Energy management system of marine lifeboat collecting and releasing device

Abstract

The invention discloses an energy management system of a marine lifeboat collecting and releasing device. The energy management system comprises a four-quadrant frequency converter, a super capacitor energy storage system and an energy path control module, the four-quadrant frequency converter is connected with a ship alternating current power supply and a servo motor; the direct current bus is connected with the braking unit, the braking resistor and the DC / DC bidirectional converter; the super capacitor is connected with the direct current bus through the DC / DC bidirectional converter; the energy path control module dynamically controls an energy path by monitoring the voltage and the charge state of the super capacitor in real time; through cooperative control of the four-quadrant frequency converter and the super-capacitor energy storage system, a three-level redundancy mechanism of energy storage buffering, power grid feedback and resistance energy consumption is formed, multi-level efficient utilization of regenerated energy is achieved, the energy utilization rate is increased, the problem that an existing device cannot achieve emergency recovery under the sudden power loss working condition is solved, and the energy utilization rate is increased. And the reliability and the environmental protection property of the system are obviously improved.

Description

Technical Field

[0001] The invention relates to marine hoisting equipment, in particular to an energy management system for a marine lifeboat retrieval and launching device. Background Art

[0002] As an important part of the ship's hoisting equipment, the ship's lifeboat launching and retrieving device is mainly used for the rapid release and recovery of lifeboats in emergency situations. Its driving mode is mainly electric drive. In the prior art, the electric drive mode realizes partial energy recovery and utilization by feeding back the regenerative energy generated by the motor to the ship's power grid. However, this energy management mode mainly revolves around the two dimensions of immediate consumption and power grid feedback, and has obvious limitations: first, when the ship suddenly loses power or encounters a generator failure, due to the lack of an effective energy storage unit, the system cannot call on the reserved emergency energy to support the operation of the equipment, resulting in the instantaneous loss of power and emergency response capabilities of the ship's lifeboat launching and retrieving device; secondly, the energy feedback mechanism of the existing device depends on the stability of the ship's power grid. When the power grid capacity is insufficient or fluctuates greatly, the regenerative energy cannot be effectively fed back and can only be consumed in the form of heat energy through the braking resistor, resulting in energy waste. Summary of the invention

[0003] Purpose of the invention: The purpose of the present invention is to provide an energy management system for a marine lifeboat launching and retracting device which can realize multi-level efficient utilization of regenerated energy and meet the requirements of emergency release and recovery of lifeboats.

[0004] Technical solution: The energy management system of the marine lifeboat launching and retracting device of the present invention comprises an electric winch, a servo motor and a PLC controller. The system also comprises a four-quadrant frequency converter, a supercapacitor energy storage system and an energy path control module; the three-phase AC input end of the four-quadrant frequency converter is connected to the ship's AC power supply, the output end is connected to the servo motor, and its DC bus is connected to the braking unit, the braking resistor and the DC / DC bidirectional converter; the supercapacitor energy storage system is connected to the DC bus of the four-quadrant frequency converter through a DC / DC bidirectional converter; the energy path control module is integrated in the PLC controller, and is used to monitor the voltage U_ca and the state of charge SOC of the supercapacitor in real time, and dynamically control the energy path according to the servo motor state and the SOC value:

[0005] (a) When the servo motor is in the power generation state and the SOC is less than 100%, the DC / DC bidirectional converter is activated to charge the supercapacitor;

[0006] (b) When SOC=100%, the four-quadrant inverter power feeding function is switched to feed energy back to the ship's power grid; after being fed back to the ship's power grid, the excess regenerative energy is consumed by the braking unit and the braking resistor;

[0007] (c) When the ship loses power, the supercapacitor boosts the voltage through the DC / DC bidirectional converter to power the servo motor and PLC controller.

[0008] Preferably, the state of the servo motor is determined by the rotation speed n detected by the encoder and the torque T detected by the pressure sensor:

[0009] When n>0 and T>0, or n<0 and T<0, it is determined to be in electric state;

[0010] When n>0 and T<0, or n<0 and T>0, it is determined to be in the power generation state.

[0011] Preferably, the four-quadrant frequency converter adopts active front end (AFE) technology, including a pre-charging circuit, an LCL filter and an IGBT unit for realizing rectification and inversion functions and controlling activation and deactivation of a feeding function.

[0012] Preferably, the DC / DC bidirectional converter is a bidirectional Buck-Boost topology structure for bidirectional voltage conversion between the DC bus and the supercapacitor, performing step-down conversion when the supercapacitor is charged and performing step-up conversion during emergency power supply; its control end is connected to the PLC controller through a PWM signal to receive closed-loop control instructions for charging and discharging currents.

[0013] Preferably, the energy path control module communicates with the PLC controller via a CAN bus and adopts a CANopen protocol to transmit data.

[0014] Preferably, the rated voltage of the supercapacitor energy storage system is U_c, the maximum charging voltage is U_max, and U_max>U_c, ensuring that the supercapacitor operates within a safe voltage range.

[0015] Preferably, the rated power of the brake unit and the brake resistor matches the maximum regenerative power of the servo motor.

[0016] Preferably, the PLC controller receives the signal of the pressure sensor through an analog input channel, and controls the charging and discharging operation of the DC / DC bidirectional converter through a digital output channel.

[0017] Preferably, the delay time of the energy path switching is less than or equal to the dynamic response time of the four-quadrant inverter.

[0018] Preferably, the encoder is installed on an electric winch, and the pressure sensor is installed on a fixed pulley of a marine lifeboat launching and retracting device.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: through the coordinated control of the four-quadrant inverter and the supercapacitor energy storage system, a three-level redundant mechanism of "energy storage buffer, grid feedback, and resistance energy consumption" is formed, realizing multi-level efficient utilization of renewable energy, which not only improves the energy utilization rate, but also solves the problem that the existing device cannot be recovered in an emergency under sudden power failure conditions, and significantly improves the reliability and environmental protection of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0021] Figure 2 Schematic diagram of the control mode of the servo motor of the present invention.

[0022] Figure 3 The present invention is a flow chart of utilizing the energy recovery system to recover and utilize load potential energy.

[0023] Figure 4 It is the simulink simulation model diagram of the present invention.

[0024] Figure 5 This is a diagram of the torque variation of the servo motor when the system of the present invention performs energy recovery.

[0025] Figure 6 This is a diagram showing the change in speed of the servo motor when the system of the present invention performs energy recovery.

[0026] Figure 7 This is a diagram of supercapacitor voltage changes when the system of the present invention performs energy recovery.

[0027] Figure 8 This is a diagram of supercapacitor current changes when the system of the present invention performs energy recovery.

[0028] Fig. 9 This is a diagram showing the change in supercapacitor voltage when releasing energy according to the present invention.

[0029] Fig.10 This is a diagram showing the change in supercapacitor current when releasing energy according to the present invention.

[0030] Fig.11 The invention discloses an energy recovery electrical system solution for a marine lifeboat launching and retracting device. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0032] like Figure 1-11As shown, a marine lifeboat launching and retracting device energy management system in this embodiment includes: a 380V AC power supply, a four-quadrant inverter, a servo motor, a DC / DC bidirectional converter, a supercapacitor energy storage system, an energy path control module, an encoder, a pressure sensor, a winch drum, a brake unit, a brake resistor and a PLC controller.

[0033] The overall connection relationship of the system is as follows: 380V AC power supply is connected to the three-phase AC power input terminal of the four-quadrant inverter, and connected to the IGBT unit through the pre-charging circuit and LCL filter; the three-phase output terminal of the four-quadrant inverter is connected to the servo motor, and the DC bus terminal is connected in parallel with the brake unit, brake resistor and DC / DC bidirectional converter input terminal; the output terminal of the DC / DC bidirectional converter is connected to the supercapacitor energy storage system, the supercapacitor has a rated voltage of U_c and a maximum charging voltage of U_max, and the voltage monitoring circuit is used to ensure that U_ca is less than or equal to U_max; the servo motor output shaft is mechanically coupled to the winch drum, and the encoder is installed on the winch. The end of the main shaft of the vehicle is used to detect the speed n in real time; the pressure sensor is installed on the fixed pulley bearing seat of the lifeboat hanging point, and a strain sensor is used to measure the wire rope tension and calculate the torque T; the PLC controller receives the pressure sensor signal through the analog input channel and collects the encoder pulse signal through the high-speed counter module; its digital output channel is connected to the enable end of the DC / DC bidirectional converter, and the charging and discharging current is adjusted through the PWM signal; the energy path control module is integrated into the PLC controller in the form of a software function block, and communicates with the four-quadrant inverter and DC / DC converter through the CAN bus using the CANopen protocol.

[0034] Among them, the four-quadrant inverter mainly adopts AFE technology, including pre-charging circuit, LCL filter and IGBT unit for realizing rectification and inversion functions and controlling the activation and shutdown of the feeding function. The active front end (AFE) device can meet the four-quadrant operation of the motor, and can work as a rectifier in the first and third quadrants, or as an inverter in the second and fourth quadrants. On the one hand, it rectifies the AC power on the grid side into stable DC power and supplies power to the connected motor module; on the other hand, it can also feed back the remaining energy on the DC bus to the grid when the voltage of the DC bus rises due to the regenerative energy of the motor transmission. The entire AFE device consists of two parts: the pre-charging circuit allows the IGBT unit to enter its working range through pre-charging; the LCL filter can filter the influence of the IGBT switching frequency; the IGBT unit provides power and regenerative power to the DC bus. In the electric state, the inverter converts AC power into DC power to drive the motor to operate; when the motor enters the power generation state due to the lowering of the lifeboat, the regenerative energy is fed back to the system through the DC bus. At this time, if the supercapacitor is not fully charged, the bidirectional DC / DC converter will step down the energy and store it in the supercapacitor; if the capacitor is full, it will switch to the grid feedback mode and send the excess energy back to the ship's grid. When the grid cannot absorb or there is a sudden power outage, the braking resistor will be immediately put into use to consume the excess energy in the form of heat energy to ensure the stability of the bus voltage.

[0035] The DC / DC bidirectional converter is responsible for the voltage conversion between the DC bus and the supercapacitor. On the one hand, the DC / DC bidirectional converter controls the voltage of the supercapacitor discharged to the DC bus, converts the output voltage of the supercapacitor into the DC bus line voltage, and the DC bus line voltage is inverted into an AC power supply machine through the IGBT on the motor side; on the other hand, the DC / DC bidirectional converter can also convert excess electrical energy into a charging voltage suitable for the supercapacitor to charge the supercapacitor. By controlling the output current of the DC / DC bidirectional converter during charging / discharging, energy can be stored or released from the DC bus.

[0036] The energy management strategy of the whole system is as follows: the core control logic of the system is implemented by the PLC controller, which integrates the energy path control module, communicates with the four-quadrant inverter and DC / DC converter through the CAN bus, monitors the voltage and charge state SOC of the supercapacitor in real time, and dynamically adjusts the energy path according to the servo motor state. When the encoder detects that the speed is opposite to the torque direction detected by the pressure sensor, it is determined that the servo motor is in the power generation state, and the PLC controller preferentially uses the supercapacitor to store energy. The charge state SOC and voltage of the supercapacitor are fed back in real time by the built-in monitoring module. If the SOC is lower than 100% and the voltage is within the safe range, the PLC controls the DC / DC bidirectional converter to charge the supercapacitor; when it is detected that the SOC reaches 100%, that is, the capacitor is full, the PLC controller automatically activates the grid feedback function of the four-quadrant inverter, and feeds back the excess regenerative energy to the ship's power grid. When the power grid cannot absorb it, the braking resistor is immediately put into use to consume excess energy in the form of heat energy to ensure the stability of the bus voltage. During this process, if the ship's power grid is detected to be out of power, the PLC controller immediately cuts off the connection between the four-quadrant inverter and the power grid, and controls the DC / DC converter to switch to boost mode, boosting the electric energy stored in the supercapacitor to the DC bus, providing emergency power for the servo motor and PLC controller, and ensuring that the lifeboat can still be retracted and deployed in an emergency. Through the coordinated control of the four-quadrant inverter and the supercapacitor energy storage system, a three-level redundant mechanism of "energy storage buffer, grid feedback, and resistor energy consumption" is formed, realizing multi-level efficient utilization of regenerated energy, which not only improves energy utilization, but also solves the problem that the existing device cannot be recycled in an emergency under sudden power outage conditions, significantly improving the reliability and environmental protection of the system.

Claims

1. An energy management system for a marine lifeboat launching and retracting device, comprising an electric winch, a servo motor and a PLC controller, characterized in that: The system also includes a four-quadrant frequency converter, a supercapacitor energy storage system and an energy path control module; the three-phase AC input end of the four-quadrant frequency converter is connected to the ship AC power supply, the output end is connected to the servo motor, and its DC bus is connected to the braking unit, the braking resistor and the DC / DC bidirectional converter; the supercapacitor energy storage system is connected to the DC bus of the four-quadrant frequency converter through a DC / DC bidirectional converter; the energy path control module is integrated in the PLC controller, which is used to monitor the voltage U_ca and the state of charge SOC of the supercapacitor in real time, and dynamically control the energy path according to the servo motor state and SOC value: (a) When the servo motor is in the power generation state and the SOC is less than 100%, the DC / DC bidirectional converter is activated to charge the supercapacitor; (b) When SOC=100%, the four-quadrant inverter power feeding function is switched to feed energy back to the ship's power grid; after being fed back to the ship's power grid, the excess regenerative energy is consumed by the braking unit and the braking resistor; (c) When the ship loses power, the supercapacitor boosts the voltage through the DC / DC bidirectional converter to power the servo motor and PLC controller.

2. The energy management system according to claim 1, characterized in that: The state of the servo motor is determined by the speed n detected by the encoder and the torque T detected by the pressure sensor: When n>0 and T>0, or n<0 and T<0, it is determined to be in electric state; When n>0 and T<0, or n<0 and T>0, it is determined to be in the power generation state.

3. The energy management system according to claim 1, characterized in that: The four-quadrant frequency converter adopts active front-end technology, including a pre-charging circuit, an LCL filter and an IGBT unit.

4. The energy management system according to claim 1, characterized in that: The DC / DC bidirectional converter is a bidirectional Buck-Boost topology structure.

5. The energy management system according to claim 1, characterized in that: The energy path control module communicates with the PLC controller via the CAN bus and uses the CANopen protocol to transmit data.

6. The energy management system according to claim 1, characterized in that: The rated voltage of the supercapacitor energy storage system is U_c, the maximum charging voltage is U_max, and U_max>U_c.

7. The energy management system according to claim 1, characterized in that: The rated powers of the brake unit and the brake resistor match the maximum regenerative power of the servo motor.

8. The energy management system according to claim 1, characterized in that: The PLC controller receives the signal of the pressure sensor through the analog input channel, and controls the charging and discharging operation of the DC / DC bidirectional converter through the digital output channel.

9. The energy management system according to claim 1, characterized in that: The delay time of the energy path switching is less than or equal to the dynamic response time of the four-quadrant frequency converter.

10. The energy management system according to claim 2, characterized in that: The encoder is installed on the electric winch, and the pressure sensor is installed on the fixed pulley of the marine lifeboat retrieval and launching device.

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