对线性对称组合控制器的可靠性进行了分析，指出：对称组合控制器可以改善并联系统中控制器的可靠。
Reliability of linear symmetric combination controller is analysed in this paper, pointing out the controller may improve reliability of controller in parallel system.
介绍了并联系统ups的特性及其实现，现场外接旁路的设计与具体操作，以及日常维护中的问题。
The characters and reality of double parallel system UPS, external bypass design and operation, and the Suggestions about the ordinary maintenance are introduced also.
本文以高频ups的并联系统为研究对象，研究分析了高频ups并联系统中的环流特性、并联控制、切换保护和系统监控等内容。
This paper focuses on the parallel system of High-frequency UPS, including analyzing of the circulating current characteristics, parallel control, bypass switching strategy, protection and monitor.
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