Sandrine Le Ballois

Robust control of hybrid excitation synchronous generator for wind applications

The purpose of this paper is to develop a robust control law for a hybrid excitation synchronous generator (HESG) for wind power applications. In a HESG, the excitation flux is created by both permanent magnets and excitation coils, so the output voltage can be controlled by the DC excitation field. For isolated loads, it is then possible to use a very simple and reliable wind generator architecture composed only by a HESG, a rectifier and a DC/DC converter to control the excitation flux. However, the control of such a structure is not easy, especially if the system parameters are not well known. In this paper, the wind generator architecture is presented, modeled and simulated. The control is performed using a cascade control scheme: PI controller for the excitation current inner loop and H ∞ controller for the speed outer loop. The obtained results prove that robust control can be used for this architecture and can provide good dynamic responses despite large uncertainties on the electrical parameters.

Power operating domain of a cascaded doubly fed induction machine

The paper deals with the steady state operating limits of a cascaded doubly fed induction machine (CDFIM) in terms of active and reactive powers. An analytic method is suggested to derive the power region, in which the machine can operate safely without exceeding its rated parameters. The proposed steady-state analytical study has been thoroughly validated by simulations using an elaborated model of the CDFIM implemented on Matlab-Simulink. It is shown that the power capability is subject to several limitations. For a limited speed range the reactive power consumption and generation are determined by the stators current maximum values. The study is further extended to illustrate the effect of the slip range and the terminal voltage on the power limit curves.

Influence of rectifier and DC/DC converter on a hybrid excitation synchronous generator robust control for wind applications

The purpose of this paper is to study the influence of harmonics generated by a rectifier and a DC/DC converter on a robust and low-cost structure generator connected to an isolated load for wind applications. The machine used to convert mechanical power into electric power is a hybrid excitation synchronous generator (HESG). In this machine, the excitation flux is created by both permanent magnets and excitation coils, so the output voltage can be controlled by the DC excitation field. For isolated loads, it is then possible to use very reliable wind generator architecture, composed only by a HESG, a rectifier and a DC/DC converter to control the excitation flux. However, HESM are non-linear machines so, regarding their control, conventional controllers are not always sufficient to ensure a good stability and high performance. An H∞ controller is then used and designed assuming first harmonic hypothesis in order to control the wind generator in all the regions of the shaft output power versus wind speed curve. The effect of harmonics on the system robustness is then analyzed.

An experimental setup to study a hybrid drivetrain for a shunting locomotive

This paper presents a project for an experimental setup dedicated to the study of a hybrid traction drive for a shunting locomotive. Indeed, rail traction based upon hybrid technology is a very suitable solution for shunting locomotives, promising substantial benefits in terms of fuel savings, emissions and noise reductions. For instance, intensive tests carried out on various prototypes around the world demonstrated that the use of a hybrid locomotive, compared to a diesel equivalent with the same power, could save 40% to 70% of fuel, reduce NOx emissions up to 90%, reduce atmospheric particulate matter up to 70% and reduce CO2 emissions up to 60% while sulfur oxides would also decline. Significant reductions of noise and vibrations were also measured. Many companies have initiated projects on their own and developed prototypes but in most cases, information on these prototypes remains an industrial secret. To date, there is no unified approach or general theory for the hybrid traction principle applied to locomotives. The aim of the project presented in this paper is to lay the foundations for a general approach of a shunting locomotive hybrid drive train and its different components. The experimental setup will be there to confirm the theory. This research project gathers several partners who are in charge of different parts of the project.

A simple method for optimal control of PMSM with loss minimization including copper loss and iron loss

the goal of this paper is to present a comprehensive method to optimize the dq reference frame current of a permanent magnet synchronous machine (PMSM) including both copper and iron losses. The originality of the article concerns on the one hand the direct consideration of a resistance modeling iron loss in the circuit model and on the other hand the simplicity of the proposed method. In the paper, the circuit model is presented then the proposed control strategy is described. A method to compute the core loss resistance is also proposed. For a given machine the optimal references are computed and analyzed.

An integrated Matlab-Simulink platform for a wind energy conversion system based on a hybrid excitation synchronous generator

The purpose of this paper is to validate a control scheme of a wind turbine in its full operating range. In order to fully validate a chosen approach, it is usually necessary to perform experimental tests on a system. Fortunately, today, simulation can be a very efficient way to evaluate engineering solutions. Indeed, it is possible to perform very advanced simulations using a model sufficiently detailed to go entirely through the effects of interactions between many factors affecting the operation of the wind turbine. Failure to perform proper interconnection studies can lead to false conclusions regarding the controllers design and could endanger operations on the real system. Numerical simulation tools developed specifically for power systems and dynamic modeling may be used but general purpose modeling software such as Matlab-Simulink is well suited to the task. This paper presents an integrated Matlab-Simulink simulation platform for a robust control of a wind energy conversion system based on a hybrid excitation synchronous generator (HESG).