A numerical DP module For design and operations

Transcription

1 A numerical DP module For design and operations A. Ledoux, B Lecuyer, C. Le Cunff Principia R.D. PRINCIPIA

2 Summary Numerical Tool: Diodore Modeling of floating structure Modeling of environment Ship simulator DP module DP control system Allocation/compensation Type of analyses Application: offloading PRINCIPIA

3 DIODORE Applications Strength, loads & FEM coupling Sea-keeping Stability DP module Mooring & UFL design Marine operations PRINCIPIA

4 Software Architecture PRE Hydrostatics & mass breakdown HYDRO Hydrodynamics loads & pressures MECA Frequency/Time domain motion simulation POST Post-processing, animations, statistics,plots PRINCIPIA

5 Hydrodynamics Diffraction-Radiation Source model Infinite or finite depth Without or with forward speed Drift forces Control point in the fluid (pressure & velocities) Moonpool & side by side methodologies PRINCIPIA

6 Hydrodynamic model Hydrodynamic loads based on diffraction-radiation sink source method PRINCIPIA

7 Sea keeping Motions, accelerations at any points Splash zone, green water, slamming occurrence Damping formulations Multi-structures Long crested & short crested sea states Advanced features: Sloshing/sea-keeping coupling Stabilization devices (anti-roll tanks, foils ) Multi-peaks multi-directional sea states Automatic pilots PRINCIPIA

8 Mooring design Mooring design (extreme & fatigue) Static, quasi-static simulations Squall winds API 2SK rules applications Compliant to BV rule PRINCIPIA

9 Ship motion 6-dof response assessed from the efforts on the ship, including : environmental loads mooring control units maneuverability (Speed not at scale) PRINCIPIA

10 The DP Module DP CONTROL SYSTEM Wind FFWD F wind + + F DP DP Ship External loads F reg PID Feedback loop x,y,ψ Computed position (LF) + Set point Ideal wind feed forward PID corrector Anti-reset windup to prevent saturation PRINCIPIA

11 PID regulator DP PILOT : PID REGULATOR Proportional = Stiffness Integral = Mean offset correction Derivative = Damping Ship response PID time PRINCIPIA

12 The DP Module THRUSTER ALLOCATION DP Pilot ALLOCATION F DP = Freg dynamic F DP static F DP = Fext PRINCIPIA

13 Linking Thrusters Should be of the same type Will be commanded the same thrust and azimuth PRINCIPIA

14 Linking Thrusters ALLOCATION Will be commanded the same thrust and azimuth Allocated as single equivalent thrusters PRINCIPIA

15 The DP Module FIRST STEP : LINEAR ALLOCATION B : Allocation matrix based on DP system geometry Corrective effort Thruster commands F = B U Solved with energy cost-function optimization : U = B F with B = B T.(B.B T ) 1 PRINCIPIA

16 The DP Module THRUSTER ALLOCATION PRINCIPIA

17 The DP Module SECOND STEP : COMPENSATION Azimuth compensation Device fixed to maximum azimuth Re-allocation PRINCIPIA

18 The DP Module SECOND STEP : COMPENSATION Thrust compensation Device fixed to maximum thrust Re-allocation PRINCIPIA

19 The DP Module STATION KEEPING CAPABILITY ANALYSIS Mechanical processor in frequency domain Define thrusters + DP system (only static parameters) Define environment (API) Draw capability plots TIME SIMULATION Mechanical processor in time domain Define thrusters + DP system & pilot Run LF simulation together with any other mechanical model (mooring, etc) PRINCIPIA

20 The DP Module CONTROL UNITS Tunnel thruster Directional thruster (reversible or not) Screw propeller & rudder Azimuth thruster PRINCIPIA

21 The DP Module CAPABILITY PLOT : IMCA-STANDARD Overall DP system performance : Maximum wind speed before system saturation 330 Max wind speed (knots) 0 30 vs Incidence of mean environmental forces Same direction for wind, wave and current Wave and current related to wind speed 180 PRINCIPIA

22 The DP Module CAPABILITY PLOT : API-STANDARD DP system solicitation in given environment : Thruster solicitation vs Ship heading Thrust (kn) Optimize ship availability for operations Bow truster Port Azimuthal Stbd Azimuthal Aft Azimuthal PRINCIPIA

23 The DP Module TIME DOMAIN SIMULATIONS Simulate ship response to environment including special events (scenario) or environmental changes (squall winds) PRINCIPIA

24 The DP Module TIME DOMAIN SIMULATIONS DP pilot parameters : - Gains, thrust saturation, azimuth saturation - Set point, actualization time lap PRINCIPIA

25 Applications TANDEM OFF-LOADING DWT DP-tanker L320m x B55m x T8.2m 2 x 75kN tunnel thrusters + 2 x 100kN azimuth thrusters OCIMF coefficients for wind & current polars Environment : wind : 9.6knots from 75 N wave : Hs=2.3m, Tp=12s from 300 N current : 0.65m/s to 330. PRINCIPIA

26 Applications TANDEM OFF-LOADING Capability analysis : normal / failure mode Full Safe operating range 300 Normal Thrust Allocation (kn) 60 Bow tunnel Stern tunnel Port azimuthing Stbd azimuthing Reduced Safe operating range Bow thruster failure Thrust Allocation (kn) 60 Bow tunnel Stern tunnel Port azimuthing Stbd azimuthing DP unable to maintain ship position PRINCIPIA

27 Applications TANKER RESPONSE TO SQUALL WIND Surge and Sw ay motions (m) Wind speed (m/s) 7.5 Wind speed Wind direction Wind direction (CWN) Surge Sway -60 Thrust Allocation (kn) Tanker Trajectory Bow tunnel Stern tunnel Port azimuthing Stbd azimuthing PRINCIPIA

28 Concluding remarks DP Module Validation : Field Development Ship (SAIBOS) Development : frequency domain PRINCIPIA