Maximising energy capture from distributed generators in weak networks
20 Dec 2004-Vol. 151, Iss: 5, pp 611-618
TL;DR: The paper discusses the implications of the increasing capacity of synchronous generators at the remote ends of rural distribution networks where the line resistances are high and the X/R ratios are low and proposed approaches may increase the export of real power while maintaining voltage within the statutory limits.
Abstract: The paper discusses the implications of the increasing capacity of synchronous generators at the remote ends of rural distribution networks where the line resistances are high and the X/R ratios are low. Local voltage variation is specifically examined and two methods of compensation are proposed. The first of them is a deterministic system that uses a set of rules to switch intelligently between voltage and power factor control modes, while the second is based on a fuzzy inference system that adjusts the reference setting of the automatic power factor controller in response to the terminal voltage. Extensive simulations have verified that the proposed approaches may increase the export of real power while maintaining voltage within the statutory limits.
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TL;DR: In this paper, a distributed automatic control approach is proposed to alleviate the voltage rise caused by active power injection in distribution networks with distributed generation, where the objective is not to control bus voltage but to guarantee that generator injections alone do not cause significant voltage rise.
Abstract: This paper addresses the problem of voltage rise mitigation in distribution networks with distributed generation. A distributed automatic control approach is proposed to alleviate the voltage rise caused by active power injection. The objective of the proposed approach is not to control bus voltage but to guarantee that generator injections alone do not cause significant voltage rise: a solution in which distribution network operators (DNOs) are kept to their traditional task of voltage regulation for load demand. The approach is discussed in the perspective of effectiveness and adequacy. Its consequences to DNO control effort are evaluated. Illustration is provided for a single feeder with stochastic generation and transformer on-load tap-changing voltage regulation.
613 citations
Cites background from "Maximising energy capture from dist..."
...More complex distributed approaches have been proposed to control the target voltage of automatic voltage control relays at primary substations [6] and to combine fixed power factor with automatic voltage control [7]....
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TL;DR: In this article, the authors compared the performance of reactive power control and intelligent distributed voltage control in terms of the potential for connecting increased capacities within existing networks. And they showed that the results obtained by the reactive control gave similar results to those obtained by centralized management in the case of the DG.
Abstract: With the rapid increase in distributed generation (DG), the issue of voltage regulation in the distribution network becomes more significant, and centralized voltage control (or active network management) is one of the proposed methods. Alternative work on intelligent distributed voltage and reactive power control of DG has also demonstrated benefits in terms of the minimization of voltage variation and violations as well as the ability to connect larger generators to the distribution network. This paper uses optimal power flow to compare the two methods and shows that intelligent distributed voltage and reactive power control of the DG gives similar results to those obtained by centralized management in terms of the potential for connecting increased capacities within existing networks
549 citations
Cites background from "Maximising energy capture from dist..."
...C. Alternative Voltage Control 1) ‘Intelligent’ Distributed Voltage/Power Factor Control Kiprakis and Wallace [5] proposed a voltage control method for DGs, which assumes a more flexible attitude from DNOs concerning the voltage control by DGs....
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...1) “Intelligent” Distributed Voltage/Power Factor Control: Kiprakis and Wallace [5] proposed a voltage control method Fig....
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...The authors are with the Institute for Energy Systems, Joint Research Institute for Energy, School of Engineering & Electronics, University of Edinburgh, Edinburgh EH9 3JL, UK, (emails: Aristides.Kiprakis@ed.ac.uk, panaghs@gmail.com, Gareth.Harrison@ed.ac.uk, Robin.Wallace@ed.ac.uk). employ state estimation to assess voltage profile and dispatch DG and other network elements accordingly [4]....
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...Previously published work [5] demonstrates the benefits in terms of the minimization of steady-state voltage variations (and violations) as well as the ability to connect larger generators to the distribution network....
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...While optimal power flow (OPF) is traditionally used as an operating tool in power systems, Harrison and Wallace [6] presented a means of using it to assess the availability of network capacity to accept DG....
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TL;DR: In this paper, the authors provide an overview of the current state of research in the field of ocean energy and highlight areas where research gaps exist and where future research efforts should be directed to.
Abstract: The oceans of the earth offer vast amounts of renewable energy. Technologies to harness the power of the seas are at an early stage of development. Even the most advances technologies, namely tidal current and ocean wave still face considerable barriers and many obstacles remain. Research, development and innovation can help overcome those barriers. This review provides an overview over the current state of research in the field of ocean energy. In particular, the authors focus on research beyond technology or technological improvements. This article also highlights areas where research gaps exists and where future research efforts should be directed to.
349 citations
Cites background from "Maximising energy capture from dist..."
...Demands on the control ocean energy converters and arrays will be of high importance [76]....
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...This may lead to a limitation of the electricity delivered to the grid due to quality of supply [75,76]....
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TL;DR: In this paper, the authors present a detailed review of the control strategies that are being utilized to mitigate voltage regulation challenges when increased amount of renewable DGs are connected within the distribution network.
Abstract: Integration of renewable energy sources (RES) into traditional power system is one of the most viable technologies to meet the ever increasing energy demand efficiently. But, this technology arises a lot of challenges which are necessary to be taken care of for smooth operation of the network. Voltage regulation is the most significant technical challenge that tends to limit the amount of penetration of renewable distribution generators (DGs) into the distribution network. This paper attempts to present a detailed review of the control strategies that are being utilized to mitigate voltage regulation challenges when increased amount of renewable DGs are connected within the distribution network. This study analyses the direct impacts of increased accommodation of renewable DGs on the distribution network operation and evaluates current research status of voltage control strategies. Then qualitative analysis is performed for all kinds of voltage control approaches involving their pros and cons for the first time. The objective of this contribution is to present the latest research status of distribution system voltage control strategies with highly penetrated renewable DGs and a brief review of different control methodologies.
263 citations
TL;DR: The proposed distributed scheme successfully mitigates overvoltage situations due to high PV penetration and performs almost as well as the OPF-based solution with significantly less information and communication requirements.
Abstract: In this paper, the overvoltage problems that might arise from the integration of photovoltaic (PV) panels into low-voltage (LV) distribution networks is addressed. A distributed scheme is proposed that adjusts the reactive and active power output of inverters to prevent or alleviate such problems. The proposed scheme is model-free and makes use of limited communication between the controllers in the form of a distress signal only during emergency conditions. It prioritizes the use of reactive power, while active power curtailment is performed only as a last resort. The behavior of the scheme is studied using dynamic simulations on a single LV feeder and on a larger network composed of 14 LV feeders. Its performance is compared with a centralized scheme based on the solution of an optimal power flow (OPF) problem, whose objective function is to minimize the active power curtailment. The proposed scheme successfully mitigates overvoltage situations due to high PV penetration and performs almost as well as the OPF-based solution with significantly less information and communication requirements.
260 citations
Cites methods from "Maximising energy capture from dist..."
...Finally, a comparison between an OPFbased centralized scheme and the distributed scheme of [28] is performed in [29]....
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References
More filters
01 Jan 1985
TL;DR: A mathematical tool to build a fuzzy model of a system where fuzzy implications and reasoning are used is presented and two applications of the method to industrial processes are discussed: a water cleaning process and a converter in a steel-making process.
Abstract: A mathematical tool to build a fuzzy model of a system where fuzzy implications and reasoning are used is presented. The premise of an implication is the description of fuzzy subspace of inputs and its consequence is a linear input-output relation. The method of identification of a system using its input-output data is then shown. Two applications of the method to industrial processes are also discussed: a water cleaning process and a converter in a steel-making process.
18,803 citations
Book•
01 Jan 1989
TL;DR: Presents extensive and updated material concerned with the methodology and algorithms of fuzzy sets considered mainly in the context of control engineering and system modeling and analysis.
Abstract: From the Publisher:
Presents extensive and updated material concerned with the methodology and algorithms of fuzzy sets considered mainly in the context of control engineering and system modeling and analysis. Offers information on fuzzy sets and the concept of fuzzy control, reviewing selected applications and their origin. Discusses design aspects and theoretical developments in the design of fuzzy controllers. Includes comprehensive coverage of the paradigms and algorithms of fuzzy modeling.
1,097 citations
Book•
01 Jan 1992
TL;DR: The model structures presented are intended to facilitate the use of field test data as a means of obtaining model parameters and do not represent all of the control loops on any particular system.
Abstract: Excitation system models suitable for use in large-scale system stability studies are presented. Important limiters and supplementary controls are also included. The model structures presented are intended to facilitate the use of field test data as a means of obtaining model parameters. The models are, however, reduced order models and do not represent all of the control loops on any particular system. The models are valid for frequency deviations of ±5% from rated frequency and oscillation frequencies up to 3 Hz. These models would not normally be adequate for use in studies of subsynchronous resonance or other shaft torsional interaction problems. Delayed protective and control features that may come into play in long term dynamic performance studies are not represented. A sample set of data for each of the models, for at least one particular application, is provided.
889 citations
TL;DR: In this paper, the authors summarized the results of some generic studies, explaining the voltage rise issue and how it may be overcome, and proposed methods to counteract voltage rise are primary substation voltage reduction, reactive power import, autotransformers installation, conductor upgrading, and generation constraints.
Abstract: There has been much interest in embedding small generators deep within distribution systems. The steady-state voltage rise resulting from the connection of these generators can be a major obstacle to their connection at the lower voltage levels. This article summarises the results of some generic studies, explaining this voltage rise issue and how it may be overcome. Methods discussed to counteract voltage rise are primary substation voltage reduction, reactive power import, autotransformers installation, conductor upgrading, and generation constraints.
660 citations
TL;DR: An in-depth analysis on a class of nonlinear variable gain proportional-derivative (PD) controllers, which shows how to analyze the characteristics of the variable gains in the context of control and how to generate various gain variation characteristics through the manipulation of the rule proportionality.
Abstract: We investigated the analytical structure of the Takagi-Sugeno (TS) type of fuzzy controllers, which was unavailable in the literature. The TS fuzzy controllers we studied employ a new and simplified TS control rule scheme in which all the rule consequent use a common function and are proportional to one another, greatly reducing the number of parameters needed in the rules. Other components of the fuzzy controllers are general: arbitrary input fuzzy sets, any type of fuzzy logic, and the generalized defuzzifier, which contains the popular centroid defuzzifier as a special case. We proved that all these TS fuzzy controllers were nonlinear variable gain controllers and characteristics of the gain variation were parametrized and governed by the rule proportionality. We conducted an in-depth analysis on a class of nonlinear variable gain proportional-derivative (PD) controllers. We present the results to show: (1) how to analyze the characteristics of the variable gains in the context of control; (2) why the nonlinear variable gain PD controllers can outperform their linear counterpart; and (3) how to generate various gain variation characteristics through the manipulation of the rule proportionality.
125 citations