Geometric Algebra in Nonsinusoidal Power Systems: A Case of Study for Passive Compensation

New-generation power networks, such as microgrids, are being affected by the proliferation of nonlinear electronic systems, resulting in harmonic disturbances both in voltage and current that affect the symmetry of the system. This paper presents a method based on the application of geometric algebra (GA) to the resolution of power flow in nonsinusoidal single-phase electrical systems for the correct determination of its components to achieve passive compensation of true quadrature current. It is demonstrated that traditional techniques based on the concepts of Budeanu, Fryze or IEEE1459 fail to determine the interaction between voltage and current and therefore, are not suitable for being used as a basis for the compensation of nonactive power components. An example is included that demonstrates the superiority of GA method and is compared to previous work where GA approaches and traditional methods have also been used

Evolutionary Algorithms for Community Detection in Continental-Scale High-Voltage Transmission Grids

Symmetry is a key concept in the study of power systems, not only because the admittance and Jacobian matrices used in power flow analysis are symmetrical, but because some previous studies have shown that in some real-world power grids there are complex symmetries. In order to investigate the topological characteristics of power grids, this paper proposes the use of evolutionary algorithms for community detection using modularity density measures on networks representing supergrids in order to discover densely connected structures. Two evolutionary approaches (generational genetic algorithm, GGA+, and modularity and improved genetic algorithm, MIGA) were applied. The results obtained in two large networks representing supergrids (European grid and North American grid) provide insights on both the structure of the supergrid and the topological differences between different regions. Numerical and graphical results show how these evolutionary approaches clearly outperform to the well-known Louvain modularity method. In particular, the average value of modularity obtained by GGA+ in the European grid was 0.815, while an average of 0.827 was reached in the North American grid. These results outperform those obtained by MIGA and Louvain methods (0.801 and 0.766 in the European grid and 0.813 and 0.798 in the North American grid, respectively)

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

Detection of Communities within the Multibody System Dynamics Network and Analysis of Their Relations

Multibody system dynamics is already a well developed branch of theoretical, computational and applied mechanics. Thousands of documents can be found in any of the well-known scientific databases. In this work it is demonstrated that multibody system dynamics is built of many thematic communities. Using the Elsevier’s abstract and citation database SCOPUS, a massive amount of data is collected and analyzed with the use of the open source visualization tool Gephi. The information is represented as a large set of nodes with connections to study their graphical distribution and explore geometry and symmetries. A randomized radial symmetry is found in the graphical representation of the collected information. Furthermore, the concept of modularity is used to demonstrate that community structures are present in the field of multibody system dynamics. In particular, twenty-four different thematic communities have been identified. The scientific production of each community is analyzed, which allows to predict its growing rate in the next years. The journals and conference proceedings mainly used by the authors belonging to the community as well as the cooperation between them by country are also analyzed

Active and reactive power conditioning using SMES devices with PMW-CSC: A feedback nonlinear control approach

The active and reactive power conditioning using superconducting magnetic energy storage (SMES) systems for low-voltage distribution networks via feedback nonlinear control is proposed in this paper. The SMES system is interconnected to ac grid using a pulsed-width modulated current source converter (PWM-CSC). The dynamical model of the system exhibits a nonlinear structure, which is eliminated by the application of a nonlinear feedback controller based of the expected behavior of the closed-loop system. The steady state analysis under time-domain reference frame to verify the stability properties on the proposed controller is used. The general control rules allow improving different objectives. The robustness and applicability of the proposed controller is tested considering unbalance and harmonic distortion in the voltage provided by the ac grid. It is also considered the possibility to use the SMES system with the proposed controller to compensate the active power oscillations of a wind-generator system. © 2019 The AuthorsDepartamento Administrativo de Ciencia, Tecnología e Innovación, COLCIENCIAS, Department of Science, Information Technology and Innovation, Queensland Governmen

Nonlinear analysis and control of a reaction wheel pendulum: Lyapunov-based approach

This paper presents a nonlinear analysis, control, and comparison of controllers based on the dynamical model of the reaction wheel pendulum (RWP) in a tutorial style. Classical methodologies such as proportional integral derivative (PID) control and state variables feedback control are explored. Lyapunov's method is proposed to analyze the stability of the proposed nonlinear controllers, and it is also used to design control laws guaranteeing globally asymptotically stability conditions in closed-loop. A swing up strategy is also included to bring the pendulum bar to the desired operating zone at the vertical upper position from an arbitrary initial location. Simulation results show that it is possible to obtain the same dynamical behavior of the RWP system adjusting the control gains adequately. All simulations were conducted via MATLAB Ordinary Differential Equation packages. © 2019 Karabuk Universit

Active and reactive power conditioning using SMES devices with PMW-CSC: A feedback nonlinear control approach

The active and reactive power conditioning using superconducting magnetic energy storage (SMES) systems for low-voltage distribution networks via feedback nonlinear control is proposed in this paper. The SMES system is interconnected to ac grid using a pulsed-width modulated current source converter (PWM-CSC). The dynamical model of the system exhibits a nonlinear structure, which is eliminated by the application of a nonlinear feedback controller based of the expected behavior of the closed-loop system. The steady state analysis under time-domain reference frame to verify the stability properties on the proposed controller is used. The general control rules allow improving different objectives. The robustness and applicability of the proposed controller is tested considering unbalance and harmonic distortion in the voltage provided by the ac grid. It is also considered the possibility to use the SMES system with the proposed controller to compensate the active power oscillations of a wind-generator system. © 2019 The AuthorsDepartamento Administrativo de Ciencia, Tecnología e Innovación, COLCIENCIAS Department of Science, Information Technology and Innovation, Queensland GovernmentThis work was partially supported by the National Scholarship Program Doctorates of the Administrative Department of Science, Technology and Innovation of Colombia ( COLCIENCIAS ), by calling contest 727-2015

Stationary-state analysis of low-voltage DC grids

The optimal power flow is a classic method for alternating current networks, which can also be applied to direct current networks. However, it is needed to design new methods that guarantee convergence and global optimum. Several approximations based on Taylor series expansion linearization, recursive approximations, and convex optimization can be developed. In this chapter, we theoretically and numerically analyze approximations such as successive linear approximations, Newton-Raphson approximation, hyperbolic approximation, semidefinite programming, and second-order cone optimization for solving optimal power flow problems in direct current networks. The emphasis of the chapter is on low-voltage direct current grids (i.e., DC microgrids and DC distribution), but the ideas can be easily extended to high-power applications