Research On On-line Adjustment Of Arc Suppression Coil Resonant Grounding System Based On Special UPS

With the development of urban modernization,the grid system as the foundation of the city,the complex distribution environment,the traditional neutral point through the arc suppression coil grounding system,can not meet the compensation requirements for the ground fault capacitor current.For this reason,the following research is carried out on the neutral point of the grid through the arc-suppression coil resonant grounding system as the research object.Firstly,based on analysis of neutral point arc suppression coil grounding system,the problem,nonlinear inductance,the poor precision and bigger fault compensation current harmonic is presented.Aiming at these problems,an on-line adjustment of the arc suppression coil resonant grounding system based on uninterrupted power supply(UPS)is designed after consulting large number of references.And character of online,continuous and precise adjustment of the arc suppression coil is realized by UPS.Secondly,for paving the way for the operation of the arc suppression coil resonant grounding system,the wavelet transform is used to extract and analyze the transient component information to improve the line selection success rate after the analysis of the fault line.And resonant state is judged by detecting the negative sequence current of the faulty line power supply.Then,arc suppression coil tuning based on the special UPS transformer is designed by combining the advantage of the UPS in the current control and the wide adjustment transformer arc suppression coil with wider adjustment range and less harmonics.Inverter is the core of UPS.And the quality of the output power of inverter is related to the perfection of its control algorithm.The basic principle of SPWM modulation is discussed in the thesis.And PI control algorithm of traditional UPS inverter is optimized.The shortcomings of poor dynamic performance and low control flexibility in traditional PI control is solved by applying BP neural network algorithm,repetitive control strategy and PI control to the control of the inverter.And the control performance of the UPS is enhanced.Finally,the hardware and software of the transformer-type arc suppression coil system based on special UPS are designed.And the experimental platform is built to test the performance of the arc-extinguishing equipment.The current quality of the arc-suppression coil device is obtained by analyzing the experimental data.The high,wide adjustment range and low harmonic content verify the feasibility of this design.