Apparatus control system

Abstract

To provide an apparatus control system that can improve energy saving effect compared to a configuration in which an inverter or other device is connected in series between the apparatus and a power source.SOLUTION: An apparatus control system includes an apparatus 1 that is operated at rated output or at suppressed output, a power source 2 that supplies AC power to the apparatus 1, and a reactive power compensator 3 that is connected in parallel with the apparatus 1 to the power source 2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a device control system that controls the operation of a device. [Background technology]

[0002] Conventionally, as described in, for example, Patent Documents 1 and 2 below, there has been known a system in which an inverter or a voltage control unit (hereinafter referred to as "inverter, etc.") is connected in series between a power source and an apparatus that is operated with suppressed output (see FIG. 10(a) of the present application). In FIG. 10(a), the inverter, etc. is written as INV. In addition, as described in, for example, Non-Patent Document 1 below, there has been a trend to replace standard efficiency motors (IE1) with expensive high efficiency motors (IE3) (see FIG. 10(b) of the present application). These inverters, etc. and high efficiency motors can save energy (reduce power consumption). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-175226 [Patent Document 2] Japanese Patent Application Publication No. 6-261594 [Non-patent literature]

[0004] [Non-Patent Document 1] "Top Runner Motors for Global Environmental Protection and Energy Conservation," published by the Japan Electrical Manufacturers' Association, November 2021 Summary of the Invention [Problem to be solved by the invention]

[0005] In the case of a configuration in which an inverter or the like is connected in series between the device and the power supply as shown in Fig. 10(a), the following concerns arise. That is, the current flowing through the device itself flows through the inverter, etc., so a large power loss occurs in the inverter, etc., reducing the energy-saving effect. Also, if the inverter or the like breaks down, the system must be stopped for major repairs, which is very troublesome.

[0006] In the case of a configuration using a high-efficiency motor (IE3) as shown in (b) of Figure 10, the system cost increases. Also, in a system in which a standard efficiency motor (IE1) is already installed, the task of replacing the standard efficiency motor (IE1) with a high efficiency motor (IE3) is cumbersome.

[0007] The present invention has been made to solve the above-mentioned problems, and one of its objects is to provide a device control system that can solve at least one of the problems associated with the conventional configurations described above. [Means for solving the problem]

[0008] The present inventors have found that at least one of the problems of the conventional configuration as described above can be solved by connecting a static var compensator in parallel with the equipment to the power source. The present invention was made based on this new finding.

[0009] [1] In one embodiment, the present invention relates to an equipment control system including an equipment that is operated at a rated voltage or at a reduced output, a power source that supplies AC power to the equipment, and a reactive power compensation device that is connected in parallel with the equipment and to the power source.

[0010] [2] The present invention may relate to the equipment control system according to claim 1, wherein the reactive power compensation device is a Static Var Generator (SVG) device.

[0011] [3] The present invention may relate to an equipment control system as described in paragraph 2, wherein the SVG device has an inverter, a capacitor connected between the positive and negative busbars of the inverter, and a coil connected to each of the AC output terminals of the inverter.

[0012] [4] The present invention may relate to an equipment control system described in any one of claims 1 to 3, wherein the rated operation is operation within a range of ±10% of the rated output.

[0013] [5] The present invention may relate to an equipment control system according to any one of claims 1 to 4, wherein the output suppression operation is operation within a range of 10% or more and less than 90% of the rated output.

[0014] [6] The present invention may relate to an equipment control system according to any one of claims 1 to 5, wherein the fluctuation range of the output of the equipment per second is 20% or less.

[0015] [7] The present invention may relate to an equipment control system according to any one of claims 1 to 6, further comprising a control device that monitors the power consumption of the equipment and causes the reactive power compensation device to change the voltage applied to the equipment so that the power consumption of the equipment is reduced.

[0016] [8] The present invention may relate to an equipment control system according to any one of claims 1 to 7, further comprising a reactor inserted in series between the equipment and the power source.

[0017] [9] The present invention may relate to an equipment control system as described in claim 8, wherein the reactor generates a voltage drop of more than 0% and not more than 30% of the power supply voltage.

[0018]

[10] The present invention may relate to the equipment control system described in paragraph 8 or 9, wherein the equipment includes a first equipment and a second equipment connected in parallel to the power source, the first equipment has a voltage at which power consumption is at a minimum different from that of the second equipment, and the reactor is inserted in series between the first equipment and the power source.

[0019]

[11] The present invention may relate to an equipment control system according to any one of claims 1 to 10, wherein the equipment is a motor equipment or a heater. Effect of the Invention

[0020] According to one embodiment of the device control system of the present invention, at least one of the problems associated with the conventional configuration can be resolved. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is an explanatory diagram illustrating a device control system according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is an explanatory diagram showing a method of operating the pump in FIG. [Diagram 3] FIG. 2 is an explanatory diagram showing a first modified example of the device control system of FIG. [Figure 4] 1. FIG. 4 is an explanatory diagram showing a second modified example of the device control system of FIG. [Diagram 5] FIG. 2 is a circuit diagram showing the reactive power compensation device of FIG. 1 in more detail. [Figure 6] FIG. 2 is a block diagram showing a control block of an SVG device. [Figure 7] 6 is an equivalent circuit diagram when a load voltage Vo is controlled using the reactor (coil) and SVG device of FIG. 5, and a vector diagram showing how the load voltage Vo changes depending on the coil impedance jωL and the output current of the SVG device. [Figure 8] FIG. 6 is a circuit diagram showing a modified example of the reactive power compensation device of FIG. [Figure 9] FIG. 11 is an explanatory diagram showing a device control system according to a second embodiment of the present invention. [Figure 10]FIG. 1 is an explanatory diagram illustrating a conventional device control system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, the embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to each embodiment, and the components can be modified without departing from the gist of the present invention. In addition, various inventions can be formed by appropriately combining multiple components disclosed in each embodiment. For example, some components may be deleted from all the components shown in the embodiments. Furthermore, components of different embodiments may be appropriately combined.

[0023] Embodiment 1 1 is an explanatory diagram showing an equipment control system according to a first embodiment of the present invention. The equipment control system according to the embodiment of the present invention has an equipment 1, a power source 2, and a reactive power compensator 3.

[0024] Equipment 1 is operated at rated power or reduced power. Rated power operation is operation within a range of ±10% of the rated output. Reduced power operation is operation within a range of 10% to less than 90% of the rated output. Rated power output is the output of equipment 1 when a voltage of rated voltage and rated frequency is applied to equipment 1.

[0025] The device 1 may be composed of various devices, but the device 1 in this embodiment is composed of a pump 10. The pump 10 is a type of motor device that includes a motor. The pump 10 may be used in any manner, but in this embodiment, the pump 10 is used to pump up a liquid 41, such as water, stored in a tank 40 and return the liquid 41 to the tank 40. A valve 42 is provided in the piping between the pump 10 and the tank 40.

[0026] The power source 2 supplies AC power to the device 1. Although not limited thereto, the power source 2 may be a commercial power source.

[0027] The reactive power compensator 3 is connected in parallel with the device 1 across the power source 2. The reactive power compensator 3 can adjust the voltage applied to the device 1 from the power source 2 by generating reactive power.

[0028] Next, Fig. 2 is an explanatory diagram showing a method of operating the pump 10 of Fig. 1. In Fig. 2, a curve CL1 including points A and B indicates the characteristics of the pump 10 when the voltage is not adjusted by the reactive power compensator 3. Point A indicates the total head and flow rate of the pump 10 when the valve 42 is fully open. By closing the valve 42, the flow rate of the pump 10 can be adjusted, for example, to point B. A curve CL2 including point C indicates the characteristics of the pump 10 when the voltage is lowered (V1 → V2) by the reactive power compensator 3. Point C indicates a state in which the valve 42 is closed so that the flow rate Q2 on the curve CL2 is the same as that at point B on the curve CL1.

[0029] The work (energy consumption) of the pump 10 is expressed as a constant x total head x flow rate. As can be seen from a comparison between points B and C, even though the same flow rate Q2 can be secured, by lowering the voltage using the reactive power compensator 3, it is possible to reduce the energy consumption in proportion to the shaded area R (=(H1-H2) x Q2). That is, in the equipment control system of this embodiment, energy saving (reduction of energy consumption) can be achieved by the reactive power compensator 3 connected in parallel with the equipment 1 to the power source 2.

[0030] Here, another possible configuration for energy saving is to connect an inverter or the like (INV) in series between the device 1 and the power source 2 (see FIG. 10(a)). If an inverter or the like were connected in series between the device 1 and the power source 2, the current flowing through the device 1 would itself flow through the inverter, causing a large power loss in the inverter, reducing the energy saving effect. Also, if a series-connected inverter or the like breaks down, it would be necessary to stop the system and carry out major repairs, which would be very troublesome.

[0031] In contrast, in the configuration of this embodiment in which the reactive power compensator 3 is connected in parallel with the device 1 to the power source 2, the current flowing through the device 1 does not itself flow through the reactive power compensator 3, and the current flowing through the reactive power compensator 3 is smaller than the current flowing through a series-type inverter or the like. As a result, the power loss in the reactive power compensator 3 is smaller than that in a series-type inverter or the like, and the energy saving effect can be improved. Also, since the reactive power compensator 3 is connected in parallel, even if the reactive power compensator 3 breaks down, the reactive power compensator 3 can be disconnected from the device 1 and the power source 2 without stopping the system, allowing the device 1 to operate, improving the convenience of repairs.

[0032] As described above, the current flowing through the reactive power compensator 3 is relatively small. Therefore, the capacity of the reactive power compensator 3 is small, less than one-third that of a series-type inverter or the like, and the device cost of the reactive power compensator 3 is small compared to a series-type inverter or the like. Furthermore, the device cost of the reactive power compensator 3 is also small compared to the high-efficiency motor (IE3) shown in FIG. 10(b). In other words, the system cost can be reduced by using the reactive power compensator 3 compared to a series-type inverter or the like or a high-efficiency motor (IE3). Furthermore, the reactive power compensator 3 can be easily added to a system in which a standard-efficiency motor (IE1) is already installed.

[0033] In constant speed operation at the rated value of the device 1, a series-connected inverter or the like generates a loss of 2% to 5% of its capacity. In contrast, the loss of the reactive power compensator 3 connected in parallel is small, 1 / 3 or less of the load, since its capacity is the capacity required for voltage adjustment in the first place. Therefore, the loss is also 1 / 3 or less compared to a series-connected inverter or the like. For this reason, the reactive power compensator 3 connected in parallel is particularly useful for the device 1 that is operated at rated power or in output suppression operation. In the device control system of this embodiment, the fluctuation range of the output of the device 1 per second may be 20% or less. In such a system in which the fluctuation range of the output of the device 1 is small, the reactive power compensator 3 connected in parallel is particularly useful.

[0034] Next, Fig. 3 is an explanatory diagram showing a first modified example of the device control system of Fig. 1, and Fig. 4 is an explanatory diagram showing a second modified example of the device control system of Fig. 1. As described above, the device 1 may be composed of various devices. The device 1 may be a blower 11 as shown in Fig. 3, or a heater 12 as shown in Fig. 4. The blower 11 is a type of motor device.

[0035] Next, Fig. 5 is a circuit diagram showing in more detail the reactive power compensator 3 in Fig. 1. The reactive power compensator 3 may be an SVG (Static Var Generator) device 30. The SVG device 30 compensates for reactive power using a self-commutated inverter, and is also called a self-commutated SVC (Static Var Compensator) or STATCOM (STATic synchronous COMpensator).

[0036] The SVG device 30 has an inverter 31, a capacitor 32 connected between the positive and negative bus bars of the inverter 31, and coils 33 connected to each of the AC output terminals (two output terminals) of the inverter 31. The inverter 31 has four transistors T31 to T34 and four diodes D31 to D34 connected in anti-parallel to the corresponding transistors T31 to T34. The four transistors T31 to T34 are connected in pairs, two by two, to serve as the source side and the sink side with respect to the positive bus bar and the negative bus bar of the inverter 31. An inverter output terminal is connected to the connection point between the pair of transistors among the transistors T31 to T34.

[0037] The SVG device 30 controls the switching of the transistors T31 to T34 of the inverter 31 to generate an inverter output voltage V inv The phase of the power supply voltage V s When synchronized with the inverter output voltage V inv supply voltage V s By making it larger than the leading capacitor, it is possible to consume lagging reactive power in the same way as a leading capacitor, and the inverter output voltage V inv supply voltage V sBy making the MOSFET 30 smaller than the lead phase, the SVG device 30 can consume leading reactive power in the same manner as a shunt reactor. That is, the SVG device 30 can continuously control from leading phase to lagging phase.

[0038] In addition, the SVG device 30 does not require a large-capacity capacitor or reactor, so it can be made compact, and since it is connected in parallel with the device 1 to the power source 2, it is easy to install. Furthermore, the SVG device 30 is capable of high-speed voltage adjustment in a dozen or so milliseconds, and the power source voltage V s By generating positive and negative reactive power according to the fluctuation of the power supply voltage V, the voltage fluctuation can be compensated. s The fluctuation of the current and the effective value can be made substantially constant, and various measurements using detectors of the current and voltage input to the device 1 can be performed with high accuracy. o A current detector 51 is connected between the terminals of the SVG terminal to detect the voltage between the terminals (applied voltage V applied to the device 1). ac A voltage detector 52 is connected to detect the voltage Vcc.

[0039] The equipment control system may further include a reactor 60 and a control device 70.

[0040] The reactor 60 is inserted in series between the device 1 and the power source 2. The reactor 60 may have a coil 61 inserted in the electric wire of the power source 2, and a tap changer 62 that switches the tap position of the coil 61. The reactor 60 changes the voltage of the power source 2 (power source voltage V s ) is adjusted in multiple stages and output. The reactor 60 can generate a voltage drop of more than 0% and not more than 30% of the power supply voltage.

[0041] The control device 70 monitors the power consumption of the device 1, and causes the reactive power compensator 3 to change the voltage applied to the device 1 so that the power consumption of the device 1 is reduced. Depending on the device 1, the power consumption may be reduced when the voltage is increased, or reduced when the voltage is decreased. The power consumption of the device 1 is obtained from the value of the current flowing through the device 1 detected by the current detector 53 and the value of the voltage detected by the voltage detector 52.

[0042] The control device 70 is configured as a microprocessor with a CPU 71 as its core, and includes, in addition to the CPU 71, a ROM 72 for storing processing programs such as a motor voltage control process and a power supply voltage coarse adjustment process, which will be described later, a RAM 73 for temporarily storing data, and an input / output port. A detection signal from the current detector 51, a detection signal from the voltage detector 52, a detection signal from a rotation speed sensor 54 for detecting the rotation speed (motor rotation speed N) of the motor included in the device 1, and the like are input to the control device 70 via an input port. A switching control signal 70a and the like to the transistors T31 to T34 of the inverter 31 of the reactive power compensation device 3 are output from the control device 70 via an output port. A tap changing signal 70b to the tap changer 62 may also be output from the control device 70.

[0043] Next, FIG. 6 is a block diagram showing the control block of the SVG device 30. The applied voltage V applied to the device 1 using the SVG device 30 ac Specifically, the control is performed as follows. The SVG device 30 outputs a voltage command V ref and the applied voltage V detected by the voltage detector 52. ac The target output current I of the SVG device 30 is controlled by feedback control (proportional-integral control) based on the deviation from o Then, the SVG device 30 sets the set target output current I o * and the output current I detected by the current detector 51 o The target inverter output voltage V is calculated by feedback control (proportional integral control) based on the deviation from invThen, the SVG device 30 sets the target inverter output voltage V inv * and the applied voltage V detected by the voltage detector 52 ac A PWM (Pulse Width Modulation) signal is generated based on the sum of the input and the output of the inverter 31 to control the switching of each transistor T of the inverter 31. The inverter output voltage V inv As a result, the coil 33 of the SVG device 30 receives the inverter output voltage V inv and the applied voltage V ac The output current I according to the impedance Ls of the coil 33 for the difference o flows. Applied voltage V ac is the output current I o The voltage drop due to the current flowing through the impedance Lgs of the coil 61 is calculated according to the power supply voltage V s The voltage is adjusted to be subtracted from the

[0044] Next, FIG. 7 shows a load voltage V o 13 is an equivalent circuit diagram when controlling the load voltage Vo and a vector diagram showing how the load voltage Vo changes depending on the impedance jωL of the coil 61 and the output current of the SVG device 30.

[0045] A composite current I1 of the SVG current I2 and the load current I3 flows through the impedance jωL of the coil 61. The load voltage Vo is the power supply voltage Es (constant) minus the voltage drop Vx (=jωL×I1) due to the composite current I1 flowing through the impedance jωL. The composite current I1 changes as shown in the figure depending on the sign (leading or lagging) of the SVG current I2, and since the voltage drop Vx in the impedance jωL leads the composite current I1 by 90° in phase, the load voltage Vo can be adjusted by controlling the SVG current I2 output from the SVG device 30. In other words, the applied voltage V of the device 1 is accan be adjusted. The load voltage Vo changes as shown in the figure depending on the magnitude of the impedance jωL. That is, when the SVG device 30 outputs a lagging SVG current I2, when the impedance jωL is doubled, the load voltage Vo becomes smaller than when it is normal, whereas when the SVG device 30 outputs a leading SVG current I2, when the impedance jωL is doubled, the load voltage Vo becomes larger than when it is normal. Therefore, by increasing the inductance L of the coil 61, the voltage adjustment range of the load voltage Vo can be expanded. As a result, by selecting an appropriate coil 61 for the reactor 60, the device 1 can be accurately controlled with an appropriate voltage adjustment range by combining the reactor 60 and the SVG device 30.

[0046] Next, Fig. 8 is a circuit diagram showing a modified example of the reactive power compensation device 3 of Fig. 5. Fig. 5 shows an SVG device 30 corresponding to a power source 2 that outputs single-phase AC power, but as shown in Fig. 8, the SVG device 30 may correspond to a power source 2 that outputs three-phase AC power. In this case, the inverter 31 has six transistors T31-T36 and six diodes D31-D36 connected in anti-parallel to the corresponding transistors T31-T36. The other configuration is the same as that shown in Fig. 5.

[0047] Embodiment 2 Next, Fig. 9 is an explanatory diagram showing a device control system according to a second embodiment of the present invention. As shown in Fig. 9, the device 1 may include a first device 13 and a second device 14 connected in parallel to a power source 2. The first device 13 has a voltage at which power consumption is at a minimum different from that of the second device 14. A reactor 60 is inserted in series between the first device 13 and the power source 2.

[0048] As described above, since the voltage at which the power consumption of the first device 13 is at its lowest is different from that of the second device 14, there is a risk that energy saving will not be achieved even if the same voltage is applied to the first device 13 and the second device 14. By inserting the reactor 60 in series between the first device 13 and the power source 2, energy saving effects can be achieved only for the first device 13, and the impact on the second device 14 can be reduced. The first device 13 is connected to the secondary side of the reactor 60, and the second device 14 is connected to the primary side of the reactor 60. The voltage of the first device 13 can be greatly fluctuated by the reactive power compensation device 3, and energy saving effects can be easily achieved. In contrast, the second device 14 is less susceptible to the voltage fluctuations caused by the reactive power compensation device 3. In the illustrated embodiment, the first device 13 for which energy saving effects are desired is connected to the secondary side of the reactor 60, and the energy saving of the first device 13 is improved in a spot manner by the reactor 60.

[0049] A system impedance 63 may be inserted in series between the power source 2 and the reactor 60. The system impedance 63 is the impedance of existing facilities, wiring, and the like.

[0050] The reactive power compensator 3 is connected in parallel with both the first device 13 and the second device 14 with respect to the power source 2. The reactive power compensator 3 can operate so as to save energy for the first device 13 while minimizing voltage fluctuations applied to the second device 14. The other configurations are the same as those in the first embodiment.

[0051] Although the preferred embodiment of the present invention has been described in detail above with reference to the accompanying drawings, the present invention is not limited to such an example. It is clear that a person having ordinary knowledge in the technical field to which the present invention pertains can conceive of various modified or altered examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally belong to the technical scope of the present invention.

[0052] For example, in the embodiment, the reactive power compensator 3 is described as the SVG device 30, but as the reactive power compensator 3, other devices such as a TSC (Thyristor Switched Capacitors) type device may be used. [Explanation of symbols]

[0053] 1:Equipment 2: Power supply 3: Var compensator 10: Pump 11: Blower 12: Heater 13: 1st device 14:Second device 30:SVG device 31: Inverter 32: Capacitor 33: Coil 60: Reactor 61: Coil 70: Control device

Claims

1. Equipment that is operated at rated power or reduced power output; a power source for supplying AC power to the device; a reactive power compensation device connected in parallel with the device to the power source; An equipment control system comprising:

2. The reactive power compensation device is a static var generator (SVG). The device control system according to claim 1 .

3. The SVG device includes an inverter, a capacitor connected between positive and negative busbars of the inverter, and a coil connected to each of the AC output terminals of the inverter. The device control system according to claim 2 .

4. The rated operation is an operation within a range of ±10% of the rated output. The device control system according to claim 1 .

5. The output suppression operation is an operation within a range of 10% to less than 90% of the rated output. The device control system according to claim 1 .

6. The fluctuation range of the output of the device per second is 20% or less. The device control system according to any one of claims 1 to 5.

7. A control device is further provided that monitors the power consumption of the device and changes the voltage applied to the device to the reactive power compensation device so that the power consumption of the device is reduced. The device control system according to any one of claims 1 to 5.

8. The device further includes a reactor inserted in series between the device and the power source. The device control system according to any one of claims 1 to 5.

9. The reactor generates a voltage drop of more than 0% and not more than 30% of the power supply voltage. The equipment control system according to claim 8.

10. the devices include a first device and a second device connected in parallel to the power source; The first device has a voltage at which power consumption is at a minimum different from that of the second device, The reactor is inserted in series between the first device and the power source. The equipment control system according to claim 8.

11. The device is a motor device or a heater. The device control system according to any one of claims 1 to 5.

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