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The general expression is derived for the Laplace transform of the time-dependent transient electrophoretic mobility (with respect to time) of a spherical colloidal particle when a step electric field is applied. The transient electrophoretic mobility can be obtained by the numerical inverse Laplace transformation method. The obtained expression is applicable for arbitrary particle zeta potential and arbitrary thickness of the electrical double layer around the particle. For the low potential case, this expression gives the result obtained by Huang and Keh. On the basis of the obtained general expression for the Laplace transform of the transient electrophoretic mobility, we present an approximation method to avoid the numerical inverse Laplace transformation and derive a simple approximate analytic mobility expression for a weakly charged particle without involving numerical inverse Laplace transformations. The transient electrophoretic mobility can be obtained directly from this approximate mobility expression without recourse to the numerical inverse Laplace transformation. The results are found to be in excellent agreement with the exact numerical results obtained by Huang and Keh.

\"Widely accepted around the world, the BCU method is the only direct method used in the power industry. Direct Methods for Stability Analysis of Electric Power Systems presents a comprehensive theoretical foundation of the method and its numerical implementation. This book provides graduate students, researchers, and practitioners with theoretical foundations of direct methods, energy functions, and the BCU method as well as the group-based BCU method and its applications. Numerical studies on industrial models and data are also included\"-- \"This book describes the BCU method (Boundary of Stability Region Based Controlling Unstable Equilibrium Point method)\"--

The conventional automatic control method of transient frequency in new energy power system is mainly based on power fluctuation control of power system, and the dynamic characteristics and operation law of power system are not understood, which affects the effect of transient frequency control. Therefore, an automatic control method of transient frequency of new energy power system with double carbon target is designed. Control the transient frequency stability margin of the new energy power system, and arrange the operation mode of the power system reasonably according to the magnitude of the transient frequency stability margin to ensure that the power supply system can maintain stable operation after being disturbed. Based on the dual-carbon target, the active power of the new energy resource power supply system is automatically adjusted, taking into account the stability of the power supply system, the fluctuation of new energy resource generation, the change of load and other factors, making better use of new energy to generate electricity, reducing the dependence of the power system on fossil energy, and realizing the dual-carbon target on the basis of controlling the transient frequency. The simulation results show that the transient frequency control effect of this method is better and can be applied to real life.

In order to overcome the problems of poor understandability of the pattern recognition-based transient stability assessment (PRTSA) methods, a new rule extraction method based on extreme learning machine (ELM) and an improved Ant-miner (IAM) algorithm is presented in this paper. First, the basic principles of ELM and Ant-miner algorithm are respectively introduced. Then, based on the selected optimal feature subset, an example sample set is generated by the trained ELM-based PRTSA model. And finally, a set of classification rules are obtained by IAM algorithm to replace the original ELM network. The novelty of this proposal is that transient stability rules are extracted from an example sample set generated by the trained ELM-based transient stability assessment model by using IAM algorithm. The effectiveness of the proposed method is shown by the application results on the New England 39-bus power system and a practical power system--the southern power system of Hebei province.

HVDC systems with high voltage and direct current are suitable for reducing electricity losses, during transmission over long distances. However, HVDC lines have the highest probability of failure within a system and can be damaged by different faults or lightning strikes. This paper presents a transient circuit model for the practical Egypt–Saudi Arabia link. The transient potential at different points along the line is calculated under different magnitudes and shapes of lightning strokes. \"Additionally, the extent of transient overvoltages at the rectifier station due to shifts in lightning strike locations has been estimated. Furthermore, overvoltage distributions are examined caused by lightning strikes on a real ± 500 kV hybrid HVDC TL-Cableare examined. To prevent national disasters and maintain safe national ratios of electrical production, particularly in the case of hybrid HVDC TL-Cable faults, an analysis of different AC/DC faults in the hybrid HVDC TL-Cable is also presented. This study is based on an equivalent electrical model using Power Systems Computer-Aided Design (PSCAD) software. It was discovered that severe voltages appear at the rectifier station when 50 kAlightning stroke with 1.2 μ sec front time, and 350 μ sectail time hits the TL. Moreover, overvoltages are reduced by about 58% in hybrid HVDC TL-Cable. Also, surge arresters at rectifier stations reduce overvoltages by approximately 95%. Ultimately, DC pole-to-ground faults are more serious than other types of faults and can cause massive overcurrent in the system, potentially damaging the rectifier station.

Transient stability analysis is critical for maintaining the reliability and security of power systems. This paper provides a comprehensive review of research methods for transient stability analysis under large disturbances, detailing the modeling concepts and implementation approaches. The research methods for large disturbance transient stability analysis are categorized into five main types: simulation methods, direct methods, data-driven methods, analytical methods, and other methods. Within the analytical method category, several common analytical strategies are introduced, including the asymptotic expansion method, intrusive approximation method, and other analytical methods. The fundamental principles, characteristics, and recent research advancements of these methods are detailed, with particular attention to their performance in various aspects such as computational efficiency, accuracy, applicability to different system models, and stability region estimation. The advantages and disadvantages of each method are compared, offering insights to support further research into transient stability analysis for hybrid power grids under large disturbances.

This paper analyzes the transient voltage stability of the dual-source DC power system. The system’s equivalent model is first established. Subsequently, the effect mechanisms of line parameters and voltage-source rectifiers’ current control inner loops on the system’s transient voltage instability are investigated. It indicates that these factors reduce the power supply capacity of the source, increasing the risk of transient instability in the system. Then, considering the influence of fault depths, the influence of different large disturbances on the transient voltage stability is investigated. Furthermore, the critical cutting voltage and critical cutting time for DC power systems are determined and then validated on the MATLAB R2023b/Simulink platform. Finally, based on the mixed potential function theory, the impact of system parameter variations on stability boundaries is analyzed quantitatively. Simulation verification is conducted on the MATLAB R2023b/Simulink platform, and experimental verification is conducted on the RT-LAB Hardware-in-the-Loop platform. The results of the quantitative analysis and experiments corroborate the conclusions drawn from the mechanistic analysis, underscoring the critical role of line parameters and converter control parameters in the system’s transient voltage stability.

This paper explores how different control strategies—grid-forming and grid-following—impact the transient stability of modular multilevel converters (MMCs) interfacing with AC power grids. By employing electromagnetic transient simulation tools (PSCAD/EMTDC) on an adapted IEEE three-machine, nine-bus system, various scenarios are analyzed, including faults of differing types and locations. In the simulation, traditional synchronous generators (SGs) are replaced by MMCs configured under distinct control modes. Results indicate that grid-forming (GFM) control enhances the receiving-end grid’s transient stability by providing superior phase support and extended fault-clearing times compared to grid-following (GFL) control, with hybrid approaches yielding intermediate performance. These findings underline the importance of converter control selection in achieving robust dynamic operation in modern power systems with a high penetration of renewable energy.

The problems associated with the stability analysis of power system are very important and has a wide scope of improvement. Severity of the transient disturbances arising in power system are usually studied through critical contingencies simulation. There proper study and assessment is extremely important for a reliable, uninterrupted operation, along with ensuring that no generating unit get desynchronized. The main objective of this research is to develop a fast and robust online transient stability assessment tool to classify the system operating states and to identify system critical generators in case of instability. This research proposes a pipeline machine learning multi-feature hybrid network framework that captures the phasor measurement unit (PMU) measurements and monitor the system transient stability in real-time. The test results verified that our proposed framework is fast and accurate, thereby a viable approach for system stability monitoring applications.

The ice disaster has brought many adverse effects on the power transmission system, which is mainly studied from the transmission line failure rate perspective. Strong winds often accompany the ice disaster weather, the motion path of wind is considered when identifying the weak location of transmission network system. According to the theory of meteorological simulation, and the mathematical relationship between the effective wind speed and the forced outage rates is obtained. A transient stability risks assessment method is proposed considering the ice disaster in the case of a strong wind moving path. According to the fault probability of transmission lines, a predictive fault set for power grid risk assessment is established. The IEEE-39 bus system is used as an example to analyze the effectiveness of the proposed method. The simulation results show that meteorological parameters, geographical environment, and other factors, especially the meteorological advance speed and the direction of transmission lines, will cause greater damage to the stability of the transmission system.