A Lyapunov-Function Based Control For A Three-Phase Shunt Hybrid Active Power Filter

The denomination Power quality by and large refers to maintaining approximal sinusoidal power distribution bus voltage at rated magnitude and frequency. This is mainly affected by the generation of harmonics. Even though electronic and non-linear devices are flexible, economical and energy efficient, they may degrade power quality by creating harmonic currents and consuming excessive reactive power. A family of various shunt hybrid active power filters has been explored in shunt and series configurations to compensate for different types of nonlinear loads. They provide controlled current injection to remove harmonic current from the source side of electric system and also can improve the power factor

A Hybrid Active Filter Using the Backstepping Controller for Harmonic Current Compensation

This document presents a new hybrid combination of filters using passive and active elements because of the generalization in the use of non-linear loads that generate harmonics directly affecting the symmetry of energy transmission systems that influence the functioning of the electricity grid and, consequently, the deterioration of power quality. In this context, active power filters represent one of the best solutions for improving power quality and compensating harmonic currents to get a symmetrical waveform. In addition, given the importance and occupation of the transmission network, it is necessary to control the stability of the system. Traditionally, passive filters were used to improve energy quality, but they have endured problems such as resonance, fixed remuneration, etc. In order to mitigate these problems, a hybrid HAPF active power filter is proposed combining a parallel active filter and a passive filter controlled by a backstepping algorithm strategy. This control strategy is compared with two other methods, namely the classical PI control, and the fuzzy logic control in order to verify the effectiveness and the level of symmetry of the backstepping controller proposed for the HAPF. The proposed backstepping controller inspires the notion of stability in Lyapunov’s sense. This work is carried out to improve the performance of the HAPF by the backstepping command. It perfectly compensates the harmonics according to standards. The results of simulations performed under the Matlab/Simulink environment show the efficiency and robustness of the proposed backstepping controller applied on HAPF, compared to other control methods. The HAPF with the backstepping controller shows a significant decrease in the THD harmonic distortion rate

Simulation and Performance Evaluation of Shunt Hybrid Power Filter for Power Quality Improvement Using PQ Theory

This work proposes the design of shunt hybrid filter using instantaneous power theory to improve the power quality and simulation has been carried out for 3 phase distribution system feeding different types of non linear loads. The proposed filter consists of parallel combination of 5th and 7th tuned selective harmonic elimination passive filters, which is connected in series with a small rating IGBTs based voltage source inverter. In this work, principle of compensation and filtering behavior of the system has been discussed in detail. Instantaneous real and reactive power theory based controller has been designed to estimate the reference current from the distorted current. In order to reduce the harmonics, generated reference currents are tracked by voltage source inverter using hysteresis band current controller. The performance of the hybrid scheme is evaluated for various nonlinear loads using Matlab/ Simulink tool. The detailed analysis has been carried out on harmonics reduction and DC bus voltage regulation and the simulation result ensures the feasibility of suggested control strategy. The proposed topology improves the filtering performance of the passive filter in hybrid scheme

Nonlinear constrained and saturated control of power electronics and electromechanical systems

Power electronic converters are extensively adopted for the solution of timely issues, such as power quality improvement in industrial plants, energy management in hybrid electrical systems, and control of electrical generators for renewables. Beside nonlinearity, this systems are typically characterized by hard constraints on the control inputs, and sometimes the state variables. In this respect, control laws able to handle input saturation are crucial to formally characterize the systems stability and performance properties. From a practical viewpoint, a proper saturation management allows to extend the systems transient and steady-state operating ranges, improving their reliability and availability. The main topic of this thesis concern saturated control methodologies, based on modern approaches, applied to power electronics and electromechanical systems. The pursued objective is to provide formal results under any saturation scenario, overcoming the drawbacks of the classic solution commonly applied to cope with saturation of power converters, and enhancing performance. For this purpose two main approaches are exploited and extended to deal with power electronic applications: modern anti-windup strategies, providing formal results and systematic design rules for the anti-windup compensator, devoted to handle control saturation, and “one step” saturated feedback design techniques, relying on a suitable characterization of the saturation nonlinearity and less conservative extensions of standard absolute stability theory results. The first part of the thesis is devoted to present and develop a novel general anti-windup scheme, which is then specifically applied to a class of power converters adopted for power quality enhancement in industrial plants. In the second part a polytopic differential inclusion representation of saturation nonlinearity is presented and extended to deal with a class of multiple input power converters, used to manage hybrid electrical energy sources. The third part regards adaptive observers design for robust estimation of the parameters required for high performance control of power systems

Improved predictive current model control based on adaptive PR controller for standalone system based DG set

This paper investigates an improved current predictive model control (PCMC) strategy with a prediction horizon of one sampling time for voltage regulation in standalone system based on diesel engine driven fixed speed of a synchronous generator. An adaptive PR controller with anti-windup scheme is employed to achieve high performance regulation without saturation issues. In addition, new method to obtain the optimal parameters of the adaptive PR controller to achieve high performance during the transition and in steady state is provided. To balance the power at the point of common coupling (PCC) as well as to feed a clean power to the connected loads, a three-phase voltage source inverter (VSI) with LRC filter is controlled using the developed improved PCMC strategy, where the output filter current is controlled using the predicting of the system behaviour model in the future step, at each sampling prediction time. The performances of the proposed configuration and the improved control strategy are verified using Matlab/Simulink interface

Analysis and sliding mode control of four-wire three-leg shunt active power filter

In this paper, the analysis and the sliding mode control application for a shunt active filter is presented. The active filter is based on a three-leg split-capacitor voltage source inverter which is used to compensate harmonics and unbalance in the phase currents, and therefore to cancel neutral current. The proposed sliding mode control is formulated from the multivariable state model established in dq0 frames. The selection of the sliding mode functions takes in account simultaneously, the current tracking and the dc-bus regulation and balancing, without the need of outer loops for the dc-bus control. A particular attention is given to the sliding mode functions design in order to optimize the convergence of the zero-sequence error and the dc-bus voltage unbalance. The effectiveness of the proposed control has been verified through computer simulation where satisfactory results are obtained over different conditions

A hybrid fuzzy sliding-mode control for a three-phase shunt active power filter

This document is the Accepted Manuscript version of the following article: Mohamed Abdeldjabbar Kouadria, Tayeb Allaoui, and Mouloud Denai, ‘A hybrid fuzzy sliding-mode control for a three-phase shunt active power filter’, Energy Systems, Vol. 8 (2): 297-308, March 2016. The final publication is available at Springer via http://dx.doi.org/10.1007/s12667-016-0198-4.This paper describes the hybrid fuzzy sliding-mode control (HFSMC) for a three phase shunt active shunt filter for the power quality improvement. The Power Quality (PQ) problems in power distribution systems are not new but only recently the effects of these problems have gained public awareness. These non-linear loads are constructed by nonlinear devices in which the current is not proportional to the applied voltage. For the harmonic elimination different methods are used, but in this paper a novel fuzzy logic controller for a three-phase shunt active power filter for the power quality improvement such as reactive power and harmonic current compensation generated due to nonlinear loads. The hybrid fuzzy sliding-mode control (HFSMC) approach is proposed such that it can be applied with advantages to both fuzzy and sliding-mode controller. Simulation results are presented to demonstrate the effectiveness of the control strategy. The results are found to be quite satisfactory to mitigate harmonic distortions, reactive power compensation and power quality improvement.Peer reviewedFinal Accepted Versio

Study and RTDS implementation of some controllers for performance and power quality improvement of an induction motor drive system

The present research work is directed to study of some controllers for design, modelling, simulation and RTDS implementation of induction motor (IM) drive system to identify suitable controller for high performance.Initially dynamic modelling and simulation of a feedback linearization scheme for high performance IM drive is carried out. The flux measurement required in this scheme is achieved using flux estimator rather sensor to simplify the system. The complexity and calculation involved in reference frame transformation is taken care by implementing the scheme in stationary reference frame. Two linear and independent subsystems: (i) Electrical and (ii) Mechanical are created by linearizing control scheme. The systematic design of closed loop control scheme using Proportional Integral (PI) controller is developed for implementation. To take care of uncertainties in the system the Fuzzy controller is added to speed controller. Sliding Mode (SM) controller considered to be a robust control strategy is designed and developed for IM drive. A procedure of finding gain and bandwidth of the controller is developed to take care of model inaccuracies, load disturbances and rotor resistance variation. During practical implementation of this controller for IM leads to oscillations and of state variable chattering due to presence of limiter and PWM inverter in the system. Iterative Learning controller (ILC) introduced in recent time is gaining popularity due to capability to take care of short comings of Sliding Mode controller. Feedback and feed forward Iterative Learning controller combining fuzzy logic is designed and developed. The MATLAB/SIMULINK model of IM drive with controllers designed are simulated under various possible operating conditions. A comparative study of three controllers is carried out in similar situation and the response of the drive system is presented.Normally we neglect stability aspect of IM while investigating procedure for performance improvement of IM drive. Stability study of IM in open loop and closed vii loop conditions using Lyapunov criteria and also considering the power balance equation are presented

A Novel Real-time Approach to Unified Power Flow Controller Validation

This paper presents the development of a real-time hardware/software laboratory to interface a soft real-time power system simulator with multiple unified power flow controllers (UPFC) via hardware-in-the-loop (HIL) to study their dynamic responses and validate control and placement approaches. This paper describes a unique laboratory facility that enables large-scale, soft real-time power system simulation coupled with the true physical behavior of a UPFC as opposed to the controller response captured by many other real-time simulators. The HIL line includes a synchronous machine, a UPFC, and a programmable load to reproduce the physical dynamics of the UPFC sub-network