Solid-state transformer (SST); Medium frequency transformer; AC/AC converter; Matrix converter Abstract This paper presents a novel topology of solid-state transformer (SST). In the design process, the AC/DC, DC/AC and AC/AC converters have been integrated to achieve higher efficiency. To obtain higher efficiency from other SST with DC-link topologies, the AC/DC and DC/AC converters have been i...

In the power system voltage sag become the important issue for industries. According to the survey 92% of the interruptions at industrial installations are voltage sag related. In various companies voltage sag may affect many manufactures and introduce sufficient losses in the power system. The voltage sag compensator, based on a transformer coupled series connected voltage source inverter, is ...

This paper presents the development of a wavelet based algorithm, for distinguishing between magnetizing inrush currents and power system fault currents, which is quite adequate, reliable, fast and computationally efficient tool. The proposed technique consists of a preprocessing unit based on discrete wavelet transform (DWT) in combination with an artificial neural network (ANN) for detecting ...

Power systems should have acceptable reliability in order to operate properly. Highly available and dependable protective relays help to obtain the desirable reliability. The relays should be periodically evaluated during specific intervals to achieve the mentioned characteristics. The Routine Test Interval (RTI) should be optimized in order to economically maximize the reliability of the prote...

More and more sub-stations are retrofitted with numerical relays, meters and monitoring devices. Most often, the older relay gets replaced with a newer relay with the rest of the installation such as Current Transformer (CT) and lead remaining undisturbed. Utilities have standardized on their older current transformers and want to maintain the same current transformer specifications throughout ...

In this paper, a new algorithm based on processing differential current harmonics is proposed for digital differential protection of power transformers. This algorithm has been developed by considering different behaviors of second harmonic components of the differential currents under fault and inrush current conditions. In the new method, a criterion function is defined in terms of the time v...

The aim of this paper is to extend a hybrid protection plan for Power Transformer (PT) based on MRA-KSIR-SSVM. This paper offers a new scheme for protection of power transformers to distinguish internal faults from inrush currents. Some significant characteristics of differential currents in the real PT operating circumstances are extracted. In this paper, Multi Resolution Analysis (MRA) is use...

This paper proposes a method to obtain a protected voltage gain by employing a protection circuit for the voltage doubler or multiplier circuit in an isolated tyde DC-DC Converter. The entire set up consists of a phase shift converter with a protected bridge/voltage doubler rectifier on the output side. The operating frequency of the phase shift converter is 20-25kHz (depending on the requireme...

protection systems have vital role in network reliability in short circuit mode and proper operating for relays. current transformer often in transient and saturation under short circuit mode causes mal-operation of relays which will have undesirable effects. therefore, proper and quick identification of current transformer saturation is so important. in this paper, an artificial neural network...

A new approach for protection of power transformer is presented using a time-frequency transform known as Wavelet transform. Different operating conditions such as inrush, Normal, load, External fault and internal fault current are sampled and processed to obtain wavelet coefficients. Different Operating conditions provide variation in wavelet coefficients. Features like energy and Standard dev...