Study On Power Supply By Load Classification Of Microgrid In Pastoral Areas

There are vast pastoral areas in Western China.Because of the dispersed production mode of nomadic people and the extremely low population density,the construction cost of power grid is extremely high.Because of the difficulty of power supply in many areas,the economic development is seriously restricted.In the past,small DC generators have been used to supply power to DC loads,but the power is limited,and the type of load is severely limited,so it is impossible to use production machinery such as AC motors.In the previous period,the state invested a lot of money to make some pastoral areas connected to the power grid,which greatly improved the electricity consumption situation in pastoral areas.However,there are some problems such as high construction and maintenance costs,unstable voltage,and easy to break down and difficult to repair in time.The emergence of Distributed Renewable Energy provides conditions for isolated power supply of microgrid in remote areas.In pastoral areas,islands,mountainous areas with complex terrain and unmanned areas where conventional energy shortage is difficult to cover,renewable energy such as wind power and photovoltaic power can be used to supply electricity,which improves local production and living conditions.In the power supply system with renewable energy as the main body,it is very difficult to realize the stability of the system because of the strong random fluctuation of the power supply side and the load side.Therefore,the isolated network of microgrid must be equipped with certain energy storage devices to balance the peak and trough of power consumption.However,it is not economical to equip large capacity energy storage devices in small isolated microgrid power supply system.However,according to the demand for electricity and load characteristics,the generating power and load can be adapted as far as possible to reduce the capacity of energy storage devices.There are many types of household electrical appliances.Different types of loads have different electrical characteristics.Therefore,different types of loads can be supplied separately to ensure the quality of power supply for important loads.In this subject,the micro-grid uses wind power,photovoltaic,energy storage combined power supply,andadopts the way of power supply according to load classification.Considering the economy,wind power is the main and photovoltaic is the supplement.The power generated by wind turbines is divided into two parts,one is to supply power frequency loads and energy storage components through power electronic converters and DC micro-grid systems,the other is to supply electric heater loads and energy dissipation loads.According to the importance of loads,the power supply can be realized according to different priorities.This power supply mode reduces the power through DC microgrid and power electronic conversion devices,reduces the energy storage capacity,and ensures the reliability of the whole system.The energy storage unit is composed of lead-acid batteries and supercapacitors.The system also makes full use of wind power resources to achieve thermal energy storage.In the DC micro-grid part of the system,the DC bus connects the distributed generators and energy storage units,eliminates the differences among the micro-power sources,unifies the power standards of the micro-power sources through the necessary interface conversion circuit,and ensures the voltage stability of the DC bus.The system is controlled by PLC,and the related voltage,current,frequency and power of the main components are controlled to ensure the stability of the system.