| With the continuous development of China’s power grid,the scale of power grid continues to expand,and gradually form a special high-pressure as the backbone of the grid power network.UHV power grid has large scale,long transmission distance and large transmission capacity,which leads to the rapid increase of short-circuit current level of power grid after UHV access,and has wide influence.Aiming at the problem of short-circuit current exceeding the standard of UHV access to Jiangxi power grid,this paper studies the calculation of short-circuit current and the limiting measures.This paper analyzes and calculates the short circuit problem of the planned UHV access to Jiangxi power grid,and finds out the problems in the short circuit of Jiangxi power grid.With the continuous strengthening of the grid structure of Jiangxi power grid and the increase of the generator set,the electrical distance is reduced,the short circuit current level in the network is getting higher,the short-circuit current of most factory and station switchgear has exceeded the occlusion capacity of the circuit breaker,and the problem of short-circuit current exceeding the standard in the load concentration area has become an urgent problem Therefore,in order to carry out the construction of UHV engineering,it is necessary to calculate the short-circuit current of the planned power grid network frame,and take corresponding measures to meet the requirements of the system can operate safely and stably after UHV access.In this paper,an optimal configuration method of current limiter based on the reliability of power network is proposed.Aiming at the reliability analysis under shortcircuit current,the quantitative model between reliability evaluation and short-circuit current is established by short circuit calculation and related electrical quantity acquisition,and then the current limiting device is optimized to point,reduce the range of optimized cloth point,simplify the calculation process and shorten the optimization time.Aiming at the actual power grid in Jiangxi Province,by establishing the reliability analysis model and combining with the corresponding simulation calculation,the position of low dynamic reliability is mainly in Nanchang area,therefore,when the installation of the current limiter is analyzed,it can be optimized for different evaluation results to achieve the goal of effectively limiting short-circuit current.Combined with the calculation of shortcircuit current in Jiangxi power grid and the analysis of the corresponding grid structure,firstly,the dynamic reliability of Jiangxi power grid is evaluated,the range of the current limiter is reduced,the feasible current limiter layout scheme is put forward,and the main installation line is Yongxiu-Nanchang when a current limiter is installed.The main lines for installing two current limiter are Yongxiu Nanchang-Jinxian;The main lines for installing the three current limiter are Yongxiu-Nanchang,Yongxiu-Mengshan,Changte-Jinxian.The number of current limiting device mounting table is different,its current limiting effect has a great difference,according to the requirements of different current limit margin,you can choose the appropriate number of current limiter mounting table.This paper analyzes and calculates the short-circuit exceeding the problem after the UHV access to the provincial power grid,and provides a reference for the structural planning and current limiting measures of the large power grid. |
