Stability Study On Power System Based On Electronic Power Transformer

In recent years, there have been some new features for Chinese power grid: large gridinterconnection has been formed, distributed generation has been promoted, smart gridconstruction is also on the agenda. These new features have a higher demand on powersystem stability and power supply flexibility. Traditional power transformer has beendifficult to accommodate these changes, so many scholars focus their reach onelectronic power transformer (EPT) which based on high power electronic technologies.EPT has strong controllability and high intelligent degree, so it will be widely used infuture power system. The research for power system stability changes due to EPTapplication has been an important field.To provide initial values for subsequent calculations, this dissertation firstly studiedthe power flow calculation method for EPT-based power system, an AC and DC alternatingalgorithm has been presented. The algorithm has been realized based on PSASP/UPI, thesimulation results showed the correctness of the algorithm and the effectiveness of the EPTpower flow control. Then established the EPTtransient stability calculation model andrealized the model base on PSASP/UD. The simulation results showed the transientstability for EPT is good. Finally, this dissertationanalyzed the small signal stability forEPT-based single machine infinite system. The impact of EPT for s ystem synchronizingtorque coefficient and damping torque coefficient is analyzed by torque analysis andcontroller parameters for EPT is designed by full-dimensional eigenvalue analysis. A time-domain simulation program based on Matlab has been proposed to prove these results, allshowed EPT can greatly improve the small signal stability of the power system.