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This paper deals with the model-based nonlinear control design for wind turbines in the full load region using Takagi-Sugeno techniques. The generator torque of the wind turbine is considered as a varying parameter of the system, which is adjusted by an external operator. This enables the possibility to provide ancillary services. The highly nonlinear behavior of the wind turbine is handled by the...
A new approach for optimal observer design of nonlinear systems, the so-called Nonlinear Quadratic Estimator is proposed. This approach employs the minimisation of a quadratic cost functional, thereby comprising two design parameters: Selective weighting of specific error state components and estimated upper bound minimisation. The new approach works without dual system transformation, achieving significant...
This paper presents a dynamic modeling and simulation of a small wind turbine connected to a Permanent Magnet Synchronous Generator PMSG, which is controlled by a Zero d-axis current (ZDC) control scheme. The model of the wind turbine system is developed using basic mathematical equations and it is carried out using the Matlab /Simulink environment. The simulation results demonstrate the effectiveness...
It's a modeling of a small Variable Speed Wind Turbine coupled to a multi-pole permanent magnet synchronous generator to supply a DC Load. The aerodynamic model converts the kinetic power of the wind into a mechanical power illustrated in a rotational speed of the rotor and transmitted to the generator by a rigid shaft of one degree of freedom, it's the model of a gearless one masse drive train connected...
In this paper, a two-layer fault detection and isolation (FDI) scheme with application in wind turbines is presented. Commonly, model-based FDI concepts use a suitable mathematical model of the plant as a redundancy for on-line available data such as measurements and control outputs. In addition, the proposed two-layer concept exploits the redundancy between component and structure models at their...
This paper analyses the observer synthesis for a class of nonlinear systems represented by Takagi-Sugeno models with premise variables depending on unmeasurable system states. It is well known that in case of unmeasurable premise variables the time-varying difference of the membership functions with true and estimated premise variables has to be considered in general as external disturbances or unknown...
The reliability and functional safety of electrical drives is necessary for the use in safety-related systems such as electrical cars and aerospace applications. In this paper, a rotor flux oriented fault tolerant control scheme for induction machines with squirrel-cage rotor using the fault hiding approach is presented. Based on a proposed physical model of the induction machine in Takagi-Sugeno...
This paper studies the input-to-state stability (ISS) of nonlinear systems in Takagi-Sugeno's form. Following the definitions and ISS properties proposed by Sontag and Wang [1], a condition in terms of Linear Matrix Inequalities (LMIs) and predefined norm-bounded inputs is derived. Due to the convex property of the weighted sum of input matrices, the input field is bounded and the ISS property holds...
In this paper, two criteria for robust actuator fault reconstruction with sliding mode observation for a class of uncertain nonlinear systems are derived. It is known, even though the sliding mode technique is robust against unknown but bounded uncertainties, that the quality of fault reconstruction under real conditions is not as good as assumed in the design stage. This is often due to the fact...
Frequently, the increasing level of automation requires a systematic consideration of numerous interacting components influenced by internal feedback mechanisms as well as interactions with human operators under varying environmental conditions. This places demands on modeling, which in general cannot be satisfied by traditional modeling concepts. In this paper, a model approach for complex technical...
A nonlinear control-oriented description of large scale wind turbines with hydrostatic transmission using convex weighted combination polytopic models is proposed. The complete mathematical model of a wind turbine takes into consideration the nonlinearity of the aerodynamic maps and the hydrostatic drive with variable displacement pump and variable displacement motor. The objectives of the model-based...
In this paper, a Takagi-Sugeno sliding mode observer is designed to detect, isolate and reconstruct three different sensor faults and an actuator fault in a specified wind turbine benchmark problem. An extension of the discontinuous observer term using a weighted combination of gains responsible for establishing the sliding motion is proposed. The weights are equivalent to the membership functions...
In this paper, Lyapunov-based stability criteria for Takagi-Sugeno models in a new coordinate system are derived. Two different cases are considered: First, a simple change of coordinates with a common similarity transformation matrix for each local model is considered. For this, a linear matrix inequality (LMI) stability criterion for the transformed system based on the original coordinates is presented...
A Takagi-Sugeno sliding mode observer (TS SMO) is used to reconstruct actuator faults in wind turbines. Since the two control signals, the pitch angle and the generator torque, are of significantly different orders of magnitude, a TS SMO with a weighted switching action is used. For the nonlinear full-load region, a TS controller based on linear LQR control designs is used, where the stability is...
In modern wind turbines the output power for wind speeds above the nominal wind speed is limited by the adjustment of the rotor blade angles. The adjustment is performed with the pitch system. For cost reasons, in small wind turbines simple mechanical pitch systems are used actuated by centrifugal force and thus depending on the rotor speed and the blade mass. With the help of the converter the generator...
To improve the dynamics in mechatronic systems an active friction compensation is usualy necessary. However, a poor friction compensation action in the control scheme may lead to significant tracking errors, especially at low velocities.
The performance and reliability of pitch control systems significantly influences the functional safety of wind turbines. In this paper, an observer-based fault detection approach for a class of nonlinear systems, which can be modeled as Takagi-Sugeno (TS) fuzzy models, is presented and applied to electro mechanical pitch drive systems of wind turbines. To achieve robustness we propose a TS fuzzy...
For a horizontal-axis wind turbine (HAWT), a dynamic nonlinear model with four degrees of freedom is derived and transformed into a Takagi-Sugeno (TS) model structure using the sector nonlinearity approach. Thereby, an exact transformation of the nonlinear model is obtained as a weighted combination of linear models. This structure allows for a convenient design of controller and observer structures...
Power-split continuously variable transmissions (CVTs) represent a promising technology to improve the fuel economy of high-power off-road vehicles such as construction and agricultural machines. Power-split CVTs are capable of keeping the combustion engine running within the optimal range in terms of fuel economy and performance. There are characterized by the combination of a traditional mechanical...
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