Nowadays, the rapid development of global logistics has accelerated the circulation of goods in ports. The large-scale equipment in ports needs to complete the corresponding vertical movement during operation. This mode of mobile operation consumes a lot of energy and also results in a large amount of regenerative energy generated by large-scale lifting equipment. Only by deeply exploring the energy saving technology of large lifting equipment can we meet the requirements of energy saving and emission reduction in our country.

  Adopt energy-saving and consumption-reducing technologies in the main circuit and circuit control mode [Port energy-saving equipment]

  The internal main circuit voltage structure of large port lifting machinery usually adopts a three-phase half-bridge voltage transformer. The rectifier of the three-phase half-bridge voltage transformer is composed of a topological structure. The voltage structure on the AC side has extremely high stability. Its internal structure has no neutral line connection and operates with a three-phase symmetrical internal structure. The three-phase half-bridge voltage transformer can be simultaneously controlled by six IGBT power switches during operation, with relatively strong operability. Installing a mesh filter inside the rectifier topology allows the internal higher-order harmonics to be observed through the external equipment of the rectifier. The unit power of the main circuit is affected by factor rectification. Adopting a power grid with the same voltage as the main circuit on the communication side. When the unit power factor changes to the inverter state, the current of the main circuit on the AC side differs from the unit power voltage by about 180°.

  In order to enable large-scale lifting machinery and equipment to achieve the goal of energy saving and consumption reduction during construction operations, relevant technologies can first be adopted to control the current and voltage of the main circuit. During the operation of the equipment, the originally adopted three-phase half-bridge voltage-type controller can be changed, that is, the original PWM rectifier can be replaced by a PI controller. The parameters of the current can be changed at the rotating coordinate of the rectifier to convert the original AC current to a constant DC current, and error-free regulation can be carried out on the entire circuit system. The purpose of energy saving and consumption reduction can be achieved by changing the current of the main circuit. Moreover, the control mode of the circuit can be changed by controlling the magnitude of the current. The control mode of the circuit can be adjusted through the constant direct current technology. In the actual operation and running of large-scale lifting machinery and equipment, the filtering capacitance inside the circuit will detect the voltage in volts inside the circuit according to the power magnitude of the reactive current component.

  It can also accurately measure and detect the voltage amplitude. By changing the energy value of the original circuit through the current frequency of the internal circuit, the energy value controlled by the circuit can be kept in a constant state, ensuring that the current on the AC (alternating current ) side is active current, improving the stability of the circuit system and ensuring the operating state of the system power factor. Through the setting of communication technology, the goal of energy saving and consumption reduction can also be achieved. The communication mode and the electric current of communication equipment in circuit control are mainly controlled by the main control system. During the communication control process, the main circuit can complete the connection and application of reactive power compensation in the form of sending reactive power instructions. This can not only enable large lifting equipment to achieve energy saving and consumption reduction during operations, but also have a certain impact on the stability of the internal circuit system of large lifting equipment.

  Adopt energy-saving and consumption-reducing technologies by using energy feedback devices.

  Large-scale lifting machinery and equipment will carry containers to load goods during operations. The fixed storage sites of containers usually use large-scale lifting machinery such as rubber-tyred gantry cranes for operations. Its internal devices are mainly composed of large vehicles, small vehicles and lifting devices. Install frequency conversion devices on the internal system of the container, control the current through frequency conversion inside the container. When adjusting the speed of the equipment, install and place them in the form of an inverted installation of the frequency converter, with the DC bus inside the container as the installation and inversion control point. In terms of the braking method, change the original basic braking method and adopt the form of braking resistors for braking. The above is the principle of the energy feedback device when large-scale lifting machinery and equipment are in construction operations.

  Adopt energy-saving and consumption-reducing technologies in the energy feedback device. Through reform the original energy feedback device and controlling the contactor, the uncontrolled rectification system and the energy feedback device can be freely adjusted. When the mechanical equipment is in operation, the energy feedback device and the uncontrolled rectification system are adjusted. Once an accident or failure occurs in the large lifting equipment, the switch controller of the uncontrolled rectification system can be immediately cut off, and the energy feedback system can also be used for inspection to avoid damage to large lifting machinery caused by equipment failure, and also ensure the personal safety of the construction workers, improving the safety and reliability of port operations. In the investigation of large port lifting equipment, it was found that the energy feedback device was installed in a 75t ship loader, and an uncontrolled rectified current system was adopted in the steel plate ship loader. Through comparison, it was found that the ship loader equipped with the uncontrolled rectified current system and the energy feedback device significantly saved more electricity than the ship loader without the device, and more than 35% of electricity could be saved during short-term construction operations.

  Through the above comparative research, it is found that by installing an energy feedback device inside large lifting equipment, the operating conditions of the large machinery can be known through the energy feedback of the mechanical equipment, and the power consumption can also be saved, achieving the purpose of energy conservation and consumption reduction. By installing an energy feedback device on the container, the operator can grasp the status of the internal parts of the mechanical equipment at any time. Once the internal device is found abnormal, you can immediately ask the relevant technical personnel to detect and repair, avoiding operation errors caused by the instability of the internal system of the container ,reducing the frequency of rework, and to a certain extent, it has achieved the effect of energy conservation and consumption reduction.

  Through the research on the energy feedback device, the internal structure of the traditional large lifting equipment has been improved, reducing errors during the operation of the large lifting equipment and significantly enhancing its working efficiency. Experiments show that whether the energy feedback device is installed on large ships for loading and unloading, large loaders, or large port rubber-tyred cranes, through the setting of the technical system, operators can grasp the internal conditions of the mechanical equipment at any time, which significantly improves the working efficiency of the large lifting equipment and also has a certain impact on the economic benefits of the port, and to a certain extent, it has achieved the effect of energy conservation and consumption reduction.

  With the continuous development of China's foreign trade economy, the demand for energy and materials in port trade is increasing. Applying energy conservation and consumption reduction technologies to large port hoisting equipment conforms to the basic awareness of energy conservation in modern society and the strategy of sustainable development. Energy conservation and consumption reduction technologies can be adopted in the main circuit and circuit control. The external equipment technology of the circuit rectifier can be used to change the electric current of mechanical equipment. Moreover, by installing energy feedback devices, the internal conditions of mechanical equipment can be grasped at any time, reducing the malfunctions during the operation of the equipment and improving the construction accuracy of large hoisting equipment, so as to achieve the purpose of energy conservation and consumption reduction.