Research On Power System Protection Scheme Based On Substation Area Information

Wide-area backup protection system is applied in large power grid. By using the advanced communication and information technology, the system could collect more information and solve the shortcomings caused by traditional backup protection. For example, the delay of protection and affected a lot by the operation mode of grid. The system could control the power system and make the system more stable. The wide-area protection has many functions and needs to process information very fast. If the realization of all the functions and information processing relies on just wide-area decision-making center, it will bring lots of problems such as lack of hardware processing capacity, communication congestion, configuration too complex.etc.To solve the above problems, this paper presents the structure of wide-area protection in which the whole substation act as the basic unit. Wide-area protection is divided into two levels, substation protection and regional protection. The substation protection controls the substation and deal with faults happen in the substation. At the same time, it provides the relevant information to the master station. The regional protection deal with the faults occur on the transmission lines of the area which uses the information uploaded by the slave station. The regional protection could also be used as backups of slave stations. This structure is very simple and clear, the proposed structure has important theoretical significance and practical significance.On this basis, this paper gives the structure of substation protection system and the hardware design. The substation protection system uses the integrated structure, which integrates all the backup protection of the componenrs in the substation. The substation installs two backup protection units to improve the reliability. The communication scheme in the substation is also presented.Finally, the paper propose two algorithm. The fault location based on the differential principle uses the whole substation as the differential unit. This method could be used as the starting element of both backup protection and monitoring of master station. The fault location based on the direction matrix uses the direction information. The fault location can be determined by making the sequence judgment of whether the fault ocurs in the transformer, transmission lines, or buses. The simulation verification and analysis show that these two algorithm are of simpleness and good traits on fault tolerant and expansion.