Study On The Protection Principle For Wind Farm Collector System

In recent years, with the integration of large-scale wind power into power grid, wind farm protection characteristic is of great importance to the security of the wind farm and the power grid. The electric energy of the wind turbine is sent to the grid by collector bus and line. If the bus and the line protections behave incorrectly, it will seriously affect the safe operation of the power grid and the reliable power supply. Therefore, it has important theoretical significance and practical application value to analyze the adaptability of the protection of the wind farm collection bus and line, and to study the novel protection.In this thesis, the main research contents are the adaptability and novel principle of the protection of the wind farm collection bus and line.First of all, adaptability of the protection of collector bus is analyzed. When phase-to-phase fault occurs, differential protection based on the differential principle is still applicable to the bus. When single-phase grounding fault occurs, conclusion that bus differential protection is no longer applicable is drawn through two aspects of theoretical analysis. Single-phase grounding fault cannot be removed immediately. Then novel algorithm based on the amplitude comparison principle of the zero sequence current is put forward. The validity of the proposed algorithm is verified by DIGSILENT simulation.Then, adaptability of the protection of collection line is analyzed. Taking a practical wind farm in Jilin as an example, combined with the configuration scheme and the setting value of each protection, the conclusions that current backup protection cannot meet the selectivity and the zero sequence current protection cannot meet the speed are drawn. Thus, a new phase fault protection algorithm based on fault component current amplitude comparison principle is proposed. The new algorithm based on zero sequence current comparison principle is proposed for the single phase fault of a collector line. The validity of the proposed algorithm is verified by DIGSILENT simulation.Finally, in order to solve the existing problems, based on the proposed collection bus and line protection algorithm, a set of 35kV substation-area protection scheme using local multi information is proposed, which can protect all faults of the collector bus with line. It can also act as the backup protection of box-type transformers. The scheme is divided into three parts, the fault startup judgment, the fault location and the tripping strategy. The validity and superiority of the proposed scheme are verified by four DIGSILENT simulation examples.