Energy storage system of a watercraft

Abstract

The invention relates to an energy storage system (100) for at least one electrical consumer (106) in the onboard network (142) of a marine vessel (108), where the energy storage system (100) has at least one converter (140) connected to the onboard network (142) to supply power to the consumer (106). According to the invention, at least one energy storage (160) is allocated to one converter (140). Thus, consumers (106) that cause high electrical load peaks, such as a stabilization device (120), a rudder assembly (128) or the like, can be operated without problems in the onboard network (142) of a marine vessel (108).

Description

[0001] The invention relates to an energy storage system for at least one electrical consumer in an on-board network of a watercraft, wherein the energy storage system has at least one converter connected to the on-board network for supplying the consumer.

[0002] Fin stabilizers and rowing machines for passenger ships, larger yachts, floating pontoons, and similar vessels are known in a wide variety of designs. These fin stabilizers and rowing machines operate cyclically, with periods of high load peaks occurring due to rapid movements, often followed by periods of rest or standby with minimal energy consumption. These high load peaks necessitate a significantly over-dimensioned design for the drive train of the fin stabilizers, the rowing machines, and the onboard electrical system supplying these components.

[0003] Fin stabilizers and rowing machines are typically electro-hydraulically operated. In the case of an electro-hydraulic drivetrain, energy storage is only possible if a hydrostatic transmission is used as a so-called open hydraulic circuit with nitrogen accumulator support. A major disadvantage of this storage technology is the comparatively poor efficiency of an open hydraulic circuit, as unused energy must be dissipated as heat in the form of resistance control. While a closed hydraulic circuit for both speed-controlled and displacement-controlled systems exhibits a comparatively high efficiency, it cannot, by its very nature, utilize a hydraulic accumulator.

[0004] A supply system for a drillship is known from US 2017 / 298721 A1. Further technological background is disclosed in WO 2007 / 124968 A1, CN 110 304 228 A, US 2012 / 028516 A1 and US 2007 / 077830 A1.

[0005] One object of the invention is to provide an energy storage system for the on-board electrical system of a watercraft such as a ship, so that consumers causing high electrical load peaks can be operated without impairing the stability of the on-board electrical system.

[0006] The aforementioned problem is solved by an energy storage system according to claim 1. In particular, the at least one consumer is a stabilization device of the watercraft or a steering system for influencing the course of the watercraft, i.e., an electrical consumer that causes high peak loads, and an energy storage device is assigned to the at least one inverter. The energy storage device allows for virtually instantaneous retrieval of electrical energy required during peak load operation of the consumer, while simultaneously offering the option of recharging the storage unit during standby or idle phases of the consumer, in which it places little or no load on the watercraft's electrical system. Furthermore, the storage capacity of the energy storage device can be dimensioned so large that even in the event of a total electrical system failure (see above), sufficient energy can be supplied.The inverter (also known as a "black ship") ensures that the connected electrical device retains emergency functionality for at least a few minutes. This allows, for example, a fin of a stabilizing device to be moved to a rest position and mechanically locked. Furthermore, the rudder position of a rudder driven by a servo motor can be returned to neutral, or the rudder can be fully repositioned. The inverter can be configured in either block or segmented form. In particular, it allows large electrical consumers on a vessel that generate high, isolated load peaks to be decoupled from the ship's electrical system.

[0007] The energy storage device is connected to a DC link of the inverter. This allows for a simple integration of the energy storage device from a control engineering perspective.

[0008] In a technically advantageous design, the energy storage system comprises at least one energy converter and at least one associated storage unit. This allows for a modular and easily scalable design of the energy storage system.

[0009] Preferably, the energy converter is designed to enable bidirectional energy flow. As a result, a reversal of the energy flow is possible, or excess electrical energy can be fed back into the vessel's electrical system with minimal loss.

[0010] In the case of a technically advantageous further development, at least one storage unit is formed with at least one high-capacitance capacitor. This results in a high energy density of the storage unit with low maintenance requirements. Furthermore, capacitors exhibit high cycle stability, short response times, and a long service life. Examples of high-capacitance capacitors include ultracapacitors, supercapacitors, and double-layer capacitors. Alternatively or additionally, coils with the highest possible inductance can also be used.

[0011] In an advantageous embodiment, the at least one storage unit is formed with at least one flywheel system, in particular a flywheel or the like. Such storage units with a flywheel system achieve short response times, exhibit negligible self-discharge in the short term, and are insensitive to repeated deep discharges. Furthermore, a high energy density can be achieved with flywheel systems, for example, in the form of a flywheel rotating at a high speed of up to 100,000 revolutions per minute with a high mass. In addition, a stabilizing effect can optionally be achieved for a ship equipped in this way due to gyroscopic effects.

[0012] Preferably, the watercraft is a ship. This makes the invention applicable to the most common type of watercraft with a compact, elongated hull. Alternatively, the watercraft can also be a floating platform, a pontoon, an arrangement of pontoons, or the like.

[0013] A preferred embodiment of the invention is explained in more detail below with reference to schematic figures. The only Figure 1 shows a schematic block diagram of an energy storage system according to the invention for a watercraft.

[0014] Figure 1Figure 100 illustrates a schematic block diagram of an energy storage system according to the invention for a watercraft such as a ship. An energy storage system 100 serves, by way of example, to supply a large electrical consumer 106 of a watercraft 108, such as a ship 110 or the like, which causes high electrical load peaks. The electrical consumer 106 is shown here only by way of example as a stabilizing device 120 with at least one associated electric drive unit 122 for pivoting a stabilizing fin 126 – as indicated by a black double arrow 124 – to stabilize the ship 110 (not shown in detail) about at least one axis of space. Furthermore, the electrical consumer 106 can also be designed as a rudder system 128 with at least one steering motor 130 for driving at least one associated rudder 132 to influence the course of the ship 110.

[0015] The energy storage system 100 includes, among other things, a converter 140, which is supplied by the ship's electrical system 142 110. The electrical system 142 is preferably a three-phase AC network (not shown in detail in the drawing) with a neutral conductor and a protective conductor or earth. The converter 140 is shown here only as an example of a conventional converter with a passive diode bridge 146 for rectifying the three-phase AC 144 supplied by the electrical system 142, a DC link 148 for stabilization, and an output inverter 152. The output inverter 152 can be implemented with a variety of circuit breakers, of which only one, circuit breaker 150, is shown here as representative of all the other circuit breakers. The power switches can be, for example, power bipolar transistors, power MOSFETs, IGBTs, thyristors, triacs, etc.The inverter 140 supplies the electrical (large) load 106 with the necessary electrical energy via a supply line 154. The detailed circuit design of the inverter 140 is sufficiently familiar to a person skilled in the field of electrical power engineering, so that a detailed explanation can be omitted here for the sake of brevity and conciseness. Instead of three-phase alternating current 144, the vehicle electrical system 142 can also provide direct current, so that a voltage converter (not shown) or a so-called DC-DC converter is required instead of the (frequency) inverter 140.

[0016] The energy storage system 100 further comprises an energy storage device 160. The energy storage device 160 includes an energy converter 162, which is electrically connected to the inverter 140 via a connecting line 164. In addition, the energy storage device 160 has at least one associated storage unit 170 for storing different forms of energy, such as electrical energy, kinetic energy, chemical energy, or potential energy. Preferably, the energy storage device 160 is designed for low-loss storage of electrical energy.

[0017] The storage unit 170, not shown in detail in the drawing, could, for example, consist of a large number of high-capacitance (individual) capacitors connected together to form a capacitor bank. Of the individual capacitors in the capacitor bank, only one capacitor is shown as representative of all the others, designated by the reference numeral 172.

[0018] To enable the lossless feeding of energy stored in the storage unit 170 back into the DC link 148 of the converter 140, the energy converter 162 is designed to implement a bidirectional energy flow. For this purpose, the energy converter 162 can, for example, include at least one electrical converter or inverter (not shown in the drawing). If capacitors 172 are used to store electrical energy in the storage unit 170, the energy converter 162 is preferably implemented with a DC / DC converter. If, on the other hand, a flywheel or the flywheel 174 is used within the storage unit 170, the energy converter 162 is designed with an inverter. These circuit variants of the energy converter 162 allow the aforementioned bidirectional electrical energy flow.

[0019] Unlike a passive diode bridge, an active front-end module enables low-loss, bidirectional flow of electrical energy within the electrical converter in four-quadrant operation and can be implemented, for example, with actively switchable electronic switches such as IGBTs, power bipolar transistors, or power MOSFETs. A heating resistor for dissipating the returned electrical energy, which is still mandatory in electrical converters or inverters with a diode bridge, is eliminated. However, controlling an active front-end module is comparatively complex. If feedback from the inverter 140 into the vehicle electrical system 142 is to be possible, the diode bridge 146 in the inverter 140 must also be replaced by such an active front-end module.The detailed construction of such a converter with an active front-end module is sufficiently familiar to a specialist working in the field of power electronics, so that a more detailed explanation of the circuit technical details will be omitted here for the sake of brevity.

[0020] Alternatively or additionally, the storage unit 170 can include at least one flywheel system, such as a high-speed rotating flywheel 174. Furthermore, the storage unit 170 can include chemical accumulators with the highest possible energy density, such as lithium-ion or lithium-polymer accumulators. Optionally, the energy converter 162 can additionally or alternatively include at least one electrolysis cell and at least one fuel cell for converting electrical energy into chemical energy and vice versa. In this case, the storage unit 170 can, for example, be formed with a low-pressure metal hydride storage system or with a pressure accumulator for hydrogen at higher pressure, in order to be able to permanently store at least the hydrogen released by the electrolysis cell.

[0021] Energy can be supplied to the storage unit 170 of the energy storage system 160 by means of the energy converter 162. This energy is obtained by converting the electrical energy, which can be tapped from the DC link 148 of the inverter 140 via the connecting line 164, into an energy form suitable for the storage unit 170 by means of the energy converter 162. Conversely, energy can be drawn from the storage unit 170 and, by means of reconversion by the energy converter 162, supplied back to the DC link 148 of the inverter 140 in the form of electrical energy via the connecting line 164. This bidirectional process is illustrated by a charging arrow 180 and a discharging arrow 182 pointing in the opposite direction. The charging of the storage unit 170 with a suitable energy form generally continues until the storage unit 170 is fully charged.

[0022] If, for example, energy is stored within the storage unit 170 using the flywheel 174, the kinetic energy stored therein can be converted back into electrical energy using the energy converter 162 and fed back to the DC link 148 of the inverter 140 via the connecting line 164. This can be done, for example, using an electric motor operating in generator mode or a generator, which in such a configuration are preferably integrated into the energy converter 162 and are mechanically rotated by means of the flywheel 174. Conversely, electrical energy from the DC link 148 of the inverter 140 can be converted into kinetic energy using the energy converter 162 by, for example, driving the flywheel 174 with the help of the electric motor until a predetermined maximum speed of the flywheel 174 is reached.

[0023] If, however, high-capacity capacitors are used in the storage unit 170, for example, the energy converter 162 merely adjusts the supplied or discharged electrical energy with respect to the current and / or voltage. Furthermore, the energy converter 162 allows for modeling the time-dependent behavior of the current and / or voltage. If necessary, the energy converter 162 can also perform AC-DC conversion or vice versa, as well as DC-DC conversion.

[0024] In normal or standby operation of the electrical (large) consumer 106, available but currently unused electrical energy from the DC link 148 is preferably transferred to the energy storage device 160 via the connecting line 164, as illustrated by a storage arrow 190. This storage process generally continues until the energy storage device 160 is fully charged. Additionally, braking energy released by the electrical (large) consumer 106 can be stored in the energy storage device 160 (recuperation).

[0025] If, however, the electrical consumer 106 causes an electrical load peak or a high continuous load in the DC link 148 that cannot be fully or temporarily covered by the vehicle electrical system 142, the missing electrical energy is immediately fed back into the DC link 148 of the inverter 140 of the energy storage system 100 via the energy storage device 160 and the connecting line 164, as indicated by a backfeed arrow 192. This process can last up to several minutes, depending on the capacity of the storage unit 170 of the energy storage device 160. Consequently, short-term and even longer-term electrical overload conditions caused by the electrical (large) consumer 106 in the DC link 148 can be compensated for by means of the energy storage device 160.

[0026] Furthermore, due to the energy storage system 100 according to the invention, it is no longer necessary to design the electrical system 142 of the watercraft 108 for potentially infrequent maximum electrical load peaks of the electrical consumer 106. Moreover, in the event of a total failure of the electrical system 142 ("black ship"), at least emergency operation of the electrical consumer 106 is possible. For example, the stabilizing fin 126 of the stabilizing device 120 can be moved to a rest position and, if necessary, mechanically locked, using the electric drive unit 122, which in this configuration is supplied with emergency power by the energy storage device 160. The same applies to the electric steering motor 130 of the rudder unit 128 for driving the rudder 132.

[0027] All processes within the energy storage system 100, in particular the storage and restoration of electrical energy in or from the storage unit 170 via the energy converter 162, as well as the charging and discharging of the storage unit 170 of the energy storage system 160 with different forms of energy, in particular in the form of electrical energy, kinetic energy, potential energy and / or chemical energy using the energy converter 162, are controlled by a high-performance electronic control and / or regulation unit 200.

[0028] The invention relates to an energy storage system 100 for at least one electrical consumer 106 in the onboard electrical system 142 of a watercraft 108, wherein the energy storage system 100 comprises at least one inverter 140 connected to the onboard electrical system 142 for supplying power to the consumer 106. According to the invention, an energy storage device 160 is associated with the at least one inverter 140. This allows even consumers 106 that generate high electrical load peaks, such as a stabilization device 120, a rudder system 128, or the like, to be operated without difficulty on the onboard electrical system 142 of a watercraft 108. Reference symbol list

[0029] 100 Energy storage system 106 Electrical consumer 108 Watercraft 110 Ship 120 Stabilizing device 122 Electric drive unit 124 Black double arrow 126 Stabilizing fin 128 Rudder system 130 Electric steering machine 132 Rudder 140 Inverter 142 On-board power supply 144 Three-phase current 146 Diode bridge 148 DC intermediate circuit 150 Circuit breaker 152 Output inverter 154 Supply line 160 Energy storage 162 Energy converter 164 Connecting line 170 Storage unit 172 Capacitor 174 Flywheel 180 Charging arrow 182 Discharging arrow 190 Storage arrow 192 Regeneration arrow 200 Control and / or regulating unit

Claims

1. Energy storage system (100) for at least one electrical load (106) in an on-board electrical system (142) of a watercraft (108), wherein the energy storage system (100) comprises at least one converter (140), connected to the on-board electrical system (142), for supplying power to the load (106), wherein the at least one converter (140) has an energy store (160) assigned to it, wherein the at least one load (106) is a stabilizing device (120) of the watercraft (108) or a rudder system (128) for influencing the course of the watercraft (108), characterized in that the energy store (160) is connected to a DC link (148) of the converter (140).

2. Energy storage system (100) according to Claim 1, characterized in that the energy store (160) comprises at least one energy converter (162) and at least one storage unit (170) assigned to the latter.

3. Energy storage system (100) according to Claim 1 or 2, characterized in that the energy converter (162) is designed to enable a bidirectional energy flow.

4. Energy storage system (100) according to one of Claims 1 to 3, characterized in that the at least one storage unit (170) is formed by at least one high-capacity capacitor (172).

5. Energy storage system (100) according to one of Claims 1 to 3, characterized in that the at least one storage unit (170) is formed by at least one rotating mass system, in particular a flywheel (174) or the like.

6. Energy storage system (100) according to one of Claims 1 to 5, characterized in that the watercraft (108) is preferably a ship (110).