Smart and decoupled power electronic generation system

Abstract

The paper presents adjustable speed generation system with a newly designed and built axial flux shaftless and bearingless permanent magnet generator, and power electronic converter acting as universal ac power source. Speed of the prime mover is adjusted to meet load demand by real time load measurement and calculation. Thus the power electronics converter decouples the generator and load and then rotation of the generator is not related to electrical power system stability. Then such a system has another degree of freedom related to speed. The system is controlled by a Share DSP processor and provides high quality of the output power. Results of tests of 40 kVA power system driven by a Diesel engine are related to steady state operation and to transients. The system can operate with 100% of asymmetrical phase load with any changes o f output voltage. Oscillogram of step load operation confirms ability to accept 45% sadden change of load without any voltage distortion. 1. MTR DUCTI NDemand for electricity in both developed and developing countries is continuously increasing. The electric power is still produced by sources based on 19th century concept of a wound synchronous generator with controllable excitation system. Progress in power electronics resulted in adjustable speed drives, improvement of power quality by application of UPS and active filters. Now, there is a feasibility to change historical systems of power generation. Work presented in reference [l] discusses the recently developed generation system including variable speed. In the [2] simple single phase SkVA system with Diesel engine, permanent magnet generator and power electronic converter with double conversion is described. The double conversion means that a variable frequency voltage is rectified and then a dc/ac converter produces ac output voltage. Such a system can operate over a very narrow speed range. Low voltage system, with single phase (120V/60Hz) or three phase 120/208V. with also double conversion, is developed by [SI. The three-phase system operates with limited asymmetry of load. Hybrid, single phase, system with triple conversion, which combines variable speed generation system with battery storage was developed by [4] and [5]. In the [4] and [5] the speed is adjusted by dc voltage controller. Three phase system with stiff neutral, triple conversion and wide range of speed is developed by [6], [7]. The paper presents adjustable speed generation system with a newly designed axial flux shaftless and bearingless permanent magnet generator, and power electronic converter acting as an universal ac power source. Speed of the prime mover is adjusted to meet load demand by real time load measurement and ca1r:ulation. FI EO !;PEE0 VERSUS AD USTA LE SPEED GENERATI NThe fixed speed synchronous generator provides for two primary functions. First, the conversion of mechanical power to electrical one. Second, the assuring quality of sinusoidal fixed frequency voltage. At the beginning of the 20th century the integration of the two functions...

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