Analysis And Visualization For The Voltage Stability Weak Area In Power System

Since 1970's, system disintegration accidents caused by voltage instability have occurred many times in some big electric power systems overseas, which have caused long time large area power cut and huge economic loss. The system voltage collapses are often caused by voltage instability of some bus or some area, then proliferate to the overall system, make the system disintegrate. Therefore how to judge the system voltage stability weak nodes and weak area has become a focus problem.This thesis aims to propose some practical voltage stability indices, and carry on thorough analysis to the voltage stability weak area. First through comparison of voltage stability tangent vector index, the power loss sensitivity index as well as the singular value index, then makes the system operators fixes their voltage stability monitoring and prevention stress on the weak nodes and weak area.Next regarding estimating system load margin, although the minimum singular value of the power flow Jacobin takes on linearly compared to the load increasing in general, it is influenced by the change of PV nodes. When generators and reactive power generator reach their reactive limits, the corresponding rank of the power flow Jacobin will augment simultaneously, and cause the minimum singular value change suddenly, then lose the commensurability to the value before node type change, this affects its linear nature. This thesis use the P/C technique to eliminate the sudden change of the index, improved its linearity.Moreover, for a system congaing thousands of nodes, it is extremely difficult to estimate the system state quickly. With the developing of the computer technique, visualization technology obtains more and more attention. This thesis use the intuitive of graph, achieve the visualization of the voltage stability weak area by Surfer.Finally the thesis uses IEEE-14, IEEE-118 test system to verify the validity and accuracy of the improved method, and provides a usable tool for the study of voltage stability.