Font Size: a A A

The Control And Optimization For Islanded Microgrid With Wind Power

Posted on:2018-07-11Degree:MasterType:Thesis
Country:ChinaCandidate:B GeFull Text:PDF
GTID:2322330512477376Subject:Electrical engineering
Abstract/Summary:PDF Full Text Request
Under the pressure of environmental pollution and energy crisis,distributed generation including wind power,solar power and other renewable energy sources has become a research hotpot.The microgrid consists of distributed generation(DG),energy storage and load according to certain topology,therefore the development of microgrid is the key to the DG for the large-scale application.The microgrid can operate in both grid-tied mode and islanded mode,which is a great support to the power grid and improves the reliability of power supply and power quality.The problems caused by conventional droop control are studied in detail for the islanded microgrid with wind power in this master thesis.A novel method of online line impedance parameter identification based on PARK transformation is proposed for the unfair reactive power allocation which is caused by unmatched line impedance,then the identified line impedance parameters can be used to modify the reactive power droop slope.The validity and feasibility of proposed method is verified by the simulation and experimental results.Meanwhile,the small signal model of microgrid is built to analyze the stability of the system when the droop slope varies.The stability of the system is decided by the eigenvalue of the state-matrix.Secondly,aiming at the problems of unfair reactive power sharing mentioned above,an improved droop control strategy based on line voltage drop compensation is designed in this master thesis.To guarantee the same output voltage of DG and achieve the accurate reactive power sharing,the line voltage drop compensation is added to the conventional droop control,which can translate the droop characteristic curve.As the steady state errors always exist in the droop control,thus the secondary control is applied on the basis of primary control,which can restore the voltage and frequency to allowable range.Thirdly,an improved droop control based on adaptive DC bus voltage regulation is designed for the coordinate control of wind power and energy storage system in the microgrid.The droop characteristic curve is translated dynamically for the maximum wind power when the wind or load varies,and the insufficient power is compensated by energy storage system.Lastly,the negative sequence voltage suppression is employed for the three-phase unbalanced voltage of AC bus which is caused by three-phase unbalanced loads.By comparison between the double closed loop control and positive-negative sequence control of voltage and current in Matlab/Simulink simulation,it is approved that the proposed method can lower the unbalanced degree of AC bus voltage effectively.
Keywords/Search Tags:Microgrid with wind power, Islanded operation, Reactive power sharing, Wind power-energy storage system control, Negative sequence voltage suppression
PDF Full Text Request
Related items