Research On Transient Power Quality Detection And Sliding Mode Control Method In Microgird

The microgrid technology is a research hot spot in electrical engineering field. There are two main reasons. One is that microgird is mainly with new energy power generations, so the environmental pollution is reduced obviously, which is in accord with the idea of energy utilization in harmony with environment protection in present-day society. The other is that microgrid can provide variety of power products, which can meet personalized demand of users. However, the inherent characteristics of distributed generation (DG), the special network topology and the operation characteristics of the microgrid bring unfavorable factors influencing the power quality of microgrid. Based on extensive reading correlation domestic and foreign literature, this thesis’Power Quality in Microgird’is carried on profoundly. The main contributions are as follows:1. A detailed description is given of the basic structure of micrigrid and power quality in microgrid. The concept and basic structure of microgrid is introduced, and microgrid characteristics are summarized. A detailed discussion is given of power quality problem in microgrid.2. Power quality in microgrid is analyzed, including voltage fluctuation, harmonic, etc. Profound research on voltage fluctuation and flicker is carried on, and it is stated systemically that power fluctuation of power generation is the reason of voltage fluctuation. By analyzing the radical reasons of power fluctuation of wind power generation and PV power, the main influencing factors have been found out.3. A new location method of transient power quality disturbances in microgrid on basis of mathematical morphological and backward difference is proposed. Profound research on morphological filter is carried on, including choosing the morphological filter structure element from shape, width, and height. Morphological opening operation and closing operation are used to be integrated to improve filtering accuracy. The simulation results show that the proposed method is accurate for detection, good ability in real-time, and simple in calculation.4. Profound research on control method of shunt active power filter based on sliding mode control is carried on. Based on the time-domain analysis of single-phase circuit of shunt active power filter, the sliding-mode control strategy is deduced. The simulation results show its validity and feasibility.The achievements of this paper establish theoretical basis and create practical value for research on microgrid technology, and the construction and operation of microgrid demonstration project.