Sung-ho Hur

Modeling and Control of a Plastic Film Manufacturing Web Process

This paper is concerned with the modeling of a plastic film manufacturing process and the development and implementation of a model-based Cross-Directional (CD) controller. The model is derived from first-principles and some empirical relationships. The final validated nonlinear model could provide a useful offline platform for developing control and monitoring algorithms. A new controller is designed which has a similar structure to that of Internal Model Control (IMC) with the addition of an observer whose gain is designed to minimize process and model mismatch. The observer gain is obtained by solving a multiobjective optimization problem through the application of a genetic algorithm. The controller is applied to the nonlinear model and simulation results are presented demonstrating improvements that can be achieved by the proposed controller over two existing CD controllers.

Using Improved Power Electronics Modeling and Turbine Control to Improve Wind Turbine Reliability

Improving offshore wind turbine reliability is a key industry goal to improve the availability of this renewable energy generation source. The semiconductor devices in the wind turbine power converter are traditionally considered as the most sensitive and important components to achieve this and managing their thermomechanical stressing is vital, since this is one of their principal long-term aging mechanisms. Conventional deterministic reliability prediction methods used in industrial applications are not suitable for wind turbine applications, due to the stochastic nature of the wind speed. This paper develops an electrothermal model of the power devices, which is integrated with a wind turbine system model for the investigation of power converter thermal cycling under various operating conditions. The model has been developed to eliminate the problems of pulse width modulation switching, substantially reducing simulation time. The model is used to improve the current controller tuning method to reduce thermal stresses suffered by the converter during a grid fault. The model is finally used to design a control method to alleviate a key problem of the doubly fed induction generator-severe thermal cycling caused during operation near synchronous speed.

A control and monitoring oriented model of a film manufacturing process

Abstract This paper describes the development of a control and monitoring oriented model of a plastic film manufacturing process. The model is mainly derived from first-principles and has been implemented in the Matlab/Simulink dynamic simulation environment. The development of the model forms the first phase of a project that aims to develop a nonlinear sub-space based monitoring, fault detection and trouble shooting system for the film manufacturing process.

Control oriented modelling of a wind turbine and farm

The Matlab/Simulink model of the Supergen (Sustainable Power Generation and Supply) Wind 5 MW exemplar wind turbine, which has been employed by a number of researchers at various institutions and Universities over the last decade, is improved, especially in speed, to facilitate wind farm modelling. Note that wind farm modelling usually involves duplicating wind turbine models, hence the speed of each turbine model is critical in wind farm modelling. The objective is achieved through various stages, including prewarping, implicit and explicit discretisation, and conversion to C. Simulation results are presented to demonstrate that improvement in speed is significant and that the resulting wind turbine model can be used for wind farm modelling more efficiently. It is important to highlight that improvement in speed is achieved without compromising the complexity of the turbine model; that is, each turbine included in a wind farm is not simplified or compromised.

Model predictive control of a variable-speed pitch-regulated wind turbine

The Model Predictive Controller is designed for a 5MW variable-speed pitch-regulated wind turbine for three operating points - below rated wind speed, just above rated wind speed, and above rated wind speed. At each operating point, the controllers are designed based on two different linear models of the same wind turbine to investigate the impact of using different control design models (i.e. the model used for designing a model-based controller) on the control performance.

Gusts detection in a horizontal wind turbine by monitoring of innovations error of an extended Kalman filter

This paper presents a novel model-based detection scheme capable of detecting and diagnosing gusts. Detection is achieved by monitoring the innovations error (i.e., the difference between the estimated and measured outputs) of an extended discrete Kalman filter. It is designed to trigger a detection/confirmation alarm in the presence of wind anomalies. Simulation results are presented to demonstrate that both operating and coherent extreme wind gusts can successfully be detected. The wind anomaly is identified in magnitude and shape through maximum likelihood ratio and goodness of fit, respectively. The detector is capable of isolating extreme wind gusts before the turbine over speeds.

Robust Nonlinear Generalised Minimum Variance control

This paper extends the Nonlinear Generalised Minimum Variance (NGMV) controller in order to improve the robustness of its control or set-point tracking performance. This is achieved by replacing the Kalman filter included in the original NGMV controller with an observer whose gain is obtained to minimise the effect of uncertainty, which includes unknown disturbance, modelling error, and faults. The performance of the extended controller is assessed and compared with the original controller by application to a nonlinear tank model and a cam phaser dynamics model, and simulation results are presented in this paper demonstrating improvements that can be achieved by the extended controller over the original controller.

Model-based controller design for a plastic film extrusion process

This paper reports the development and implementation of a model-based cross-directional controller for plastic film extrusion and other web-forming processes. The controller design has a similar structure to that of internal model control (IMC) with the addition of an observer whose gain is designed to minimise process and model mis-match. The observer gain is obtained by solving a multi-objective optimisation through the application of a genetic algorithm and simulation results are presented in this paper demonstrating improvements that can be achieved by the proposed controller over two existing CD controllers.