Design and Comparison of Auxiliary Resonance controllers for Mitigating Modal Resonance of Power Systems Integrated with Wind Generation
Abstract : Full converter-based wind power generation (FCWG, e.g., a permanent magnet synchronous generator (PMSG)), though normally considered to be decoupled from the external power grid can be actuated as an inertia source to suppress modal resonance in wind generation penetrated power systems by installing auxiliary resonance controllers (ARCs). In this paper, three possible options for ARC installation are first identified based on some derivations of the conventional control model of FCWG. The damping support mechanism of ARC is revealed, a suitable and generic configuration structure of ARC is then established, and optimal parameter tuning is conducted on the basis of this ARC configuration. The three ARC alternatives are equipped to contribute to damping by utilizing the potential energy and dynamics hidden in different inertia source components (i.e., the wind turbine rotor and DC capacitor, respectively) of FCWG. Both modal analysis and simulation results validate the effectiveness of the three proposed ARCs in suppressing modal resonance and improving system oscillation stability. Most importantly, extensive comparison investigations are carried out to fully evaluate the pros and cons of the three ARCs and thus provide constructive application guidance for system operators and wind farm owners.
? This paper discusses issues related to the integration of wind farms in the power system, such as maximum power point tracking, fault ride-through capabilities, interarea and subsynchronous oscillations, and voltage flicker, and provides a review of the existing control strategies to address these issues in Types I, II, III, and IV wind turbines.
? A comprehensive review of existing supplementary control approaches for wind energy systems.
? The potential advantages and disadvantages of the existing supplementary controllers to improve the MPPT and LVRT capabilities and mitigate SSR and voltage flicker for a Type I wind system.
? FCWG is responsible for modal resonance for two reasons: 1) the detrimental modal resonance may occur due to improper parameter setting of FCWG or unexpected operating conditions and 2) modal resonance may not only jeopardize the system damping but also affect the dynamic performance of FCWG itself, which may incur a critical trip or asset damage and hence considerable economic losses related to wind farms.
? In traditional power systems dominated by thermal power, if the system damping is not sufficient then conventional synchronous generators (CSGs) can be equipped with damping controllers (such as power system stabilizer (PSS)) to provide damping support for the power system
• On this basis, a modal shift evaluation (MSE) method by using bilateral damping torque analysis is proposed to accurately quantify the interaction effect of POMs and EOMs on each other and effectively explain their complex interaction process.
• A general theory of interaction of eigenvalues is proposed in, where the strong and weak interactions are identified with their geometric interpretation on the complex plane.
• The resonance excitation index (REI) is also proposed to imply the intensity of modal interactions and plays as a valuable tool in the MIO.
? To achieve better dynamic performance as well as maximize the capture of wind power, wind farm owners normally adopt conservative control strategies instead of providing damping support for the external power system.
? Therefore, FCWG may be viewed as a favorable renewable energy but its contribution to power system oscillation stability is normally considered to be weak or even negative.
? PLL releases its angle signal to other parts (e.g., GSC) and guides the synchronization of FCWG, and thus its output plays an important role in the overall performance of FCWG.
? The parameters of ARC have key importance on the performance in damping support, and thus should be carefully tuned.
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