Optimal Energy Control of a Rubber Tyre Gantry with Potential Energy Recovery

The Rubber Tyre Gantry (RTG) cranes is a hoisting equipment usually used in port terminals to move shipping containers from one location to another. However, most of RTGs are operated inefficiently, hence a high energy cost is incurred. The reason of poor operation efficiency of RTG crane is that the equipment is operated at a constant speed during true vertical lift, no matter how the load and/or true vertical lift change, also during the lowering of a container, the regenerative breaking energy is usually dissipated through a resistor bank. This work therefore proposes an energy management model that would improve the energy efficiency of the RTG crane. First, we propose to optimally control the regenerative breaking energy to and from the battery bank taking into account the time-of-use tariff and maximum demand. Secondly, we propose to optimally control the hosting speed according to the variability of container weight and true vertical lift.