Research On The Strategy Of Short-circuit Current Limiting For The Large Receiving-end Grid

The separation between electric energy and load center make China power grid presents characteristics between sending end and receiving end. With developing of the scale of Ultra-High Voltage transmission system, the electric distance of the system is shrinking, electric networks is intensifying, short-circuit current is consequently increasing year by year, which has become a serious problem for the planning and operation of power system. How to limit the current under a reasonable value has been the most urgent affairs.With the proportion of receiving end grid internal power supply gradually reduced, the system become more inseparable. The short-circuit current shows the following characteristics:individual site excess and regional sites excess. The paper study against these characteristics and reach different limiting measures for different circumstances.Based on analyzing and comparing the basic principles and traits of the different methods of limiting short-circuit current, the paper summarized the principles, application features and applicability for power grid of different methods firstly. In order to solve the problem of short-circuit current excess of individual site, the paper build self-impedance model to analyze the mechanism of its excessive, drawn optimized selection model of limiting measures based on grid network parameters. It is proved that the methods is valid and which high practicability by utilizing in a power grid in China. Finally, the paper analyze the reasons for the uneven distribution of short-circuit current of the problem of regional sties excess, summarize the characteristics of different partition mode to limiting current, an optimization algorithm base on the Entropy weighted decision theory is proposed, it is proved that the methods is valid and which high practicability by utilizing in a power grid in China.