This paper presents applications of the Exponential Static Load model used to represent voltage depending loads. This model has been used to represent loads of different types: Industrial, Residential and of Petroleum Extraction Fields.These loads belong to "Sistema Interconectado Patagónico" (SIP), a small power system of 1200 MW of peak load situated in the South of Argentina. Models of several load types have been validated by tests.Tests were made by applying steps to the feeding load voltage. Load voltage sensitivity coefficients were obtained for the different load types tested.Load models validated by tests were used for SIP modal analyses.Index Terms--Load -Load Model -Power system dynamic stability -Simulation -Testing.

Futaleufú hydropower plant has 4 Francis turbines rated 118 MW and it is connected to the power system by 2x330 kV lines. Studies carried out in the past did not predict the instable operation of Futaleufú after a 330 kV line fault, when some Futaleufú turbines are automatically disconnected as a consequence of the faulted line tripping. Load rejection caused by disconnected turbines generate large transients in the remaining turbines due to hydraulic coupling through the common conduits. Then, to improve related models and, therefore, to improve studies results of such a line fault it was necessary to make several tests in Futaleufú power plant. Finally, these models were used to conduct studies to design a new automatism, like the gate partial closing of the remaining turbines, to obtain a dynamically stable operation of Futaleufú after the disconnection by fault of a line of 330 kilovolts.

The "Sistema El&hico Patag6nico Intmectado (SFPI)" is an elechic system that involves the Argentina south region. This electric system is isolated fiom the other one in the north of the country. The 60% of its load is consumed by an aluminum production plant consisting of two 160 MW series of 200 electrolytic cells each one. Dynamic and transient stability studies carried out over this system, taking into Bccount present and future situations, with load and genedon grown at the aluminum plant and in the remaining system, require adequate modeling of this particular load. Tests and simulations canied out to obtain the electrolytic process load model are &scribed. Statistical behavior of the aluminum plant load variations is a n a l p 4 to estimate the spinning reserve in the system. By the way, available load shedding mechanisms at the aluminum plant, as a system control element, were tested and the results are analyzed.

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