Energy storage hybrid power system of cable laying ship

Abstract

The invention relates to the technical field of power distribution circuits, in particular to an energy storage hybrid power system of a cable laying ship. Comprising a medium-voltage distribution board, the medium-voltage distribution board is connected with a first alternating-current motor through a first frequency converter, connected with a second alternating-current motor through a second frequency converter, connected with a lithium iron phosphate battery pack through a third frequency converter, and further connected with an alternating-current generator. Wherein the first frequency converter and the second frequency converter are conventional DFE frequency converters, and the third frequency converter comprises a transformer and an alternating current / direct current converter which are connected in sequence and is used for converting alternating current of the alternating current generator into direct current capable of charging the lithium iron phosphate battery pack and transmitting electric energy output by the battery pack to a system circuit through the transformer. By adding the battery pack, the service life loss caused by overload operation of the generator due to insufficient power supply in the system circuit can be prevented, and meanwhile, redundant electric energy in the system circuit is recycled for subsequent reutilization.

Description

Technical Field

[0001] The present invention relates to the technical field of power distribution circuits, and in particular to an energy storage hybrid power system for a cable-laying vessel. Background Art

[0002] During the operation of the cable-laying vessel, changes in the operating sea conditions cause the propulsion load to change at any time. In extreme cases, the frequency of the power grid changes is high and the fluctuations are large, which causes changes in the power demand of the propulsion system and has a negative impact on the quality of the entire ship's power grid. When the thruster accelerates or resists severe sea conditions, the generator set cannot provide the expected propulsion power demand due to the response lag, and the expected propulsion power is likely to exceed the design capacity of the ship's power grid. The rapid decrease in busbar voltage and the violent fluctuations in the main parameters of the ship's power grid will affect the safety of the cable-laying vessel during operation and the effectiveness of the operation. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides the following technical solutions: A cable-laying ship energy storage hybrid power system includes a medium-voltage distribution board. The medium-voltage distribution board is connected to a first AC motor through a first inverter, to a second AC motor through a second inverter, to a battery pack through a third inverter, and to an AC generator.

[0004] The first frequency converter and the second frequency converter both include an AC / DC converter and a DC / AC converter which are connected in sequence.

[0005] The third frequency converter includes a transformer and an AC / DC converter connected in sequence.

[0006] Preferably, a DC filter is further provided between the DC / DC converter and the third AC motor.

[0007] Preferably, a phase-shifting transformer is further provided between the DC / AC converter in the first frequency converter and the first AC motor, and the first AC motor is a full-rotation motor.

[0008] Preferably, the third frequency converter is connected to the third motor, a fourth frequency converter is provided between the third frequency converter and the third motor, and the fourth frequency converter is connected in parallel with the battery pack.

[0009] Preferably, the fourth frequency converter is a DC / AC converter.

[0010] Preferably, the generator, the first frequency converter, the second frequency converter and the third frequency converter are all connected in parallel to the medium voltage distribution board via a vacuum circuit breaker.

[0011] Preferably, the battery pack is a lithium iron phosphate battery pack.

[0012] A cable-laying vessel energy storage hybrid power energy-saving control method, applicable to the cable-laying vessel energy storage hybrid power system, comprises the following steps: S1. Real-time monitoring of the power load of the medium voltage distribution board.

[0013] S2. When the power load in the medium voltage distribution board exceeds the power supply load, control the battery pack to output power until the battery pack runs out of power and an alarm is sounded, or the power load in the medium voltage distribution board is equal to the power supply load and the battery pack output is stopped, then return to step S1; when the power load in the medium voltage distribution board is less than the power supply load, control the medium voltage distribution board to charge the battery pack until the battery is full and an alarm is sounded, or the power load in the medium voltage distribution board is equal to the power supply load and the battery pack is stopped from being charged, then return to step S1.

[0014] Compared with the prior art, the present invention has the following beneficial effects: by introducing a lithium iron phosphate battery pack, when the power load of the system circuit is less than the power supply load, the medium voltage distribution board is controlled to charge the battery pack so that the excess electric energy can be recovered. In particular, when the power load and the power supply load are stable, when the power load is less than the power supply load, there may be extra electric energy exceeding the power supply load. At this time, recycling the electric energy through the battery pack can also protect the safety of the system circuit. When the power load of the system circuit exceeds the power supply load, that is, when the electric energy is insufficient, the insufficient electric energy can be supplemented by the output of the battery pack, so that the recovered electric energy can be reused.

[0015] Other advantages, objectives and features of the present invention will be set forth in part in the following description and, in part, will be apparent to those skilled in the art based on an examination of the following or may be taught from the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the circuit structure of the system of the present invention; Figure numerals: 1. medium voltage distribution board; 2. AC generator; 3. first frequency converter; 4. first AC motor; 5. second frequency converter; 6. second AC motor; 7. third frequency converter; 8. battery pack; 9. third AC motor. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] See also Figure 1The present invention provides a cable-laying vessel energy storage hybrid power system, including a medium-voltage distribution board. The medium-voltage distribution board is connected to a first AC motor through a first frequency converter, a second AC motor through a second frequency converter, and a battery pack through a third frequency converter, and the medium-voltage distribution board is also connected to an AC generator. The AC generator generates electricity to provide power to the first AC motor and the second AC motor, and charges the battery pack.

[0019] The first frequency converter and the second frequency converter are both standard DFE frequency converters, including an AC / DC converter and a DC / AC converter connected in sequence from the medium voltage distribution board to the direction of the first AC motor or the second AC motor, and are used to adjust the speed and torque of the first AC motor and the second AC motor. The third frequency converter includes a transformer and an AC / DC converter connected in sequence from the medium voltage distribution board to the battery pack. The AC / DC converter converts the AC power generated by the generator into DC power, which is used to charge the battery pack with DC power. In this embodiment, the battery pack is a lithium iron phosphate battery pack, which can only be charged with DC power. The transformer is used to transform the electric energy output by the battery to facilitate the transmission of the electric energy output by the battery pack in the circuit. Since the transformer can only be used for AC power, the AC / DC converter is between the transformer and the battery pack. Therefore, when the cable-laying ship is sailing, when the electric power output by the AC generator is lower than the load power of the circuit system, the battery pack can be used to supplement the remaining insufficient electric power; when the electric power output by the AC generator is higher than the load power of the circuit system, the excess power can be used to charge the battery pack, so that the battery pack can play the role of peak shaving and valley filling, thereby minimizing the fuel consumption of the ship and improving the economy of the ship.

[0020] A DC / DC converter is also provided between the third inverter and the battery pack to adjust the voltage of the DC power to the voltage range for battery charging.

[0021] A DC filter is also provided between the DC / DC converter and the third AC motor for smoothing the DC power output by the DC / DC converter and providing the battery pack with stable DC power for charging.

[0022] A phase-shifting transformer is also provided between the DC / AC converter in the first frequency converter and the first AC motor, and the first AC motor is a full-rotation motor. When the cable-laying vessel decelerates and brakes, the first AC generator takes on the role of providing reverse power, and then reverses to generate AC power, which is convenient to transmit by adding a phase-shifting transformer.

[0023] The third inverter is also connected to a third AC motor, and a fourth inverter is provided between the third inverter and the third AC motor, and the fourth inverter is connected in parallel with the battery pack. The fourth inverter is a DC / AC converter, which is used to convert the DC power output by the third inverter into AC power that can drive the third AC motor. In addition, the DC power output by the battery pack can also be directly converted into AC power by the fourth inverter and then directly drive the third AC motor.

[0024] The generator, the first frequency converter, the second frequency converter and the third frequency converter are all connected in parallel to the medium voltage switchboard through the vacuum circuit breaker, so as to precisely control each component connected to the medium voltage switchboard.

[0025] The control method of the cable-laying vessel energy storage hybrid power system of the present invention comprises the following steps: S1. Monitor the power load of the medium voltage switchboard in real time through the control system. The power load in the system circuit can be monitored by setting corresponding sensors in the medium voltage switchboard; corresponding sensors can also be set in the AC generator, the first AC motor, the second AC motor and the third AC motor to monitor the power load of each component in the system, and each sensor is connected to the control system of the cable-laying vessel for real-time monitoring.

[0026] S2. When the power load in the medium voltage distribution board exceeds the power supply load, the battery pack is controlled to output power until the power of the battery pack is exhausted and an alarm is issued, or the power load in the medium voltage distribution board is equal to the power supply load and the battery pack output power is stopped, and then the process returns to step S1. The power in the system is supplemented by the power output of the battery pack, so that the AC generator is always in the set optimal compliance rate, avoiding overload operation of the AC generator due to sudden high load, saving fuel consumption and increasing the service life of the AC generator.

[0027] When the power load in the medium voltage distribution board is less than the power supply load, the medium voltage distribution board is controlled to charge the battery pack until the battery is full and an alarm is issued or the power load in the medium voltage distribution board is equal to the power supply load, and the battery pack is stopped from being charged, and then the execution of step S1 is returned. A typical situation is that the AC generator cannot provide the overdue propulsion power demand due to the response lag, and the expected propulsion power is likely to exceed the design capacity of the system power grid. The rapid reduction of the system circuit voltage and the violent fluctuation of the main parameters of the system circuit will affect the safety of the system circuit, and thus affect the actual operation of the cable laying ship; for example, when the first AC motor rotates during deceleration, the first AC motor is equivalent to an AC generator, which will feed back a part of the electric energy to the system circuit, causing the system circuit voltage to increase, affecting the safety of the system circuit. By charging the battery pack to store the excess electric energy in the circuit, the safety of the system circuit can be guaranteed, and it can be released when needed to achieve energy recovery and reuse.

[0028] On the basis of the above implementation scheme, the processors, modules, corresponding control programs, algorithm programs and other supporting technologies mentioned in the present invention can be implemented in combination with existing electrical technology, information technology, software technology and general protocols. They are not within the scope of protection required by the present invention and will not be described in detail in this application.

[0029] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered as exemplary and non-restrictive in all respects.

Claims

1. A cable-laying vessel energy storage hybrid power system, comprising a medium voltage switchboard, characterized in that: The medium voltage distribution board is connected to a first AC motor via a first frequency converter, is connected to a second AC motor via a second frequency converter, is connected to a battery pack via a third frequency converter, and is connected to an AC generator; The first frequency converter and the second frequency converter each include an AC / DC converter and a DC / AC converter connected in sequence; The third frequency converter includes a transformer and an AC / DC converter which are connected in sequence.

2. The cable-laying vessel energy storage hybrid power system according to claim 1, characterized in that: A DC / DC converter is also provided between the third frequency converter and the battery pack.

3. The cable-laying vessel energy storage hybrid power system according to claim 2, characterized in that: A DC filter is also provided between the DC / DC converter and the third AC motor.

4. The cable-laying vessel energy storage hybrid power system according to claim 1, characterized in that: A phase-shifting transformer is also provided between the DC / AC converter in the first frequency converter and the first AC motor, and the first AC motor is a full-rotation motor.

5. The cable-laying vessel energy storage hybrid power system according to claim 1, characterized in that: The third frequency converter is also connected to a third motor, a fourth frequency converter is arranged between the third frequency converter and the third motor, and the fourth frequency converter is connected in parallel with the battery pack.

6. The cable-laying vessel energy storage hybrid power system according to claim 1, characterized in that: The fourth frequency converter is a DC / AC converter.

7. The cable-laying vessel energy storage hybrid power system according to claim 1, characterized in that: The generator, the first frequency converter, the second frequency converter and the third frequency converter are all connected in parallel to the medium voltage distribution board via a vacuum circuit breaker.

8. The cable-laying vessel energy storage hybrid power system according to claim 1, characterized in that: The battery pack is a lithium iron phosphate battery pack.

9. A cable-laying vessel energy storage hybrid power energy-saving control method, using the cable-laying vessel energy storage hybrid power system as claimed in any one of claims 1 to 8, characterized in that: Includes steps: S1. Real-time monitoring of the power load of the medium voltage distribution board through the control system; S2. When the power load in the medium-voltage distribution board exceeds the power supply load, the battery pack is controlled to output electric energy until the power of the battery pack is exhausted and the power load in the medium-voltage distribution board is equal to the power supply load, and the battery pack output is stopped, and then the process returns to step S1; when the power load in the medium-voltage distribution board is less than the power supply load, the medium-voltage distribution board is controlled to charge the battery pack until the battery is fully charged or the power load in the medium-voltage distribution board is equal to the power supply load, and then the process returns to step S1.

10. The cable-laying vessel energy storage hybrid power energy-saving control method according to claim 9, characterized in that: In the step S2, the control system issues an alarm when the power of the battery pack is exhausted or the power of the battery pack is fully charged.

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