Research On Adaptive Coordinating Under Frequency And Under Voltage Load Shedding Method Considering Demand Side Resources

With the continuous development of society and economy,the scale of China’s power system is constantly expanding,and the power grid structure and regional electrical connections are becoming more and more complex,which brings great challenges to the safe and stable operation of the power system.In recent years,large-scale power outages have occurred throughout the world,which have severely affected economic development and the improvement of people’s quality of life.Under frequency load shedding(UFLS)and under voltage load shedding(UVLS)measures,as the last line of defense of the power system,have played an important role in avoiding large-scale power outages and ensuring the safe and stable operation of the power grid.With the continuous development of demand side management technology,demand side resources play an important role in ensuring the power quality and economic operation of the power grid due to its higher regulatory flexibility.Therefore,this paper focuses on the power reduction potential of demand side resources under low-frequency and low-voltage conditions,aggregates scattered demand side resources,and studies its coordinated control strategy for participating in under frequency and under voltage load shedding.The main tasks as follows:Firstly,the frequency and voltage characteristics of the power system are studied,and the basic theory of under frequency and under voltage load shedding and the traditional setting methods are studied on this basis.Secondly,the models of air-conditioning aggregation,photovoltaic power supply and the energy storage device are established.The coordinated control methods of demand side resources under low-frequency and low-voltage conditions are studied.These coordinated control methods can reduce the impact on users while effectively regulating demand side resources.Then,on the basis of studying the frequency and voltage characteristics of the power system,the adaptive UFLS and UVLS strategies and methods are studied.Based on the system frequency and the bus voltage,the power deficit is calculated and load shedding action parameters are set.And the optimal load shedding scheme is matched through the improved implicit enumeration method based on the bus voltage sensitivity.This method can effectively improve the speed and accuracy of load shedding actions in emergency situations.Finally,an adaptive coordinating UFLS and UVLS method considering demand side resources is proposed,which is based on the adaptive load shedding method.Through the orderly regulation of demand side resources,this method can effectively suppress the sharp drop in frequency and voltage after the power system is disturbed,reduce the amount of actual load shedding,eliminate the risk of frequency and voltage collapse earlier with minimal control cost,improve the initiative of the grid,and effectively guarantee the safe and stable operation of the power grid.