Development of advanced solid-state transfer switch using novel hybrid switch devices

Abstract

Power quality issues of voltage sags and swells in the distribution system have been increasing these years. In many instances, the use of a solid-state transfer switch (SSTS) can be one of the most effective solutions. However, a conventional SSTS consisting of a pair of thyristor switches raises some significant issues in terms of large loss consumption and cooling. In order to solve these issues, the authors developed an advanced SSTS using novel hybrid switch devices consisting of high-speed mechanical switches and thyristor switches connected in parallel. In the proposed SSTS, the line current flows through the mechanical switch instead of the thyristor switch in the normal operation, resulting in negligible loss consumption and eliminating the need for cooling equipment. The most important key technologies for the SSTS are the high-speed mechanical switch with the opening time of 1 ms and the thyristor switch consisting of 12 kV rating thyristors. This paper presents the following aspects and operating characteristics of the proposed SSTS: (1) Construction and operating characteristics of the hybrid switch device. (2) Construction of the proposed SSTS using the hybrid switch devices. (3) Performance characteristics of the SSTS.