The Online Risk Assessment Of Power System Static Security Based On The Real-time Evaluation Model Of Transmission Line

Along with the increasing exposure of the limitations and shortages of the traditionalstatic security analysis methods applied in power system, people are now gradually turningthe key research to the uncertain analysis approaches. So far, the probabilistic load flowmethod which belongs to the uncertain analysis approaches has obtained a thoroughresearch. But the research of applying it to the risk assessment of power system staticsecurity is little from the point of view of ensuring the power system security. In allusion tothe defect existing in the traditional method of power system static security analysis, thispaper conducts the risk assessment of the power system static security from the angle ofrisk.This paper thoroughly discusses a real-time fault probability evaluation model oftransmission line considering meteorological factors. It divides transmission line into fiveparts of electric insulator, wire, lightning arrester, tower and ground wire and monitorsthem online and establishes the quantitative model of each monitoring parameterrespectively according to their specifications and actual operation situation. Then using thetheory of unascertained rational numbers combining with fuzzy assessment method, thispaper establishes a real-time and hierarchical fault probability assessment model oftransmission line based on the on-line monitoring data, meanwhile it considers the currentmeteorological conditions and then sets up a real-time evaluation model of transmissionline’s fault probability.This paper thoroughly discusses the probabilistic load flow which can be used in thestatic security risk assessment. By taking into account all kinds of uncertain factors existedin power system, this paper establishes the probabilistic model of the uncertain factors andthen applies the Cornish-Fisher expansion based on the semi-invariant to calculate the probabilistic load flow. At last this paper analyzes the uncertainty of the line power and thenode voltage caused by the uncertainty factors.This paper proposes a method of online risk assessment of the power system staticsecurity from the point of view of framework and establishes the online risk indexessuitable to the online risk assessment. In order to achieve the real-time requirement of theonline risk assessment, this paper proposes a screening index and uses it to conduct thereal-time contingency screening and ranking of the forecast fault set. On the basis of this, ituses the method proposed by this paper to calculate the comprehensive risk index of powersystem and it can truly and comprehensively reflect the risk level which the power systemis in under the current operation state.