Research On Power Quality Improvement Methods In Micro-Grid

In recent years,with the rapid development of power grid,new energy and environmental-friendly power grids have gradually become the research hotspot of power system,and micro-grid have become an important research direction.In the process of its development,the primary purpose is to ensure the stable operation and high quality power,can make it in the process of development gradually expand the scale,so the research on micro grid power quality improvement method is particularly important.Due to the special nature and structure of the microgrid,the intermittent and power fluctuations of wind power and photovoltaic power generation,and a large number of power electronic devices have brought great challenges to the safety,stability,and high-quality operation of microgrids.In order to ensure the efficient,safe and stable operation of the microgrid,it is necessary to conduct corresponding research on its power quality issues and propose effective solutions to meet the increasingly stringent power requirements of users.This article mainly focuses on two aspects of micro-power characteristics and grid-connected inverter technology,and active power filter(APF)in micro-grid power quality.This paper studies the working principle of the micro-grid,through the characteristic analysis of voltage flicker,frequency deviation,harmonic power quality issues,etc.In the case of the power problem of the micro-power source,the device is controlled by a Virtual Synchronous Generator,which is the same as the traditional Generator,which can be used to regulate the voltage and frequency of the system,and then,by using the prejuxtaposition control,to adjust the phase and amplitude of the output voltage of the inverter before the parallel grid,and then the entire system is integrated into the power grid,and it avoids the impact current of the parallel grid,and the power quality of the micro-power source is improved.Then,considering the coupling between the micro grid and the large power grid and the internal power quality problems caused by the nonlinear power electronic devices,especially the harmonics not only reduce the power quality level,but also harm the stable operation of the micro grid,therefore,it is of vital importance to improve the power quality of the micro-grid.Mainly is to study the harmonic current detection,because the traditional Least Mean Square(Least Mean Square,LMS)algorithm can not considering steady precision and fast convergence,therefore is proposed in this paper an improved LMS harmonic detection algorithm,the N time the error value and N+1 time value of the ratio of the Square as a feedback control signal,through the feedback signal to adjust the step length,successfully solves the original algorithm cannot be achieved at the same time the contradiction of fast convergence and high steady precision,simple control,excellent dynamic performance,better tracking precision,at last the algorithm was applied to the APF.Through the simulation analysis of Matlab/Simulink,the effectiveness and feasibility of the inverter VSG control strategy and the APF control strategy based on improved LMS algorithm are verified to improve the power quality of the micro-grid.