scholarly journals Mathematical Model and Stability Analysis of Inverter-Based Distributed Generator

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Alireza Khadem Abbasi ◽  
Mohd Wazir Mustafa
Keyword(s):  
Stability Analysis ◽  
Signal Model ◽  
Proper Selection ◽  
Distributed Generator ◽  
Small Signal Model ◽  
Proposed Model ◽  
The Stability ◽  
Frequency Variations ◽  
Selection Of ◽  
Prime Source

This paper presents a mathematical (small-signal) model of an electronically interfaced distributed generator (DG) by considering the effect of voltage and frequency variations of the prime source. Dynamic equations are found by linearization about an operating point. In this study, the dynamic of DC part of the interface is included in the model. The stability analysis shows with proper selection of system parameters; the system is stable during steady-state and dynamic situations, and oscillatory modes are well damped. The proposed model is useful to study stability analysis of a standalone DG or a Microgrid.

Divided DQ Small-Signal Model: A New Perspective for the Stability Analysis of Three-Phase Grid-Tied Inverters

2019 ◽  
Vol 66 (8) ◽  
pp. 6493-6504 ◽  
Author(s):  
Zhikang Shuai ◽  
Yang Li ◽  
Weimin Wu ◽  
Chunming Tu ◽  
An Luo ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Small Signal ◽  
Signal Model ◽  
Small Signal Model ◽  
Three Phase ◽  
New Perspective ◽  
The Stability

scholarly journals Limitations of Small-Signal Modeling of Grid-Connected VSCs under Phase Jumps and Frequency Deviations

2020 ◽  
Author(s):  
Hongyang Zhang ◽  
xiongfei wang ◽  
östlund stefan
Keyword(s):  
Voltage Source ◽  
Frequency Variation ◽  
Small Signal ◽  
Voltage Source Converters ◽  
Signal Model ◽  
Small Signal Model ◽  
Frame Transformation ◽  
The Stability ◽  
Small Signal Modeling ◽  
Frequency Variations

The stability of grid-connected voltage source converters (VSCs) is commonly studied by the small-signal model in the synchronous reference (dq) frame. With phase-locked loop dynamic from VSCs, it is inevitable to convert the small-signal model to a common dq frame. When linearizing the frame transformation, the trigonometric functions of the angle are approximated by first-order terms. In this letter, the limitation of such linearization on the dq-transformation is discussed. The accuracy of the model, in presence of phase jumps and frequency variations, are examined. It is found that even under small phase jumps, mismatches are found between the small-signal model (SSM) and a nonlinear model (NM). It is further revealed that during the dynamics of frequency variation, significant mismatches can occur between the SSM and the NM.

scholarly journals Limitations of Small-Signal Modeling of Grid-Connected VSCs under Phase Jumps and Frequency Deviations

2020 ◽  
Author(s):  
Hongyang Zhang ◽  
xiongfei wang ◽  
östlund stefan
Keyword(s):  
Voltage Source ◽  
Frequency Variation ◽  
Small Signal ◽  
Voltage Source Converters ◽  
Signal Model ◽  
Small Signal Model ◽  
Frame Transformation ◽  
The Stability ◽  
Small Signal Modeling ◽  
Frequency Variations

The stability of grid-connected voltage source converters (VSCs) is commonly studied by the small-signal model in the synchronous reference (dq) frame. With phase-locked loop dynamic from VSCs, it is inevitable to convert the small-signal model to a common dq frame. When linearizing the frame transformation, the trigonometric functions of the angle are approximated by first-order terms. In this letter, the limitation of such linearization on the dq-transformation is discussed. The accuracy of the model, in presence of phase jumps and frequency variations, are examined. It is found that even under small phase jumps, mismatches are found between the small-signal model (SSM) and a nonlinear model (NM). It is further revealed that during the dynamics of frequency variation, significant mismatches can occur between the SSM and the NM.

scholarly journals Impedance Modeling and Stability Analysis for Cascade System of Three-Phase PWM Rectifier and LLC Resonant Converter

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3050 ◽  
Author(s):  
Rutian Wang ◽  
Yuyang Wu ◽  
Guoqing He ◽  
Ying Lv ◽  
Jiaxing Du ◽  
...  
Keyword(s):  
Resonant Converter ◽  
Pwm Rectifier ◽  
Output Impedance ◽  
Cascade System ◽  
Signal Model ◽  
Impedance Model ◽  
Small Signal Model ◽  
Three Phase ◽  
Llc Resonant Converter ◽  
The Stability

In this paper; the impedance model of PWM rectifier and LLC resonant converter are deduced, and the stability analysis of cascade system is studied. The principle of three-phase PWM rectifier is introduced; and the small signal model in d-q coordinate system is deduced. The expression of dc side output impedance model for PWM rectifier is derived. The LLC resonant converter is operated in a fixed-frequency state, and the LLC resonant converter is modeled as a small signal model. On this basis, the input impedance model expression of the LLC resonant converter is derived. According to the impedance stability criterion, it can seen that the amplitude of input impedance is greater than the amplitude of output impedance in a certain frequency domain. In addition, the Nyquist curve is not around the point (−1,0), which can judge that the cascade system is stable. In simulation software, a cascade system simulation is built and corresponding simulation curves are obtained, which verifies the stability of the cascade system.

Small-Signal Modeling of the LLC Half-Bridge Resonant Converter

2019 ◽  
Vol 28 (04) ◽  
pp. 1950063
Author(s):  
Jianguang Ma ◽  
Xueye Wei ◽  
Liang Hu ◽  
Junhong Zhang
Keyword(s):  
High Power ◽  
Experimental Result ◽  
Order System ◽  
Small Signal ◽  
Resonant Converter ◽  
Signal Modeling ◽  
Signal Model ◽  
Small Signal Model ◽  
Proposed Model ◽  
Small Signal Modeling

This paper proposes a small-signal modeling method for building an LLC half-bridge resonant converter. In recent years, the LLC half-bridge resonant converter has attracted the attention of many researchers because of its high-power conversion efficiency and high-power density. Generally, the LLC half-bridge resonant converter consists of many passive components, including stray and parasitic elements, resulting in a high-order system. Because the fundamental harmonic approximation (FHA) method for an LLC resonant converter only considers the fundamental harmonic and neglects higher harmonics, it is not accurate and introduces large errors in a higher-order system. In this paper, according to the operation principle of the LLC half-bridge resonant converter, a small-signal model is established. Based on the small-signal model, the input-to-output and control-to-output transfer function is derived. The experimental result verified that the proposed model yields a high accuracy, thereby highlighting the usefulness and versatility of the proposed model over other existing models.

Conformity and stability analysis of a modified spring–mass–damper system dynamics-based car-following model

2019 ◽  
Vol 33 (06) ◽  
pp. 1950025 ◽  
Author(s):  
Caleb Ronald Munigety
Keyword(s):  
Stability Analysis ◽  
System Dynamics ◽  
Traffic System ◽  
Car Following ◽  
Proposed Model ◽  
Mass Damper ◽  
Traffic Stream ◽  
Behavioral Parameters ◽  
Car Following Model ◽  
The Stability

Modeling the dynamics of a traffic system involves using the principles of both physical and social sciences since it is composed of vehicles as well as drivers. A novel car-following model is proposed in this paper by incorporating the socio-psychological aspects of drivers into the dynamics of a purely physics-based spring–mass–damper mechanical system to represent the driver–vehicle longitudinal movements in a traffic stream. The crux of this model is that a traffic system can be viewed as various masses interacting with each other by means of springs and dampers attached between them. While the spring and damping constants represent the driver behavioral parameters, the mass component represents the vehicle characteristics. The proposed model when tested for its ability to capture the traffic system dynamics both at micro, driver, and macro, stream, levels behaved pragmatically. The stability analysis carried out using perturbation method also revealed that the proposed model is both locally and asymptotically stable.

scholarly journals Small-Signal Modeling of PMSG-Based Wind Turbine for Low Voltage Ride-Through and Artificial Intelligent Studies

Energies ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 6685
Author(s):  
Mojtaba Nasiri ◽  
Saleh Mobayen ◽  
Behdad Faridpak ◽  
Afef Fekih ◽  
Arthur Chang
Keyword(s):  
Wind Turbine ◽  
Low Voltage ◽  
Voltage Drop ◽  
Small Signal ◽  
Signal Model ◽  
Artificial Intelligent ◽  
Low Voltage Ride Through ◽  
Small Signal Model ◽  
Proposed Model ◽  
Intelligent Methods

In recent years, due to the several advantages of permanent magnet synchronous generator (PMSG), the number of wind farms utilizing this technology has been significantly grown. The determination of the failure mechanism in these devices is the major challenge which has been addressed in many studies. Particularly, response to grid code compliance by wind power in the voltage drop situation needs to be comprehensively analyzed. In this paper, a small signal model of a PMSG-based wind turbine for low voltage ride-through (LVRT) and suitable for stability and artificial intelligent studies is presented. Accordingly, the generator side converter controls the dc-link voltage, and the maximum power point tracking is performed by the grid side converter. Given the proposed model, the speed of the simulation for stability analysis studies can be significantly increased by intelligent methods. Furthermore, the simplified approach can be achieved for calculating the optimal coefficients of the proportionality-integral controller by intelligent methods in a short time. By simulating the proposed small-signal model and comparing it with the block-based simulation in MATLAB/SIMULINK software, the appropriate accuracy and efficiency of the proposed model are confirmed.

scholarly journals Stability Analysis of Train Movement with Uncertain Factors

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
JingJing Ye ◽  
KePing Li ◽  
XueDong Jiang
Keyword(s):  
Relaxation Time ◽  
Stability Analysis ◽  
Fuzzy Theory ◽  
Traffic Model ◽  
Optimal Velocity ◽  
Car Following ◽  
Proposed Model ◽  
Car Following Model ◽  
Simulation Results ◽  
The Stability

We propose a new traffic model which is based on the traditional OV (optimal velocity) car-following model. Here, some realistic factors are regarded as uncertain quantity, such as the headway distance. Our aim is to analyze and discuss the stability of car-following model under the constraint of uncertain factors. Then, according to the principle of expected value in fuzzy theory, an improved OV traffic model is constructed. Simulation results show that our proposed model can avoid collisions effectively under uncertain environment, and its stability can also be improved. Moreover, we discuss its stability as some parameters change, such as the relaxation time.

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