Abstract
Harmonic stability of double-fed induction generators (DFIGs) now has become a significant topic because of its harmful impact on power quality issues of the system. Since the double pulse width modulation (PWM) converter is one of the main harmonic sources in DFIGs, it may cause harmonic instability with increasing harmonic contents. Thus, the modeling and stability analyses of PWM converters in DFIGs are essential steps to assess the harmonic stability of DFIGs. Aiming at dual PWM converters, which include the grid side converter (GSC) and the rotor side converter (RSC), this paper divides converters into two parts: circuit modules and control modules. Closed-loop input impedance models of each module are then derived by means of transfer functions. Hence, the stability of the system can be readily predicted through Nyquist diagrams. The contributions of parameters to the system’s harmonic stability are also identified. Finally, time-domain simulations are conducted in a real-time digital simulation (RTDS) system. Simulation results confirm that the established impedance model can effectively reveal the stability of the DFIG-based system and can give critical conditions for the occurrence of harmonic instability.
Highlights
When it comes to wind power generation, a double-fed induction generator (DFIG) is a more advanced and ideal technology in wind generation development
These advantages are based on double pulse width modulation (PWM) converters, which are widely used in DFIG systems for their independent control of reactive power at both sides
In order to analyze the stability of a DFIG-based system, two effective system-level methods have been proposed for stability analyses: a time-domain eigenvalue analysis based on the state-space model and an impedance-based analysis based on the transfer functions in the frequency domain [7,8,9,10,11,12,13]
Summary
When it comes to wind power generation, a double-fed induction generator (DFIG) is a more advanced and ideal technology in wind generation development. Different from an eigenvalue analysis approach, an impedance-based analysis can assess system stability without prior knowledge of system parameters This allows the modeling of converters to turn. An impedance model based on transfer functions of inverters in a system was established by impedance modeling to study the harmonic resonances and dynamics of three-phase power system was developed. Previous works and papers lacked converter modeling that includes controlwhich systems with the lock loop (PLL) isMoreover, often overlooked; focus on the macro modeling of DFIGs, is useful for phase system-level analyses. Converter modeling that includes control systemsstability with thecannot phase lock loop (PLL) is often overlooked; order parametric to fill this gap, this paper attemptsstability to utilize an impedance-based ,In specific influences on harmonic cannot be predicted. Figure depicts the DFIG-based systems and formulate detailed models of RSC and GSC with means of transfer functions
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