JP2022011690A - Compressed air energy storage power-generating unit and compressed air energy storage power-generating method - Google Patents

Abstract

To provide a multi-stage CAES power-generating unit and method which curb a reduction in operation efficiency.SOLUTION: A CAES power-generating unit 1 comprises: a plurality of motors 15; compressors 11 to 14 which are driven by each of the plurality of motors 15 and fluidically connected in multiple stages; a pressure accumulation tank 30 which accumulates compressed air discharged from the compressors 11 to 14; expanders 21 to 24 which are driven with the compressed air supplied from the pressure accumulation tank 30; a generator 25 which is driven by the expanders 21 to 24; inverters 16 and 26 which change rotation speeds of the motors 15 or the generator 25; bypass passages 53, 55 and 57 that bypass the compressors 12 to 14 after an arbitrary stage excluding a first stage with the lowest pressure in a flow passage of the compressed air from the compressors 11 to 14 to the pressure accumulation tank 30; and valves 53a, 55a and 57a which are installed on the bypass passages 53, 55 and 57. In the CAES power generation unit 1, among the compressors 11 to 14 in the multiple stages, the compressors 11 to 13 are arranged in plural.SELECTED DRAWING: Figure 1

Description

The present invention relates to a compressed air storage power generation device and a compressed air storage power generation method.

Power generation using renewable energy such as wind power or solar power depends on weather conditions, so the output may not be stable. To get the required power in a timely manner, it is necessary to use an energy storage system. As an example of such a system, for example, a compressed air energy storage (CAES) power generation device is known.

The CAES power generator uses renewable energy to drive a compressor to produce compressed air, stores the compressed air in a tank, etc., and uses the compressed air to drive a turbine generator to generate electricity when needed. It is a device to do.

Patent Document 1 discloses a multi-stage CAES power generation device. In this CAES power generation device, a bypass flow path capable of bypassing the compressor or expander of each stage is provided in the compressed air flow path. Since the flow path of the compressed air can be switched according to the pressure of the accumulator by the bypass flow path, the number of stages of the compressor and the expander can be appropriately changed. This prevents the compressor and inflator from operating far outside the design compression ratio and design expansion ratio, as compared to the case where the compressor and inflator of all stages are always driven, and improves system efficiency. I am trying.

Japanese Unexamined Patent Publication No. 2017-8867

The CAES power generation device is required to operate according to not only the pressure of the accumulator but also the charge / discharge command. However, if there is only one compressor or expander in each stage as in Patent Document 1, it is not possible to realize operation in line with fine fluctuations in the charge / discharge command, and there is a risk that the operation efficiency will decrease.

An object of the present invention is to suppress a decrease in operating efficiency in a multi-stage CAES power generation device and a CAES power generation method.

The first aspect of the present invention is a compressor driven by a plurality of motors and each of the plurality of motors and fluidly connected to a plurality of stages, and a pressure accumulator for storing compressed air discharged from the compressor. And, at least one expander driven by the compressed air supplied from the accumulator, at least one generator driven by the expander, and the rotation speed of the motor or the generator are changed. And at least one bypass flow path for bypassing the compressor after any stage except the first stage of the lowest pressure stage in the flow path of the compressed air from the compressor to the accumulator. Provided is a compressed air storage power generation device including a valve provided in the bypass flow path, wherein a plurality of the compressors having at least one stage among the compressors having the plurality of stages are arranged.

According to this configuration, the compressor with an appropriate number of stages can be driven by appropriately switching the bypass flow path by opening and closing the valve. Therefore, in a CAES power generation device provided with a multi-stage compressor, it is possible to suppress a decrease in operating efficiency. Further, since a plurality of compressors are provided in at least one stage, the charge amount can be adjusted more finely than in the case where one compressor is provided in each stage. Therefore, it is possible to realize the operation according to the fine fluctuation of the charge command value. Here, the "compressor fluidly connected to a plurality of stages" means two or more compressors fluidly connected in series.

A second aspect of the present invention is to supply from the at least one electric motor, at least one compressor driven by the electric motor, a pressure accumulator for storing compressed air discharged from the compressor, and the accumulator. An expander driven by the compressed air and fluidly connected to a plurality of stages, a plurality of generators driven by the expander, and an inverter that changes the rotation speed of the motor or the generator. In the flow path of the compressed air from the accumulator to the expander, at least one bypass flow path for bypassing the expander after any stage except the first stage of the lowest pressure stage, and the bypass flow. Provided is a compressed air storage power generation device including a valve provided in a path and having a plurality of the expanders having at least one stage among the expanders having the plurality of stages.

According to this configuration, the expander having an appropriate number of stages can be driven by appropriately switching the bypass flow path by opening and closing the valve. Therefore, in a CAES power generation device provided with a multi-stage expander, it is possible to suppress a decrease in operating efficiency. Further, since a plurality of expanders are provided in at least one stage, the amount of power generation can be finely adjusted as compared with the case where one expander is provided in each stage. Therefore, it is possible to realize the operation according to the fine fluctuation of the discharge command value. Here, the "expander fluidly connected to a plurality of stages" refers to two or more expanders fluidly connected in series.

The compressed air storage power generation device calculates the number of stages of use of at least one of the compressor and the expander according to the pressure sensor that measures the internal pressure of the accumulator and the internal pressure of the accumulator measured by the pressure sensor. A control device including a unit for calculating the number of stages used may be further provided.

According to this configuration, the number of used stages can be determined by the number of used stages calculation unit according to the internal pressure of the accumulator unit measured by the pressure sensor.

The control device may further include a drive number calculation unit that calculates at least one drive number of the compressor and the expander so that the rated drive number, which is the number of drives at the rated rotation speed in each stage, is maximized. good.

According to this configuration, the maximum number of drives of at least one of the compressor and the expander to be rated can be secured. Here, the rated operation refers to an operating state in which the compressor or the expander exhibits the best efficiency, and generally refers to an operation in which the maximum output can be exhibited. Therefore, by ensuring the maximum number of rated drives, high operating efficiency of the CAES power generation device can be realized.

The compressor and the expander may be integrally configured as a compression / expansion combined machine, and the electric motor and the generator may be integrally configured as an electric power generation combined machine.

According to this configuration, the installation space can be reduced and the cost can be reduced as compared with the case where the compressor and the expander are separately provided. Similarly, as compared with the case where the motor and the generator are separately provided, the installation space can be reduced and the cost can be reduced.

A third aspect of the present invention comprises using electric power to compress air in a plurality of stages, storing the compressed air, and expanding the stored compressed air to generate power. In compression, a compressed air storage power generation method is used in which compression of any or subsequent stages other than the first stage of the lowest pressure stage is selectively omitted, and air is compressed in parallel in at least one of the plurality of stages. offer.

According to this method, since compression deviating from the rated operation can be suppressed in the same manner as described above, it is possible to suppress a decrease in operating efficiency in the CAES power generation method in which a plurality of stages of compression are performed.

A fourth aspect of the present invention comprises using electric power to compress air, store the compressed air, and expand the stored compressed air in a plurality of stages to generate electricity. In expansion, a compressed air storage power generation method is used in which expansion after any stage other than the first stage of the lowest pressure stage is selectively omitted, and air is expanded in parallel in at least one of the plurality of stages. offer.

According to this method, expansion deviating from the rated operation can be suppressed in the same manner as described above, so that a decrease in operating efficiency can be suppressed in the CAES power generation method in which a plurality of stages of expansion are performed.

According to the present invention, it is possible to suppress a decrease in operating efficiency in a multi-stage CAES power generation device and a CAES power generation method.

The schematic block diagram of the CAES power generation apparatus which concerns on 1st Embodiment of this invention. Configuration diagram of the charging unit. The block diagram of the discharge part. The control block diagram of the CAES power generation device. Flow chart about charging operation. A graph showing the relationship between the internal pressure of the accumulator tank and the charging power. Flow chart about discharge operation. A graph showing the relationship between the internal pressure of the accumulator tank and the discharge power. The schematic block diagram of the 1st modification of the CAES power generation apparatus of FIG. The schematic block diagram of the 2nd modification of the CAES power generation apparatus of FIG. The block diagram of the CAES power generation apparatus which concerns on 2nd Embodiment. The block diagram of the charging part in the modification.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(First Embodiment)
In the compressed air storage (CAES) power generation device 1 shown in FIG. 1, the power generated by the power generation facility 2 using renewable energy such as wind power or solar power is stored in the form of compressed air. Then, the stored compressed air is used to generate electric power when necessary, and power is supplied to the power system.

A transmission unit 2a is attached to the power generation facility 2. The transmission unit 2a transmits the power value generated by the power generation facility 2 to the CAES power generation control device 40.

A transmission unit 3a is attached to the operating organization of the electric power system or the organization 3 that controls the electric power transaction, and the electric power price information is transmitted to the CAES power generation control device 40. The CAES power generation control device 40 generates a charge / discharge command value based on the information received from the transmission unit 2a and the transmission unit 3a, and controls the CAES power generation control device 1.

The charge / discharge command value is generated by the control device 40 and refers to at least one command value of charge and discharge. The charge / discharge command value includes a charge command value and a discharge command value. In the CAES power generation device 1, necessary charging and discharging are performed based on this charge / discharge command value.

The CAES power generation device 1 includes a charging unit 100, a discharging unit 200, a pressure accumulating tank (accumulation unit) 30, and a control device 40.

With reference to FIG. 2, the charging unit 100 includes compressors 11 to 14, a motor (motor) 15, and an inverter 16.

In this embodiment, the compressors 11 to 14 are fluidly connected to the four stages. Specifically, the first-stage compressor 11, the second-stage compressor 12, the third-stage compressor 13, and the fourth-stage compressor 14 are fluidly connected in series in this order. ing. Nine compressors 11 are arranged in parallel on the first stage. In the second stage, three compressors 12 are arranged in parallel. Two compressors 13 are arranged in parallel on the third stage. One compressor 14 is arranged in the fourth stage. The compressors 11 to 14 take in air from the intake ports 11a to 14a, compress the air inside, and discharge the compressed air from the discharge ports 11b to 14b. The "stage" here refers to the number in which the compressor 10 is fluidly connected in series, and this number is counted from the low pressure side. In each stage, the compressor 10 is fluidly connected in parallel, so that air can be compressed in parallel.

In the flow of compressed air, the pressure gradually increases from the first stage upstream to the fourth stage downstream. The mass flow rate of compressed air does not change in each stage, but the volumetric flow rate of compressed air decreases as the pressure increases. Therefore, the number of compressors 11 to 14 is gradually decreasing from the first stage to the fourth stage.

Further, the arrangement mode of the compressors 11 to 14 is not limited to the mode of the present embodiment. Preferably, the compressors are fluidly connected to a plurality of stages and a plurality of compressors are provided in at least one stage. Hereinafter, when the compressors 11 to 14 of each stage are described without distinction, they are also simply referred to as a compressor 10.

The plurality of compressors 10 used in the present embodiment are all the same, for example, a screw type. The compressor 10 includes a pair of male and female screw rotors (not shown) inside, and the screw rotors are mechanically connected to the motor 15. An inverter 16 is electrically connected to the motor 15. The rotation speed of the motor 15 is adjusted by the inverter 16. The inverter 16 is controlled by the control device 40.

With reference to FIG. 3, the discharge unit 200 includes expanders 21 to 24, a generator 25, and an inverter 26.

In this embodiment, the expanders 21 to 24 are fluidly connected to the four stages. Specifically, the first-stage expander 21, the second-stage expander 22, the third-stage expander 23, and the fourth-stage expander 24 are fluidly connected in series in this order. ing. Nine expanders 21 are arranged in parallel on the first stage. In the second stage, three expanders 22 are arranged in parallel. Two expanders 23 are arranged in parallel on the third stage. One expander 24 is arranged in the fourth stage. The expanders 21 to 24 are supplied with compressed air from the air supply ports 21a to 24a, expand the compressed air inside, and exhaust the air from the exhaust ports 21b to 24b. The "stage" here refers to the number in which the expanders 20 are fluidly connected in series, and this number is counted from the low pressure side. In each stage, the expanders 20 are fluidly connected in parallel to expand the air in parallel.

In the flow of compressed air, the pressure gradually decreases from the fourth stage upstream to the first stage downstream. The mass flow rate of the compressed air does not change in each stage, but the volumetric flow rate of the compressed air increases in the low pressure stage. Therefore, the number of expanders 21 to 24 is also gradually increasing from the fourth stage to the first stage.

Further, the arrangement mode of the expanders 21 to 24 is not limited to this. Preferably, the expanders are fluidly connected to a plurality of stages and a plurality of expanders are provided in at least one stage. Further, when the expanders 21 to 24 of each stage are described without distinction, they are also simply referred to as an expander 20.

The plurality of expanders 20 used in the present embodiment are all the same, for example, a screw type. The expander 20 includes a pair of male and female screw rotors (not shown) inside, and the screw rotors are mechanically connected to the generator 25. An inverter 26 is electrically connected to the generator 25. The rotation speed of the generator 25 is adjusted by the inverter 26. The inverter 26 is controlled by the control device 40.

With reference to FIG. 1, the accumulator tank 30 is, for example, a steel tank. However, the accumulator tank 30 may be in any embodiment capable of storing air. Alternatively, a sealable underground cavity or the like can also be used as the accumulator tank 30. A pressure sensor 31 for measuring the internal pressure is attached to the pressure accumulator tank 30. The pressure value measured by the pressure sensor 31 is transmitted to the control device 40. As the underground cavity, the space pierced by the salt dome has excellent airtightness and is suitable as a storage space for compressed air.

In the present embodiment, the compressors 11 to 14, the accumulator tank 30, and the expanders 21 to 24 are fluidly connected by air pipes 51 to 66.

With reference to FIG. 2, the intake port 11a of the first-stage compressor 11 is open to the outside air through the air pipe 51. The discharge port 11b of the first-stage compressor 11 is fluidly connected to the intake port 12a of the second-stage compressor 12 through the air pipe 52, and the accumulator tank 30 is connected through the air pipe (bypass flow path) 53. Is fluidly connected to. The discharge port 12b of the second-stage compressor 12 is fluidly connected to the intake port 13a of the third-stage compressor 13 through the air pipe 54, and the accumulator tank 30 is connected through the air pipe (bypass flow path) 55. Is fluidly connected to. The discharge port 13b of the third-stage compressor 13 is fluidly connected to the intake port 14a of the fourth-stage compressor 14 through the air pipe 56, and the accumulator tank 30 is connected through the air pipe (bypass flow path) 57. Is fluidly connected to. The discharge port 14b of the fourth stage compressor 14 is fluidly connected to the accumulator tank 30 through the air pipe 58.

Valves 52a to 58a are provided in the air pipes 52 to 58, respectively. The opening and closing of the valves 52a to 58a is controlled by the control device 40. By opening and closing the valves 52a to 58a, in the flow path of the compressed air from the compressors 11 to 14 to the accumulator tank 30, it becomes possible to bypass the compressors 12 to 14 after any stage except the first stage of the lowest pressure stage. ing.

With reference to FIG. 3, the accumulator tank 30 is fluidly connected to the air supply port 24a of the expander 24 in the fourth stage through the air pipes 59 and 63, and the air pipes (bypass flow paths) 60 to 62 are connected. They are fluidly connected to the air supply ports 21a to 23a of the expanders 21 to 23 in the first to third stages, respectively. The exhaust port 24b of the fourth-stage expander 24 is fluidly connected to the air supply port 23a of the third-stage expander 23 through the air pipe 64. The exhaust port 23b of the third-stage expander 23 is fluidly connected to the air supply port 22a of the second-stage expander 22 through the air pipe 65. The exhaust port 22b of the second-stage expander 22 is fluidly connected to the air supply port 21a of the first-stage expander 21 through an air pipe 66. The exhaust port 21b of the first-stage expander 21 is open to the outside air through the air pipe 67.

Valves 59a to 66a are provided in the air pipes 59 to 66, respectively. The opening and closing of the valves 59a to 65a is controlled by the control device 40. By opening and closing the valves 59a to 66a, it becomes possible to bypass the expanders 22 to 24 of any stage or later except the first stage of the lowest pressure stage in the flow path of the compressed air from the accumulator tank 30 to the expanders 21 to 24. ing.

The control of the CAES power generation device 1 having the above configuration will be described.

The control device 40 is composed of hardware such as a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory), and software mounted therein.

With reference to FIG. 4, the control device 40 has a receiving unit 41, a used stage number calculation unit 42, a drive number calculation unit 43, a rotation speed calculation unit 44, a valve control unit 45, and an inverter as functional configurations. It includes a control unit 46 and a charge / discharge command calculation unit 47. These are realized by the collaboration between the processor, which is a hardware resource, and the program, which is software.

The receiving unit 41 receives the generated power value transmitted from the transmitting unit 2a. Further, the receiving unit 41 receives information on the electric power price from the transmitting unit 3a. Since the charge / discharge command value needs to be changed over time, reception by the receiving unit 41 is continuously performed at predetermined time intervals. Further, when the information regarding the electric power price is determined in advance on the previous day or the like, the electric power price information determined on the previous day may be used instead of the real-time electric power price information.

The number of used stages calculation unit 42 calculates the number of used stages of the compressor 10 and the expander 20 according to the pressure value measured by the pressure sensor 31. The number of stages used here indicates the number of stages from the first stage to the number of stages of the compressor 10 or the expander 20 to be used. By adjusting the number of stages used according to the pressure of the accumulator tank 30 in this way, it is possible to suppress a decrease in the operating efficiency of the CAES power generation device 1 as follows. If the number of stages used is determined regardless of the internal pressure of the accumulator tank 30, the operating efficiency of the CAES power generation device 1 may decrease. For example, if the compressors 10 of all stages are driven when the internal pressure of the accumulator tank 30 is extremely low, many compressors 10 are operated in a state deviating from the rating, and the operating efficiency is lowered. Similarly, if the expanders 20 at all stages are driven when the internal pressure of the accumulator tank 30 is extremely low, many expanders 20 are operated in a state deviating from the rating, and the operating efficiency is lowered. Therefore, such a decrease in operating efficiency of the CAES power generation device 1 can be suppressed.

In the charging operation, the conditional expression (Pc _n-1 <P ≦ Pc _n ) is satisfied by the used stage number calculation unit 42 based on the rated pressure Pc _n of the nth stage compressor and the internal pressure P of the accumulator tank 30. The natural number n is searched. Then, based on the searched natural number n, the number of stages used in the compressor is calculated as n. Here, the rated discharge pressure means the discharge pressure of the compressor in the rated operating state. When the internal pressure P of the accumulator tank 30 is equal to or less than the rated discharge pressure Pc ₁ of the first stage compressor 11, the number of stages of the compressor used is calculated to be one stage. When the internal pressure P of the accumulator tank 30 is equal to or less than the rated discharge pressure Pc ₄ of the fourth-stage compressor 14 and higher than the discharge pressure Pc ₃ of the third-stage compressor 13, the number of stages used in the compressor is calculated to be four. ..

In the discharge operation, the rated air pressure Pe _m-1 of the m-1st stage expander, the rated air pressure Pe _m of the mth stage expander, and the internal pressure P of the accumulator tank 30 are used by the number of stages used calculation unit 42. Based on the above, a natural number _m satisfying the conditional expression (Pem _-1 <P≤Pem) is searched for. Then, based on the searched natural number m, the number of stages used by the expander is calculated as m. Here, the rated air pressure means the air pressure of the expander in the rated operating state. When the internal pressure P of the accumulator tank 30 is equal to or less than the rated air pressure Pe ₁ of the first-stage expander 21, the number of stages used by the expander is calculated to be one. When the internal pressure P of the accumulator tank 30 is less than the rated air pressure Pe ₄ of the fourth-stage expander 24 and lower than the discharge pressure Pc ₃ of the third-stage expander 23, the number of stages used by the expander is calculated to be four. ..

The drive number calculation unit 43 calculates the number of drives of the compressor 10 and the expander 20 in each stage. In the present embodiment, the number of drives of the compressor 10 and the number of drives of the expander 20 are calculated as follows so that the charge / discharge command value determined by the control device 40 is satisfied and the rated drive number is maximized in each stage. Here, the number of drives means the number of compressors 10 or expanders 20 that are driven regardless of the rotation speed. The rated operating number means the number of compressors 10 or expanders 20 that rotate at the rated rotation speed.

In the charging operation, the value obtained by dividing the charging command value Wcd by the maximum charging power Wcmax when all the compressors of the number of used stages calculated by the used stage number calculation unit 42 are rated-operated is calculated as the charge ratio Rc ( Rc = Wcd / Wcmax). Here, the number of installed compressors in the nth stage is Mc _n . When the integer part Ic and the decimal part Dc exist in the value (Mc _n × Rc) obtained by integrating the charge ratio Rc into the number Mc _n , the number of driven compressors in the nth stage is calculated to be Ic + 1. When only the integer part Ic exists in the value (Mc _n × Rc) obtained by integrating the charge ratio Rc into the number Mc _n (that is, when the decimal part Dc is zero), the number of driven compressors in the nth stage is Ic. Is calculated. In this embodiment, four-stage compressors 11 to 14 are provided, and Mc ₁ = 9, Mc ₂ = 3, Mc ₃ = 2, and Mc ₄ = 1. Therefore, when n is 1 to 4, the number of driven compressors 11 to 14 in the first to fourth stages is calculated, respectively. Further, among the n-th stage drive units calculated here, the Ic unit is treated as the rated drive number in the n-th stage as described later.

In the discharge operation, the value obtained by dividing the charge command value Wed by the maximum discharge power Wemax when all the expanders of the number of used stages calculated by the number of used stages calculation unit 42 are rated-operated is calculated as the discharge ratio Re (the discharge ratio Re). Re = Wed / Wemax). Here, the number of _m -th stage expanders installed is defined as Mem. When the integer part Ie and the decimal part De exist in the value ( _Mem × Re) obtained by integrating the discharge ratio Re into the number of units Mem, the number of driven units of the _m -th stage expander is calculated as Ie + 1. When only the integer part Ie exists in the value ( _Mem × Re) obtained by integrating the discharge ratio Re into the number of units Me _m (that is, when the decimal part De is zero), the number of driven units of the m-th stage expander is the Ie unit. Is calculated. In this embodiment, four-stage expanders 21 to 24 are provided, and Me ₁ = 9, Me ₂ = 3, Me ₃ = 2, and Me ₄ = 1. Therefore, when m is 1 to 4, the number of drives of the expanders 21 to 24 in the first to fourth stages is calculated, respectively. Further, among the number of driven units in the m-th stage calculated here, the IE unit is treated as the rated number of driven units in the m-th stage as described later.

The rotation speed calculation unit 44 calculates the rotation speeds of the compressor 10 and the expander 20 in each stage so as to satisfy the charge / discharge command value. In the present embodiment, the rotation speed of the rated drive number is set to the rated rotation speed. Further, the rotation speed of a number other than the rated drive number (that is, 0 or 1) is calculated as follows so as to satisfy the charge command value and the discharge command value based on the charge ratio Rc and the discharge ratio Re, respectively. Will be done.

In the charging operation, when the integer part Ic and the decimal part Dc exist in the value (Mc _n × Rc) obtained by integrating the charge ratio Rc into the number Mc _n in the nth stage, the rotation speed of the compressor of the Ic unit is the rated rotation speed. It is set as a number, and the rotation speed of the remaining one unit is calculated as the rated rotation speed × Dc. Further, in the nth stage, when only the integer part Ic exists in the value (Mc _n × Rc) obtained by integrating the charge ratio Rc into the number Mc _n (that is, when the decimal part Dc is zero), the compressors of Ic units. The rotation speed of is the rated rotation speed. In the present embodiment, such a calculation is performed when n is 1 to 4, and the rotation speeds of the compressors 11 to 14 in the first to fourth stages are calculated, respectively.

In the discharge operation, when the integer part Ie and the decimal part De exist in the value ( _Mem × Re) obtained by integrating the charge ratio Re into the number of units Mem in the _mth stage, the rotation speed of the expander of the Ie unit is the rated rotation. It is set as a number, and the rotation speed of the remaining one unit is calculated as the rated rotation speed × De. Further, in the _m -th stage, when only the integer part Ie exists in the value ( _Mem × Re) obtained by integrating the charge ratio Re into the number of units Mem (that is, when the decimal part De is zero), the expander of the Ie unit. The number of rotations of is the rated rotation number. In the present embodiment, such a calculation is performed when m is 1 to 4, and the rotation speeds of the expanders 21 to 24 in the first to fourth stages are calculated, respectively.

In this way, the number of stages of the compressor 10 used, the number of drives of each stage, and the number of rotations are determined. Similarly, the number of stages used, the number of drives of each stage, and the number of rotations of the expander 20 are determined. The above is a premise that the compressor and the expander are operated at 0 to 100%, but the lower limit rotation speed of the compressor and the expander may be determined in consideration of the discharge temperature rise and the inverter design. For example, when the rated rotation speed × Dc or the rated rotation speed × De is below the lower limit, the remaining one unit may be rotated at the lower limit rotation speed, or the power may be adjusted by two units.

The valve control unit 45 opens and closes the valves 52a to 66a so that the compressor 10 and the expander 20 can be driven by the number of stages used calculated as described above.

In the charging operation, when the number of stages used is calculated to be one, the valve 53a is opened and the valves 52a, 54a to 58a are closed. As a result, only the first-stage compressor 11 can be driven. When the number of stages used is calculated to be two, the valves 52a and 55a are opened, and the valves 53a, 54a, 56a to 58a are closed. As a result, only the first and second stage compressors 11 and 12 can be driven. When the number of stages used is calculated to be 3, the valves 52a, 54a, 57a are opened and the valves 53a, 55a, 56a, 58a are closed. As a result, only the compressors 11 to 13 in the first to third stages can be driven. When the number of stages used is calculated to be 4, the valves 52a, 54a, 56a, 58a are opened and the valves 53a, 55a, 57a are closed. As a result, the compressors 11 to 14 in the first to fourth stages can be driven.

In the discharge operation, when the number of stages used is calculated to be one, the valves 59a, 60a, 66a are opened and the valves 61a to 65a are closed. As a result, only the first-stage expander 21 can be driven. When the number of stages used is calculated to be two, the valves 59a, 61a, 65a, 66a are opened, and the valves 60a, 62a to 64a are closed. As a result, only the first and second stage expanders 21 and 22 can be driven. When the number of stages used is calculated to be 3, the valves 59a, 62a, 64a to 66a are opened, and the valves 60a, 61a, 63a are closed. As a result, only the first to third stage expanders 21 to 23 can be driven. When the number of stages used is calculated to be 4, the valves 59a, 63a to 66a are opened, and the valves 60a to 62a are closed. As a result, the expanders 21 to 24 in the first to fourth stages can be driven.

The inverter control unit 46 controls the inverters 16 and 26 so as to drive the compressor 10 and the expander 20 (motor 15 and generator 25), respectively, with the number of drives and the number of revolutions calculated as described above.

The charge / discharge command calculation unit 47 calculates the charge / discharge command value based on the information received by the reception unit 41.

FIG. 5 shows a flowchart relating to the charging operation.

In the charging operation, first, the internal pressure of the accumulator tank 30 is detected by the pressure sensor 31 (step S5-1). Then, the number of used stages calculation unit 42 calculates the number of used stages of the compressor 10 according to the internal pressure of the accumulator tank 30 as described above (step S5-2). Then, the valve control unit 45 controls the valves 52a to 58a so as to drive the compressor 10 having the number of stages used calculated as described above (step S5-3). Next, the charge / discharge command calculation unit 47 determines based on the information received by the reception unit 41 (the electric energy of the wind power plant transmitted from the transmission unit 2a and the information of the electric power price transmitted from the transmission unit 3a). The charged charging command is set (step S5-4). Then, the drive number calculation unit 43 and the rotation speed calculation unit 44 determine the drive number and the rotation speed of the compressor 10 in each stage as described above (step S5-5). Then, the inverter 16 is controlled by the inverter control unit 46 so as to drive the compressor 10 at a determined number of drives and rotation speed (step S5-6).

FIG. 6 is a graph showing the relationship between the internal pressure of the accumulator tank 30 and the charging power. In FIG. 6, the horizontal axis represents the internal pressure (MPaG) of the accumulator tank 30, and the vertical axis represents the charging power (kW) of the CAES power generation device 1. The lower line in the graph shows the minimum charge power Wcmin when the compressor 10 is driven at the minimum rotation speed, and the upper line shows the maximum charge power Wcmax when the compressor 10 is driven at the rated rotation speed. There is. Therefore, the CAES power generation device 1 can be charged and operated between these lines Wcmax and Wcmin.

In the present embodiment, the rated discharge pressure Pc ₁ of the first-stage compressor 11 is 0.98 MPaG, the rated discharge pressure Pc ₂ of the second-stage compressor 12 is 2.0 MPaG, and the third-stage compression. The rated discharge pressure Pc ₃ of the machine 13 is 3.2 MPaG, and the rated discharge pressure Pc ₄ of the fourth stage compressor 14 is 4.4 MPaG (not shown). By making the differential pressures between the stages substantially equal in this way, the parts of the compressor 10 that depend on the differential pressure can be partially shared. Therefore, mass production of shared parts and unification of assembly work can be achieved, and cost can be reduced. This also applies to the expander 20.

As shown at point P1 as an example in FIG. 6, when the internal pressure of the accumulator tank 30 is 2.5 MPaG, the conditional expression of 2.0 (= Pc ₂ ) <2.5 ≦ 3.2 (= Pc ₃ ). Is satisfied, the number of stages used is calculated to be three. Therefore, the compressors 11 to 13 of the first to third stages are driven.

With reference to FIG. 6, when the internal pressure of the accumulator tank 30 is 2.5 MPaG, the maximum charge power Wcmax is 2350 kW. When 1175 kW is given as the charge command value Wc as shown at the point P1, the charge ratio Rc (= Wcd / Wcmax) is calculated to be 0.5. Therefore, the integer part 4 (= Ic) and the decimal part 0.5 are added to the value 4.5 obtained by integrating the charge ratio 0.5 (= Rc) into the 9 units (= Mc ₁ ) installed in the first stage compressor 11. Since (= Dc) exists, the number of driven compressors 11 in the first stage is calculated to be 5 (= Ic + 1) units. Further, 4 out of 5 units are driven at the rated rotation speed, and the remaining 1 unit is driven at the rated rotation speed × 0.5 rotation speed. Similarly, in the second stage compressor 12, the number of driven units is calculated to be two, one of the two units is driven at the rated rotation speed, and the remaining one is the rated rotation speed × 0.5 rotation speed. Driven by. Similarly, in the third stage compressor 13, the number of driven units is calculated to be one, and one of them is driven at the rated rotation speed. In this way, the compressor 10 is driven so as to satisfy the charging command value received by the receiving unit 41 and to maximize the rated drive number in each stage.

FIG. 7 shows a flowchart relating to the discharge operation.

In the discharge operation, first, the internal pressure of the accumulator tank 30 is detected by the pressure sensor 31 (step S7-1). Then, the number of used stages calculation unit 42 calculates the number of used stages of the expander 20 according to the internal pressure of the accumulator tank 30 as described above (step S7-2). Then, the valve control unit 45 controls the valves 59a to 65a so as to drive the expander 20 having the number of stages used calculated as described above (step S7-3). Next, the discharge command determined by the charge / discharge command calculation unit 47 is set based on the information received by the reception unit 41 (step S7-4). Then, the drive number calculation unit 43 and the rotation speed calculation unit 44 determine the drive number and the rotation speed of the expander 20 in each stage as described above (step S7-5). Then, the inverter 26 is controlled by the inverter control unit 46 so as to drive the expander 20 at a determined number of drives and rotation speed (step S7-6).

FIG. 8 is a graph showing the relationship between the internal pressure of the accumulator tank 30 and the discharge power. In FIG. 8, the horizontal axis represents the internal pressure (MPaG) of the accumulator tank 30, and the vertical axis represents the discharge power (kW) of the CAES power generation device 1. The lower line in the graph shows the minimum discharge power Wemin when the expander 20 is driven at the minimum rotation speed, and the upper line shows the maximum discharge power Wemax when the expander 20 is driven at the rated rotation speed. There is. Therefore, the CAES power generation device 1 can perform discharge operation between these lines Wemax and Wemin.

In the present embodiment, the rated air pressure Pe ₁ of the first-stage inflator 21 is 0.98 MPaG, the rated air pressure Pe ₂ of the second-stage inflator 22 is 2.0 MPaG, and the third-stage expansion The rated air pressure Pe ₃ of the machine 23 is 3.2 MPaG, and the rated air pressure Pe ₄ of the fourth-stage expander 24 is 4.4 MPaG (not shown).

As shown at point P2 as an example in FIG. 8, when the internal pressure of the accumulator tank 30 is 2.5 MPaG, the conditional expression of 2.0 (= Pe ₂ ) <2.5 ≦ 3.2 (= Pe ₃ ). Is satisfied, the number of stages used is calculated to be three. Therefore, the first to third stage expanders 21 to 23 are driven.

With reference to FIG. 8, when the internal pressure of the accumulator tank 30 is 2.5 MPaG, the maximum discharge power Wemax is 2000 kW. When 1000 kW is given as the discharge command value We as shown at the point P2, the discharge ratio Re (= Wed / Wemax) is calculated as 0.5. Therefore, the integer part 4 (= Ie) and the decimal part 0.5 are added to the value 4.5 obtained by integrating the discharge ratio 0.5 (= Re) into the 9 units (= Me ₁ ) installed in the first stage expander 21. Since (= De) exists, the number of drives of the first-stage expander 21 is calculated to be 5 (= Ie + 1) units. Further, 4 out of 5 units are driven at the rated rotation speed, and the remaining 1 unit is driven at the rated rotation speed × 0.5 rotation speed. Similarly, in the second-stage expander 22, the number of driven units is calculated to be two, one of the two units is driven at the rated rotation speed, and the remaining one is the rated rotation speed × 0.5 rotation speed. Driven by. Similarly, in the third-stage expander 23, the number of driven units is calculated to be one, and one of them is driven at the rated rotation speed. In this way, the expander 20 is driven so as to satisfy the discharge command value received by the receiving unit 41 and to maximize the rated drive number in each stage.

According to the CAES power generation device 1 of the present embodiment, the following effects are exhibited.

By appropriately switching the bypass flow paths 53, 55, 57 by opening and closing the valves 52a to 58a, the compressor 10 having an appropriate number of stages can be driven. Therefore, in the CAES power generation device 1 provided with the multi-stage compressor 10, it is possible to suppress a decrease in operating efficiency. Further, since a plurality of compressors 10 are provided in at least one stage, the charge amount can be finely adjusted as compared with the case where one compressor 10 is provided in each stage. Therefore, it is possible to realize the operation according to the fine fluctuation of the charge command value.

Further, by appropriately switching the bypass flow paths 60 to 62 by opening and closing the valves 59a to 66a, the expander 20 having an appropriate number of stages can be driven. Therefore, in the CAES power generation device 1 provided with the multi-stage expander 20, it is possible to suppress a decrease in operating efficiency. Further, since a plurality of expanders 20 are provided in at least one stage, the amount of power generation can be finely adjusted as compared with the case where one expander 20 is provided in each stage. Therefore, it is possible to realize the operation according to the fine fluctuation of the discharge command value.

Further, the number of used stages can be determined by the number of used stages calculation unit 42 according to the internal pressure of the accumulator tank 30 measured by the pressure sensor 31. If the number of stages used is determined regardless of the internal pressure of the accumulator tank 30, the operating efficiency of the CAES power generation device 1 may decrease. For example, if the compressors 11 to 14 of all stages are driven when the internal pressure of the accumulator tank 30 is extremely low, many compressors are operated in a state deviating from the rating, and the operating efficiency is lowered. Similarly, if the expanders 21 to 24 of all stages are driven when the internal pressure of the accumulator tank 30 is extremely low, many expanders are operated in a state deviating from the rating, and the operating efficiency is lowered. Therefore, since the number of stages used can be adjusted according to the internal pressure of the accumulator tank 30, it is possible to suppress a decrease in the operating efficiency of the CAES power generation device 1.

Further, the drive number calculation unit 43 and the rotation speed calculation unit 44 can secure the maximum number of drives of the compressor 10 and the expander 20 to be rated and operate, and can satisfy the charge / discharge command value. Therefore, by ensuring the maximum number of rated drives, high operating efficiency of the CAES power generation device 1 can be realized.

(First modification)
FIG. 9 shows a schematic configuration diagram of a first modification of the CAES power generation device of FIG.

In the CAES power generation device 1 of this modification, the configuration of the discharge unit 200 is different from that of the above embodiment, but the configuration other than the discharge unit 200 is substantially the same as that of the above embodiment. In this modification, the discharge unit 200 is composed of only one expander 20, one generator 25, and one inverter 26. In other words, the charging unit 100 is composed of a multi-stage compressor 10, and the discharging unit 200 is composed of a single-stage expander 20. Therefore, in the discharge unit 200, there is only one flow path for compressed air.

The control of the charging operation of the CAES power generation device 1 of this modification is substantially the same as the above-described embodiment shown in FIGS. 5 and 6. Unlike the above embodiment, the control of the discharge operation does not switch the flow path of the compressed air, and only the rotation speed of the expander 20 is adjusted according to the discharge command value. In this case, the expander 20 can use a large turbo expander.

(Second modification)
FIG. 10 shows a schematic configuration diagram of a second modification of the CAES power generation device of FIG.

In the CAES power generation device 1 of this modification, the configuration of the charging unit 100 is different from that of the above embodiment, but the configuration other than the charging unit 100 is substantially the same as that of the above embodiment. In this modification, the charging unit 100 is composed of only one compressor 10, one motor 15, and one inverter 16. In other words, the discharge unit 200 is composed of a multi-stage expander 20, and the charge unit 100 is composed of a single-stage compressor 10. Therefore, in the charging unit 100, there is only one flow path for compressed air. In this case, the compressor 10 can use a large reciprocating compressor or a turbo compressor.

The control of the charging operation of the CAES power generation device 1 of this modification is substantially the same as that of the above-described embodiment shown in FIGS. 7 and 8. Unlike the above embodiment, the control of the charging operation does not switch the flow path of the compressed air, and only the rotation speed of the compressor 10 is adjusted according to the charging command value.

As shown in the first embodiment, the first modification, and the second modification, the multi-stage configuration in the CAES power generation device 1 can be adopted in at least one of the charging unit 100 and the discharging unit 200. Further, the number of stages of the charging unit 100 or the discharging unit 200 is not limited to four, and may be two, three, or five or more.

(Second Embodiment)
In the CAES power generation device 1 of the second embodiment shown in FIG. 11, the charging unit 100 and the discharging unit 200 are integrally configured. Except for this, it is substantially the same as the CAES power generation device 1 of the first embodiment. Therefore, the description of the same part as that of the first embodiment may be omitted.

In the present embodiment, the compressors 11 to 14 (see FIG. 2) and the expanders 21 to 24 (see FIG. 3) in the first embodiment are integrally configured as compression / expansion combined machines 71 to 74, respectively. Further, the motor 15 and the generator 25 in the first embodiment are integrally configured as an electric power generation combined machine 75.

In this embodiment, the compression / expansion machines 71 to 74 are fluidly connected in four stages. Specifically, the first-stage compression / expansion combined machine 71, the second-stage compression / expansion combined machine 72, the third-stage compression / expansion combined machine 72, and the fourth-stage compression / expansion combined machine 74 are described above. They are fluidly connected in series in order. Nine compression / expansion machines 71 are arranged in parallel on the first stage. In the second stage, three compression / expansion machines 72 are arranged in parallel. In the third stage, two compression / expansion machines 73 are arranged in parallel. In the fourth stage, one compression / expansion machine 74 is arranged.

In the flow of compressed air, the pressure increases stepwise from the first stage to the fourth stage, so the mass flow rate of the compressed air does not change in each stage, but the volume flow rate of the compressed air decreases as the pressure increases. .. Therefore, the number of compression / expansion machines 71 to 74 is gradually decreasing from the first stage to the fourth stage.

In the charging operation, the compression / expansion combined machines 71 to 74 take in air from the low pressure ports 71a to 74a, compress the air inside, and discharge the compressed air from the high pressure ports 71b to 74b. In the discharge operation, the compression / expansion combined machines 71 to 74 are supplied with air from the high pressure ports 71b to 74b, expand the compressed air inside, and exhaust the air from the low pressure ports 71a to 74a. That is, in the charging operation and the discharging operation, the air flow is in the opposite direction.

The arrangement mode of the compression / expansion combined machines 71 to 74 is not limited to this. Preferably, the compression / expansion combined machines 71 to 74 are fluidly connected to a plurality of stages, and a plurality of the compression / expansion machines 71 to 74 are provided in at least one stage. Further, when the compression / expansion combined machines 71 to 74 of each stage are described without distinction, they are also simply referred to as a compression / expansion combined machine 70.

The plurality of compression / expansion machines 70 used in the present embodiment are all the same, for example, a screw type. The compression / expansion combined machine 70 includes a pair of male and female screw rotors (not shown) inside, and the screw rotors are mechanically connected to the electric power generation combined machine 75. The electric power generation combined machine 75 is electrically connected to the inverter 76. The rotation speed of the electric power generation combined machine 75 is adjusted by the inverter 76. The inverter 76 is controlled by the control device 40.

In the present embodiment, the compression / expansion combined machines 71 to 74 and the accumulator tank 30 are fluidly connected by air pipes 81 to 89.

The low pressure port 71a of the first-stage compression / expansion machine 71 is open to the outside air through the air pipe 81. The high-pressure port 71b of the first-stage compression / expansion machine 71 is fluidly connected to the low-pressure port 72a of the second-stage compression / expansion machine 72 through the air pipe 82, and the air pipe (bypass flow path) 83, It is fluidly connected to the accumulator tank 30 through 89. The high pressure port 72b of the second stage compression / expansion combined machine 72 is fluidly connected to the low pressure port 73a of the third stage compression / expansion combined machine 73 through the air pipe 84, and the air pipe (bypass flow path) 85, It is fluidly connected to the accumulator tank 30 through 89. The high pressure port 73b of the third stage compression / expansion combined machine 73 is fluidly connected to the low pressure port 74a of the fourth stage compression / expansion combined machine 74 through the air pipe 86, and the air pipe (bypass flow path) 87, It is fluidly connected to the accumulator tank 30 through 89. The high-pressure port 74b of the fourth-stage compression / expansion combined machine 74 is fluidly connected to the accumulator tank 30 through the air pipes 88 and 89.

Valves 82a to 89a are provided in the air pipes 82 to 89, respectively. The opening and closing of the valves 82a to 89a is controlled by the control device 40. By opening and closing the valves 82a to 89a, in the flow path of the compressed air between the compression / expansion machines 71 to 74 and the accumulator tank 30, the compression / expansion machines 72 to after any stage except the first stage of the lowest pressure stage. It is possible to bypass 74.

The control of the CAES power generation device 1 of the present embodiment is substantially the same as that of the first embodiment. However, in the charging operation, the compression / expansion combined machine 70 operates as a compressor and the electric power generation combined machine 75 operates as a motor. In the discharge operation, the compression / expansion combined machine 70 operates as an expander, and the electric power generation combined machine 75 operates as a generator 25.

According to the CAES power generation device 1 of the present embodiment, the operation and effect are substantially the same as those of the first embodiment. Further, as compared with the case where the compressor and the expander are separately provided, the installation space can be reduced and the cost can be reduced. Similarly, the installation space can be reduced and the cost can be reduced as compared with the case where the motor and the generator are separately provided.

Although the specific embodiment of the present invention and the modification thereof have been described above, the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention.

For example, some of the plurality of valves 52a to 66a and 82a to 89a may be integrally configured by using a three-way valve or the like.

Further, the outputs of all the compressors 10 may not be the same, and compressors having different outputs may be used. FIG. 12 shows a modified example of the charging unit 100 of FIG. With reference to FIG. 12, for example, a large compressor 17 having a relatively large output may be arranged in the first stage. The large compressor 17 has three times the output of the other first-stage compressor 11. Therefore, the three compressors 11 of the charging unit 100 shown in FIG. 2 can be replaced with one large compressor 17. In this case, it is preferable to prioritize and drive the compressor so as to increase the operating efficiency of the CAES power generation device 1 according to the operating characteristics of the compressor and the motor and the charging command value. For example, the large compressor 17 is preferentially used for a charge command value large enough to use the large compressor 17, and another charge command value is used for a small charge command value such that the large compressor 17 cannot be used. The first-stage compressor 11 may be used. In FIG. 12, the compressor has been described as an example, but the same applies to the expander 20 and the compression / expansion combined machine 70.

1 CAES power generation device (compressed air storage power generation device)
2 Power generation equipment 2a Transmitter 3 Consumer equipment 3a Transmitter 100 Charger 10-14 Compressor 11a-14a Intake port 11b-14b Discharge port 15 Motor (motor)
16 Inverter 17 Large compressor 200 Discharge section 20-24 Expander 21a-24a Air supply port 21b-24b Exhaust port 25 Generator 26 Inverter 30 Accumulation tank (accumulation section)
31 Pressure sensor 40 Control device (CAES power generation control device)
41 Receiving unit 42 Number of stages used calculation unit 43 Number of drives calculation unit 44 Rotation speed calculation unit 45 Valve control unit 46 Inverter control unit 47 Charging / discharging command calculation unit 51 to 67 Air piping 52a to 66a Valve 70 to 74 Compression / expansion combined machine 71a to 74a Low voltage port 71b to 74b High voltage port 75 Electric power generation combined machine 76 Inverter 81 to 89 Air piping 82a to 89a Valve

Claims (7)

With multiple motors,
A compressor driven by each of the plurality of motors and fluidly connected to a plurality of stages,
A pressure accumulator that stores compressed air discharged from the compressor,
At least one expander driven by the compressed air supplied from the accumulator and
With at least one generator driven by the expander,
An inverter that changes the rotation speed of the motor or the generator,
In the flow path of the compressed air from the compressor to the accumulator, at least one bypass flow path for bypassing the compressor after any stage except the first stage of the lowest pressure stage.
A valve provided in the bypass flow path is provided.
A compressed air storage power generation device in which a plurality of the compressors having at least one stage among the compressors having a plurality of stages are arranged. With at least one motor,
With at least one compressor driven by the motor,
A pressure accumulator that stores compressed air discharged from the compressor,
An expander driven by the compressed air supplied from the accumulator and fluidly connected to a plurality of stages.
A plurality of generators driven by the expander,
An inverter that changes the rotation speed of the motor or the generator,
In the flow path of the compressed air from the accumulator to the expander, at least one bypass flow path for bypassing the expander after any stage except the first stage of the lowest pressure stage.
A valve provided in the bypass flow path is provided.
A compressed air storage power generation device in which a plurality of the expanders having at least one stage among the expanders having the plurality of stages are arranged. A pressure sensor that measures the internal pressure of the accumulator and
1. 2. The compressed air storage power generation device according to 2. The control device calculates the number of drives of at least one of the compressor and the expander so that the rated number of drives, which is the number of units driven at the rated rotation speed in each stage, is maximized. The compressed air storage power generation device according to claim 3, further comprising. The compressor and the expander are integrally configured as a compression / expansion combined machine.
The compressed air storage power generation device according to any one of claims 1 to 4, wherein the motor and the generator are integrally configured as an electric power generation combined machine. Using electric power to compress air in multiple stages,
Stores compressed air,
Including generating electricity by expanding the stored compressed air,
In the multiple-stage compression, compression after any stage other than the first stage of the lowest pressure stage is selectively omitted.
A compressed air storage power generation method in which air is compressed in parallel in at least one of the plurality of stages. Uses electricity to compress air and
Stores compressed air,
It includes generating electricity by expanding the stored compressed air in multiple stages.
In the expansion of the plurality of stages, expansion after any stage other than the first stage of the lowest pressure stage is selectively omitted.
A compressed air storage power generation method in which air is expanded in parallel in at least one of the plurality of stages.

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