Emile Mouni

Synchronous Generator Output Voltage Real-Time Feedback Control via

A new approach on synchronous generator (SG) output voltage control is presented. The originality of such a strategy is based on the excitation structure that integrates a permanent-magnet generator combined with a modern control method: the H infin. The main motivation of this paper is the debatable results obtained with the classical excitation structure controlled by a traditional PID controller. The SG model as well as the control strategy will be presented. The implementation in real time domain and a comparison with the classical structure will allow us to prove the efficiency of the proposed structure compared to the classical one as regards the reference tracking and signal quality.

H_\infty

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.

Strategy

In this paper, a technique for estimating the synchronous machine’s parameters using sudden short circuit test, is proposed. Before implementing estimation algorithms, a special method of the machine modelling is given. This last one allows to perform tests such as short-circuit, load impact and shedding test, in an easier way than the models usually developed in the literature. Thanks to the well known electrical equivalent circuit of the generator, the relationships between parameters generally used in the industry (i.e., reactances and time constants) and those used in researcher’s domains will be given. Finally, simulation results of the proposed method, allows to show that the algorithm is capable of providing very good estimated parameters fitting with the actual parameters.

Analysis of synchronous machine modeling for simulation and industrial applications

This paper aims to present three different methods of synchronous generator modelling. The first one is based on electrical scheme and it uses a Parks framework thanks to the Parks matrix. The two others use state space modelling strategy. The difference between these last two models is the load which can be or not be incorporated in the generator model. The comparison results with experiment, presented at the end of this paper allows to choose the one which suits the best to tests generally performed on synchronous generator

Synchronous generator modelling and parameters estimation using least squares method

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.

Comparative study of three modelling methods of synchronous generator

The paper mainly deals with the synchronous generator output voltage control by using a non linear control strategy: the sliding mode. The originality is not only due to the involved control strategy but also the use of a voltage source for the machinepsilas excitation and thyristors bridge. The favourable arguments to the sliding mode control are decoupling design procedure and easy implementation by power converters. The system stability is ensured by using a Lyapunov function. Thanks to the new excitation system based on voltage source, the systempsilas dynamics is improved in spite of the chattering phenomena induced by the sliding mode control. Simulations are done with Matlab/Simulinktrade and a discussion on the results is exposed at the end of the paper.

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

A modern strategy is applied to the control of the synchronous generator output voltage: the generalized predictive control. Then a complete discrete-time multi-variable predictive controller is used. Before implementing such a controller a particular method of synchronous generator modelling is presented. This last one is very suitable when tests are to be performed to validate or identify the model. In order to optimize the controller design and to make its implementation in real time domain easier, a reduction of the model order has been achieved. The simulation results presented at the end of the paper illustrate the efficiency and the handiness of the obtained controller in spite of the complexity due to the computation algorithm.

Improvement of synchronous generator’s transient state by using voltage source and sliding mode control

In this Paper, we present a systematically method based on the transformer coupling effect to establish the d-and q-axes equivalent circuits, which can describe the transient behavior of the synchronous machine. The MATLAB/Simulink Power System Blockset tools (PSB) is used for the simulation of synchronous machines by their equivalent circuits. One used an empirical method, based on the comparison between the practical and numerical results, to elaborate an improved synchronous machine model during dynamic behaviors.

Synchronous generator output voltage control via a generalized predictive R S T controller

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.

A Method to Improve the Synchronous Machines Equivalent circuits

The influence of constant speed wind turbine in an electrical network during torque impact can lead various problems. The disturbances affect active power quality, reactive power and r.m.s. phase to phase voltage. In this paper, we propose an original system and control to solve firstly, the problems due to the brutal impact of active power and secondly the control of reactive power. The principle of the proposed wind energy system with STATCOM-supercapacitors energy storage is to limit the rapid variation of active power and give the required reactive power compensation to the induction machine during the torque change. The supercapacitor is directly coupled to the common dc-link of the whole bidirectional DC-AC converter. The control strategy of the STATCOM use a Linear Matrix Inequalities (LMIs) technic to regulate the currents injected or absorbed by the inverter. The same strategy is used to control the variable DC supercapacitor voltage. The simulation results of the STATCOM using a state-feedback with integral controller for id, iq currents converter and a simple proportional (Kp) controller cascaded to d axis current loop for DC voltage source are presented and discussed.