A Study Of HVDC Harmonics Impact On Wind Farm

The study of this research work focuses on a comprehensive harmonic resonance analysis in a wind farm and investigates disturbance that arises due to HVDCs,influence on wind farm.The fundamentals of the offshore wind farm installation and basics of harmonic are first described.Additionally,the equivalent harmonic models of different components of wind farm is calculated to make resonance analysis clear.Modelling of system under harmonic conditions involve impedance calculation at harmonic frequencies,as well as the representation of the harmonic sources.Based on the vector control doubly fed induction generator(DFIG),a suitable model of offshore wind farm is built and validated in PSCAD/EMTDC.Matlab tools is used for more depth study of resonance phenomena.Linearizing the inverters effect,harmonic impedance calculation is made simpler before in-depth analysis of impedance resonance calculation at PCC of windfarm.The controller and protection of power system will operate normally by setting harmonic currents at few amperes as compared to the fundamental frequency current.Consequently we are able to see the effects of harmonic current injection at PCC from grid side without the interference of converter.Based on simulation model,frequency scan method is used to calculate harmonic resonance impedance at PCC of wind farm.Furthermore we evaluated the influence of various parameters(number of wind turbine units in operation,transformer and cable parameters selection)on the resonance frequency points.Lastly,a C-type high pass filter,hybrid filter and control schemes are designed,which lessened harmonics disturbances.