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Proceedings ArticleDOI

Voltage regulation and stabilization of DC/DC buck converter under constant power loading

01 Dec 2014-pp 1-6

AbstractThe low and medium voltage renewable energy based dc distribution systems are catching increased attention world-wide due to their inherent benefits over ac systems. Higher efficiency, simple control, more suitable for integration of the sources producing dc power, are some of the main benefits of the dc systems. However, these systems are prone to serious stability issues caused by the constant power load (CPL) nature of the point-of-load converters (POLs). This paper deals with the stabilization and voltage regulation of dc/dc buck converter feeding a combination of the constant voltage resistive load (CVL) and CPL in a dc micro-grid application. A sliding mode controller is proposed which ensures supply of constant power demanded by the CPL and tight voltage regulation (error less than 0.1 V) of the output voltage. The effectiveness of the controller is validated through simulation results under different operating conditions. It is shown that the controller is robust to the large changes in supply voltage and the load.

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Citations
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Journal ArticleDOI
Abstract: The penetration of dc distributed power systems is increasing rapidly in electric power grids and other isolated systems to cater demand for cheap, clean, high quality, and uninterrupted power demand of modern society. DC systems are more efficient and suite better to integrate some of the renewable energy sources, storage units, and dc loads. A dc distributed power system usually consists of large number of power electronic converters connected in cascad0ed configuration to satisfy the power quality and voltage magnitude requirements of the sources and loads. Tightly-regulated power converters in the aforementioned settings exhibit negative incremental impedance and behave as constant power loads (CPLs), and tend to destabilize their feeder systems and upstream converters. The presence of CPLs reduces effective damping of the system leading to instability of the whole system and present significant challenge in the system operation and control. In-depth knowledge of the instability effects of constant power loads (CPLs), available stabilizing techniques and stability analysis methods, is imperious to the young researchers, system designers, system integrators, and practicing engineers working in the field of dc power systems and emerging applications of dc power. This paper is intended to fill this gape by documenting present state of the art and research needs in one article. Modeling, behaviour and effects of typical CPL are discussed and a review of stability criteria used to study the stability of dc power systems are reviewed with their merits and limitations. Furthermore, available literature is reviewed to summarize the techniques to compensate the CPL effect. Finally, discussion and recent challenges in the dc distribution systems.

99 citations


Cites background from "Voltage regulation and stabilizatio..."

  • ...Authors in [92], have proposed a PWM based sliding mode control using a nonlinear switching function, to mitigate negative impedance instabilities in a dc/dc buck converter supplying mixed load (CPL and CVL)....

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Journal ArticleDOI
19 Oct 2017-Energies
Abstract: This paper provides a comprehensive review of the major concepts associated with the μgrid, such as constant power load (CPL), incremental negative resistance or impedance (INR/I) and its dynamic behaviours on the μgrid, and power system distribution (PSD). In general, a μgrid is defined as a cluster of different types of electrical loads and renewable energy sources (distributed generations) under a unified controller within a certain local area. It is considered a perfect solution to integrate renewable energy sources with loads as well as with a traditional grid. In addition, it can operate with a conventional grid, for example, by energy sourcing or a controllable load, or it can operate alone as an islanding mode to feed required electric energy to a grid. Hence, one of the important issues regarding the μgrid is the constant power load that results from the tightly designed control when it is applied to power electronic converters. The effect of CPL is incremental negative resistance that impacts the power quality of a power system and makes it at negative damping. Also, in this paper, a comprehensive study on major control and compensation techniques for μgrid has been included to face the instability effects of constant power loads. Finally, the merits and limitations of the compensation techniques are discussed.

61 citations


Cites background from "Voltage regulation and stabilizatio..."

  • ...In [77] the stable sliding surface (s), shown in Figure 13a, is designed to obtain system control law (u) is to meet the system stability requirements with reference values for the inductor current and capacitor voltage....

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Journal ArticleDOI
TL;DR: It is found that the proposed control scheme ensures desired operation of the DC micro-grid under various operating modes and maintains system stability with CPL under variations in the primary resource and load demand.
Abstract: In recent years DC micro-grid has been widely accepted as one of the promising solutions to integrate renewable energy sources and to supply power to critical loads such as data centres, remote villages and communication stations However, DC micro-grid has a fundamental stability challenge due to constant power load (CPL) characteristics of point-of-load converters, which introduce destabilising effect in the system This study presents a sliding mode control based non-linear control scheme for a solar photo-voltaic based DC micro-grid in the presence of CPLs The objective of the proposed control scheme is to tightly regulate the DC bus voltage and mitigate the destabilising effects of CPLs The stability of the system is analytically established and a limit of CPL is obtained Furthermore, a charging/discharging algorithm is implemented for battery bank interfacing bidirectional converter which facilitates three modes charging namely constant current, constant voltage, and float mode, to enhance the battery life The validation of the effectiveness of the proposed scheme is done through simulation and experimental results It is found that the proposed control scheme ensures desired operation of the DC micro-grid under various operating modes and maintains system stability with CPL under variations in the primary resource and load demand

24 citations

Proceedings ArticleDOI
01 Nov 2017
TL;DR: The fuzzy logic controller is design to ensure the stabilization of buck converter under change the constant power load and tight voltage regulation after transient response by choosing the proper duty cycle for each cycle.
Abstract: Load converter is the second stage of multiconverter electronic power system. Under tight control, the converter acts as constant power load (CPL). The CPL has innate incremental negative resistance properties (INR). The INR influence the power quality of system. In this paper, the proposed fuzzy logic controller aims to regulate the voltage of dc-dc buck converter which is feeding the CPL and the resistive load. The fuzzy logic controller is design to ensure the stabilization of buck converter under change the constant power load and tight voltage regulation after transient response by choosing the proper duty cycle for each cycle. The fuzzy logic controller is validated by simulation in MATLAB/Simulink.

20 citations

Proceedings ArticleDOI
07 Jun 2015
Abstract: The paper presents a robust sliding mode controller for a dc/dc, bidirectional converter interfacing storage unit to ensure dc bus voltage regulation in a stand-alone dc microgrid. The dc bus supplies a combination of a constant power load and conventional resistive load. In order to enhance the battery life, a state-of-charge based charging algorithm is also implemented. Depending on the measured dc bus voltage, the controller selects the appropriate operating mode of the converter. The effectiveness of the proposed controller has been validated through simulation results.

18 citations


References
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Book
01 Jan 1978
TL;DR: An electric dynamically operated storage element comprises two energy stores and circuitry is provided for applying periodically repeating phase clock pulses simultaneously to the energy stores through the charging circuits.
Abstract: An electric dynamically operated storage element comprises two energy stores. Each store has a charging circuit including a rectifying element and a discharging circuit including a controlled respectively variable resistance connected in series with the rectifying element. Also, circuitry is provided for applying periodically repeating phase clock pulses simultaneously to the energy stores through the charging circuits.

1,789 citations


"Voltage regulation and stabilizatio..." refers methods in this paper

  • ...Sliding mode control (SMC) is a well known technique to design robust controllers [8], [9]....

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Book
01 Jan 1976
TL;DR: This book is referred to read because it is an inspiring book to give you more chance to get experiences and also thoughts and this is not only this control systems of variable structure.
Abstract: Downloading the book in this website lists can give you more advantages. It will show you the best book collections and completed collections. So many books can be found in this website. So, this is not only this control systems of variable structure. However, this book is referred to read because it is an inspiring book to give you more chance to get experiences and also thoughts. This is simple, read the soft file of the book and you get it.

762 citations


"Voltage regulation and stabilizatio..." refers methods in this paper

  • ...Sliding mode control (SMC) is a well known technique to design robust controllers [8], [9]....

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Journal ArticleDOI
TL;DR: Sliding-mode and feedback linearization techniques along with large-signal phase plane analysis are presented as methods to analyze, control, and stabilize automotive converters/systems operating with CPLs.
Abstract: Power electronic converters and electric motor drives are being put into use at an increasingly rapid rate in advanced automobiles. However, the new advanced automotive electrical systems employ multivoltage level hybrid ac and dc as well as electromechanical systems that have unique characteristics, dynamics, and stability problems that are not well understood due to the nonlinearity and time dependency of converters and because of their constant power characteristics. The purpose of this paper is to present an assessment of the negative impedance instability concept of the constant power loads (CPLs) in automotive power systems. The main focus of this paper is to analyze and propose design criteria of controllers for automotive converters/systems operating with CPLs. The proposed method is to devise a new comprehensive approach to the applications of power electronic converters and motor drives in advanced automotive systems. Sliding-mode and feedback linearization techniques along with large-signal phase plane analysis are presented as methods to analyze, control, and stabilize automotive converters/systems with CPLs

696 citations


"Voltage regulation and stabilizatio..." refers background or methods in this paper

  • ...Sliding mode control approach have also been applied to stabilize dc/dc converters against CPL induced instabilities [1], [2], [7], [10]–[15]....

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  • ...in [1] have proposed a SMC which ensures the supply of the constant power needed the CPL, however, proposed controller does not maintain a constant voltage....

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  • ...The current drawn by the CPLs increases/decreases with the decrease/increase in the voltage across its terminals which may cause limit cycles in the voltage and current and may lead to instability of the overall system even if individual converters are stable [1]–[7]....

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Journal ArticleDOI
Abstract: This paper explores stability issues in dc microgrids with instantaneous constant-power loads (CPLs). DC microgrids typically have distributed power architectures in which point-of-load converters behave as instantaneous CPLs to line regulating converters located upstream. Constant-power loads introduce a destabilizing effect in dc microgrids that may cause their main bus voltages to show significant oscillations or to collapse. This paper also discusses stabilization strategies to prevent these undesired behaviors from occurring. Mitigating strategies such as load shedding, addition of resistive loads, filters, or energy storage directly connected to the main bus, and control methods are investigated. Advantages and disadvantages of these methods are discussed and recommendations are made. The analysis is verified with simulations and hardware-based experiments.

447 citations


"Voltage regulation and stabilizatio..." refers methods in this paper

  • ...Sliding mode control approach have also been applied to stabilize dc/dc converters against CPL induced instabilities [1], [2], [7], [10]–[15]....

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Journal ArticleDOI
Abstract: With the development of renewable energy, dc distribution power system (DPS) becomes more and more attractive. The stability of whole system is still a big concern though every single converter is well designed based on the stand-alone operation with sufficient stability. Since the cascaded connection of power converters is one of the most dominant connection forms in the dc DPS, the stability analysis of the cascaded system is very important to ensure stability of the whole system. Based on the Lyapunov linearization method and Brayton–Moser's mixed potential theory, stability of equilibrium point and an estimation of the region of attraction are investigated for cascaded system in the dc DPS. Based on the analysis, stability prediction criteria for cascaded system under small-signal and large-signal disturbances are obtained. The two criteria are simple and straightforward, which can be unified to get a general stability criterion to predict system's stability under both small-signal and large-signal transient disturbances. The relationship between system parameters and the stability is presented and discussed in the paper. Therefore, instead of trial and error, the proposed criterion can predict and guarantee the stability operation of cascaded system during the design process, and it is also helpful to select matched power converters in system level design. The simulation and experimental results verify the effectiveness of the proposed criterion.

164 citations


"Voltage regulation and stabilizatio..." refers methods in this paper

  • ...Some of the techniques among many others, proposed in the literature for the stabilization of the CPL induced instabilities are power shaping based Brayton-Mayer’s mixed potential function [3], coupling induced open loop stabilization [5], [6], and sliding mode control....

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