Research On Impact Of Excitation System Adjustment Coefficient On System Damping Characteristics

In recent years,the process of power system interconnection in the whole country is speeding up,which makes the power system run more and more to the critical point and tend to limit operation.Under the condition of heavy load of the system,the generator can produce weak damping or even negative damping when the system is excited by high speed and high magnification excitation system.Due to the lack of damping in the power system,the phenomenon of low frequency oscillation has occurred,a serious threat to the stability and safety of the power grid.The adjustment coefficient of generator excitation system is an important parameter to describe the external characteristics of synchronous generator.Because the control link difference coefficient function of excitation system,so the rational difference coefficient setting not only for the reactive power distribution system between the units have a certain influence,but also affect the damping characteristic of the system,the reasonable parameter tuning of the safe and stable operation of the system is conducive to.The excitation system of generator between the difference coefficient of tuning effect on the damping of the system,firstly the Heffron-Phillips model of single machine infinite bus system is extended,established the two machine extended Heffron-Phillips model parameter analysis of coupling relationship between two generators.The model is suitable for the analysis of the mutual influence between the two systems.Based on the transformation of physical properties,the two machine extended Heffron-Phillips model is established to calculate the differential coefficient of excitation system.Based on the model,study the difference coefficient of influence on the damping of the system by the method of characteristic value,correlation between the proposed adjustment sensitivity index to reflect the system damping and excitation system of difference coefficient of the size of the.Key system parameter analysis of effect of damping and difference coefficient of correlation,the results of the study show that the transmission line system of electric distance,the generator inertia time constant,generator output power and load center are the excitation system difference coefficient and system damping between important factors for the excitation system of multi machine system adjustment differential coefficient setting configuration has certain guiding significance.