Factor control system and factor control method

Abstract

To improve that, in power factor control using a phase advance capacitor, since capacity is determined for each phase advance capacitor and a power factor is controlled stepwise for each phase advance capacitor capacity in a case where the power factor control is performed by opening and closing operation of a switch on the primary side of the phase advance capacitor, the power factor can only be controlled in a state deviating from the target power factor, or there is possibility that the power factor becomes an advanced state, and installation space of the phase advance capacitor is also required.SOLUTION: A power factor control system includes: a power factor acquisition unit that acquires a power factor at a power reception point of a power consumer having an uninterruptible power supply device; the uninterruptible power supply device that variably supplies reactive power; and a control device that instructs the uninterruptible power supply device to supply the necessary reactive power based on the power factor at the power reception point acquired by the power factor acquisition unit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE Embodiments of the present invention relate to a power factor control system and a power factor control method. [Background technology]

[0002] Generally, the capacity of power generation equipment of electric power companies and equipment such as transformers in consumer's homes is based on apparent power, so it is necessary to prepare equipment that is larger than the power actually consumed (effective power). Therefore, electric power companies have implemented a policy of offering a certain discount on electricity charges for improving the power factor so that the apparent power on the consumer side becomes smaller.

[0003] Therefore, in order to improve the power factor at the receiving point, power consumers such as factory facilities often install power-leading capacitors 18a to 18d with a capacity of several tens to several hundreds of kVar in the receiving and transforming equipment as shown in Figure 8, and perform power factor control by opening and closing switches 17a to 17d on the primary side of the power-leading capacitors.

[0004] More specifically, Fig. 8 showing a conventional power factor control system shows a state in which the power factor calculated by power factor acquisition unit 15 is lower than the target power factor, so that a "close" instruction signal is sent from control device 30 to switches 17a and 17b (shown in black in the figure), and reactive power is supplied by leading-phase capacitors 18a and 18b. This state is shown in Fig. 9 as a vector diagram of AC power. In a state in which power factor control is not performed, that is, in which switches 17a to 17d are all open and reactive power is not supplied by leading-phase capacitors 18a to 18d, the apparent power is S1, the phase angle is θ1, and the reactive power is Q1 relative to active power P. In contrast, when power factor control is performed, that is, when a "close" command signal is sent to switches 17a and 17b (shown in black in the figure) and reactive power is being supplied by phase-leading capacitors 18a and 18b, the apparent power is S2, the phase angle is θ2, and the reactive power is Q3 relative to the active power P. It can be seen that the power factor is improved by reactive power Q2 (Q2=q1+q2) supplied from phase-leading capacitors 18a and 18b, and the apparent power S2 after power factor control is smaller than the apparent power S1 before power factor control.

[0005] However, in Figure 9, the reactive power from the phase-leading capacitors 18a and 18b does not satisfy a power factor of 1. Furthermore, when a "close" instruction signal is given to the switch 17c to supply reactive power q3 from the phase-leading capacitor 18c, the power factor becomes leading as shown by the dotted line in Figure 9, which is an apparent power S3.

[0006] Patent Document 1 describes an automatic power factor regulator that uses a leading-phase capacitor to adjust the power factor at the receiving point where power is received from high-voltage and extra-high-voltage systems, and describes technology that controls the power factor so that it does not become lagging if the target power factor is 1.

[0007] Patent Document 2 describes an uninterruptible power supply equipped with a converter that variably controls the input reactive power of the uninterruptible power supply. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2012-50289 A [Patent Document 2] JP 2011-55570 A Summary of the Invention [Problem to be solved by the invention]

[0009] As mentioned above, in power factor control using a leading-phase capacitor, the capacity of each leading-phase capacitor is fixed, and if the power factor is controlled by opening and closing the switch on the primary side of the leading-phase capacitor, the power factor is controlled in stages for each leading-phase capacitor capacity, so it may only be possible to control the power factor to a state that deviates from the target power factor, or the power factor may become leading. Also, installation space for the leading-phase capacitor is required.

[0010] Patent Document 1 describes a system that automatically controls the power factor using a leading-phase capacitor, and Patent Document 2 describes an uninterruptible power supply that is capable of power factor control, but does not describe a power factor control system that continuously controls the power factor to a target power factor for the entire power system on the consumer side, including the uninterruptible power supply. [Means for solving the problem]

[0011] Therefore, in order to solve the above problem, the power factor control system of an embodiment includes a power factor acquisition unit that acquires a power factor at a power receiving point of an electric power consumer having an uninterruptible power supply, an uninterruptible power supply that variably supplies reactive power, and a control device that instructs the uninterruptible power supply to supply the required reactive power based on the power factor at the power receiving point acquired by the power factor acquisition unit.

[0012] In addition, a power factor control method of an embodiment acquires a power factor at a power receiving point of an electric power consumer having an uninterruptible power supply, and when the power factor at the power receiving point is smaller than a predetermined value, the uninterruptible power supply, which variably supplies reactive power until the power factor at the power receiving point reaches the predetermined value, supplies lagging reactive power, and when the power factor at the power receiving point is greater than the predetermined value, the uninterruptible power supply supplies leading reactive power until the power factor at the power receiving point reaches the predetermined value. [Brief description of the drawings]

[0013] [Figure 1] Power factor control system according to the first embodiment [Diagram 2] Vector diagram of AC power in power factor control of the first embodiment [Diagram 3] 1 is a flowchart of a power factor control method according to a first embodiment. [Figure 4] Power factor control system according to a second embodiment [Diagram 5] Vector diagram of AC power in power factor control of the second embodiment [Figure 6] 1 is a flowchart of a power factor control method according to a second embodiment of the present invention; [Figure 7] Power factor control system according to the third embodiment [Figure 8] Conventional Power Factor Control System [Figure 9] Vector diagram of AC power in conventional power factor control DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] (First embodiment) A first embodiment of the invention will now be described with reference to the drawings.

[0015] A power factor control system according to this embodiment is shown in Fig. 1, and a vector diagram of AC power in the power factor control of this embodiment is shown in Fig. 2. Furthermore, a flowchart of the power factor control system according to this embodiment is shown in Fig. 3.

[0016] In the following description of the present embodiment, the predetermined target power factor is 1, but it may be another value, or may be a lagging or leading power factor less than 1. A power factor of 1 is ideal because it provides the best power consumption efficiency and does not require excessive equipment, but the predetermined target power factor may be a lagging or leading power factor less than 1 depending on the request of the power company or the convenience of the consumer.

[0017] The power factor control system in this embodiment will be described with reference to Fig. 1. Electric power is supplied to the entire facility via a connection point 10 to which electricity is supplied from a power company, a VCT 11 which is a watt-hour meter, and a special high-voltage transformer TR 12 which is a special high-voltage transformer. The supplied power is consumed by a plurality of pieces of equipment in the facility, such as loads 20a and 20b having a facility transformer 19. The power system in the facility is equipped with a plurality of uninterruptible power supplies UPS 22a to 22c, and power is supplied from the UPS 22a to 22c to highly sensitive equipment such as electronic devices and computers. Since the UPS 22a to 22c are connected to batteries, the configuration is such that even if power is lost for some reason, such as a power outage, the equipment can be prevented from stopping and data loss can be prevented for a short period of time.

[0018] Furthermore, the power factor control system in this embodiment calculates a power factor by inputting a voltage value passing through VT14, which is a voltage transformer from detection point 13, and a current value flowing through CT16, which is a current transformer, into power factor acquisition unit 15. Based on the calculated power factor, control device 30 calculates reactive power required to achieve a target power factor, and supplies the required reactive power from UPS 22a to 22c, which are uninterruptible power supplies.

[0019] The connection point 10 is the connection point between the power company and the power consumer when power is supplied from the power company, and generally refers to the location that is the starting point of the power supply to facilities that use power, such as homes, offices, factories, etc. Specifically, the transmission line or distribution line from the power company is connected to the connection point, and power is supplied from there to the facility.

[0020] The VCT11 is a combination of an instrument transformer and an instrument AC transformer, and is used to measure the amount of electric power.

[0021] The extra-high voltage TR12 is a special high voltage transformer that reduces the voltage to a voltage that can be used by the equipment within a facility when electricity is supplied from a power company at a so-called extra high voltage, such as 66kV. The extra-high voltage TR12 converts the extra high voltage electricity supplied from the power grid to a voltage that can be used by the equipment within the facility, for example from 66kV to 6.6kV, and supplies safe and appropriate electricity to the equipment in the facility.

[0022] The detection point 13 indicates a position on the system where a voltage for calculating a power factor is detected by the power factor acquisition unit 15. In this embodiment, the detection point 13 is the secondary side of the extra-high voltage TR 12, and measures a voltage stepped down by the extra-high voltage TR 12. Since the power factor at the detection point 13 is generally used as the power factor at the power receiving point, for convenience, in this embodiment, the detection point 13 is called the power receiving point.

[0023] VT14 is an instrument transformer that further reduces the voltage stepped down by TR12 for measurement by instruments. Even the voltage on the secondary side of TR12 is 6.6kV, for example, which is too high for instrument use. VT14 reduces 6.6kV to about 100V for instrument use.

[0024] The power factor acquisition unit 15 calculates a power factor by taking in the voltage that has passed through the VT 14, which is a voltage transformer, from the detection point 13 and the current that has been transformed by the CT 16, which is a current transformer. If the calculated power factor does not reach 1, which is a target power factor, the control device 30 calculates the amount of reactive power that will make the power factor 1, and instructs one or more of the UPSs 22a to 22c to supply reactive power.

[0025] The CT16 is an instrument current transformer that transforms currents of several hundred amperes to smaller currents, for example, around 5A. This is because equipment suited to currents of several hundred amperes would require large-scale equipment, which would entail huge costs. The CT16 contains primary (input) and secondary (output) coils, with the input power source connected to the primary coil and converted power output from the secondary coil. The current flowing on the primary side is transformed (reduced) to the secondary side based on the ratio of the number of turns of these coils.

[0026] The loads 20a and 20b are equipment within the facility, such as electric motors, mechanical equipment, lighting, etc. The appropriate voltage for each piece of equipment may differ, in which case the equipment transformer 19 steps down the voltage to an appropriate level and supplies power to each piece of equipment.

[0027] The UPS transformers 21a to 21c are input transformers for the UPSs 22a to 22c, and further step down the voltage of, for example, 6.6 kV stepped down by the extra-high voltage TR 12 to a voltage of 200V, 400V, or the like that can be used by the UPSs 22a to 22c.

[0028] The UPS 22a to 22c are so-called uninterruptible power supplies, and are connected to emergency batteries. The UPS 22a to 22c store power in the connected batteries, and can stably supply power even if the main power supply is temporarily lost or becomes unstable.

[0029] In addition, even if the waveform of the main power supply is unstable or noise or surges occur, the UPSs 22a to 22c can supply stable power using the built-in circuits and filters, allowing sensitive equipment such as electronic devices and computers to operate normally and preventing data loss and equipment failure.

[0030] In the UPS 22a to 22c in this embodiment, the converter is connected via a reactor, and the phase of the voltage generated by the converter is controlled, thereby enabling the phase of the current flowing through the reactor, i.e., the input power factor of the UPS to be controlled. This is not a stepwise control as in the case of using the phase-leading capacitors 18a to 18d in the conventional power factor control system (not ON / OFF of the phase-leading capacitors), but enables variable and continuous control within the capacity range of the UPS 22a to 22c.

[0031] For example, Fig. 1 shows a state in which the power factor calculated by the power factor acquisition unit 15 is lower than the target power factor, so that an instruction to supply reactive power is sent from the control device 30 to the UPSs 22a to 22c, and reactive power is supplied by the UPSs 22a to 22c. Fig. 2 shows this state as a vector diagram of AC power. In a state where power factor control is not performed, that is, a state in which reactive power is not supplied from the UPSs 22a to 22c, the apparent power is S1, the phase angle is θ1, and the reactive power is Q1 with respect to the active power P. In contrast, in a state where power factor control is performed, that is, a state in which reactive power Q4 is also supplied from the UPSs 22a to 22c, the apparent power S2 is the same as the active power P, and it can be seen that the power factor has been improved to 1.

[0032] In the power factor control system of the present embodiment, the calculated power factor is the power factor at the power receiving point, and by continuously controlling the power factor at the power receiving point using UPS 22a to 22c, it is possible to make the power factor closer to 1 than in conventional power factor control systems.

[0033] Next, a system flow of the power factor control method according to this embodiment will be described with reference to FIG.

[0034] First, the amount of power supplied to connection point 10 is measured by VCT 11, and then in this embodiment, the voltage is stepped down from 66 kV to 6.6 kV by extra high voltage TR 12. The electricity stepped down to 6.6 kV is further stepped down by VT 14 at detection point 13, and a voltage signal of the voltage is input to power factor acquisition unit 15 (S101). At the same time, a current signal of the current transformed by CT 16 is input to power factor acquisition unit 15 (S102).

[0035] Next, the power factor acquisition unit 15 calculates the power factor using the voltage and current measured as described above (S103). If the calculated power factor is 1 (Yes in S104), the system flow in this embodiment ends. If the calculated power factor is not 1 (No in S104), the control device 30 determines whether the power factor is lagging (S105).

[0036] If the power factor is not 1 (less than 1) and is lagging (Yes in S105), the control device 30 transmits a signal for leading power factor control to the UPSs 22a to 22c (S106). This may be to one or more of the UPSs 22a to 22c. The UPSs 22a to 22c that have received the signal for leading power factor control supply reactive power (lagging) (S107). When reactive power (lagging) is supplied, the system flow returns to steps S101 and S102 and is repeated.

[0037] If the power factor is not lagging, that is, if the power factor is leading (No in S105), the control device 30 transmits a signal for lagging power factor control to the UPSs 22a to 22c (S108). In this case, it may be to one or more of the UPSs 22a to 22c. The UPSs 22a to 22c that have received the signal for lagging power factor control supply reactive power (leading) (S109). When reactive power (leading) is supplied, the system flow returns to steps S101 and S102 and is repeated.

[0038] As described above, according to this embodiment, the following effects can be obtained.

[0039] The UPS 22a to 22c enable variable and continuous control, making it possible to control the power factor at the detection point 13, which is the power receiving point, to 1, and also reducing the installation space for a phase-leading capacitor.

[0040] Second Embodiment A second embodiment for carrying out the invention will now be described with reference to the drawings.

[0041] The power factor control system according to this embodiment will be described with reference to the power factor control system according to the second embodiment in FIG. 4, the vector diagram of AC power in the power factor control of the second embodiment in FIG. 5, and the flowchart of the power factor control method according to the second embodiment in FIG. 6. However, since the power factor control system according to this embodiment differs in part from the first embodiment, the same reference numerals as in the first embodiment are used for the components equivalent to those in the power factor control system according to the first embodiment, and the description thereof will be omitted.

[0042] As shown in Fig. 4, the power factor control system in this embodiment is a partial combination of the conventional power factor control system in Fig. 8 and the power factor control system in the first embodiment in Fig. 1. Depending on the operating conditions of the UPSs 22a to 22c, the reactive power supplied from the UPSs 22a to 22c may be limited, so this is a power factor control system in which the control device 30 can continuously control the power factor at the power receiving point by supplying reactive power by selecting the leading-phase capacitors 18a to 18d and supplying reactive power from the UPSs 22a to 22c which are uninterruptible power supplies.

[0043] The switches 17a to 17d are so-called switches that switch on / off the phase-leading capacitors 18a to 18d. For example, when the switch 17a is in the "on" state, the switch 18a is connected to the system, and reactive power is supplied from the switch 18a.

[0044] By supplying reactive power from the phase-leading capacitors 18a to 18d, the power factor at the power receiving point can be improved.

[0045] For example, in Fig. 4, since the power factor calculated by the power factor acquisition unit 15 is lower than the target power factor, the control device 30 sends an "on" instruction signal to the switches 17a and 17b (shown as black in the figure), reactive power is supplied by the leading-phase capacitors 18a and 18b, and reactive power is also supplied from the UPSs 22a to 22c. This state is shown in Fig. 5 as a vector diagram of AC power. In a state where power factor control is not performed, that is, all of the switches 17a to 17d are in an open state, reactive power is not supplied by the leading-phase capacitors 18a to 18d, and reactive power is not supplied from the UPSs 22a to 22c, the apparent power is S1, the phase angle is θ1, and the reactive power is Q1 with respect to the active power P. In contrast, when power factor control is performed, that is, when an instruction signal to "close" is sent to switches 17a and 17b (shown in black in the figure), reactive power Q2 (q1+q2) is supplied by phase-leading capacitors 18a and 18b, and reactive power Q4 is also supplied from UPSs 22a to 22c, the apparent power S2 is equal to active power P, and it can be seen that the power factor has been improved to 1.

[0046] Next, a system flow of the power factor control method according to this embodiment will be described with reference to FIG.

[0047] First, the amount of power received at connection point 10 is measured by VCT 11, and then in this embodiment, the voltage is stepped down from 66 kV to 6.6 kV by extra high voltage TR 12. The electricity stepped down to 6.6 kV is further stepped down by VT 14 at detection point 13, and a voltage signal of the voltage is input to power factor acquisition unit 15 (S201). At the same time, a current signal of the current transformed by CT 16 is input to power factor acquisition unit 15 (S202).

[0048] Next, the power factor acquisition unit 15 calculates the power factor using the voltage and current measured as described above (S203). If the calculated power factor is 1 (Yes in S204), the system flow in this embodiment ends. If the calculated power factor is not 1 (No in S204), the control device 30 determines whether the power factor is lagging (S205).

[0049] If the power factor is lagging (Yes in S205), the control device 30 judges whether the supply amount of reactive power required to improve the power factor to 1 is greater than the capacity of one leading-phase capacitor (S206). If the supply amount of reactive power required to improve the power factor to 1 is greater than the capacity of one leading-phase capacitor (Yes in S206), the control device 30 outputs, for example, an instruction signal to "close" the switches 17a and 17b (S207). The switches 17a and 17b that have received the instruction signal to "close" are closed, and reactive power (lagging) is supplied from the leading-phase capacitors 18a and 18b (S208). When reactive power (lagging) is supplied, the system flow returns to steps S201 and S202 again and is repeated.

[0050] In the determination of S206, if the supply amount of reactive power required to improve the power factor to 1 is smaller than the capacity of one leading phase capacitor (No in S206), the control device 30 transmits a leading power factor control signal to the UPSs 22a to 22c (S209). This enables continuous and variable power factor control, and the power factor can be brought closer to 1. This may be done for any one or more of the UPSs 22a to 22c. The UPSs 22a to 22c that have received the leading power factor control signal supply reactive power (lagging) (S210). When reactive power (lagging) is supplied, the system flow returns to steps S201 and S202 again and is repeated.

[0051] When the power factor is not lagging, that is, when the power factor is leading (No in S205), the control device 30 judges whether or not the supply amount of reactive power that is unnecessary for improving the power factor to 1 is larger than the capacity of one leading-phase capacitor (S211). When the supply amount of reactive power that is unnecessary for improving the power factor to 1 is larger than the capacity of one leading-phase capacitor (Yes in S211), the control device 30 checks whether or not a switch is closed (S212). When a switch is closed (Yes in S212), the control device 30 outputs an instruction signal to "open" the switch (S212). When multiple switches are closed, the control device 30 outputs an instruction signal to "open" one of the switches. In this embodiment, for example, when both the switches 17a and 17b are closed, the control device 30 outputs an instruction signal to "open" one of the switches 17a and 17b (S213). When either of the switches 17a, 17b receives the "open" instruction signal and opens, the supply of reactive power (lag) from either of the leading-phase capacitors 18a, 18b is stopped (S214). When the supply of reactive power (lag) is stopped, the system flow returns to steps S201 and S202 and is repeated.

[0052] In the determination of S211, if the supply amount of reactive power that is unnecessary for improving the power factor to 1 is smaller than the capacity of one leading phase capacitor (No in S211), a signal for lagging power factor control is sent to the UPSs 22a to 22c (S215). In this case, it may be sent to one or more of the UPSs 22a to 22c. The UPSs 22a to 22c that have received the signal for lagging power factor control supply reactive power (leading) (S216). When reactive power (leading) is supplied, the system flow returns to steps S201 and S202 again and is repeated.

[0053] Also, in the determination in S212, if no switch is closed (No in S212), the flow is the same as the flow from S215 onwards described above.

[0054] As described above, according to this embodiment, the following effects can be obtained.

[0055] By combining the stepwise power factor control by 18a to 18d and the variable and continuous control by UPS 22a to 22c, it becomes possible to control the power factor at detection point 13, which is the power receiving point, to 1, regardless of the operating status of UPS 22a to 22c.

[0056] (Third embodiment) Hereinafter, a third embodiment for carrying out the invention will be described with reference to the drawings.

[0057] The power factor control system according to this embodiment will be described with reference to the power factor control system in FIG. 7. Since the diagnostic system according to this embodiment differs in part from the first embodiment, the same reference numerals as in the first embodiment are used for the components equivalent to those in the diagnostic system according to the first embodiment, and the description thereof will be omitted.

[0058] The power factor control system in this embodiment is obtained by adding a target power factor setting device 23 to the power factor control system in the first embodiment.

[0059] 7, the target power factor setting device 23 transmits a target power factor to the control device 30 via a network. For example, communication may be performed using a communication method such as a wireless LAN (Local Area Network), a wired LAN, Bluetooth (registered trademark), or LTE (Long Term Evolution) (registered trademark).

[0060] The target power factor setting device 23, for example, obtains a power factor requested by an external power company or the like, automatically sets it as a target power factor, and transmits it to the control device 30. It is also possible to manually set an arbitrary target power factor. This target power factor is set to a power factor of 1 or more or a power factor of less than 1, regardless of the actual power factor at the detection point 13, which is the power receiving point.

[0061] As described above, according to this embodiment, the following effects can be obtained.

[0062] By automatically setting the power factor requested by an external power company, etc. as the target power factor, it is possible to respond quickly and flexibly to requests from systems outside the facility, and it can be used as a power factor adjustment device for power systems.

[0063] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0064] 10...Connection point, 11...VCT, 12...Extra-high-voltage TR, 13...Detection point (power receiving point), 14...VT, 15...Power factor acquisition unit, 16...CT, 17a, 17b, 17c, 17d...Switch, 18a, 18b, 18c, 18d...Leading-phase capacitor, 19...Load transformer, 20a, 20b...Load, 21a, 21b, 21c...UPS transformer, 22a, 22b, 22c...UPS, 23...Target power factor setting device, 30...Control device, P...Active power, S1...Apparent power before power factor improvement, S2...Apparent power after power factor improvement, θ1...Phase angle before power factor improvement, θ2...Phase angle after power factor improvement, Q1...Reactive power before power factor improvement, Q2...Reactive power by leading-phase capacitor, Q3...Reactive power after power factor improvement, Q4...Reactive power by UPS

Claims

1. a power factor acquisition unit that acquires a power factor at a power receiving point of a power consumer having an uninterruptible power supply; An uninterruptible power supply that variably supplies reactive power; A control device that instructs the uninterruptible power supply to supply necessary reactive power based on the power factor of the power receiving point acquired by the power factor acquisition unit; A power factor control system comprising:

2. At least one leading-phase capacitor for supplying reactive power; The control device controls the power factor at the power receiving point by supplying reactive power by selecting the leading-phase capacitor and supplying reactive power from the uninterruptible power supply device.

2. The power factor control system of claim 1.

3. Further comprising a target power factor setting device that acquires a power factor at the power receiving point required from the outside and transmits it to the control device; 3. The power factor control system according to claim 1 or 2.

4. Obtaining a power factor at a receiving point of a power consumer having an uninterruptible power supply; When the power factor at the power receiving point is smaller than a predetermined value, an uninterruptible power supply that variably supplies reactive power until the power factor at the power receiving point becomes the predetermined value supplies lagging reactive power; When the power factor at the power receiving point is greater than a predetermined value, the uninterruptible power supply supplies leading reactive power until the power factor at the power receiving point reaches the predetermined value. Power factor control methods.

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