Power System Transient Analysis Research Articles

Особенности моделирования воздушных и кабельных участков линий электропередачи 110–750 кВ при использовании фазного координатного базиса

Power system steady state and transient analysis require correct modeling of overhead transmission lines and cables operating at 110–750 kV. The key difficulties to model sections of overhead and cable lines are caused by complex conductor geometry, their transposition, as well as grounding schemes of ground wires of overhead lines and screens of underground cables. The paper covers various aspects of 110–750 overhead line and cable modeling that must be taken into consideration to obtain a reliable mathematical model in a phase domain. Modern software does not provide a universal solution to determine line parameters. The 110–500 kV cable line modeling issues have not been worked out properly and require careful analysis of specialized foreign literature. Thus, the task to develop the algorithms of calculating the parameters of overhead and cable power lines is relevant, taking into account the various configuration options of these lines which are possible in operational practice. To derive overhead transmission line and cable line models, electric circuit theory and matrix algebra methods have been used. The ATP/ATPDraw and MATLAB/Simulink software environment has been used to investigate what tools are available to determine line parameters, as well as to verify some of the calculation results. Analysis has been carried out to reveal the options available in the ATP/ATPDraw and MATLAB/Simulink software to compute line parameters in a phase domain. An algorithm has been developed and verified to calculate overhead line parameters regardless of the number of parallel circuits. The key features of the calculation of the matrix of linear resistances of overhead power transmission lines are outlined. The main features of modern cable lines operating at 110–500 kV are also described. The paper presents various cable layouts possible in real-field conditions, as well as provides expressions that allow obtaining correct impedances and admittances for a system of cable line conductors. Study of the options of various software tools dedicated to overhead line parameter calculation in a phase domain has revealed that these tools cannot be deemed universal to represent an overhead line of whatever configuration. However, the developed algorithm is universal as it allows computing line parameters regardless the ground wire grounding approach. The expressions presented in this paper consider various layouts of 110–500 kV cable lines that could be encountered in the Russian power system.

Preface

The 2022 5th International Conference on Mechanical, Electrical and Material Application (MEMA 2022) was successfully held on June 17-19, 2022. Due to the COVID-19 pandemic around the world, and with the strict travelling rules in China, it is still difficult to take international travel for our attendees abroad. Therefore, MEMA 2022 was held both in physical (Chengdu, China) and online (Zoom).The conference focused on the latest research field of “Mechanical, Electrical and Material applications”, promoted the development and integration of related disciplines, grasped the international frontier trends in this field, exchanged the latest research results, and provided an international platform for domestic and foreign institutions of higher learning, scientific research institutes, experts, professors, scholars, engineers, etc. to share professional experience, expand professional networks, exchange new ideas face-to-face and display research results, to explore the key challenges and research directions facing the development of this field. Focused on the latest research results of experts and scholars in the key areas of mechanical electrical technology and material equipment around the world, and carried out high-level, three-dimensional and international academic exchanges and cooperation. Through exchanges from different disciplines and fields, we will forge innovative ideas, stimulate innovative sparks, and accumulate strength to promote the development of related fields and industries and grasp a new wave of scientific and technological and industrial change. Experts and scholars in related fields are welcome to actively submit articles to participate in the conference.During the conference, the conference model was divided into three sessions, including oral presentations, keynote speeches, and online Q&A discussion. In the first part, some scholars, whose submissions were selected as the excellent papers, were given about 5-10 minutes to perform their oral presentations one by one. Then in the second part, keynote speakers were each allocated 30-45 minutes to hold their speeches.There were over 150 experts and scholars in the area of mechanical, electrical and material application representing different famous universities and institutes around the globe to attend this hybrid conference. During the conference, we were pleased to invite four distinguished experts to present their insightful speeches. The first keynote speaker, Prof. Kai Yang, Huazhong University of Science and Technology, China. And then we had Prof. Valentina E. Balas, Aurel Vlaicu University of Arad, Romania. Her research interests are in Intelligent Systems, Fuzzy Control, Soft Computing, Smart Sensors, Information Fusion, Modeling and Simulation. Prof. Prof. Junxi Bi, Inner Mongolia University of technology. His main directions include reliability design, manufacturing, optimization and control of complex electromechanical equipment; Fault diagnosis and performance prediction of large equipment; Digital machining and intelligent manufacturing technology. Our finale keynote speaker, Assoc. Prof. Guomin Luo, Beijing Jiaotong University. She has been engaged in the research of power system transient signal analysis and processing for a long time. Their insightful speeches had triggered heated discussion. Every participant praised this conference for disseminating useful and insightful knowledge.List of Committee member is available in this Pdf.

Evaluating the significance of samples in deep learning-based transient stability assessment

Deep learning-based transient stability assessment has achieved big success in power system analyses. However, it is still unclear how much of the data is superfluous and which samples are important for training. In this work, we introduce the latest technique from the artificial intelligence community to evaluate the significance of the samples used in deep learning model for the transient stability assessment. From empirical experiments, it is found that nearly 50% of the low-significance samples can be pruned without affecting the testing performance at the early training stages, thus saving much computational time and effort. We also observe that the samples with the fault-clearing time close to the critical clearing time often have higher significance indexes, indicating that the decision boundary learned by the deep network is highly related to the transient stability boundary. This is intuitive, but to the best of our knowledge, this work is the first to analyze the connection from sample significance aspects. In addition, we combine the stability scores with the significance index to provide an auxiliary criterion for the degree of stability, indicating the distance between a sample and the stability boundary. The ultimate goal of the study is to create a tool to generate and evaluate some benchmark datasets for the power system transient stability assessment analysis, so that various algorithms can be tested in a unified and standard platform like computer vision or natural language-processing fields.

Grid-Supportive Loads—A New Approach to Increasing Renewable Energy in Power Systems

This paper demonstrates the potential of inverter-based loads to support grid reliability during power system transients thereby enabling reliable integration of renewable energy in power systems. Such loads are referred to in this paper as grid-supportive loads (GSLs). A new GSL model is developed that simulates the transient response capabilities that can be programmed in electronic loads. The model’s design enables it to be easily integrated in widely used commercial power system transient analysis software. Theoretical expressions are derived that explain the workings of the GSL model. The performance, numerical stability, and impact of the GSL model is validated on 9-bus and 2000-bus synthetic power system models using generator tripping and bus fault disturbances. Results on the 2000 bus system show that in the absence of frequency support from wind/solar generation resources, just 20% of loads with grid-supportive capabilities can improve frequency response by up to 2000 MW/0.1 Hz and reduce deviation in frequency at nadir by up to 60% compared to the situation when GSLs are absent. Power system reliability also improves under fault events. It is further shown that GSLs can aid in integrating more renewable generation without degrading the overall transient response of the power system.

Transient overvoltage analysis in the medium voltage substations based on full-wave modeling of two-layer grounding system

In this paper, a comprehensive investigation of substation grounding soil structure effects on switching/lightning transients is presented. The full-wave computational solution Method of Moments (MoM) is adopted to solve Maxwell’s equations. The significant advantage of this technique is its ability to deal effectively with substation grounding systems (SGSs) at high frequency. This evaluation is carried out considering two soil structures: (1) a uniform soil and (2) soil with a layered structure. The impacts of both soil structures on the peak transient overvoltage values are compared. To begin with, the harmonic impedance matrix (HIM) of the layered multi-terminal SGS is computed. Then, a vector fitting approach is employed to incorporate the accurate SGS behavior by relying on the obtained HIM into time domain simulations. Finally, the transient overvoltages and maximum ground potential rise (GPR) are computed. The chief contribution of this paper is the transient assessment of the two-layer multi-terminal soil structure of the large SGS taking into account the frequency dependence model of the electrical parameters of soil, which is not generally investigated and instead, treated simplistically. According to the results of the study, the lack of an exact grounding system models may lead to underestimations/overestimations of the GPR and the overvoltage values. The results demonstrate the need for the grounding modeling of SGS considering layered soil structure to be incorporated into power system transient analysis in a wide range of frequencies.

Akihiro ametani: paving the way to power grid expansion through innovation in power system transient analysis [history

Akihiro Ametani was born in Nagasaki, Japan, on 14 February 1944. He received the B.Sc. and M.Sc. degrees from Doshisha University, Kyoto, Japan, in 1966 and 1968, respectively, and the Ph.D. degree from the University of Manchester, England, in 1973. He was with the Bonneville Power Administration (BPA), Portland, Oregon, from 1976 to 1981 and 1991 to 1992, where he contributed to the development of the Electromagnetic Transient Program (EMTP). He was a professor at Doshisha University from 1974 to 2014.

Transient Analysis of Multiphase Transmission Lines Located above Frequency-Dependent Soils

This paper evaluates the influence of frequency-dependent soil conductivity and permittivity in the transient responses of single- and double-circuit transmission lines including the ground wires subjected to lightning strikes. We use Nakagawa’s approach to compute the ground-return impedance and admittance matrices where the frequency-dependent soil is modeled using Alípio and Visacro’s model. We compare some elements of these matrices with those calculated by Carson’s approach which assumes the frequency constant. Results show that a significant difference can be obtained in high resistive soils for these elements in impedance and admittance matrices. Then, we compute the transient responses for single- and double-circuit lines with ground wires located above soils of 500, 1000, 5000, and 10,000 Ω·m considering the frequency constant and frequency-dependent parameters generated for two lightning strikes (subsequent stroke and Gaussian pulse). We demonstrate that the inclusion of frequency dependence of soil results in an expressive reduction of approximately 26.15% and 42.75% in the generated voltage peaks in single- and double-circuit lines located above a high-resistive soil. These results show the impact of the frequency-dependent soils that must be considered for a precise transient analysis in power systems.

Book Reviews [7 books reviewed

The following seven books are reviewed: Handbook of Large Hydro Generators: Operation and Maintenance (Mottershead, G., et al; 2021); Heat Transfer—Principles and Applications (Forsberg, C.H.; 2021); Renewable Energy in Power Systems (Infield, D. and Freris, L.; 2020); Noise in Radio-Frequency Electronics and Its Measurement (Fouquet, F.; 2020); Polymers in Organic Electronics (Khalifeh, S.; 2020); Transient Analysis of Power Systems (Martinez-Velasco, J.A., ed.; 2020); and Lens Design Basics—Optical Design Problem-Solving in Theory and Practice (Gerhard, C.; 2020).

Generic EMT modeling method of Type-4 wind turbine generators based on detailed FRT studies

Developing effective electromagnetic transient (EMT) models of wind turbine generators (WTGs) is essential for power system transient analysis. However, manufacturer-specific EMT models are usually available as black boxes, which is not easy to be used in practical applications. To address this issue, a four-step generic EMT modeling method is proposed for type-4 WTGs based on detailed fault ride-through (FRT) studies. Step one, massive FRT field tests are conducted on type-4 WTGs, and generic FRT responses of active and reactive power are extracted and parameterized to characterize a wide variety of controller strategies of various vendors; Step two, piecewise expressions of active and reactive power responses are derived to formulate the detailed FRT processes, including the FRT control process during a fault, post-fault recovery control process, and their switching transients; Step three, a generic controller, to emulate the FRT responses, is implemented in the WTG model by automatically updating current references utilizing the derived analytical formulation; Step four, a stepwise identification method is proposed to identify the FRT control parameters, proportional-integral controller parameters, and circuit parameters. The proposed modeling method is verified by field tests, and the results show that the developed model can accurately capture the FRT behaviors of practical type-4 WTGs.

A time-domain electromechanical co-simulation framework for power system transient analysis with retainment of user defined models

This paper proposes a time-domain electromechanical co-simulation framework to accomplish concurrent running of multiple simulators in order to preserve user-defined models and allow maximum simulation accuracy for power system transient analysis. A middleware interface is developed to manage the interaction and synchronization of the multiple simulators via boundary model. Consequently, it eliminates the requirement of model conversion of each subsystem and thus ensure the user-defined models in each specific software are retained for entire system situational awareness. Preliminary testing results on 140-bus Northeastern Power Coordinating Council (NPCC) model validate the effectiveness and accuracy of the proposed framework for PSS/E and PSLF co-simulation.

Application of PLC based smart microgrid controller for sequential load restoration during station blackout of nuclear power plants

Post Fukushima nuclear disaster, the distributed energy resources (DERs) based integrated microgrid (IMG) is under consideration as an alternative source to strengthen the station blackout power supply in nuclear power plants. The complete IMG blackout during switching over from on-grid to islanded mode is still an outstanding issue. The biggest challenge is power restoration to loads within 3 min of time after making black-start operation of DERs. A conceptual design of programmable logic controller based smart microgrid controller is proposed in this research to meet these challenges. In addition to it, a suitable protection scheme is also suggested to avoid transitional collapse of safety power supply. The concepts of black-start and sequential load restoration process are validated by using PSCAD/EMTDC simulation platform, a widely used power system transient and switching operation analysis tool. This software allows the users to assemble the circuit graphically, run the simulation, analyze the results, and manage the data in a completely integrated graphical environment. Based on the analysis reported in this paper, it is observed that the fluctuations in voltage and frequency are high during black-start operation. Hence, power electronics based soft starter is suggested to overcome these issues.

Generic Model of Three-Phase (RE)BCO Resistive Superconducting Fault Current Limiters for Transient Analysis of Power Systems

This paper presents the modelling and implementation of a generic three-phase resistive superconducting fault current limiter (r-ScFCL) for transient analysis of ac power systems. The r-ScFCL consists of series-connected noninductive coils made of insulated commercially available (RE)BCO tapes operated in a liquid nitrogen bath, in parallel with a resistive shunt at room temperature. The model allows the prediction of the thermal and electrical behaviors of the device prior to, during, and after a fault. It was used to evaluate the impact of a three-phase r-ScFCL on the transient stability of a synchronous generator supplying an infinite bus through a step-up transformer and a transmission line. More specifically, the impact of the r-ScFCL design on fault current magnitude, device voltage, temperature, and recovery time was studied. For the chosen case study, the r-ScFCL did increase the stability of the power system. It was also found that parameters such as the length of the superconducting tapes, the number of tapes in parallel, and the shunt resistance can balance or unbalance the response of the r-ScFCL over the three phases during a fault.

A Galerkin Method-Based Polynomial Approximation for Parametric Problems in Power System Transient Analysis

Parametric problems in the transient analysis refer to the investigations of the relationship between parameters and dynamic behavior. To solve parametric problems, we propose a Galerkin method-based polynomial approximation. The proposed method uses a series of polynomials combined with coefficients to approximately represent state variables with parameters, where the Galerkin method is introduced to determine the coefficients. Thereby, the relationship between parameters and dynamic behavior is established through the polynomial expressions. Because models in power system transient analysis are a set of complicated differential-algebraic equations, practical issues related to the non-polynomial model terms, parameterization of initial operation point are discussed in this paper. The proposed method is tested on a three-machine system and the IEEE 145-bus test system. The case studies show that compared to trajectory sensitivities, the proposed method can maintain high accuracy in cases of large parameter variations and strong non-linearity. We also illustrate that the validity of the proposed method for parametric problems like trajectory approximation, finding the critical parameter values and uncertainty quantification.

Model Reduction of DFIG Wind Turbine System Based on Inner Coupling Analysis

The doubly-fed induction generator (DFIG) wind turbine system, which is composed of the wind turbine, generator, rotor-side converter, grid-side converter, and so on, is a typical multi-time scale system. The dynamic processes at different time scales do not exist in isolation. Furthermore, neglecting the coupling of parameters of different time scales to reduce the order of the model will lead to deviation between the simulation results and the actual results, which may not be suitable for power system transient analysis. This paper proposes an electromechanical transient model and an electromagnetic transient model of the DFIG wind turbine system that consider the interaction of multiple time-scale dynamic processes. Firstly, the paper applies the modal analysis method to explain the multi-time scale characteristics of the DFIG wind turbine system. Secondly, the variation in the eigenvalues of the DFIG wind turbine system before and after the order reduction and the coupling between variables and the system, as well as the coupling between variables of different time scales, are analyzed to obtain the preliminary 21-order simplified model. Thirdly, considering the weak coupling characteristics between the mechanical part and the electromagnetic part of the DFIG wind turbine system, the 21-order simplified model is decomposed into a 15-order electromagnetic transient model and a six-order electromechanical transient model on the basis of their time scales. Then, according to the balance between simulation time and simulation accuracy, the 14-order electromagnetic transient model and the 10 or 12-order electromechanical transient model are finally obtained. Finally, the rationality of the simplified models is verified by simulations under two large disturbance conditions, namely wind speed abrupt change and voltage sag. The obtained simplified models have reference significance for improving the simulation speed of a wind power grid-connected system and analyzing the internal mechanism of the DFIG wind turbine system’s stability.

Distributed Wind Energy Conversion System Interface to the Grid Using Cascaded Multi-Level Converter

ABSTRACTIn this paper, a distributed wind energy conversion system based on the cascaded H-bridge multi-level converter topology has been proposed to be used for the medium-voltage grid interface application. This includes load compensation and injection of real power requirement of the load. The load compensation includes reactive power compensation, load harmonic mitigation, and correction for the unbalancing problem. An algorithm has been proposed for generating references for the voltage source converter in current control mode in order to inject real power together with the reactive and harmonic components of the load. Modular structure of the wind turbine-alternator sets and cascaded multi-level inverter using H-bridges suits the distributed wind energy conversion system interface to the medium-voltage grid. The factors like equal distribution of switching stress and power losses, reduced power ratings of the inverter, redundancy, and high quality of inverter output voltage make the proposed arrangement efficient for high-power applications. The cascaded topology with phase-shifted multi-carrier pulse width modulation (PWM) has the features of increasing the effective switching frequency and reducing the ripple magnitude. The proposed scheme has been verified through the simulation study using power system transient analysis tool (PSCAD/EMTDC).

Identification of A Hysteresis Model Parameters Using the Differential Evolution Algorithm

Establishing the accurate mathematical and simulation model of transformer is the basis of the power system steady state and transient state analysis, but the nonlinear of the transformer main magnetic circuit makes it difficult to accurate analysis of the transformer and its system. Jiles-Atherton hysteresis model as one of the classical model of ferromagnetic materials, is a physical basis of phenomenological model. It enables the mathematical description of hysteresis curves using five parameters that depend on the magnetic material characteristics. This paper introduces a modified Jiles-Atherton static hysteresis model, and the inverse model was deducted. And then this paper identifies of a hysteresis model parameters using the differential evolution algorithm, and the calculated results are well agreed with the date.

LMI-Based Method for Estimating Passive Blackbox Models in Power Systems Transient Analysis

Power system transient analysis relies on the deployment of models with ever-increasing accuracy that represents the system's frequency-dependent components with respect to the phenomena being scrutinized. A key issue in this context is the construction of a model yielding passive properties for each system component. Such properties are commonly compromised by corrupting noise in measurements that serve as input to the computation of blackbox models. In addition, model passivity could be further compromised during parameter estimation. This paper undertakes the task of developing a proposal to build an optimization methodology based on linear matrix inequalities (LMI-based) which is intended for obtaining an optimal, passive, blackbox model for a $n$ -terminal power transformer. The resulting model can be further realized as a circuit representation in order to simulate the transformer dynamics in an Eletromagnetic Transient program (EMT type). The results derived from two operating power transformers are later provided to confirm how effective the procedure herein proposed is.

Development of Power System Transient Analysis Program based on Traveling Wave Theory using MATLAB

Abstract: In power system, there are various events such as fault. When this event are occurred, transient phenomena on power system are observed. To analyze the transient phenomena on power system, various theory or simulation/analysis tools are used. Traveling wave theory is also one of the analysis method for power system transient phenomena. Already, traveling wave theory is utilized various area, such as fault location on transmission system or electrical railroad system. It is known that analysis method based on traveling wave theory has advantage on the aspect of accuracy. In this paper, the traveling wave theory is implement on MATLAB program. Also, using MATLAB program based on traveling wave theory, power system transient phenomena is analyzed. To verify the accuracy of MATLAB program result, comparison with result of ElectroMagnetic Transient Program (EMTP) is performed.

Validation Limits of Quasi-TEM Approximation for Buried Bare and Insulated Cables

For the analysis of power system transients in overhead transmission lines and underground cables, a common assumption is related to the quasi-TEM (transverse electromagnetic) approximation. In this paper, we investigate the applicability of this approximation throughout a wide frequency band when both conduction and displacement currents in ground are considered, typically only the former is considered. A full-wave model is established to assess the behavior of the propagation constant for bare and insulated underground cables in a wide frequency band and verify the adequacy of the quasi-TEM approximation. The results demonstrate that it is possible to retain quasi-TEM approximations in the high-frequency range as well. One has only to consider different assumptions for the propagation constant. For the evaluation the adequacy of the quasi-TEM approximation, a simple, single-phase buried cable is considered. The effect of the cable coating is also taken into account and the results indicate that the quasi-TEM approximation is rather distinct for bare or insulated cables. The accuracy of the approximation is evaluated from comparison of step and impulse voltage tests considering different soil models.

Development of a New Superconducting Generator Model for Power System Transient Analysis with XTAP

Superconducting generators (SCGs) are considered to bring many advantages to electric power grids such as high generation efficiency, improvement of power quality, capability to enhance power system stability, and so on. In order to investigate these benefits in the conditions similar to those of a real power system, electromagnetic transient (EMT) analysis in three-phase instantaneous values is very useful. In this study, a new SCG model for power system transient analysis has been developed with an EMT software named Expandable Transient Analysis Program. Novelty of the newly developed model is in the calculation procedure using a two-stage diagonally implicit Runge-Kutta method and a second-order Runge-Kutta method (RK2). The proposed method enabled us to interface the SCG model with the outer power system without prediction or delay. The method is considered to enhance the numerical stability of transient analyses including SCGs by explicitly limiting the integral calculation errors through the use of RK2. It was confirmed that the developed model is useful to EMT analysis including SCGs.