A gravity energy storage system for a container ship tractor based on an axle generator and a control method thereof
By constructing a gravity energy storage system for the traction machine on a container ship, the surplus electrical energy of the shaft-driven generator is converted into gravitational potential energy, achieving efficient storage and release of the main engine's energy. This solves the problem of mismatch between the main engine's surplus energy and the grid load, and improves energy utilization efficiency and system safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TONGJI UNIV
- Filing Date
- 2026-04-24
- Publication Date
- 2026-07-24
AI Technical Summary
Existing shaft-driven power generation systems struggle to match the surplus energy of the main engine with the real-time load of the ship's power grid, leading to energy waste and the use of high-cost auxiliary diesel generators. Furthermore, traditional energy storage devices have limited or complex capacities, making it difficult to achieve efficient and safe energy dispatch.
A gravity energy storage system based on a shaft-driven generator for container ship traction machines is constructed. The system converts surplus electrical energy into gravitational potential energy through the traction machine and container lifting device, and automatically switches between energy storage and release modes under real-time power demand changes. Combined with a closed-loop control strategy, the system ensures grid stability.
It improves the overall efficiency and economy of ship energy utilization, reduces the use of auxiliary diesel generators, enhances the engineering feasibility and operational safety of the system, and solves the problems of high cost and poor safety of energy storage equipment.
Smart Images
Figure CN122456574A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of shaft-driven power generation technology, and in particular to a gravity energy storage system for container ship traction machines based on a shaft-driven generator and its control method. Background Technology
[0002] Marine shaft generator systems have become standard equipment on ocean-going vessels to fully utilize the surplus energy generated during main engine operation. More importantly, this system can bring continuous and substantial economic returns to ship owners. Marine shaft generator technology utilizes the ship's main propulsion shaft to tow a generator to generate electricity. The shaft generator outputs stable three-phase AC power via a frequency converter and connects to the ship's electrical grid to power daily equipment. The shaft generator system can operate independently on the grid or be connected in long-term parallel operation with other diesel generator sets. When the main engine has significant surplus energy, the rated power of the shaft generator system often exceeds the ship's load power, resulting in wasted main engine energy. When the main engine's surplus energy is insufficient, auxiliary diesel generators need to be started to supplement the energy, increasing energy costs.
[0003] However, existing shaft generator systems present a significant technical contradiction: the surplus power of the main engine is difficult to match with the real-time load of the ship's power grid. When the main engine is operating at high power, the electrical energy generated by the shaft generator may far exceed the ship's immediate power demand. This excess energy, lacking effective storage methods, must be dissipated or restricted, resulting in a waste of the main engine's surplus energy. Conversely, when the main engine is operating at low speed or during peak ship power consumption, the output power of the shaft generator is insufficient, necessitating the activation of auxiliary diesel generator sets (usually fuel-fired generator sets) to supplement the power gap in the power grid. This not only increases expensive fuel consumption and carbon emissions but also introduces operating and maintenance costs and noise pollution from the auxiliary generators. For example, patent application CN121012126A discloses a hybrid power efficiency optimization system for shaft generators and energy storage under multiple operating conditions on container ships. This system identifies ship operating condition information through an operating condition strategy module, predicts sudden load changes in refrigerated containers and generates compensation requests through a fluctuation suppression module, and coordinates the output power of the main engine shaft generator, auxiliary generator, and hybrid energy storage device through a power allocation module, thereby achieving optimized power system scheduling. Although this method uses a composite energy storage device to absorb the excess energy of the host, it fails to resolve the fundamental contradiction between the limited energy storage capacity and the huge excess energy of the host. After the energy storage device is fully charged, the excess energy of the host will still be forced to dissipate. At the same time, this method focuses too much on the load prediction of the refrigerated container and ignores the sudden change risk of other high-power equipment. Furthermore, the geofence condition identification lacks coupling with real-time sea conditions, resulting in a weak correlation between condition judgment and power demand. Summary of the Invention
[0004] The purpose of this invention is to overcome the defects of the prior art by providing a gravity energy storage system for container ship traction machines based on a shaft-driven generator and its control method, thereby improving the comprehensive utilization efficiency, economy and environmental friendliness of ship energy.
[0005] The objective of this invention can be achieved through the following technical solutions: A gravity energy storage system for a container ship traction machine based on a shaft-driven generator includes a shaft-driven generator, an energy storage conversion device, a traction machine, and a container lifting device. The energy storage conversion device includes a shaft-driven generator frequency converter module, an energy storage traction machine frequency converter module, and a ship power grid side frequency converter module connected in parallel with the DC bus. The shaft-driven generator frequency converter module is connected to the shaft-driven generator and is used to convert the AC power output by the shaft-driven generator into electrical energy that meets the requirements of the ship power grid. The energy storage traction machine frequency converter module is connected to the traction machine and is used to drive and control the traction machine. The ship power grid side frequency converter module is connected to the ship power grid and is used to realize bidirectional energy flow between the DC bus and the ship power grid. The container lifting device is used to realize the lifting and lowering movement of containers under the drive of a traction machine; The excess electrical energy of the shaft-driven generator is converted into the gravitational potential energy of the container through the energy storage conversion device, traction machine and container lifting device. When the power demand of the ship's power grid is high, the energy is released to generate electricity, and the system automatically switches between gravity energy storage mode and gravity energy release mode according to real-time power comparison.
[0006] Furthermore, the shaft-driven generator is mounted on the propeller shaft connected to the ship's main engine.
[0007] Furthermore, the traction machine adopts a gearless permanent magnet synchronous motor, and its working state includes motoring state and generator state. When the available power of the shaft-driven generator is greater than the total load power of the ship's electrical grid, the traction machine is in motoring state, and when the available power of the shaft-driven generator is less than the total load power of the ship's electrical grid, the traction machine is in generator state.
[0008] Furthermore, the container lifting device includes a container spreader, a counterweight, a lifting guide rail, and a brake. The container spreader and the counterweight are connected to the traction machine via cables, and the brake is used to lock the container spreader and the counterweight when the traction machine is not in operation.
[0009] Furthermore, lifting guide shoes are provided on both sides of the container spreader and the counterweight, and the shoe lining inside is matched and connected with the lifting guide rail to fix the container spreader and the counterweight on the lifting guide rail.
[0010] According to another aspect of the present invention, a control method for a gravity energy storage system for a container ship traction machine based on a shaft-driven generator is provided, which switches the operating mode of the container ship traction machine gravity energy storage system based on a shaft-driven generator as described above, including the following steps: The system powers on and performs initialization checks. Start the ship's main engine, which drives the propeller shaft to rotate, thereby driving the shaft-driven generator to run; The available power of the shaft-driven generator is calculated in real time and compared with the total load power of the ship's electrical grid: When the available power of the shaft-driven generator is greater than the total load power of the ship's electrical grid, the auxiliary diesel generator stops working, the system enters the gravity energy storage mode, the traction machine is in electric state, and it detects whether the container meets the energy storage conditions. If the container meets the energy storage conditions, the excess electrical energy of the shaft-driven generator is converted into gravitational potential energy by the traction machine. If the container does not meet the energy storage conditions, the energy storage process ends. When the available power of the shaft-driven generator is less than the total load power of the ship's electrical grid, the system enters the gravity energy release mode, the traction machine is in the power generation state, and it detects whether the container meets the energy release conditions. If the container meets the energy release conditions, it performs a descent energy release operation to convert the stored gravitational potential energy back into electrical energy, which, together with the shaft-driven generator, supplies power to the ship's electrical grid. If the container does not meet the energy release conditions, the energy release process ends.
[0011] Furthermore, the energy storage condition is that there is room for improvement at the current height of the container, and the specific steps of the energy storage process include: Release the brakes on the container spreader and counterweight to drive the traction machine to lift the container; When the available power of the shaft-driven generator is greater than the sum of the total load power of the ship's electrical grid and the driving power of the traction machine, the traction machine is controlled to lift the container at a constant speed until the container no longer meets the energy storage conditions. The traction machine then stops working, and at the same time, the brakes of the container spreader and the counterweight are closed. The output power of the shaft-driven generator is adjusted to be the same as the total load power of the ship's electrical grid. When the available power of the shaft-driven generator is less than the sum of the total load power of the ship's electrical grid and the driving power of the traction machine, the traction machine stops working, the brakes of the container spreader and the counterweight are closed, and the output power of the shaft-driven generator is adjusted to be the same as the total load power of the ship's electrical grid.
[0012] Furthermore, the energy release condition is that there is room for the container to descend from its current height, and the specific steps of the energy release process include: Release the braking devices of the container spreader and counterweight, control the traction machine to lower the container, so as to drive the rotor of the traction machine to rotate and generate electricity; When the sum of the output power of the shaft-driven generator and the power generation of the traction machine is greater than the total load power of the ship's electrical network, the traction machine is controlled to lower the container at a constant speed until the container no longer meets the energy release condition. The traction machine then stops working, the brakes of the container spreader and the counterweight are closed, and the output power of the shaft-driven generator is adjusted to be the same as the total load power of the ship's electrical network. If the sum of the output power of the shaft-driven generator and the power generation of the traction machine is less than the total load power of the ship's electrical network, the traction machine stops working, the brakes of the container spreader and the counterweight are closed, and the output power of the shaft-driven generator is adjusted to be the same as the total load power of the ship's electrical network.
[0013] Furthermore, when the traction machine is in electric mode, the calculation formula for converting excess electrical energy from the shaft-driven generator into gravitational potential energy through the traction machine is as follows: In the formula, It is gravitational potential energy. This represents the available power of the shaft-driven generator. This represents the total load power of the ship's electrical network. This refers to the time it takes for the container to be lifted at a constant speed.
[0014] Furthermore, when the power of the ship's main engine is insufficient, the diesel auxiliary generator is started, all non-essential electrical loads on the ship are shut down, the brakes on the container spreader and counterweight are released, and the traction machine is controlled to lower the container according to power requirements.
[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention is based on a shaft-driven generator and constructs a gravity energy storage system consisting of a traction machine and a container lifting device. The surplus electrical energy of the shaft-driven generator is converted into the gravitational potential energy of the container for storage. When the power demand of the ship's power grid is high, the energy is released to generate electricity. The system automatically switches between gravity energy storage mode and gravity energy release mode based on real-time power comparison. This overcomes the limitation of existing technologies where the surplus power of the main engine is mismatched with the real-time load of the power grid, resulting in energy waste. It also solves the problem of ships relying on high-cost and high-pollution auxiliary diesel generators for power regulation, thereby improving the comprehensive utilization efficiency, economy, and environmental friendliness of ship energy.
[0016] 2. This invention deeply integrates gravity energy storage systems with the business structure of container ships by using containers as energy storage weights. It also adopts a closed-loop control strategy based on ensuring grid stability, overcoming the limitations of high cost, poor safety, and high modification difficulty associated with adding large chemical batteries or complex energy storage systems. This invention solves the engineering application problem of traditional solutions in achieving efficient, safe, and reliable energy storage and energy dispatch within limited space, thereby improving the system's engineering feasibility, operational safety, and long-term operational reliability. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the structure of a gravity energy storage system for a container ship traction machine based on a shaft-driven generator, as proposed in this invention. Figure 2 This is a schematic diagram of the electrical topology of the energy storage conversion device; Figure 3 This is a flowchart illustrating the control method for a gravity energy storage system for a container ship traction machine based on a shaft-driven generator, as proposed in this invention. Figure 4 This is a schematic diagram of the energy storage and release processes. Detailed Implementation
[0018] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.
[0019] The following English abbreviations are involved: Sinusoidal Pulse Width Modulation (SPWM) Insulated Gate Bipolar Transistor (IGBT) Example 1 This embodiment provides a gravity energy storage system for container ship traction machines based on a shaft-driven generator, such as... Figure 1 As shown, it includes a shaft-driven generator, an energy storage conversion device, a traction machine, and a container lifting device.
[0020] The excess electrical energy of the shaft-driven generator is converted into the gravitational potential energy of the container through energy storage conversion device, traction machine and container lifting device. When the power demand of the ship's power grid is high, the energy is released to generate electricity, and the system automatically switches between gravity energy storage mode and gravity energy release mode according to real-time power comparison.
[0021] The shaft-driven generator is the energy input terminal of the system, located on the propeller shaft connected to the ship's main engine and operating in tandem with it. When the ship's main engine drives the propeller to propel the ship, it excites the rotor of the shaft-driven generator, which then generates three-phase alternating current, thus producing electricity synchronously. Under normal sea conditions, the shaft-driven generator typically has a power margin, and this surplus power is precisely what this system captures and stores.
[0022] The energy storage conversion device adopts an AC-DC-AC topology with SPWM modulation, and its electrical topology diagram is shown below. Figure 2As shown, the system includes a shaft-driven generator frequency converter module connected in parallel with the DC bus, an energy storage traction machine frequency converter module, and a shipboard power grid side frequency converter module. All three modules utilize active front-end converters with IGBTs as power devices, enabling both rectification and inversion. The shaft-driven generator frequency converter module is connected to the shaft-driven generator and converts the AC output from the generator into electrical energy that meets the requirements of the shipboard power grid. The energy storage traction machine frequency converter module is connected to the traction machine and drives and controls it. The shipboard power grid side frequency converter module is connected to the shipboard power grid and enables bidirectional energy flow between the DC bus and the shipboard power grid.
[0023] The traction machine uses a gearless permanent magnet synchronous motor. Its operating states include motoring and generating. When the available power of the shaft-driven generator exceeds the total load power of the ship's electrical grid, the traction machine is in motoring mode, rotating forward to lift the container. When the available power of the shaft-driven generator is less than the total load power of the ship's electrical grid, the traction machine is in generating mode. Under gravity, the container descends, dragging the traction machine in reverse to generate electricity. The generated electrical energy is fed back to the DC bus through the energy storage traction machine's frequency converter module, and then supplemented to the ship's electrical grid through the grid-side frequency converter module.
[0024] A container lifting device is used to move containers up and down under the drive of a traction machine. The device includes a container spreader, counterweight, lifting guide rails, and a brake. The spreader and counterweight are connected to the traction machine via cables. The brake locks the spreader and counterweight when the traction machine is not in operation. Lifting guide shoes are installed on both sides of the spreader and counterweight. The shoe linings inside the guide shoes are matched and connected to the lifting guide rails to secure the spreader and counterweight to them, providing rigid guidance for the vertical movement of the container and counterweight, preventing swaying, and ensuring smooth operation.
[0025] Example 2 This embodiment provides a control method for a gravity energy storage system of a container ship traction machine based on a shaft-driven generator, which switches the operating mode of the gravity energy storage system of the container ship traction machine based on a shaft-driven generator as proposed in Embodiment 1. Figure 3 As shown, it includes the following steps: S1. The system is powered on and performs initialization checks.
[0026] Initialization checks include hardware self-test, system status synchronization and verification, and safety condition review. The hardware self-test targets the status of the frequency converter module, actuators, and sensors. It checks the power supply, capacitor charging status, and fault registers of the shaft-driven generator frequency converter module, energy storage traction machine frequency converter module, and ship electrical grid-side frequency converter module, confirming no historical faults or current alarms. It also checks the brake status of the traction machine to ensure it is in a reliable closed position, checks the contact signals between the lifting guide shoes and lifting rails of the container lifting device to confirm no abnormal disengagement or jamming, and verifies that the weight sensors and height encoder readings of the container spreader and counterweight are within reasonable ranges, confirming normal communication with the main controller. System status synchronization is mainly used to obtain real-time data such as the total load power, frequency, and voltage of the ship's electrical grid. The safety condition review checks for any intrusion of personnel or obstacles within the operating range of the container lifting device.
[0027] S2. Start the ship's main engine, which drives the propeller shaft to rotate, thereby driving the shaft-driven generator to run.
[0028] After the ship's main engine starts operating, its output shaft drives the propeller shaft to rotate via a gearbox or direct coupling, and the propeller begins to work to provide thrust to the ship. As the propeller shaft rotates, the rotor of the generator, which is mechanically connected to it, rotates synchronously, generating three-phase alternating current.
[0029] S3. Calculate the available power of the shaft-driven generator in real time and compare it with the total load power of the ship's electrical grid.
[0030] The available power of the shaft-driven generator is not the generator's maximum rated power, but rather the real-time dispatchable surplus power under current operating conditions. The total load power of the ship's electrical grid is obtained in real time through the ship's energy management system.
[0031] S4. When the available power of the shaft generator is greater than the total load power of the ship's electrical grid, the auxiliary diesel generator stops working, the system enters the gravity energy storage mode, the traction machine is in electric state, and it checks whether the container meets the energy storage conditions. If the container meets the energy storage conditions, the excess electrical energy of the shaft generator is converted into gravitational potential energy through the traction machine. If the container does not meet the energy storage conditions, the energy storage process ends.
[0032] The energy storage condition is that there is room for improvement at the current height of the container, such as... Figure 4 As shown, the specific steps of the energy storage process include: Release the brakes on the container spreader and counterweight, and drive the traction machine to lift the container.
[0033] The traction machine is controlled to enter electric mode by the energy storage traction machine frequency converter module, and starts smoothly according to the preset acceleration curve to begin lifting the container. During the lifting process, the system continuously compares the available power of the shaft generator with the sum of the total load power of the ship's electrical grid and the drive power of the traction machine in real time.
[0034] When the available power of the shaft-driven generator is greater than the sum of the total load power of the ship's electrical grid and the drive power of the traction machine, the traction machine is controlled to lift the container at a constant speed until the container no longer meets the energy storage conditions. The traction machine then stops working, and at the same time, the brakes of the container spreader and the counterweight are closed. The output power of the shaft-driven generator is adjusted to be the same as the total load power of the ship's electrical grid, giving priority to ensuring the power supply of the ship's electrical grid.
[0035] When the available power of the shaft-driven generator is less than the sum of the total load power of the ship's electrical grid and the drive power of the traction machine, the traction machine stops working, the brakes of the container spreader and counterweight are closed, and the output power of the shaft-driven generator is adjusted to be the same as the total load power of the ship's electrical grid, giving priority to ensuring the power supply of the ship's electrical grid.
[0036] When the traction machine is in motor mode, the formula for calculating the conversion of excess electrical energy from the shaft-driven generator into gravitational potential energy is as follows: In the formula, It is gravitational potential energy. This represents the available power of the shaft-driven generator. This represents the total load power of the ship's electrical network. This refers to the time it takes for the container to be lifted at a constant speed.
[0037] S5. When the available power of the shaft-driven generator is less than the total load power of the ship's electrical grid, the system enters the gravity energy release mode, the traction machine is in the power generation state, and it checks whether the container meets the energy release conditions. If the container meets the energy release conditions, it performs a descent energy release operation to convert the stored gravitational potential energy back into electrical energy, which, together with the shaft-driven generator, supplies power to the ship's electrical grid. If the container does not meet the energy release conditions, the energy release process ends.
[0038] The energy release condition is that there is room for the container to descend from its current height, such as... Figure 4 As shown, the specific steps of the energy release process include: Release the braking devices of the container spreader and counterweight, control the traction machine to lower the container, and drive the rotor of the traction machine to rotate to generate electricity.
[0039] Under the influence of gravity, the container descends, dragging the rotor of the traction machine to rotate, thus putting it into a power generation state. Mechanical energy is converted into electrical energy, which is fed back to the system's DC bus through the energy storage traction machine's frequency converter module.
[0040] During the descent power generation process, the system continuously monitors and compares in real time the sum of the output power of the shaft generator and the power generation of the traction machine with the total load power of the ship's electrical grid.
[0041] When the sum of the output power of the shaft generator and the power generation of the traction machine is greater than the total load power of the ship's electrical network, the traction machine is controlled to lower the container at a constant speed until the container no longer meets the energy release condition. The traction machine then stops working, the brakes of the container spreader and the counterweight are closed, and the output power of the shaft generator is adjusted to be the same as the total load power of the ship's electrical network. If the sum of the output power of the shaft generator and the power generation of the traction machine is less than the total load power of the ship's electrical grid, the traction machine will stop working, the brakes of the container spreader and counterweight will be closed, and the output power of the shaft generator will be adjusted to be the same as the total load power of the ship's electrical grid. It may be necessary to start the auxiliary diesel generator to make up for the remaining power gap and prioritize the stability of the electrical grid.
[0042] When the ship's main engine power is insufficient, start the diesel auxiliary generator, shut down all non-essential electrical loads on the ship, release the brakes on the container spreader and counterweight, and control the traction machine to lower the container according to power requirements.
[0043] The rest is the same as in Example 1.
[0044] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.
Claims
1. A gravity energy storage system for container ship traction machines based on a shaft-driven generator, characterized in that, Includes shaft-driven generators, energy storage conversion devices, traction machines, and container lifting devices. The energy storage conversion device includes a shaft-driven generator frequency converter module, an energy storage traction machine frequency converter module, and a ship power grid side frequency converter module connected in parallel with the DC bus. The shaft-driven generator frequency converter module is connected to the shaft-driven generator and is used to convert the AC power output by the shaft-driven generator into electrical energy that meets the requirements of the ship power grid. The energy storage traction machine frequency converter module is connected to the traction machine and is used to drive and control the traction machine. The ship power grid side frequency converter module is connected to the ship power grid and is used to realize bidirectional energy flow between the DC bus and the ship power grid. The container lifting device is used to realize the lifting and lowering movement of containers under the drive of a traction machine; The excess electrical energy of the shaft-driven generator is converted into the gravitational potential energy of the container through the energy storage conversion device, traction machine and container lifting device. When the power demand of the ship's power grid is high, the energy is released to generate electricity, and the system automatically switches between gravity energy storage mode and gravity energy release mode according to real-time power comparison.
2. The gravity energy storage system for container ship traction machines based on shaft-driven generators according to claim 1, characterized in that, The shaft-driven generator is mounted on the propeller shaft that is connected to the ship's main engine.
3. The gravity energy storage system for container ship traction machines based on a shaft-driven generator according to claim 1, characterized in that, The traction machine adopts a gearless permanent magnet synchronous motor, and its working state includes motoring state and generator state. When the available power of the shaft-driven generator is greater than the total load power of the ship's electrical grid, the traction machine is in motoring state; when the available power of the shaft-driven generator is less than the total load power of the ship's electrical grid, the traction machine is in generator state.
4. The gravity energy storage system for container ship traction machines based on shaft-driven generators according to claim 1, characterized in that, The container lifting device includes a container spreader, a counterweight, a lifting guide rail, and a brake. The container spreader and the counterweight are connected to the traction machine via cables. The brake is used to lock the container spreader and the counterweight when the traction machine is not in operation.
5. The gravity energy storage system for container ship traction machines based on a shaft-driven generator according to claim 4, characterized in that, The container spreader and counterweight are equipped with lifting guide shoes on both sides, and the shoe lining inside is matched and connected with the lifting guide rail to fix the container spreader and counterweight on the lifting guide rail.
6. A control method for a gravity energy storage system of a container ship traction machine based on a shaft-driven generator, characterized in that, Switching the operating mode of the container ship traction machine gravity energy storage system based on a shaft-driven generator as described in any one of claims 1-5 includes the following steps: The system powers on and performs initialization checks. Start the ship's main engine, which drives the propeller shaft to rotate, thereby driving the shaft-driven generator to run; The available power of the shaft-driven generator is calculated in real time and compared with the total load power of the ship's electrical grid: When the available power of the shaft-driven generator is greater than the total load power of the ship's electrical grid, the auxiliary diesel generator stops working, the system enters the gravity energy storage mode, the traction machine is in electric state, and it detects whether the container meets the energy storage conditions. If the container meets the energy storage conditions, the excess electrical energy of the shaft-driven generator is converted into gravitational potential energy by the traction machine. If the container does not meet the energy storage conditions, the energy storage process ends. When the available power of the shaft-driven generator is less than the total load power of the ship's electrical grid, the system enters the gravity energy release mode, the traction machine is in the power generation state, and it detects whether the container meets the energy release conditions. If the container meets the energy release conditions, it performs a descent energy release operation to convert the stored gravitational potential energy back into electrical energy, which, together with the shaft-driven generator, supplies power to the ship's electrical grid. If the container does not meet the energy release conditions, the energy release process ends.
7. The control method for the gravity energy storage system of a container ship traction machine based on a shaft-driven generator according to claim 6, characterized in that, The energy storage condition is that there is room for the container to be lifted at its current height. The specific steps of the energy storage process include: Release the brakes on the container spreader and counterweight, and drive the traction machine to lift the container; When the available power of the shaft-driven generator is greater than the sum of the total load power of the ship's electrical grid and the driving power of the traction machine, the traction machine is controlled to lift the container at a constant speed until the container no longer meets the energy storage conditions. The traction machine then stops working, and at the same time, the brakes of the container spreader and the counterweight are closed. The output power of the shaft-driven generator is adjusted to be the same as the total load power of the ship's electrical grid. When the available power of the shaft-driven generator is less than the sum of the total load power of the ship's electrical grid and the driving power of the traction machine, the traction machine stops working, the brakes of the container spreader and the counterweight are closed, and the output power of the shaft-driven generator is adjusted to be the same as the total load power of the ship's electrical grid.
8. The control method for the gravity energy storage system of a container ship traction machine based on a shaft-driven generator according to claim 6, characterized in that, The energy release condition is that there is room for the container to descend from its current height. The specific steps of the energy release process include: Release the braking devices of the container spreader and counterweight, control the traction machine to lower the container, so as to drive the rotor of the traction machine to rotate and generate electricity; When the sum of the output power of the shaft-driven generator and the power generation of the traction machine is greater than the total load power of the ship's electrical network, the traction machine is controlled to lower the container at a constant speed until the container no longer meets the energy release condition. The traction machine then stops working, the brakes of the container spreader and the counterweight are closed, and the output power of the shaft-driven generator is adjusted to be the same as the total load power of the ship's electrical network. If the sum of the output power of the shaft-driven generator and the power generation of the traction machine is less than the total load power of the ship's electrical network, the traction machine stops working, the brakes of the container spreader and the counterweight are closed, and the output power of the shaft-driven generator is adjusted to be the same as the total load power of the ship's electrical network.
9. The control method for the gravity energy storage system of a container ship traction machine based on a shaft-driven generator according to claim 6, characterized in that, When the traction machine is in motored mode, the formula for calculating the conversion of excess electrical energy from the shaft-driven generator into gravitational potential energy by the traction machine is as follows: In the formula, It is gravitational potential energy. This represents the available power of the shaft-driven generator. This represents the total load power of the ship's electrical network. This refers to the time it takes for the container to be lifted at a constant speed.
10. The control method for the gravity energy storage system of a container ship traction machine based on a shaft-driven generator according to claim 6, characterized in that, When the power of the ship's main engine is insufficient, start the diesel auxiliary generator, shut down all non-essential electrical loads on the ship, release the brakes on the container spreader and counterweight, and control the traction machine to lower the container according to power requirements.