Abstract：When the multi-power supply system is switched between each other, the performance of the uninterruptible power supply (UPS) circuit will be greatly affected due to the different grounding methods of the neutral line. The article analyzes and compares the impact of the three-level and four-level automatic transfer switches (ATS), and the different grounding methods of the neutral line on the UPS circuit when the multi-power system is switched. And according to whether the multiple input power supplies, input power and output power are independent of each other in the multi-power system, the concept of independent power supply system is proposed. Combined with independent power supply system, the effect of improving power quality is obvious, and the method is economical. There are two solutions to install output isolation transformer or bypass isolation transformer in the UPS circuit of multi-power system switching. Through the comparison and analysis of the performance of different UPS circuits, the optimal engineering application scheme is obtained, which is that the neutral line “breaks before make” four-stage ATS, and the UPS circuit with bypass isolation transformer. The circuit has the advantages of high reliability, no stray current, independent and electrical isolation between input power supplies and between input and output power supplies, and continuous neutral ground reference, which can effectively suppress common mode noise and reduce zero-ground voltage.
廉永乐, 王明, 李帅. 中性线不同接地方式在多电源系统切换时对不间断电源性能的影响分析[J]. 电气技术, 2025, 26(10): 8-15.
LIAN Yongle, WANG Ming, LI Shuai. Analysis of the influence of different grounding modes of neutral line on uninterruptible power supply performance in multi-power system switching. Electrical Engineering, 2025, 26(10): 8-15.
2025, Vol. 26 
