Complex Power Grid Dimensionality Reduction And Operation Monitoring Based On Transmission Paths

With the increasing interconnection of the power grid and large-scale renewable energy integrated to the grid,power transmission paths of complex power grid from the supply side to the demand side exhibit great uncertainty especially as operation modes change.In this situation,it is difficult to determine the power flow distribution and vulnerable lines with the regular operation experience.Therefore,studies on evaluating power flow trends in the power grid,reducing the dimension of the grid and implementing effective operation monitoring are of great importance.Based on the real time power flow,this thesis analyzes the power flow trend of the complex power grid and a method to fast identify transmission paths is proposed to realize the complex power grid dimensionality reduction.The characteristics of electrical distance and bus phase angle are adopted to determine the constitution of transmission sections.Combined with operation indexes such as the cutset angle in monitoring the power grid,the critical transmission sections are established.Main work of this thesis is as follows:(1)The power grid is converted to a weighted direct graph based on the real time power flow,and the sources and sinks of the graph are divided into several nodes.Then the network is described as a finite number of independently connected subgraphs which are defined as transmission paths in order to describe the power transmission between the sending end and the receiving end.The depth-first walk method is introduced to identify all the transmission paths of the network.With such steps,the power grid is decoupled to several transmission paths and the dimension of the power grid reduces effectively.(2)The transmission paths of the complex power grid are chosen as the basic research unit.A method of determining the transmission sections based on the electrical distance and bus phase angle is proposed.On the basis of the bus phase angle parameters of transmission paths,the transmission sections reflecting the bus phase angle clustering are first determined by K-means clustering algorithm.Then combined with the electrical distance between transmission section buses,the transmission sections reflecting the electrical characteristics and the phase-angle characteristics are determined.(3)The operation monitoring method based on transmission paths is proposed.The transmission section buses are as the boundary buses of monitoring analysis.The operating indexes such as the cutset angle are put forward to reveal the critical transmission sections.(4)Researches in this thesis have been applied to a real bulk power system in Southern China,feasibility and effectiveness have been validated.