JP4666647B2 - Power recovery system - Google Patents

Description

  The present invention relates to a power recovery system that recovers energy from an energy source such as high-pressure air or steam as a driving force of an electric motor.

  Conventionally, as disclosed in Patent Document 1 below, a system is known that generates power by driving a turbine using an energy source such as steam. In the system of Patent Document 1, a screw type expander is connected to a generator, and when the steam is introduced into the screw type expander, the expander is driven, and thereby the generator generates power. ing.

On the other hand, Patent Documents 2 and 3 below disclose a system in which a power generation unit is system-connected to a commercial system via a system interconnection inverter. For example, in the system of Patent Document 2, a plurality of power generation units such as a wind power generation unit and a solar power generation unit and a power storage unit are connected to a DC bus, and a system for connecting a power generation unit whose output power changes drastically is provided. ing.
JP 61-291706 A JP 2003-339118 A Japanese Patent Laid-Open No. 2005-39935

  By the way, since the system disclosed in each of the above patent documents is a system that generates power, it is necessary to have a system protection function or the like in accordance with technical guidelines for system interconnection. That is, in the system of Patent Document 1, for example, when power is supplied to a specific machine in the factory, there is a possibility of interfering with the power supply in the factory, and since it is also connected to an external power supply line, the system protection function, etc. Is required. In addition, it is necessary to have an interconnection protection system individually by conducting interconnection discussions with electric power companies according to the scale of installed equipment. Even if the power handled here does not exceed the amount consumed in the entire office, it is necessary to apply for interconnection in the form of “no reverse tide”. On the other hand, in the systems of Patent Documents 2 and 3, since it is necessary to connect to the grid, there is a possibility that electric power may be supplied to the outside (with reverse power flow), and when there is no power (with no reverse power flow). It is necessary to provide a system protection function. This is because even if there is no problem on the external system, if there is a problem on the distributed power supply side, it may affect the power equipment in the facility. Therefore, the conventional system is effective in using the electric power generated by using the energy of the energy source, but the generated electric power may affect other electric power devices, and the system protection function Etc. are bothersome.

  Therefore, the present invention has been made in view of such a point, and the object of the present invention is to be able to effectively use the power generated using the energy of the energy source without providing a system protection function or the like. Is to make it.

In order to achieve the above object, the present invention provides a power recovery system that recovers energy from an energy source as power, a main power system that is connected to a system power source, and an electric motor that is connected to the main power system. And an auxiliary power supply system configured independently of the main power supply system, capable of supplying electric power generated using energy of an energy source and applying driving force to the electric motor according to the electric power, And a controller that performs control to suppress power supply by the auxiliary power supply system so that a reverse power flow due to the electric motor does not occur.

In the present invention, the electric motor is driven by the electric power supplied from the main power supply system, while the driving force of the electric motor is supplemented by the electric power supplied through the auxiliary power supply system. Therefore, the energy of the energy source is recovered as the driving force of the electric motor. be able to. In addition, since control for suppressing power supply by the auxiliary power supply system is performed so as to avoid reverse tide caused by the electric motor, it is not necessary to provide a system protection function or the like. In addition, when control is performed in a range where reverse tide does not occur, there is a case of shifting to the power generation region, but even in this case, if the power generation amount is sufficiently small compared to the power receiving capacity in the entire facility, Since reverse tide does not occur, it is not necessary to immediately reduce the amount of power supplied by the auxiliary power system.

  Here, the controller can control the power supply by the auxiliary power supply system so that the mechanical angle of the electric motor does not become larger than the electrical angle.

  In this aspect, since the power supply by the auxiliary power supply system is controlled so that the mechanical angle of the motor does not precede the electrical angle, it is possible to reliably avoid the motor from generating power.

  The auxiliary motor may be configured separately from the electric motor, and may include an auxiliary electric motor having a rotating shaft connected to the rotating shaft of the electric motor, and the auxiliary electric motor may be connected to the auxiliary power supply system.

  Since this aspect is a configuration in which the electric motor and the auxiliary electric motor are connected, it can be used for assisting the driving force of the existing electric motor. That is, by connecting the rotating shaft of the auxiliary motor to the rotating shaft of the existing motor, the energy of the energy source can be recovered as the driving force of the motor.

  In this aspect, it is preferable that the controller controls power supply by the auxiliary power supply system so that the rotational speed of the auxiliary motor matches the rotational speed of the motor.

  In this aspect, since the rotation speed of the electric motor and the rotation speed of the auxiliary motor are controlled to coincide with each other, the electric motor is not increased by the driving force of the auxiliary electric motor. As a result, it is possible to reliably avoid power generation by the electric motor.

  On the other hand, the electric motor may be equipped with a winding connected to the main power supply system and a winding connected to the auxiliary power supply system.

  In this aspect, the electric power of the main power supply system is supplied to the electric motor and the electric power of the auxiliary power supply system is supplied. For this reason, it is not necessary to provide an electric motor separately from this electric motor, and the power recovery system as a whole can have a compact design.

  In this aspect, it is preferable that the controller controls power supply by the auxiliary power supply system so that current phases in both windings coincide with each other.

  In this aspect, since the electric power supplied from each power supply system can be added effectively, the drive efficiency of the electric motor can be improved.

  Further, when the electric motor is provided with a rotation angle detection means for detecting the rotation angle of the rotor, the controller is configured so that the current phases in both windings coincide with each other based on the detected rotation angle. It is preferable to control the power supply by the auxiliary power system.

  In this aspect, since the current phase in both windings is matched by using the detected rotation angle, it is not necessary to detect the current phase and voltage phase of each winding. For this reason, for example, in a motor having a rotor angle detection sensor such as a permanent magnet synchronous motor, this detection sensor can be used. In this case, it is not necessary to newly add a current detection sensor or the like.

  The winding of the main power supply system and the winding of the auxiliary power supply system may be arranged in different slots.

  In this aspect, the space in the electric motor can be used effectively.

  The auxiliary power supply system may be configured to be connectable to a plurality of energy sources, and may be provided with a converter that individually converts power obtained from each energy source into DC power.

  In this aspect, since the electric power based on each energy source is individually converted, it is possible to easily ensure a constant DC voltage. Thereby, the diversity of a power supply can be absorbed.

  As described above, according to the present invention, electric power generated using a power source can be effectively used without providing a system protection function or the like.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 schematically shows an embodiment of a power recovery system according to the present invention. The power recovery system 10 of the first embodiment is connected to a main power system 13, a main motor 15 as an example of an electric motor connected to the main power system 13, an auxiliary power system 30, and the auxiliary power system 30. An auxiliary motor 33 as an example of the auxiliary motor and a controller 60 are provided.

  The main power supply system 13 is connected to the system power supply 17, and three-phase AC power is supplied from the system power supply 17. The main power supply system 13 has a power converter (converter inverter) 19, which converts the three-phase AC power supplied from the system power supply 17 into a predetermined frequency, and has a predetermined frequency. Convert to the voltage of

  The main motor 15 is constituted by a synchronous motor. The main motor 15 is provided with a rotor angle detection sensor 21 for detecting the rotation angle of the rotor. The rotor angle detection sensor 21 is composed of, for example, a Hall element. In many cases, the permanent magnet synchronous motor is provided with a rotor position sensor in order to prevent loss of synchronization. If the main motor 15 is a permanent magnet synchronous motor, the rotor position sensor may be applied as the rotor angle detection sensor 21.

  The rotating shaft 15 a of the main motor 15 and the rotating shaft 33 a of the auxiliary motor 33 are connected to each other through the coupling 20. The rotating shaft 15 a of the main motor 15 is connected to a load, and a driving force is applied to the load 23 by driving the main motor 15.

  The auxiliary power supply system 30 includes a generator 35 and is configured to be able to supply electric power generated by the generator 35 to the auxiliary motor 33. The rotating shaft of the generator 35 is coupled to a driving shaft of a screw expander 37 as an example of an energy source that is driven by energy such as high-pressure air and steam, and generates electric power according to the driving force of the screw expander 37. To do. The energy source is not limited to one driven by energy such as high-pressure gas or steam, and may be one driven by energy such as sunlight or wind power.

  The auxiliary power supply system 30 includes a converter 39 that converts the three-phase alternating current generated by the generator 35 into a direct current having a predetermined voltage, and an inverter 41 that converts the direct current obtained by the converter 39 into a three-phase alternating current having a predetermined frequency. And have. Three-phase (u-phase, v-phase, w-phase) AC power generated by the inverter 41 is supplied to the auxiliary motor 33.

  The auxiliary motor 33 is constituted by a synchronous motor, for example, a permanent magnet synchronous motor in which the rotor 43 is provided with a permanent magnet 43a. The stator 45 of the auxiliary motor 33 is provided with the u-phase, v-phase, and w-phase windings 47 of the auxiliary power supply system 30, and the auxiliary motor 33 outputs the three-phase AC power output from the inverter 41. It comes to be driven by.

  The controller 60 includes an electrical angle deriving unit 61, a mechanical angle deriving unit 62, a phase difference deriving unit 63 for deriving a phase difference in the main motor 15, and a phase difference derived by the phase difference deriving unit 63. And a power control unit 64 that controls the inverter 41. The electrical angle deriving unit 61 derives the electrical angle that is the phase of each phase from the AC current of each phase supplied to the main motor 15. The mechanical angle deriving unit 62 derives a mechanical angle that is a phase (rotational angle) of the rotor 43 of the main motor 15 based on the signal output from the rotor angle detection sensor 21. The phase difference deriving unit 63 uses the electrical angle derived by the electrical angle deriving unit 61 and the mechanical angle derived by the mechanical angle deriving unit 62 to derive a phase difference between the electrical angle and the mechanical angle.

  The power control unit 64 controls the inverter 41 of the auxiliary power supply system 30 so that the phase difference obtained by subtracting the mechanical angle from the electrical angle does not become negative. In other words, the main motor 15 and the auxiliary motor 33 are connected to each other, and the auxiliary motor 33 assists the main motor 15. And since the electric power supplied to this auxiliary motor 33 is adjusted with the inverter 41, the driving force which assists the main motor 15 can be adjusted by controlling the inverter 41 with the signal from the electric power control part 64. . On the other hand, when the load 23 is applied to the main motor 15, the mechanical angle is delayed from the electrical angle. However, when the driving force of the auxiliary motor 33 is excessive, the mechanical angle of the main motor 15 precedes the electrical angle. Therefore, the main motor 15 generates power. For this reason, the power control unit 64 is configured to control the inverter 41 of the auxiliary power supply system 30 so that the mechanical angle of the main motor 15 does not precede the electrical angle.

  Here, the control operation of the power recovery system 10 according to the first embodiment will be described. By turning on the main power supply system 13 and driving the main motor 15, a rotational driving force is applied to the load 23. At this time, the driving force of the main motor 15 can be shared by driving the auxiliary motor 33. Specifically, when steam or the like is introduced into the screw expander 37 and the screw expander 37 is driven, the generator 35 generates power. The AC power generated by the generator 35 is converted to DC power by the converter 39 and then converted to AC power by the inverter 41. The auxiliary motor 33 assists the driving force of the main motor 15 by rotating the rotor 43 with the electric power output from the inverter 41.

  At this time, the inverter 41 adjusts the voltage and frequency of the output power according to the signal from the controller 60. In other words, when the electrical angle and mechanical angle of the main motor 15 are derived by the controller 60 and the mechanical angle becomes larger than the electrical angle, the power of the main motor 15 is controlled by suppressing the power output from the inverter 41. Control the angle so that it does not exceed the electrical angle. As a result, it is possible to assist the driving force of the main motor 15 by the auxiliary motor 33 while avoiding power generation in the main motor 15.

  As described above, according to the first embodiment, the main motor 15 is driven by the electric power supplied from the main power supply system 13, while the driving force of the main motor 15 is supplemented by the electric power supplied through the auxiliary power supply system 30. Therefore, the power of the energy source can be recovered as the driving force of the main motor 15. Therefore, power supplied by the main power supply system 13 can be saved. In addition, since the power supply by the auxiliary power supply system 30 is controlled so that the reverse power flow by the main motor 15 is avoided, the power recovery system 10 according to the first embodiment does not need to have a system protection function or the like. Therefore, the electric power generated using the energy of the energy source can be effectively used without providing a system protection function or the like.

  Moreover, in the first embodiment, since the power supply by the auxiliary power supply system 30 is controlled so that the mechanical angle of the main motor 15 does not become larger than the electrical angle, it is possible to reliably avoid the main motor 15 from generating power. it can.

  In the first embodiment, the auxiliary motor 33 is provided separately from the main motor 15, and the rotating shaft 33 a of the auxiliary motor 33 is connected to the rotating shaft 15 a of the main motor 15. Can be used for assistance. In other words, the energy of the energy source can be recovered by connecting the rotation shaft 33a of the auxiliary motor 33 to the existing rotation shaft 15a of the main motor 15.

  Further, by configuring the main motor 15 to be assisted by the auxiliary motor 33, it is possible to reduce the power load when the main motor 15 is started. For example, in the past, in the case of a load that requires a large torque at startup, the startup current may be several times the rated value, and startup may not be possible. There was a possibility that the voltage of the power source of the equipment would be lowered, and various electric equipments might be damaged. However, in the first embodiment, the driving power of the main motor 15 can be reduced by driving the auxiliary motor 33 in advance by supplying power from the auxiliary power supply system 30. Therefore, even when the load 23 that requires a large torque is connected, the main motor 15 can be started smoothly. Moreover, it is not necessary to provide a reduced voltage starting device.

  In the first embodiment, the electric angle and the mechanical angle are detected and the inverter 41 is controlled so that the phase difference does not become negative. However, the present invention is not limited to this. For example, the inverter 41 may be controlled so that the synchronous rotational speed of the auxiliary motor 33 matches the synchronous rotational speed of the main motor 15. In this way, since the rotation speed of the main motor 15 and the rotation speed of the auxiliary motor 33 are controlled to coincide with each other, it is possible to reliably avoid the main motor 15 from generating power. In this case, the controller 60 includes a main motor electrical angle deriving unit, an auxiliary motor electrical angle deriving unit, and a power control unit, and the power control unit includes phases of current and voltage supplied to the main motor 15. Then, the inverter 41 is controlled so that the phases of the current and voltage phases supplied to the auxiliary motor 33 coincide with each other. It is also possible to set the rotational speed of the auxiliary motor 33 to be higher than the rotational speed of the main motor 15 within a range where no reverse tide occurs.

  In the first embodiment, the main motor 15 and the auxiliary motor 33 are configured by a synchronous motor, but instead, the main motor 15 and the auxiliary motor 33 may be configured by an induction motor. In this case, in order to prevent reverse tide by the main motor 15, control may be performed so that the rotation speeds of the main motor 15 and the auxiliary motor 33 coincide. That is, the rotational speed derived from the frequency of the alternating current supplied to the main motor 15 may be indicated as the rotational speed of the auxiliary motor 33.

  In the first embodiment, the auxiliary power supply system 30 is provided with one energy source. However, the present invention is not limited to this. That is, the auxiliary power supply system 30 may be provided with a plurality of generators 35 and energy generators such as screw expanders may be connected to the generators 35.

(Embodiment 2)
FIG. 2 schematically shows the overall configuration of a power recovery system 10 according to the second embodiment of the present invention. In the first embodiment, two motors are connected. In the second embodiment, the main power supply system 13 and the auxiliary power supply system 30 are connected to one electric motor. Although specifically described below, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The power recovery system 10 according to the second embodiment includes an electric motor 71, and the electric motor 71 is provided with two windings. That is, the stator 73 of the electric motor 71 is provided with a winding (main winding) 74 connected to the main power supply system 13 and a winding (auxiliary winding) 76 connected to the auxiliary power supply system 30. It has been. The main winding 74 and the auxiliary winding 76 are accommodated in separate slots in the casing of the electric motor 71.

  The main power supply system 13 is connected to the system power supply 17, and three-phase AC power is supplied from the system power supply 17. On the other hand, the auxiliary power supply system 30 is provided with a plurality of generators 35, and each generator 35 is connected to an energy source, and the generator 35 generates power using the energy of the energy source. . Each energy source may be the same type of drive, or may be a different type of drive. Although the 1st energy source is comprised by the screw expander 37, it is not restricted to this. Other energy sources are not shown, but may be screw expanders, drivers used in wind power generators, and the like.

  A converter 39 is connected to each generator 35, and each converter 39 converts AC power from the generator 35 into DC power of a predetermined voltage. Each of these converters 39 is connected in parallel to the pre-stage inverter 78. For this reason, the electric power of a constant voltage is easily supplied to the pre-stage inverter 78 regardless of the power generation state in each generator 35. Then, the electric power converted into the three-phase alternating current by the front stage inverter 78 is supplied to the auxiliary winding 76 through the inverter 82 and is used by the electric motor 71.

  The electric motor 71 is constituted by a synchronous motor, and is, for example, a permanent magnet synchronous motor in which a permanent magnet (not shown) is provided on the rotor 79. The electric motor 71 is provided with a rotor angle detection sensor 84 for detecting the rotation angle of the rotor 79. The rotor angle detection sensor 84 is composed of, for example, a Hall element.

  The power control unit 64 of the controller 60 is provided in the inverter (main power supply side inverter) 80 provided in the main power supply system 13 and the auxiliary power supply system 30 based on the signal output from the rotor angle detection sensor 84. The inverter (auxiliary power supply side inverter) 82 is controlled. The main power supply side inverter 80 and the auxiliary power supply side inverter 82 output currents whose phases match each other based on the signal from the power control unit 64. Since the phases of the currents supplied to the main winding 74 and the auxiliary winding 76 coincide with each other, the power supplied from the power supply systems 13 and 30 can be effectively added, thereby improving the driving efficiency. it can. In addition, by appropriately setting the impedances of the main winding 74 and the auxiliary winding 76, it is possible to adjust the sharing ratio between the driving force by the main power supply system and the driving force by the auxiliary power supply system. Therefore, the system efficiency can be optimized by adjusting the sharing ratio according to the capacity of the energy source.

  In the second embodiment, since the electric power of the main power supply system 13 is supplied to the electric motor 71 and the electric power of the auxiliary power supply system 30 is supplied, it is not necessary to provide an electric motor separately from the electric motor 71, and the entire power recovery system 10 is provided. As a compact design.

  In the second embodiment, since the current phase in both windings 47 is matched by using the rotation angle of the rotor detected by the rotor angle detection sensor 21, the current phase and voltage phase of each winding 47 are matched. Need not be detected. In addition, in a motor having a rotor angle detection sensor 21 such as a permanent magnet synchronous motor, the rotor angle detection sensor 21 can be used, so that it is not necessary to newly add a current detection sensor or the like.

  In the second embodiment, since the main winding 74 and the auxiliary winding 76 are arranged in different slots, the space in the electric motor 71 can be used effectively. The main winding 74 and the auxiliary winding 76 may be stored in the same slot.

  In the second embodiment, the auxiliary power supply system 30 is connected to a plurality of energy sources, and the converter 39 for individually converting the AC power of each generator 35 to DC power is provided. The power based on the energy source is converted individually. For this reason, it is easy to ensure a constant DC voltage, and the diversity of power sources can be absorbed.

  As shown in FIGS. 3 and 4, one energy source may be connected to the auxiliary power supply system 30. 3 and 4, the main winding 74 and the auxiliary winding 76 are disposed in the same slot, but may be disposed in different slots.

It is a figure showing roughly the whole power recovery system composition concerning a 1st embodiment of the present invention. It is a figure which shows roughly the whole structure of the power recovery system which concerns on 2nd Embodiment of this invention. It is a figure which shows roughly the whole system of the modification of 2nd Embodiment. It is a figure which shows the electric motor provided in the system of FIG.

Explanation of symbols

13 Main power supply system 15 Main motor (an example of an electric motor)
15a Rotating shaft 21 Rotor angle detection sensor (an example of rotation angle detection means)
30 Auxiliary power supply system 33 Auxiliary motor (an example of an auxiliary motor)
33a Rotating shaft 37 Screw expander (an example of energy source)
39 Converter 60 Controller 61 Electrical Angle Deriving Unit 62 Mechanical Angle Deriving Unit 63 Phase Difference Deriving Unit 64 Power Control Unit 71 Electric Motor 74 Main Winding 76 Supplementary Winding

Claims (9)

A power recovery system that recovers energy from an energy source as power,
A main power system connected to the system power supply,
An electric motor connected to the main power system;
An auxiliary power supply system configured independently of the main power supply system, capable of supplying electric power generated using energy of an energy source and applying driving force to the electric motor according to the electric power;
A power recovery system comprising: a controller that performs control to suppress power supply by the auxiliary power supply system so that no reverse tide is generated by the electric motor.   The power recovery system according to claim 1, wherein the controller controls power supply by the auxiliary power supply system so that a mechanical angle of the electric motor does not become larger than an electrical angle.   2. The power recovery system according to claim 1, further comprising an auxiliary electric motor configured separately from the electric motor and having a rotating shaft connected to the rotating shaft of the electric motor, wherein the auxiliary electric motor is connected to the auxiliary power supply system.   The power recovery system according to claim 3, wherein the controller controls power supply by the auxiliary power supply system so that a rotation speed of the auxiliary motor matches a rotation speed of the electric motor.   2. The power recovery system according to claim 1, wherein a winding connected to the main power supply system is attached to the electric motor, and a winding connected to the auxiliary power supply system is attached to the electric motor.   The power recovery system according to claim 5, wherein the controller controls power supply by the auxiliary power supply system so that current phases in both windings coincide with each other. The electric motor includes rotation angle detection means for detecting the rotation angle of the rotor,
The power recovery system according to claim 6, wherein the controller controls power supply by the auxiliary power supply system so that current phases in both windings coincide with each other based on the detected rotation angle.   The power recovery system according to claim 5, wherein the winding of the main power supply system and the winding of the auxiliary power supply system are arranged in different slots. 9. The auxiliary power system is configured to be connectable to a plurality of energy sources, and is provided with a converter that individually converts electric power obtained from each energy source into DC power. The power recovery system described in 1.

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