NO165049B - PROCEDURE FOR CONTINUOUS SUPPLY OF A SHIP NET FROM A FREQUENTLY VARIABLE PROGRESS NETWORK ON SHIPS. - Google Patents

Description

The invention relates to a method for continuous supply of a ship's network according to the preamble of independent claim 1.

For drive units for ship nets, there will also be

gas, resp. steam turbines mostly used diesel engines. For various reasons, it is not possible to set the aggregate's revolutions below a certain limit.

If, for the operation of special vessels, it should also be possible to work at a lower rpm, there can i.a. electrical operation is used. In direct current operation, the direct current motor is usually driven via a rectifier by one or more operating voltage generators that work at constant voltage and frequency and are driven by suitable primary energy converters.

In this connection, it is possible to supply the ship's grid in parallel with voltage from the operating current rail. The drive unit can be operated in all four quadrants. The same applies to a three-phase propeller motor with intermediate circuit inverter.

It is also known to feed a motor in a propeller drive system via rectifiers within the entire rpm range and to drive the ship's mains from the operating current rail. This then has a constant voltage and frequency. In this connection, reference is made to the journal "Hansa", 1978, pages 43-57.

The rectifier in this system must be dimensioned for the propulsion propeller's overall effect. Generators and motors are thus larger in size. In the sub-rpm range, the primary energy converters work with poor efficiency.

A cost-effective solution without appreciable limitation of maneuverability consists in using a three-phase/three-phase starting inverter for the speed range that is not covered by the primary energy converters.

Fig. 1 shows in a torque/speed diagram the power characteristics m for the starter inverter, m for the pro-

u p

the pellet, mD for a diesel engine and mw for the primary converter.

The operating range available via the inverter is limited by m . Above the primary energy converter's minimum speed, the inverter is bypassed and the drive unit is driven as an electric shaft, as the propeller's speed can be set with that of the primary energy converter (cf. DE-PS 31 33 311.7).

With this system, it has so far not been possible to feed the ship's grid from the operational generator.

A method according to the introduction of the new claim 1 is known from the article "Elektrische Leistungsiibertra-gung Gasturbine-Propeller" in Schiff und Hafen 7/1974. On page 636, illustration 8 shows a propulsion system for fast container ships, in which a brushless motor is used. The constant supply of the ship's mains is via two frequency converters, so that the constant supply of the ship's mains from quay to quay is carried out via the static frequency converter. The frequency converter for the ship's mains makes the propulsion mains frequency. independent of the ship's mains frequency, so that the selected propulsion mains frequency of 50 Hz enables the direct connection of a turbine to a two-pole generator, as an intermediate transmission can then be dispensed with.

A task that forms the basis of the invention therefore lies in obtaining a method of the type mentioned at the outset, with which a propeller drive via electric shaft with starting inverter in all four quadrants while simultaneously feeding the ship's mains is ensured by means of a three-phase drive generator which is operated with variable voltage and frequency.

According to the invention, a method of this kind is characterized by the features indicated in the characteristic of claim 1.

In this connection, one starts from the recognition that the torque mw (Fig. 1) which, with an appropriately selected power of the primary energy converter, is available above the minimum speed, has such a large reserve just opposite the propeller's torque m that the ship's grid can be fed via the starter inverter , which is no longer needed here.

The device according to the invention exhibits significant advantages over known technology.

Thanks to the possibility of taking drive and ship mains power from a common unit that can be operated with cheap heavy oil, the overall efficiency is improved.

In addition, the unit is better utilized at partial speeds for the propeller engine, compared to a propulsion system with a rectifier for all speeds. The specific power consumption is lowered to 32% at 50% rpm and below.

In addition, there is an improvement in efficiency of approx. 2% when operating above the starting inverter's speed, as the inverter is no longer used for the propulsion system and its typical losses are eliminated.

By using a flanged ship's generator on the drive unit during starter inverter operation, electromagnetic disturbances (EM) on the ship's grid caused by the current converter are avoided. After commissioning of the system, the supply of the ship's network can then be taken over by the propulsion system's generator at nominal revolutions on the electric shaft. Here, a supply of the ship's grid via the inverter with its inevitable EM disturbances is only needed for a relatively short time during commissioning. This situation favors the use of this facility on research ships and the like, which in their operational area only sail with partial power and then with an undisturbed ship network.

In addition, the facility is applicable especially for ships

which require good maneuverability, such as ferries, supply ships, rescue ships, etc., which in the lower rpm range (n <0.5) save considerable costs for fuel,

Prop

Further designs of the invention are characterized in the subclaims.

An embodiment of the device according to the invention

is shown in the drawing.

Fig. 2 shows the arrangement of a propulsion system, and

fig. 3 shows in a diagram of fuel consumption that

function of the number of revolutions the characteristics for a drive system with full inverter and with starting inverter.

If rated frequency for the propeller motor 1 according to

to fig. 2 is chosen so that the propulsion generator 3 at the determined minimum speed of the primary energy converter 2 emits the ship's mains frequency at U/f = constant regulation,

the ship's mains can be fed via a transformer 4, while the engine

1 is operated frequency decoupled via the intermediate circuit converter or frequency converter 5...8. If the voltage is the same, the transformer may fall away.

If it is not constructively possible to choose the minimum frequency of the propulsion generator equal to the ship's mains frequency, it is possible to supply the ship's mains via a connected generator 9 which, with a corresponding number of poles, provides the necessary ship's mains frequency.

If the frequency converter is bypassed with the switch 10 at a required higher speed for the propeller motor 1, the inverter 11 disconnects the frequency converter 5...8 from the motor 1, and the synchronous compensator 12 to the frequency converter. The machine can already be started in advance with a starter motor or by closing switch 13 asynchronously from the ship's mains. Otherwise, it is driven up to the nominal frequency with the help of the frequency converter and the switch 13 is closed. The frequency converter then takes over the supply of the ship's mains.

If the inverter 6 in the frequency converter is mains-controlled, the synchronous compensator supplies the necessary commutation and control reactive power as well as the mains reactive power and ensures that the required current is supplied in the event of a short circuit. If the inverter is self-controlled, the synchronous compensator only needs to take over the corresponding reactive power and short-circuit current supply for the ship's grid.

If the frequency converter has taken over the ship's mains load, the transformer 4 or the generator 9 can be disconnected via the switches 15 and 14 respectively. The primary energy converter 2 can increase its speed and thus the speed of the propeller motor 1, during which the voltage is increased proportionally with the help of the generator 3. The frequency converter disconnects frequency and voltage. System-specific voltage spikes are smoothed out with a capacitor 7.8 which is connected in the DC intermediate circuit.

If the nominal frequency of the electric shaft is the same as the ship's mains frequency, the ship's mains can be synchronized with the propulsion mains at the nominal speed of the propeller and then via the transformer 4 connected to the switch 15. The frequency converter is separated from the ship's mains using a switch 11 or 13. The system enables quick reversal or emergency stop from high speed.

In that case, the switch 10 is opened and the brake switch 17 is closed. The motor 1 drives, regulated via its magnetization,

a defined current through the braking resistor 18. If the ship's grid is powered directly via the transformer 4, the frequency converter 5...8 must take over the supply of the ship's grid. For this purpose, the synchronous compensator must be run again if it does not run along

in advance. With switches 11 and 13 (if not already closed), the frequency converter is connected to the ship's mains. It can take over the load. The switch 15 is opened.

The number of revolutions for the primary energy converter 2 becomes

taken back to the minimum speed corresponding to the ship's mains frequency, and synchronized with the ship's mains.

Switch 14 or 15 are closed and 13 are opened. Thus, the frequency converter is ready for the supply for the propeller motor. Switch 11 is switched. Meanwhile, the engine decelerated

when braking on the resistor 18, and the brake switch 17 can be opened.

As soon as the frequency converter's dimensioning with respect to the torque allows it, the frequency converter transfers the motor from the 4th quadrant to the 3rd quadrant. Should it be necessary, the frequency converter as described above can be shunted with the switch 10 to give a higher number of revolutions in the opposite direction with a function as an electric shaft. For this case, the switch 10 must be designed as a phase-reversing switch.

The necessary connection system can be made easily when

it is taken into account that all the switches apart from switches 10, 17 and 20 can be connected to a de-energized state. As short-circuit protection, only switches 13, 20, 14/15 and 19 need to be dimensioned (14/15 are to be considered as alternatives). You can go

assuming that the transition from the maneuvering area n <0.5 to

3 ^ 3 prop

cruise speed and vice versa occur relatively rarely. The same applies to an emergency stop maneuver from full ship speed. The switching frequency when it comes to switches 10, 17, 11, 13, 14/15 is therefore very low, and one can count on long downtimes.

The wrestlers 19, 14/15 and 20 themselves wanted a traditional one

facilities are needed such as load switches and short-circuit protection.

In order to avoid strong frequency fluctuations on the generator 3 or 9, the propeller motor current in the direct current intermediate circuit via the rectifier 5 in the frequency converter 5...8 is so limited that the primary energy converter's speed remains approximately constant under load due to the propeller motor.

The advantage of this method lies in the fact that, in connection with full maneuverability of the propeller engine, it is possible to supply the ship's mains at 6% at nominal speed continuously from the propulsion system's drive unit. After agreement with the classification institutes, it will then be possible to save a ship's power supply unit.

The unit 16, which can be operated with diesel oil, will now only be needed for stand-by operation, for emergencies or in port.

This arrangement makes it possible to "push" the minimum permanent rpm for the main diesel engine by increasing the partial load in accordance with the propeller power curve with the ship's net load power value (> 10% PN for special ships). It constitutes an energy-economical alternative to electric operation with an adjustable propeller.

Claims (4)

1. Method for continuously supplying a ship's network from a frequency-variable propulsion network on a ship, where the propulsion network is fed by a propulsion generator operated by a primary energy converter with variable revolutions, where a propeller engine at revolutions below a minimum revolution number for the primary energy converter is connected to the propulsion network via a frequency converter and at a speed equal to or above the minimum speed directly in the form of an electric shaft, characterized in that at the minimum speed the propulsion network and the ship's network have the same frequency, that when the propeller motor (1) is operated at start-up with a speed below the minimum speed or with the minimum speed, the ship's mains and propulsion mains are directly connected to each other via a transformer (4) and a first switch (15), that when the propeller motor (1) has reached the minimum speed, the propeller motor (1) is switched on by means of another switch (10) ) - directly to the propulsion network and the frequency converter (5,6,7,8) by means of a switch (11) from the propeller motor (1), and that when the propeller motor (1) is operated at a speed above the minimum speed or when with another switch closed ( 10) and connected transformer (4) must perform a reversing or emergency stop maneuver, the frequency converter (5,6,7,8) is connected via a third switch (13) to the ship's mains and the first switch (15) is opened and a synchronous compensator (12) is connected in. 2. Method according to the introduction of claim 1, characterized in that at the minimum speed and when the propeller engine (1) is operated at a speed when starting below the minimum speed or with the minimum speed, the ship's mains is connected with a generator connected to the propulsion generator (3) (9) over a switch (14), that when the propeller motor (1) has reached the minimum number of revolutions, the propeller motor (1) is connected by means of another switch (10) directly to the propulsion network and the frequency converter (5,6,7,8) by means of a switch (11) is disconnected from the propeller motor (1) and that when the propeller motor (1) is operated with a speed above the minimum speed or when the other switch (10) is closed and a reversal or emergency stop maneuver must be carried out with it to the ship's mains connected generator (9), the frequency converter (5,6,7,8) is connected via a third switch (13) to the ship's mains and the first switch (15) is opened and a synchronous compensator (12) is connected to s the kipsnet. 3. Method according to claim 1 or 2, characterized in that when the propeller motor (1) is run up to the minimum number of revolutions, the current in the direct current intermediate circuit is limited via a rectifier (5) in the frequency converter (5,6,7,8) to keep the speed of the primary energy converter (2) constant. 4. Method according to one of claims 1-3, characterized in that the synchronous compensator (12) is driven up above the frequency converter (5,6,7,8) and connected together with the frequency converter (5,6,7,8) to the ship's mains.