and the load power factor is calculated by the same calculation formula as the formula (2) in the first embodiment.

によって求める。cosδが求まれば、sinδも自動的に求まる。 FIG. 6 shows the current effective value Ia before turning on the phase advance capacitor, the current effective value Ib after turning on, and the turn on when one or more phase advance capacitors have already been turned on and the second and subsequent phase advance capacitors are turned on. It shows the relationship between the rated current Ic of the phase advance capacitor, the load current effective value Ie, and the rated current value If of the phase advance capacitor that has already been turned on. In this case as well, the phase δ is set in the same manner as in FIG.

Ask for. If cosδ is obtained, sinδ is also automatically obtained.

となる。従って負荷力率Ｆ_Ｌは、

によって、求めることができる。 To determine the load power factor F _L is the long side of the Ia, focusing on a right triangle with the shorter sides lying in two directions as "current active component axis" a "current reactive component axis", the Pythagorean theorem,
(If + Ia · sin δ) ² + (Ia · cos δ) ² = Ie ²

It becomes. Therefore, the load power factor _FL is

Can be obtained.

  In the above example of obtaining the estimated value of the load power factor, the case where the phase advance capacitor is inserted has been described as an example. However, the case where the phase advance capacitor is opened can be obtained in the same manner. When the circuit is opened, the load power factor and the like can be obtained by the same equation as above, where Ib in the above equation is the current before the phase advance capacitor is opened and Ia is the current after the phase advance capacitor is opened.

Thus to update the threshold current of each stage of the phase advancing capacitor, using load power factor F _L that is estimated (ST19). The estimated load power factor is reflected on the threshold value in the same manner as described in the first embodiment. Further, the estimated value of the load power factor is not determined only by the calculated value of the result of turning on and off the capacitor once, and if the average value is taken a plurality of times, the estimation accuracy can be further improved.

Embodiment 3 FIG.
FIG. 7 is a block diagram showing an automatic power factor adjuster 1 and a customer premises system according to Embodiment 3 of the present invention. 7, the same reference numerals as those in FIGS. 1 and 4 denote the same or corresponding parts. The third embodiment is the same as the second embodiment except that a fixed cycle insertion / release instruction unit 16 is added to the automatic power factor adjuster.

  FIG. 8 is an example of a processing flowchart of the fixed cycle input / release instruction unit 16, the input / release determination control unit 13, the load power factor estimation unit 14, and the threshold update unit 15 in the automatic power factor adjuster in the configuration of FIG. is there. The flow in FIG. 8 is performed at a regular cycle, for example, 3 hours. First, it is determined whether or not the phase-advancing capacitor charging / discharging control by the charging / discharging determination control unit 13 has been performed as shown in the processing flow of FIG. (ST21) If the control has been performed, the process ends (ST21).

If control is not performed, phase-advancing capacitor on / off control is performed to determine the load power factor regardless of whether or not the load has changed. First, the current effective value of the ammeter CT2 before being turned on is taken in (ST22), and then, the turning-on control of the next stage is instructed and turned on (ST23). The current effective value of the ammeter CT2 after the charging is taken in (ST24), and then the phase-advancing capacitor at the next stage that has been input is opened to return the connection state of the phase-advancing capacitor to the original state. Here, the input / release control target is a “next stage capacitor” that has not been turned on at that time (for example, if the first stage has already been turned on, the second stage is “the next stage capacitor”). Become). The processing (ST17 to ST19) after turning on / opening the phase advance capacitor is the same as in FIG. 5 of the second embodiment. That is, the rated current of the next day of the capacitor which supplied as Ic (ST17), to estimate the load power factor F _L (ST18), updates the threshold current of the capacitor of each stage using the estimated load power factor ( ST19).

In the above description, the phase-advancing capacitor is inserted for grasping the load power factor. However, the phase-advancing capacitor that has already been input is temporarily opened, the effective current value before and after the opening, and the rated current of the phase-advancing capacitor. Needless to say, the estimated value of the load power factor can be obtained from the value as described in the second embodiment.
Further, the average value of the estimated values of the load power factor for a plurality of times may be determined as the estimated value of the load power factor, and further improvement in estimation accuracy can be expected.

  According to the third embodiment, even when the number of phase-advancing capacitors being charged / released is small, the next-stage phase-advancing capacitor is charged / released on a trial basis, and the load power factor can be grasped. In addition, since the phase-advancing capacitor at the next stage is opened and then immediately opened, the effect on the power loss and the power factor discount of the customer can be almost ignored. Furthermore, since it is applied when the number of phase-advancing capacitors is small, the effect on the life of the switch is small.

1: Automatic power factor adjuster 2: Power receiving point 3: Phase advance capacitor 4: Switch 12: Effective value calculation unit 13 Input / release determination control unit 14: Load power factor estimation unit 15: Threshold update unit

Claims (4)

In the automatic power factor regulator that controls the connection of the phase advance capacitor for power factor improvement provided to be connected in parallel with this load on the load side from the power receiving point of the power consumer,
An effective value calculation unit for calculating the effective value of the current on the load side from the power receiving point,
An on / off determination control unit for controlling the on / off state of the switch;
The effective current value calculated by the effective value calculation unit and the rated current of the advanced phase capacitor that has been input or released before and after the input or release of the phase advance capacitor controlled by the input / release determination control unit. A load power factor estimator that calculates an estimated value of the load power factor of the load using a value;
An automatic power factor adjuster characterized by comprising:   The phase-advancing capacitor is periodically switched on or off, and the load power factor is calculated using the effective current value before and after the phase-advancing capacitor is switched on or off, and the rated current value of the phase-advancing capacitor that has been switched on or opened. The automatic power factor adjuster according to claim 1, wherein an estimated value is obtained.   The load power factor estimator is characterized in that an average value of a plurality of estimated values of a plurality of load power factors estimated during a plurality of times of phase advance capacitor insertion or release control is an estimated value of the load power factor. The automatic power factor adjuster according to 1 or 2.   Threshold update unit that calculates and updates the threshold for determining the input / release of the phase advance capacitor for power factor improvement using the load power factor estimated by the load power factor estimation unit in the input / release determination control unit The automatic power factor adjuster according to any one of claims 1 to 3, further comprising:

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