Search results for "Transformer"

Fibre-Optic Links For A Measurement And Control System At A HV Laboratory

1990

The paper presents a fibre-optic linking system for a measurement and control system installed at an industrial HV laboratory. The indirect voltage and current measurement system is furnished with the E0/0E transducers and FO links. The exploitation requirements on the adequate measurement accuracy and reliability have necessitated the inclusion of additional, digital PO link feedback from the computer control system. The proposed measurement system with the FO link has been installed at an HV laboratory transformer of an electric power station and successfully tested together with the overall equipment.

Angle Displacement Robust Controller for the Port Plate of the Hydraulic Transformer

2013

The hydraulic transformer is used in the hydraulic system to enhance the efficiency. However, how to control the angle displacement of the port plate is becoming a critical issue because of the new structure of the hydraulic transformer. This paper presents a new method for the angle displacement control system. Firstly, the basic principle of the system is presented. Then, the disturbance which is mainly the friction torque between the port plate and the cylinder block is calculated to estimate the range. Furthermore, the guaranteed cost control (GCC) is analyzed and combined with the disturbance and the characteristics of parameter uncertainties. Finally, the proposed control method is co…

Transient stability analysis for symmetrical and unsymmetrical faults in mixed three-phase and six-phase power systems

1989

Abstract The aim of this paper is to analyse the transient stability of a three-phase power system with six-phase lines interconnected by three-phase to six-phase transformers. For these mixed power systems a transient stability analysis is performed under all main types of disturbances (short-circuits, generator and load rejection, line outages), particularly in the case of faults at six-phase buses. A generalized procedure to evaluate transient stability is explained in detail. It is based on the symmetrical components method, which allows one to consider also unsymmetrical faults both at three-phase and six-phase buses. For every possible unsymmetrical short-circuit an equivalent fault a…

A Package for the Analysis of Automated MV Distribution Networks

2005

Experimental investigation on PLC signal crossing of power transformers

2014

In this work the use of PLC in MV-LV networks is investigated, by means of experimental tests in the case of a two-ways MV/LV communication between two secondary substations. The two substations are connected by a MV overhead power line. Moreover each substation has a by-pass connection at MV bus-bars and a MV/LV power transformer. A ST7580 transceiver is used to inject the communication signal. The transceiver is embedded in a new interface device developed by the authors. In the paper the communication issues are introduced and some experimental tests are presented and discussed. Such tests have been carried out in the presence of voltage net, i.e. 24 kV, with the aim to verify the possib…

Experimental EMF characterization of a secondary substation

2015

This paper presents the results of the experimental EMC characterization of a new medium/low voltage (MV/LV) secondary substation, which was developed in the framework of the research project "NEW CAB ELARC". It has two MV/LV transformers, with total rated power of 1000 kVA. To perform the experimental characterization, firstly an analysis was performed of the Italian and European standards recommendations. Different approaches were highlighted and the most appropriate procedures were identified for the measurement of the magnetic fields emissions, at power systems frequency (50 Hz) in steady-state conditions. A dedicated test lab was set up for the secondary substation characterization. Th…

A novel approach to current transformer characterization in the presence of harmonic distortion

2009

The current transformer (CT) performance under distorted waveform conditions is usually characterized by means of the frequency-response test. In this paper, a new way to characterize CTs, closer to real operation conditions, is proposed. The harmonic phase-angle and ratio errors are measured using a nonsinusoidal current composed of fundamental and one harmonic with adjustable phase shift. The new method was tested by determining the performance of two metering class CTs commonly used by the Italian power company. The errors measured using the proposed approach are larger than the ones obtained with the frequency response. This result suggests that the frequency-response approach for the e…

Oil filled MV/LV Power Transformer Behavior in Narrow Band Power Line Communication Systems

2012

The aim of this paper is to characterize oil-filled power transformers in the narrow-band power-line communication (PLC) frequency range of 50-150 kHz. A new model is proposed for such type of a transformer, in the aforementioned frequency range of interest, in order to study its influence on the signal transmission and to investigate the possibility that the PLC signal can cross the power transformer itself. The new model is simpler than those previously proposed in literature, and it can be used in the whole frequency range available for NB PLC according to the CENELEC EN 50065-1 A-band. In order to validate the model, simulation and measurement results are compared for four oil-filled po…

Design considerations for transformerless series resonant inverters for induction heating

2002

The aim of the paper is to present some preliminary ideas in order to overcome the output transformer in series resonant inverters for induction heating applications. By adding a third reactive element to the conventional two element resonant inverter, the output matching transformer can be eliminated, allowing accommodation of the resonant frequency and load with the only drawback being the need for an overdimensioning of the output capacitor bank, and benefiting from inherent short-circuit protection.

A DC current transformer for large bandwidth and high common-mode rejection

1999

A review of known magnetic-coupled current-sensing techniques is presented, Subsequently, a novel technique is introduced, based on a configuration discussed in a previous paper. The previous technique made use of a galvanomagnetic device (Hall effect sensor) to sense the magnetization of a current transformer core, so that the sum of the Hall voltage and the voltage across the secondary shunt resistor would yield a faithful copy of the input current. The technique described in this paper makes use of the same principle to obtain a high bandwidth (from DC to 1 MHz) and very high common-mode rejection current transformer, without the need for a Hall effect probe. This is achieved by subtract…