Real-time dc-link voltage control of 5-kW PMSG-based wind turbine generator through a test-rig

Abstract

In this work unlike the usual grid side converter, the machine side converter is considered to control the dc-link voltage of a permanent magnet synchronous generator-based wind turbine generator. For this purpose, a discrete real-time laboratory test-rig is prepared for real-time application of the system. In the real-time test-rig, 5-kVA permanent magnet synchronous servo motor is driven by Unidrive SP variable frequency drive to emulate a standalone wind energy conversion system; GUASCH converter as a machine side converter and for implementing the designed PI controllers using pole placement technique combined with a symmetrical optimum criterion for real-time control of the dc-link voltage transient changes, Texas instrument TMS320F28069 digital signal processor discrete real-time microcontroller control card in a GUASCH board are used. Moreover, a simulation model of the system is prepared in MATLAB Simulink user-defined function blocks considering the dynamic mathematical equations of every part in the system. Achieved simulation and real-time test-rig results show that the designed dc-link voltage control of the system works properly at different transient load changes connected to the standalone WTG and dc voltage reference value changes. Moreover, the simulation results are properly validated by the real-time test-rig results and the PI controller designed using pole placement technique combined with a symmetrical optimum criterion method was ideal.

Appendix

$L_d$	Rotating field d-axis inductance
$L_q$	Rotating field q-axis inductance
$R_s$	Winding resistance
$K_T$	Torque constant
$\varPsi _\mathrm{pm}$	Flux linkage of permanent magnet rotor
$V_d$ $V_q$,$i_d$,$i_q$	Stator d-axis, q-axis voltages and d-axis, q-axis current
$\omega _e$	Electrical speed of the rotor in (rads/s)
$T_\mathrm{S}$	Sampling time
$T_\mathrm{d}$	Delay introduced by the digital calculation of the current control loop
$T_\mathrm{DC}$	Delay introduced by the digital calculation of the converter
$T_\mathrm{m}$	Time constant of the machine
$T_\mathrm{disum}$	Over all time delay of the current loop
$\omega _{n}$	The natural frequency
$\zeta$	Relative damping
$P_\mathrm{dq}$	Active Power in dq0 axis
$Q_\mathrm{dq}$	Reactive Power in dq0 axis
$e_{d}$	Back emf in d-axis
$e_{q}$	Back emf in q-axis
$i_\mathrm{dc}$	DC current
$V_\mathrm{dc}$	DC-link voltage
$i_\mathrm{c}$	DC-link Capacitor current
$i_\mathrm{L}$	Load current
$T_\mathrm{dV}$	Delay introduced by digital calculation for dc-link voltage
$T_\mathrm{eqi}$	Delay of the inner current control loop
$T_\mathrm{Vsum}$	Over all time delay of the dc-link voltage loop
$G_\mathrm{pv}$	DC-link voltage loop proportional gain
$T_\mathrm{iv}$	DC-link voltage loop integral time
$G_\mathrm{pi}$	Inner current loop proportional gain
$T_\mathrm{ii}$	Inner current loop integral time