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Journal ArticleDOI

Power Quality Enhancement Using Linear Quadratic Regulator Based Current-controlled Voltage Source Inverter for the Grid Integrated Renewable Energy System

TL;DR: An optimal control strategy using linear quadratic regulator applied in current-controlled voltage source inverter (CCVSI) to control the real and reactive power flow between the renewable energy system (RES) and the grid is presented.
Abstract: This paper presents an optimal control strategy using linear quadratic regulator (LQR) applied in current-controlled voltage source inverter (CCVSI) to control the real and reactive power flow betw...
Citations
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Journal ArticleDOI
TL;DR: The SMC using equivalent control function outperforms the other methods in terms of chattering, THD and PF in the grid during balanced and unbalanced grid voltage conditions even in the existence of nonlinear loads.
Abstract: Development of control technologies facilitates the integration of renewable energy sources to the grid through power electronic converters. In this study, the inverter acts as shunt active power filter along with the power conversion operation. Various sliding mode control (SMC) techniques namely relay and signum method, hysteresis method and equivalent control method are implemented to control the real, and reactive power flow between Renewable Energy System (RES), load and grid using an inverter. To reduce the complexity, the control law (u eq) for equivalent control method is derived using a simple single-phase equivalent circuit of a three-phase voltage source inverter. In this study, the robustness is enhanced by choosing the integral sliding surface. These controllers are used to reduce the total harmonic distortion (THD) and to ensure unity power factor (PF) in the grid during balanced and unbalanced grid voltage conditions even in the existence of nonlinear loads. The SMC using equivalent control function outperforms the other methods in terms of chattering, THD and PF. To illustrate the effectiveness, three different modes are considered: (i) no RES power, (ii) insufficient RES power and (iii) excess RES power. The performance of controllers is validated by the simulation and experimental results.

7 citations

Journal ArticleDOI
24 Apr 2020-Symmetry
TL;DR: This article constructed Lyapunov-Krasovskii functionals containing several symmetric positive definite matrices to obtain robust finite-time stability and stabilization of the uncertain linear system with a non-differentiable time-varying delay.
Abstract: Practical systems such as hybrid power systems are currently implemented around the world. In order to get the system to work properly, the systems usually require their behavior to be maintained or state values to stay within a certain threshold. However, it is difficult to form a perfect mathematical model for describing behavior of the practical systems since there may be some information (uncertainties) that is not observed. Thus, in this article, we studied the stability of an uncertain linear system with a non-differentiable time-varying delay. We constructed Lyapunov-Krasovskii functionals (LKFs) containing several symmetric positive definite matrices to obtain robust finite-time stability (RFTS) and stabilization (RFTU) of the uncertain linear system. With the controller and uncertainties in the considered system, there exist nonlinear terms occurring in the formulation process. Past research handled these nonlinear terms as new variables but this led to some difficulty from a computation point of view. Instead, we applied a novel approach via Cauchy-like matrix inequalities to handle these difficulties. In the end, we present three numerical simulations to show the effectiveness of our proposed theory.

7 citations

Journal ArticleDOI
TL;DR: This paper presents a control to mitigate these power quality issues in addition to the control of power flow between solar photovoltaic system and non-linear load, using linear quadratic regulator.

4 citations

References
More filters
Journal ArticleDOI
TL;DR: The novelty of the proposed system lies in extension of the generic DPC-SVM scheme by additional higher harmonic and voltage dips compensation modules and implementation of the whole algorithm in a single chip floating point microcontroller.
Abstract: Power electronic Grid-Connected Converters (GCCs) are widely applied as grid interface in renewable energy sources. This paper proposes an extended Direct Power Control with Space Vector Modulation (DPC-SVM) scheme with improved operation performance under grid distortions. The real-time operated DPC-SVM scheme has to execute several important tasks as: space vector pulse width modulation, active and reactive power feedback control, grid current harmonics and voltage dips compensation. Thus, development and implementation of the DPC-SVM algorithm using single chip floating-point microcontroller TMS320F28335 is described. It combines large peripheral equipment, typical for microcontrollers, with high computation capacity characteristic for Digital Signal Processors (DSPs). The novelty of the proposed system lies in extension of the generic DPC-SVM scheme by additional higher harmonic and voltage dips compensation modules and implementation of the whole algorithm in a single chip floating point microcontroller. Overview of the laboratory setup, description of basic algorithm subtasks sequence, software optimization as well as execution time of specific program modules on fixed-point and floating-point processors are discussed. Selected oscillograms illustrating operation and robustness of the developed algorithm used in 5 kVA laboratory model of the GCC are presented.

193 citations

Proceedings ArticleDOI
06 Nov 2009
TL;DR: In this article, a suitable pole placement strategy is proposed, that ensures fulfilling the requirements, which are commonly specified with respect to rise time, overshoot, and proper resonance damping.
Abstract: Design and analysis of PI state space control for grid-connected PWM converters with LCL filters based on pole placement approach is addressed. State space control offers almost full controllability of system dynamic. However, pole placement design is difficult and usually requires much experience. In this paper a suitable pole placement strategy is proposed, that ensures fulfilling the requirements, which are commonly specified with respect to rise time, overshoot, and proper resonance damping. Controller parameter expressions are derived in terms of system parameters and specified poles and zeros. Hence straightforward controller tuning for a particular system setting is possible. Performance is analyzed by means of transfer function-based calculations, simulations with Matlab, and experimental tests.

193 citations

Journal ArticleDOI
TL;DR: In this article, the dynamic performance of the Static Synchronous Compensator (STATCOM) and the SSSC was investigated theoretically and by exact digital simulation. And the proposed control schemes were validated by digital simulations.
Abstract: The paper presents an in-depth investigation of the dynamic performance of the Static Synchronous Compensator (STATCOM) and the Static Synchronous Series Compensator (SSSC) theoretically and by exact digital simulation. A 24-pulse GTO dc-ac converter model is designed to represent the operation of the STATCOM and SSSC within a power transmission system. Two major factors of the STATCOM instability are analyzed and a new Automatic Gain Controller (AGC) is proposed to ensure the stable operation of the STATCOM under various load conditions. It is shown that the Phase-Locked Loop (PLL) inherent delay has a great effect on the dynamic operation of the SSSC and a new auxiliary regulator is proposed to enhance the dynamic performance of the SSSC. The proposed control schemes are validated by digital simulation.

174 citations


"Power Quality Enhancement Using Lin..." refers background in this paper

  • ...Active power filters are usually used to compensate the load reactive power, thus mitigating the power quality issues [4]–[8]....

    [...]

01 Jan 2017
TL;DR: In this paper, the authors present a line-to-neutral diagram of a single-phase transformer and a three-phase generator in the context of power system analysis, and compare the three line models.
Abstract: Preface 1 Introduction to Power System Analysis 11 Introduction 12 Scope of the Material 13 General Characteristics of Power Systems 14 Phasors 15 Equivalent Line-To-Neutral Diagrams 16 Power in Single-phase Circuits 17 Power in Three-phase Circuits 18 Per Unit Normalization 19 Power System Structure 2 The Generation of Electric Energy 21 Introduction 22 Thermal Power Plants 23 Nuclear Power Plants 24 Renewable Energy 25 The Synchronous Machine 3 The Transmission of Electric Energy 31 Introduction 32 Transmission and Distribution Network 33 Network Structures 34 Substations 35 Substation Concepts 36 Protection of Transmission And Distribution Networks 37 Transformers 38 Power Carriers 4 The Utilization of Electric Energy 41 Introduction 42 Types of Load 43 Classification of Grid Users 5 Power System Control 51 Introduction 52 Basics of Power System Control 53 Active Power and Frequency Control 54 Voltage Control and Reactive Power 55 Control of Transported Power 56 Flexible AC Transmission Systems (FACTS) 6 Energy Management Systems 61 Introduction 62 Loadflow or Power Flow Computation 63 Optimal Powerflow 64 State Estimator 7 Electricity Markets 71 Introduction 72 Electricity Market Structure 73 Market Clearing 74 Social Welfare 75 Market Coupling 8 Future Power Systems 81 Introduction 82 Renewable Energy 83 Decentralized Or Distributed Generation 84 Power-electronic Interfaces 85 Energy Storage 86 Blackouts and Chaotic Phenomena Appendices A Maxwell's Laws A1 Introduction A2 Power Series Approach To Time-varying Fields A3 Quasi-Static Field Of A Parallel-plate Capacitor A4 Quasi-Static Field Of A Single-turn Inductor A5 Quasi-Static Field Of A Resistor A6 Circuit Modeling B Power Transformer Model B1 Introduction B2 The Ideal Transformer B3 Magnetically-Coupled Coils B4 The Non-ideal Transformer B5 Three-phase Transformer C Synchronous Machine Model C1 Introduction C2 The Primitive Synchronous Machine C3 The Single-phase Synchronous Machine C4 The Three-phase Synchronous Machine C5 Synchronous Generator In The Power System D Induction Machine Model D1 Introduction D2 The Basic Principle of The Induction Machine D3 The Magnetic Field In The Air-Gap D4 A Simple Circuit Model For The Induction Machine D5 Induction Motor In The Power System E The Representation of Lines And Cables E1 Introduction E2 The Long Transmission Line E3 The Medium-length Transmission Line E4 The Short Transmission Line E5 Comparison of The Three Line Models E6 The Underground Cable References List of Abbreviations List of Symbols Index

152 citations


"Power Quality Enhancement Using Lin..." refers background in this paper

  • ...The usage of power electronic equipment and non-linear loads deteriorate the power quality of power system [3]....

    [...]

Journal ArticleDOI
TL;DR: In this article, instantaneous active and reactive power (p-q) and current (Id-Iq) control strategies for extracting the three-phase reference currents for shunt active power filters are compared, evaluating their performance under different source voltage conditions with PI and fuzzy logic controllers in MATLAB/Simulink environment and also implemented using Real-Time Digital Simulator Hardware (RTDS Hardware).

120 citations