Parameter estimation of synchronous machines

In this work, we examine the influence of field voltage variation during a sudden short-circuit test and its direct impact on the parameter identification of synchronous machines. The test standards establish that field voltage must be kept constant during the short-circuit test. However, due to the presence of impedances in the voltage supply, control of the excitation system along with many other factors, field voltage may vary during this test. This work proposes a method to recover the machine parameters even when high amplitude field voltage variations are presented during the sudden short-circuit test. In addition, an algorithm capable of defining maximum field voltage variations along with its correspondent duration in order to respect a certain parameter estimation error is proposed. Finally, the models developed in this paper are investigated using data from a 140 MVA synchronous machine.

In the figures below CFVI refers to constant field voltage variation and VFVI refers to variable field voltage variation. The CFVI is the method traditionally used in the parameter estimation of synchronous machines, and the VFVI is the method proposed in this work, which is capable of properly recovering the machine parameters even in the presence of field voltage variations during short circuit test.

Related Publications: 

1. VAD Faria, JV Bernardes Jr, EC Bortoni. Parameter estimation of synchronous machines considering field voltage variation during the sudden short-circuit test. International Journal of Electrical Power & Energy Systems, 2020.