Small-signal Stability Analysis of Low-inertia Power Grids with Inverter-based Resources and Synchronous Condensers: Preprint PDF Download

Author: Lizhi Ding
Publisher:
ISBN:
Category : Electric inverters
Languages : en
Pages : 0

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Author: Sayan Samanta
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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The future power grid is gradually transitioning towards a greater utilization of inverter-based resources (IBRs) to integrate renewable energy in generation portfolio. The existing synchronous generator (SG)-dominated power system is evolving into a grid, where both SGs and IBRs coexist. Since SGs are sources of mechanical inertia, their gradual replacement is resulting in a low-inertia power grid. One of the main challenges faced by such systems incorporating SGs and IBRs is the primary frequency response following a loss of generation or sudden large change in loads, which may lead to underfrequency load shedding (UFLS). Broadly, bulk power systems connected to SGs and a significant number of IBRs are the subject matter of this dissertation, with a focus on modeling, stability analysis, and control for providing frequency support from the perspective of primary frequency response. Although IBRs can be of different types depending on the control strategy, grid-forming converter (GFC) technology with a direct control over its frequency is much less understood, and is a major focus of research in this dissertation. These GFC-interfaced renewable resources in future low-inertia grids are expected to provide primary frequency support so that underfrequency load shedding is averted. The GFCs can be divided into two classes based on the control strategy: (a) class-A: droop control, dispatchable virtual oscillator control, and virtual synchronous machine, and (b) class-B: matching control. It is observed that while providing frequency support, the class-A GFCs may undergo dc-voltage collapse under current limitations during underfrequency events. On the contrary, class-B GFCs are more robust in this context. In the first part of the dissertation, we perform a stability analysis of both classes of GFCs following such events. To that end, first, the averaged phasor models of these GFC classes are developed, which can be seamlessly integrated with traditional positive sequence fundamental frequency planning models of grids. Building on this, simplified averaged models are derived to study the stability of the dc-link voltage of the GFCs under current limitations in a generic multimachine system. Using these models, the sufficiency conditions for stability for both the classes and that of instability for class-A GFCs are established. As a logical next step, a decentralized supplementary control for the droop-based class-A GFC is proposed to solve the dc-link voltage instability issue under the current limitations. This sliding mode control-based approach also aims to provide primary frequency support after the contingency. The proposed method leads to quantifiable frequency support irrespective of frequency deviation, which in turn can incentivize the plants through market participation. This approach requires the communication of frequency measurements of GFCs from adjacent buses. The proposed controller guarantees asymptotic stability of power grids with generic configurations that include multiple SGs and GFCs under dc power flow approximation and a mild assumption on the center-of-inertia based frequency dynamics model. The sliding mode controller design is challenging for a grid with multiple GFCs, as the sliding surface for each GFC requires iterative experiments for refinement. Moreover, for sliding mode control we could not establish the stability guarantee in the reduced-order system in presence of the constraints on the control input. To solve this problem, a nonlinear model predictive control (NMPC) strategy is proposed for frequency support from the GFCs, which ensures dc-link voltage stability. The NMPC approach considers a multitude of constraints including those on control input and tracks the dc-link voltage reference to indirectly regulates active power output. The controller also ensures finite-time practical stability of the close-loop system. The above-mentioned analyses and control strategies are primarily evaluated in positive sequence fundamental frequency phasor models of multiple modified IEEE benchmark systems with IBRs. Finally, the detailed electromagnetic transient (EMT) models of the IBRs are used to closely replicate the behavior of the GFCs in a real-world power grid. An EMT-TS co-simulation platform is developed for integrating the EMT models of IBRs to the phasor-based planning models of bulk power systems. This platform is used to integrate the planning model of the Western Electricity Coordinating Council (WECC) grid with an EMT-based GFC model. The proposed sliding mode control is validated in this co-simulation model to ensure the dc-link voltage stability of the GFC and provide frequency support following a contingency.

Author: Alexander Duncan Giles
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Future power systems will source much of their electrical power from converter-based generation,be it a large scale HVDC link or a smaller system such as the back-to-back converter systems found in modern, variable-speed wind turbines. This is in stark contrast to the original AC power systems which used directly-coupled synchronous generation. The transition from the past power system to the future power system will produce power systems that have both low inertia, which compromises angular and frequency stability, and low short-circuit ratios, which compromises voltage stability.In this thesis, the modelling and control of converter-based generation in low short-circuit ratio systems are investigated. For the modelling of AC power systems and the controllers being applied to the converter(s), the unified linear state-space approach is proposed. In this approach, linear state-space models of the electrical system are combined with linear state-space models in a manner which is highly scalable and sufficiently flexible to allow multiple control algorithms acting in a system instantaneously to be considered with relative ease. Three control algorithms are considered in single converter systems: dq-axis vector current control,proportional resonant control, and power synchronization control. By adopting dq-axis vector current control, the system becomes ill-conditioned at the current level, primarily due to the dynamics of the phase-locked loop, which then causes stability issues for outer feedback loops (for example DC voltage and AC voltage controllers) which accompany the current controller. Proportional resonant control, also employing a phase-locked loop, exhibits poor dynamics in the low short-circuit ratio power system. By mimicking the basic synchronization process of a synchronous generator, power synchronization control is able to perform satisfactorily in a low short-circuit ratio system, much as a synchronous generator can. Two algorithms are considered in the multi-converter, low short-circuit ratio systems: dq-axis vector current control and power synchronization control. Performance issues observed in single converter systems when dq-axis vector current control is applied are observed in the multi-converter systems. Additional sources of undesirable coupling between control loops at the current control level are observed, potentially placing more demands on the design of the outer control loops. Power synchronization control performs satisfactorily in the multi-converter systems; however, oscillatory behaviour does arise, which requires careful tuning of the controllers. In addition, it is shown that the introduction of converters using power synchronization control enables other converters (in the same system) using dq-axis vector current control to exhibit improved performance. This is due to power synchronization control causing a converter to act as an effective voltage source/regulator,and dq-axis vector current control relying on electrical proximity to a strong voltage source. This produces systems with improved conditioning, which will reduce the complexity of the design of outer controllers for dq-axis vector current controlled converters. Keywords: control, modelling, HVDC, power systems, stability, voltage-source converter, weak ACsystems, multiple-converter systems, power system planning.

Author: Adirak Kanchanaharuthai
Publisher:
ISBN:
Category :
Languages : en
Pages : 142

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The environmental and economic impact of fossil fuel generating plants has resulted in the need to find more efficient and clean sources of electricity power generation. As an alternative, promising power generation options such as renewable energy sources, especially wind energy, are receiving increased interest. This dissertation addresses some important problems in power system operations (stability and power quality) when renewable energy resources (generation and storage) are integrated into the conventional power system. In particular, the use of energy storage (STATCOM/Battery) to enhance the small-signal stability, transient stability, and voltage regulation of an electrical power system with renewable power generation is investigated as follows. 1) A linearized model of the nonlinear power system in the region of a steady-state operating point is used in conjunction with an LMI-based control design method, including D-stability, to achieve small-signal angle and frequency stability, voltage regulation, when the system is perturbed by changes in mechanical power inputs to the synchronous generators in the system. 2) A nonlinear model of the power systems with energy storage is used with an Interconnection and Damping Assignment-Passivity-Based Control design (IDA-PBC) framework to achieve transient power angle stability along with frequency and voltage regulation after the occurrence of a large disturbance (a symmetrical three-phase short circuit transmission line fault). 3) Using the combination of the IDA-PBC control law and a reduced-order nonlinear observer, voltage regulation and system stability enhancement are simultaneously accomplished following both temporary and permanent faults. To illustrate the effectiveness of the STATCOM/Battery to enhance small-signal and transient stability, the LMI-based controller design with D-stability and IDA-PBC controller design are validated using the following simulation studies: (1) a single machine infinite bus (SMIB) (2) a two-machine (synchronous generator and doubly-fed induction generator) connected to an infinite bus. For the small-signal case, simulation results show that the proposed controller can simultaneously achieve frequency and voltage regulation along with improved transient performance. For the large-signal case, the results show that the proposed controller provides improved critical clearing times (CCTs) and an enlarged domain of attraction (DOA) along with improved frequency and voltage regulation.

Author: Farhad Billimoria
Publisher:
ISBN: 9781784671600
Category :
Languages : en
Pages :

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Author: Amirnaser Yazdani
Publisher: John Wiley & Sons
ISBN: 0470551569
Category : Technology & Engineering
Languages : en
Pages : 473

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Presents Fundamentals of Modeling, Analysis, and Control of Electric Power Converters for Power System Applications Electronic (static) power conversion has gained widespread acceptance in power systems applications; electronic power converters are increasingly employed for power conversion and conditioning, compensation, and active filtering. This book presents the fundamentals for analysis and control of a specific class of high-power electronic converters—the three-phase voltage-sourced converter (VSC). Voltage-Sourced Converters in Power Systems provides a necessary and unprecedented link between the principles of operation and the applications of voltage-sourced converters. The book: Describes various functions that the VSC can perform in electric power systems Covers a wide range of applications of the VSC in electric power systems—including wind power conversion systems Adopts a systematic approach to the modeling and control design problems Illustrates the control design procedures and expected performance based on a comprehensive set of examples and digital computer time-domain simulation studies This comprehensive text presents effective techniques for mathematical modeling and control design, and helps readers understand the procedures and analysis steps. Detailed simulation case studies are included to highlight the salient points and verify the designs. Voltage-Sourced Converters in Power Systems is an ideal reference for senior undergraduate and graduate students in power engineering programs, practicing engineers who deal with grid integration and operation of distributed energy resource units, design engineers, and researchers in the area of electric power generation, transmission, distribution, and utilization.

Author: National Academies of Sciences, Engineering, and Medicine
Publisher: National Academies Press
ISBN: 0309463076
Category : Science
Languages : en
Pages : 171

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Americans' safety, productivity, comfort, and convenience depend on the reliable supply of electric power. The electric power system is a complex "cyber-physical" system composed of a network of millions of components spread out across the continent. These components are owned, operated, and regulated by thousands of different entities. Power system operators work hard to assure safe and reliable service, but large outages occasionally happen. Given the nature of the system, there is simply no way that outages can be completely avoided, no matter how much time and money is devoted to such an effort. The system's reliability and resilience can be improved but never made perfect. Thus, system owners, operators, and regulators must prioritize their investments based on potential benefits. Enhancing the Resilience of the Nation's Electricity System focuses on identifying, developing, and implementing strategies to increase the power system's resilience in the face of events that can cause large-area, long-duration outages: blackouts that extend over multiple service areas and last several days or longer. Resilience is not just about lessening the likelihood that these outages will occur. It is also about limiting the scope and impact of outages when they do occur, restoring power rapidly afterwards, and learning from these experiences to better deal with events in the future.

Author: Sofiane Bououden
Publisher: Springer Nature
ISBN: 9811564035
Category : Technology & Engineering
Languages : en
Pages : 1257

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This book gathers papers presented during the 4th International Conference on Electrical Engineering and Control Applications. It covers new control system models, troubleshooting tips and complex system requirements, such as increased speed, precision and remote capabilities. Additionally, the papers discuss not only the engineering aspects of signal processing and various practical issues in the broad field of information transmission, but also novel technologies for communication networks and modern antenna design. This book is intended for researchers, engineers and advanced postgraduate students in the fields of control and electrical engineering, computer science and signal processing, as well as mechanical and chemical engineering.

Author: R. Keith Mobley
Publisher: Elsevier
ISBN: 0080478697
Category : Technology & Engineering
Languages : en
Pages : 451

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Book Description
This second edition of An Introduction to Predictive Maintenance helps plant, process, maintenance and reliability managers and engineers to develop and implement a comprehensive maintenance management program, providing proven strategies for regularly monitoring critical process equipment and systems, predicting machine failures, and scheduling maintenance accordingly. Since the publication of the first edition in 1990, there have been many changes in both technology and methodology, including financial implications, the role of a maintenance organization, predictive maintenance techniques, various analyses, and maintenance of the program itself. This revision includes a complete update of the applicable chapters from the first edition as well as six additional chapters outlining the most recent information available. Having already been implemented and maintained successfully in hundreds of manufacturing and process plants worldwide, the practices detailed in this second edition of An Introduction to Predictive Maintenance will save plants and corporations, as well as U.S. industry as a whole, billions of dollars by minimizing unexpected equipment failures and its resultant high maintenance cost while increasing productivity. - A comprehensive introduction to a system of monitoring critical industrial equipment - Optimize the availability of process machinery and greatly reduce the cost of maintenance - Provides the means to improve product quality, productivity and profitability of manufacturing and production plants

Author: Clark W. Gellings
Publisher: CRC Press
ISBN: 1000355314
Category : Business & Economics
Languages : en
Pages : 182

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The power system has often been cited as the greatest and most complex machine ever built, yet it is predominantly a mechanical system. Technologies and intelligent systems are now available that can significantly enhance the overall functionality of power distribution and make it ready to meet the needs of the 21st century. This book explains how sensors, communications technologies, computational ability, control, and feedback mechanisms can be effectively combined to create this new, continually adjusting "smart grid" system. It provides an understanding of both IntelliGridSM architecture and EnergyPortSM as well as how to integrate intelligent systems to achieve the goals of reliability, cost containment, energy efficiency in power production and delivery, and end-use energy efficiency.