A Study Of Microgrid Power Quality Control Strategies Based On ES And DVR

With the rapid expansion of the installed capacity of renewable energy and the gradual expansion of the scale of micro-grid construction,resulting in renewable energy-rich areas of limited access to the grid,abandonment of light,wind and other problems are increasingly prominent,and the accompanying power quality problems cannot be ignored.Therefore,it is of great research significance to improve the penetration rate of renewable energy,ensure the system's capacity for renewable energy,improve the microgrid's utilization efficiency for distributed power equipment,and improve the power quality and reliability of the microgrid.A micro-grid environment where silos operate requires the setting up of a reasonable power structure and operation.According to the characteristics of the battery and photovoltaic power supply,the control methods of the main power supply and the slave power supply were designed respectively.Using the characteristics of the battery can store electrical energy,it is used as the main power supply to provide the standard value of voltage and frequency for the system;for photovoltaic cells that are greatly affected by light and temperature,the MPPT control method is designed to improve its utilization and use as a slave power supply.For the micro-grid in photovoltaic,wind power and other micro-power output has the randomness and uncertainty,in independent operation to the voltage and frequency support capacity is poor characteristics.One is to propose a power spring control method to solve the voltage and frequency fluctuations caused by the power imbalance.First,the principle of electric spring(ES)is analyzed and a mathematical model is derived;based on this,a topology of power spring with Z-source network structure is designed,and a microgrid voltage and frequency control method based on simplified emotional control is designed for this ES.Second,after a detailed analysis of the DVR's operating principle,control method,and voltage compensation method,the structure of the dynamic voltage restorer with Z-source network and its control method were designed to solve the load-side voltage fluctuation problem.On the basis of the above work,a power quality control strategy is designed,which integrates the coordinating role of system power imbalance and power output to suppress independent grid power changes and achieve frequency stability control of independent microgrids.For the problems of voltage and frequency,a microgrid control strategy for ES and DVR linkage is designed,and simulation experiments are carried out to verify the effectiveness of the structure and control method proposed in this paper.