WIND TURBINE CONTROL DESIGN TO REDUCE CAPITAL COSTS P. Jeff Darrow(Colorado School of Mines) Alan Wright(National Renewable Energy Laboratory) Kathryn E. Johnson(Colorado School of Mines)

Overview  Introduction  Wind Turbine Description  Baseline Controller Description  Design Load Cases (DLCs)  Preliminary Results  Conclusions  Future Work

Introduction - Work Site(s)  This research in this project is being performed at two sites  The National Wind Technology Center (NREL)  Colorado School of Mines

Introduction - Motivation  Increasing demand for wind energy  Wind turbines operate in extreme conditions  Experiencing both fatigue and extreme loads  IEC dictates a minimum design life of 20 years  The current design approach is to use robust components  This causes a high capital cost of each wind turbine

Introduction – Goals  Perform a full loads case analysis  Help guide wind turbine control research  Identify design driving events and the responsible factors  Develop advanced control techniques to mitigate prominent loads  Show a potential to reduce capital costs with controller design

Introduction - General  This research is still in progress  Results are specific to the CART3

Controls Advanced Research Turbine Wind Turbine Description

Regions of Operation

Controls Advanced Research Turbines  The NWTC has two primary research turbines  Model: Westinghouse WTG-600  Originally from a wind farm in Oahu, Hawaii  However, they are not ordinary (industry) turbines  Specially outfitted with extra sensors and actuators for research purposes  Original pitch system replaced  New generator system added  New control system added

Control Actuators  Blade pitch  Limit of 18˚/second  Generator torque  Limit of 3581 N*m  Yaw  Limit of 0.5 ˚/second

CART3 Characteristics  3 bladed, upwind  Active yaw  Rated power: ~600 kW  Rated torque: 3581 N*m  Class IIB rating by IEC  Rated wind speed: 13.5 m/s  Rated rotor speed: 41.7 rpm  C p,max :

CART3 Model for Simulations  Three main components  Rotor  Tower  Nacelle  Modeled with the NREL design- code FAST  Uses many DOF’s to model turbine dynamics

CART Model - DOFs 1 st Tower Side-to-Side Mode Shaft Torsion 1 st Tower Fore-Aft Mode

Design Implementation Verification Baseline Controller Description

Baseline Controller Design  Baseline controller works in regions 2, 2.5, and 3  Region 2 uses torque control:  Regions 2.5 provides a linear torque curve  Region 3 uses a PID type collective pitch controller

Baseline Controller Implementation  The fore mentioned control scheme is implemented using a DLL linked to the FAST model  Region 2 control is built into the FAST simulator  Region 3 control is defined in the linked DLL  Operation of overall controller was verified for proper operation

Baseline Controller Verification

Design Load Cases

Design Load Cases (DLC’s)  Defined by IEC Document  Provides load cases to predict turbine loading  Focus on cases that do not require controller logic for start-up/shutdown  Each applicable case applied to the CART3 model  Resulting loads observed

DLCs of Interest DLC Winds Controls/Events ModelSpeed 1) Power Production 1.1NTMV in < V hub < V out Normal Operation 1.3ETMV in < V hub < V out Normal Operation 1.4ECDV hub = V r, V r ±2m/sNormal Operation: ±Δ Wind Direction 1.5EWSV in < V hub < V out Normal Operation: ±Δ Vert & Horz Shear 1.6NTMV in < V hub < V out Normal Operation 2) Power Production w/ Occurance of Fault 2.1NTMV hub = V r, V out Pitch Runaway  Shutdown 2.3EOGV hub = V r, V r ±2m/s, V out Loss of Load  Shutdown 6) Parked 6.1aEWMV hub = 0.95*V 50 Yaw = 0°, ±8° 6.2aEWMV hub = 0.95*V 50 Loss of Grid ; -180° < Yaw <180° 6.3aEWMV hub = 0.95*V 1 Yaw misalignment of +30° 7) Parked w/ Occurance of Fault 7.1aEWMV hub = 0.95*V 1 Seized Blade; Yaw = 0°, 8°

Only a representative subset of the total available results is presented here Preliminary Results

DLC Power Production -- Extreme Turbulence Model -- No faults

DLC Power Production -- Extreme Turbulence Model -- No faults

DLC Power Production -- Extreme Turbulence Model -- No faults

DLC Power Production -- Extreme Turbulence Model -- No faults

DLC Power Production -- Extreme Operating Gust -- Internal Electrical System Fault

DLC Power Production -- Extreme Operating Gust -- Internal Electrical System Fault

DLC Power Production -- Extreme Operating Gust -- Internal Electrical System Fault

DLC Power Production -- Extreme Operating Gust -- Internal Electrical System Fault

DLC Parked -- Extreme Wind Model ° Yaw misalignment

DLC Parked -- Extreme Wind Model ° Yaw misalignment

DLC Parked -- Extreme Wind Model ° Yaw misalignment

DLC Parked -- Extreme Wind Model ° Yaw misalignment

Conclusions & Future Work

Conclusions  The CART3 had been successfully modeled in FAST  The baseline controller has been developed and implemented in simulation  All DLCs of interest have been simulated  We currently have all of the data needed to conduct an in depth analysis

Future Work  Continue work to quantify design driving events  Design and simulate controllers to handle prominent cases  Re-run the suite of DLCs to show new results  We hope to show a potential to reduce the capital costs of a wind turbine by controller design

Acknowledgements  Marshall Buhl  NREL  Jason Jonkman  NREL

Have a wonderful day Thank You