Reza Katebi

Wind Turbine Control Using PI Pitch Angle Controller

Abstract This paper suggests two methods to calculate the gains of a proportional-Integral pitch angle controller for a 5 MW wind turbine. The first method is analytical and the second one is based on simulation. Firstly, the power coefficient characteristics for different pitch angles are calculated. Secondly, the output powers vs. rotor speed curves from cut-in to cut-out wind speeds are simulated. The results from first and second analyses used to find the control gains at different wind speeds. Finally, the results are compared using a wind turbine model to determinate turbines tracking characteristic.

Autonomous and decentralized mission planning for clusters of UUVs

This paper proposes an algorithm for autonomous strategic mission planning of missions where multiple unhabitated underwater vehicles (UUVs) cooperate in order to solve one or more mission tasks. Missions of this type include multi-agent reconnaissance missions and multi-agent mine sweeping missions. The mission planning problem is posed as a receding horizon mixed–integer constrained quadratic optimal control problem. This problem is subsequently partitioned into smaller subproblems and solved in a parallel and decentralized manner using a distributed Nash-based game approach. The paper presents the development of the proposed algorithm and discusses its properties. An application example is used to further demonstrate the main characteristics of the proposed method.

Robust multivariable tuning methods

A large number of tuning methods have been developed for automatic tuning of Single-Input Single-Output (SISO) PID controllers. Many industrial processes are however multivariable. It is possible to design and use decoupling compensators to reduce the loop interactions and then use SISO methods to tune the PID controllers. This will however need to be repeated when the process operating condition changes. Furthermore, decoupling methods work well only for systems with weak loop interactions. Despite the wide popularity and extensive research for SISO tuning methods, the number of tuning methods for Multi-Input Multi-Output (MIMO) systems is limited. The MIMO control loops may also be tuned sequentially using scalar techniques. This is not often sufficient since tuning a loop may detune other loops in the system. Some sequential tuning methods are partially open loop and only applicable to open-loop stable system. Furthermore these methods are time consuming, expensive and not easily accepted by the plant operators. This chapter reviews and discusses some easy to use practical multivariable methods and demonstrates their application to an industrial example.

Model-based fault detection and isolation for wind turbine

In this paper, a quantitative model based method is proposed for early fault detection and diagnosis of wind turbines. The method is based on designing an observer using a model of the system. The observer innovation signal is monitored to detect faults. For application to the wind turbines, a first principles nonlinear model with pitch angle and torque controllers is developed for simulation and then a simplified state space version of the model is derived for design. The fault detection system is designed and optimized to be most sensitive to system faults and least sensitive to system disturbances and noises. A multi-objective optimization method is then employed to solve this dual problem. Simulation results are presented to demonstrate the performance of the proposed method.

The control of specific actuators for fast ferry vertical motion damping

The vertical motions of fast ships, which have a negative effect on comfort and safety, can be attenuated using moving actuators. There is the need of a control strategy to move the actuators in the most convenient way, considering several objectives. The paper considers this problem, studying a practical real example. Experiments with a scaled down replica of a fast ferry has been done, first for modeling purposes and second for control studies. Linear control shows serious application problems. Taking this into consideration, a nonlinear control approach is devised, with satisfactory results.

State space stability analysis of unconstrained decentralized model predictive control systems

This paper analyzes stability properties of a decentralized MPC strategy. Assuming that control agents can exchange information with each other only once for every sampling interval, stability conditions on model and controller matrices are derived for the unconstrained case. Stability properties are analyzed either from a local or a global point of view and a comparison between the decentralized and the centralized control is introduced

ON-LINE ESTIMATION AND DETECTION OF ABNORMAL SUBSTRATE CONCENTRATIONS IN WWTPS USING A SOFTWARE SENSOR: A BENCHMARK STUDY

In this paper, a new approach for on-line monitoring and detection of abnormal readily biodegradable substrate (S S) and slowly biodegradable substrate (X S) concentrations, for example due to input of toxic loads from the sewer, or due to influent substrate shock load, is proposed. Considering that measurements of S S and X S concentrations are not available in real wastewater treatment plants, the S S | X S software sensor can activate an alarm with a response time of about 60 and 90 minutes, respectively, based on the dissolved oxygen measurement. The software sensor implementation is based on an extended Kalman filter observer and disturbances are modelled using fast Fourier transform and spectrum analyses. Three case studies are described. The first one illustrates the fast and accurate convergence of the extended Kalman filter algorithm, which is achieved in less than 2 hours. Furthermore, the difficulties of estimating X S when off-line analysis is not available are depicted, and the S S | X S software sensor performances when no measurements of S S and X S are available are illustrated. Estimation problems related to the death-regeneration concept of the activated sludge model no.1 and possible application of the software sensor in wastewater monitoring are discussed.

Graphical based predictive control design

Graphical programming provides a suitable way to design and configure advanced control applications. This paper illustrates the configuration of graphical model predictive control applications. The system in study is controlled with linear as well as nonlinear predictive control methods, and it demonstrates the convenience of a graphical interface for the development of these popular control design techniques. The system built uses the LabVIEW identification, control design optimisation and simulation toolkits for design verification and deployment. The control solutions can be easily imported to a real time platform for industrial applications. The predictive control with constrains is presented in details in this paper and its performance is illustrated in a case study. The example shows how graphical interface control design increases the reliability and robustness of the controller implementation

PID based control performance assessment for rolling mills: A multiscale PCA approach

This work is focused on exploring the use of Multi-scale Principal Component Analysis (MSPCA) for performance assessment and diagnosis of PID controllers in steel rolling processes. An optimal PID controller is used for performance benchmark. Diagnosis is implemented using an angle-classifier PCA-based approach. Theoretical framework of MSPCA, the performance index and the diagnosis procedure are developed. A procedure for implementing the proposed algorithm is presented. Simulations on the rolling mill roll force demonstrate reliable assessment and diagnosis results and practical use of the proposed method.

Shroud Design Criteria for a Lighter than Air Wind Energy System

Airborne Wind Energy (AWE) is a novel form of wind energy research looking to utilize the greater wind resource at higher altitudes. This paper focuses on a lighter than air system developed by Altaeros Energies. Using two force ratios the relationship between the buoyancy and aerodynamic force is related to the geometric parameters of the shroud. A dependence on a so-called area ratio is also shown relating the shrouds area to the shrouds throat area used as a reference for aerodynamic calculations. This ratio was varied in simulation and was found to have a marked effect on the driving forces over the shroud. Finally, an investigation into whether helium or hydrogen should be used for this application is shown. It is found that the design of the shroud has to be aerodynamically optimized for successful operation and that the choice of which gas to employ becomes one of safety rather than enhanced performance.