DC Dropping Location Selection Method Research In Multi-infeed Dc Transmission System Based On Partition Of Receiving System

The situation of economic development and energy reserves in our country are generally reverse distribution,so the wide range of power energy flow configuration has become the main development direction of China's electric energy.The state has put forward a nationwide network development strategy for the hydropower supply from the Southwest to the East and the support between the North and the South.Compared with AC and DC two transmission modes,DC transmission has its unique advantages in transportation distance,transmission capacity and operation control performance,so DC gets a rapid development.Therefore,research on the interaction mechanism of DC voltage and reasonably distribute the high density DC transmission line terminal regions in the receiving system which is of great significance to the safe and stable operation of the AC/DC hybrid power grid in the future.In this paper,the current development of the multi infeed DC system was briefly introduced and analysed,by summing up the existing research results,the DC interaction mechanism of multi-infeed system and the multi-infeed interaction factor and the quantitative index to characterize the voltage stability of DC transmission which is called multi-infeed short circuit ratio are focus analysed.Aming at the situation of more than one DC drop to the same receiving system at the same time,the paper established the equivalent model of multi-infeed DC system and gave equivalence analysis on the basis of multi port Thevenin theorem.Voltage stability is the key to stable operation of DC line,if DC line voltage overstep the stable range that will lead to commutation failure,DC blocking,and so on.The paper proposed the selection method of partition based on correlation index and the selection method of clustering according to the coupling index.According to two different partition methods,linear weighted method and variable weight evaluation method are used to evaluate the schemes.Finally,the placement of IEEE 14 node system is planned,and the effectiveness of the proposed method is verified by the comparison between the traditional method and the method proposed in this paper.