Absfract-This paper is focused on the performance of a novel type of adjustable speed power generating set.The set consists of a diesel engine, an axial type permanent magnet generator and ACIAC converter. The engine is designed to operate over a wide speed range powering a high efficiency permanent magnet generator. The generator output is fed to a power electronics controller designed to maintain the voltage and frequency to the requirement of the load. The power to weight ratio of the set is considerably more than conventional set incorporating a wound field generator and RIC engine running a t 1500/1800 rpm. The axial flux generator used is light, short and higher in eficiency than conventional type. The unique feature of the system is the control algorithm, which ensures fast system response and accurately map the engine torque curve to load demand. The paper will present the concept and main features of the recently developed Variable Speed-Integrated Generating set.

PurposeThe purpose of this paper is to provide a new theory of adjustable speed decoupled generation which has the potential to challenge existing coupled generation based on a classical synchronous generator operating with fixed speed.Design/methodology/approachThe paper's approach is a theoretical consideration of the drawbacks of conventional fixed speed generation based on a synchronous generator and proposal of problem solutions by the introduction of a decoupled generation system with additional degree of freedom. Computer calculations are used as design and for preliminary verification. Tests in a real laboratory system equipped with modern components such as electrical machines and power electronic converters proved the theory.FindingsDecoupled generation is realized in a very original way using new blocks, integration method and control. The developed system has been awarded more than six world patents. The system has additional degrees of freedom in speed and grid connection operation.Originality/valueThe research team has concentrated its research over many years and developed a generation system which has been awarded a great number of patents. A special axial flux, light and simple permanent magnet generator was developed and integrated to the prime mover. A three‐phase AC/AC power electronic converter and a DSP controller are integrated to a very small size and low weight. The invented topology provides a very reliable operation, high‐quality AC voltage in fully three‐phase non‐symmetrical load. There were also presentations on world conferences (EPE, PESC, EPE‐PEMC).

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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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