JP7219819B2 - Power supply system and its control method and device - Google Patents

Description

The present invention relates to a power supply system comprising a low-capacity, high-output power storage device connected to a generator and a power load.

Conventionally, in a power supply system that supplies power from a generator to a power load, surplus power is charged to a power storage device connected to the generator and the power load, and when the power load runs short of power, the power is stored in the power storage device. There are some that are configured to discharge the stored power and supply it to the power load. Patent Documents 1 and 2 disclose methods for charging and discharging such an electricity storage device.

In Patent Document 1, a generator driven by an engine, a first inverter that controls the generator, an electric motor, a second inverter that drives the electric motor, and the first and second inverters are connected via a converter, A hybrid construction machine including a power storage device whose charge and discharge are controlled by a converter is disclosed. In this construction machine, an output upper limit value and an output lower limit value of the power storage device are determined in consideration of a target SOC determined so as to maintain the SOC (state of charge) of the power storage device within a predetermined range. This avoids overcharging and overdischarging of the storage device.

Patent Document 2 discloses a plug that includes a generator driven by an engine, a power storage device that stores power generated by the power generator, and an external power supply unit that supplies the power stored in the power storage device to the outside of the vehicle. An in-hybrid vehicle is disclosed. In this vehicle, the engine is started when the SOC of the power storage device reaches the lower limit value of the allowable range while power is supplied from the external power supply unit to the outside, and the engine is stopped when the SOC of the power storage device reaches the upper limit value of the allowable range. The SOC of the power storage device increases according to the amount of power generated.

Japanese Patent Application Laid-Open No. 2010-41828 JP 2015-47972 A

A lithium ion capacitor (hereinafter abbreviated as LIC) is one of the chargeable/dischargeable power storage devices as described above. A LIC is an electricity storage device that combines a positive electrode of an electric double layer capacitor (hereinafter abbreviated as EDLC) and a negative electrode of a lithium ion battery (hereinafter abbreviated as LIB). A LIC has both high energy density and high output density, and is suitable for applications in which charging and discharging are frequently repeated because of its characteristics of being capable of rapid charging and discharging of a large current. On the other hand, the LIC has a smaller capacity than the LIB, and is easily affected by charge/discharge efficiency (=discharge capacity÷charged electricity amount×100). Therefore, the capacity of the LIC, which is determined assuming long-term operation, becomes significantly large. As the capacity of the power storage device increases, the space it occupies increases, and the initial cost and running cost also increase.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power supply system that includes an electricity storage device that is connected to a generator and an electric power load to charge and discharge. It is to propose a technology that can suppress (size).

A control device for a power supply system according to one aspect of the present invention includes:
an engine, a generator that generates power using the motive power of the engine, a power storage device that stores at least one of the power generated by the power generator and regenerated power from the power load, and the power stored in the power storage device and A control device for a power supply system comprising a power supply unit for supplying power generated by the generator to a power load,
The SOC of the electricity storage device is measured, the SOC average value is obtained from the SOC, the generator output target value is determined based on the SOC average value, and the output of the generator is set to the generator output target value. configured to control
The generator output target value is determined to be a predetermined basic value greater than 0 if the SOC average value exceeds a predetermined allowable upper limit value, and if the SOC average value is lower than a predetermined allowable lower limit value, the generator output target value is determined to be higher than the basic value. is determined to be a large correction value, and if the SOC average value is equal to or greater than the allowable lower limit value and equal to or lower than the allowable upper limit value , the current generator output target value is determined, and the generator output target value is set to the basic value and the It is characterized by changing between two values with a correction value .

Further, the power supply system according to one aspect of the present invention includes:
engine and
a generator that generates power using the power of the engine;
a power storage device that stores at least one of the power generated by the generator and the regenerated power from the power load;
a power supply unit for supplying power stored in the power storage device and power generated by the generator to a power load;
and the control device.

Further, a control method for a power supply system according to one aspect of the present invention includes:
an engine, a generator that generates power using the motive power of the engine, a power storage device that stores at least one of the power generated by the power generator and regenerated power from the power load, and the power stored in the power storage device and A control method for a power supply system comprising a power supply unit for supplying power generated by the generator to a power load,
measuring the SOC of the electricity storage device;
obtaining an SOC average value from the SOC;
determining a generator output target value based on the SOC average value; and
controlling the output of the generator in response to the generator output target value;
The generator output target value is determined to be a predetermined basic value greater than 0 if the SOC average value exceeds a predetermined allowable upper limit value, and if the SOC average value is lower than a predetermined allowable lower limit value, the generator output target value is determined to be higher than the basic value. is determined to be a large correction value, and if the SOC average value is equal to or greater than the allowable lower limit value and equal to or lower than the allowable upper limit value , the current generator output target value is determined, and the generator output target value is set to the basic value and the It is characterized by changing between two values with a correction value .

According to the power supply system and its control method and apparatus described above, if the SOC average value decreases, power is supplied from the generator to the power storage device or the power load so as to compensate for the lost power storage amount. As a result, regardless of the number of charge/discharge cycles, the average SOC value is maintained within the allowable range between the allowable lower limit value and the allowable upper limit value. In other words, the simple control of changing the generator output between two values suppresses the effect of charge-discharge efficiency caused by repeated charge-discharge. As a result, the power storage device can repeat charging and discharging while avoiding over-discharging and over-charging.

Since the electric storage device generally maintains the amount of charge in the initial period of operation, it is sufficient to have a capacity and output that satisfy the charge/discharge profile (that is, the required amount of charge/discharge) in the initial period of operation. The number of cells (system size, capacity) can be suppressed.

Also, the electric power generated by the generator is mainly used to supplement the charge/discharge efficiency of the electric storage device. That is, compared to the case of suppressing load fluctuation only by the power generated by the generator, it is possible to reduce the size of the generator included in the power supply system. This can contribute to the reduction of initial cost and fuel consumption for the generator.

Advantageous Effects of Invention According to the present invention, in a power supply system that includes an electricity storage device that is connected to a generator and an electric power load to charge and discharge, the system size of the electricity storage device and the size of the generator can be reduced.

FIG. 1 is a schematic configuration diagram of a water landing pick-up system to which a power supply system according to an embodiment of the present invention is applied. FIG. 2 is a block diagram showing the configuration of the power supply system. FIG. 3 is a functional block diagram of the control device. FIG. 4 is an example of a power load profile for one cycle. FIG. 5 is a flow chart showing the flow of processing by the control device. FIG. 6 is a chart showing simulation results for one cycle. FIG. 7 is a chart showing simulation results from 1 cycle to 480 cycles.

Next, embodiments of the present invention will be described with reference to the drawings. Here, the power supply system 10 according to one aspect of the present invention will be described by applying it to a general landing and recovery system 13 . However, the power supply system 10 is not limited to the water landing system 13, and can be applied to vehicles, construction machines, and the like.

FIG. 1 is a schematic configuration diagram of a water landing pick-up system 13 to which a power supply system 10 according to one embodiment of the present invention is applied. The landing on water lifting and recovering system 13 shown in FIG. 1 suspends the underwater device 12 from a platform 11 floating on the water, and performs landing, lifting, and attitude maintenance of the underwater device 12 . Platform 11 is, for example, a mother ship, a marine base, or the like. The underwater equipment 12 is, for example, an underwater vehicle, an underwater pipe, an observation equipment, and the like.

The water landing lifting system 13 includes a frame crane 21 supported on the platform 11, a pendant frame 22 suspended from the tip of the frame crane 21, and crawled along the frame crane 21 and the pendant frame 22 using a plurality of sheaves. A hoisting cable 24 and a hoist winch 25 for hoisting the hoisting cable 24 are provided. The tip of the hoisting cable 24 is coupled to a hoisting fitting 23 provided on the underwater equipment 12 . The frame crane 21 is elevated by hydraulic cylinders (not shown).

The hoist winch 25 includes a winch drum 27 around which the hoisting cable 24 is wound, and an electric motor 28 that rotates the winch drum 27 . The hoist winch 25 has a Heave Compensation function which will be described in detail later. Electric motor 28 is powered by power supply system 10 .

[Configuration of power supply system 10]
FIG. 2 is a block diagram showing the configuration of the power supply system 10. As shown in FIG. The power supply system 10 shown in FIG. 2 supplies power to an electric motor 28 serving as a power load L, and charges a power storage device 30 with regenerated electric power from the electric motor 28 . The power supply system 10 includes an engine 32 , an ECU 31 , a generator 35 , an electricity storage device 30 , a first inverter 29 , a second inverter 34 , a converter 33 and a control device 40 .

Engine 32 drives generator 35 . Electric power generated by the generator 35 is supplied to the power storage device 30 via the first inverter 29 and the converter 33 . Thereby, the power storage device 30 is charged. Also, the power generated by the generator 35 is supplied to the power load L via the first inverter 29 and the second inverter 34 . Power is supplied to the power load L from the power storage device 30 via the converter 33 and the second inverter 34 . Thereby, the electric storage device 30 is discharged.

The power storage device 30 is a DC power supply configured to be chargeable and dischargeable. A low-capacity, high-output power storage device is adopted as the power storage device 30 . A low-capacity electricity storage device can be defined as an electricity storage device with an electricity storage capacity of several Ah to several tens of Ah. A high-power electricity storage device can be defined as an electricity storage device that satisfies at least one of an output density of 3000 W/Kg or higher and a charge/discharge rate of 5 C or higher. Capacitors such as LIC and EDLC are exemplified as low-capacity, high-output power storage devices. In addition, a secondary battery such as a high-power lithium ion battery is exemplified as a low-capacity, high-power storage device.

The power storage device 30 includes a voltage sensor and a current sensor 41 (not shown). The voltage sensor detects the voltage of power storage device 30 and outputs it to control device 40 . Current sensor 41 detects an input/output current of power storage device 30 and outputs the detected current to control device 40 .

The engine 32 is, for example, an internal combustion engine such as a gasoline engine, a diesel engine, or a gas engine. The generator 35 uses the power of the engine 32 to generate electricity. The engine 32 is controlled by the ECU 31 so as to obtain an engine output corresponding to the generator output of the generator 35 (that is, the engine load). In addition, the generator 35 may be a motor generator. The motor-generator in this case is the generator 35 and the power load L as well.

The control device 40 controls the first inverter 29, the second inverter 34, and the converter 33 to supply power from the generator 35 to the power storage device 30 (that is, the amount of charge in the power storage device 30) and power from the power storage device 30. The electric power supplied to the load L (that is, the amount of discharge of the electric storage device 30) is controlled.

FIG. 3 is a functional block diagram of the control device 40. As shown in FIG. The control device 40 includes an arithmetic control section 51 and a storage section 52 . The arithmetic control unit 51 includes, for example, at least one of a microcontroller, a microprocessor, a PLD (programmable logic device) such as an FPGA (field-programmable gate array), a PLC (programmable logic controller), and a logic circuit, or It may consist of a combination of two or more. The storage unit 52 stores basic programs, software programs, and the like executed by the arithmetic control unit 51 .

The storage unit 52 stores an allowable lower limit value S1 and an allowable upper limit value S2 regarding the SOC average. Further, the storage unit 52 stores a reference value P1 and a correction value P2 relating to the generator output target value P. FIG. These values are values determined in advance by simulation or the like, and are stored in the storage unit 52 .

The calculation control unit 51 has functional units of an SOC calculation unit 51a, an SOC average calculation unit 51b, and a generator output determination unit 51c. In the control device 40, the functions of these functional units are realized by executing a pre-stored program in the arithmetic control unit 51. FIG. However, each functional unit of the arithmetic control unit 51 may be realized by logic circuits instead of programs.

The SOC calculation unit 51 a obtains the SOC of the power storage device 30 based on the detection value of the current sensor 41 and stores it in the storage unit 52 . The SOC is defined as the ratio of the remaining charge to the charge capacity of the power storage device 30 . The SOC is expressed using a method called “coulomb counting,” which integrates the current flowing into the storage device 30 and the current flowing out of the storage device 30 . However, the SOC calculation unit 51a may obtain the SOC of the electricity storage device 30 using the detection value of the voltage sensor.

The SOC average calculator 51b obtains an average value of SOC (hereinafter referred to as SOC average). Since the value of SOC constantly fluctuates, the SOC average is used as a representative value of SOC. The SOC average calculator 51b may be a moving average filter that obtains a moving average of the SOC for a predetermined period (for example, one cycle) as the SOC average. Alternatively, the SOC average calculator 51b may be a low-pass filter for SOC as the SOC average.

The generator output determination unit 51c determines the generator output target value P so that the SOC average falls within the allowable range from the allowable lower limit value S1 to the allowable upper limit value S2. The generator output target value P is determined from the reference value P1 and the correction value P2, which is a larger value than the reference value P1.

[Sway compensation function]
Here, the motion compensation function of the landing-on-water lifting-and-recovery system 13 will be described. The motion compensation function detects the motion of the platform 11 and adjusts the winch drum 27 so that the underwater equipment 12 connected to the hoisting cable 24 is shaken up and down due to the motion of the platform 11 . is rotated. Specifically, the electric motor 28 of the winch drum 27 constantly repeats the winding operation and the unwinding operation so that the tension of the hoisting cable 24 is kept substantially constant. During the winding operation, power is supplied from the generator 35 and/or the power storage device 30 to the electric motor 28 . During the feeding operation, electric power from the generator 35 and regenerated electric power from the electric motor 28 are stored in the power storage device 30 .

FIG. 4 is an example of a power load profile for one cycle (60 seconds). According to this power load profile, in this power load, regeneration and power running of ±8 MW (maximum power amount during regeneration: 5.8 MW, maximum power amount during power running: 7.4 MW) are repeated at intervals of about 10 seconds. . In power compensation for a power load that frequently repeats regeneration and power running (for example, oscillation compensation as in this embodiment), the storage device 30 frequently repeats charging and discharging. is preferred.

LIC is characterized by having a smaller power storage capacity than LIB. Therefore, the capacity of the LIC, which is determined assuming long-term operation, becomes significantly large. In order to verify this, a simulation was performed for each of LIC and LIB under the following conditions 1) to 4) to determine the specifications necessary for the storage device 30 to realize the power load profile shown in FIG. .
1) Maximum voltage about 1100V,
2) Environmental temperature of 25°C,
3) the rise (ΔT) of the saturation temperature of the cell is about 10° C. or less;
4) 24000 hours of operation time.
The condition that the rise (ΔT) of the saturation temperature of the cell is about 10° C. or less means that the power storage device can be used for 8 hours a day, 300 days a year, and 10 years as a vibration compensation function of the landing on water pick-up system 13. It is assumed from the possible temperature. However, one module of LIC is made up of 36 cells, and one module of LIB is made up of 24 cells, and the number of cells is increased for each module. In the power load profile of FIG. 4, the maximum power consumption during powering is 7.4011 MW, and in the case of LIB, the C rate (ratio of charging current value to storage capacity) in the first cycle is assumed to be 3C. The power storage device 30 requires a capacity of 2.467 MWh.

Table 1 below shows the specifications of the electric storage device 30 required to realize a one-cycle charge/discharge profile corresponding to the power load profile obtained in the above simulation. The specification items of the storage device 30 are the number of cells, maximum voltage, minimum voltage, initial SOC value, final SOC value, DOD, cell current effective value, and cell saturation temperature rise.

Furthermore, the number of cells of the electricity storage device 30 required to realize a charge-discharge profile from 1 to 10, 100, 200, 300, 400, 480 cycles (8 hours with 60 seconds per cycle), current effective value and C The rates are shown in Table 2 below.

From Tables 1 and 2, from the viewpoint of suppressing the number of cells, the LIC is advantageous because the number of cells required for the LIC is smaller than the number of cells required for the LIB in one cycle. However, in LIC, the number of required cells increases as the number of cycles increases, and the rate of increase is greater than that in LIB. LIC requires about nine times as many cells as one cycle in 1 to 480 cycles. One of the reasons for such a difference in change in the required number of cells is considered to be a difference in the amount of increase/decrease in SOC (hereinafter referred to as ΔSOC) in one cycle due to charge/discharge. ΔSOC is the difference between the SOC initial value and the SOC final value in one cycle.

The electromotive force of LIB exhibits a plateau characteristic in the SOC range of 10 to 90%. Therefore, in the LIB, the current value is substantially the same for a substantially constant charge/discharge capacity [W] in the SOC range of 10% to 90%, so ΔSOC does not depend on the SOC initial value. On the other hand, LIC has no electromotive force. Therefore, in the LIC, even if the charge/discharge capacity [W] is substantially constant, the current value varies depending on the SOC initial value, and ΔSOC also depends on the SOC initial value.

From the above, in order to realize the operation from 1 cycle to 480 cycles with the specifications of the electricity storage device 30 necessary to realize the charge/discharge profile of 1 cycle, the initial SOC value must be changed to 1 cycle each time the cycle is repeated. The SOC should be returned to the initial value. For that purpose, it is conceivable to compensate for the amount of stored electricity (corresponding to ΔSOC) lost in one cycle with electric power from the generator 35 .

Here, the flow of processing by the control device 40 for compensating for the amount of stored electricity lost in one cycle with the power from the generator 35 will be described. FIG. 5 is a flowchart showing the processing flow of the control device 40. As shown in FIG.

As shown in FIG. 5, control device 40 during vibration compensation acquires current values flowing in and out of power storage device 30, obtains the SOC of power storage device 30, and stores it (step S1). Next, the controller 40 obtains the SOC average of one cycle from the accumulated SOC (step S2). The controller 40 compares the calculated SOC average with the allowable upper limit value S2 (step S3), and if the SOC average exceeds the allowable upper limit value S2 (YES in step S3), the generator output target value P is used as a reference. The value is set to P1 (step S4). If the SOC average is equal to or lower than the allowable upper limit value S2 in step S3 (NO in step S3), the controller 40 compares the SOC average with the allowable lower limit value S1 (step S5). If the SOC average is below the allowable lower limit value S1 (YES in step S5), the control device 40 sets the output target value P to the correction value P2. If the SOC average is equal to or greater than the allowable lower limit value S1 in step S3 (NO in step S5), the control device 40 maintains the output target value P at the current value. The control logic for this power supply system 10 is displayed in Table 3 below.

The control device 40 determines the output target value P as described above, and outputs the generator output target value P to the generator 35 when there is a change in the output target value P (step S7). The output of the generator 35 is the load of the engine 32, and the output of the generator changes as the output of the engine 32 changes in response to this load. Therefore, the generator output target value P may be output to the ECU 31 . As a result, the generator output changes from the reference value P1 to the larger correction value P2. The power storage device 30 is charged with the increased power generated by the generator 35 (or supplied to the power load) to compensate for the amount of stored power lost in one cycle.

[Example 1]
In Example 1, the control method of the power supply system 10 described above will be described in detail by applying specific numerical values. In Example 1, the LIC is adopted as the electricity storage device 30, and the specification (4896 cells) of the electricity storage device 30 required to realize the charge/discharge profile corresponding to the power load profile of one cycle (see FIG. 4) is , to achieve operation from 1 cycle to 480 cycles (8 hours). The charging/discharging SOC (amount of stored electricity) characteristics of the electricity storage device 30 in one cycle adopted in this embodiment are as shown in Table 4 below.

From various SOC values for one cycle, a reference value P1 and a correction value P2 for the generator output target value P for compensating for the amount of electricity stored in the generator to be lost in one cycle are obtained. In this embodiment, a target generator load value for increasing the average SOC from 62.592% by 12.555% corresponding to ΔSOC is obtained.

In the following Table 5, one cell of LIC is given an initial SOC value, and a simulation is performed in which 25 W charging is performed at various values of SOC in one cycle. indicate a value.

From Table 5, it can be seen that when the initial SOC value is 60%, charging 25 W per cell for 60 seconds (one cycle) increases the SOC by 12.5% corresponding to ΔSOC. A negative value of ΔSOC indicates an increase in SOC. Therefore, the correction value P2 of the generator output target value P for increasing the SOC from 62.592% (≈60%) by 12.555% (≈12.5%) is 25W×4896 cells≈125kW. can be estimated as

Considering the SOC initial value and the SOC maximum value, a value smaller than the correction value P2 is determined as the basic value P1 of the generator output target value P so that the power storage device 30 is not overcharged by the generator output. In this embodiment, the basic value P1 is set to 115 kW, which is less than the charging power amount obtained by the correction value P2 by about 2 W per cell.

The generator output target value P is switched from the basic value P1 to the correction value P2, triggered by the SOC average falling below the allowable lower limit value S1. The difference between the SOC maximum value and the SOC average is taken as the average price range. In this embodiment, the average price range is 22.497%. In order to avoid overcharging of the electric storage device 30, the allowable upper limit value S2 of the SOC average is set to 70% in consideration of the SOC average and the average price range.

The allowable lower limit value S1 corresponding to the allowable upper limit value S2 of the SOC average is determined, and the allowable range of the SOC average (not less than the allowable lower limit value S1 and not more than the allowable upper limit value S2) is set. As shown in Table 4, the current values are different even if the charge/discharge amount is the same. From the viewpoint of suppressing fluctuations in the current effective value, it is desirable that the allowable range of the SOC average is 5 to 10%. In this embodiment, since the allowable upper limit value S2 of the SOC average is 70%, the allowable lower limit value S1 is set to 65%.

When the control logic of the power supply system 10 is applied to the present embodiment, the generator output target value P is switched to 115 kW when the SOC average >70%, and the generator output target value P is switched to 125 kW when the SOC average <65%. %≦SOC average≦70%, the current generator output target value P is maintained. Using this control logic, a simulation of fluctuation compensation in which load fluctuations of the power load L (the power load profile shown in FIG. 4) are compensated by the power storage device 30 was performed. FIG. 6 is a time chart showing the simulation results of vibration compensation for the first hour, and FIG. 7 is a time chart showing the simulation results of vibration compensation for the first eight hours. 6 and 7, the vertical axis represents the SOC, SOC average, and generator output target value P, and the horizontal axis represents time. Furthermore, Table 6 below shows the values relating to the charge/discharge characteristics of the electrical storage device 30 obtained from the results of the vibration compensation simulation.

In the simulation results shown in FIGS. 6 and 7, the generator output target value P is switched from the basic value P1 to the correction value P2 (or vice versa) at intervals of 800 to 900 seconds. When changing the generator output target value P, it may be changed stepwise or may be changed with a time gradient. Since the change in the generator output target value P has a time gradient, rapid load fluctuations of the generator 35 and the engine 32 can be suppressed.

According to the simulation results, by switching the generator output target value P between the basic value P1 and the correction value P2 based on the SOC value, even after 8 hours of operation, the same level as during the first hour of operation SOC is maintained. Furthermore, as shown in Table 6, stable and ideal charge/discharge characteristics were obtained during operation for 8 hours. From the above examples, it was confirmed that 8 hours of operation is possible with the specifications of the electricity storage device 30 that realizes a power load profile of one cycle.

Further, from the simulation results, when supplying the necessary and sufficient power to the power load L corresponding to the power load profile (see FIG. 4) in which power running and regeneration are repeated at ±8 MW, power is supplied only by the generator 35. In this case, a generator 35 that generates power of 8 MW or more is required, but it is clear that the power generator 35 that generates power of about 150 kW is sufficient by providing the power storage device 30 as in this embodiment. became. In other words, with respect to the load fluctuation of ±several MW of the power load L, the power storage device 30 can be repeatedly charged and discharged while avoiding over-discharging and over-charging with the power generator 35 having a scale of several 100 kW. Since the size of the generator 35 included in the power supply system 10 can be reduced in this way, reductions in initial cost and fuel consumption for the generator 35 can be expected.

As described above, the power supply system 10 according to the present embodiment includes the engine 32, the power generator 35 that generates power using the power of the engine 32, the power generated by the power generator 35, and the power load L A power storage device 30 that stores at least one of regenerated power, a power supply unit (second inverter 34) for supplying the power stored in the power storage device and the power generated by the generator to the power load L, and a control a device 40; The control device 40 measures the SOC of the electricity storage device 30, obtains the SOC average value from the measured SOC, determines the generator output target value P based on the SOC average value, and sets the output of the generator to the generator output target value. P is configured to be controlled. Here, the generator output target value P is determined as a predetermined basic value P1 larger than 0 if the SOC average value exceeds a predetermined allowable upper limit value S2, and if the SOC average value falls below a predetermined allowable lower limit value S1 A correction value P2 larger than the basic value P1 is determined, and if the SOC average value is equal to or greater than the allowable lower limit value S1 and equal to or lower than the allowable upper limit value S2, it is decided to maintain the current generator output target value P.

Further, the control method of the power supply system 10 configured as described above includes measuring the SOC of the power storage device 30, obtaining the SOC average value from the measured SOC, and determining the generator output target value P based on the SOC average value. and controlling the output of the generator 35 corresponding to the generator output target value P. Here, the generator output target value P is determined as a predetermined basic value P1 larger than 0 if the SOC average value exceeds a predetermined allowable upper limit value S2, and if the SOC average value falls below a predetermined allowable lower limit value S1 A correction value P2 larger than the basic value P1 is determined, and if the SOC average value is equal to or greater than the allowable lower limit value S1 and equal to or lower than the allowable upper limit value S2, it is decided to maintain the current generator output target value P.

According to the power supply system 10 and its control method described above, if the SOC average value decreases, power is supplied from the generator 35 to the power storage device 30 so as to compensate for the lost power storage amount. As a result, regardless of the number of charge/discharge cycles, the SOC average value is maintained within the permissible range between the permissible lower limit value S1 and the permissible upper limit value S2. The simple control of changing the generator output between the two values of the reference value P1 and the correction value P2 can suppress the influence of charge-discharge efficiency caused by repeated charge-discharge. As a result, the power storage device can repeat charging and discharging while avoiding over-discharging and over-charging. Since the power storage device 30 generally maintains the charge amount at the initial stage of operation, it is sufficient to have a capacity and output that satisfy the charge/discharge profile (that is, the required charge/discharge amount) at the beginning of operation. The number of cells (system size, capacity) of 30 can be suppressed.

In a conventional hybrid system, first, the engine output is determined, and then the capacity and output of the electrical storage device are determined so that the engine output can be assisted by the electrical storage device. That is, the main manipulated variable is the engine output, and the auxiliary manipulated variable is the output of the power generation device. The engine output corresponds to the generator output. On the other hand, in the power supply system 10 according to the present embodiment, the main operation amount is the output of the power storage device 30, the system size of the power storage device 30 that satisfies the power load profile at the beginning of operation is determined, and with that system size The generator output is controlled to achieve long-time operation. Such a change in thinking can reduce the system size of the electricity storage device 30 .

Also, in this embodiment, the power generated by the generator 35 is mainly used to compensate for the charge/discharge efficiency of the electricity storage device 30 . That is, compared to the case where the load fluctuation of the power load is suppressed only by the power generated by the power generator 35, the physical size (size) of the power generator 35 included in the power supply system 10 can be suppressed. In this way, the size of the power storage device 30 is suppressed and the size of the generator 35 can be reduced, thereby reducing the space occupied by the power storage device 30 and the power generator 35, the initial cost, and the running cost. It becomes possible to

In the power supply system 10 and its control method described above, the power storage device 30 may be one or a combination of two or more of lithium ion capacitors, electric double layer capacitors, and high-power lithium ion batteries. The control logic according to the present embodiment is suitable for such a low-capacity, high-output power storage device 30 capable of rapid charging and discharging and having a relatively small capacity.

In the power supply system 10 and its control method described above, the SOC average value may be a moving average value of SOC or a low-pass filter output value. Since the SOC constantly fluctuates, it is desirable to employ such an SOC average value.

Although the preferred embodiments of the present invention have been described above, the present invention may include modifications of the details of the specific structures and/or functions of the above embodiments without departing from the spirit of the present invention. .

10: Power supply system 11: Platform 12: Underwater equipment 13: Landing on water lifting system 21: Frame crane 22: Pendant frame 23: Lifting hardware 24: Lifting rope 25: Hoist winch 27: Winch drum 28: Electric motor (electric power Example of load)
29: first inverter 30: power storage device 31: ECU
32: Engine 33: Converter 34: Second inverter (an example of a power supply unit)
35: Generator 40: Control device 41: Current sensor 51: Calculation control unit 51a: SOC calculation unit 51b: SOC average calculation unit 51c: Generator output determination unit 52: Storage unit 80: Fourth
L : Power load

Claims (7)

an engine, a generator that generates power using the motive power of the engine, a power storage device that stores at least one of the power generated by the power generator and regenerated power from the power load, and the power stored in the power storage device and A control device for a power supply system comprising a power supply unit for supplying power generated by the generator to a power load,
The SOC of the electricity storage device is measured, the SOC average value is obtained from the SOC, the generator output target value is determined based on the SOC average value, and the output of the generator is set to the generator output target value. configured to control
The generator output target value is determined to be a predetermined basic value greater than 0 if the SOC average value exceeds a predetermined allowable upper limit value, and if the SOC average value is lower than a predetermined allowable lower limit value, the generator output target value is determined to be higher than the basic value. is determined to be a large correction value, and if the SOC average value is equal to or greater than the allowable lower limit value and equal to or lower than the allowable upper limit value , the current generator output target value is determined, and the generator output target value is set to the basic value and the Change between two values with the correction value ,
Control device for the power supply system. The SOC average value is a moving average value or a low-pass filter output value of the SOC,
The power supply system control device according to claim 1 . engine and
a generator that generates power using the power of the engine;
a power storage device that stores at least one of the power generated by the generator and the regenerated power from the power load;
a power supply unit for supplying at least one of the power stored in the power storage device and the power generated by the generator to a power load;
A control device according to claim 1 or 2,
power supply system. The electricity storage device is any one or a combination of two or more of a lithium ion capacitor, an electric double layer capacitor, and a high power lithium ion battery,
The power supply system according to claim 3. an engine, a generator that generates power using the motive power of the engine, a power storage device that stores at least one of the power generated by the power generator and regenerated power from the power load, and the power stored in the power storage device and A control method for a power supply system comprising a power supply unit for supplying power generated by the generator to a power load,
measuring the SOC of the electricity storage device;
obtaining an SOC average value from the SOC;
determining a generator output target value based on the SOC average value; and
controlling the output of the generator in response to the generator output target value;
The generator output target value is determined to be a predetermined basic value greater than 0 if the SOC average value exceeds a predetermined allowable upper limit value, and if the SOC average value is lower than a predetermined allowable lower limit value, the generator output target value is determined to be higher than the basic value. is determined to be a large correction value, and if the SOC average value is equal to or greater than the allowable lower limit value and equal to or lower than the allowable upper limit value , the current generator output target value is determined, and the generator output target value is set to the basic value and the Change between two values with the correction value ,
A method of controlling a power supply system. The electricity storage device is any one or a combination of two or more of a lithium ion capacitor, an electric double layer capacitor, and a high power lithium ion battery,
The control method of the power supply system according to claim 5. The SOC average value is a moving average value or a low-pass filter output value of the SOC,
A control method for a power supply system according to claim 5 or 6.

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