Performance Improvement of a Hydraulic Active/Passive Heave Compensation Winch Using Semi Secondary Motor Control: Experimental and Numerical Verification

Geir-Arne Moslått,Michael Rygaard Hansen,Damiano Padovani

doi:10.3390/en13102671

Geir-Arne Moslått, Michael Rygaard Hansen + Show 1 more

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https://doi.org/10.3390/en13102671

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Journal: Energies	Publication Date: May 25, 2020
Citations: 6	License type: CC BY 4.0

Affiliation: National Oilwell Varco (Norway), University of Agder

Abstract

In this paper, a newly developed controller for active heave compensated offshore cranes is compared with state-of-the-art control methods. The comparison is divided into a numerical part on stability margins as well as operational windows and an experimental validation of the expected performance improvement based on a full-scale testing on site with a crane rated to 250 metric tons. Such a crane represents the typical target for the new control method using a combination of active and passive hydraulic actuation on the main winch. The active hydraulic actuation is a hydrostatic transmission with variable-displacement pumps and variable-displacement motors. The new controller employs feedforward control of the motors’ displacement so that the window of operation is increased and, simultaneously, oscillations in the system are markedly reduced.

Highlights

There are high demands for motion compensated offshore cranes today, mostly related to oil and gas, and the offshore wind industry
The quayside test was conducted with low winch load and simulated crane’s tip motions
The positive effects of keeping a high displacement setting at low speed were confirmed since the classic controller lead to higher and more oscillatory pressures and winch motion, especially at low speeds shown in Figures 16 and 17

Summary

Introduction

There are high demands for motion compensated offshore cranes today, mostly related to oil and gas, and the offshore wind industry. The most common solution is equipping the crane with a 1D compensation system, and the vessel with a dynamic positioning system keeps the position in the horizontal plane. This approach works very well for most subsea operations since the payload motion in the horizontal plane due to the vessel’s roll, pitch, and yaw becomes insignificant by the dampening effect when the payload is below the sea surface. If 1D or 3D compensation is used, the most common methods for the vertical compensation of the motion are controlling the wire speed in the winch or using a passive motion compensator mounted directly on the crane’s hook. When the system is drum controlled, it is usually done with a hydraulic transmission that can be categorized into five types [1,2,3,4]: Primary controlled systems with variable-displacement pumps and fixed-displacement motors (VPFM) operated in the closed-circuit configuration

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Discussion

Conclusion