A detailed model for a thyristor-based static transfer switch

Abstract

Industrial customers often suffer from supply voltage interruptions and sags due to the increase in the utilization of sensitive equipment in the process automation and control. An effective way to improve power quality and reliability of sensitive customers is to use a static transfer switch. This device enables a very fast change in the supply of the customer to an alternate feeder providing adequate power conditioning for several power quality problems, such as voltage sags, swells, and interruptions. In this paper, an analytical model of STS is proposed and its performance is verified using the electromagnetic transients for dc (EMTDC) simulation package. Simulations using this model are performed in order to handle voltage sags based on real measurements on an actual industrial customer's supply voltage. Different phase angles and magnitudes of the two alternate source prefault voltages and different fault instances are considered.

IHTS development for Uninterruptible Power Supply at UPS fault

“…[4] Also, it has an advantage that possible wrong may not exist in power supply of load even if a critical situation including control function fault of UPS's interior happens. [5] 2. UPS's problem in industrial a) Accident of the industrial field Actual condition analysis of STS operation in an industrial field.…”

Safe-triggering-region control scheme for suppressing cross current in static transfer switch

“…Several researchers addressed the problem of the cross current [11][12][13][14][15][16][17]. According to [14,15], a relationship exists between the magnitude of the cross current and the phase difference between the two feeders.…”

“…Operation of a sensitive load can be disturbed by the common voltage sags, swells and interruptions. Recent studies [7][8][9][10][11][12][13][14][15][16][17][18][19] identify solid-state transfer switch (STS) as a possible cost effective solution to power quality problems. STS, see Fig.…”

“…Some of the difficulties arise due to the limited resolution of current sensors, the smoothing response of the current filters, and rather long current decay time [11]. To tackle the problem, [12] introduced a safe gating strategy which initialized the transfer only when phase voltage and line current in both feeders are of the same sign. However, no evaluation of the worst case transfer time was given.…”

Determination of Locations for Static Transfer Switches in Distribution Systems Using Genetic Algorithms and Goal Programming

“…In the distribution system of the utility (rather than customer) side, there are several approaches to improve the voltage dip phenomena: Static Transfer Switch (STS) [1][2][3][4], Transient Voltage Restorer (TVR), and Static Tap Changer (STC) [5]. The STS enables a sensitive load to transfer its power consumption from one source to another during 0.25 cycles.…”