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AALBORG UNIVERSITY INSTITUTE OF ENERGY TECHNOLOGY. Evgen Urlep. December, 2002. UNIVERSITY OF MARIBOR INSTITUTE OF ROBOTICS. Control of Three-phase Active Rectifier for Wind Turbine Applications. Contents. Introduction System modeling and analysis LCL filter design Control design
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AALBORG UNIVERSITY INSTITUTE OF ENERGY TECHNOLOGY Evgen Urlep December, 2002 UNIVERSITY OF MARIBOR INSTITUTE OF ROBOTICS Control of Three-phase Active Rectifier for Wind Turbine Applications
Contents • Introduction • System modeling and analysis • LCL filter design • Control design • Simulation and implementation • Conclusion
Introduction Types of Wind Turbines • Horizontal axis • Vertical axis Operation modes of WTG • Constant Speed – Constant Frequency • Variable Speed – Constant Frequency
Nominal power 11kW Nominal grid current 16A Grid side phase voltage (rms) 230V Grid frequency 50Hz Rated values DC link voltage 700V DC link nominal current 17A Problem definition Design and implementation ofthe control scheme for the DC/AC converter in WTGin • Grid connection • Stand-alone
Three-phase Active rectifier RL-filter
Grid connected Active Rectifier control structure
LI [mH] 1.25 LG [mH] 1.5 CF [F] 6 RD [] 4 LCL filter design Qc<5% ZT<10%Zb res<0.5sw
Kp=4.8 Ti=8 ms Root locus
DC-link controller design CDC>>(Tei+0), optimal symmetry criterion kDC=0.7, Tet=4.8ms
Kp=0.35 Ti=20 ms Root locus
Stand-alone Standalone control structure
Kp=0.1 Ti=0.29 ms Root locus nominal load 1% load
DC-link voltage limiter Tet=2.1ms, 0=0.2ms CDC>>(Tei+0), optimal symmetry criterion
Kp=0.79 Ti=0.092 ms Root-locus
Kp=80 Ti=1 s Phase angle detection
Steady state simulation Grid mode Generating mode Ideal phase voltage 2% 5th + 1% 7th harmonics
Steady state simulation Stand-alone mode phase voltages and current at nominal power using resistive load
Transient simulation Stand-alone mode System startup Half of nominal load to nominal load
Implementation dSPACE 1103 MPPC 604e at 633Mhz TMS320F240 16xADC-16 4s ±10V 4xADC-12 800 ns 10V 8xDAC-14 bit -6 µs 10 7x IE interface 32xI/0 TDE software
Measured conditions UDC=650V UAC=220V P=11.28kW PF=0.998 ITHD=6.7% UTHD=2% Steady state operation Grid mode Rectifying mode Generating mode
Transient operation Grid mode Nominal load system startup Disturbance rejection
Measured conditions UDC=700 V UAC=230 V P=11 kW IAC=16.4 A ITHD=3.4 % UTHD=3.4 % Steady state operation Stand-alone mode Resistive load
Measured conditions UDC=700 V UAC=230 V P=11 kW IAC=16.6 A ITHD=25 % UTHD=10 % Steady state operation Stand-alone mode 3-phase diode bridge
Transient operation Stand-alone mode Full load applied on the half of produced power
Stand-alone mode Transient operation Short-circuit startup
Automatic mode switch Idle mode I-SA I-GM GM-I SA-I Stand-alone mode Grid mode GM-SA I-GM:UG and /PLLe and /TRIP and START I-SA:/UG and /TRIP and START GM-I: TRIP or STOP SA-I: TRIP or STOP or PLLe GM-SA: PLLe
Grid mode to Stand-alone mode transition nominal load
Conclusion • Vector based control of DC/AC converter with near unity power factor was succesfully designed, simulated, implemented and verified. • LCL filter was designed, implemented and tested • Two different control strategies were implemented according to the operating modes • A common controller design procedure is used to tune controller parameters • PLL is designed to detect phase angle • Two different control strategies are implemented and tested in dSPACE. • Automatic mode detection and switching betwen modes can be implemented