JP2016222149A - Ship and power supply method for in-ship power supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of kinds of engines for power generation installed in a ship.SOLUTION: A ship 10A comprises: a main engine 21 capable of gas operation using a gas fuel; a propulsion machine 22 rotatively driven by the main engine 21; and one or more shaft generators 31 generating electricity with a driving power received from the main engine 21. The main engine 21 performs the gas operation when the main engine 21 is driving at low load so as to allow at least one of the shaft generators 31 to generate electricity using the rotary power of the main engine 21 to supply the electricity generated by at least the one of the shaft generators 31 to an in-ship main bus 32 included in an in-ship power system 3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a ship equipped with a main engine capable of using gas fuel and a method of supplying power to the ship's power system.

  2. Description of the Related Art Conventionally, a propulsion system including a shaft generator that uses the rotational power of a main engine is known for a ship equipped with a diesel engine as the main engine. Non-Patent Document 1 describes such a propulsion system.

  On pages 12 to 14 of Non-Patent Document 1, a main machine, a main propulsion machine connected to the main machine by a propulsion shaft, a shaft generator provided on the propulsion shaft, an auxiliary generator, and a bow propulsion machine are provided. Some typical marine propulsion systems and power systems are also shown. In this document, during navigation, the ship's power load increases due to the driving of the bow propulsion machine, etc., which is covered by the power generated by the shaft generator, and the output of the auxiliary generator is the capacity of the bow propulsion machine It is generally shown that auxiliary generators only provide power for basic power loads, such as ship occupancy areas.

  Meanwhile, emission regulations for sulfur oxides (SOx) are being strengthened in stages by the International Maritime Organization (IMO). Diesel engines that use conventional C heavy oil as fuel emit a large amount of SOx, so the regulations have been cleared by installing flue gas desulfurization equipment, but the generation of sludge, etc. that is expensive to process is minimized. Are being operated. Specifically, when a diesel engine is operated at a low load, the SOx per unit output greatly increases, so the auxiliary generator is stopped during navigation so that the engine is always operated at a high load. The main generator is kept at a high load by generating power with a shaft generator driven by the motor, and the main generator is stopped at the time of berthing, and the auxiliary generator is kept at a high load by generating electricity with a smaller auxiliary generator. I came.

I. C. Clark and M. Hancox, “Anchor Handling Tug Operations”, 2012 G. Marina & E. Gatti, “Large Power PWM IGBT Converter for Shaft Alternator Systems”, 35th Annual IEEE Power Electronics Specialists Conference, 2004

  However, a conventional ship equipped with a diesel engine as a main engine as described above has two types of engines for a shaft generator and an auxiliary generator, and these maintenances are complicated and require labor and cost. There was a problem.

  By the way, ships that employ gas engines as main engines are being built. The gas engine is an engine that is driven by natural gas as fuel. Since natural gas does not generate SOx during combustion, it is not necessary to provide a flue gas desulfurization device, and it is not necessary to keep the engine at a high load factor for SOx countermeasures. However, conventional gas engine ships have followed the configuration and operation of diesel engine ship propulsion systems, and no ship propulsion system utilizing this feature has been proposed. Therefore, the present invention proposes a ship equipped with a main engine that performs gas operation at least at a low load, such as a gas engine, and a shaft generator that uses the power of the main engine, and tries to reduce the above-described problems.

That is, the ship according to one aspect of the present invention is
A main engine capable of gas operation using gas fuel,
A propulsion unit driven by the rotational force transmitted from the main unit through the propulsion shaft;
A generator for supplying power to the main bus onboard,
The generator comprises only at least one shaft generator that generates electric power by utilizing rotation of the propulsion shaft.

The power supply method to the inboard power system according to one aspect of the present invention is a power supply method to the inboard power system of a ship equipped with a main engine capable of gas operation using gas fuel,
When the main engine is under a low load, the main engine is gas-operated, and power is generated by at least one shaft generator using the rotational power of the main engine. It is characterized by being supplied to the included main ship bus.

  According to the power supply method to the ship and its inboard power system, it is possible to cover the power demand of the inboard power system by generating power with the shaft generator when the main engine is under low load. Therefore, it is not necessary to use the main engine and the auxiliary generator engine separately for economic reasons, and the conventional auxiliary generator and auxiliary generator engine can be used on the ship by generating power using the power of the main engine during navigation and anchoring. Can be omitted.

  The ship is allowed to transmit power from the main engine to the shaft generator and the propulsion unit during navigation, and is prohibited from transmitting power from the main unit to the propulsion unit during berthing and from the main unit to the shaft generator. A clutch provided on the propulsion shaft that operates to allow transmission of power to the propulsion shaft may be further provided.

  According to the above, it is possible to generate shaft power by operating the main engine when the ship is anchored by the operation of the clutch.

  The ship is provided between the shaft generator and the inboard main bus, converts the AC frequency of the shaft generator into the frequency of the AC power of the inboard main bus, and converts the AC voltage of the shaft generator. You may further provide the power converter device which converts into the alternating voltage of the said inboard main bus-line.

  According to the above, since the shaft generator does not need to control the AC frequency supplied to the power converter to the AC frequency of the inboard main bus, the main engine can be operated at a variable speed. Thereby, the propeller pitch loss of a propulsion machine can be reduced.

  The ship includes a first power converter having an AC end connected to the inboard main bus, a second power converter having an AC end connected to the shaft generator, and a DC end of the first power converter. A power converter having a DC intermediate section connecting a DC terminal of the second power converter; a frequency detector for detecting a frequency of the inboard main bus; and a first voltage detection for detecting a voltage of the inboard main bus. And a second voltage detector for detecting the voltage of the DC intermediate part, and a power generation control device for controlling the output of the power converter. Here, the power generation control device determines that the frequency of the inboard main bus becomes a predetermined frequency target value based on the detection values of the frequency detector and the first voltage detector, and the voltage of the inboard main bus is a predetermined voltage. The output of the first power converter is controlled so as to be a target value, and the first intermediate voltage is set to a predetermined DC intermediate voltage target value based on the detection value of the second voltage detector. Two power converter outputs may be controlled.

  According to the above, since the output of the power conversion device is controlled so that the system frequency and the system voltage become the predetermined target values, the power conversion device can be operated independently.

  In the ship, the power generation control device may control the output of the first power converter based on a predetermined droop characteristic.

  According to the above, since the output of the power converter has a droop characteristic, a plurality of shaft generators can be connected to the inboard main mother ship and operated in parallel.

  In the ship, the inboard main bus can be connected to an onshore power source, and the power generation control device connects the onshore power source and the inboard main bus when the inboard main bus is connected to the onshore power source. The predetermined droop characteristic may be adjusted to synchronize.

  According to the above, when the inboard main bus is connected to the onshore power source, the power source can be switched from the shaft generator to the onshore power source without a power failure.

  The ship may further include a power storage device, and a stored power conversion device having an AC terminal connected to the inboard main bus and a DC terminal connected to the power storage device.

  Based on the above, it is possible to compensate for fluctuations in the generated power of the shaft generator due to fluctuations in the load on the main engine with the power discharged from the power storage device.

  Alternatively, the ship may further include a power storage device and a stored power conversion device in which one DC end is connected to the DC intermediate portion and the other DC end is connected to the power storage device.

  Based on the above, it is possible to compensate for fluctuations in the generated power of the shaft generator due to fluctuations in the load on the main engine with the power discharged from the power storage device.

  The stored power conversion device charges the power storage device when a predetermined load target value of the main unit exceeds a load of the propulsion unit, and the predetermined load target value of the main unit is lower than a load of the propulsion unit Sometimes the power storage device may be discharged.

  Based on the above, it is possible to compensate for fluctuations in the generated power of the shaft generator due to fluctuations in the load on the main engine with the power discharged from the power storage device.

  In the ship, the stored power conversion device charges the power storage device when the frequency of the inboard main bus exceeds a predetermined frequency target value or when the voltage of the inboard main bus exceeds a predetermined voltage target value. The power storage device may be discharged when the frequency of the inboard main bus is lower than the predetermined frequency target value or when the voltage of the inboard main bus is lower than the predetermined voltage target value.

  According to the above, it is possible to suppress fluctuations in the frequency or voltage of the inboard main bus without inducing load fluctuations in the main engine.

  In the above-mentioned ship, the stored power conversion device is configured so that, based on a predetermined droop characteristic, the frequency of the inboard main bus becomes a predetermined frequency target value, and the voltage of the inboard main bus becomes a predetermined voltage target value. The charging and discharging of the power storage device may be controlled.

  According to the above, fluctuations in the power generated by the shaft generator due to fluctuations in the load on the main engine are compensated by the power supplied from the power storage device. In addition, even if the main engine misfires, the power storage device is discharged and the power supply to the inboard bus is automatically continued. Therefore, stable power supply to the ship load can be performed.

  According to the present invention, it is not necessary to use different engines for power generation during navigation and at anchoring, and a conventional auxiliary generator can be omitted. Therefore, the types of engines for power generation can be reduced.

1 is a block diagram showing a schematic configuration of a ship propulsion system and a power system according to a first embodiment of the present invention. It is a block diagram which shows schematic structure of the ship propulsion system and electric power system which concern on the modification 1 of 1st Embodiment. It is a block diagram which shows schematic structure of the ship propulsion system and electric power system which concern on 2nd Embodiment of this invention. It is a block diagram which shows the structure of the control system of a shaft generator. It is a graph which shows the droop characteristic line set when controlling a shaft generator. 6 is a chart showing a relationship between main engine output and thrust when the main machine is operated at a fixed speed and variable speed operation. It is a block diagram which shows schematic structure of the ship propulsion system and electric power system which concern on the modification 1 of 2nd Embodiment. It is a block diagram which shows schematic structure of the ship propulsion system and electric power system which concern on 3rd Embodiment of this invention. It is a graph which shows the time-dependent change of the load of a main machine and a propulsion machine. It is a graph which shows the time-dependent change of the load of a main machine and a propulsion machine. It is a block diagram which shows the flow of a process of an electric power storage control apparatus. It is a block diagram which shows schematic structure of the ship propulsion system and electric power system which concern on the modification 1 of 3rd Embodiment.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. In the following description, the same or corresponding elements are denoted by the same reference symbols throughout all the drawings, and redundant description thereof is omitted.

[First Embodiment]
FIG. 1 is a block diagram showing a schematic configuration of a propulsion system 2 and a power system 3 of a ship 10A according to the first embodiment of the present invention, and FIG. 2 shows the propulsion of the ship 10A according to a modification 1 of the first embodiment. 2 is a block diagram illustrating a schematic configuration of a system 2 and a power system 3. FIG. As shown in FIG. 1, a ship 10 </ b> A according to the first embodiment includes a propulsion system 2 and a power system 3.

(Propulsion system 2)
The propulsion system 2 of the ship 10A is a mechanical propulsion type, and includes a main machine 21, a propulsion machine 22, a propulsion shaft 23 that mechanically connects the main machine 21 and the propulsion machine 22, and the like.

  The main machine 21 according to the present embodiment is a gas engine. However, the main engine 21 is not limited to a gas engine as long as it is an engine capable of gas operation using a gas fuel such as natural gas. For example, a dual fuel engine that can switch between a diesel operation using a liquid fuel such as heavy oil and a gas operation may be adopted as the main engine 21. The main machine 21 is gas-operated at least when the main machine 21 is under a low load.

  The propulsion device 22 gives propulsive force to the ship 10A such as a propeller. The propulsion device 22 according to the present embodiment is a variable pitch propeller, and can freely change the pitch angle from forward to reverse. The propulsion unit 22 is driven by the rotational force transmitted from the main unit 21 by the propulsion shaft 23. Here, the “propulsion shaft 23” represents a shaft system that transmits shaft output from the main unit 21 to the propulsion unit 22 including a propeller shaft, an intermediate shaft, a reduction gear (not shown), and the like.

(Power system 3)
The power system 3 of the ship 10A is composed of wiring, a generator connected to the wiring, load facilities, and the like. The power system 3 of the ship 10 </ b> A according to the present embodiment includes at least a shaft generator 31, an inboard main bus 32, an output line 34 connecting the shaft generator 31 and the inboard main bus 32, and at least the inboard main bus 32. One inboard load 35 and the like are provided. The inboard load 35 includes power consumed in the ship such as inboard lighting, air conditioning, bow thruster (head propulsion machine) and the like.

  The shaft generator 31 is a generator that generates electric power using the rotation of the propulsion shaft 23, that is, the rotational power of the main engine 21, and is provided on the propulsion shaft 23. The electric power generated by the shaft generator 31 is supplied to the inboard main bus 32 through the output line 34. The shaft generator 31 is not limited to the mode of being provided on the propulsion shaft 23 as shown in FIG. 1 and taking out rotational power directly from the propulsion shaft 23. As shown in FIG. The aspect which takes out rotational power through the provided reduction gear 27 may be sufficient.

  In the ship 10A having the above-described configuration, the main engine 21 is operated during both voyage and anchoring, and the shaft generator 31 generates power during both voyage and anchoring. As described above, the shaft generator 31 that generates power during both voyage and anchoring functions as a generator that generates power to cover the power demand in the ship when the ship 10A sails, and power in the ship when the ship 10A is anchored. It also has a function as a generator that generates electricity to cover demand. That is, the shaft generator 31 has a function as a conventional main generator and auxiliary generator. Therefore, the ship 10A is not equipped with an auxiliary generator and an engine for the auxiliary generator that the conventional ship has.

  When the thrust generated by the propulsion unit 22 is changed while maintaining the power generated by the shaft generator 31 when the main unit 21 is operated at a fixed rotational speed, the blade angle of the propulsion unit 22 is changed. However, instead of or in addition to the change of the blade angle, a continuously variable transmission device is provided in the power transmission path from the propulsion shaft 23 to the shaft generator 31 so that the rotational power input from the propulsion shaft 23 to the shaft generator 31 can be reduced. It may be adjusted.

  The marine vessel 10 </ b> A may include a clutch 26 that can switch between allowing and prohibiting transmission of power from the main engine 21 to the propulsion machine 22. The clutch 26 is provided downstream of the shaft generator 31 of the propulsion shaft 23 in the power transmission path. The clutch 26 is switched by an actuator (not shown) by automatic control or manual control.

  The clutch 26 connects the propulsion shaft 23 so as to allow transmission of power from the main engine 21 to the propulsion machine 22 and allow transmission of power from the main engine 21 to the shaft generator 31 when the marine vessel 10A navigates. To do. Further, the clutch 26 prohibits transmission of power from the main engine 21 to the propulsion machine 22 when the marine vessel 10A is anchored, and allows transmission of power from the main engine 21 to the shaft generator 31. Disconnect. At the time of berthing, after the clutch 26 is switched as described above, the main generator 21 performs gas operation, whereby the shaft generator 31 generates power.

  As described above, the marine vessel 10A of the present embodiment includes a main engine 21 capable of gas operation using gas fuel, and a propulsion apparatus 22 driven by the rotational force transmitted from the main apparatus 21 via the propulsion shaft 23. And a generator for supplying electric power to the inboard main bus 32. The generator includes at least one shaft generator 31 that generates electric power by utilizing the rotation of the propulsion shaft 23.

  In the power supply method for the inboard power system 3 of the present embodiment, the main engine 21 is gas-operated when the main engine 21 is under a low load, and power is generated by at least one shaft generator 31 using the rotational power of the main engine 21. The power generated by the at least one shaft generator 31 is supplied to the inboard main bus 32 included in the inboard power system 3.

  In the main engine 21 (for example, a gas engine) capable of gas operation, SOx is hardly generated during gas operation regardless of the load factor. Therefore, the main generator 21 capable of gas operation can be operated by gas operation at a low load and the shaft generator 31 can generate power. That is, power can be generated by the shaft generator 31 at the time of berthing in addition to the conventional navigation.

  According to the power supply method of the ship 10A and the inboard power system 3 of the present embodiment, it is not necessary to use the main engine and the auxiliary generator engine separately for reasons of environmental regulations and processing costs such as sludge. By generating electricity using the power of the main engine 21 at any time, the conventional auxiliary generator and auxiliary generator engine can be omitted. That is, the generator that supplies power to the inboard main bus 32 may be only one type of shaft generator 31. Therefore, since the conventional auxiliary generator and the auxiliary generator engine can be omitted, labor and cost required for these maintenance can be reduced.

  Further, the ship 10A of the present embodiment is allowed to transmit power from the main engine 21 to the shaft generator 31 and the propulsion unit 22 during navigation, and is prohibited from transmitting power from the main engine 21 to the propulsion unit 22 when anchored. A clutch 26 is further provided on the propulsion shaft 23 that operates to allow transmission of power from the shaft 21 to the shaft generator 31.

  Thereby, at the time of berthing, the main engine 21 can be gas-operated and the shaft generator 31 can generate power while prohibiting transmission of power to the propulsion unit 22. Thereby, energy loss can be reduced. In addition, by generating power using the power of the main engine 21 both at the time of sailing and at the time of berthing, there is no need to use the main engine and the auxiliary generator engine separately, and the conventional auxiliary generator and auxiliary generator engine can be used. It can be omitted from the ship 10A.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. FIG. 3 is a block diagram showing a schematic configuration of the propulsion system 2 and the power system 3 of the ship 10B according to the second embodiment of the present invention, FIG. 4 is a block diagram showing a configuration of the control system of the shaft generator 31, and FIG. FIG. 6 is a chart showing a droop characteristic line set when controlling the shaft generator 31. FIG. 6 is a chart showing a relationship between the main engine output and thrust when the main machine 21 is operated at a fixed speed and at a variable speed. These are block diagrams which show schematic structure of the propulsion system 2 of the ship 10B and the electric power grid | system 3 which concern on the modification 1 of 2nd Embodiment.

  As shown in FIGS. 3 and 4, the ship 10 </ b> B according to the present embodiment further includes a power conversion device 25, a main engine control device 41, a power generation control device 42, and the like, in addition to the ship 10 </ b> A according to the first embodiment described above. It is characterized by providing. In the description of the present embodiment, the same or similar members as those in the first embodiment are denoted by the same reference numerals in the drawings, and the description thereof is omitted.

  The power converter 25 is a device that converts AC power of the shaft generator 31 into AC power of the inboard main bus 32.

  The power conversion device 25 according to the present embodiment includes a first power converter 25 a and a second power converter 25 b connected by a DC path 37. However, the power conversion device 25 is not limited to this configuration, and may have any conversion function as described above. For example, an AC-AC converter may be used as the power conversion device 25.

  The 1st power converter 25a is a system side power converter, and is constituted by an inverter, for example. The AC terminal of the first power converter 25a is connected to the inboard main bus 32 via the electric circuit 36, and the DC terminal is connected to the DC circuit 37 (DC intermediate part). The first power converter 25 a converts the DC power input from the DC path 37 into AC power and outputs the AC power to the inboard main bus 32.

  The 2nd power converter 25b is a generator side power converter, Comprising: For example, it is constituted by a converter. The direct current end of the second power converter 25 b is connected to the direct current path 37 (direct current intermediate part), and the alternating current end is connected to the shaft generator 31 via the electrical path 38. The second power converter 25 b converts the AC power input from the shaft generator 31 into DC power and outputs it to the DC path 37. Note that a capacitor may be connected to the DC path 37 so that fluctuations in the voltage of the DC path 37 may be smoothed.

  The main machine control device 41 is a device that controls the rotation speed of the main machine 21 and is connected to the main machine 21 and the power generation control device 42 by signal lines. The power generation control device 42 is a device that controls the shaft generator 31, and is connected to the main power control device 41 and the first power converter 25a and the second power converter 25b of the power conversion device 25 through signal lines. Yes. More specifically, the power generation control device 42 includes a first power converter control unit that controls the first power converter 25a and a second power converter control unit that controls the second power converter 25b. These control units may be configured as independent calculation control devices. In addition, each control apparatus 41 and 42 may be comprised by one arithmetic control apparatus, and may each be comprised by the separate arithmetic control apparatus. When each of these control devices 41 and 42 is constituted by one arithmetic control device, the function of each control device 41 and 42 is realized by a program stored in the one arithmetic control device.

  Various detectors such as a system frequency detector 46, a system voltage detector 47, a direct current intermediate voltage detector 48, a power detector 49, and a reactive power detector 50 are electrically connected to the power generation control device 42. Yes. Note that at least two of these detectors 46 to 50 may be combined.

  The system voltage detector 47 is a detector that detects the voltage of the inboard main bus 32 (that is, the voltage of the power system 3). Hereinafter, the voltage of the power system 3 may be referred to as “system voltage”.

  The system frequency detector 46 is a detector that detects the frequency of the inboard main bus 32 (that is, the frequency of the power system 3). Hereinafter, the frequency of the power system 3 may be referred to as “system frequency”. However, instead of the system frequency detector 46, an ammeter for detecting the current value of the electric power output from the power converter 25 to the inboard main bus 32 is provided, and the power generation control device 42 includes an ammeter and a system voltage detector 47. You may be comprised so that a system | strain frequency may be calculated | required using a detection result.

  The DC intermediate voltage detector 48 is a detector that detects the voltage of the DC path 37 (DC intermediate portion). Hereinafter, the voltage of the DC path 37 may be referred to as “DC intermediate voltage”.

  The power detector 49 is a detector that measures the effective power output from the power converter 25 to the inboard main bus 32. The reactive power detector 50 is a detector that measures reactive power output from the power converter 25 to the inboard main bus 32. The power exchanged between the shaft generator 31 and the inboard main bus 32 is composed of an active power component and a reactive power component. The active power is power that is consumed as power by the inboard load 35, and the reactive power is power that circulates in the power system 3 without being consumed as power. Instead of the power detector 49 and the reactive power detector 50, an ammeter for detecting the current output from the power converter 25 to the inboard main bus 32 is provided, and the power generation control device 42 detects the ammeter and the system voltage. The active power and the reactive power may be obtained based on the detection value of the device 47.

  Next, the control of the power conversion device 25 (shaft generator 31) by the power generation control device 42 will be described in detail.

  The power generation control device 42 controls the first power converter 25a so that the system frequency becomes a predetermined frequency target value and the system voltage becomes a predetermined voltage target value. Further, the power generation control device 42 controls the second power converter 25b so that the DC intermediate voltage is constant.

  In the above, it is desirable that the power generation control device 42 performs the droop control on the first power converter 25a. That is, it is desirable that the power generation control device 42 determines the frequency control target value and the voltage control target value based on given droop characteristics. The droop characteristic line is determined by the standard frequency or standard voltage of the power system 3, the active or reactive power command value for the shaft generator 31, the inclination, and the like, and is set in the power generation control device 42 in advance. However, the droop characteristic line may change in slope according to the active or reactive power command value.

  FIG. 5 is a chart showing a droop characteristic line set when the frequency of the shaft generator 31 is controlled. In the chart of FIG. 5, the vertical axis indicates the power generation frequency, and the horizontal axis indicates the generated power (that is, active power). The droop characteristic line shown in this chart has a characteristic that the generated frequency decreases as the generated power increases. The power generation control device 42 obtains a frequency target value based on a point on the droop characteristic line corresponding to the detected value of active power, and uses this as a system frequency target value for control. Similarly, the power generation control device 42 obtains a voltage target value corresponding to the detected value of reactive power based on the droop characteristic having the characteristic that the voltage of the generated power decreases as the reactive power increases, and obtains this voltage target value. Used as a target value for control. Furthermore, the power generation control device 42 calculates the output voltage and output current of the first power converter 25a from the system frequency target value, the system voltage target value, and the detected system frequency, system voltage, active power, reactive power, and the like. Ask.

  In the electric power system 3 described above, there is one shaft generator 31 connected to the inboard main bus 32. When the inboard load increases, the effective power generated by the shaft generator 31 increases, and the shaft is generated according to the droop characteristic. The generator 31 is stably operated in a state where the power generation frequency is slightly reduced. Thereby, the electric power grid | system 3 is stabilized by the system frequency which fell a little. Alternatively, a power management system may be provided to detect the system frequency and adjust the position of the droop characteristic line in FIG. 5 in the vertical direction. In this example, the power management system detects a decrease in the system frequency, adjusts the position of the droop characteristic line upward, and returns the system frequency to the original value.

  Next, it is assumed that two shaft generators 31 are connected to the inboard main bus 32, the load of one shaft generator 31 increases for some reason, and the load of the other shaft generator 31 decreases. In this case, according to the droop characteristic, the control target value of one frequency is lower than the system frequency, and the control target value of the other frequency is higher than the system frequency. As a result, one load is reduced and the other load is increased. As a result, the loads of both shaft generators 31 are equal, and the system frequency is stably operated at the original value. The same applies to the case where there are three or more shaft generators 31 connected to the inboard main bus 32.

  In the above description, increase / decrease in active power corresponding to increase / decrease in system frequency has been described, but the same applies to increase / decrease in reactive voltage corresponding to increase / decrease in system voltage. Since “droop control” is a well-known technique, a detailed description thereof will be omitted. For details of the droop control, refer to Non-Patent Document 2 and the like.

  As described above, the ship 10B of the present embodiment is provided between the shaft generator 31 and the inboard main bus 32, and converts the AC frequency of the shaft generator 31 into the AC frequency of the inboard main bus 32. The power converter 25 further converts the AC voltage of the shaft generator 31 into the AC voltage of the inboard main bus 32.

  According to the above, since the shaft generator 31 does not need to control the AC frequency supplied to the power converter 25 to the AC frequency of the inboard main bus 32, the main engine 21 can be operated at a variable speed. FIG. 6 is a chart showing the relationship between the main engine output and the thrust when the main machine 21 is operated at a fixed speed and at a variable speed. When the fixed rotation speed operation is performed, even if the thrust is 0, a large loss occurs because the resistance to the operation of the propulsion device 22 (for example, rotation of the propeller) is received. From this chart, it can be seen that if the main engine 21 is operated at a variable speed, a loss corresponding to a difference in thrust at a fixed speed operation can be reduced from a thrust at a variable speed operation.

  Further, the ship 10B according to the present embodiment includes a first power converter 25a having an AC end connected to the inboard main bus 32, a second power converter 25b having an AC end connected to the shaft generator 31, and a first power converter 25b. A power converter 25 having a DC path 37 (DC intermediate section) connecting the DC terminal of the first power converter 25a and the DC terminal of the second power converter 25b, and a system frequency detection for detecting the frequency of the inboard main bus 32 A detector 46, a system voltage detector 47 (first voltage detector) for detecting the voltage of the inboard main bus 32, a DC intermediate voltage detector 48 (second voltage detector) for detecting the voltage of the DC path 37, And a power generation control device 42 that controls the output of the power conversion device 25. The power generation control device 42 sets the frequency of the inboard main bus 32 to a predetermined frequency target value based on the detection values of the system frequency detector 46 and the system voltage detector 47, and sets the voltage of the inboard main bus 32 to the predetermined voltage target value. The second power converter 25b is controlled such that the output of the first power converter 25a is controlled so that the voltage of the DC path 37 becomes a predetermined DC intermediate voltage target value based on the detection value of the DC intermediate voltage detector 48. Is configured to control the output.

  Thereby, since the output of the power converter device 25 is controlled so that the system frequency and the system voltage become predetermined target values, the power converter device 25 can be operated independently. Further, the power quality of the inboard main bus 32 can be ensured.

  Furthermore, the power generation control device 42 according to the present embodiment is configured to control the output of the first power converter 25a based on a predetermined droop characteristic. The droop characteristic used in the present embodiment includes a droop characteristic having a characteristic that the frequency of the generated power of the shaft generator 31 decreases with an increase in the generated power (ie, active power) of the shaft generator 31, and the shaft This is a droop characteristic characterized in that the output voltage of the shaft generator 31 decreases with increasing reactive power of the generator 31.

  Thereby, since the output of the power converter device 25 has a droop characteristic, the power converter device 25 can perform both a self-sustained operation and a grid-connected operation, and can seamlessly switch between the self-sustained operation and the grid-connected operation. it can. Therefore, for example, as shown in FIG. 7, a plurality of shaft generators 31 can be connected to the inboard main bus 32 and the plurality of shaft generators 31 can be operated in parallel.

  Further, since the output of the power converter 25 has a droop characteristic as described above, the inboard main bus 32 can be connected to a land power source via the land power plug 80 as shown in FIG. When the inboard main bus 32 is connected to the onshore power source, the power source can be switched from the shaft generator 31 to the onshore power source without power failure. The power generation control device 42 is configured to adjust a predetermined droop characteristic so that the land power source and the ship main bus 32 are synchronized when the ship main bus 32 is connected to the land power source.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. FIG. 8 is a block diagram showing a schematic configuration of the propulsion system 2 and the power system 3 of the ship 10C according to the third embodiment of the present invention.

  As shown in FIG. 8, in the ship 10 </ b> C according to the third embodiment, the ship 10 </ b> C according to the second embodiment controls the power storage device 82, the stored power conversion device 83, and the stored power conversion device 83. The power storage control device 84 is further provided. In the description of the present embodiment, the same or similar members as those in the first and second embodiments described above are denoted by the same reference numerals in the drawings, and redundant description is omitted.

  The power storage device 82 is a battery, a capacitor, or the like that can extract DC power. The storage of electricity is sometimes called charging, and the taking out is sometimes called discharging.

  Further, the stored power conversion device 83 has one DC end connected to the DC path 37 of the power conversion device 25 and the other DC end connected to the power storage device 82. The stored power conversion device 83 is a so-called DC / DC converter, and charges the DC power from the DC path 37 to the power storage device 82 and discharges the DC power stored in the power storage device 82 to the DC path 37. To do.

  By providing the power storage device 82 in the power system 3, the power stored in the power storage device 82 can be supplied to the inboard main bus 32 in the event of a power failure in the ship. Therefore, recovery from a power failure can be performed promptly.

  The power storage control device 84 can exchange signals with the main engine control device 41. The power storage control device 84 can cause the stored power conversion device 83 to function so as to discharge or charge the power storage device 82 based on the load acting on the main machine 21. FIG. 9 and FIG. 10 are charts showing changes with time in the loads of the main engine 21 and the propulsion unit 22. 9 and 10, the vertical axis represents the load on the main engine 21 or the propulsion unit 22, and the horizontal axis represents time.

  The chart of FIG. 9 shows a control operation for improving fuel consumption by keeping the load of the main engine 21 constant regardless of the load fluctuation of the propulsion device. In FIG. 9, the target value of the load on the main unit 21 is constant, the load on the propulsion unit 22 fluctuates due to waves and the like, and is lower than the target value of the load on the main unit 21 from time t1 to time t2. Therefore, the power storage control device 84 causes the stored power conversion device 83 to function so as to charge the power storage device 82 between time t1 and time t2.

  The chart of FIG. 10 shows a control operation for improving the motion performance of the ship by increasing the load of the propulsion device at a rate of change exceeding the load fluctuation tracking performance of the main engine 21. In FIG. 10, the load of the propulsion device 22 gradually increases from time t3 to time t4 due to the operation of the propeller blade angle, whereas the target load value of the main device 21 is in accordance with the load fluctuation tracking performance of the main device 21. From time t3 to time t5, it is going to increase gradually. Time t4 is a time earlier than time t5. In this case, the increase in the load on the main unit 21 does not catch up with the increase in the load on the propulsion unit 22, and the load on the main unit 21 is lower than the load on the propulsion unit 22 from time t3 to time t5. Therefore, the power storage control device 84 causes the stored power conversion device 83 to function so as to discharge the power storage device 82 between time t3 and time t5.

  As described above, the power storage control device 84 charges the power storage device 82 when the load target value of the main unit 21 exceeds the load of the propulsion unit 22, and lowers the load target value of the main unit 21 below the load of the propulsion unit 22. When the power is stored, the stored power converter 83 is caused to function so as to discharge the power storage 82. The power storage control device 84 calculates the load on the main unit 21 calculated based on at least one of the information received from the main unit control unit 41 such as the blade angle command of the propulsion unit 22, the rotational speed of the main unit 21, and the fuel index, or the like. The load of the main unit 21 calculated based on the detection value of the detector that indirectly detects the load of the main unit 21 may be used for control. In addition, the power storage control device 84 calculates based on the load of the propulsion unit 22 obtained based on the detected rotation speed of the propulsion unit 22 or the operation position of an operation lever (not shown) that steers the ship 10C. The load of the propulsion unit 22 may be used for control.

  While the power storage device 82 discharges and charges as described above, the output of the first power converter 25a coincides with the load power on the ship, so the power for charging and discharging passes through the second power converter 25b. It becomes a fluctuation component of the generated power of the generator 31, that is, the load fluctuation of the main machine 21 can be compensated. In general, a gas engine has lower load fluctuation tracking performance than a diesel engine, and easily misfires. Therefore, it has been difficult to mount a gas engine, particularly a gas-fired engine as a main engine on a ship type such as a tugboat where the load on the main engine fluctuates relatively greatly. On the other hand, in the ship 10C, the main engine 21 that is a gas engine can have load fluctuation tracking performance that is not inferior to that of a diesel engine, and a gas engine, in particular, a gas-fired engine can be installed as a main engine of a ship. The problem can be reduced.

(Modification 1 of 3rd Embodiment)
Next, Modification 1 of the third embodiment will be described. FIG. 12 is a block diagram illustrating a schematic configuration of the propulsion system 2 and the power system 3 of the ship 10C according to the first modification of the third embodiment. In the description of this modification, the same or similar members as those in the above-described embodiment may be denoted by the same reference numerals in the drawings, and description thereof may be omitted.

  In the ship 10C according to the above-described third embodiment, the power storage device 82 is connected to the DC path 37 of the power conversion device 25. However, as shown in FIG. 12, the ship according to the first modification of the third embodiment. In 10C, the power storage device 82 is connected to the inboard main bus 32. More specifically, the ship 10 </ b> C according to the modified example 1 includes a power conversion device 25, a stored power conversion device 83 having an AC end connected to the inboard main bus 32 and a DC end connected to the power conversion device 25, And a power storage control device 84 that controls the power conversion device 83.

  The stored power conversion device 83 is a so-called inverter, converts the AC power of the inboard main bus 32 and charges the power storage device 82, and also stores the DC power stored in the power storage device 82 of the inboard main bus 32. It is converted into AC power and discharged.

  Further, the power storage control device 84 stores the power storage device 82 so as to be discharged or charged based on the frequency of the inboard main bus 32 (ie, the system frequency) or the voltage of the inboard main bus 32 (ie, the system voltage). The power conversion device 83 may be controlled. In this case, the power storage control device 84 is connected to the system frequency detector 46 and the system voltage detector 47, and outputs from these detectors are input. The power storage control device 84 is connected to a detector (not shown) that detects active power and reactive power output from the stored power converter 83, and outputs from these detectors are input. .

  FIG. 11 is a block diagram illustrating a processing flow of the power storage control device 84. The stored power conversion device 83 includes a power conversion circuit (not shown) composed of switching elements and a PWM (Pulse Width Modulation) generator 99 that controls the switching elements to be turned on and off. FIG. 11 shows a flow of generating a PWM signal to be given to the PWM generator 99 by the power storage control device 84.

  As shown in FIG. 11, the system frequency measurement value measured by the system frequency detector 46 is subtracted from the system frequency target value by the subtractor 91, and the output of the subtractor 91 passes through the high-pass filter, and the active power command value calculation unit ( PID) 92. A signal representing the active power command value output from the active power command value calculation unit 92 is input to the subtractor 93. The subtracter 93 subtracts the active power detected by the power detector 49 installed between the inboard main bus 32 and the stored power converter 83 from the active power command value. The output of the subtracter 93 is input to a q-axis voltage command calculation unit (PID) 94. A signal representing the q-axis voltage command output from the q-axis voltage command calculation unit 94 is input to the dq inverse converter 90.

  On the other hand, the system voltage detector measurement value measured by the system voltage detector 47 is subtracted from the system voltage target value by the subtracter 95, and the output of the subtractor 95 passes through a high-pass filter, and the reactive power command value calculation unit (PID) 96 Is input. A signal representing the reactive power command value output from the reactive power command value calculation unit 96 is input to the subtractor 97. The subtractor 97 subtracts the reactive power detected by the reactive power detector 50 installed between the inboard main bus 32 and the stored power converter 83 from the reactive power command value. The output of the subtractor 97 is input to a d-axis voltage command calculation unit (PID) 98. A signal representing the d-axis voltage command output from the d-axis voltage command calculation unit 98 is input to the dq inverse converter 90.

  The signal representing the q-axis voltage command and the signal representing the d-axis voltage command input to the dq inverse converter 90 are output to the PWM generator 99. The PWM generator 99 generates PWM signals corresponding to these signals. As a result of the generation of the PWM signal, the stored power conversion device 83 charges the power storage device 82 when the system frequency or system voltage exceeds the target value, and turns the power storage device 82 when the system frequency or system voltage falls below the target value. Functions to discharge.

  As described above, the power storage device 82 discharges and charges, thereby suppressing the fluctuation of the system frequency or the system voltage without inducing the load fluctuation of the main engine 21.

  Alternatively, the power storage device 82 may be discharged / charged by the droop control of the stored power conversion device 83 by the power storage control device 84.

  The droop control method of the stored power conversion device 83 by the power storage control device 84 is the same as the droop control method of the first power converter 25a of the power conversion device 25 by the power generation control device 42 in the above-described second embodiment. is there. In this droop control, the droop characteristic in which the output frequency of the power storage device 82 decreases as the discharge power (active power) of the power storage device 82 increases or the charging power (active power) decreases, and the discharge of the power storage device 82. A system frequency target value and a system voltage target value are determined using a droop characteristic in which the output voltage of the power storage device 82 decreases with an increase in power (reactive power) or a decrease in charging power (reactive power).

  As described above, in the ship 10C according to the first modification of the third embodiment, the droop control similar to that performed by the first power converter 25a of the power conversion device 25 is performed on the stored power conversion device 83 as well. The power demand of 35 can be shared between the power generated by the shaft generator 31 and the power discharged by the power storage device 82. The sharing ratio can be adjusted by changing the setting of the droop characteristic used for the control.

  Further, if the power generated by the shaft generator 31 is reduced or lost due to an abnormality in the main engine 21, the discharge power from the power storage device 82 to the inboard main bus 32 automatically increases, and the abnormality in the main engine 21 is resolved. If it does, it will return to the original state automatically. Thereby, the electric power feeding to ship electric power can be maintained without power failure. Furthermore, since the stored power conversion device 83 does not need to exchange information with other devices, a highly reliable system can be constructed.

  The preferred embodiment (and modification) of the present invention has been described above. From the foregoing description, many modifications and other embodiments of the present invention are obvious to one skilled in the art. Accordingly, the foregoing description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and / or function may be substantially changed without departing from the spirit of the invention.

2: Propulsion system 3: Inboard power systems 10A, 10B, 10C: Ship 21: Main engine 22: Propulsion machine 23: Propulsion shaft 25: Power converter 25a: First power converter 25b: Second power converter 26: Clutch 27 : Decelerator 31: Shaft generator 32: Inboard main bus 35: Inboard load 37: DC path 41: Main engine controller 42: Power generation controller 46: System frequency detector 47: System voltage detector 48: DC intermediate voltage detector 49: Power detector 50: Reactive power detector 80: Onshore power plug 82: Power storage device 83: Stored power converter 84: Power storage control device 90: dq inverse converters 91, 93, 95, 97: Subtractor 92 : Active power command value calculation unit 94: d-axis voltage command value calculation unit 96: Reactive power command value calculation unit 98: q-axis voltage command value calculation unit 99: PWM generator

Claims (12)

A main engine capable of gas operation using gas fuel,
A propulsion unit driven by the rotational force transmitted from the main unit through the propulsion shaft;
A generator for supplying power to the main bus onboard,
The generator consists of at least one shaft generator that generates electric power by utilizing the rotation of the propulsion shaft.
Ship.   Transmission of power from the main engine to the shaft generator and the propulsion unit is permitted during navigation, transmission of power from the main unit to the propulsion unit is prohibited during berthing, and transmission of power from the main unit to the shaft generator is prohibited. The marine vessel according to claim 1, further comprising a clutch provided on the propulsion shaft that operates to allow transmission. Provided between the shaft generator and the inboard main bus, and converts the AC frequency of the shaft generator into the AC frequency of the inboard main bus, and converts the AC voltage of the shaft generator into the AC of the inboard main bus. A power converter for converting the voltage into a voltage;
The ship according to claim 1 or 2. A first power converter with an AC terminal connected to the inboard main bus, a second power converter with an AC terminal connected to the shaft generator, and a DC terminal of the first power converter and the second power A power conversion device having a DC intermediate portion connecting the DC ends of the converter;
A frequency detector for detecting the frequency of the inboard main bus;
A first voltage detector for detecting the voltage of the inboard main bus;
A second voltage detector for detecting the voltage of the DC intermediate part;
A power generation control device for controlling the output of the power converter,
The power generation control device is configured such that the frequency of the inboard main bus becomes a predetermined frequency target value based on detection values of the frequency detector and the first voltage detector, and the voltage of the inboard main bus is set to a predetermined voltage target value. And controlling the output of the first power converter so that the voltage of the DC intermediate portion becomes a predetermined DC intermediate voltage target value based on the detection value of the second voltage detector. Control the output of the instrument,
The ship according to claim 1 or 2. The power generation control device controls the output of the first power converter based on a predetermined droop characteristic.
The ship according to claim 4. The inboard main bus can be connected to a land power source,
The said power generation control apparatus adjusts the said predetermined droop characteristic so that the said land power supply and the said ship main bus may be synchronized, when the said ship main bus is connected with the said land power supply. Ship. A power storage device;
A stored power conversion device having an AC terminal connected to the inboard main bus and a DC terminal connected to the power storage device;
The ship according to any one of claims 1 to 6. A power storage device;
A storage power conversion device in which one DC terminal is connected to the DC intermediate part and the other DC terminal is connected to the power storage device;
The ship according to any one of claims 4 to 6. The stored power conversion device charges the power storage device when a predetermined load target value of the main unit exceeds a load of the propulsion unit, and the predetermined load target value of the main unit is lower than a load of the propulsion unit Sometimes discharging the power storage device,
The ship according to claim 7 or 8. The stored power conversion device charges the power storage device when the frequency of the inboard main bus exceeds a predetermined frequency target value or when the voltage of the inboard main bus exceeds a predetermined voltage target value. Discharging the power storage device when a bus frequency is lower than the predetermined frequency target value or when a voltage of the inboard main bus is lower than the predetermined voltage target value;
The ship according to claim 7 or 8. The stored power conversion device is configured so that, based on a predetermined droop characteristic, the frequency of the inboard main bus is a predetermined frequency target value and the voltage of the inboard main bus is a predetermined voltage target value. Control charging and discharging,
The ship according to claim 7. A power supply method to an inboard power system of a ship equipped with a main engine capable of gas operation using gas fuel,
When the main engine is under a low load, the main engine is gas-operated, and the rotational power of the main engine is used to generate power with at least one shaft generator, and the generated power of the at least one shaft generator is supplied to the inboard power system. Is supplied to the main bus inboard included in the
Power supply method to the inboard power system.

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