Power Management Strategies for a Microgrid With Multiple Distributed Generation Units
TL;DR: In this article, real and reactive power management strategies of EI-DG units in the context of a multiple DG microgrid system were investigated. And the results were used to discuss applications under various microgrid operating conditions.
Abstract: This paper addresses real and reactive power management strategies of electronically interfaced distributed generation (DG) units in the context of a multiple-DG microgrid system. The emphasis is primarily on electronically interfaced DG (EI-DG) units. DG controls and power management strategies are based on locally measured signals without communications. Based on the reactive power controls adopted, three power management strategies are identified and investigated. These strategies are based on 1) voltage-droop characteristic, 2) voltage regulation, and 3) load reactive power compensation. The real power of each DG unit is controlled based on a frequency-droop characteristic and a complimentary frequency restoration strategy. A systematic approach to develop a small-signal dynamic model of a multiple-DG microgrid, including real and reactive power management strategies, is also presented. The microgrid eigen structure, based on the developed model, is used to 1) investigate the microgrid dynamic behavior, 2) select control parameters of DG units, and 3) incorporate power management strategies in the DG controllers. The model is also used to investigate sensitivity of the design to changes of parameters and operating point and to optimize performance of the microgrid system. The results are used to discuss applications of the proposed power management strategies under various microgrid operating conditions
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TL;DR: In this paper, a detailed analysis of the main operation modes and control structures for power converters belonging to micro-grids is carried out, focusing mainly on grid-forming, grid-feeding, and grid-supporting configurations.
Abstract: The enabling of ac microgrids in distribution networks allows delivering distributed power and providing grid support services during regular operation of the grid, as well as powering isolated islands in case of faults and contingencies, thus increasing the performance and reliability of the electrical system. The high penetration of distributed generators, linked to the grid through highly controllable power processors based on power electronics, together with the incorporation of electrical energy storage systems, communication technologies, and controllable loads, opens new horizons to the effective expansion of microgrid applications integrated into electrical power systems. This paper carries out an overview about microgrid structures and control techniques at different hierarchical levels. At the power converter level, a detailed analysis of the main operation modes and control structures for power converters belonging to microgrids is carried out, focusing mainly on grid-forming, grid-feeding, and grid-supporting configurations. This analysis is extended as well toward the hierarchical control scheme of microgrids, which, based on the primary, secondary, and tertiary control layer division, is devoted to minimize the operation cost, coordinating support services, meanwhile maximizing the reliability and the controllability of microgrids. Finally, the main grid services that microgrids can offer to the main network, as well as the future trends in the development of their operation and control for the next future, are presented and discussed.
2,621 citations
Cites background from "Power Management Strategies for a M..."
...can be potentially connected to any point of the power system [3]–[5]....
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TL;DR: The major issues and challenges in microgrid control are discussed, and a review of state-of-the-art control strategies and trends is presented; a general overview of the main control principles (e.g., droop control, model predictive control, multi-agent systems).
Abstract: The increasing interest in integrating intermittent renewable energy sources into microgrids presents major challenges from the viewpoints of reliable operation and control. In this paper, the major issues and challenges in microgrid control are discussed, and a review of state-of-the-art control strategies and trends is presented; a general overview of the main control principles (e.g., droop control, model predictive control, multi-agent systems) is also included. The paper classifies microgrid control strategies into three levels: primary, secondary, and tertiary, where primary and secondary levels are associated with the operation of the microgrid itself, and tertiary level pertains to the coordinated operation of the microgrid and the host grid. Each control level is discussed in detail in view of the relevant existing technical literature.
2,358 citations
Cites background or methods from "Power Management Strategies for a M..."
...and denote droop coefficients, and are determined based on steady-state performance criteria [56], [72], [76]....
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...tion loop is proposed in [76] to maintain the system frequency at the nominal value....
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...One active power management strategy ( - droop) and three reactive power management strategies ( - droop, voltage regulation, and power factor correction) are proposed in [76], [95]....
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TL;DR: Decentralized, distributed, and hierarchical control of grid-connected and islanded microgrids that mimic the behavior of the mains grid is reviewed.
Abstract: This paper presents a review of advanced control techniques for microgrids. This paper covers decentralized, distributed, and hierarchical control of grid-connected and islanded microgrids. At first, decentralized control techniques for microgrids are reviewed. Then, the recent developments in the stability analysis of decentralized controlled microgrids are discussed. Finally, hierarchical control for microgrids that mimic the behavior of the mains grid is reviewed.
1,702 citations
Cites background from "Power Management Strategies for a M..."
...to restore the system frequency and voltage to nominal values following a load change [11], [12]....
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TL;DR: This work provides a comprehensive overview of fundamental principles that underpin blockchain technologies, such as system architectures and distributed consensus algorithms, and discusses opportunities, potential challenges and limitations for a number of use cases, ranging from emerging peer-to-peer energy trading and Internet of Things applications, to decentralised marketplaces, electric vehicle charging and e-mobility.
Abstract: Blockchains or distributed ledgers are an emerging technology that has drawn considerable interest from energy supply firms, startups, technology developers, financial institutions, national governments and the academic community. Numerous sources coming from these backgrounds identify blockchains as having the potential to bring significant benefits and innovation. Blockchains promise transparent, tamper-proof and secure systems that can enable novel business solutions, especially when combined with smart contracts. This work provides a comprehensive overview of fundamental principles that underpin blockchain technologies, such as system architectures and distributed consensus algorithms. Next, we focus on blockchain solutions for the energy industry and inform the state-of-the-art by thoroughly reviewing the literature and current business cases. To our knowledge, this is one of the first academic, peer-reviewed works to provide a systematic review of blockchain activities and initiatives in the energy sector. Our study reviews 140 blockchain research projects and startups from which we construct a map of the potential and relevance of blockchains for energy applications. These initiatives were systematically classified into different groups according to the field of activity, implementation platform and consensus strategy used. 1 Opportunities, potential challenges and limitations for a number of use cases are discussed, ranging from emerging peer-to-peer (P2P) energy trading and Internet of Things (IoT) applications, to decentralised marketplaces, electric vehicle charging and e-mobility. For each of these use cases, our contribution is twofold: first, in identifying the technical challenges that blockchain technology can solve for that application as well as its potential drawbacks, and second in briefly presenting the research and industrial projects and startups that are currently applying blockchain technology to that area. The paper ends with a discussion of challenges and market barriers the technology needs to overcome to get past the hype phase, prove its commercial viability and finally be adopted in the mainstream.
1,399 citations
Journal Article•
TL;DR: Depending on the type and depth of penetration of distributed energy resource units, load characteristics and power quality constraints, and market participation strategies, the required control and operational strategies of a microgrid can be significantly, and even conceptually, different than those of the conventional power systems.
Abstract: The environmental and economical benefits of the microgrid and consequently its acceptability and degree of proliferation in the utility power industry, are primarily determined by the envisioned controller capabilities and the operational features. Depending on the type and depth of penetration of distributed energy resource (DER) units, load characteristics and power quality constraints, and market participation strategies, the required control and operational strategies of a microgrid can be significantly, and even conceptually, different than those of the conventional power systems.
1,335 citations
References
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Book•
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TL;DR: In this article, the authors present a model for the power system stability problem in modern power systems based on Synchronous Machine Theory and Modelling, and a model representation of the synchronous machine representation in stability studies.
Abstract: Part I: Characteristics of Modern Power Systems. Introduction to the Power System Stability Problem. Part II: Synchronous Machine Theory and Modelling. Synchronous Machine Parameters. Synchronous Machine Representation in Stability Studies. AC Transmission. Power System Loads. Excitation in Stability Studies. Prime Mover and Energy Supply Systems. High-Voltage Direct-Current Transmission. Control of Active Power and Reactive Power. Part III: Small Signal Stability. Transient Stability. Voltage Stability. Subsynchronous Machine Representation in Stability Studies. AC Transmission. Power System Loads. Excitation in Stability Studies. Prime Mover and Energy Supply Systems, High-Voltage Direct-Current Transmission. Control of Active Power and Reactive Power. Part III: Small Signal Stability. Transient Stability. Voltage Stability. Subsynchronous Oscillations. Mid-Term and Long-Term Stability. Methods of Improving System Stability.
13,467 citations
01 Jan 2002
TL;DR: Theory of brushless dc motors and dc machines is discussed in this article, where the authors present a general framework for electric machine analysis based on basic principles for Electric Machine Analysis.
Abstract: Preface.Basic Principles for Electric Machine Analysis.Direct--Current Machines.Reference--Frame Theory.Symmetrical Induction Machines.Synchronous Machines.Theory of Brushless dc Machines.Machine Equations in Operational Impedances and Time Constants.Linearized Machine Equations.Reduced--Order Machine Equations.Symmetrical and Unsymmetrical 2--Phase Induction Machines.Semicontrolled Bridge Converters.dc Machine Drives.Fully Controlled 3--Phase Bridge Converters.Induction Motor Drives.Brushless dc Motor Drives.Appendix: Trigonometric Relations, Constants and Conversion Factors, and Abbreviations.Index.
3,147 citations
"Power Management Strategies for a M..." refers methods in this paper
...The dynamic model of a conventional DG unit is described in [16], and the detailed procedure to construct (26) from the ODEs representing each block is given in [8]....
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20 Jun 2004
TL;DR: In this article, the authors propose a system approach which views generation and associated loads as a subsystem or a "microgrid". During disturbances, the generation and corresponding loads can separate from the distribution system to isolate the microgrid's load from the disturbance (providing UPS services) without harming the transmission grid's integrity.
Abstract: Application of individual distributed generators can cause as many problems as it may solve. A better way to realize the emerging potential of distributed generation is to take a system approach which views generation and associated loads as a subsystem or a "microgrid". During disturbances, the generation and corresponding loads can separate from the distribution system to isolate the microgrid's load from the disturbance (providing UPS services) without harming the transmission grid's integrity. This ability to island generation and loads together has a potential to provide a higher local reliability than that provided by the power system as a whole. In this model it is also critical to be able to use the waste heat by placing the sources near the heat load. This implies that a unit can be placed at any point on the electrical system as required by the location of the heat load.
1,685 citations
"Power Management Strategies for a M..." refers background in this paper
...PROLIFERATION of distributed resource (DR) units in the form of distributed generation (DG), distributed storage (DS), or a hybrid of DG and DS units has brought about the concept of microgrid [1]–[3]....
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TL;DR: In this paper, the authors investigated preplanned switching events and fault events that lead to islanding of a distribution subsystem and formation of a micro-grid, and they concluded that an appropriate control strategy for the power electronically interfaced DG unit can ensure stability of the microgrid and maintain voltage quality at designated buses, even during islanding transients.
Abstract: This paper investigates (i) preplanned switching events and (ii) fault events that lead to islanding of a distribution subsystem and formation of a micro-grid. The micro-grid includes two distributed generation (DG) units. One unit is a conventional rotating synchronous machine and the other is interfaced through a power electronic converter. The interface converter of the latter unit is equipped with independent real and reactive power control to minimize islanding transients and maintain both angle stability and voltage quality within the micro-grid. The studies are performed based on a digital computer simulation approach using the PSCAD/EMTDC software package. The studies show that an appropriate control strategy for the power electronically interfaced DG unit can ensure stability of the micro-grid and maintain voltage quality at designated buses, even during islanding transients. This paper concludes that presence of an electronically-interfaced DG unit makes the concept of micro-grid a technically viable option for further investigations.
1,136 citations
"Power Management Strategies for a M..." refers background in this paper
...The utility grid is expected to support the difference in real/reactive power requirements and maintain the frequency [6]....
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TL;DR: In this article, the phase tracking system of the three phase utility interface inverters is investigated in both continuous and discrete-time domains, and the optimization method is considered for the second order PLL system.
Abstract: The analysis and design of the phase-locked loop (PLL) system is presented for the phase tracking system of the three phase utility interface inverters. The dynamic behavior of the closed loop PLL system is investigated in both continuous and discrete-time domains, and the optimization method is considered for the second order PLL system. In particular, the performance of the three phase PLL system is analyzed in the distorted utility conditions such as the phase unbalancing, harmonics, and offset caused by the nonlinear load conditions and measurement errors. The tracking errors under these distorted utility conditions are also derived. The phase tracking system is implemented in a digital manner using a digital signal processor (DSP) to verify the analytic results. The design considerations for the phase tracking system are deduced from the analytic and experimental results.
1,129 citations
"Power Management Strategies for a M..." refers methods in this paper
...Input to the block is the local frequency , estimated by a conventional PLL using bus voltages [11] (see Fig....
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