Study Of Transmission Section Fast Search And Active Power Correction For Preventing Cascading Overload

With the growing demand for electricity, regional and long-distance transmission network systems have emerged, exacerbated by the complexity of the network size. The frequent occurrence of blackouts caused enormous social and economic losses, become a potential threat to people’s normal production and life. Rapid identification system overloaded trend of regional power, to take prompt and effective control measures to ensure the safety and reliability of power supply in the region has become an important research topic in power system stable operation. At the same time, the new energy grid has become a major trend in the future, flexibility and randomness of new energy power generation to the grid security will also bring new challenges.With the reasons of some typical blackouts are analyzed, it is pointed out that the power flow transferring caused by overload removal and the unreasonable action of protection devices are the important reasons to cause the accidents worse. Seen by the system as an equivalent DC networks, it is to analyze the features and paths of flow transferring.The target for the security analysis of overload to whole system is reduced to the analysis of a transmission section. A new algorithm for fast searching transmission section based on FLOYD. In the topological graph of the power system, it finds out the K shortest paths between the two nodes of the overload line, and according to the trend direction and flow transferring factor of each line, then finds out the identify branches constitute transmission section. For further enhance the search speed, it is by forming the generalized grid topology to reduce the search areas based on BFS algorithm. IEEE30-bus system to verify the correctness and effectiveness of the algorithm in the transmission section of the search.It is judged that when overload occurs, the effect of overload removal to threat other lines security, emergency control measures must be taken to eliminate the overload. An algorithm of corrective control based on sensitivity is present to deal with overload of transmission lines, the integrative sensitivity characterizes that each node has the ability ofeliminating overload, and according to the adjustment method of reverse and equivalent match and heuristic rules to define the operation sequence of control nodes. Because of the limitations of traditional heuristic rules, the generalized heuristic rules is proposed, which is proved by IEEE30-bus system to had more broad application prospects than traditional heuristic rules.Distributed generation to the grid brings a new impact on fast searching transmission section and corrective control, DG changes the trend direction and the number of active generations in the system.In order that distributed generation plays a more active role in grid security, given the principle of selecting DG, and strives for DG to the grid more theoretical basis.