JP4690914B2 - Ship power supply system - Google Patents

Description

  The present invention relates to a ship power supply system that supplies outputs of a plurality of generators to an inverter and a load that drive an electric motor via buses.

Conventional ship power supply systems have multiple generators with a fixed capacity that are suitable for the load device, avoiding redundancy and maintaining power generator maintenance, and connecting their outputs to a common ship bus. It was. Furthermore, necessary power is supplied to the load by appropriately operating the generators in parallel according to the capacity of the load device.
For example, in the technique disclosed in Patent Document 1, a plurality of general loads and a plurality of generators respectively connected to a plurality of main machines are connected to a general power supply bus. In this technology, a circuit breaker and a power converter are connected in series between a power propulsion bus (AC bus) connected to an inverter that drives the propulsion motor and a general power bus connected to a general load. ing. As a result, the back power generated when the propulsion motor is rapidly reversed (during regenerative operation) is supplied to the general load via the power converter.
JP 7-315293 A (FIG. 1)

  In some cases, it is necessary to connect a large-capacity load with instantaneous load fluctuations or a load in which no load condition exists intermittently to a conventional power supply system for ships. In this case, the general load device for a ship and a large capacity load with instantaneous load fluctuations or a load device having an intermittent no-load state are connected by a common AC bus. At this time, if a load device with a large load fluctuation is connected, the operation balance of the generators connected in parallel may be lost, and stable power supply may be difficult.

  The technique of Patent Document 1 is to supply a back power to a general load through a power conversion device by turning on a circuit breaker during rapid reverse rotation of a propulsion motor. For this reason, since the circuit breaker is normally open, the generator that supplies power to the propulsion motor is not premised on supplying power to the general load.

  Therefore, the present invention provides a power supply system that supplies stable and highly efficient power that is not affected by a voltage drop due to instantaneous load fluctuations to a load device in which instantaneous load fluctuations and intermittent no-load states exist. This is the issue.

To solve the above problems, the present onset Ming, AC power multiple generators except the spare machine to generate electricity via a common bus, the inverter and the instantaneous variations and for driving the electric motor and intermittent unloaded condition A power supply system for a ship that supplies a plurality of loads including a variable load , wherein the bus is an AC bus that supplies AC power generated by some of the generators to the inverter. And another bus that supplies AC power generated by another generator to the variable load, and connects between the output side of the generator connected to the other bus and the AC bus. A switch is provided, and the switch is opened when instantaneous fluctuations of the variable load are continuously generated, and the switch is short-circuited when the variable load is continuously unloaded.

  The present invention provides a power supply system that supplies stable and highly efficient electric power that is not affected by a voltage drop due to instantaneous load fluctuations to a load device that has instantaneous load fluctuations and intermittent no-load conditions. it can.

(Summary of Invention)
An outline of the invention will be described with reference to FIG.
The plurality of main machines 10 and 11 and the generators 20 and 21 supply power to the variable loads 60 and 61 via the DC bus 44. The main engines 12 and 13 and the generators 22 and 23 supply power to the auxiliary motor 8 and the inboard general load 9 through the inboard bus 5. Further, switches 2 and 3 are provided between the generators 20 and 21 and the in-ship bus 5.

  Here, when the variable loads 60 and 61 are continuously in a no-load state, the generated power of the generators 20 and 21 and the generated power of the generators 22 and 23 are reduced by short-circuiting the switches 2 and 3. It is supplied to the auxiliary motor 8 or the general ship load 9. Here, when the instantaneous load current of the variable loads 60 and 61 is large and the no-load state occurs intermittently, the switches 2 and 3 are opened, and all of the generated power of the generators 20 and 21 is changed. , 61. Thereby, the influence of the instantaneous load current of the variable loads 60 and 61 does not affect the auxiliary motor 8 and the ship general load 9.

  Further, even if the power converters 41 and 42 are inserted between the generators 20 and 21 and the DC bus 44, the noise generated by the power converters 41 and 42 can be reduced by opening the switches 2 and 3. There is little influence on the motor 8 or the general ship load 9. Even if the switches 2 and 3 are short-circuited, the driving frequency of the power converters 41 and 42 is higher than the driving frequency of the inverter 7 driven in synchronization with the auxiliary motor 8, so that the auxiliary motor 8 and the general inboard The influence of noise on the load 9 is reduced.

  In addition, by operating the generators 20 and 21 or the generators 22 and 23 in parallel, the generator can be appropriately stopped according to the magnitude of the load power. Thereby, redundancy can be avoided and maintenance of the generators 20, 21, 22, and 23 is facilitated.

(First embodiment)
With reference to FIG. 1 again, details of the power supply system for a ship which is an embodiment of the present invention will be described.
The ship power supply system 1 is provided in a large ship and includes generators 20, 21, 22, and 23 mechanically connected to a plurality of main engines 10, 11, 12, and 13, and generators 20 and 21, respectively. Power converters 41 and 42 that are each connected to an output and convert AC voltage VAC to DC voltage VDC, and DC bus (other bus) 44 to which DC outputs of power converters 41 and 42 are connected in parallel The current sources 50 and 51 connected to the DC bus 44 and supplying current to the variable loads 60 and 61 having a large instantaneous load fluctuation, the ship internal bus 5 to which the outputs of the generators 22 and 23 are connected in common, and the ship An inverter (INV) 7 that is connected to the internal bus (AC bus) 5 and drives the auxiliary motor 8, a synchronizer 15 that synchronizes the generators 22 and 23, the outputs of the generators 20 and 21, and the on-board bus 5 Inserted between each A pitch 2,3, and a. Here, when the switches 2 and 3 are short-circuited, the synchronization device 15 synchronizes the generators 20 and 21 as well. The inboard general load 9 is connected to the inboard bus 5.

  Here, the main machines 10, 11, 12, 13 are engines, and have rotational outputs corresponding to the output capacities of the generators 20, 21, 22, 23. Here, the main engines 10, 11, 12, 13 and the generators 20, 21, 22, 23 correspond to the output capacities of the variable loads 60, 61, the auxiliary motor 8, and the inboard general load 9. , Avoiding redundancy. For example, when four generators are installed in a ship, during normal operation, up to three generators are operated in parallel to supply power to the load, and the remaining one is a spare. By always in a standby state as a machine, the number of generators that can supply power to the load is set even if one generator fails. In addition, maintenance of the main units 10, 11, 12, 13 and the generators 20, 21, 22, 23 is facilitated.

  The variable loads 60 and 61 are large-capacity loads in which instantaneous load fluctuations are large and there is an intermittent no-load state.

  The power converters 41 and 42 are AC / DC converters that convert the AC voltage VAC into the DC voltage VDC, and the output voltage is a high voltage of a maximum voltage of 300V. The power converters 41 and 42 perform control so that the output voltages coincide with each other, and are connected in parallel to the DC bus 44. Moreover, the power converters 41 and 42 have an insulating function for maintaining insulation from the generators 20 and 21. Furthermore, the power converters 41 and 42 output the generators 20 and 21 having different voltages and frequencies in parallel on the output side of the power converters 41 and 42.

  The direct current sources 50 and 51 are for flowing current through the variable loads 60 and 61. Further, due to the difference in the characteristics of the speed control method of the main engine that drives the generators operated in parallel, the parallel operation balance is lost and the generators are less likely to stop. This avoids the problem that it is difficult to stably supply power. Further, by providing two sets of the main machines 10 and 11, the generators 20 and 21, and the power converters 41 and 42, even when the load fluctuation of any one of the variable loads 60 and 61 increases, The generators 20 and 21 and the power converters 41 and 42 function so as to supplement each other.

  For this reason, when it is necessary to supply power to a large-capacity load with instantaneous load fluctuations or a load device that has an intermittent no-load state, a dedicated generator or AC power source is converted to a DC power source. Although it is necessary to install a dedicated power converter and supply power, it is necessary to install a dedicated large-capacity generator and a dedicated large-capacity converter in the ship to increase the capacity of such load devices. However, in recent years, it is difficult to secure installation space due to the increasing trend of electrical equipment. Since the total load capacity cannot be covered by the generated power that can be generated by the combination of the main unit 10 and the generator 20, a combination of a plurality of main units and generators is required. Due to the installation space, it is difficult to install a dedicated main engine and generator corresponding to the variable loads 60 and 61 due to the installation space. The inboard general load 9 is a general load such as lighting, a ship control device, and a pump.

Next, the operation of this embodiment will be described.
In the normal state, the power supply system 1 for the ship is supplied with power from the main engines 10 and 11 through the generators 20 and 21 and the switches 2 and 3 to the bus 5 in the ship, or the AC voltage VAC is supplied to the power converters 41 and 42. Applied. Here, when the variable loads 60 and 61 are in a no-load state, the main engines 10, 11, 12, 13 and the generators 20, 21, 22, 23 are appropriately operated in parallel, and the inverter is connected via the ship internal bus 5 7, electric power is supplied to the auxiliary motor 8 or the inboard general load 9.

  On the other hand, the switches 2 and 3 are opened when supplying power to a large-capacity load accompanied by instantaneous load fluctuations or to fluctuating loads 60 and 61 that intermittently have no load. Thereby, the electric power generated by the generators 20 and 21 is supplied only to the power converters 41 and 42, and the inverter 7 and the inboard general load 9 are supplied with electric power by the generators 22 and 23.

  Here, with reference to FIG. 2, the load pattern of the variable loads 60 and 61 accompanied by the instantaneous load fluctuation or the load in which the no-load state exists intermittently will be described. In this figure, the horizontal axis represents time t (s), the vertical axis represents the generator output (Kw), and there are three main engines and three generators. This load pattern is a rectangular wave pattern that increases with a steep slope from the no-load state of the variable loads 60 and 61 to the total output P3 for the three generators, and transitions to the no-load state after a lapse of a predetermined time. The wave pattern is repeated at regular intervals. Here, depending on the load capacity of the variable loads 60 and 61, there may be a total output P2 for two generators or an output P1 for one generator.

  When the AC voltage VAC is supplied to the power converters 41 and 42, power is supplied to the DC power supply (current sources 50 and 51) from the power converters 41 and 42 that convert the AC voltage VAC into the DC voltage VDC. The DC power supply (current sources 50 and 51) supplies power to the variable loads 60 and 61.

  In addition, when the load is only the ship's general load 9, power is shared to the inverter 7, the auxiliary motor 8, and the ship's general load 9 via the ship's bus 5 by switching the switches 2 and 3 to the ship's bus. Is done.

  As described above, according to the present embodiment, it is caused by the difference in the characteristics of the generator when the generator output side is connected in parallel by switching the bus that supplies power according to the characteristics of the load. Reactive power to be lost. Here, the reactive power means that a main engine (diesel engine) mounted in a ship generally has a low rotational speed stability due to engine characteristics in a low load zone (no load), and a plurality of generators. , Reactive power that may flow to each generator due to rotational speed difference (phase difference) and voltage difference.

  Further, depending on the load, the generator 20 is connected to a large-capacity load accompanied by instantaneous load fluctuations from different buses (DC bus 44, in-vessel bus 5), or to fluctuating loads 60 and 61 in which no-load state exists intermittently. , 21, 22, 23, the generators 22, 23 for general loads do not stop and stable power supply becomes possible.

  Further, by inserting power converters 41 and 42 between the generators 20 and 21 and the DC bus 44 and connecting the generators 20 and 21 and the power converters 41 and 42 in parallel, the generator 20 , 21 can be operated regardless of the characteristics.

  Furthermore, by connecting in parallel on the output side of the power converters 41 and 42, the output efficiency of the power supply system for ships is improved. This is because the reactive power of the generators 20 and 21 generated due to the difference in the characteristics of the generators 20 and 21 when connected in parallel on the output side of the generators 20 and 21 is reduced. As for this, there is a method of increasing the number of generators 20 and 21 that are operated in parallel, but harmonic noise generated in the power converters 41 and 42 for supplying DC power to a large-capacity load is generated in the ship. It affects other general loads via the bus and causes problems such as malfunctions. Moreover, since it is a load apparatus which will be in a no-load state intermittently, reactive power will generate | occur | produce in the output of the generators 20 and 21 at the time of no load, and will cause the efficiency fall of the whole ship power supply system.

  In addition, it is possible to reduce the influence of voltage drop due to instantaneous load fluctuations and harmonic noise from the power converters 41 and 42. The reason is that by providing two buses (DC bus 44, ship's bus 5) and separating the system and switching the bus, the ship's general load 9 and a large capacity load with instantaneous load fluctuations or intermittent This is because it can be electrically separated from a load in which no load condition exists. This is because even if the switches 2 and 3 are short-circuited, the drive frequency of the power converters 41 and 42 is generally higher than the drive frequency of the inverter 7 synchronized with the auxiliary motor 8.

(Reference example)
Here, a reference example of the marine power supply system will be described with reference to FIG.
In the ship power supply system 4, the generators 20, 21, 22 and 23 are connected to a common ship bus 5 ′, and the ship bus 5 ′ is connected to a variable load 60 connected via power converters 41 and 42. , 61, an auxiliary motor 8 connected via an inverter 7, and an inboard general load 9 are supplied with AC power. Further, the generators 20, 21, 22 and 23 are operated synchronously using the synchronization device 15. The main engines 10, 11, 12, 13 and the generators 20, 21, 22, 23 are similar to the above embodiment in that the power of the variable loads 60, 61, the auxiliary motor 8, and the inboard general load 9 is the same. It corresponds to capacity.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications such as the following are possible.
(1) The above-described embodiment is not particularly limited as long as instantaneous power such as light emission of a flash lamp is large.
(2) In the above embodiment, when the variable loads 60 and 61 are not loaded, the output power of the generators 20 and 21 is not limited to the variable loads 60 and 61 by using the switches 2 and 3. Is supplied to the inverter 7 and the auxiliary motor 8 via the power converters 41 and 42 or the changeover switch for switching to the shipboard bus 5 to cut off the power supply to the variable loads 60 and 61 and Only 5 can be supplied with power.

It is a block diagram of the power supply system for ships which is one Embodiment of this invention. It is a figure which shows the generator output accompanying instantaneous load fluctuation | variation. It is a reference example of the power supply system for ships.

Explanation of symbols

1,4 Vessel power supply system 2,3 switch 5 Vessel internal bus (AC bus)
7 Inverter 8 Auxiliary motor 9 General inboard load 10, 11, 12, 13 Main machine 15 Synchronizer 20, 21, 22, 23 Generator 41, 42 Power converter 44 DC bus (other bus)
50, 51 Current source 60, 61 Variable load

Claims (5)

AC power generated by a plurality of generators excluding spare machines is converted into a plurality of loads including a variable load including an inverter that drives the motor and instantaneous fluctuations and an intermittent no-load state via a common bus. A power supply system for a ship,
The bus includes: an AC bus that supplies AC power generated by some of the generators to the inverter; and another bus that supplies AC power generated by another generator to the variable load. Consisting of
A switch for connecting between the output side of the generator connected to the other bus and the AC bus;
The switch is opened when the instantaneous variation of the variable load continuously occurs, and the switch is short-circuited when the variable load is continuously unloaded. Ship power system.   2. The marine power supply system according to claim 1, further comprising a power converter that is connected between the other bus and the generator and converts the AC power into DC power. A ship power supply system that supplies AC power generated by a plurality of generators to a plurality of loads and an inverter that drives the motor via a common bus,
The plurality of loads include fluctuating loads in which instantaneous fluctuations and intermittent no-load states exist,
The bus includes: an AC bus that supplies AC power generated by some of the generators to the inverter; and another bus that supplies AC power generated by another generator to the variable load. Consisting of
A switch for connecting between the output side of the generator connected to the other bus and the AC bus;
The switch is opened when instantaneous fluctuations of the variable load continuously occur, and the switch is short-circuited when the variable load is continuously unloaded,
A power converter connected between the other bus and the generator, for converting the AC power into DC power;
Driving frequency of the inverter, ship marine power systems that being lower than the drive frequency of the power converter. A ship power supply system that supplies AC power generated by a plurality of generators to a plurality of loads and an inverter that drives the motor via a common bus,
The plurality of loads include fluctuating loads in which instantaneous fluctuations and intermittent no-load states exist,
The bus includes: an AC bus that supplies AC power generated by some of the generators to the inverter; and another bus that supplies AC power generated by another generator to the variable load. Consisting of
A switch for connecting between the output side of the generator connected to the other bus and the AC bus;
The switch is opened when instantaneous fluctuations of the variable load continuously occur, and the switch is short-circuited when the variable load is continuously unloaded,
A general load is connected to the AC bus,
When at least the switch is open, the generator and the ship marine power systems and generator you characterized in that it is asynchronously driven which is connected to the AC bus connected to said other bus . A power supply system for a ship that supplies AC power generated by a plurality of generators to a plurality of loads and an inverter that drives the motor via a common bus,
The plurality of loads include fluctuating loads in which instantaneous fluctuations and intermittent no-load states exist,
The bus includes: an AC bus that supplies AC power generated by some of the generators to the inverter; and another bus that supplies AC power generated by another generator to the variable load. Consisting of
A switch for connecting between the output side of the generator connected to the other bus and the AC bus;
The switch is opened when instantaneous fluctuations of the variable load continuously occur, and the switch is short-circuited when the variable load is continuously unloaded,
The other of the generator which is connected to the bus, the ship marine power systems that being a plurality of generator asynchronously drives.

Images