scholarly journals A Comparison Between Robust Control Design LMIs for Grid-Connected Converters

2021 ◽  
Author(s):  
GUSTAVO GUILHERME KOCH ◽  
CAIO RUVIARO DANTAS OSóRIO ◽  
VINICIUS FOLETTO MONTAGNER
Keyword(s):  
Superior Performance ◽  
Linear Matrix ◽  
Feedback Controllers ◽  
Quadratic Stability ◽  
Slack Variables ◽  
Grid Impedance ◽  
Point Of Common Coupling ◽  
Common Coupling ◽  
Robust Control Design ◽  
Grid Connected Converters

This paper is focused on a comparison between two linear matrix inequality conditions for design of robust state feedback controllers applied for current regulation of gridconnected converters with LCL filters, operating under uncertain grid impedance at the point of common coupling. The first condition is the well known quadratic stability and the second one is the polyquadratic stability, which uses extra matrix variables. It is shown that the condition with slack variables can provide superior performance in terms of ensuring stable and suitable operation for a larger set of uncertainties.

scholarly journals Robust Quadratic Stabilizability and H∞ Control of Uncertain Linear Discrete-Time Stochastic Systems with State Delay

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Xiushan Jiang ◽  
Xuemin Tian ◽  
Weihai Zhang
Keyword(s):  
Discrete Time ◽  
Stochastic Systems ◽  
Linear Matrix ◽  
Sufficient Condition ◽  
Feedback Controllers ◽  
State Delay ◽  
Quadratic Stability ◽  
Stability And Stabilization ◽  
The Stability ◽  
Theoretical Results

This paper mainly discusses the robust quadratic stability and stabilization of linear discrete-time stochastic systems with state delay and uncertain parameters. By means of the linear matrix inequality (LMI) method, a sufficient condition is, respectively, obtained for the stability and stabilizability of the considered system. Moreover, we design the robust H∞ state feedback controllers such that the system with admissible uncertainties is not only quadratically internally stable but also robust H∞ controllable. A sufficient condition for the existence of the desired robust H∞ controller is obtained. Finally, an example with simulations is given to verify the effectiveness of our theoretical results.

scholarly journals Active Power Transfer Enhancement in VSC using Impedance Compensated DSRF-PLL during Weak Grid Condition

2019 ◽  
Vol 8 (4) ◽  
pp. 2693-2966
Keyword(s):  
Active Power ◽  
Stable Operation ◽  
Phase Detection ◽  
Power Transfer ◽  
Renewable Sources ◽  
Weak Grid ◽  
Synchronous Reference Frame ◽  
Grid Impedance ◽  
Point Of Common Coupling ◽  
Common Coupling

In last two decades the use of renewable sources has been increased tremendously. This has increased the number of inverters connected to grid for the integration of energy from renewable sources. The stability of grid tied inverter is very much important with increased number of inverters. Especially in weak grid, which leads to voltage fluctuation, stability of inverter needs more attention. For a stable operation of VSC it is very important to detect the phase of grid voltage at point of common coupling (PCC) with proper accuracy. In this paper a Double Synchronous Reference Frame PLL (DSRF-PLL) with grid impedance compensation is presented. It is shown that with grid impedance compensation in phase detection, a VSC can be virtually synchronized at a stronger point of common coupling (PCC) in grid and this will enhance the active power transfer capacity of VSC with stable operation in weak grid condition. MATLAB simulation results are presented to verify the findings.

scholarly journals Measurement-Based Distribution Grid Harmonic Impedance Models and Their Uncertainties

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4259
Author(s):  
Ravi Shankar Singh ◽  
Vladimir Ćuk ◽  
Sjef Cobben
Keyword(s):  
Estimation Method ◽  
Distribution Grid ◽  
Harmonic Model ◽  
Equivalent Models ◽  
Grid Impedance ◽  
Before And After ◽  
Point Of Common Coupling ◽  
Simulated Network ◽  
Common Coupling ◽  
Impedance Models

Aggregated Norton’s equivalent models, with parallel impedance and current injection at different harmonic frequencies are used to model the distribution grid in harmonic studies. These models are derived based on measurements and/or prior knowledge about the grid. The measurement-based distribution (sub-)grid impedance estimation method uses harmonic phasors of 3-phase current and voltage measurements to capture the response of the distribution (sub-)grid before and after an event in the utility side of the grid. However, due to increasing non-linear components in the grid, knowledge about uncertainty in parameters of such equivalent models which intrinsically describe a linear grid becomes important. The aim of this paper is to present two novel methods to calculate the uncertainty of the measurement-based Norton’s equivalent harmonic model of the distribution (sub-)grids as seen from the utility side at the Point of Common Coupling (PCC). The impedance and the uncertainty calculations are demonstrated on a simulated network.

The robustness assessment of doubly fed induction generator-wind turbine during short circuit

2019 ◽  
Vol 31 (4) ◽  
pp. 570-582 ◽  
Author(s):  
Muhammad Shahzad Nazir ◽  
Ahmed N Abdalla
Keyword(s):  
Short Circuit ◽  
Wind Farms ◽  
Superior Performance ◽  
Induction Generator ◽  
Doubly Fed Induction Generator ◽  
Point Of Common Coupling ◽  
Common Coupling ◽  
Doubly Fed ◽  
Grid Side ◽  
Grid Side Converter

Energy sources, such as wind, solar, hydro, etc., are an important source of energy, and wind power generators are important energy conversion machines. The doubly fed induction generator has wide industrial and commercial applications due to its superior performance, combined with fault and eco-friendly properties. However, the fault current dynamics of wind farms identify the potential impacts of fault currents and the voltage on the protection. This study focuses on wind farms (employing doubly fed induction generators) perturbation during symmetrical (three-phase) symmetrical short circuit (SSC) at different points. The detail of analyzing the doubly fed induction generator (DFIG) performance during transient conditions, control and modeling is studied in this paper. These two points are selected as grid-side converter and point of common coupling, respectively. These comparison results fetched the more precise understanding of the fault diagnosis reliability with reduced complexity, stability, and optimization of the system. The present findings illustrated the main difference between point of common coupling and grid-side converter under SSC faults and the robustness of these two mentioned points.

scholarly journals A Proposed Harmonic Monitoring System for Large Power Users Considering Harmonic Limits

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4507
Author(s):  
Rosalia Sinvula ◽  
Khaled Mohamed Abo-Al-Ez ◽  
Mohamed Tariq Kahn
Keyword(s):  
Monitoring System ◽  
Renewable Energy Sources ◽  
Electronic Devices ◽  
Harmonic Distortion ◽  
Large Power ◽  
High Penetration ◽  
Point Of Common Coupling ◽  
Common Coupling ◽  
Power Utilities ◽  
The Individual

Most power utilities within Southern Africa are faced with the challenges of harmonic distortion due to the high penetration of renewable energy sources (RES) and the use of electronic devices. There is an excessive total harmonic distortion (THD) measured at the point of common coupling (PCC). In this paper, a proposed harmonic monitoring system for large power users (LPUs) is developed. This proposed system considers harmonic limits of the individual and THD of the customers allowed injecting into the network, which should be part of the contractual electricity supply agreement (ESA). Hence, it will enable the monitoring of harmonic distortion to be smooth by determining whether the customer has passed or failed compliance for individual harmonic order and the THD of the voltage. The measurements of harmonic distortion are done using the Unipower power quality (PQ) analyzers that are connected at different points within the industrial network. Measurements of harmonic distortion of an industrial site are compared to the simulation results performed by DIgSILENT software to validate the proposed harmonic monitoring system. Based on the validation results, it is recommended that the ESA between the power utilities and the customers should consist of the harmonic limits.

Assessment of power quality parameters and indicators at the point of common coupling in a low voltage power grid with photovoltaic generation emulated

2022 ◽  
Vol 203 ◽  
pp. 107679
Author(s):  
Oscar Pinzón-Quintero ◽  
Daniel Gaviria-Ospina ◽  
Alejandro Parrado-Duque ◽  
Rusber Rodríguez-Velásquez ◽  
German Osma-Pinto
Keyword(s):  
Power Quality ◽  
Low Voltage ◽  
Power Grid ◽  
Quality Parameters ◽  
Photovoltaic Generation ◽  
Point Of Common Coupling ◽  
Common Coupling

scholarly journals Sensor Fault-Tolerant Control Design for Mini Motion Package Electro-Hydraulic Actuator

Processes ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 89 ◽  
Author(s):  
Tan Van Nguyen ◽  
Cheolkeun Ha
Keyword(s):  
Tracking Control ◽  
Position Control ◽  
Fault Tolerant ◽  
Human Life ◽  
Rapid Development ◽  
Fault Tolerant Control ◽  
Superior Performance ◽  
Linear Matrix ◽  
Sensor Faults ◽  
Sensor Fault

With the rapid development of computer science and information and communication technology (ICT), increasingly intelligent, and complex systems have been applied to industries as well as human life. Fault-tolerant control (FTC) has, therefore, become one of the most important topics attracting attention from both engineers and researchers to maintain system performances when faults occur. The ultimate goal of this study was to develop a sensor fault-tolerant control (SFTC) to enhance the robust position tracking control of a class of electro-hydraulic actuators called mini motion packages (MMPs), which are widely used for applications requiring large force-displacement ratios. First, a mathematical model of the MMP system is presented, which is then applied in the position control process of the MMP system. Here, a well-known proportional, integrated and derivative (PID) control algorithm is employed to ensure the positional response to the reference position. Second, an unknown input observer (UIO) is designed to estimate the state vector and sensor faults using a linear matrix inequality (LMI) optimization algorithm. Then an SFTC is used to deal with sensor faults of the MMP system. The SFTC is formed of the fault detection and the fault compensation with the goal of determining the location, time of occurrence, and magnitude of the faults in the fault signal compensation process. Finally, numerical simulations were run to demonstrate the superior performance of the proposed approach compared to traditional tracking control.

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