Zero-Cross Triggering Technology of Series SCRs with Optical Fiber at Medium Voltage: Application for Thyristor Switched Capacitor

With the development of power electronics technology, more and more power electronic facilities have been used in power system. The valve stack of series SCRs is the key to realize the dynamic VAr compensation with thyristor-switched-capacitor at medium voltage distribution network. This paper presents a firing technology as a solution for MV TSC. TSC with "transient-free" switching process is analyzed and zero-cross gating technology is required. Optical fiber and series zero-cross optoisolators triac drivers are adopted as parts of triggering system to solve the problems of isolating, zero-cross detection, gating energy, etc.. The performance of this triggering system was tested by field experiments, which showed satisfied effectiveness and certified its validity to be used as the executive component of TSC