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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.

In this paper, the impact of high wind power and photovoltaics penetration on the dynamic behavior of an island power system like one operates in Crete is investigated. Several simulations were performed leading to the fact that it is possible to achieve higher level of renewable energy sources penetration without significant dynamic security problems, if power units spinning reserve exists and the corresponding control systems have a sufficiently fast response.

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This paper deals with the application of Thyristor Controlled Series Capacitors (TCSCs) suitably rated for radial distribution circuits. The various problems existing on long distribution lines that can be alleviated by the connection of variable series compensation, as a TCSC provides, are discussed. An important feature is the capability of the TCSC to operate as a short circuit current limiter. Thus, sensitive loads connected to nearby substations will not experience any voltage sags caused by faults on the distribution line where the TCSC is connected. The benefits of the connection of a TCSC on a radial distribution system are verified by means of the ElectroMagnetic Transients for DC (EMTDC) simulation package.