Experience with SSFR Test for Synchronous Generator Model Identification Using Hook-Jeeves Optimization Method MAHDI POURGHOLI M.R. AGHAMOHAMMADI V.J. MAJD Power and Water University of Technology (PWUT) IRAN pourgholi@pwut.ac.ir Abstract: Accurate generator modeling allows for more precise calculation of power system control and stability limits. In this paper a procedure using a set of measured data from Standstill Frequency Response (SSFR) test on MontazerGhaem gas power plant’s synchronous generator is used to obtain synchronous machine. A novel approach is used to find d-axis which is different from standard SSFR scheme which can save the time in doing SSFR tests. Hook-Jeeves method is used for optimization purpose. The test procedure and identification results are reported. Keywords: SSFR, Synchronous generator, Parameter identification 1- Introduction Stability analysis is one of the most important tasks in power system operations and planning. Synchronous generators play a very important role in this way. A valid model for synchronous generators is essential for a reliable analysis of stability and dynamic performance. Almost three quarters of a century after the first publications in modeling synchronous generators, this subject is still a challenging and attractive research topic. Two axis equivalent circuits are commonly used to represent the behavior of synchronous machines. The direct determination of circuit parameters from design data is very difficult due to intricate geometry and nonlinear constituent parts of machines. So several tests have been developed which indirectly obtain the parameter values of equivalent circuits. The stand still Frequency Response (SSFR) test has been widely accepted for extraction synchronous machine parameters. The following advantages can credit to the SSFR method: 1) It is easy to implement at the factory or during outages for routine maintenance without risk to the machine, since the tests involve very little power. 2) The ready availability of powerful computer tools have eased the data logging and analysis procedures. 3) Unlike the ANSI-standardized short-circuit test, the SSFR approach can simultaneously provide the equivalent circuits for both direct and quadrate axes, and at the present time, seems the most appropriate for modeling the machine behavior for stability analysis. Frequency response testing of electrical machines as a means of determining their parameters was introduced by [2] but the main thrust for the current work stems from the comprehensive study of the problem initiated by EPRI which culminated in the workshop in 1981 [3]. In [4] presented results of frequency response tests carried out on a 555MVA machine, with limited frequency range of 0.01 to 10 Hz but this was sufficient to identify a third order model for the machine. In [5] presented results for third order models for several machines introducing the concept of unequal mutual in the direct axis. In [6] proposed a new third order model claiming it as an improvement on the limited second order model. In [7] offered a recursive least squares algorithm with a frequency dependent weighting function to accentuate particular frequency ranges as an aid to the identification of the time constants. Numerical curve-fitting methods were used in all of the above papers. In this paper an experience with SSFR test on MontazerGaem gas unit generator has been presented and used Hook and Jeeves optimization method for curve fitting purpose. 2- MACHINE MODELING The structure of the synchronous machine model used Proceedings of the 7th WSEAS International Conference on Simulation, Modelling and Optimization, Beijing, China, September 15-17, 2007 488