Impedance Modeling and Stability Analysis of the Converters in a Double-Fed Induction Generator (DFIG)-Based System

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.

Modern Power System Dynamics, Stability and Control

“…Xunjun Chen et al [5] presented a harmonic stability analysis of doubly-fed induction generators (DFIGs) wherein it is taken into account the double pulse width modulation (PWM) converter, one of the main harmonic sources in 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.…”

Frequency-Coupled Impedance Modeling and Resonance Analysis of DFIG-Based Offshore Wind Farm With HVDC Connection

“…where the detailed expressions of A and B are given in Appendix A. For the power balance between the AC input and DC output of the RSC, the frequency domain smallsignal representation can be written as   (20) where (21) where the detailed expressions of…”

“…As for the impedance modelling of DFIG-based WT, most recent publications either have not incorporated the detailed double-loop PI control or neglect the DC side dynamics [17]- [19], which makes them incapable of capturing the exact low-frequency impedance responses of DFIG-based wind energy conversion system [20]. Additionally, the frequency coupling between the sequence impedances of DFIG-based WT are often neglected in stability analysis [2], [21], [22], which can lead to wrong judgement in the assessment of SSR stability [18], [20]. In order to accurately evaluate the risks of resonances for a wide frequency range, this paper derives a detailed impedance model of DFIG-based WT taking into account of all relevant control dynamics.…”

Remote Monitoring and Fault Diagnosis of Ocean Current Energy Hydraulic Transmission and Control Power Generation System

“…At present, the main technologies of sea current energy generation include permanent magnet synchronous generation [6], double-fed asynchronous generation [7], and hydraulic transmission and control generation. Among these technologies, permanent magnet synchronous generation and double-fed asynchronous generation are more mature and have been used in practice and hydraulic transmission is characterized by its flexible layout [8].…”

“…Alarm data management: The upper and lower limits of the alarm value are set for specific variables, such as the liquid level and pressure of the hydraulic transmission and control power generation system; (5) Remote control function: Remote start/stop and parameter setting function for the oil replenishment and hydraulic station systems; (6) Fault diagnosis function: Fault diagnosis of the system's normal operation, and failure of the accumulator, relief valve, hydraulic motor, and hydraulic pump, via a combination of the hydraulic transmission and control remote monitoring system and the proposed improved fault diagnosis model; (7) Data query function: The data query system is implemented using a database, in which the type and time of each failure are stored, and all information relating to previous failures in the system can be accessed via a query.Energies 2021, 14, x FOR PEER REVIEW 7 of Fault diagnosis function: Fault diagnosis of the system's normal operation, and failure of the accumulator, relief valve, hydraulic motor, and hydraulic pump, via a combination of the hydraulic transmission and control remote monitoring system and the proposed improved fault diagnosis model;(7) Data query function: The data query system is implemented using a database, in which the type and time of each failure are stored, and all information relating to previous failures in the system can be accessed via a query.…”