SYNCHRONOUS MACHINE PARAMETER EXTRACTION FROM REAL TIME OPERATING DATA

SYNCHRONOUS MACHINE PARAMETER EXTRACTION FROM REAL TIME OPERATING DATA

Abstract:

A method is proposed for extracting the parameters of a round rotor synchronous machine using real time operating data. The machine is modelled mathematically as a set of differential equations. These equations are linearized into algebraic equations from where the unknown parameters – stator resistance s r , stator leakage inductance ls L , direct axis magnetizing inductance md L , quadrature axis magnetizing inductance mq L and field winding resistance ‘ fd r – are extracted in the same way that a set of simultaneous equations is solved. Stator phase voltages and currents and field winding voltage and current provide the input measurements. The method yielded good result with white noise added to the signals up to a signal to noise ratio (SNR) of 20dB. Knowledge of the machine parameters is crucial for performance evaluation, optimal utilization of generator loading and for safer work of generator operating in parallel with the power system. The results obtained by the method were also compared with those obtained on the same machine at standstill – the stator phase resistance and synchronous reactance were measured as 1.652Ω and 52.22Ω respectively while the present method yielded values of 1.587Ω and 33.96Ω respectively. Furthermore, the method was used to extract the parameters of a 1kVA round rotor synchronous machine in the laboratory which yielded stator phase resistance of 10.5Ω, synchronous reactance of 44.2Ω and field resistance of 7.5Ω.

SYNCHRONOUS MACHINE PARAMETER EXTRACTION FROM REAL TIME OPERATING DATA