Siemens ECO RTG optimised control for gantry cranes

ECO RTG from Siemens is designed to provide improved control functions for the operation of rubber-tyred gantry cranes, based on the simulation of the load curve and the optimisation of the control of the diesel-electric hybrid drive. By storing braking energy in ultracapacitors when containers are lowered and by optimising the utilisation of energy, fuel consumption can be reduced by approximately 70%.

The energy demand of a gantry crane is determined by means of simulation tools and optimised with the help of special drive algorithms. In order to optimise the drive system, the ECO-RTG applies an equivalent consumption minimisation strategy (ECMS). Based on a mathematical model of the motor and the ultracapacitors, the exact performance setpoint value is determined in real time for the motor and the ultracapacitors to ensure minimum fuel consumption. This means that when required the control algorithm receives as much energy as possible from the ultracapacitors, but at the same time it also ensures that the stored energy is never completely used up. During the entire operating cycle of the crane, there is a balance between the amount of energy supplied from the ultracapacitors and the amount of energy that is stored in them when braking and lowering.

The control function continuously adjusts the energy consumption by means of approximations and permanent adaptations. If, for example, more containers than usual must be loaded, the system adapts itself to the new situation. Alternatively, if the crane is in no-load mode and only auxiliary systems are consuming energy, this energy is only supplied by the ultracapacitors and the motor is switched off.