POWER MANAGEMENT IN MOBILE ELECTRICAL POWER SOURCES WITH SUPERCAPS AS ENERGY BUFFER Jan LEUCHTER 1 , Pavol BAUER 2 , Vladimír ŘEŘUCHA 3 , Vítězslav STEKLÝ 4 1,3,4) University of Defence; Kounicova 65, 612 00 Brno, Czech Republic; Jan.Leuchter@unob.cz; Vladimir.Rerucha@unob.cz; Vitezslav.Stekly@unob.cz; 2) Delft University of Technology Mekelweg 4, 2628 CD Delft, the Netherlands P.Bauer@ewi.tudelft.nl Abstract. The paper brings some practical results of research devoted to the new generation of mobile electrical power sources (EGS-Engine Generator Sets), based on the VSCF technology (Variable Speed – Constant Frequency). In this EGS the driving motor is optimally controlled in accordance with the load power thus decreasing the fuel consumption. The output voltage and frequency of generator are stabilized by means of power electronics. This paper brings some new analysis and results of the problems with power and voltage drops at sudden increase of the load. The analysis of dynamic behaviour proved, that the disadvatnageous dynamical properties of new concept EGS with VSCF technology could be improved by supercapacitor based energy storage element. 1. Introduction The mobile electrical power generating sets (EGS) are usually based on the synchronous generator driven by combustion engine. The engine speed is stabilized on the value, corresponding to the required output voltage frequency. The output voltage is usually controlled by means of the generator or its exciters magnetic field exciting current. Such concept of EGS operates with constant engine speed. That can be disadvantageous because the output power of engine P [W] and fuel consumption s [g·kWh -1 ] is speed-dependent, as it is shown in Fig. 1. EGS with constant speed concept operates with low efficiency and high fuel consumption on the low loads of EGS. The 3 rd EGS generation (EGS3G) is based on some new technologies [1]. The fundamental difference consists in the optimally changed engine and generator speed in contrary to a constant speed. The optimality criterion secures the minimum fuel consumption in correlation with the instantaneous EGS load. The historical change from constant speed in EGS to optimally variable speed in EGS3G is based on the analysis of the EGS loading regimes. Due to the low average the EGS load the engine operates often at the superfluous high constant speed (3000 RPM) in uneconomical and from the point of view of the environment undesirable condition. The simplified block diagram of EGS3G can be seen in Fig. 2. Fig. 1. The fuel consumption and speed as a function of output power of diesel engine Instead of field excited synchronous machines, the synchronous generators with permanent magnets (SGPM) proved to be the most suitable source of electrical energy in the new concept of EGS. The constant frequency and required output voltage value at variable speed and load is then achieved not by means of the engine speed stabilization and the change of generator exciting current, but by means of power electronics voltage and frequency converters. The EGS3G can be considered as comparatively sophisticated mechatronic system, consisting of mechanical part, electromechanical energy conversion part, power electronics output power, voltage and frequency transformation and stabilization part including the optimum speed control part based on the microprocessor program. 1500 1800 2000 2300 2600 3000 3600 252 247 245 250 258 270 300 0 500 1000 1500 2000 2500 3000 3500 4000 3 4 5 6 7 8 P [kW] n [rpm] 0 50 100 150 200 250 300 350 s [g/kWh]