On the Stability of Power Electronics-Dominated Systems: Challenges and Potential Solutions

Guest Editorial: Situational awareness of integrated energy systems

This paper presents how power electronics concepts are utilized to teach the topics in power system analysis course. Power system analysis is one of the multiple core courses on power engineering in almost all Electrical Engineering programs around the world. At Grand Valley State University, it is the only course in power engineering offered to Electrical Engineering students during a twelve-week summer semester in junior year. This course covers the fundamental concepts and their applications in all three sections of a complex power system namely generation, transmission, and distribution systems. In recent years, there has been a significant change in the role and application of power electronics in modern power systems. However, at GVSU power electronics is a graduate course and it is also taken by some senior students with deep interest in it as an elective. Hence, attempts have been made to get all Electrical Engineering students, not only the willing seniors, introduced to power electronics and its applications in all three sections of a power system. These include teaching some power system concepts with applications of power electronics and administering power converter based course projects. This paper presents the design of the course to implement power electronics concepts and the implementation of course projects in power system analysis course. The pedagogical challenge is to enhance students' learning of modern power system. This paper shows how it enhanced and changed students' perception about the scope of power engineering.

Modern power system is a typical cyber-physical system (CPS). The stable operation of the modern power system relies increasingly on the well-functioning cyber system. Therefore, it is important to include the possible effects of the cyber system as we assess power system stability. Since our main purpose of considering the cyber system is to study its possible effect on power system operation, and cyber system mainly affect the physical system through affecting the information flow, we mainly focus on the information flow as we model the cyber system. In the proposed model, the details in cyber system operation is not considered to reduce redundant calculation burden. Instead, cyber elements and cyber contingencies are classified and modeled based on their effect on the information flow, reflecting their possible effect on the operation of the power system. We can simulate the CPS by integrating the proposed cyber system model with the power system model and conducting mixed simulation. Case study is carried out in the AVC system in the IEEE-14 bus power system. The result shows the proposed cyber system model and CPS simulation method can be used to analysis the possible effect of cyber contingencies on the power system.

The application of unified power flow controller (UPFC) has become an inevitable trend to deal with challenges faced by modern power system such as optimization of power supply and system operation. However, review researches on UPFC are less while the researches on specific technologies mostly focus on theoretical fields, which are difficult to guide actual engineering. To this end, this paper discusses several key issues of UPFC in its actual application. First of all, technical process of UPFC in actual application was proposed and its six key issues were pointed out. Then, for three issues in the process of “scheme-obtaining of UPFC application”, the principles of necessity to configure UPFC, the method of determining UPFC location and capacity, the method of determining UPFC control strategy are discussed. Finally, for three issues in the process of “influence analysis and optimization for UPFC”, simulation calculation method of power system with UPFC, influences of UPFC on power system operation, changes strategy of operating parameter for UPFC are discussed. The work done in this article aims to provide a reference for the actual application of UPFC.

Model-based network-wide optimizations in real-time emergency control of power systems are largely bottlenecked by the fast computational requirements. Furthermore, the operational aspects of modern power and energy systems are going through transformative changes to tackle global renewable energy expansion-related issues. Decentralized operations in power systems are becoming essential with the influx of distributed energy resources (DERs), dynamic loads, and electric vehicles (EVs). This research considers a well-known model-based strategy, Model Predictive Control (MPC), for real-time operation and controls of power systems and proposes novel methods utilizing machine learning, data-driven methods, and operator theory to solve computational challenges by making those real-time for the first time. Additionally, we develop a distributed MPC framework to address the recent needs of power systems' operation and control. In Part I, we first present a machine learning (ML)-accelerated MPC implementation in emergency voltage control problems. This method computes an optimal control strategy for the nominal system model offline and performs successive online control corrections at each control instant to adapt the offline computed controls for real-time scenarios. In the online phase, the required voltage trajectory prediction and its sensitivity computation to control inputs are achieved by machine learning-based approaches, thereby accelerating the overall control computation multiple times. Next, we present an alternative data-learned linear Koopman embedding approach for model predictive emergency voltage control in a power grid. This approach involves a "basis-dictionary free" method to lift the nonlinear power system dynamics to a higher dimensional linear space where MPC is exercised in a real-time fashion. We propose a novel data-driven encoder-decoder architecture, Koopman-inspired deep neural network (KDNN), which supports end-to-end learning from trajectory data. The MPC optimization in linear space makes the problem scalable and rapid for real-time implementations. Part II of this research focuses on distributed MPC design for quasi-static power flow-based voltage control problems under short-term (15-minute) variations of load and generation profiles. To realize the proposed distributed control, first, a centralized voltage control problem assuming grid observability is formulated and next transferred to the distributed versions based on both bus-wise and area-wise decomposition of the network. Distributed versions are solved via the alternating direction method of multipliers (ADMM), utilizing only neighbor-to-neighbor communications to attain optimal solutions. The implementation, efficacy, performance, and robustness of proposed research approaches are validated with IEEE test system benchmarks.

Voltage source converters (VSCs) have emerged as the key components in modern power systems, facilitating efficient energy conversion and flexible power flow control. Understanding the fundamental circuit model of VSCs is essential for their accurate modeling and analysis in power system studies. A basic voltage source converter circuit model connected to an LC filter is essential because it lowers the harmonic distortions and enhances the overall power quality of the micro-grid. This guarantees a clean and steady power supply, which is necessary for the integration of multiple renewable energy sources and sensitive loads. A comprehensive methodology for developing a basic circuit model of VSCs, focusing on the key components and principals involved, is presented in this paper. The methodology includes the modeling of space vector pulse-width modulation (SVPWM) as well as the direct quadrature zero synchronous reference frame. Different design controls, including the design of current control loop in the S-domain, the design of the direct current (DC) bus voltage control loop in the S-domain, and the design of the alternating current (AC) voltage control loop in the S-domain, are explored to capture the dynamic behavior and control strategies of VSCs accurately. The proposed methodology provides a systematic framework for modeling VSCs, enabling engineers and researchers to analyze their performance and assess their impact on power system stability and operation. Future studies can be conducted by using case studies and simulation scenarios to show the efficiency and applicability of the developed models in analyzing VSC-based power electronics applications, including high-voltage direct current (HVDC) transmission systems and flexible alternating current transmission systems (FACTS). The significance of this work lies in its potential to advance the understanding and application of VSCs, contributing to more resilient and efficient power systems. By providing a solid foundation for future research and development, this study supports the ongoing integration of renewable energy sources and the advancement of modern electrical infrastructure.

As power systems grow in their size and interconnections, their complexity increases. Rising costs due to inflation and increased environmental concerns has made transmission, as well as generation systems be operated closer to design limits. Hence power system voltage stability and voltage control are emerging as major problems in the day-to-day operation of stressed power systems. For secure operation and control of power systems under normal and contingency conditions it is essential to provide solutions in real time to the operator in energy control center (ECC). Artificial neural networks (ANN) are emerging as an artificial intelligence tool, which give fast, though approximate, but acceptable solutions in real time as they mostly use the parallel processing technique for computation. The solutions thus obtained can be used as a guide by the operator in ECC for power system control. This paper deals with development of an ANN architecture, which provide solutions for monitoring, and control of voltage stability in the day-to-day operation of power systems.

As the use of wind power turbines increases worldwide, there is a rising interest on their impacts on power system operation and control. Frequency regulation in interconnected networks is one of the main challenges posed by wind turbines in modern power systems. The wind power fluctuation negatively contributes to the power imbalance and frequency deviation. Significant interconnection frequency deviations can cause under/over frequency relaying and disconnect some loads and generations. Under unfavorable conditions, this may result in a cascading failure and system collapse.This chapter presents an overview of the key issues on frequency regulation concerning the integration of wind power units into the power systems. Following a brief survey on the recent developments, the impact of power fluctuation produced by wind units on system frequency performance is presented. An updated frequency response model is introduced, and the inertia contribution of wind turbine in the overall system inertia is properly considered. The need for the revising of frequency performance standards is emphasized, and an intelligent agent based load frequency control (LFC), using multi-agent reinforcement learning (MARL) is proposed. Finally, nonlinear time-domain simulations on a 39-bus test power system are used to demonstrate the capability of the proposed control structure, and to analyze the system frequency performance in the presence of high wind power penetration and associated issues.KeywordsPower SystemWind TurbineWind PowerWind FarmProportional IntegralThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

This paper proposes a predictive techno-economic analysis in terms of voltage stability and cost using regression-based machine learning (ML) models and effectiveness of the analysis is validated. Predictive analysis of a power system is proposed to address the need for faster and accurate analyses that would aid in the operation and control of modern power system. Several methods of analyses including metaheuristic optimization algorithms, artificial intelligence techniques and machine learning algorithms are being developed and used. Predictive ML models for two modified IEEE 14-bus and IEEE-30 bus systems, integrated with renewable energy sources (solar and wind) and reactive power compensative device (STATCOM) are proposed and developed with features that include hour of the day, solar irradiation, wind velocity, dynamic grid price and system load. An hour-wise input database for the model development is generated from monthly average data and hour-wise daily curves with normally distributed standard deviations. The data feasibility tests and output database generation is performed using MATLAB. Linear and higher order polynomial regression models are developed for the 8760hr database using Python 3.0 in JupyterLab and a best-fit predictive ML model is identified by analysing the coefficients of determination. The voltage stability and cost predictive ML models were tested for a 24hr input profile. The results obtained and the comparison with the expected values are furnished. Prediction of the outputs for the test data validate the accuracy of the developed model.

A thorough and exhaustive presentation of theoretical analysis and practical techniques for the small-signal analysis and control of large modern electric power systems as well as an assessment of their stability and damping performance.

To ensure stable operation of a power system, it is necessary to analyse the power system performance under various operating conditions. Analysis includes studies such as power flow and both steady-state and transient stability. To perform such studies requires knowledge about the models used to represent the various components that constitute an integrated power system. In situations where there is a risk of loss of stability, it is necessary to apply controls that can ensure stable and uninterrupted supply of electricity following a disturbance. The subject of stability thus encompasses modelling, computation of load flow in the transmission grid, stability analysis under both steady-state and disturbed conditions, and appropriate controls to enhance stability. All these topics are covered in this book, providing a comprehensive treatment of the overall subject of stability of power systems. Topics covered include modelling of the synchronous machine; the synchronous machine connected to power systems; modelling of transformers, transmission lines and loads; power flow analysis; optimal power flow; small signal stability; transient stability; transient energy function methods; artificial intelligent techniques; power system stabilizers; series compensation; shunt compensation; compensation devices; and recent technologies. The subject matter is covered at a level that is suitable for students, scientists and engineers involved in the study, design, analysis and control of power systems.

The integration of ICT into power systems has increased the interdependencies between the two systems. The operation of power system depends on several ICT-enabled grid services which manifest the interdependencies. ENTSO-E system state classification is a tool that is widely used by operators to determine the current operational state of the power system. However, it does not adequately describe the impact of ICT disturbances on the operation of the power system. Despite their interconnections, the operational states of both systems have been described separately so far. This paper bridges the well-established ENTSO-E systems state classification with an ICT system state classification, forming a new model considering the state classification of the ICT-enabled grid services. The model is developed by first identifying the ICT-enabled services, remedial actions and the respective performance requirements that are required by the power system. Then the states of these services are specified based on the supporting ICT system. The resulting joint state description shows how performance degradation of ICT-enabled services (introduced by disturbances) can affect the operation of the interconnected power system. Two case studies of such ICT-enabled services, namely state estimation and on-load tap changer control, are investigated in terms of how their operational states affect the states of the power system. A third case study highlights the interdependencies that exist between the services. These case studies demonstrate the interdependencies that exist between power and ICT systems in modern cyber-physical energy systems, thus highlighting the usage of a unified system state description.

Energy and research on energy systems places a focus on all facets of electrical energy, as well as innovation in energy production and delivery, alternative resources, and efficient devices. Systems and equipment for converting, providing, and utilising energy as a kind of electricity are the subject of research initiatives. Power electronics are now a more integral part of power systems, enhancing quality and efficiency and fostering the gradual materialization of intelligent, efficient energy. Many different types of power electronics exist in power systems. The architectural study of changing electrical transformed from one medium to another is known as power electronics. Fields such as electronics reprocess or recover more than 80percent of the entire of the electricity produced at a world average rate of 3.4 billion kilowatts per hour each year. Power electronics converters, sometimes referred to as power converters or switching converters, are used to process or convert electrical energy. Electricity comes in two flavours: AC power and DC power. The distribution system is divided into AC distribution systems and DC distribution systems based on the type of power it uses. Power system analysis is an essential part of electrical power system design. Calculations and simulations are performed to verify that the electrical system, including the system components, is properly specified to perform as planned, withstand the expected stress, and be protected from failures. Advantages of Power Electronics: High power density electricity. Improved efficiency up to 99% in energy conversion. Because to its efficiency and dependability, switching power supply are also being used in medical devices with acoustically sensitive applications. Power system reliability, in general, relates to problems like service interruption and power outages. This is frequently described as a goal to try relying on codes specifically relevant to the consumer. SAIFI, SAIDI, and CAIDI are common dependability index values for US applications. DEMATEL (Decision Making Trial and Evaluation Laboratory) They are divided into analysis using the Nonmetal mineral product industry, General equipment manufacturing, Mining and washing of coal, Textile industry, Food manufacturing industry It is the interaction between the factors Visualized and assesses dependent relationships Through the structural model Also deals with identifying important. Power Electronics in Power Systems, Power Electronics in Transportation Systems, Energy Conservation, Heating & Lighting Control and Renewable Energy Integration Power Systems and Power Electronics in Power Electronics in Power Systems is got the first rank whereas is the Energy Conservation is having the Lowest rank. Power Systems and Power Electronics in Power Electronics in Power Systems is got the first rank whereas is the Energy Conservation is having the Lowest rank.

In this paper, a review of some recent results on power system control (PSC) is given. Some important methods on power system analysis and control are summarized. In addition, the theoretical challenges encountered in the structure preserving power systems are discussed. Furthermore, a detailed structure preserving power system model with flux linkages dynamics is proposed, which is a basic of power system analysis and transient stability improvement.

(English) Dynamic behavior of modern power system is increasingly influenced by the dynamics of power converters. At the generation level, a high volume of wind and solar energy with their large-scale power converters are replacing conventional synchronous generators. At the transmission level, many High Voltage Direct Current (HVDC) projects based on Modular Multilevel Converter (MMC) technology are commissioned to transfer offshore wind to the load centers, interconnect two non-synchronous AC grids, or two different nodes of the same AC grid (as an embedded link) to enhance the security of supply. The consumption level also faces such high integration of power converters since the modern flexible loads, such as electric vehicles, industrial motor drives, and recent hydrogen electrolyzers, are connected to the power system via power converters. Such transformation in generation, transmission, and consumption levels leads to the power dynamics that have never been experienced before in the conventional power systems. The high penetration of power converters may cause several challenges: reduction in the system total inertia and short-circuit current, excitation of undesirable interactions among control loops, reduction in stability margin, and loss of devices in the context of fault-ride through (FRT). Such challenges can be addressed by appropriate adjustments in the control systems of power converters. At the transmission level, this thesis focuses on improving the dynamic behavior of HVDC systems. A methodology is suggested to study the small-signal stability and evaluate potential interactions that may happen among control loops of two HVDC converter stations. Next, a multivariable controller based on H-inf design practice is developed to optimize the dynamic behavior of the system. As a follow-up study, mu-synthesis control approach is adopted to make HVDC control resilient against AC grid impedance variation. In the context of FRT performance, the fault operation of the HVDC system is improved by appropriate modification of the MMC control loops. Finally, a brief study on the DC voltage droop control design is conducted on a multi-terminal HVDC system. At the generation level, this thesis investigates the dynamic behavior of grid-forming control during fault events in a low-strength power system. It investigates the complication related to the existing grid codes and suggests two FRT controls for AC voltage support during fault recovery. As the last step, this thesis evaluates the feasibility of modern flexible loads to provide grid-forming services to the low-strength power grid. A hydrogen electrolyzer is used as an example and the operational constraints related to the hydrogen production are linked to the grid-forming functionalities. (Català) El comportament dinàmic del sistema de potència modern està cada vegada més influenciat per la dinàmica dels convertidors de potència. A nivell de generació, un gran volum d'energia eòlica i solar amb els seus convertidors de potència a gran escala està substituint els generadors síncrons convencionals. A nivell de transmissió, molts projectes de corrent continu d'alta tensió (HVDC) basats en la tecnologia Modular Multilevel Converter (MMC) s'encarreguen de transferir l'eòlica marina als centres de càrrega o interconnectar dues xarxes de CA per millorar la seguretat del subministrament. El nivell de consum també s'enfronta a una integració tan alta dels convertidors de potència, ja que les càrregues flexibles modernes, com ara vehicles elèctrics, accionaments de motors industrials i electrolitzadors d'hidrogen recents, es connecten al sistema elèctric mitjançant convertidors de potència. Aquesta transformació en els nivells de generació, transmissió i consum condueix a una dinàmica de potència que mai s'havia experimentat abans en els sistemes de potència convencionals. L'elevada penetració dels convertidors de potència pot provocar diversos reptes: reducció de la inèrcia total del sistema i de la potència de curtcircuit, excitació d'interaccions indesitjables entre llaços de control, reducció del marge d'estabilitat i pèrdua de dispositius en el context de fallada (FRT). Aquests reptes es poden abordar mitjançant ajustos adequats en els sistemes de control dels convertidors de potència. A nivell de transmissió, aquesta tesi se centra en la millora del comportament dinàmic dels sistemes HVDC. Es proposa una metodologia per estudiar l'estabilitat del senyal petit i avaluar les interaccions potencials que poden passar entre els bucles de control de dues estacions convertidores HVDC. A continuació, es desenvolupa un controlador multivariable basat en la pràctica de disseny H-inf per optimitzar el comportament dinàmic del sistema. Com a estudi de seguiment, s'adopta un enfocament de control de sintetització-mu per fer que el control HVDC sigui resistent a les variacions en la impedància de la xarxa de CA. En el context del rendiment FRT, el funcionament de falla del sistema HVDC es millora mitjançant les modificacions adequades als bucles de control MMC. Finalment, es realitza un breu estudi sobre el disseny de control de caiguda de tensió de CC en un sistema HVDC multiterminal. A nivell de generació, aquesta tesi investiga el comportament dinàmic del control de formació de xarxa durant esdeveniments de falla en un sistema d'energia de baixa inèrcia. Investiga la complicació relacionada amb els codis de xarxa existents i suggereix dos controls FRT per al suport de la tensió de CA durant la recuperació de fallades. Com a darrer pas, aquesta tesi avalua la viabilitat de càrregues flexibles modernes per proporcionar serveis de formació de xarxa a la xarxa elèctrica de baixa resistència. Com a exemple s'utilitza un electrolitzador d'hidrogen i les limitacions operatives relacionades amb la producció d'hidrogen estan vinculades a les funcionalitats de formació de la xarxa. (Español) El comportamiento dinámico de los sistemas eléctricos modernos está cada vez más influido por la dinámica de los convertidores de potencia. A nivel de generación, un gran volumen de energía eólica y solar con sus convertidores de potencia a gran escala están sustituyendo a los generadores síncronos convencionales. A nivel de transmisión, se están encargando muchos proyectos de corriente continua de alta tensión (HVDC) basados en la tecnología de convertidores multinivel modulares (MMC) para transferir la energía eólica marina a los centros de carga, interconectar dos redes de CA no síncronas o dos nodos diferentes de la misma red de CA (como enlace integrado) para mejorar la seguridad del suministro. El nivel de consumo también se enfrenta a una integración tan elevada de los convertidores de potencia, ya que las cargas flexibles modernas, como los vehículos eléctricos, los accionamientos de motores industriales y los recientes electrolizadores de hidrógeno, se conectan al sistema eléctrico a través de convertidores de potencia. Esta transformación en los niveles de generación, transmisión y consumo da lugar a una dinámica de potencia nunca antes experimentada en los sistemas eléctricos convencionales. La alta penetración de los convertidores de potencia puede causar varios retos: reducción de la inercia total del sistema y de la corriente de cortocircuito, excitación de interacciones indeseables entre los bucles de control, reducción del margen de estabilidad y pérdida de dispositivos en el contexto de la conmutación por fallo (FRT). Estos retos pueden abordarse mediante ajustes adecuados en los sistemas de control de los convertidores de potencia. A nivel de transmisión, esta tesis se centra en mejorar el comportamiento dinámico de los sistemas HVDC. Se propone una metodología para estudiar la estabilidad de pequeña señal y evaluar las posibles interacciones que pueden producirse entre los lazos de control de dos estaciones convertidoras HVDC. A continuación, se desarrolla un controlador multivariable basado en la práctica de diseño H-inf para optimizar el comportamiento dinámico del sistema. Como estudio complementario, se adopta un enfoque de control mu-síntesis para que el control HVDC sea resistente a la variación de la impedancia de la red de CA. En el contexto del rendimiento FRT, se mejora el funcionamiento en fallo del sistema HVDC mediante la modificación adecuada de los bucles de control MMC. Por último, se realiza un breve estudio sobre el diseño del control de droop de tensión de CC en un sistema HVDC multiterminal. A nivel de generación, esta tesis investiga el comportamiento dinámico del control de formación de red durante eventos de fallo en un sistema eléctrico de baja tensión. Investiga la complicación relacionada con los códigos de red existentes y sugiere dos controles FRT para el soporte de tensión de CA durante la recuperación de fallos. Como último paso, esta tesis evalúa la viabilidad de las cargas flexibles modernas para proporcionar servicios de formación de red a la red eléctrica de baja potencia. Se utiliza como ejemplo un electrolizador de hidrógeno y se relacionan las restricciones operativas relacionadas con la producción de hidrógeno con las funcionalidades de formación de red.