Examination of Loss of Excitation and Assurance for Pumped Capacity Machines during Starting With Reversible Synchronous Machines

Abstract

The reversible synchronous machines in a pumped station are put into operation frequently for effective operation of the hydro pumped-storage system. The detection of loss-of-excitation (LOE), which is a common failure for synchronous machines, must be guaranteed not only in normal operation, but also under starting and other possible operation conditions. A model of pumped-storage units under the starting condition was developed using the SimPower Systems in Matlab/Simulink. The simulation results and real tests of a pumped-storage power plant in northeast China were presented. The LOE characteristics during starting were analyzed for the first time. Since the frequency of voltage and current runs up gradually from zero to the rated frequency during starting, conventional LOE protections based on impedance under the rated frequency have to be disabled during starting. For this reason, a novel LOE protection was developed based on the R-L time- domain model and the least-square algorithm. Theoretical analysis and simulation tests demonstrate that the proposed LOE protection method is correct and valid.