Stabilization of Uncertain Systems using Backstepping and Lyapunov Redesign

This article presents stabilization method for uncertain system using backstepping technique and Lyapunov redesign. The design begins by obtaining stabilizing function for unperturbed system using control Lyapunov function. As such, the stabilizing function guarantees asymptotic stability in the sense of Lyapunov. The control Lyapunov function is re-used in the re-design phase whereby the nonlinear robust function is then augmented with pre-designed stabilizing function for robustness toward uncertainties. Lyapunov redesign is used in designing overall robust stabilizing function which guarantees asymptotic stability toward uncertainties and also toward any perturbed states within asymptotic stability region

Identification and Simulation of Dc-Dc Boost Converter for Charging Up PV Voltage for 24-Volts Battery

This manuscript is a piece of report on the identification of a DC-DC Boost switched mode converter for charging up Photovoltaic (PV) voltage for 24-volts battery. A DC-DC Boost converter with unknown mathematical characteristic is identified using Auto-Regressive with Exogenous Input (ARX) model. The identification of such DC-DC converter, on the basis of recorded data from PV is conducted to obtain the mathematical model of the converter. The knowledge about the converter is then beneficial for the design process of a PV’s maximum power point tracking (MPPT) system. The identification process that exploits the advantage of linear parametric ARX gives beneficial information such as correlation, best fit and poles-zeros location. The purpose of identification is to obtain the best model of the converter and hence, beneficial the simulation and controller design phase which include the MPPT

Realization of Real-Time Hardware-in-the-Loop for a Liquid Level with Open-loop Ziegler Nichols Technique

This paper presents the realization of a real-time hardware-in-the-loop (HIL) for a liquid level control system. Multifarious controllers that were proposed in the previous literature are constrained within simulation platform. Several advanced control configurations are implemented in the hard-wire platform that incurs complex programming and requires computational burden. These kind of control configurations do not permit the operator to tune the control parameter online. Moreover, the parameters inside the microcontroller are unobservable to the operators. As such, the need to implement a real-time HIL for a liquid level control system worthwhile to the operators. It gives intuitive configuration and user-friendly application to the operators because the tuning process can be implemented in didactic manner. Furthermore, the controller design phase can be conducted with lees programming burden. Implementing the HIL requires three phases. The tank must be calibrated to obtain a linear relationship between the voltage and the water level. Afterward, the open-loop Ziegler Nichols is exploited to tune the parameters of three term Proportional-Integral-Derivative controller. The controller is then implemented in the MATLAB SIMULINK platform in the host computer. The result shows that the proposed real-time configuration guarantees the asymptotic tracking of the demanded water level with only  steady state error

Estimator and Controller Design for a Didactic Liquid Level system by System Identification Approach

This manuscript is a piece of report on the identification of Didactic Liquid Level Systems. The term didactic is used as to enlighten the purpose of proto-typing liquid level system for educational use. A liquid level system with unknown mathematical characteristic is identified using ARX (Auto-Regressive with Exogenous Input) model. The determination of such system, on the basis of experimental data is conducted to obtain the discrete transfer function as well as state space representation of it. The identification process which exploits the advantage of linear parametric ARX gives beneficial information such as correlation, best fit and poles-zeros location. The Linear Quadratic Regulator (LQR) is tested for such liquid level system before the estimator is designed. Literal analysis of the estimator performance is conducted as a preliminary insight to the next investigation on the self tuning Proportional – Integral – derivative (PID) algorithm

Power Stabilization Of A Stand-Alone Solar System Using Perturb and Observe MPPT Algorithm

Solar energy is gaining more popularity for the choice of electricity generation as it is available everywhere especially in Malaysia and it is free to harness. This paper presents the method of power stabilization of a stand-alone solar system using perturb and observe (P&O) maximum power point algorithm. The PV module is modeled based on the parameters obtained from a commercial PV data sheet. A DC-DC boost converter is chosen to step up the input DC voltage of the PV module while the perturb and observe maximum power point algorithm is used and modeled to ensure the power stabilization is made. The model is simulated under a constant of solar irradiance and temperature in which follow the standard test condition (STC). The comparison between including and excluding of MPPT controller is also made and results show that the model yields the different performance

Variable speed wind turbine with external stiffness and rotor deviation observer

Often in prominent literature, the appearance of external stiffness in wind turbine dynamical model has been neglected. The ignorance of external stiffness eliminates the presence of rotor-side angular deviation in the system dynamic. In order to give more practical look of the variable speed control system structure, we develop a linear observer to estimate the rotor angular deviation. We use Linear Quadratic Regulator (LQR) to design the observer gain, as well as the estimation error gain. To facilitate observer design, the system is linearized around its origin by using Jacobian matrix. By using the estimated rotor angular deviation, we design a variable speed control via Lyapunov and Arstein to enhance power output from the turbine

Robust bounded control for uncertain nonlinear systems: application to a nonlinear strict feedback wind turbine model with explicit wind speed dynamics.

In this paper, a robust bounded control law for a class of uncertain nonlinear systems is proposed. The proposed bounded controller guarantees asymptotic stability, asymptotic tracking and asymptotic disturbance rejection of systems in strict feedback form with the sum of unmatched uncertainties and the unbounded exogenous disturbance. A feedback law emerged from Artstein's Theorem and Sontag's universal formulas are known to be useful to limit the control signal. However, the formulas are not robust as in many cases, being applied to the systems without uncertainties and disturbances. The controller proposed in this paper takes advantages of a mixed backstepping and Lyapunov redesign, which employed to enrich the Sontag's universal formulas. Therefore, the appealing feature of the proposed controller is that it satisfies small control property in order to preserve performance robustness and stability robustness with less control effort. Another advantage of the proposed controller is the formulas become applicable to higher order systems (i.e. order > 0). This paper also discusses fuzzy logic tuning approach for the controller parameters such that the closed loop system matrix remain Hurtwitz. For practicality, the proposed technique is applied to a variable speed control of a new strict feedback wind turbine system with wind dynamics appeared explicitly in the system model. The proposed controller guarantees the asymptotic tracking of the turbine rotor speed; maintains the optimal tip speed ratio and produces maximum power coefficient. This yields maximum power output from the turbine

Average dynamical frequency behaviour for multi-area islanded micro-grid networks

A micro-grid is a part of power system which able to operates in grid or islanding mode. The most important variable that able to give us information about the stability in islanded micro-grid network is the frequency dynamical responses. The frequency analysis for multi-area micro-grid network model may involve a complicated of mathematical equations. This makes the researcher intending to omit several unnecessary parameters in order to simplify the equations. The purpose of this paper is to show an approach to derive the mathematical equations to represent the average behavior of frequency dynamical responses for two different micro-grid areas. Both of networks are assumed to have non-identical distributed generator behavior with different parameters. The prime mover and speed governor systems are augmented with the general swing equation. The tie line model and the information of rotor angle was considered. Then, in the last section, the comparison between this technique with the conventional approach using centre of inertia (COI) technique was defined

A Review On SVC Control For Power System Stability With And Without Auxiliary Controller

Since the beginning of the last century, power system stability has been recognized as a vital problem in securing system operation. Power system instability has caused many major blackouts. This paper reviewed the previous technical works consisting of various methods of optimization in controlling power system stability. The techniques presented were compared to optimize the control variables for optimization of power system stability. Power system stability enhancement has been investigated widely in literature using different ways. This paper is focusing on SVC performance for enhancing power system stability either through SVC controlled itself or SVC controlled externally by other controllers. Static VAR compensators (SVCs) are used primarily in power system for voltage control as either an end in itself or a means of achieving other objectives, such as system stabilization. The analysis on performance of the previous work such as advantages and findings of a robust method approach in each technique was included in this paper