| The power system is the foundation of a country's economic development,and the security and stability of the power system is an important criterion to measure a country's comprehensive national strength.The tragic lessons of countless power accidents around the world tell us that once the power system is seriously damaged,the huge economic losses and serious consequences are unpredictable.With the continuous increase of electricity consumption in all walks of life in today's society,the development and utilization of power grids has become commercialized and diversified,and the resulting problems of power system's stability are also on the rise year by year.All indicates that more in-depth discussion of the mechanism of power grid's stability,continuous development of analysis methods of more effective power grid's stability,and summing up both economic and applicable power grid's control schemes,all of which will become an important issue that every power user needs to face nowadays.On the entry point of grid connection scheme of Jixi Thermal Power Plant's expansion project,the security and stability of access to grid are analyzed in this paper.There are 6 provincial power plants in Jixi Power Supply Zone,with a total installed capacity of 1270.4 MW,including 2 thermal power plants with installed capacity of 850 MW and 4 wind farms with installed capacity of 402.4 MW.Because of insufficient heating capacity and increasing heating load in this region,it is urgent to add heating units to solve this problem.The increase of new units will inevitably bring new challenges to the original weak power grid.The grid-connected operation of Jixi Thermal Power Plant's expansion project will affect voltage quality and power flow distribution of the grid,and even have a huge impact on the security of the overall grid in Jixi.Therefore,it is of important research significance and engineering value to analyze the security of access to grid of Jixi Thermal Power Plant's expansion project.This paper analyzes current situation of power balance and power grid in Jixi and the whole province.From the view of changing district heating structure,improving district heating efficiency and reliability of power supply,this paper expounds the necessity of the construc tion of Jixi Thermal Power Project,and puts forward some solutions to the problems that may arise in the process of access to power grid.Then,this paper do researches and analyses on the static security and stability of Jixi Thermal Power Plant after its expansion project is connected to the power grid.Firstly,the basic conditions of power flow calculation are set according to actual situation,and the analog computation and analyses on faults of "N-1" under normal mode and maintenance mode are carried out.The potential safety hazard of static security of Jixi power grid are put forward,and the specific solutions are given.The results are checked and analyzed to verify the simplicity and reliability of the solutions.Lastly,the transient safety and stability of Jixi Thermal Power Plant after its expansion project is connected to the power grid are studied and analyzed in this paper.Firstly,several mathematical models commonly used in the transient analysis of Hei Longjiang power grid are given,and the common operation modes and faults are set.Through the power flow calculation on the fault of single circuit line,main transformer and 220 kV double busbar's primary circuit repair and clearing out of secondary circuit‘s fault,the resistance of Jixi Power Grid in the face of large disturbances or complex faults are analyzed,and the corresponding effective measures are given separately for the problems found in the study.The results of analysis show that the excitation regulation of the generator unit can ensure the transient stability of system in the case of slight or general faults,and provide reference and basis for how to deal with similar faults in the regional power grid when they occur again. |
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