Stability enhancement of a hybrid micro-grid system in grid fault condition

Low voltage ride through capability augmentation of a hybrid micro-grid system is presented in this paper which reflects enhanced reliability in the system. The control scheme involves parallel connected multiple ac-dc bidirectional converters. When the micro-grid system is subjected to a severe voltage dip by any transient fault single power converter may not be able to provide necessary reactive power to overcome the severe voltage dip. This paper discusses the control strategy of additional power converter connected in parallel with main converter to support extra reactive power to withstand the severe voltage dip. During transient fault, when the terminal voltage crosses 90% of its pre-fault value, additional converter comes into operation. With the help of additional power converter, the micro-grid system withstands the severe voltage fulfilling the grid code requirements. This multiple converter scheme provides the micro-grid system the capability of low voltage ride through which makes the system more reliable and stable.peer-reviewe

Small signal stability analysis of doubly fed induction generator including SDBR

This paper presents small signal stability analysis of a doubly fed induction generator (DFIG) based wind farm including series dynamic braking resistor (SDBR) connected at the stator side. A detailed mathematical model of wind turbine, DFIG machine and converters and SDBR is presented in this paper to derive the complete dynamic equations of the studied system. Small signal stability of this system is carried out by modal and sensitivity analysis, participation factors and eigenvalue analysis. Finally, this paper presents an analysis of the dynamic behavior of DFIG based wind farm under voltage dip condition with and without SDBR.peer-reviewe

Simplified transfer functions of the brushless exciter of synchronous machines

A second order transfer function for the brushless exciter is studied. The step response can be oscillatory for some ranges of parameters, which are identified.Anglai

A simplified model of the rectifier-loaded synchronous machine with damper windings

Presents an idealized model of a round rotor, sinusoidally coupled, n-phase synchronous machine associated with a rectifier, the machine is fitted with two field circuits working also as damper windings and perfectly coupled with the armature.Anglai

Special effects on rectified output AC generators

The behaviour of rectified output AC generators can change very srongly with some features as saliency, space harmonics, etc. Two examples showing the new possibilities existing in this field are considered.Anglai

Commutation processes in polyphase commutatorless DC generators

The aim of this paper is to study the commutation processes in a polyphase rectified output generator with a DC type armature winding and a nearly rectangular field MMF. It is assumed that the mutual inductances between the different coils are a linear function of their relative position. This is a much more realistic assumption then the first harmonic one, and using a matrix formulation it leads to an analytical solution for the steady state behaviour from no load to short circuit. The theoretical results are very different from the ones given by the classical theory of rectification. They have been tested by experiments made on laboratory test machines.Anglai

Transfer function of rectified output AC generators

The field-armature small signal transfer function of a rectified output AC generator associated with an inductive load is worked out by linearizing the differential equations set of the system. The third order transfer function is used to calculate the frequency response of the system, the results are in good agreement with experimental measurements in various conditions. A simplified expression is proposed which is well adapted to the study of large power generators.Anglai

Contribution to the transient analysis of the self-controlled synchronous machine

The association of a synchronous motor and a load-commutated invertor can be considered as a drive system which is well adapted to high power levels, since a conventional thyristor bridge is triggered synchronously with the revolution of the rotor. Generally the detailed analysis of an association of that type is possible only by numerical simulation. The analysis of the behaviour of the drive in a more complex system necessitates simplified global models; such a dynamical model is developed in this communication.Anglai

Analysis of a new topology of flexible PCB winding for slotless BLDC machines

A significant improvement of slotless BLDC motor performance can be achieved by printing their windings on flexible printed circuit board (PCB). In comparison with windings made from copper wire, they may have more complex shapes in addition to a variable conductor cross-section along the winding loops. This paper presents a new winding topology taking the best of the capabilities offered by the flexible PCB technology and compare this to two existing topologies. It shows that a gain factor of about 10% on the motor performance can be reached with the new topology, confirming the high potential of the flexible PCB technology

Torque-to-Weight Ratio Maximization in PMSM Using Topology Optimization

This paper focuses on the maximization of the torque-to-weight ratio of permanent magnet synchronous motors (PMSM) using a topology optimization method. It aims at finding the optimal design that either maximizes the torque for a given weight or minimizes the weight for a required torque. The analysis presented in this paper besides considers radial and tangential permanent magnets. The paper shows that the optimization always leads to the same optimal motor topology, which is scaled to achieve the required torque. In addition, a scale law is highlighted for computing the PMSM torque according to its size and is used to plot a Pareto curve that provides the achievable torque-to-weight ratio according to the motor weight