Research On The Influence Of OLTC Dynamic Regulation On Voltage Stability

With the rapid development of society and economy,power system,as the basic industry of industrial system and people's livelihood,is growing in size.With the increasing demand of people,maintaining the security and stability of grid voltage has become an important issue in power system.There are many factors causing voltage instability,the most common is monotonic instability,and monotonic instability is mainly solved by static voltage stability analysis method.Therefore,to study the problem of voltage instability,we need to focus on the study of power system static voltage stability analysis method.In this thesis,focusing on the stability of power system operation,the function of on-load voltage-regulating transformer in voltage stability system is explored,the instability of voltage system is discussed in detail,two kinds of common on-load voltage-regulating transformers and their voltage-regulating effects are listed,and the causes of their defects in operation are analyzed.In this thesis,Thevenin equivalent method is introduced to study the feasible method of voltage stabilization,and the expressions of static equivalent impedance,dynamic characteristic equivalent parameters and Thevenin equivalent impedance of Thevenin OLTC are analyzed emphatically.The dynamic equivalent impedance of Thevenin is obtained by calculating the increment of the quantity and the load current.For nonlinear systems,the maximum power can be achieved at the load point only if the static equivalent impedance mode and the dynamic equivalent impedance mode are kept the same.The dynamic equivalent impedance of the system is calculated by using the OLTC type calculation method.Thevenin proposed the following assumptions for the equivalent analysis method: when analyzing the intrinsic relationship between voltage stability and OLTC dynamic regulation,the system impedance mode margin should be selected as the basic parameter,and the system impedance mode margin should be changed in the experiment,and the phenomenon of negative voltage regulation should be recorded during operation.In order to test the experimental results,the IEEE30 and IEEE14 bus systems are synthetically applied.Through comparative analysis,it is proved that OLTC dynamic analysis can be carried out with the index of impedance mode margin,and the real situation and operation law of the system can be found out.