Study On High Power Power Quality Generator

Electrical equipments have requirement on power supply for good power quality. Some equipments, particularly the precision equipments such as computer, server, assembly line will perform abnormally and even be damaged when suffer power quality problem. In order to reduce the great loss caused by power quality problem, the sensitivity of electrical equipment on power quality should be tested and improved on stage of manufacturing. So, study the power quality generator, which can produce voltage sag, swell, flicker, harmonic and notch, etc, has great significance in practice.However, the power quality generators or equipments in the market currently are far from perfect. It have many disadvantages such as heavy, unable to move, intricate structure, etc. With the development of modern power electronics technology, computer technology and control technology, to develop new power electronics based power quality generator is available. The new power quality generator can generate all kinds of power quality signals and will be applied widely in university, industry and laboratory.This paper circumfuses the realization of prototype machine, using simulation and experiment method to discuss the theoretical and practical problems which need to be solved. The prototype machine adopts AC-DC-AC converter as main circuit. On the basis of main circuit, control strategies on rectifier and inverter were studied. The current hysterisis control strategy was applied in rectifier side to meet the requirements of rapid response, good precision and high power factor. Sinusoidal pulse width modulation (SPWM) and voltage hysterisis control strategies were studied for inverter side control and the differences between them were also discussed. For the purpose of getting better performance, the DC voltage and power circulating path of AC-DC circuit or AC-DC-AC circuit were studied. On the basis of instantaneous power equilibrium theory, DC voltage models were deduced. The models can be used in improving control strategies and circuit design. By analyzing the power circulating path between AC and DC sides, this paper studied the strategy to restrain DC voltage fluctuation. According to the study purpose and requirements, DSP was selected as control chip and Intelligent power model (IPM) selected as power device. After the software, filters, DC capacitor, control circuit and power circuit designed, a single phase prototype machine was realized. The prototype machine can generate power quality signals, such as voltage harmonics, sag, swell, flicker, notch. The results of experiment and simulation validated the control strategies, circuit design and analysis conclusion. Finally, the concept of power quality sensitivity testing system was brought forward. The system consists of power quality generator, electrical equipment and feedback channels. Power quality generator output signals to test the electrical equipment and capture its work state information by feedback channels. As an example, the prototype machine and an AC contactor composed a testing system. In this testing system, the AC contactor tested by a series of voltage sag and its performance data was collected. As experiment result, the ITI curve of the contactor was depicted. With the improvement in performance, the power quality sensitivity testing system will has broad application in future.