Research On Harmonic Resonance Of Off-Shore Wind Farm Based On Modal Approach

The offshore wind power is becoming an important development direction in the field of wind generation.Due to the wide application of power electronic devices,the impact on power quality of harmonic generated by wind turbines and transformers is no longer an ignorable problem.In offshore wind farm,submarine cables are widely used to transmit power,which makes the resonance problem more serious due to the cables' high grounding capacitor.The power collecting system determines the cables' length,electric parameter and connection type,which directly affects the resonance frequency and impedance.Modal analysis method can pinpoint the critical nodes and element about resonance which make it an effective approach for analyzing offshore wind farm resonance.This thesis built the resonance model of offshore wind farm transmission system,including wind generators,cables and transformers.Using modal analysis method,the resonance situations under different power collecting systems are simulated and calculated.The key nodes causing resonance are located by the participation factor.The main parameters' influence on resonance are evaluated with parameter sensitivity analysis.Finally the filtering solution is proposed for different resonance frequency,which is proved to be effective by simulation results.In this thesis,a complete analysis approach for offshore wind farm harmonic resonance was proposed.And it can provide reference of power collecting system for the early designing stage of offshore wind farm,or of filtering devices' installed location and parameters for the offshore wind farms have been built.