Enabling Energy Savings in Offshore Mechatronic Systems by using Self-Contained Cylinders

Abstract

This paper proposes a novel actuation system for an offshore drilling application. It consists of three self-contained electro-hydraulic cylinders that can share and store regenerated energy. The energy saving potential of the proposed solution is analyzed through a multibody system simulation. The self-contained system demonstrates superior energy efficiency compared to the benchmark system representing the stateof-the-art approach used today (i.e., valve-controlled cylinders by means of pressure-compensated directional control valves and counterbalance valves, supplied by a centralized hydraulic power unit). Due to the "power on demand" capability, the cancellation of the throttling losses, and the opportunity to recover energy in motoring quadrants, the self-contained system consumes 83.44% less energy without affecting the system's performance.

A Comparison Study of a Novel Self-Contained Electro-Hydraulic Cylinder versus a Conventional Valve-Controlled Actuator—Part 2: Energy Efficiency

“…All tests were carried out for a working cycle with maximum payload (i.e., with a load mass equal to 304 kg). The motion profile generator, presented in [27], provides reference signals for the desired piston position and velocity, as illustrated in Figure 6. The cylinder's piston extends and retracts between the start position x C,0 = 50 mm and the desired position x C,re f = 450 mm, at a desired maximum velocity v C,max = 120 mm/s.…”

“…Two scenarios are therefore addressed; the first one ( Figure 10a) focuses on measurements from the test setup. The scenario #2 (Figure 10b) considers an HPU equipped with a load-sensing pump and driven by an induction motor running at 1500 rpm (the losses of the HPU are simulated based on the model presented in [27]). Full energy recovery is then assumed for the SCC in this second situation (i.e., the energy dissipated in the brake resistor when the SCC is lowering the crane boom is now reused).…”

“…Moreover, the lack of experimental comparisons in terms of energy consumption and efficiency between SCCs and conventional solutions for load-carrying applications is evident. Only a limited number of simulation studies applying the SCC technology to load-carrying applications and investigating the energy-saving potentials compared to existing hydraulic systems were identified [26,27].…”

A Comparison Study of a Novel Self-Contained Electro-Hydraulic Cylinder versus a Conventional Valve-Controlled Actuator—Part 1: Motion Control

“…The hydraulic, valve-controlled drive taken into account as the benchmark is used in several industrial applications, such as offshore cranes and oil drilling equipment, and represents the state of the art (e.g., [19][20][21][22]). The system consists of a centralized hydraulic power unit (HPU) providing a constant supply pressure (p S ) and a fixed return pressure (p R ) to the valve-controlled cylinder, as illustrated in Figure 4.…”

“…Hence, the pressure feedback's parameters are first chosen so that the desired damping ratio of the system is obtained before designing the motion controller for the damped system; a complete explanation of the process used to derive these parameters is included in Appendix B. Further on, the motion profile generator presented in [19] provides reference signals for the desired piston velocity (v C,re f ) and piston position (x C,re f ) to the motion controller. The motion controller consists of the combination of two blocks, namely the velocity feedforward and the position feedback.…”