Abdallah Barakat

Analysis of synchronous machine modeling for simulation and industrial applications

This paper analyses the synchronous machine modeling by taken into account the machine parameters usually used in industry and those used in researcher’s domains. Two models are presented. The first one is developed in the (d, q) natural reference frames and the other one is referred to the (d, q) stator reference frame. To do this, two methods are proposed to compute the reduction factor of the field winding without any input from design information. It is shown that the reduction factors of the (d, q) damper windings do not influence on the terminal behavior of the machine. This means that it is possible to know the terminal behavior of the machine without knowing the real inductances and resistances of the damper windings. The accuracy of these models is validated by experimental tests.

Monovariable and Multivariable Voltage Regulator Design for a Synchronous Generator Modeled With Fixed and Variable Loads

This paper deals with the design and application of eight-linear voltage controllers that provide satisfactory voltage control performance in the presence of unknown load variation. The controller synthesis is based on the synchronous generator (SG) modeling strategy and the feedback control linearization method. Two models are presented. The first one takes into account a fixed load connected to the SG. The second model considers an unknown load. This consideration permits the design of a robust controller as regards the load variation. In addition, the linearization of the feedback control is established using a single-input-single-output controller and a multi-input-single-output (MISO) controller. The MISO solution represents a linearization method without any approximations. To validate the efficiency of each solution, the controllers are developed by using the H∞ method and implementation in a real-time domain is then performed.

Search for optimization of synchronous generator excitation machine by analyzing the rectifier commutation angle

A well known characteristic of a synchronous generator excitation drive is the large commutation overlap of the rotor side rectifier. A large value of the rectifier commutation angle adds an important non-linearity for synchronous generator control applications and increases the energy loss. In this paper, the variation of the commutation angle and the parameters that determine its magnitude are investigated using three types of excitation machine: a salient-pole permanent magnet synchronous machine and salient-pole wound field synchronous machine with and without damper windings. The results show the direct influence of the leakage fluxes and present the contribution of the q-axis damper windings. Experimental tests are presented and discussed. Some ways to optimize the excitation machine are also presented.

Direct control strategy of synchronous generators using DC/DC converter

The excitation system is the principal element that influences the dynamic behavior of alternators. This paper presents a new excitation structure based on a wound field synchronous machine (exciter machine), a diode bridge rectifier and a dc chopper. The proposed structure is associated to a H∞ voltage controller. The dynamic behavior of the synchronous generator is evaluated by experimental tests in the presence of unknown variations of the the power system operating conditions. Experimental results are presented and discussed.

A SISO H ∞ voltage controller associated with a PMG-thyristor excitation structure

This paper presents the contribution of the excitation structure consisted of a permanent magnet generator (PMG) and a thyristor bridge rectifier combined with a single input single output H∞ voltage controller. The proposed structure is compared to a standard industrial one consisted of a diode bridge supplied by a wound field synchronous machine and associated to an analog industrial controller. The modeling of the excitation structure, the main generator and the load variation, will be presented. The linearization of the global system and the feedback control will be also included. In addition, the implementation in real time domain and a comparison with the classical structure will allow us to show the efficiency of the proposed structure compared to the classical one as regards the reference tracking and perturbation rejection.

Identification of synchronous machine by Standstill Frequency Response (SSFR) method - influence of the stator resistance -

Development and success of Standstill Frequency Response method (SSFR) seen in recent years compared to other methods for parameter identification of electric machines in general and synchronous machines in particular, are well known. Nevertheless, certain problems and disadvantages are always problematic. Such that the error at low frequencies and the difficulty of measuring the stator resistance in direct current. In this paper, we propose a method to identify machine parameters using output error method and we highlight the influence of stator resistance value in the identification procedure of the synchronous machine parameters and precision from SSFR method.