Research And Application Of Potential Energy Feedback Analysis For Port Gantry Crane

In the era of rapid technological development,energy and environmental issues have become increasingly prominent,and have attracted the attention of countries around the world.Energy conservation and environmental protection have become the theme of the times.Port crane is becoming one of the important researching objects in the energy-saving and environmental-protection field because of its high petrol consumption,low efficiency,severe pollution and wasting of gravitational potential energy.Therefore,it is of great significance to study the problem of energy saving and emission reduction of cranes.Currently energy saving solutions of crane is mainly focused on the energy storage and reuse of the renewable energy from the driving motor which is dragged by potential load.As an auxiliary power source,supercapacitor does not participate in the work during light loads,and provide partial energy to maintain normal operation of the system during heavy loads.Practice shows that under this strategy,the supercapacitor energy utilization rate and the potential energy recovery rate are low,and the maximum effect of energy saving is not achieved.In view of the current shortage of supercapacitor energy utilization and low energy recovery efficiency,this thesis takes the 40.5T gantry crane as the object,and conducts in-depth theoretical analysis on the hybrid power system.It proposes to adjust the load power allocation strategy in time according to the supercapacitor voltage change,so that the super capacitor energy can be utilized preferentially and fully.The thesis also establish a mathematical model,and applicate software to simulate and platform experiments.Ultimately,the supercapacitor energy supply ratio exceeds 75%,the energy recovery efficiency reaches 85%,and the energy recovery-consumption ratio reached 62%.The main contents of this paper are as follows:(1)By comparing the traditional crane with the hybrid crane,this paper find the necessity of adopting the hybrid crane.The detailed study of the characteristics of the important parts in the system can provides a basis for the formulation of the energy control strategy.(2)This paper established the dynamic model of the hoisting mechanism of the gantry crane,and made detailed analysis with the load lifting and lowering,the energy transmission direction when lowering,energy consumption and conversion characteristics of operations.It is concluded that the system has a large amount of energy which is recoverable and of high conversion efficiency.The energy is mainly come from the potential energy of the hoisting mechanism,and the super capacitor can recover the energy.(3)This paper studied the energy control strategy of hybrid power system based on supercapacitor,and make out the strategy of adjusting load power distribution following supercapacitor voltage change.The power supply ratio of super capacitor can be guaranteed to be more than 50% regardless of the load size,which increased utilization of Super capacitor energy.The paper also studied the supercapacitor charge and discharge and voltage equalization control strategies,which adopted the method of flying capacitors adjusting the voltage balance between the supercapacitors,and a fast and safe charging strategy of constant current and constant power.Through calculating the relationship between the load power and the optimal engine speed,the paper improved the overall energy saving effect of the system.(4)The paper established the mathematical model of important parts of the system,and built the simulation model of the system control strategy in Matlab/simulink to verify the reliability of the supercapacitor+diesel hybrid system and the feasibility of the energy control strategy.(5)The paper applied the system energy control strategy to the comprehensive experimental platform of port equipment energy-saving technology,which simulates the actual situation,setting the medium and small power load and high-power load working conditions,conducting the platform energy conversion efficiency to verify experiment and the load potential energy feedback.Furthermore,conducting the experiment,it verifies platform operation reliability and the recovery efficiency of potential energy in the system.