JP2011012848A - System interconnection system using gas heat pump-type air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve high energy consumption efficiency by efficiently returning surplus electric power in driving of a gas engine to a system while properly controlling air-conditioning.SOLUTION: In this system interconnection system S including a generator 30, a gas heat pump-type air conditioner 1 having an AC/DC converting section 34, and a convertor 40 for converting DC electric power converted by the AC/DC converting section into AC electric power of the system to which an air conditioner 1 is connected, and returning the same to the system, the convertor 40 executes the control to follow up a point of the maximum output power, and controls the electric current flowing to the convertor 40 from the AC/DC converting section 34 to follow up a point of the maximum output voltage of the convertor 40 on the basis of an operating condition of the air conditioner 1.

Description

  The present invention uses a compressor and a generator constituting a refrigeration cycle, a gas heat pump type air conditioner including a gas engine that drives the compressor and the generator, and uses the power generated by the generator as a system. The present invention relates to a grid interconnection system that can be returned.

  Conventionally, in a gas heat pump (GHP) type air conditioner, a compressor constituting a refrigeration cycle is driven by a gas engine to perform an air conditioning operation, and a generator is driven by the gas engine to store generated power. Are charged or supplied in parallel to auxiliary devices such as each blower to perform these operations. By using a step-up / step-down device or an inverter, the auxiliary power is converted into the same power as that of a commercial power source (for example, AC 200 V 50 Hz or 60 Hz) and supplied (for example, see Patent Document 1).

  On the other hand, recently, a photovoltaic power generation system has been developed in which a distributed power source using solar cells is connected to a commercial power system (distribution system). In this solar power generation system, DC power generated by a solar cell is boosted by a booster circuit of a grid-connected inverter device (so-called power conditioner), and the boosted DC power is converted to AC power by an inverter circuit. The converted AC power is controlled by the control means and supplied to the commercial power system.

  In this case, the output voltage-output current characteristic of the solar cell is represented by a curve as shown in FIG. The output power gradually increases when the output voltage of the solar cell is from 0 V to a predetermined voltage, and when it exceeds this predetermined voltage, the output power gradually decreases. The output power at the predetermined voltage is the maximum power of the solar cell, and this portion is called the maximum power point Pm. As a control for taking out the maximum power from the solar cell having such characteristics, the maximum power tracking control (hereinafter referred to as “Maximum Power Point Tracking” (hereinafter referred to as “Maximum Power Point Tracking”)) is performed. "MPPT control" is known (see Patent Document 2).

  In this MPPT control, the voltage command value, which is the control target value of the operating voltage of the solar cell, is slightly changed at regular time intervals, and the output power of the solar cell at this time is measured and compared with the previous measured value. The operating point of the solar cell is brought close to the maximum power point (optimal operating point) by the procedure of changing the voltage command value in the direction in which the output power always increases.

JP 2008-107000 A JP-A-11-282553

  Here, using the power conditioner for solar power generation, the power generated by the generator of the GHP type air conditioner is converted into a commercial power source. It is conceivable to supply lighting and other loads within the same facility. The power conditioner for photovoltaic power generation that executes the MPPT control as described above can efficiently output the generated power from the solar cell that changes depending on the sunshine condition. Therefore, when the power output from the generator of the GHP air conditioner is controlled according to the demand of the power conditioner, a large amount of current is taken into the power conditioner regardless of the air conditioning load in the air conditioner.

  As a result, the load on the generator increases, and the driving force for the gas engine to drive the compressor is insufficient, resulting in poor air conditioning. In addition, the gas engine is overloaded, and in the worst case, the engine is stopped.

  The present invention has been made in order to solve the conventional technical problem, and achieves high energy consumption by efficiently returning the surplus power generated by driving the gas engine to the system while realizing appropriate air conditioning control. Realize efficiency.

  In order to solve the above problems, the grid interconnection system of the present invention is generated by a compressor, a generator constituting the refrigeration cycle, a gas engine driving the compressor and the generator, and the generator. A gas heat pump type air conditioner having a first converter that converts AC power into DC power and a control means, and a system in which the DC power converted by the first converter is connected to the air conditioner And a second converter that converts the power into the specified frequency AC power and returns it to the system, and the second converter performs control to follow the point at which the output power is maximum, The control means controls the current flowing from the first converter to the second converter based on the operating state of the air conditioner so as to follow the point where the output power of the second converter becomes maximum. It is characterized by.

  According to the present invention, a compressor and a generator that constitute a refrigeration cycle, a gas engine that drives the compressor and the generator, and a first converter that converts AC power generated by the generator into DC power. A gas heat pump type air conditioner equipped with a converter and a control means, and the direct current power converted by the first converter is converted into the specified frequency alternating current power of the system to which the air conditioner is connected to the system. In the grid interconnection system including the second converter to return to the second converter, the second converter performs control to follow the point where the output power is maximum, and the control means is the operating state of the air conditioner Based on the above, the current flowing from the first converter to the second converter is controlled so as to follow the point where the output power of the second converter becomes maximum, so that a large amount of current is supplied to the second converter. And the load on the generator increases. There it is possible to avoid a disadvantage that the driving force for driving the compressor is insufficient.

  As a result, the generator can be driven by the surplus power of the gas engine that drives the compressor, the air conditioning control by the compressor is not hindered, and the surplus power generated by driving the gas engine is efficiently used. Thus, it is possible to return to the grid and realize high energy consumption efficiency.

  In particular, the second converter performs control to follow the point where the output power becomes maximum, that is, MPPT control, and the control means is based on the operating state of the air conditioner. Thus, the current flowing through the second converter can be controlled to follow the point at which the output power of the second converter is maximum.

  As a result, the air conditioning control by the compressor can be executed smoothly, and the current flowing from the first converter to the second converter can be efficiently executed in the second converter by the MPPT control. Since the electric current is controlled so as to become electric current, surplus electric power generated by driving the gas engine can be more efficiently supplied to the system, and efficient operation can be realized.

It is a schematic block diagram of the grid connection system using a gas heat pump type air conditioner. It is a schematic block diagram of a gas heat pump type air conditioner. It is a flowchart of the current control which flows into a power conditioner from an AC / DC conversion part. It is a figure which shows the output voltage-output current characteristic of the solar cell in the power conditioner for solar power generation.

  Hereinafter, an embodiment of a grid interconnection system S using the gas heat pump type air conditioner 1 of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a grid interconnection system S using a gas heat pump type air conditioner 1, and FIG. 2 is a schematic configuration diagram of the gas heat pump type air conditioner 1. The grid interconnection system S in the present embodiment includes a gas heat pump type air conditioner 1 and a power conditioner 40 for photovoltaic power generation.

  The gas heat pump type air conditioner 1 is composed of an outdoor unit 2 installed outdoors and, for example, a wall-mounted indoor unit 3 disposed indoors and provided with an indoor heat exchanger (use side heat exchanger). Both are connected by a refrigerant pipe (liquid pipe 4A and gas pipe 4B) through a service valve (not shown). In the figure, the outdoor unit 2 is indicated by a two-dot chain line, and the indoor unit 3 is indicated by a one-dot chain line.

  The outdoor unit 2 includes a compressor 12 that constitutes a refrigeration cycle, a generator 30, a gas engine 10 that drives the compressor 12 and the generator 30, and an air conditioner electrical unit 35 that includes a control device (control means) C. It has.

  The refrigeration cycle includes a compressor 12, an accumulator 13, a four-way valve 23, an outdoor heat exchanger (heat source side heat exchanger) 17, an expansion valve 24 as decompression means, It is comprised by the indoor side heat exchanger (use side heat exchanger) 15 arrange | positioned at the unit 3. FIG. An accumulator 13 is connected to the suction side of the compressor 12, and a four-way valve 23 is connected to the discharge side. The outdoor heat exchanger 17 and the expansion valve 24 are sequentially connected to the side to which the four-way valve 23 is connected, and the indoor heat exchanger 15 is connected via a liquid pipe 4A provided with a service valve. A gas pipe 4B provided with a service valve is connected to the refrigerant outlet side of the indoor heat exchanger 15, and the gas pipe 4B is connected to the four-way valve 23. This constitutes an annular refrigeration cycle. The compressor 12, the expansion valve 24, the four-way valve 23, and the like are connected to and controlled by the control device C of the air conditioning electrical equipment section 35.

  In the vicinity of the outdoor heat exchanger 17 disposed in the outdoor unit 2, an outdoor blower 18 that blows air to the outdoor heat exchanger 17 is disposed. Further, an indoor fan 16 for blowing air to the indoor heat exchanger 15 is disposed in the vicinity of the indoor heat exchanger 15 disposed in the indoor unit 3. As a general rule, these blowers 16 and 18 are supplied with electric power through an air conditioning electrical unit 35 fed by a power conditioner 40 as will be described in detail later, and are controlled by a control device C of the air conditioning electrical unit 35. . Here, a commercial power system (AC line) 44 for supplying power from the commercial power supply 41 is connected to the air conditioning electrical component 35, and air conditioning is performed when the generator 30 is not generating power. Electric power is supplied from the commercial power supply 41 to the electrical equipment unit 35.

  Therefore, the gas heat pump type air conditioner 1 is set to the cooling operation or the heating operation by switching the four-way valve 23 by the control device C of the air conditioning electrical equipment unit 35. That is, when the four-way valve 23 is switched to the cooling operation side, the refrigerant circulating in the refrigeration cycle is discharged from the compressor 12 as indicated by the broken line arrow, and then flows into the outdoor heat exchanger 17 acting as a condenser. After the heat is dissipated, the pressure is reduced by the expansion valve 24 and flows into the indoor heat exchanger 15 acting as an evaporator, evaporates and exhibits a cooling action, and then returns to the compressor 12. Thereby, the room to be conditioned is cooled by the indoor heat exchanger 15. On the other hand, when the four-way valve 23 is switched to the heating operation side, the refrigerant sealed in the refrigerant circuit is discharged from the compressor 12 as indicated by a solid line arrow, and then enters the indoor heat exchanger 15 acting as a condenser. After flowing in and dissipating heat, the pressure is reduced by the expansion valve 24, flows into the outdoor heat exchanger 17 acting as an evaporator, evaporates, and then returns to the compressor 12. Thereby, the room is heated by the indoor heat exchanger 15.

  The compressor 12 is detachably connected to the gas engine 10 via an electromagnetic clutch (transmission means) 14 and compresses the refrigerant by the driving force of the gas engine 10. The generator 30 has a function of generating power by the driving force of the gas engine 10, and even when the clutch 14 is disconnected, the generator 30 supplies sufficient power as a power generation system by driving the gas engine 10. It is possible.

  On the other hand, the gas engine 10 provided in the outdoor unit 2 is operated by the fuel gas supplied from the fuel supply system. That is, a fuel supply pipe 25 is connected to the gas engine 10, and a fuel cutoff valve 26, a zero governor 27, and a fuel adjustment valve 28 that are controlled to open and close by the control device C of the air conditioning electrical equipment 35 are sequentially connected to the fuel supply pipe 25. It is connected.

  The fuel shut-off valve 26 is selectively closed or fully opened to selectively control the shutoff and flow of the fuel gas. The zero governor 27 adjusts the fuel supply to the gas engine 10 at a constant pressure on the fuel adjustment valve 28 side even if the fuel cutoff valve 26 side causes a pressure fluctuation in the fuel supply pipe 25 due to the open / close control. The fuel adjustment valve 28 optimally adjusts the air-fuel ratio of the mixed gas generated by mixing the fuel gas and air.

  The gas engine 10 is provided in the outdoor unit 2 and burns the gas supplied from the fuel supply system to generate a driving force, and the compressor 12 is driven by the driving force. Waste heat generated by the combustion of gas is cooled by circulating engine cooling water. That is, the cooling water path 5 of the gas engine 10 includes a cooling water pump 21 that circulates the engine cooling water and a radiator 19 that radiates the engine cooling water. The radiator 19 is provided with a radiator blower 20. The radiator blower 20 blows air to the radiator 19, thereby accelerating the heat radiation of the cooling water. The cooling water pump 21 and the radiator blower 20 are controlled by the control device C of the air conditioning electrical equipment section 35.

  As a result, the cooling water pump 21 is always operated while the gas engine 10 is being driven, so that the engine cooling water circulates through the cooling water path 5 through the gas engine 10, the cooling water pump 21, and the radiator 19 in order. As a result, the gas engine 10 is cooled.

  Here, the power generation system by the generator 30 will be described. An AC / DC converter 34 as a first converter is connected to the generator 30 via an AC line 42. The AC / DC converter 34 is constituted by a boost converter that rectifies and converts the three-phase AC power generated by the generator 30 into DC power and outputs a constant output, for example, 300V. The AC / DC converter 34 is connected to a power conditioner 40 for photovoltaic power generation used as a second converter via a DC line 43.

  The power conditioner 40 for photovoltaic power generation includes an inverter circuit 40A that converts boosted DC power into AC power, and the power conditioner 40 is connected to the commercial power system 44 via an AC line 45. The Since the power conditioner 40 in the present embodiment is a power conditioner for solar power generation that is widely used, the operating point of the solar cell usually always tracks the maximum power point so as to extract the maximum power from the solar cell. MPPT control which is maximum power tracking control to be changed to is executed. In this case, MPPT control is executed so as to extract the maximum power from the AC / DC converter 34 connected via the DC line 43.

  Hereinafter, the operation of the grid interconnection system S during the air conditioning control will be described with reference to the flowchart of FIG. When the operation start instruction is input from the remote controller connected to the indoor unit 3 through the communication line, the control device C of the air conditioning electrical equipment unit 35 in this embodiment has an intake air temperature of the indoor heat exchanger 15. The air conditioning load is acquired in real time based on the input from the temperature sensor 37 that detects the above. And the rotation speed of the gas engine 10 is specified so that it may become the air conditioning priority operation capability corresponding to the said air-conditioning load, and the rotation speed of the gas engine 10 is controlled so that it may become this rotation speed.

  Thus, in the control device C, the compressor 12 and the generator 30 connected to the gas engine 10 are driven by the clutch 14. The control device C controls the rotational speed of the gas engine 10 so as to execute the start / stop control and the rotational speed control of the compressor 12 based on the temperature detected by the temperature sensor 37.

  In addition, since the generator 30 is connected to the gas engine 10, the power transmitted from the gas engine 10 to the generator 30 is converted into electric energy, which is converted into three-phase AC power via the AC line 42. It is output to the AC / DC converter 34. This AC / DC conversion unit 34 rectifies the three-phase AC power from the generator 30 by the boost converter and converts it into DC power, and then generates a constant output, 300 V in this embodiment via the DC line 43 for photovoltaic power generation. Output to the power conditioner 40 for use. The DC power input to the power conditioner 40 is converted into predetermined AC power with a specified frequency (in this embodiment, AC 200 V 50 Hz or 60 Hz) and regenerated to the commercial power system 44 via the AC line 45. And electric power is supplied to auxiliary machines, such as the air blower 16, via the air-conditioning electrical equipment part 35 connected to the commercial power system 44.

  Here, as shown in the flowchart of FIG. 3, the control device C determines whether or not the gas engine 10 is driven in step S <b> 1. If the gas engine 10 is being driven, the process proceeds to step S2, and first the current rotational speed of the gas engine 10 is acquired. The control device C stores in advance a maximum power generation amount Pmax that is input to the AC / DC conversion unit 34 according to the rotational speed of the gas engine 10.

  In the present embodiment, the rotational speed of the gas engine 10 is controlled to operate the compressor 12 at an optimal rotational speed based on the operating state of the air conditioner 1, that is, the temperature detected by the temperature sensor 37 as described above. Is done. Therefore, the maximum power generation amount Pmax is a power generation amount that can be generated by the power generator 30 with an excess driving force of the gas engine 10 that is driven to operate the compressor 12. That is, the generator 30 driven by the gas engine 10 outputs a high voltage when the rotation speed of the gas engine 10 is high, and the maximum power generation amount Pmax at this time also increases, and when the rotation speed is low. A low voltage is output, and the maximum power generation amount Pmax at this time also decreases.

  Thereby, the control apparatus C acquires the maximum power generation amount Pmax input to the AC / DC conversion unit 34 corresponding to the current rotation speed of the gas engine 10. Then, the control device C proceeds to step S3, detects the power generation amount P currently input from the generator 30 to the AC / DC converter 34, and the power generation amount P is based on the maximum power generation amount Pmax acquired in step S2. Judge whether it is large or not.

  When the AC power generation amount P currently input to the AC / DC conversion unit 34 is larger than the maximum power generation amount Pmax, the process proceeds to step S4, and the solar power generation is performed from the AC / DC conversion unit 34 via the DC line 43. The current flowing through the power conditioner 40 is limited by one step (predetermined one step).

  Specifically, the three-phase AC power input from the generator 30 to the AC / DC converter 34 is rectified and converted to 300V DC power, and the AC / DC converter 34 generates the AC / DC converter based on the current limit signal supplied from the controller C. The direct current output from the DC converter 34 to the power conditioner 40 is ON / OFF controlled (chopper controlled) according to a predetermined duty ratio. As a result, the current flowing from the AC / DC converter 34 to the power conditioner 40 is limited by one step. At this time, the control device C performs control so that the direct current output from the AC / DC converter 34 to the power conditioner 40 follows the point at which the output power becomes maximum in the power conditioner 40 that executes MPPT control. Output. Then, it returns to step S1.

  Thus, by limiting the current flowing from the AC / DC converter 34 to the power conditioner 40 in a stepwise manner, the power conditioner 40 is supplied with the remaining power of the gas engine 10 that drives the compressor 12 by the generator 30. The generated electric power will be supplied. In addition, since the AC / DC converter 34 outputs a current that is controlled so that the power conditioner 40 can efficiently execute the MPPT control, the power conditioner 40 is more efficiently operated. The surplus electric power due to the gas engine drive can be supplied to the system, and efficient operation can be realized.

  On the other hand, if the AC power generation amount P currently input to the AC / DC converter 34 is equal to or less than the maximum power generation amount Pmax in step S3, the process proceeds to step S5, and the output current limit in step S4 is reset. Return to step S1.

  Thereby, according to the rotation speed of the gas engine 10 that is driven and controlled based on the air conditioning load (the operation state of the air conditioner 1), the power conditioner 40 efficiently converts the electric power generated by the surplus driving force into the MPPT. The current can be controlled by the AC / DC converter 34 so that the current can be executed, and can be output to the power conditioner 40.

  Therefore, the power conditioner 40 as the second converter adopted in the present embodiment is a power conditioner for photovoltaic power generation that performs control following the point where the output power is maximum, that is, MPPT control. As described above, the control device C adjusts the DC power output from the AC / DC conversion unit 34 to the power conditioner 40 based on the operating state of the air conditioner 1 so that the MPPT control can be efficiently performed. Thus, it is possible to avoid the disadvantage that a large amount of current is taken into the power conditioner 40, the load on the generator 30 increases, and the driving force for the gas engine 10 to drive the compressor 12 is insufficient.

  Therefore, even if the power conditioner 40 that executes MPPT control is connected to the AC / DC converter 34, the generator 30 can be driven by the surplus power of the gas engine 10 that drives the compressor 12.

  Thereby, the load of the generator 30 increases, the driving force for the gas engine 10 to drive the compressor 12 is insufficient, and the inconvenience of hindering the air conditioning control can be avoided. Thereby, air-conditioning control by the compressor 12 can be executed smoothly, an overload on the gas engine 10 can be avoided, and inconveniences such as engine stop can be avoided beforehand. Moreover, it becomes possible to return the surplus electric power due to the driving of the gas engine 10 to the system efficiently, and air conditioning operation can be realized with high energy consumption efficiency.

  In the present embodiment, the control device C monitors the amount of AC power input from the generator 30 to the AC / DC converter 34, and the AC power amount is stored in advance for the rotational speed of the gas engine 10. Although the direct current output from the AC / DC conversion unit 34 to the power conditioner 40 is limited depending on whether or not the maximum power generation amount Pmax input to the / DC conversion unit 34 is larger, the present invention is not limited to this. For example, the amount of direct current power output from the AC / DC converter 34 to the power conditioner 40 is monitored, and the amount of direct current power stored from the AC / DC converter 34 is stored in advance with respect to the rotational speed of the gas engine 10. Output from the AC / DC converter 34 to the power conditioner 40 depending on whether it is larger than the maximum power generation amount Pmax output to That DC current may be limited.

  Thus, in this embodiment, in the air conditioner 1 in which the compressor 12 is driven by the gas engine 10 and the generator 30 is driven by the surplus driving force, the electric power generated by the generator 30 is generated. It becomes possible to return to the commercial power system by using a highly versatile power conditioner 40 for photovoltaic power generation.

  In particular, according to the present invention, the AC / DC conversion unit 34 on the air conditioner 1 side outputs the power conditioner 40 to the power conditioner 40 based on the operating state of the air conditioner 1 without changing the setting on the power conditioner 40 side. Therefore, the grid interconnection system S of the present application can be constructed using an existing power conditioner, and versatility can be increased.

  In addition, in the said Example, although the power conditioner for solar power generation is used as a 2nd converter, it is not limited to this, For example, you may use the power conditioner for wind power generation.

S Grid interconnection system 1 Gas heat pump type air conditioner 2 Outdoor unit 3 Indoor unit 10 Gas engine 12 Compressor 14 Clutch (transmission means)
15 Indoor heat exchanger (use side heat exchanger)
16 Indoor blower 17 Outdoor heat exchanger (heat source side heat exchanger)
18 Outdoor blower 25 Fuel supply pipe 30 Generator 34 AC / DC conversion unit 40 Power conditioner for solar power generation 40A Inverter circuit 41 Commercial power supply 42 AC line 43 DC line 44 Commercial power system (AC line)

Claims (1)

Compressor and generator constituting the refrigeration cycle, a gas engine that drives the compressor and the generator, a first converter that converts AC power generated by the generator into DC power, and control A gas heat pump type air conditioner provided with means, and a DC power converted by the first converter is converted into a specified frequency AC power of a system to which the air conditioner is connected and returned to the system. In a grid interconnection system with two converters,
The second converter performs control to follow the point where the output power becomes maximum,
The control means follows the current flowing from the first converter to the second converter based on the operating state of the air conditioner, following the point where the output power of the second converter becomes maximum. A grid interconnection system using a gas heat pump type air conditioner that is controlled in such a manner.

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