Research On Leading Phase Operation Of Synchronous Generator Based On Least Square Method

With the construction and development of modern power grid with ultra-high voltage,large capacity and long-distance transmission,the problem of high voltage at the junction point in low valley operation of power system is becoming increasingly prominent,which seriously affects the safe operation of power transmission and transformation equipment.Among the commonly used voltage regulation methods,generator leading phase operation has been gradually applied because of its unique advantages such as smooth voltage regulation,no additional investment and easy implementation.Therefore,making full use of the voltage regulation potential of grid connected generators is of great significance to reduce equipment investment,solve the contradiction of regional reactive power surplus,formulate voltage control plan,ensure the power quality of power grid,and improve the stable operation level of power system.The leading phase test of generator is an important link to determine its leading phase capability.The results of leading phase test are the basis for parameter monitoring,reactive load regulation and site operation regulation.However,it is impossible to enumerate all the working conditions in the field test of generator leading phase,and the working conditions required by the power grid leading phase operation are certainly different from those in the test,so the reference of the test results is poor.Therefore,how to establish an appropriate model to reflect the leading phase capacity of the actual generator is worth studying.According to the basic theory of leading-phaseon,the limiting factors of leading-phase operation was analyzed,and the test scheme according to the requirements of national standard was designed,that is,taking a 600 MW hydro hydro-generatore research object,the leading-phase test is carried out,and the parameters such as reactive power and power angle of hydraulic turbine are obtained,which verifies the main limiting factors of leading-phase operation of synchronous generator and obtains the leading-phase operation limit value.In view of the phenomenon that the parameters of synchronous generator change nonlinearly under the leading phase operation condition of synchronous generator,it is difficult to accurately predict the leading phase operation ability of synchronous generator by using the conventional simulation method.In this paper,the least square method is used to identify the key parameters affecting the leading phase operation —— the quadrature axis reactance of synchronous generator,and the terminal voltage of synchronous generator is obtained;In order to solve the problem that the inductance and reactance parameters of transmission line can not be accurately calculated,aiming at the problem that the resistance and reactance parameters of transmission line can not get accurate values,the accurate parameters of transmission line are obtained by programming calculation.Based on the identification of synchronous generator quadrature axis reactance.on this basis,the mathematical models of synchronous generator,synchronous generator excitation system and prime Mover speed control system are established,and the simulation modules is constructed by using these three mathematical models to simulate the single machine infinite bus system with synchronous generator running ahead of time.The influence of external line parameters on synchronous generator’s leading phase operation is analyzed,and the simulation data is compared with the test data.Aiming at the deviation between the simulation data and the experimental data,the synchronous generator parameter identification is introduced to correct it,and the correction results are compared with the experimental data to verify the accuracy of the simulation model.The operation capability of synchronous generator is predicted and guided by theory,in this paper,the stability of power system can be improved,which has a certain engineering value.