| Due to the large adjust inertia of the diesel generator sets, the quality of powersupply would decline when a large load disturbance occurs to the diesel generatorsets, and the poor quality of power supply would limit the application of the dieselgenerator sets. This paper aims to improve the stability of the voltage amplitude andfrequency that the diesel generator sets output at impact load condition. Tocompensate the poor adjust ability of the diesel generator sets, deeply researchwould be done on the math model of diesel generator set and technology of powercompensation.Firstly, a mathematical model of diesel generators is built, the dynamicperformances of diesel generator sets under a variety of load conditions is analyzedbased on the model. A Matlab simulation model of diesel generator sets is built toverify the previous conclusions, and to provide conditions for subsequentcompensation system performance simulation tests.Secondly, to suppress the voltage amplitude and frequency fluctuations that thediesel generator sets output under impact loads condition, a parallel powercompensation system connected to the ac bus is used to release or absorb the powerdifference between generator sets and loads. A three-phase VSI (Voltage SourceInverter) is selected as the main topology of the compensator. And then establish themathematical model of the compensator. The relationship between the instantaneouspower and the current of the compensator is derived by analyzing the dq model of it.To compensate for the regulation lag of the diesel generator active power, proposethe compensation strategy based on speed closed loop. To further improve thedynamic response of the compensation system, proposed the control strategycomposited with speed closed loop and the load current feedforward. To detect theactive current, reactive current and harmonic current of the load, the i p-iq methodis used.Thirdly, study the energy storage system based on the ultracapacitor, design theenergy management system using the triple bi-directional DC-DC converter.Combined with the working state of the parallel compensation system, propose theultracapacitor’s energy manage strategy under load disturbance condition using thedc bus voltage closed loop control, and the initiative charging strategy based on theultracapacitor’s voltage under steady-state is also proposed.Finaly, the parallel power compensation system and build its simulation modelin Matlab to simulate those control strategy proposed above. Based on the experiment platform, completed the control algorithm software design. Verify theeffectiveness of the parallel power compensation system in improving the quality ofpower feed by diesel generator sets by experiment. |
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