Small Signal Stability Analysis Of Low Inertia Power Grids With Inverter Based Resources And Synchronous Condensers Preprint
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Small Signal Stability Analysis Of Low Inertia Power Grids With Inverter Based Resources And Synchronous Condensers Preprint
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Author : Lizhi Ding
language : en
Publisher:
Release Date : 2021
Small Signal Stability Analysis Of Low Inertia Power Grids With Inverter Based Resources And Synchronous Condensers Preprint written by Lizhi Ding and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021 with Electric inverters categories.
Comparative Small Signal Stability Analysis Of Grid Forming And Grid Following Inverters In Low Inertia Power Systems
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Author : Lizhi Ding
language : en
Publisher:
Release Date : 2022
Comparative Small Signal Stability Analysis Of Grid Forming And Grid Following Inverters In Low Inertia Power Systems written by Lizhi Ding and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with Electric inverters categories.
Impact Of Increased Inverter Penetration On Power System Small Signal Stability
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Author : Yashen Lin
language : en
Publisher:
Release Date : 2021
Impact Of Increased Inverter Penetration On Power System Small Signal Stability written by Yashen Lin and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021 with Electric inverters categories.
Frequency Stability In Low Inertia Power Systems
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Author : Atinuke Abolaji Ademola-Idowu
language : en
Publisher:
Release Date : 2020
Frequency Stability In Low Inertia Power Systems written by Atinuke Abolaji Ademola-Idowu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
The increased penetration of renewable energy resources particularly those connected via inverters to the electric grid like wind and solar, has resulted in the displacement of traditional synchronous generators. This has subsequently led to a decline in the available rotational inertia from these synchronous generators that provides immediate frequency response in the event of a disturbance to the grid. The result is a larger increase in the frequency deviation, rate of change of frequency, and a slower settling time, all of which can lead to frequency instability and an eventual collapse of the grid. This network condition has been termed low-inertia power systems. The aim of this dissertation is to design control and optimization algorithms that will enable these inverter-based resources participate effectively and optimally in providing frequency control response in a low-inertia power systems by controlling their inverter interfaces. The first part of this dissertation focuses on optimizing the performance of the popular virtual synchronous machine control structure for inverter-based resources, by developing an algorithm to optimally design the inertia and damping gain coefficient of its frequency control loop. This enables these inverter-based resources to participate efficiently in the inertia response portion of primary frequency control, by producing active power proportional to frequency measurements, in response to a power imbalance or disturbance to the grid, just like a synchronous generator. The second part of this dissertation focuses on designing a novel inverter-based resource control strategy termed inverter power control, which is based on model predictive control, to directly determine the optimal active-power set-point for the inverter-based resources in the event of a power imbalance or disturbance in the system. This proposed control framework alleviates a fundamental drawback of the virtual synchronous machine approach that constrains the inverter-based resources to behave like synchronous machines when responding to a frequency event thereby limiting the potentials of these fast acting and flexible inverter-based resources.
Small Signal Stability Support From Dynamically Configurable Grid Forming Following Inverters For Distribution Systems Preprint
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Author :
language : en
Publisher:
Release Date : 2022
Small Signal Stability Support From Dynamically Configurable Grid Forming Following Inverters For Distribution Systems Preprint written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with categories.
The growth of inverter-based resources (IBRs) in modern power systems can challenge system stability since they do not natively provide inertia, prompting a need to develop new methods to address the potential instabilities. In this paper, a dynamically configurable grid-forming (GFM) and grid-following (GFL) control is proposed, which enables inverters to flexibly transition to support system needs. The operation mode transition between GFM and GFL controls is adopted as an additional degree of control flexibility to adjust the small-signal stability margin. In addition, a holistic and detailed small-signal model for a distribution feeder that captures the dynamics from both synchronous generators (SGs) and IBRs is also derived and used to evaluate the effectiveness of the proposed GFM/GFL controls to augment the system small-signal stability margin. Case studies with varying levels of IBRs were implemented in MATLAB/Simulink to demonstrate the effectiveness of the proposed approach.
Modeling And Stability Analysis Of Inverter Based Resources
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Author : Lingling Fan
language : en
Publisher:
Release Date : 2024
Modeling And Stability Analysis Of Inverter Based Resources written by Lingling Fan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2024 with Electric inverters categories.
Modeling And Control Of Grids Of Near Future With Converters And Synchronous Machines
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Author : Sayan Samanta
language : en
Publisher:
Release Date : 2023
Modeling And Control Of Grids Of Near Future With Converters And Synchronous Machines written by Sayan Samanta and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023 with categories.
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.
A Study Of Small Signal Stability In Power Systems With Converters
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Author : Alexander Duncan Giles
language : en
Publisher:
Release Date : 2018
A Study Of Small Signal Stability In Power Systems With Converters written by Alexander Duncan Giles and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with categories.
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.
Study Of Inverter Control Strategies On The Stability Of Low Inertia Microgrid Systems Preprint
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Author :
language : en
Publisher:
Release Date : 2022
Study Of Inverter Control Strategies On The Stability Of Low Inertia Microgrid Systems Preprint written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with categories.
This paper investigates the stability of low-inertia microgrid systems with two control strategies that have different percentages of grid-forming (GFM) inverters. The first control strategy has approximately 50% GFM inverters, and all the battery inverters are working in GFM control mode. Originally, the second control strategy has approximately 10% GFM inverters, with only two battery inverters working in GFM control mode and the rest working in grid-following (GFL) PQ control mode based on current control, which cannot stabilize the microgrid system. Then, the second control strategy is modified to change the GFM inverters from droop control to isochronous control and the GFL battery inverters from traditional current control to voltage control for power control. Both control strategies can maintain system stability; however, the first control strategy can better handle contingency events. The study indicates that 1) a microgrid system with a higher percentage of GFM inverters has better stability; and 2) a microgrid with a lower percentage of GFM inverters can have poor stability, but improved control strategies in inverters can improve system stability. This study improves the understanding of how different percentages of GFM inverters and inverter control strategies affect the system stability of low-inertia microgrids.
Impact Of Inverter Interfaced Renewable Generation On Transient Stability At Varying Levels Of Penetration Preprint
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Author :
language : en
Publisher:
Release Date : 2019
Impact Of Inverter Interfaced Renewable Generation On Transient Stability At Varying Levels Of Penetration Preprint written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
The transient dynamics of conventional power systems are dominated by synchronous generators, and low-inertia inverters serve as the primary interface between power systems and renewable energy resources. Increasing penetration levels of inverter-interfaced generation are impacting the transient dynamics of power systems. In this paper, we attempt to quantify these impacts at different penetration levels. An elementary system including one inverter, one synchronous generator, and one load is studied under different parameter variations to assess the transient dynamics of the system. To quantify transient stability, the post-fault regions of attraction of the system are estimated by the sample-based basin stability approach with parallel computing technology. The simulation results suggest that different inverter penetration levels, inertias of the generator, inverter controller gains, and phase-locked loop controller gains have a clear impact on the regions of attraction as well as on the transient dynamics of proposed systems.