Modeling And Control Of Modular Multilevel Converter Based On Ordinary Differential Equations And Its Applications For Hvdc System
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Modeling And Control Of Modular Multilevel Converter Based On Ordinary Differential Equations And Its Applications For Hvdc System
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Author : Haihao Jiang
language : en
Publisher:
Release Date : 2020
Modeling And Control Of Modular Multilevel Converter Based On Ordinary Differential Equations And Its Applications For Hvdc System written by Haihao Jiang 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.
"High-voltage direct current (HVDC) system is more efficient than high-voltage alternating current (HVAC) system for long-distance, bulk power transmission. Modularity, flexibility, reliability and high efficiency make the modular multilevel converter (MMC) the topology of choice in HVDC applications. Because the increasing number of installations shows that the MMC-HVDC is the HVDC of the future, this thesis is continuing research to advance the capability of the MMC-HVDC. This thesis focuses on fast simulation capability and control strategies for the MMC-HVDC. The main objectives are: (1) to develop a fast and accurate simulation model of a single MMC station and models of multi-terminal MMC-HVDC stations (MTDC-MMC); (2) to investigate the method to design proper parameters for high damping; (3) to design the MMC-HVDC with the capability of power oscillation damping (POD). Simulation is computation-intensive in MMC. The thesis develops a fast and accurate method by which an MMC station is modeled by ordinary differential equations (ODE). The proposed MMC ODE model is implemented in MATLAB SIMULINK and its correctness is validated by the MMC Detail Equivalent Model (DEM) in RT-LAB. Taking advantage of its speed and accuracy, a Four-Terminal MMC-HVDC system based on the MMC ODE model is developed. The ODE model meets the speed and accuracy requirements of power systems engineers who are concerned with planning, operation and protection studies. As the ordinary differential equations are nonlinear, small perturbation about a steady-state is applied to obtain the linearized time-periodic matrix. The steady-state takes a long time to simulate because it depends on the transients to have all damped out. The method of Aprille and Trick is applied. Simulation converges to the steady-state in one cycle of 50 Hz. The resultant linearized matrix is time-periodic. The Floquet-Lyapunov Theorem is applied to construct the state-transition matrix from the linearized time-periodic matrix. The eigenvalues of the state-transition matrix contain the coefficients of damping. Graphs of damping coefficients plotted against different sizes of circuit parameters are displayed to assist designers in realizing high damping. The thesis looks for opportunities to add value to the MMC-HVDC. The active power transmissibility of AC transmission lines is limited by the transient stability limit which is significantly below the thermal limit. Extensive research and development have been pursued to increase the transient stability limit by flexible AC transmissions system (FACTS). This thesis seeks to use the MMC-HVDC to operate as power oscillation damper to increase the power transmissibility. The thesis looks for opportunities to integrate previously proven control methods into a common universal control. The Universal Controller brings together the deadbeat control, the circulating current suppression control (CCSC), the POD and the decoupled P-Q strategy in the control of the MMC-HVDC station by the MMC ODE model. Deadbeat control enables the MMC to survive destructively large AC fault currents to improve the transient stability of AC grids"--
Modular Multilevel Converters
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Author : Sixing Du
language : en
Publisher: John Wiley & Sons
Release Date : 2018-02-22
Modular Multilevel Converters written by Sixing Du and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-02-22 with Science categories.
An invaluable academic reference for the area of high-power converters, covering all the latest developments in the field High-power multilevel converters are well known in industry and academia as one of the preferred choices for efficient power conversion. Over the past decade, several power converters have been developed and commercialized in the form of standard and customized products that power a wide range of industrial applications. Currently, the modular multilevel converter is a fast-growing technology and has received wide acceptance from both industry and academia. Providing adequate technical background for graduate- and undergraduate-level teaching, this book includes a comprehensive analysis of the conventional and advanced modular multilevel converters employed in motor drives, HVDC systems, and power quality improvement. Modular Multilevel Converters: Analysis, Control, and Applications provides an overview of high-power converters, reference frame theory, classical control methods, pulse width modulation schemes, advanced model predictive control methods, modeling of ac drives, advanced drive control schemes, modeling and control of HVDC systems, active and reactive power control, power quality problems, reactive power, harmonics and unbalance compensation, modeling and control of static synchronous compensators (STATCOM) and unified power quality compensators. Furthermore, this book: Explores technical challenges, modeling, and control of various modular multilevel converters in a wide range of applications such as transformer and transformerless motor drives, high voltage direct current transmission systems, and power quality improvement Reflects the latest developments in high-power converters in medium-voltage motor drive systems Offers design guidance with tables, charts graphs, and MATLAB simulations Modular Multilevel Converters: Analysis, Control, and Applications is a valuable reference book for academic researchers, practicing engineers, and other professionals in the field of high power converters. It also serves well as a textbook for graduate-level students.
Dynamics And Control Of Switched Electronic Systems
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Author : Francesco Vasca
language : en
Publisher: Springer Science & Business Media
Release Date : 2012-03-28
Dynamics And Control Of Switched Electronic Systems written by Francesco Vasca and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-03-28 with Technology & Engineering categories.
The increased efficiency and quality constraints imposed on electrical energy systems have inspired a renewed research interest in the study of formal approaches to the analysis and control of power electronics converters. Switched systems represent a useful framework for modeling these converters and the peculiarities of their operating conditions and control goals justify the specific classification of “switched electronic systems”. Indeed, idealized switched models of power converters introduce problems not commonly encountered when analyzing generic switched models or non-switched electrical networks. In that sense the analysis of switched electronic systems represents a source for new ideas and benchmarks for switched and hybrid systems generally. Dynamics and Control of Switched Electronic Systems draws on the expertise of an international group of expert contributors to give an overview of recent advances in the modeling, simulation and control of switched electronic systems. The reader is provided with a well-organized source of references and a mathematically-based report of the state of the art in analysis and design techniques for switched power converters. Intuitive language, realistic illustrative examples and numerical simulations help the reader to come to grips with the rigorous presentation of many promising directions of research such as: converter topologies and modulation techniques; continuous-time, discrete-time and hybrid models; modern control strategies for power converters; and challenges in numerical simulation. The guidance and information imparted in this text will be appreciated by engineers, and applied mathematicians working on system and circuit theory, control systems development, and electronic and energy conversion systems design.
Efficient Modeling Of Modular Multilevel Hvdc Converters Mmc On Electromagnetic Transient Simulation Programs
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Author : Udana Gnanarathna
language : en
Publisher:
Release Date : 2014
Efficient Modeling Of Modular Multilevel Hvdc Converters Mmc On Electromagnetic Transient Simulation Programs written by Udana Gnanarathna and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
The recent introduction of a new converter topology, the modular multilevel converter (MMC) is a major step forward in voltage sourced converter (VSC) technology for high voltage, high power applications. To obtain a multilevel ac output waveform, a large number of semiconductor switches has to be used in the converter. The number of switches in the MMC for HVDC transmission is typically two orders of magnitudes larger than that in a two or three level VSC used in earlier generation. This large device count creates a computational challenge for electromagnetic transients (EMT) simulation programs, as it significantly increases the simulation time. The purpose of this research is to investigate whether the simulation can be speeded up. This research develops an efficient, time-varying Thévenin's equivalent model for the MMC converter based on partitioning the system's admittance matrix. EMT simulation results show that the proposed equivalent model can drastically reduce the computational time without loss of accuracy. The use of the proposed equivalent method is demonstrated by simulating a point to point MMC based HVDC transmission system successfully with more than 100 levels. This approach enables what was hitherto not practical; the modeling of large MMC based HVDC systems on personal computers. With the assumption of ideal switch operation and using an equivalent average capacitor value based approach, an average valued model of MMC is also proposed in this thesis. The average model can be accurately used in most of the system level studies. The control algorithms and other modeling aspects of MMC applications are also presented in this thesis. One of the advantages of multilevel converters is the low operating losses as the smaller switching frequency of each individual power electronics switch and the low voltage step change during each switching. Using a recently developed, time domain simulation approach, the operating losses of the MMC converter are estimated in this thesis. When comparing the MMC operating losses against the losses of two-level VSC, the power loss for the two-level VSC is found to be significantly higher than the power loss of the MMC.
Design Control And Application Of Modular Multilevel Converters For Hvdc Transmission Systems
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Author : Kamran Sharifabadi
language : en
Publisher: John Wiley & Sons
Release Date : 2016-08-22
Design Control And Application Of Modular Multilevel Converters For Hvdc Transmission Systems written by Kamran Sharifabadi and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-08-22 with Science categories.
Design, Control and Application of Modular Multilevel Converters for HVDC Transmission Systems is a comprehensive guide to semiconductor technologies applicable for MMC design, component sizing control, modulation, and application of the MMC technology for HVDC transmission. Separated into three distinct parts, the first offers an overview of MMC technology, including information on converter component sizing, Control and Communication, Protection and Fault Management, and Generic Modelling and Simulation. The second covers the applications of MMC in offshore WPP, including planning, technical and economic requirements and optimization options, fault management, dynamic and transient stability. Finally, the third chapter explores the applications of MMC in HVDC transmission and Multi Terminal configurations, including Supergrids. Key features: Unique coverage of the offshore application and optimization of MMC-HVDC schemes for the export of offshore wind energy to the mainland. Comprehensive explanation of MMC application in HVDC and MTDC transmission technology. Detailed description of MMC components, control and modulation, different modeling approaches, converter dynamics under steady-state and fault contingencies including application and housing of MMC in HVDC schemes for onshore and offshore. Analysis of DC fault detection and protection technologies, system studies required for the integration of HVDC terminals to offshore wind power plants, and commissioning procedures for onshore and offshore HVDC terminals. A set of self-explanatory simulation models for HVDC test cases is available to download from the companion website. This book provides essential reading for graduate students and researchers, as well as field engineers and professionals who require an in-depth understanding of MMC technology.
Modular Multilevel Converters With Multi Frequency Power Transfer
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Author : Yuan Li
language : en
Publisher:
Release Date : 2022
Modular Multilevel Converters With Multi Frequency Power Transfer written by Yuan Li 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 power transmission categories.
The MMC is the dominant voltage-sourced converter technology for HVDC systems including terrestrial power transmission and offshore wind power integration. It is also a state-of-the-art solution for emerging MVDC applications such as bipolar dc distribution and grid integration of renewable energy resources. Significant research has been recently targeting the development of new MMC-based topologies that can reap the benefits of the conventional dc-ac MMC in dc grids and hybrid ac/dc power systems. Notable examples include dc-dc converters, multi-port converters, line power flow controllers and power tapping stations. This thesis introduces the concept of multi-frequency power transfer in MMCs where the magnetics windings are multi-tasked to carry currents with multiple frequency components, namely dc and fundamental frequency. Core dc flux cancellation is imposed by appropriate orientation of the individual windings. This novel power transfer mechanism can eliminate redundant energy conversion through partial-power-processing while offering increased flexibility in converter port power flows. Based on the multi-frequency power transfer concept, new MMC-based topologies are proposed that are well suited for MVDC and HVDC grids and hybrid ac/dc systems. Firstly, a new class of single-stage modular multilevel dc-dc converter, termed the M2DC-CT, is proposed for applications requiring either high or low dc stepping ratios. By placing center-tapped transformer windings in series with the arms in each phase leg, the advantages of minimized ac arm currents and absence of dc voltage stress between windings are simultaneously obtained unlike in prior art. Modeling and analysis gives insight into the M2DC-CT multi-frequency power transfer characteristics and suitable converter controls are developed. Converter operation is validated through simulation and experiment. %The M2DC-CT is further extended into a three-port converter by addition of a grid side transformer winding. Secondly, a dual MMC structure is presented that achieves multi-frequency power transfer by tying together the three mid-points of the converter-side center-tapped transformer windings to form an additional dc port. This creates a bipolar MMC with the ability to balance the dc pole power flows in bipolar dc grids. The employed center-tapped transformer has a Volt-Ampere rating that is the same as a conventional grid interfacing transformer. Dynamic controls formulated in the $\alpha\beta$-frame provide tight regulation of the port power flows while ensuring balanced capacitor voltages. The independent pole balancing capability is confirmed through simulation of detailed MVDC-level and HVDC-level PSCAD models and rigorous experimental testing on a scaled-down laboratory prototype. Thirdly, the aforementioned multi-frequency dual MMC structure is proposed for use as a three-port MMC. It allows simultaneous dc-dc and dc-ac conversions between an ac grid and two dc systems, which is distinctly different from the earlier bipolar dc grid application. The $\alpha\beta$ controls developed earlier are easily extended for the three-port application by assigning appropriate reference signals. Steady-state and dynamic operation of the three-port dual MMC topology is validated by simulation with a HVDC-level PSCAD model and extensive experimental tests. Lastly, a detailed comparative assessment of three-port MMCs for high-power applications is conducted. The proposed three-port dual MMC structure and three-port version of the M2DC-CT are compared against two other existing three-port MMCs, on the basis of efficiency, semiconductor effort, internal energy storage and magnetics. Both MVDC and HVDC case studies are examined including several different power flow cases, with provisions for fault blocking. The results indicate the use of multi-frequency power transfer can enable significant reductions in converter operating losses and cost relative to prior art, depending on the application.
Modeling And Control Of Modular Multilevel Converters
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Author : Su Zhang
language : en
Publisher:
Release Date : 2020
Modeling And Control Of Modular Multilevel Converters written by Su Zhang 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 investigation of improved semiconductor devices, power converter topologies and modulation schemes is essential for the development of advanced power electronics technology. As a preferred option of power conversion for high-power applications, multilevel converters, especially Modular Multilevel Converters (MMCs), are gaining increasing popularity in both industry and academia. However, there are several technical challenges associated with the MMC topology. One of the main challenges is the minimization of voltage variations in module capacitors. In addition, the circulating currents, which originate from both the capacitor voltage variations and switching scheme, increase the rating of power devices and power losses. Typically, cascaded control schemes, based on Proportional-Integral (PI) controllers and Pulse Width Modulators (PWMs), have predominately been used to control MMCs. However, tuning of multiple PI loops is difficult and also influences the performance of MMC at both steady-state and transient operating conditions. To overcome these drawbacks, this thesis proposes a Model Predictive Direct Slope Control (MPDSC) scheme for MMCs. This scheme is capable of handling multiple control objectives without using a modulator, thus significantly simplifies the complexity of the control scheme. In addition, a long prediction horizon can be generated without increasing the computational burden of the control algorithm, and therefore the performance of the MMC could be further improved with a shorter sampling time. The viability of MPDSC is demonstrated using simulated and experimental results of a 380-VA prototype MMC, as well as benchmarking against the performance of a prototype controlled by Model Predictive Direct Current Control (MPDCC) scheme. The MPDSC offers performance that is comparable to MPDCC, but with significantly reduced complexity and computational burden. However, this scheme considers all possible switching states to evaluate each control variable, this invariably making the computational burden still heavy. In addition to this, the tuning of multiple weighting factors is cumbersome and inefficient. To overcome these drawbacks, this thesis proposes a Hierarchical Model Predictive Control (HMPC) scheme for MMCs. With this scheme, the load currents are regulated within symmetrical bounds using a modified MPDSC, and the capacitor voltages, circulating currents and switching frequency are minimized through a Model Predictive Multilayer Control (MPMC) scheme. To reduce computational burden of the control algorithm, HMPC evaluates each control variable independently while minimizing the number of switching states for evaluation. Instead of using conventional weighting factors, HMPC utilizes the number of switching states of lower costs as a tuning factor for each control variable, which makes the tuning process efficient and adaptable to any operating conditions. A comparison with a conventional Finite Control Set Model Predictive Control (FCS-MPC) scheme, using simulated as well as experimental results of a prototype MMC, reveals that HMPC offers superior performance. With MPDSC and HMPC schemes, the capacitor voltage variations of MMCs can only be reduced to a certain level. Therefore, this thesis presents a modified MMC topology that utilizes an Inductive Power Transfer (IPT) system to maintain the capacitor voltages within tight bounds. This topology simplifies the control of capacitor voltages, irrespective of the switching scheme and operating conditions of the converter. A mathematical model of the modified topology is developed, and a control scheme is also proposed. The feasibility of the control scheme and the accuracy of the mathematical model are validated using simulated as well as theoretical results of a 2-kVA MMC-IPT system.
Design Analysis And Operation Of Hybrid Modular Multilevel Converters For Hvdc Applications
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Author : Zeng Rong
language : en
Publisher:
Release Date : 2015
Design Analysis And Operation Of Hybrid Modular Multilevel Converters For Hvdc Applications written by Zeng Rong and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
This thesis investigates the design, analysis, and operation of modular multilevel converters (MMC) for HVDC applications. Based on the operation principles of the MMC, the operation of MMC under asymmetrical arm impedance conditions is analysed using three equivalent sub-circuits at different freqeuncy. Detail analysis of the impact of asymmetrical conditions on the differential-mode current, the common-mode current and sub-module (SM) capacitor voltages, is performed. Based on the analysis, the corresponding control targets and an improved control strategy are designed to improve the operation performance. Considering the advantages of half-bridge based SM (HBSM) and full-bridge based SM (FBSM), a hybrid MMC (H-MMC) configuration consisting of FBSMs and HBSMs is proposed. By adopting the negative voltage state for some of the FBSMs, the output voltage range is extended to increase converter power transmission capability. By considering the relationships between the AC and DC voltages, AC, DC and arm currents, the ratio of the numbers of the FBSM to HBSM is analysed in order to maintain capacitor voltage balance and retain DC fault blocking capability. An equivalent circuit for the H-MMC is proposed, which considers each arm to be consisted of two individual voltage sources. This model is used to analyse SM capacitor voltage balancing and ripple. A two-stage selection and sorting algorithm is developed to ensure capacitor voltage balancing among the SMs. The proposed H-MMC is compared to other topologies in terms of power device utilization and power losses, and it shows that the H-MMC has higher device utilization and lower power loss than the conventional FBSM based MMC; Furthermore, The DC fault ride-through capability of the H-MMC are discussed. It is found that the H-MMC can not only isolate the DC fault, but also coniture operating at a wide DC voltage range from zero to rated value. Such two features of the H-MMC show the advantages in the hybrid configurations over the conventional FBSM and HBSM systems. Finally, two applications based on the proposed H-MMC are presented; one is a high power DC/DC converter with fault blocking capability for interconnecting large HVDC systems, and the other is a hybrid HVDC transmission system comprising a wind farm side VSC based on the H-MMC and a grid side LCC for transmitting wind power to AC grid.
Voltage Sourced Converters In Power Systems
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Author : Amirnaser Yazdani
language : en
Publisher: John Wiley & Sons
Release Date : 2010-03-25
Voltage Sourced Converters In Power Systems written by Amirnaser Yazdani and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010-03-25 with Technology & Engineering categories.
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.
Parallel Dynamic And Transient Simulation Of Large Scale Power Systems
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Author : Venkata Dinavahi
language : en
Publisher: Springer Nature
Release Date : 2022-01-01
Parallel Dynamic And Transient Simulation Of Large Scale Power Systems written by Venkata Dinavahi and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022-01-01 with Technology & Engineering categories.
This textbook introduces methods of accelerating transient stability (dynamic) simulation and electromagnetic transient simulation on massively parallel processors for large-scale AC-DC grids – two of the most common and computationally onerous studies done by energy control centers and research laboratories for the planning, design, and operation of such integrated grids for ensuring the security and reliability of electric power. Simulation case studies provided in the book range from small didactic test circuits to realistic-sized AC-DC grids, and special emphasis is placed on detailed device-level multi-physics models for power system equipment and decomposition techniques for simulating large-scale systems. Parallel Dynamic and Transient Simulation of Large-Scale Power Systems: A High Performance Computing Solution is a comprehensive state-of-the-art guide for upper-level undergraduate and graduate students in power systems engineering. Practicing engineers, software developers, and scientists working in the power and energy industry will find it to be a timely and valuable reference for solving potential problems in their design and development activities. Detailed device-level electro-thermal modeling for power electronic systems in DC grids; Provides comprehensive dynamic and transient simulation of integrated large-scale AC-DC grids; Offers detailed models of renewable energy system models.