Balanced heave compensation
Balanced heave compensation is a technology engaging the principle of a balanced-arm lamp for offshore motion compensation.
Working principle
The technical working principle can be summarized as converting the non-linear force of a gas,- or hydro-pneumatic spring into an adjustable lineair force, by several mechanical measures. The technology comprises a series of patented inventions by NHLO licensed to and marketed by Seaqualize.[1]
Research project
In cooperation with IHC and research partners MARIN and ECN a scale model of a first device comprising the technology, an offshore access bridge has been tested. Seaqualize is currently working on a full scale prototype of the access bridge. The project has been subsidized by the Dutch Ministry of Economical affairs as a Renewable Energy project.
The research project indicates balanced heave compensation enables a range of potential benefits compared to currently available solutions. This may lead to improvements and cost savings in (engaging) heave compensation systems.
Comparison to traditional heave compensation systems
Balanced heave compensation (BHC) differs from traditional (spring based) Passive Heave Compensation (PHC) and Active Heave Compensation(AHC) in several ways.
In traditional spring based heave compensation systems the movement of the mass is parallel to the movement of the spring cylinder. A passive heave compensation system is in effect a mass spring system, it stabilizes a certain mass in a single position of the spring, in that position the spring and the mass are balanced. In other positions of the spring the mass and the spring are not balanced and the mass will tend to start moving towards the stabilized position due to residual forces in the spring. Only in certain (preset) conditions a mass spring system can be beneficial for heave compensation, in other conditions it has unwanted effects known as load amplification. An active heave compensation system adds an active component to a passive heave compensation system in order to counteract these residual forces.
In BHC systems the movement of the mass is not parallel to the movement of the spring cylinder, leading to much lower residual forces, and therefore lower requirements on the active components. In BHC systems load amplification is unlikely to occur since variations in the wave pattern have a negligible effect on the working principle. BHC is therefore best characterized as a AHC with a lower power requirement.