Power generation control device, power generation control method, power generation control program

Abstract

To provide a power generation control device that can reduce a fuel consumption during power generation.SOLUTION: A power generation control device 6 includes: a calculation unit 61 that calculates a fuel consumption per unit generation energy of a diesel generator 4 having an engine unit 41 that outputs rotational power by means of combustion of an input fuel and a power generation unit 42 that converts the rotational power into power; a changing unit 62 that changes operation conditions of the diesel generator 4 so as to change output of the diesel generator 4; a specifying unit 63 that compares the fuel consumption per unit generation energy calculated by the calculation unit 61 under the operation conditions before being changed and a fuel consumption per unit generation energy calculated by the calculation unit 61 under operation conditions after being changed, and specifying the operation conditions of a smaller one of the fuel consumptions; and a power generation control unit 64 that operates the diesel generator 4 under the specified operation conditions.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to power generation control technology.

Background Art

[0002] Patent Document 1 discloses a power generation control device for a ship that restricts the output of a diesel generator within a range of a predetermined ratio of the on-board load. Specifically, by restricting the output of the diesel generator to 60% or more and 90% or less of the on-board load, which is said to have good fuel efficiency of the diesel generator, that is, low fuel consumption per unit generated energy of the diesel generator, high fuel efficiency can be achieved.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, a fixed output range of 60% or more and 90% or less of the on-board load was set. However, it is assumed that the fuel efficiency of the diesel generator may vary depending on the diesel generator itself and the situation where the ship is placed, and the above output range does not always achieve high fuel efficiency. Further, since it is assumed that there is a portion with relatively low fuel efficiency even within the above output range, there is a risk of causing wasteful fuel consumption.

[0005] The present invention has been made in view of such a situation, and an object thereof is to provide a power generation control device capable of reducing the fuel consumption during power generation.

Means for Solving the Problems

[0006] In order to solve the above problems, a power generation control device according to an aspect of the present invention includes a calculation unit that calculates the fuel consumption per unit generated energy of a generator having an engine unit that outputs rotational power by burning the input fuel and a power generation unit that converts the rotational power into electric power, a change unit that changes the operating conditions of the generator so as to change the output of the generator, a comparison between the fuel consumption per unit generated energy calculated by the calculation unit under the operating conditions before the change and the fuel consumption per unit generated energy calculated by the calculation unit under the operating conditions after the change, a specifying unit that specifies the operating conditions with less fuel consumption, and a power generation control unit that operates the generator under the specified operating conditions.

[0007] In this aspect, since the change unit changes the operating conditions of the generator, the specifying unit specifies the operating conditions with less fuel consumption per unit generated energy, and the power generation control unit operates the generator under the operating conditions, the fuel consumption during power generation can be reduced.

[0008] Another aspect of the present invention is a power generation control method. This method includes a calculation step of calculating the fuel consumption per unit generated energy of a generator having an engine unit that outputs rotational power by burning the input fuel and a power generation unit that converts the rotational power into electric power, a change step of changing the operating conditions of the generator so as to change the output of the generator, a specifying step of comparing the fuel consumption per unit generated energy calculated in the calculation step under the operating conditions before the change and the fuel consumption per unit generated energy calculated in the calculation step under the operating conditions after the change, and specifying the operating conditions with less fuel consumption, and a power generation control step of operating the generator under the specified operating conditions.

[0009] Note that any combination of the above components, as well as those obtained by converting the expression of the present invention among a method, an apparatus, a system, a recording medium, a computer program, etc., are also effective as aspects of the present invention.

Effects of the Invention

[0010] According to the present invention, the fuel consumption during power generation can be reduced.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0012] FIG. 1 is a functional block diagram showing the configuration of a ship power supply system 1. The power supply system 1 is a system that supplies AC power to an in-ship load 3 via a power bus 2, and includes a diesel generator 4 as a generator that generates AC power, a battery 5 that can be charged and discharged with the power bus 2 via an AC / DC conversion unit 51, and a power generation control device 6 that controls the power generation of the diesel generator 4 and the charge / discharge of the battery 5.

[0013] The diesel generator 4 includes an engine unit 41 that outputs rotational power by burning the supplied fuel, and a power generation unit 42 that converts the rotational power of the engine unit 41 into electric power. The engine unit 41 in the diesel generator 4 is composed of a diesel engine, but the engine unit of the generator in the present invention may be composed of other types of engines. The power generation unit 42 generates AC power from the rotational power of the engine unit 41 and supplies it to the power bus 2.

[0014] A battery 5 is connected to a power bus 2 for supplying AC power to an in-ship load 3 via an AC / DC conversion unit 51 as a power conversion unit that mutually converts AC power and DC power. When the battery 5 is being charged, the AC power on the power bus 2 generated by the diesel generator 4 is converted into DC power by the AC / DC conversion unit 51 to charge the battery 5. When the battery 5 is discharging, the DC power from the battery 5 is converted into AC power by the AC / DC conversion unit 51 and supplied to the power bus 2. The charge / discharge control of the battery 5, that is, the power conversion control of the AC / DC conversion unit 51, is performed by a power generation control device 6.

[0015] The SOC (State Of Charge) of the battery 5 that is charged and discharged as described above is monitored by the power generation control device 6, and control is performed so that the battery 5 does not perform excessive charging / discharging.

[0016] The in-ship load 3 to which AC power is supplied from the power bus 2 may include lighting for in-ship living facilities, an air conditioning system, and a motor that rotationally drives a propeller that generates propulsion power in a hybrid ship or an electric ship. The hybrid ship may be of a series type in which an engine unit 41, a power generation unit 42 (including the battery 5), a motor, and a propeller are connected in series, or may be of a parallel type in which the engine unit 41 can directly rotationally drive the propeller and a motor that can rotationally drive the propeller with the power generated by the power generation unit 42 based on the rotational power of the engine unit 41 is provided in parallel.

[0017] The power generation control device 6 includes a calculation unit 61, a modification unit 62, a specification unit 63, a power generation control unit 64, a loss acquisition unit 65, a power measurement unit 66, and a power comparison unit 67. These functional blocks are realized by the cooperation of hardware resources such as a central processing unit of a computer, a memory, an input device, an output device, and peripheral devices connected to the computer, and software executed using them. Regardless of the type and installation location of the computer, each of the above functional blocks may be realized by the hardware resources of a single computer, or may be realized by combining the hardware resources distributed among a plurality of computers. In particular, in the present embodiment, some or all of the functional blocks of the power generation control device 6 may be realized by a computer on board the ship, or may be realized by a computer outside the ship that can communicate with the computer on board the ship.

[0018] The calculation unit 61 calculates the fuel consumption per unit generated energy of the diesel generator 4. The fuel consumption F [g / kWh] per unit generated energy, also called fuel consumption rate or fuel efficiency, can be expressed as F = W / E, where W [g] is the measured fuel consumption of the diesel generator 4 and E [kWh] is the measured generated energy. The lower the fuel consumption F per unit generated energy, the better the fuel consumption rate or fuel efficiency, and the higher the fuel consumption F per unit generated energy, the worse the fuel consumption rate or fuel efficiency.

[0019] The change unit 62 changes the operating conditions of the diesel generator 4 so as to change the output of the diesel generator 4. Here, the output P [kW] of the diesel generator 4 is determined by the torque T [Nm] and the rotation speed N [rpm] of the engine unit 41, and is expressed as P = 2πTN / 60 / 1000. In this way, the set (T, N) of the torque T and the rotation speed N of the engine unit 41 determines the operating conditions of the diesel generator 4, and when the change unit 62 changes at least one of the operating conditions, i.e., the torque T and the rotation speed N, the output P of the diesel generator 4 changes according to the above formula. Note that since the onboard loads 3 to which AC power is supplied from the power bus 2 are often capable of operating only with AC power of a constant frequency (e.g., 60 Hz), it is preferable to keep the rotation speed N of the engine unit 41 constant so that the power generation unit 42 generates AC power of a constant frequency that meets the requirements of the onboard loads 3. In this case, since the rotation speed N of the engine unit 41 is kept constant, the output P of the diesel generator 4 changes with the change in the torque T of the engine unit 41. Hereinafter, the output P [kW] of the diesel generator 4 is the rated output or maximum output P max Ratio P / P to [kW] max It is sometimes expressed as [%].

[0020] The determination unit 63 determines the fuel consumption F per unit generated energy calculated by the calculation unit 61 under the operating conditions before the change by the change unit 62. before and the fuel consumption amount F per unit of generated energy calculated by the calculation unit 61 under the changed operating conditions. after and identify the operating condition with the lesser fuel consumption. The power generation control unit 64 operates the diesel generator 4 under the operating condition with the lesser fuel consumption identified by the identifying unit 63. In this manner, in this embodiment, the changing unit 62 changes the operating condition of the diesel generator 4, the identifying unit 63 identifies the operating condition with the lesser fuel consumption amount F per unit generated energy, and the power generation control unit 64 operates the diesel generator 4 under that operating condition, so that the amount of fuel consumed during power generation can be reduced.

[0021] FIG. 2 shows an example of the relationship between the fuel consumption [g / kWh] (fuel consumption per unit generated energy) and the output [%] in the diesel generator 4. As shown in FIG. 2(A), in the low-output region where the output P of the diesel generator 4 is lower than about 60% of the rated output P max , it can be seen that the fuel consumption per unit generated energy is high and the fuel efficiency is poor. In the high-output region where the output P of the diesel generator 4 is higher than about 60% of the rated output P max , high fuel efficiency is achieved. However, as shown in FIG. 2(B) which is an enlarged view thereof, even within the high-output region, there is an optimal output (85% in the illustrated example) at which the fuel consumption is minimized (F min ). In the present embodiment, the object is to efficiently identify such an optimal output (85%) and operate the diesel generator 4 at the minimum fuel consumption (F min ).

[0022] FIG. 3 schematically shows an example of a method for identifying the optimal output by the power generation control device 6. In this example, the changing unit 62 gradually changes the operating conditions of the diesel generator 4 (particularly the torque T of the engine unit 41) for each of a plurality of periods (A) to (E) to change the output. The calculating unit 61 calculates the fuel consumption (fuel consumption per unit generated energy) at each operating condition sequentially changed by the changing unit 62. In the first period (A), assuming that as a result of the changing unit 62 changing to the first operating condition, the diesel generator 4 shows the first output P1 and the calculating unit 61 calculates the first fuel consumption F1. In the subsequent second period (B), assuming that as a result of the changing unit 62 changing from the first operating condition to the second operating condition, the diesel generator 4 shows a second output P2 larger than the first output P1 and the calculating unit 61 calculates a second fuel consumption F2 smaller than the first fuel consumption F1.

[0023] As the output of the diesel generator 4 increases from P1 to P2 along with the transition from the first period (A) to the second period (B), the surplus power due to the output increase is charged to the battery 5 by increasing the current command or the charging command from the power generation control unit 64 to the AC / DC conversion unit 51. Since the surplus power is thus charged to the battery 5 and not supplied to the in-ship load 3, the power supplied to the in-ship load 3 is kept substantially constant through the process of FIG. 3. As a result, the change in the state of the in-ship load 3 is minimized, and thus the power generation control device 6 can accurately find the optimal output (85%) that realizes the minimum fuel consumption (F min ) of the diesel generator 4 without being greatly affected by the in-ship load 3. Note that as a result of the increase in the current command or the charging command in the second period (B), the increase rate (the slope of the straight line) of the SOC (State Of Charge) of the battery 5 is larger than that in the first period (A). Also, as described above, in order to keep the frequency of the AC power generated by the diesel generator 4 constant (60 Hz), the rotational speed N of the engine unit 41 is kept constant. In this case, the change in the output of the diesel generator 4 in FIG. 3 is mainly caused by the change in the torque T (operating condition) of the engine unit 41.

[0024] As a result of the change unit 62 increasing the output of the diesel generator 4 in the second period (B), the fuel consumption calculated by the calculation unit 61 decreased (the fuel efficiency improved). Therefore, in the subsequent third period (C), the change unit 62 further increases the output of the diesel generator 4 in anticipation of further improvement in fuel efficiency. Specifically, in the third period (C), as a result of the change unit 62 changing from the second operating condition to the third operating condition, the diesel generator 4 shows a third output P3 that is larger than the second output P2, and it is assumed that the calculation unit 61 calculates a third fuel consumption F3 that is less than the second fuel consumption F2. At this time, similar to the second period (B), as the output increases from P2 to P3, the current command or the charging command from the power generation control unit 64 to the AC / DC conversion unit 51 increases, and a larger surplus power is charged to the battery 5. For this reason, the increase rate of the SOC of the battery 5 also becomes larger than that in the second period (B).

[0025] As a result of the modification unit 62 increasing the output of the diesel generator 4 during the third period (C), the fuel consumption calculated by the calculation unit 61 decreased (fuel efficiency improved). Therefore, in the subsequent fourth period (D), the modification unit 62 further increased the output of the diesel generator 4 in anticipation of further improvement in fuel efficiency. Specifically, in the fourth period (D), as a result of the modification unit 62 changing from the third operating condition to the fourth operating condition, the diesel generator 4 exhibits a fourth output P4 that is greater than the third output P3. However, unlike the second period (B) and the third period (C), it is assumed that the calculation unit 61 calculated a fourth fuel consumption F4 that is greater than the third fuel consumption F3 (combustion efficiency is poor).

[0026] Through the above process, the specifying unit 63 recognizes that even if the output of the diesel generator 4 is increased beyond the third output P3, the fuel efficiency will not improve any further. Therefore, the specifying unit 63 specifies the third operating condition during the third period (C) in which the minimum fuel consumption F3 was obtained as the operating condition to be adopted in the immediate future operation of the diesel generator 4. The power generation control unit 64 operates the diesel generator 4 at the optimum output (85%) that realizes the minimum fuel consumption (F min ) during the operating periods after the fifth period (E).

[0027] In the above example, the optimal output of the diesel generator 4 was a constant value (85%), but it is also assumed that it may change depending on the diesel generator 4 itself and the situation where the ship is located. Specifically, the optimal output of the diesel generator 4 may vary depending on the temperature of the engine unit 41, the type and state of the fuel in the engine unit 41, the state of the nozzle for injecting fuel in the engine unit 41, and the like. According to the process shown in FIG. 3, even when the optimal output of the diesel generator 4 changes, the optimal output that realizes the minimum fuel consumption can be efficiently specified. Further, in the above example, as schematically shown in FIG. 2(B) as well, while gradually increasing the output of the diesel generator 4 over the period (A) to (D), the optimal output in the period (C) where the minimum fuel consumption is achieved was searched for. Conversely, the optimal output that achieves the minimum fuel consumption may be searched for while gradually decreasing the output of the diesel generator 4 from around 90% to 95%. When the search is performed while decreasing the output of the diesel generator 4, it is also assumed that the insufficient power to the in-ship load 3 is covered by the power stored in the battery 5. For this reason, it is preferable that the change in the operating conditions or output by the changing unit 62 is performed only when the SOC indicating the charge amount of the battery 5 is equal to or higher than a predetermined value, that is, when there is a discharge margin. Conversely, when the search is performed while increasing the output of the diesel generator 4, since the surplus power is charged to the battery 5, it is preferable that the change in the operating conditions or output by the changing unit 62 is performed only when the SOC indicating the charge amount of the battery 5 is equal to or lower than a predetermined value, that is, when there is a charge margin.

[0028] The search process for the optimal output involving the change of operating conditions by the change part 62 as shown in Fig. 3 does not need to be executed constantly, and it is preferably performed when the operating conditions such as the diesel generator 4 and the situation where the ship is placed change significantly. For example, when the ship is refueled, due to the difference between the existing fuel and the refueled fuel, the optimal output for the minimum fuel consumption may change significantly, so the search process for the optimal output involving the change of operating conditions by the change part 62 is executed. Also, the change part 62 may change the operating conditions of the diesel generator 4 according to the change in the current position of the ship. For example, when the ship enters or exits a port, coastal waters, the open ocean, etc., the operating conditions of the diesel generator 4 may change significantly, so the search process for the optimal output involving the change of operating conditions by the change part 62 is executed. Also, when a plurality of diesel generators 4 are provided on the ship and are used by being sequentially switched, since the optimal output for the minimum fuel consumption may be different for each diesel generator 4, the search process for the optimal output involving the change of operating conditions by the change part 62 is executed for the diesel generator 4 after the switching. Note that the search process for the optimal output may be periodically executed at regular intervals.

[0029] Note that when executing the search process for the optimal output involving the change of operating conditions by the change part 62 as shown in Fig. 3, the amount of change in the operating conditions of the diesel generator 4 for each period, that is, the change amount of at least either the rotation speed N or the torque T of the engine part 41, is preferably determined according to at least either the temperature of the engine part 41, the type of fuel input to the engine part 41, or the state of the nozzle for injecting fuel in the engine part 41. For example, when the engine part 41 is hotter than normal, even a slight difference in operating conditions may cause a significant change in fuel consumption, so it is preferable to reduce the amount of change in the operating conditions for each period by the change part 62.

[0030] FIG. 4 is a flowchart showing the process of specifying the optimal output by the power generation control device 6. In the description of the flowchart, "S" means step. In S20 to S22, it is determined whether to execute the search process for the optimal output. In S20, it is determined whether fuel has been replenished to the ship. In S21, it is determined whether the current position of the ship has changed significantly. In S22, it is determined whether the diesel generator 4 has been switched. If it is determined Yes in any of these steps, the process proceeds to S23, and the search process for the optimal output in S24 to S31 involving the change of the operating conditions by the changing unit 62 is executed. If it is determined No in all of these steps, the process ends without executing the search process for the optimal output. Note that steps S20 to S22 may not be provided, or any one of them may be provided, or any number of them may be combined.

[0031] In S24, the changing unit 62 sets the operating conditions of the diesel generator 4 to the first operating conditions. In S25, the calculating unit 61 calculates the first fuel consumption F1 under the first operating conditions. In S26, the changing unit 62 sets the operating conditions of the diesel generator 4 to the second operating conditions (N is a natural number of 2 or more). Here, it is assumed that the operating conditions are changed by the changing unit 62 so that the output of the diesel generator 4 increases as in the example of FIG. 3. In S27, the calculating unit 61 calculates the second fuel consumption F2 under the second operating conditions. In S28, the first fuel consumption F1 and the second fuel consumption F2 are compared. If the second fuel consumption F2 is less than the first fuel consumption F1 as in the example of FIG. 3, the process proceeds to S29, where the natural number N is incremented and then the process returns to S26.

[0032] Thereafter, until the (N - 1)th fuel consumption F N-1 is less than or equal to the Nth fuel consumption F N the processes in S26 to S29 are repeated. In the example of FIG. 3, when N = 4, the third fuel consumption F3 is less than or equal to the fourth fuel consumption F4 in S28. Therefore, in the subsequent S30, the specifying unit 63 specifies the third (N - 1)th operating conditions under which the minimum fuel consumption F3 is obtained as the operating conditions to be adopted in the immediate future operation of the diesel generator 4. In S31, the power generation control unit 64 operates the diesel generator 4 under the operating conditions specified in S30.

[0033] In addition, in the process of searching for the optimal output in FIG. 3 or FIG. 4, the output of the diesel generator 4 was gradually increased (or decreased), and the optimal output at which the fuel consumption immediately before the fuel consumption starts to increase becomes minimal was searched for. However, the output of the diesel generator 4 may be changed regularly or irregularly a predetermined number of times (for example, 10 times), and the output of the diesel generator 4 when the fuel consumption becomes the lowest among them may be specified as the optimal output.

[0034] The loss acquisition unit 65 acquires the losses during charging and discharging in the rechargeable battery 5 for the surplus power exceeding the required power of the in-ship load 3 among the power generated by the diesel generator 4. The loss acquisition unit 65 may acquire the losses during charging and discharging of the battery 5 according to the output and fuel consumption of the diesel generator 4 from a previously prepared table as shown in FIG. 5 described later, or may calculate the losses during charging and discharging of the battery 5 based on the current command from the power generation control unit 64 to the AC / DC conversion unit 51 and the charge rate (SOC) of the battery 5. In the latter case, since the current command from the power generation control unit 64 to the AC / DC conversion unit 51 represents the current to be passed during charging and discharging of the battery 5, and the charge rate of the battery 5 represents the current actually flowing through the battery 5, the current loss in the battery 5 can be calculated by comparing these. In addition, the loss acquisition unit 65 may calculate the losses during charging and discharging of the battery 5 based on the comparison of the AC power on the power bus 2 side of the AC / DC conversion unit 51 and the DC power on the battery 5 side measured by the power measurement unit 66. The power comparison unit 67 compares the power generation amount of the diesel generator 4, the charge amount of the battery 5, and the required power of the in-ship load 3 in the power generation control process shown in FIG. 6 described later.

[0035] Before explaining the power generation control process of FIG. 6, the table of FIG. 5 will be explained. "Output (in-ship load)" is the rated output P maxshows the output of the diesel generator 4 with a capacity of 1000 kW in both [%] and [kW] units. For example, an output of 85% represents an output of 850 kW. The "fuel consumption" [g / kWh] indicates the fuel consumption per unit of generated energy of the diesel generator 4 calculated by the calculation unit 61. Similar to the examples in FIGS. 2 and 3, the fuel consumption is minimized when the output is 85%. That is, also in this example, the optimal output of the diesel generator 4 that achieves the minimum fuel consumption (198.40 g / kWh) is 85%. The "fuel usage" [g / s] is obtained by converting the fuel consumption into the fuel usage per unit time.

[0036] The "fuel usage when operating at 85% output" [g / s] indicates the fuel usage when the diesel generator 4 is operated at the optimal output of 85% with respect to the in-ship load 3 for each value in the "output (in-ship load)". For example, the fuel usage when the diesel generator 4 is operated at the optimal output of 85% with respect to the in-ship load 3 of 85% (850 kW) is the same as 46.84 in the left column. On the other hand, the fuel usage when the diesel generator 4 is operated at the optimal output of 85% with respect to the in-ship load 3 of 10% (100 kW) is 5.51, which is less than 15.09 in the left column. 15.09 in the left column is the fuel usage when the diesel generator 4 is operated at an output of 10% equal to the in-ship load 3 of 10% (100 kW), but since the fuel consumption is 543.30, which is worse than the minimum fuel consumption of 198.40, it is more than 5.51 when the diesel generator 4 is operated at the minimum fuel consumption. Thus, even if the in-ship load 3 (e.g., 10%) is different from the optimal output (85%) of the diesel generator 4, operating the diesel generator 4 at the optimal output may reduce the fuel usage.

[0037] Such a reduction in fuel consumption is indicated as "(A) Fuel consumption improvement" [g / s]. When the in-ship load 3 is 10%, the difference between 15.09 at 10% output and 5.51 at 85% output, which is 9.58, becomes the fuel consumption improvement. On the other hand, when the diesel generator 4 is operated at the optimal output of 85% with respect to the in-ship load 3 of 10%, 75% of the difference becomes surplus power and is charged to the battery 5 via the AC / DC conversion unit 51. What is obtained by converting the loss generated in the battery 5 during the charging of this surplus power (which can be obtained by the loss acquisition unit 65) into fuel consumption is indicated as "(B) Fuel consumption of loss" [g / s]. In this figure, the loss during charging and discharging of the battery 5 is assumed to be 15%.

[0038] When the in-ship load 3 is 10%, the fuel consumption of loss is 6.20, which is lower than the fuel consumption improvement of 9.58 in the left column. Therefore, when the in-ship load 3 is 10%, the fuel consumption or fuel efficiency can be minimized by operating the diesel generator 4 at the optimal output of 85%. On the other hand, when the in-ship load 3 is 50 - 80%, "(B) Fuel consumption of loss" exceeds "(A) Fuel consumption improvement". For this reason, even if the diesel generator 4 is operated at the optimal output of 85%, the fuel efficiency deteriorates due to the loss of the battery 5 during charging. In such a case, the diesel generator 4 can minimize the fuel consumption or fuel efficiency by operating at an output equal to the in-ship load 3 (50 - 80%) instead of the optimal output of 85%.

[0039] Figure 6 is a flowchart showing the power generation control process by the power generation control device 6. In the description of the flowchart, "S" means step. In S1, the power comparison unit 67 compares the SOC (charge rate) of the battery 5 with the full charge determination threshold A. The full charge determination threshold A is a threshold for determining whether the battery 5 is in a charging state close to full charge. When the SOC of the battery 5 is greater than the full charge determination threshold A (No in S1), it is assumed that the battery 5 is in a full charge state and the process proceeds to S13. When the SOC of the battery 5 is less than or equal to the full charge determination threshold A (Yes in S1), it is assumed that the battery 5 is not in a full charge state and the process proceeds to S2.

[0040] In S2, the power comparison unit 67 compares the SOC of the battery 5 with the full-discharge determination threshold B. The full-discharge determination threshold B is a threshold for determining whether the battery 5 is in a charging state close to full discharge. If the SOC of the battery 5 is less than the full-discharge determination threshold B (No in S2), it is assumed that the battery 5 is in a full-discharge state and the process proceeds to S10. If the SOC of the battery 5 is equal to or greater than the full-discharge determination threshold B (Yes in S2), it is assumed that the battery 5 is not in a full-discharge state and the process proceeds to S3.

[0041] In S3, the power comparison unit 67 compares the SOC of the battery 5 with the charge / discharge determination threshold C. The charge / discharge determination threshold C is a threshold for determining whether to prioritize charging or discharging the battery 5 in subsequent processing, and is less than the full-charge determination threshold A and greater than the full-discharge determination threshold B. If the SOC of the battery 5 is greater than the charge / discharge determination threshold C (No in S3), it is determined that discharging of the battery 5 should be prioritized and the process proceeds to S8. If the SOC of the battery 5 is equal to or less than the charge / discharge determination threshold C (Yes in S3), it is determined that charging of the battery 5 should be prioritized and the process proceeds to S4.

[0042] In S4, it is determined whether the battery 5 can be charged. Specifically, the fuel loss amount α corresponding to the loss during charging of the battery 5, which corresponds to “(B) Fuel consumption for loss” in FIG. 5, is compared with the fuel savings amount β by the optimal output (85%) corresponding to “(A) Improvement in fuel consumption” in FIG. 5. The fuel loss amount α is expressed as “(P B -P L )×(1-η PC )×F min ”, and the fuel savings amount β is expressed as “P L ×(F n -F min )”. Here, P B is the optimal output (850 kW in FIG. 5), P L is the required power of the in-ship load 3, η PC is the efficiency of the AC / DC conversion unit 51, F min is the minimum fuel consumption (198.40 g / kWh in FIG. 5), and F n is the current fuel consumption.

[0043] When the fuel loss amount α is less than or equal to the fuel savings amount β (No in S4), by operating the diesel generator 4 at the optimum output P B a fuel savings effect exceeding the charging loss of the battery 5 can be obtained. Therefore, the battery 5 is charged in S11, and the diesel generator 4 (DG: Diesel Generator) is operated at the optimum output P B or the minimum fuel consumption F min In this way, when the fuel savings amount β exceeds the fuel loss amount α, the power generation control unit 64 changes the operating conditions of the diesel generator 4 to the optimum output P B in S12 and charges the battery 5 with the surplus power generated by the diesel generator 4 in S11. In S11, the power generation control unit 64 determines the current supplied to the battery 5 within a range where the frequency of the AC power on the power bus 2 does not change significantly and generates a current command for the AC / DC conversion unit 51.

[0044] When the fuel loss amount α is greater than the fuel savings amount β (Yes in S4), the charging loss of the battery 5 exceeds the fuel savings effect obtained by operating the diesel generator 4 at the optimum output P B so the process proceeds to S5 without charging the battery 5. In this way, when the change unit 62 attempts to change the operating conditions of the diesel generator 4 to the optimum output P B in S12, even if the current fuel consumption per unit generated energy calculated by the calculation unit 61 under the current operating conditions before the change is greater than the minimum fuel consumption per unit generated energy calculated by the calculation unit 61 under the optimum operating conditions after the change, if the fuel loss amount α corresponding to the loss of the battery 5 obtained by the loss acquisition unit 65 exceeds the fuel savings amount β obtained by subtracting the minimum fuel consumption from the current fuel consumption, the change from the current operating conditions to the optimum operating conditions is not made.

[0045] In S5, it is determined whether the battery 5 can be discharged. Specifically, the current fuel consumption γ is compared with the fuel consumption δ required to charge the power to be discharged from the battery 5. The current fuel consumption γ is expressed as "F n ×P L " and the fuel consumption δ during charging is "PL ×F ave / η PC 」 is expressed as follows. Here, F ave is the average fuel consumption of the diesel generator 4 during charging.

[0046] When the current fuel consumption γ is greater than or equal to the fuel consumption δ during charging (No in S5), since a fuel-saving effect can be obtained by discharging the battery 5, the process proceeds to S14 for discharging. When the current fuel consumption γ is less than the fuel consumption δ during charging (Yes in S5), since the fuel consumption can be suppressed by supplying the required power of the in-ship load 3 only with the diesel generator 4 without discharging the battery 5, the charging and discharging of the battery 5 are not executed in S6, and in S7, the diesel generator 4 is operated with the current output or fuel consumption F n as it is. Thus, when the operating conditions of the diesel generator 4 are not changed in S7, the power generation control unit 64 does not charge or discharge the battery 5 in S6.

[0047] In S8 that branches from S3 when the discharge of the battery 5 should be prioritized (SOC > C), it is determined whether the battery 5 can be discharged based on the comparison of the current fuel consumption γ and the fuel consumption δ during charging, similar to S5. When the current fuel consumption γ is greater than or equal to the fuel consumption δ during charging (No in S8), since a fuel-saving effect can be obtained by discharging the battery 5, the process proceeds to S14 for discharging. When the current fuel consumption γ is less than the fuel consumption δ during charging (Yes in S8), since the fuel consumption can be suppressed without discharging the battery 5, the process proceeds to S9 without discharging the battery 5.

[0048] In S9, it is determined whether the battery 5 can be charged based on the comparison of the fuel loss amount α corresponding to the loss during charging of the battery 5 and the fuel savings amount β due to the optimal output, similar to S4. When the fuel loss amount α is less than or equal to the fuel savings amount β (No in S9), by operating the diesel generator 4 at the optimal output P B a fuel-saving effect exceeding the charging loss of the battery 5 can be obtained, so the battery 5 is charged in S11, and the diesel generator 4 is operated at the optimal output P B or the minimum fuel consumption F minIt is operated. When the fuel loss amount α is greater than the fuel savings amount β (Yes in S9), the charging loss of the battery 5 exceeds the fuel savings effect by operating the diesel generator 4 at the optimal output P B Therefore, the battery 5 proceeds to S6 without being charged.

[0049] In S10 that branches from S2 when the battery 5 is in a fully discharged state (SOC < B), similar to S4, it is determined whether the battery 5 can be charged based on a comparison of the fuel loss amount α corresponding to the loss during charging of the battery 5 and the fuel savings amount β by the optimal output. When the fuel loss amount α is less than or equal to the fuel savings amount β (No in S10), by operating the diesel generator 4 at the optimal output P B Since a fuel savings effect exceeding the charging loss of the battery 5 can be obtained, the battery 5 is charged in S11, and the diesel generator 4 is operated at the optimal output P B or the minimum fuel consumption F min It is operated. When the fuel loss amount α is greater than the fuel savings amount β (Yes in S10), the charging loss of the battery 5 exceeds the fuel savings effect by operating the diesel generator 4 at the optimal output P B Therefore, the battery 5 proceeds to S6 without being charged.

[0050] In S13 that branches from S1 when the battery 5 is in a fully charged state (SOC > A), similar to S5, it is determined whether the battery 5 can be discharged based on a comparison of the current fuel consumption γ and the fuel consumption δ during charging. When the current fuel consumption γ is greater than or equal to the fuel consumption δ during charging (No in S13), since a fuel savings effect can be obtained by discharging the battery 5, it proceeds to S14 for discharging. When the current fuel consumption γ is less than the fuel consumption δ during charging (Yes in S13), since the fuel consumption can be suppressed without discharging the battery 5, the battery 5 proceeds to S6 without being discharged.

[0051] In S14 for the discharge process of the battery 5, the maximum output P of the battery 5 c and the required power P of the in-ship load 3 L are compared by the power comparison unit 67. The maximum output P of the battery 5c is the required power P of the on - board load 3 L In the case above (No in S14), since the required power P of the on - board load 3 L can be covered by the battery 5 alone, the discharge of the battery 5 is executed at S18, and the diesel generator 4 is stopped at S19. Thus, when the charge amount or the discharge - available amount P c of the battery 5 is greater than or equal to the required power P of the on - board load 3 L the power generation control unit 64 stops the diesel generator 4 and supplies the power of the battery 5 to the on - board load 3. When the maximum output P c of the battery 5 is less than the required power P of the on - board load 3 L (Yes in S14), since the required power P of the on - board load 3 L cannot be covered by the battery 5 alone, the diesel generator 4 does not stop and proceeds to S15.

[0052] At S15, the required power P of the on - board load 3 L and the optimum output P of the diesel generator 4 B are compared by the power comparison unit 67. When the required power P of the on - board load 3 L is less than or equal to the optimum output P of the diesel generator 4 B (No in S15), since the required power P of the on - board load 3 L can be covered by the diesel generator 4 alone, the charge - discharge of the battery 5 is not executed at S6, and the diesel generator 4 is operated at the current fuel consumption F n or the minimum fuel consumption F min . When the required power P of the on - board load 3 L is greater than the optimum output P of the diesel generator 4 B (Yes in S15), since the required power P of the on - board load 3 L cannot be covered by the battery 5 alone, at S16, the required power P of the on - board load 3 is covered by the combination of the battery 5 to be discharged and the diesel generator 4 operated at the optimum output P B at S17. Thus, when the power generation amount P L of the diesel generator 4 is less than the required power P of the on - board load 3 B the power generation control unit 64 operates at the optimum output P L when the charge amount or the discharge - available amount P of the battery 5 is greater than or equal to the required power P of the on - board load 3, the power generation control unit 64 stops the diesel generator 4 and supplies the power of the battery 5 to the on - board load 3. When the maximum output P of the battery 5 is less than the required power P of the on - board load 3 (Yes in S14), since the required power P of the on - board load 3 cannot be covered by the battery 5 alone, the diesel generator 4 does not stop and proceeds to S15. At S15, the required power P of the on - board load 3 and the optimum output P of the diesel generator 4 are compared by the power comparison unit 67. When the required power P of the on - board load 3 is less than or equal to the optimum output P of the diesel generator 4 (No in S15), since the required power P of the on - board load 3 can be covered by the diesel generator 4 alone, the charge - discharge of the battery 5 is not executed at S6, and the diesel generator 4 is operated at the current fuel consumption F or the minimum fuel consumption F. When the required power P of the on - board load 3 is greater than the optimum output P of the diesel generator 4 (Yes in S15), since the required power P of the on - board load 3 cannot be covered by the battery 5 alone, at S16, the required power P of the on - board load 3 is covered by the combination of the battery 5 to be discharged and the diesel generator 4 operated at the optimum output P at S17. Thus, when the power generation amount P of the diesel generator 4 is less than the required power P of the on - board load 3, the power generation control unit 64 operates at the optimum output P BThe power generated by operating the diesel generator 4 is supplied to the on-board load 3, and the power charged in the battery 5 is also supplied to the on-board load 3.

[0053] As described above, the present invention has been described based on the embodiments. The embodiments are examples, and it is understood by those skilled in the art that various modifications are possible for each component and the combination of each processing process, and such modifications are also within the scope of the present invention.

[0054] In the embodiment, the power generation control device 6 in the power supply system 1 for ships has been described. However, the application target of the power generation control device of the present invention is not limited to ships. For example, the power generation control device of the present invention may be applied to the power supply systems of other transportation devices such as vehicles and aircraft.

[0055] Note that the functional configurations of the respective devices described in the embodiments can be realized by hardware resources or software resources, or by the cooperation of hardware resources and software resources. As hardware resources, a processor, ROM, RAM, and other LSIs can be used. As software resources, programs such as an operating system and an application can be used.

[0056] Among the embodiments disclosed in this specification, those in which a plurality of functions are provided dispersedly may have some or all of the plurality of functions provided in an aggregated manner. Conversely, those in which a plurality of functions are provided in an aggregated manner can be provided such that some or all of the plurality of functions are dispersed. Regardless of whether the functions are aggregated or dispersed, it is only necessary to be configured so that the object of the invention can be achieved.

Description of Reference Numerals

[0057] 1 Power supply system, 2 Power bus, 3 On-board load, 4 Diesel generator, 5 Battery, 6 Power generation control device, 41 Engine unit, 42 Power generation unit, 51 AC / DC conversion unit, 61 Calculation unit, 62 Change unit, 63 Identification unit, 64 Power generation control unit, 65 Loss acquisition unit, 66 Power measurement unit, 67 Power comparison unit.

Claims

1. A calculation unit that calculates the fuel consumption per unit generated energy of a generator having an engine unit that outputs rotational power by burning the input fuel and a power generation unit that converts the rotational power into electric power; A change unit that changes the operating conditions of the generator so as to change the output of the generator; A specific unit that compares the fuel consumption per unit generated energy calculated by the calculation unit under the operating conditions before the change with the fuel consumption per unit generated energy calculated by the calculation unit under the operating conditions after the change, and specifies the operating conditions with the lower fuel consumption; A power generation control unit that operates the generator under the specified operating conditions; comprising; The generator is provided on a ship, The electric power generated by the generator is supplied to the power bus in the ship, Further comprising a battery that can charge the electric power generated by the generator and discharge to the power bus, When the operating conditions are changed by the change unit, the power generation control unit controls the charging and discharging of the battery so that the rotational speed of the engine unit is kept constant, The change unit is a power generation control device that changes the operating conditions of the generator when the charge amount of the battery is equal to or greater than a predetermined value.

2. A calculation unit that calculates the fuel consumption per unit generated energy of a generator having an engine unit that outputs rotational power by burning the input fuel and a power generation unit that converts the rotational power into electric power; A change unit that changes the operating conditions of the generator so as to change the output of the generator; A specific unit that compares the fuel consumption per unit generated energy calculated by the calculation unit under the operating conditions before the change with the fuel consumption per unit generated energy calculated by the calculation unit under the operating conditions after the change, and specifies the operating conditions with the lower fuel consumption; A power generation control unit that operates the generator under the specified operating conditions; comprising; The generator is provided on a ship, The power generated by the generator is supplied to a power bus within the ship, The changing unit is a power generation control device that changes the operating conditions of the generator so as to change the output of the generator in response to the ship being refueled.

3. A calculation unit that calculates the fuel consumption per unit generated energy of a generator having an engine unit that outputs rotational power by combustion of the fuel input and a power generation unit that converts the rotational power into electric power, A changing unit that changes the operating conditions of the generator so as to change the output of the generator, A specifying unit that compares the fuel consumption per unit generated energy calculated by the calculation unit under the operating conditions before the change and the fuel consumption per unit generated energy calculated by the calculation unit under the operating conditions after the change, and specifies the operating conditions with the lower fuel consumption, A power generation control unit that operates the generator under the specified operating conditions, and is provided with, The generator is provided on a ship, The power generated by the generator is supplied to a power bus within the ship, The changing unit is a power generation control device that changes the operating conditions of the generator so as to change the output of the generator in response to a change in the current position of the ship.

4. A calculation unit that calculates the fuel consumption per unit generated energy of a generator having an engine unit that outputs rotational power by combustion of the fuel input and a power generation unit that converts the rotational power into electric power, A changing unit that changes the operating conditions of the generator so as to change the output of the generator, A specifying unit that compares the fuel consumption per unit generated energy calculated by the calculation unit under the operating conditions before the change and the fuel consumption per unit generated energy calculated by the calculation unit under the operating conditions after the change, and specifies the operating conditions with the lower fuel consumption, A power generation control unit that operates the generator under the specified operating conditions, comprising, the generator is provided on a ship, the power generated by the generator is supplied to a power bus in the ship, the generator includes a first generator and a second generator, The changing unit is a power generation control device that changes the operating conditions of the second generator so as to change the output of the second generator in response to switching the generator that supplies power to the power bus from the first generator to the second generator.

5. A calculation unit that calculates the fuel consumption per unit generated energy of a generator having an engine unit that outputs rotational power by combustion of the input fuel and a power generation unit that converts the rotational power into electric power, a changing unit that changes the operating conditions of the generator so as to change the output of the generator, a specifying unit that compares the fuel consumption per unit generated energy calculated by the calculation unit under the operating conditions before the change with the fuel consumption per unit generated energy calculated by the calculation unit under the operating conditions after the change, and specifies the operating conditions with the lower fuel consumption; a power generation control unit that operates the generator under the specified operating conditions, comprising, the generator is provided on a ship, the power generated by the generator is supplied to a power bus in the ship, further comprising a loss acquisition unit that acquires at least one of the losses during charging and discharging in a rechargeable battery for surplus power exceeding the required power of the load among the power generated by the generator. When the changing unit changes the operating conditions of the generator from the first operating conditions to the second operating conditions, even if the first fuel consumption per unit generated energy calculated by the calculating unit under the first operating conditions is greater than the second fuel consumption per unit generated energy calculated by the calculating unit under the second operating conditions, if the fuel loss amount corresponding to the loss of the battery acquired by the loss acquisition unit exceeds the fuel savings amount obtained by subtracting the second fuel consumption from the first fuel consumption, the power generation control device does not change from the first operating conditions to the second operating conditions.

6. The power generation control unit does not perform at least either charging or discharging of the battery when operating the generator under the first operating conditions. The power generation control device according to claim 5.

7. When the fuel savings amount exceeds the fuel loss amount during charging of the battery, the power generation control unit changes from the first operating conditions to the second operating conditions and charges the battery with surplus power generated by the generator. The power generation control device according to claim 5 or 6.

8. The loss acquisition unit calculates the loss in the battery based on the current command that the power generation control unit sends to the battery and the state of charge of the battery. The power generation control device according to any one of claims 5 to 7.

9. The power generation control device further includes a power measurement unit that measures the input AC power and the output DC power of a power conversion unit that converts the AC power generated by the generator into DC power and supplies it to the battery. The loss acquisition unit calculates the loss in the battery based on the input AC power and the output DC power. The power generation control device according to any one of claims 5 to 8.

10. When the changing unit changes the operating condition of the generator from the first operating condition to the second operating condition, if the first fuel consumption per unit generated energy calculated by the calculating unit under the first operating condition is greater than the second fuel consumption per unit generated energy calculated by the calculating unit under the second operating condition, the changing unit changes the operating condition of the generator to a third operating condition so that the output of the generator further changes from the second operating condition. If the third fuel consumption per unit generated energy calculated by the calculating unit under the third operating condition is greater than the second fuel consumption, the specifying unit specifies the second operating condition. The power generation control device according to any one of claims 1 to 9.

11. The changing unit changes the operating condition so as to change at least one of the rotational speed and torque of the engine unit. The power generation control device according to any one of claims 1 to 10.

12. The changing unit determines the amount of change in at least one of the rotational speed and torque of the engine unit according to at least one of the temperature of the engine unit, the type of fuel, and the state of the nozzle that injects the fuel into the engine unit. The power generation control device according to claim 11.

13. The power generation control device further includes a power comparison unit that compares the charge amount of a rechargeable battery with the required power of a load, which is charged with the electric power generated by the generator. When the charge amount of the battery is equal to or greater than the required power of the load, the power generation control unit stops the generator and supplies the power of the battery to the load. The power generation control device according to any one of claims 1 to 12.

14. The power generation control device further includes a power comparison unit that compares the power generation amount of the generator under the operating condition specified by the specifying unit with the required power of the load. When the power generation amount of the generator under the operation conditions specified by the specifying unit is less than the required power of the load, the power generation control unit causes the load to be supplied with the power generated by operating the generator under the operation conditions, and causes the load to be supplied with the power charged in the rechargeable battery from the power generated by the generator. The power generation control device according to any one of claims 1 to 13.

15. A calculation step of calculating the fuel consumption per unit generated energy of a generator having an engine unit that outputs rotational power by combustion of the input fuel and a power generation unit that converts the rotational power into electric power, An alteration step of altering the operation conditions of the generator so as to change the output of the generator, A specifying step of comparing the fuel consumption per unit generated energy calculated in the calculating step under the operation conditions before alteration with the fuel consumption per unit generated energy calculated in the calculating step under the operation conditions after alteration, and specifying the operation conditions with the lower fuel consumption, A power generation control step of operating the generator under the specified operation conditions, comprising The generator is provided on a ship, The power generated by the generator is supplied to the power bus in the ship. A battery capable of charging the power generated by the generator and discharging to the power bus is further provided, The power generation control step controls the charge and discharge of the battery so that the rotational speed of the engine unit is kept constant when the operation conditions are changed by the alteration step, The alteration step is a power generation control method for altering the operation conditions of the generator when the charge amount of the battery is equal to or more than a predetermined value.

16. A calculation step of calculating the fuel consumption per unit generated energy of a generator having an engine unit that outputs rotational power by combustion of the input fuel and a power generation unit that converts the rotational power into electric power, A changing step of changing the operating conditions of the generator so as to change the output of the generator; A specifying step of comparing the fuel consumption per unit generated energy calculated in the calculating step under the operating conditions before the change with the fuel consumption per unit generated energy calculated in the calculating step under the operating conditions after the change, and specifying the operating conditions with the lower fuel consumption; A power generation control step of operating the generator under the specified operating conditions; Causing a computer to execute; The generator is provided on a ship; The electric power generated by the generator is supplied to a power bus in the ship; A battery capable of charging the electric power generated by the generator and discharging to the power bus is further provided; The power generation control step controls charging and discharging of the battery so that the rotational speed of the engine unit is kept constant when the operating conditions are changed by the changing step; The changing step is a power generation control program for changing the operating conditions of the generator when the charge amount of the battery is equal to or more than a predetermined value.

Images