Reactive Power And Voltage Management Of The Power System Based On The Region Balance

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,making the system disintegrate.Therefore how to judge the system voltage stability weak nodes and weak area has become a focus problem.This paper aims to put forward a approach for reactive power and voltage management and provide information for the managers to make a decision.Reactive power can not be transmitted by the long distance,Voltage and reactive power is a local problem,thus the entire power system voltage stability is linked to the regional balance of reactive power.The idea of the reactive power stratification and district management requires us to divide the entire power system into small parts in accordance to some principle.The regional division is an effective means to coordinate the reactive power and voltage management.In this paper,we first conduct an in-depth study against the existing methods of regional division,then propose the method of the electrical distance that has the universal significance.In it,the definition of electrical distance and clustering analysis are the focus.Secondly,use the fuzzy clustering electric distance method to divide the big power system to several small parts.It deals with these questions such as isolated nodes,PV nodes and combination of sub-regions which belong to this kind of EDM.Finally from the perspective of the regional independence,give the suggestion to the reactive power and voltage management through the analysis of the reactive power margin.It uses the tangent vector method to identify the voltage weak nodes in every region,then analyze the reactive power margins of these nodes by the U-Q curves,giving the suggestion that the voltage monitoring should focus on the voltage weak nodes and the nodes that have the smallest reactive power margin.The simulink results of IEEE-39 and IEEE-118 test system verify the validity and accuracy of the method.