Intriguing mal-operations and fail-to-trip of the differential protection of the converter transformer in the HVDC system are reported. In this paper, the mechanism of these abnormal operation behaviors is analyzed. By virtue of deliberately designed models of the converter transformer and the HVDC transmission system, a variety of simulation tests are carried out and above mentioned strange op...

Abstract: In this paper, a new topology is developed for a three-phase four-wire (3P4W) distribution system utilizing a zig-zag transformer along with three-phase threewire (3P3W) Unified Power Quality Conditioner (UPQC).In this proposed topology the neutral point of the star connected transformer, used for the connection of series active power filter (APF) of 3P3W UPQC, is utilized as a fourth...

The presented high-voltage DC source was designed to enable laboratory measurements of reverse and forward characteristics in non-conducting state of power semiconductor components. It also enables to measure the minimum triggering current or control voltage in dependence of the voltage on main electrodes for SCR, triac or voltage-controlled semiconductor devices such as MOSFET and IGBT, respec...

The subscriber line interface circuit (SLIC) provides DC power, ringing and supervision functions for the "plain old telephone service" (POTS) where alerting a telephone is a prerequisite but a central ringer is generally not available. SLICs have also been used in Terminal Adapters (TA), Voice over Internet Protocol (VoIP) and Network Termination (NT) applications. This application note provid...

Level shifters play critical roles in ultra low-voltage circuits and systems. a new low power level shifter (LS) is presented for robust logic voltage shifting from near/sub threshold to above threshold domain. The new circuit combines the multi threshold CMOS technique along with novel topological modifications to guarantee a wide voltage conversion range with limited static power and total en...

Transformer fault diagnosis and repair is a complex task that includes many possible types of faults and demands special trained personnel. In this paper, Petri Nets are used for the simulation of transformer fault diagnosis process and the definition of the actions followed to repair the transformer. An oil thermometer and a Buchholz relay are used for transformer fault detection. Simulation r...

The paper presents common mode voltage analysis of single phase grid connected photovoltaic inverter. Many researchers proposed different grid tie inverters for applications like domestic powering, street lighting, water pumping, cooling and heating applications. Traditional grid tie PV inverter uses either a line frequency or a high frequency transformer between the inverter and grid. The tran...