Power Conversion Group School of Electrical and Electronic Engineering The University of Manchester, UK DFIG Wind Turbine Control System Co-ordination to improve Drive- Train Reliability Ting Lei 1, M Barnes 1, Sandy Smith 1 1 University of Manchester

Power Conversion Group School of Electrical and Electronic Engineering The University of Manchester, UK Overview  Reliability of wind turbine subassemblies  DFIG wind turbine model  Basic control system  Mechanical & electric torque oscillations  Modified control schemes & protection circuit  Improvement through control coordination

Power Conversion Group School of Electrical and Electronic Engineering The University of Manchester, UK WT Subasembly Reliability

Power Conversion Group School of Electrical and Electronic Engineering The University of Manchester, UK DFIG Wind Turbine – overall control system

Power Conversion Group School of Electrical and Electronic Engineering The University of Manchester, UK PSCAD Set up –2-mass shaft model

Power Conversion Group School of Electrical and Electronic Engineering The University of Manchester, UK Converter Control System – RSC d – loop q – loop

Power Conversion Group School of Electrical and Electronic Engineering The University of Manchester, UK Converter Control System – GSC inner loop d – loop q – loop

Power Conversion Group School of Electrical and Electronic Engineering The University of Manchester, UK Mechanical Control System WT Controller

Power Conversion Group School of Electrical and Electronic Engineering The University of Manchester, UK Simulations with original controller 40% grid voltage drop for 0.5s Wind step from 12m/s – 13m/s ω r (pu) Pitch angle (degrees) Torque (pu ) Vdc (kV) ω r (pu) Torque (pu ) Vdc (kV)ir_abc (kA)

Power Conversion Group School of Electrical and Electronic Engineering The University of Manchester, UK Basic controller bandwidths coordination PWM: 4500Hz Grid f: 50Hz Shaft natural f: 2.55Hz GSC inner: 450Hz RSC current :10Hz DC-link: 10Hz Pitch controller: Bandwidths (Hz) ?

Power Conversion Group School of Electrical and Electronic Engineering The University of Manchester, UK Controller bandwidths – pitch controller

Power Conversion Group School of Electrical and Electronic Engineering The University of Manchester, UK Basic controller bandwidths coordination PWM: 4500Hz Grid f: 50Hz Shaft natural f: 2.55Hz GSC inner: 450Hz RSC current: 10Hz Pitch controller: 0.1 Hz Bandwidths (Hz) DC-link: 10Hz d-current:10Hz q-current:120Hz

Power Conversion Group School of Electrical and Electronic Engineering The University of Manchester, UK Controller bandwidths – RSC inner-loop RSC current controller d&q – 10Hz RSC d – 10Hz q – 120Hz ω r (pu) Torque (pu ) Vdc (kV)ir_abc (kA)

Power Conversion Group School of Electrical and Electronic Engineering The University of Manchester, UK Crow-bar protection Timed crow-bar applied for 0.4s Torque (pu ) Vdc (kV) ir_abc (kA) ω r (pu) Pitch angle (degrees) Minimum threshold crow-bar

Power Conversion Group School of Electrical and Electronic Engineering The University of Manchester, UK Controller coordination Torque (pu ) Vdc (kV) ir_abc (kA) ω r (pu) Pitch angle (degrees) Damping mode Damping controller setting

Power Conversion Group School of Electrical and Electronic Engineering The University of Manchester, UK Controller coordination Torque (pu ) Vdc (kV) ir_abc (kA) ω r (pu) Pitch angle (degrees) Damping mode Damping disabled during fault

Power Conversion Group School of Electrical and Electronic Engineering The University of Manchester, UK  Drive-train reliability can be deteriorated by torque ripples in –Wind speed changes –Grid fault  A DFIG wind turbine model (PSCAD/EMTDC) is implemented for simulation, improvement is achieved by bandwidths coordination –RSC current-loop controller adjustment –Pitch controller adjustment  Crow-bar protection and damping control coordination –Minimum threshold crow-bar –Damping control disabled during fault –Soft resumption of damping control after fault  Future work – natural flux weakening, fast Pitch, different Winds Summary