A Hybrid Damping Method for LCL-Filter Based Grid-Tied Inverter

2015 ◽  
Vol 734 ◽  
pp. 805-810
Author(s):  
Lan Ma ◽  
Hong Bing Xu ◽  
Jian Xiao Zou ◽  
Meng Shu Li ◽  
Tao Han
Keyword(s):  
System Stability ◽  
Long Distance ◽  
Lcl Filter ◽  
Control Loops ◽  
Grid Impedance ◽  
Grid Side ◽  
Strategy Design ◽  
And Control ◽  
Hybrid Damping

With more and more distributed renewable energy connecting to the power system, inverters are widely used as the power electronic interface. However, high-order filters will inevitably bring in problems of resonance. Additionally, long-distance transmission and quantities of inverters increase the grid impedance obviously. Wide variation of grid impedance will not only impact on the resonance of filters, but also challenge stability of inverters system. This paper investigates how resonance and stability of grid-tied inverter with LCL-filter will be affected by the grid impedance. And a hybrid damping method based on RC parallel damper and biquad digital filter is proposed, this method presents relatively low power losses, requires no extra sensors and control loops with its simple damping strategy design. Moreover, it apparently improves system stability and waveform quality of grid-side current when grid impedance varies in a comparatively large range. Both validity and feasibility of this algorithm are verified via simulations.

scholarly journals Research on Adaptive Suppression of LCL Converter Resonance Grid-Connected System

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Junwei Li ◽  
Yafang Tang ◽  
Junke Li
Keyword(s):  
Particle Swarm Optimization ◽  
Particle Swarm ◽  
Stability Margin ◽  
System Stability ◽  
Current Feedback ◽  
Swarm Optimization ◽  
Lcl Filter ◽  
Rbf Network ◽  
Grid Impedance ◽  
Suppression Method

LCL-type converters are widely used in grid-connected systems due to their small size and good filtering performance. However, the resonance suppression problem brought by the LCL filter cannot be ignored. The capacitive current feedback is a commonly used resonance suppression method. In applications, the grid impedance can cause LCL filter resonance. Thus, this paper presents an adaptive resonance suppression method based on the RBF network optimized by particle swarm optimization. This method optimizes the initial parameters of the RBF network through particle swarm optimization, identifies the parameters of the PI controller by RBF neural network’s own identification capability, and updates the active damping coefficient based on constraints such as stability margin, thereby realizing the LCL-type inverter to maintain the system stability when the grid impedance changes. The effectiveness of the method is verified by experiments.

scholarly journals Integrated Communication and Control Systems: Part II—Design Considerations

1988 ◽  
Vol 110 (4) ◽  
pp. 374-381 ◽  
Author(s):  
Asok Ray ◽  
Yoram Halevi
Keyword(s):  
Control Systems ◽  
Dynamic Performance ◽  
Sufficient Conditions ◽  
System Stability ◽  
Time Varying ◽  
Control Loops ◽  
Analysis And Design ◽  
Integrated Communication ◽  
And Control ◽  
Analytical Approaches

Asynchronous time-division multiplexed networks, used in Integrated Communication and Control Systems (ICCS), introduce time-varying and possibly stochastic delays in the feedback control loops. The objective of this on-going research is to develop a comprehensive methodology for the analysis and design of the above class of delayed control systems. In the first part [1] of this two-part paper, we developed a discrete-time, finite-dimensional, time-varying model of the delayed control system; necessary and sufficient conditions for system stability have been established for periodically varying delays. This second part elucidates the significance of the above model relative to the system dynamic performance as well as addresses major criteria for and outlines alternative analytical approaches to ICCS design. Pertinent concepts are illustrated by simulation.

scholarly journals A Theoretical Concept of Decoupled Current Control Scheme for Grid-Connected Inverter with L-C-L Filter

2021 ◽  
Vol 11 (14) ◽  
pp. 6256
Author(s):  
Mohamad Amin Ghasemi ◽  
Seyed Fariborz Zarei ◽  
Saeed Peyghami ◽  
Frede Blaabjerg
Keyword(s):  
Control Method ◽  
Controller Design ◽  
Current Control ◽  
System Stability ◽  
State Equations ◽  
Lcl Filter ◽  
Control Scheme ◽  
Grid Connected Inverter ◽  
The Stability ◽  
Grid Side

This paper proposes a nonlinear decoupled current control scheme for a grid-connected inverter with LCL filter. Decoupling the active and reactive current control channels is one of the main demands in the control of inverters. For inverters with an L filter, the decoupling can be achieved by a proper feed-forward of grid voltages. However, the coupling of channels is a complex issue for converters with LCL filters. The resonance mode of the LCL filter may cause instability, which adds more complexity to the analysis. In this paper, state equations of the system are provided, which highlight the coupling between active and reactive currents injected into the grid. Accordingly, a non-linear control scheme is proposed which effectively decouples the channels and dampens the resonant modes of the LCL filter. The stability of the proposed control method is verified by the Lyapunov criterion. Independency of the system stability to the grid-impedance is another feature of the proposed approach. Moreover, only grid-side currents are needed for implementation of the proposed scheme, avoiding the need for additional current sensors for the output capacitor and grid-side inductor. For accurate modelling of the inverter, the computation and PWM sampling delays are included in the controller design. Finally, various case studies are provided that verify the performance of the proposed approach and the stability of the system.

scholarly journals An Integrated Design Approach for LCL-Type Inverter to Improve Its Adaptation in Weak Grid

Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2637
Author(s):  
Zheng ◽  
Liu ◽  
Liu ◽  
Li ◽  
Dai ◽  
...  
Keyword(s):  
Design Method ◽  
Robustness Analysis ◽  
Integrated Design ◽  
System Stability ◽  
Lcl Filter ◽  
Weak Grid ◽  
Grid Impedance ◽  
Integrated Design Approach ◽  
Simulation And Experiment ◽  
Grid Connected Inverter

To improve the robustness of grid-connected inverter against grid impedance in a weak grid an integrated design method of LCL-filter parameters and controller parameters is proposed. In the method the inherent relation of LCL-filter parameters and controller parameters is taken into consideration to realize their optimized match. A parameter normalization scheme is also developed to facilitate the system stability and robustness analysis. Based on the method all normalization parameters can be designed succinctly according to the required stability and robustness. Additionally, the LCL parameter and controller parameter can be achieved immediately by restoring normalization parameters. The proposed design method can guarantee the inverter stability and robustness simultaneously without needing any compensation network, additional hardware, or the complicated iterative computations which cannot be avoided for the conventional inverter design method. Simulation and experiment results have validated the superiority of the proposed inverter design method.

Resistance Monitor and Control for Vacuum Evaporation of Metals and Carbon

1976 ◽  
Vol 34 ◽  
pp. 572-573
Author(s):  
Russell L. Steere ◽  
Eric F. Erbe ◽  
J. Michael Moseley
Keyword(s):  
Electronic Device ◽  
Point Sources ◽  
High Contrast ◽  
Variable Resistor ◽  
Quality Of Results ◽  
Low Contrast ◽  
Evaporation Source ◽  
And Control ◽  
At Will

We have designed and built an electronic device which compares the resistance of a defined area of vacuum evaporated material with a variable resistor. When the two resistances are matched, the device automatically disconnects the primary side of the substrate transformer and stops further evaporation.This approach to controlled evaporation in conjunction with the modified guns and evaporation source permits reliably reproducible multiple Pt shadow films from a single Pt wrapped carbon point source. The reproducibility from consecutive C point sources is also reliable. Furthermore, the device we have developed permits us to select a predetermined resistance so that low contrast high-resolution shadows, heavy high contrast shadows, or any grade in between can be selected at will. The reproducibility and quality of results are demonstrated in Figures 1-4 which represent evaporations at various settings of the variable resistor.

Boilerplate

2012 ◽  
Author(s):  
Margaret Jane Radin
Keyword(s):  
Economic Efficiency ◽  
Analytical Framework ◽  
Daily Basis ◽  
Regulatory Agencies ◽  
Jury Trial ◽  
Comprehensive Treatment ◽  
New Methods ◽  
And Control ◽  
Fine Print

Boilerplate—the fine-print terms and conditions that we become subject to when we click “I agree” online, rent an apartment, or enter an employment contract, for example—pervades all aspects of our modern lives. On a daily basis, most of us accept boilerplate provisions without realizing that should a dispute arise about a purchased good or service, the nonnegotiable boilerplate terms can deprive us of our right to jury trial and relieve providers of responsibility for harm. Boilerplate is the first comprehensive treatment of the problems posed by the increasing use of these terms, demonstrating how their use has degraded traditional notions of consent, agreement, and contract, and sacrificed core rights whose loss threatens the democratic order. This book examines attempts to justify the use of boilerplate provisions by claiming either that recipients freely consent to them or that economic efficiency demands them, and it finds these justifications wanting. It argues that our courts, legislatures, and regulatory agencies have fallen short in their evaluation and oversight of the use of boilerplate clauses. To improve legal evaluation of boilerplate, the book offers a new analytical framework, one that takes into account the nature of the rights affected, the quality of the recipient's consent, and the extent of the use of these terms. It goes on to offer possibilities for new methods of boilerplate evaluation and control, and concludes by discussing positive steps that NGOs, legislators, regulators, courts, and scholars could take to bring about better practices.

Management and engineering solutions to improve processing stock quality and reduce resource-intensity of mining

2018 ◽  
pp. 56-68
Author(s):  
V. V. Agafonov ◽  
V. Yu. Zalyadinov ◽  
M. E. Yusupov ◽  
N. S. Bikteeva
Keyword(s):  
Development Strategy ◽  
Open Pit ◽  
Mining Operations ◽  
High Concern ◽  
General Production ◽  
Resource Intensity ◽  
Product Output ◽  
And Control ◽  
A Company

Sustainability of mining companies is of of high concern. The problem is specifically acute at companies that are monotownor monosettlement-forming. Sustainability of a mine depends in many ways on product quality and production resource-intensity. This article discusses formation of mineral quality indexes in terms of an open pit chrysotile mine. The studies took into account specific features of operation procedures implemented by each structural division of the mine. The analysis has found managerial and technological inconsistencies which affect quality and marketable product output, as well as efficiency of the mine in whole. The background for efficiency enhancement at a company is, by the authors’ opinion, consolidation of personnel subject to the single development strategy, namely: improvement of production and control efficiency, as well as use of available reserves and resources by means of better setup for production. The proposed approaches to planning mining operations and forming mineral quality allow higher quality of processing stock. In addition, a new model proposed for interaction between structural divisions of a mining company ensures improvement of general production indexes.

EFFICIENT MANAGEMENT SYSTEM OF TEACHING TECHNICAL MEANS AT CENTRAL KINDERGARTEN PEDAGOGY COLLEGE IN INDUSTRIAL REVOLUTION 4.0

2020 ◽  
Vol 9 (2) ◽  
Author(s):  
Vũ Xuân Hùng
Keyword(s):  
Intellectual Development ◽  
Industrial Revolution ◽  
Current Period ◽  
Efficient Management ◽  
Urgent Task ◽  
Creative Learning ◽  
Cognitive Activities ◽  
And Control ◽  
Technical Teaching

In the process of teaching, technical teaching facilities are both a content and a means of conveying information, they help the lecturer organize and control the students' cognitive activities, in addition, they also help students be interested in learning, practice practical skills from which to form active and creative learning methods. Teaching technology is one of the necessary conditions to help teachers carry out their related work of educating, teaching and bringing up, and intellectual development, arouse the inherent intelligence qualities of students. Currently, the management of technical teaching facilities at the Central Kindergartens College has been carried out on a regular basis and achieved certain results, but in fact, there are still many inadequacies. Finding a number of limitations in the management of teaching technical facilities, thereby proposing solutions to overcome those limitations, improve the efficiency of investment, preservation and use of teaching technical facilities in the trend of Industry Revolution 4.0, improving the quality of teaching at Central Kindergarten Pedagogy colleges in the current period is a very important and urgent task.

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