Alexander Schwery

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The present paper investigates the complete regulation strategy for a large double-fed asynchronous motor-generator equipped with a 3-level VSI cascade for applications mainly in the field of pumped storage plant. For the present application, the specific problem of the DC link capacitors voltage balancing is investigated. Also a sensorless method for the(More)
The drive system of a variable speed pump-storage power station consisting of a doubly-fed induction machine with a 3-level voltage source inverter feeding the rotor is presented. The advantages of variable speed pump-storage power stations are outlined. After a short comparison with the classical cyclo-converter solution the voltage source inverter(More)
This article presents the modeling, simulation, and practical application of a double-fed asynchronous motor-generator for pumped-storage plants equipped with a three-level VSI cascade. The problem of DC unbalance control is studied in this particular application. A solution is proposed and tested in practice. This solution uses a specific adaptable filter(More)
This paper presents the start-up and synchronization procedures of large variable-speed pump-turbine units in pumping mode. These procedures applied to a doubly-fed induction motor-generator with three-level voltage source inverters VSI cascade in the rotor side, can be achieved without any supplementary equipment, for instance without an autotransformer(More)
Stability is a primordial concern of power systems. From the generator point of view, it means that the machine must be able to attain an equilibrium state (possibly the pre-fault state) once the system is back to normal operation. For Synchronous Generators, the Equal Area Criterion (EAC) can be used to determine the maximum fault clearing time also known(More)
The reliability of the loss calculation is a very important issue during the electrical design phase of large synchronous generators. The paper presents a fully 3D finite element approach for the computation of eddy current losses in the stator clamping parts of a 450 MVA hydro generator. To take into account for saliency and saturation effects, the(More)