Study On Droop Control Strategy Of Rural Low-voltage Microgrid

With the rapid development of China’s economy and the sharp improvement of people’s living standards,the demand for electricity has increased substantially,which has required a lot of construction and improvement of the power grid.Especially in rural areas of China,with the construction of new countryside,the power consumption has increased rapidly,the previous power grid has been unable to meet the user’s demand for electricity,which often leads to insufficient power supply and unstable voltage.Especially for remote rural areas in geographical location,the terrain is not flat and the transportation is inconvenient,and there are many technical problems in transforming the power grid.Therefore,the combination of microgrid and large power grid can be used to solve the problem of insufficient power supply and unstable power supply,so that we do not need to change the original large power grid.The combination of microgrid and large power grid requires the use of appropriate control strategies to enable it to output a stable voltage.Therefore,it is of great significance to study the control strategies of microgrid.First,according to the characteristics of microgrid that uses wind,solar,geothermal and other distributed generation to generate electricity and its output voltage is greatly affected by the natural environment,a voltage-controlled bidirectional DC / DC converter with a battery is designed to stabilize the DC side voltage of the microgrid to ensure the stability of the AC side voltage of the inverter.Then,based on the analysis of the traditional droop control principle and power transmission characteristics,the reason why the rural low-voltage microgrid’s reactive power was difficult to distribute in proportion was revealed.After the traditional droop controller,a voltage current double loop controller was introduced,which effectively stabilized the output voltage and was verified by simulation.Considering that the line impedance of the rural microgrid is resistive,so that traditional droop control cannot achieve power decoupling,this paper presents a virtual impedance droop control strategy to reduce the resistance-to-inductance ratio and achieve the purpose of power decoupling.Finally,aiming at the voltage drop caused by the introduction of virtual impedance,this paper presents a dynamic voltage compensation method for the rated voltage.In order to verify the effectiveness of the proposed method,using MATLAB / Simulink to build a dual micro-source microgrid simulation model and analyze it.Simulation results show that the output voltage and frequency of the low-voltage microgrid in rural areas can be maintained stable after adopting a virtual impedance droop control strategy with voltage compensation,and the power can be equally divided without large voltage drop.