Root-locus method for the stability analysis of high-order FDTD

2018 ◽  
Author(s):  
Ammar Guellab ◽  
Qun Wu
Keyword(s):  
Stability Analysis ◽  
High Order ◽  
Root Locus ◽  
Locus Method ◽  
The Stability

scholarly journals The Interaction Stability Analysis of a Multi-Inverter System Containing Different Types of Inverters

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2244 ◽  
Author(s):  
Chen Zheng ◽  
Qionglin Li ◽  
Lin Zhou ◽  
Bin Li ◽  
Mingxuan Mao
Keyword(s):  
Stability Analysis ◽  
Power Grid ◽  
Root Locus ◽  
Criterion A ◽  
Locus Method ◽  
Different Types ◽  
Simulation And Experiment ◽  
The Stability ◽  
Harmonic Resonance ◽  
Universal Interaction

The existing stability investigations of the system containing different types of inverters are insufficient. The paper aims to reveal the more universal interaction stability mechanism of the system containing different types of inverters. Firstly, the multi-inverter system is decomposed into an admittance network (AN) and excitation sources. Then, the interaction between two different inverters, as well as the interaction between the inverter and the power grid, are analyzed by the root locus method. This reveals that the stability of the interaction between the inverter and the power grid is exclusively determined by AN. However, the stability of the interaction between different inverters not only depends on AN but also relies on whether the two inverters have common right-half plane (RHP) poles. To make the multi-inverter system stable, the following two criteria must be satisfied: (a) AN is stable and (b) any two different inverters do not have the same RHP poles. If criterion (a) is not satisfied, the harmonic resonance will arise in all currents. Resonant harmonics will only circulate among partial inverters and will not inject into the power grid if criterion (a) is satisfied but criterion (b) is not satisfied. Theoretical analysis is validated by simulation and experiment results.

Stability analysis and control in the process of floating-target capture with hardware-in-the-loop system

2017 ◽  
Vol 44 (1) ◽  
pp. 49-57
Author(s):  
Zongwu Xie ◽  
Xiaoyu Zhao ◽  
Yu Zhang ◽  
Qi Zhang ◽  
Haitao Yang ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Industrial Robot ◽  
System Stability ◽  
Hardware In The Loop ◽  
Root Locus ◽  
Content Type ◽  
Target Capture ◽  
Locus Method ◽  
The Status ◽  
The Stability

Purpose The purpose of this paper is to develop an easily implemented and practical stabilizing strategy for the hardware-in-the-loop (HIL) system. As the status of HIL system in the ground verification experiment for space equipment keeps rising, the stability problems introduced by high stiffness of industrial robot and discretization of the system need to be solved ungently. Thus, the study of the system stability is essential and significant. Design/methodology/approach To study the system stability, a mathematical model is built on the basis of control circle. And root-locus and 3D root-locus method are applied to the model to figure out the relationship between system stability and system parameters. Findings The mathematical model works well in describing the HIL system in the process of capturing free-floating targets, and the stabilizing strategy can be adopted to improve the system dynamic characteristic which meets the needs of the practical application. Originality/value A method named 3D root-locus is extended from traditional root-locus method. And the improved method graphically displays the stability of the system under the influence of multivariable. And the strategy that stabilize the system with elastic component has a strong feasible and promotional value.

scholarly journals A Gallery of Root Locus of Fractional Systems

2013 ◽  
Author(s):  
J. A. Tenreiro Machado
Keyword(s):  
Stability Analysis ◽  
Transfer Functions ◽  
Numerical Procedure ◽  
Root Locus ◽  
Closed Loop System ◽  
Fractional Systems ◽  
Finite Precision ◽  
Know How ◽  
The Stability ◽  
Fractional Orders

The root locus (RL) is a classical tool for the stability analysis of integer order linear systems, but its application in the fractional counterpart poses some difficulties. Therefore, researchers have mainly preferred to adopt frequency based methods. Nevertheless, recently the RL was considered for the stability analysis of fractional systems. One first method is by tacking advantage of commensurable expressions that occur when truncating fractional orders up to a finite precision. The second method consists of searching the complex plane for solutions of the characteristic equation using a numerical procedure. The resulting charts are insightful about the characteristics of the closed-loop system that outperform the frequency response methods. Given the limited know how in this particular topic and the shortage of literature, this study explores several types of fractional-order transfer functions and presents the corresponding RL.

Root-locus approach to the stability analysis of interval matrices

1987 ◽  
Vol 46 (3) ◽  
pp. 817-822 ◽  
Author(s):  
YAU-TARNG JUANG ◽  
TE-SON KUO ◽  
CHEN-FA HSU ◽  
SHENG-DE WANG
Keyword(s):  
Stability Analysis ◽  
Root Locus ◽  
Interval Matrices ◽  
The Stability

On the Use of High-Order Accurate Solutions of PNS Schemes as Basic Flows for Stability Analysis of Hypersonic Axisymmetric Flows

2007 ◽  
Vol 129 (10) ◽  
pp. 1328-1338 ◽  
Author(s):  
Kazem Hejranfar ◽  
Vahid Esfahanian ◽  
Hossein Mahmoodi Darian
Keyword(s):  
Stability Analysis ◽  
Fourth Order ◽  
High Order ◽  
Basic Flow ◽  
Navier Stokes ◽  
Numerical Dissipation ◽  
Flow Models ◽  
Transition Prediction ◽  
The Stability ◽  
Stability Results

High-order accurate solutions of parabolized Navier–Stokes (PNS) schemes are used as basic flow models for stability analysis of hypersonic axisymmetric flows over blunt and sharp cones at Mach 8. Both the PNS and the globally iterated PNS (IPNS) schemes are utilized. The IPNS scheme can provide the basic flow field and stability results comparable with those of the thin-layer Navier–Stokes (TLNS) scheme. As a result, using the fourth-order compact IPNS scheme, a high-order accurate basic flow model suitable for stability analysis and transition prediction can be efficiently provided. The numerical solution of the PNS equations is based on an implicit algorithm with a shock fitting procedure in which the basic flow variables and their first and second derivatives required for the stability calculations are automatically obtained with the fourth-order accuracy. In addition, consistent with the solution of the basic flow, a fourth-order compact finite-difference scheme, which does not need higher derivatives of the basic flow, is efficiently implemented to solve the parallel-flow linear stability equations in intrinsic orthogonal coordinates. A sensitivity analysis is also conducted to evaluate the effects of numerical dissipation and grid size and also accuracy of computing the basic flow derivatives on the stability results. The present results demonstrate the efficiency and accuracy of using high-order compact solutions of the PNS schemes as basic flow models for stability and transition prediction in hypersonic flows. Moreover, indications are that high-order compact methods used for basic-flow computations are sensitive to the grid size and especially the numerical dissipation terms, and therefore, more careful attention must be kept to obtain an accurate solution of the stability and transition results.

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