Analysis And Research Of Power System Cascading Failures Based On Complex System Theory

In order to meet the nationwide optimal configuration of energy resources, and under the guidance of the “west to east, north and south mutually supplies, building the national network” policy, China will build EHV AC/DC hybrid power grid with the EHV AC/DC grids as the backbone network and with the coordinated development of all levels power grids. However, the larger the power grid sizes and the more application of new energy and technology, the more complicated the system is. In order to avoid the worldwide blackouts, we must analyze and study the mechanism of cascading failures which can cause blackouts.Firstly, the complex system theory is analyzed in this paper. The composition of the theory and the applicability in the power system is analyzed first of all, and then the research based on the complex system theory was divided into several directions.After that, the core part of the theory, namely the self-organized criticality and the complex network theories were analyzed based on their different emphasis in the cascading failures research and the results of the power system are in line with the inherent characteristics of complex system. The simulation models based on these two theories are summarized and prospected their applications in power system cascading failure.Secondly, based on the entropy theory is suitable for the ordering of complex system, the entropy indicators were applied to the evaluation system of the operation state of power system in this paper. The existing entropy indicators were summarized and a new power flow entropy indicator weighted by regional average load rates which were corrected by average coefficient of variation. And the results of this new indicator can reflect the power flow distribution level more accurate.Finally, the cascading failure evolution of EHV AC/DC hybrid power grid was analyzed in this paper. At first, the reciprocal effect of AC and DC transmission systems in EHV AC/DC grids was analyzed in this paper; then the factors needed to be considered based on EHV technology were summarized; a cascading failures set establishment method based on power flow entropy was proposed and the simulation results by PSD-BPA program verifies the validity of the cascading failures set at last.