Research On Power Grid Emergency Frequency Control With Wind Power And DC

In modern power systems,the increasing installed capacity of wind power and the rapid development of high-voltage direct current(HVDC)transmission technology bring great benefits,meanwhile these also cause a number of safety and stability problems to the power grid,such as Large-scale wind power trips,HVDC latching,etc.,all these pose new challenges to the emergency frequency control of the power grid.At the same time,in the current power system,resources that can participate in emergency control(emergency frequency control resources)are gradually diversified,such as traditional generator,wind power,HVDC,etc.,but their performance,price,etc.,are significantly different.Therefore,in order to improve the grid emergency frequency control performance,it is particularly important to study the coordinated control of these resources.The main research contents and results of this paper are as follows:1.Based on the power system simulation software DIg SILENT/Power Factory,a typical two-region simulation system for wind power delivered by HVDC is built.The analysis and derivation of the basic structure and mathematical model of the thermal power unit,doubly-fed induction generator(DFIG)and HVDC,and using the DIg SILENT/Power Factory software to build three simulation models.Based on the built simulation system,the control characteristics of the frequency of the thermal power unit,DFIG and HVDC are studied.2.The influence of the operation speed of different emergency frequency control resources on the system frequency is analyzed and studied.For emergency control measures such as HVDC emergency power support,fast shut-off valves,and cutting machines,the basic principles and control models of each control measure are analyzed.Based on the deduced power system frequency response model and the active power speed model of the resource,the control effects of different emergency control measures on the system frequency are analyzed and studied.Research shows that the faster the operation speed of emergency control measures,the more effective the system to slow down the rate of increase in frequency and reduce the peak frequency.Finally,the correctness of the above research is verified by simulation.3.An emergency frequency control strategy is proposed for power grids containing single types of emergency frequency control resources(single measures)and multiple types of emergency frequency control resources(multiple measures).Based on the established system active energy surplus model and resource equivalent active removal model,a single resource emergency control strategy that takes into account the operation speed of resource is proposed.This strategy can accurately calculate the amount of equivalent active power removal and control the system frequency peak according to the system target threshold.Then,based on the adjustable capacity of the resource and its cost,the system's active resource allocation strategy for the priority of continuous resources is determined.On this basis,a multi-resource emergency coordination control strategy that takes into account the adjustable amount of resources and the operation speed of movement is proposed.The simulation results show that the proposed emergency control strategy can accurately calculate the equivalent active energy removal amount of the system so that the system frequency peak value is controlled below the target threshold,effectively improving the dynamic frequency performance of the power grid under emergency conditions.