Experimental investigation of a variable speed constant frequency electric generating system from a utility perspective

SUMMARY As efforts are accelerated to improve , the overall capability and performance of wind-electric systems, increased attention on variable speed configurations has developed. A number of potentially viable configurations have emerged. Various attributes of variable speed systems need to be carefully tested to evaluate their performance from the utility point of view, i.e., a view of the machine from the generator terminals. With this purpose, the NASA experimental variable speed constant frequency (VSCF) system based upon a design by F. R. Schleif has been tested. The test configuration consists of a wound rotor induction generator and a line-commutated cycloconverter. In order to determine the usefulness of these systems in utility applications, tests are required to resolve issues fundamental to electric utility systems. legitimate questions exist regarding how variable speed generators will influence the performance of electric utility systems; therefore, from a utility perspective, tests have been performed on the VSCF system and an induction generator at an operating power level of 30kW on a system rated at 200kva and 0.8 power factor. Since the VSCF is an experimental type system, the results obtained here should be viewed from the perspective of research in progress. The results of the tests have been summarized in three categories: power quality, voltage/VAR management, and dynamic behavior. The character of the power generated by the system has two predominant modes of oscillation: one that varies from 2p to 4p, and another mode that is associated with the slip frequency. In addition to this low frequency