Traveling-Wave-Based Fault Location in Electrical Distribution Systems With Digital Simulations

Traveling-wave-based fault location in electrical distribution systems is an important safeguard for the distribution network reliability. The effectiveness of the methods is verified directly in power grid in the early stages, while different fault types can't appear in a short time. And normal dynamic physical simulation cannot meet the teaching demand either because of the limitation of transmission line model and other factors. So PSCAD/EMTDC and MATLAB are used to illustrate the the fault location methods in this paper, which can promote the traveling-wave-based fault-location technology. Meanwhile, the traveling-wave-based fault-location method based on characteristic frequencies is analyzed in this paper

LLMVA-GEBC: Large Language Model with Video Adapter for Generic Event Boundary Captioning

Our winning entry for the CVPR 2023 Generic Event Boundary Captioning (GEBC) competition is detailed in this paper. Unlike conventional video captioning tasks, GEBC demands that the captioning model possess an understanding of immediate changes in status around the designated video boundary, making it a difficult task. This paper proposes an effective model LLMVA-GEBC (Large Language Model with Video Adapter for Generic Event Boundary Captioning): (1) We utilize a pretrained LLM for generating human-like captions with high quality. (2) To adapt the model to the GEBC task, we take the video Q-former as an adapter and train it with the frozen visual feature extractors and LLM. Our proposed method achieved a 76.14 score on the test set and won the first place in the challenge. Our code is available at https://github.com/zjr2000/LLMVA-GEBC .Comment: Winner solution to Generic Event Boundary Captioning task in LOVEU Challenge (CVPR 2023 workshop

Faulted Feeder Identification Based on Active Adjustment of Arc Suppression Coil and Similarity Measure of Zero-Sequence Currents

Existing faulted feeder identification methods in the resonant grounded distribution network are primarily based on feature extraction of the fault-generated transient currents. The reliability of these approaches is significantly compromised by the fluctuating transient signals and interfering on-off operation of the neighboring switches. To sidestep the problems, a novel method is proposed to identify the faulted feeder by consecutively tuning the arc suppression coil around the full compensation state. Once a series of steady states are reached after tuning, the trajectories of the corresponding zero-sequence currents for both the sound and the faulted feeders are obtained to formulate an adjustment trajectory matrix (ATM). With the ATM, the similarity measure of the adjustment trajectories of all feeders is then employed to identify the faulted feeder based on the selected Deng\u27s grey relational analysis. Results show that the adjustment trajectories of the two sound lines share a high similarity degree, while the similarity between the sound and the faulted lines is much lower. The effectiveness of the proposed method is validated via simulation and some case studies are provided. The results show that the faulted feeder can be correctly identified with high reliability and robustness compared to the existing fault-generated signal-based techniques

Combined Primary Frequency and Virtual Inertia Response Control Scheme of Variable-Speed Dish-Stirling System

The potential of variable-speed dish-Stirling (VSDS) solar-thermal generating plant in providing grid frequency support is investigated. In the proposed VSDS frequency support control scheme, the reference speed of the Stirling engine is regulated to track a deloaded power curve which is governed by the solar insolation level. The gain of a supplementary speed-frequency droop controller is then set to meet the primary frequency control requirement. Further uniqueness of the VSDS control scheme pertains to the provision of virtual inertia response by regulating the kinetic energy in the rotating mass of the engine-generator and the thermal energy in the heat absorber/receivers. Small-signal analysis shows that the frequency support scheme is inherently stable, and it will provide higher degree of damping as the penetration level of the VSDS system and/or the solar insolation level increase. The efficacy of the proposed scheme is validated by computer simulation

Control-Oriented Modeling of All-Solid-State Batteries Using Physics-Based Equivalent Circuits

Considered as one of the ultimate energy storage technologies for electrified transportation, the emerging all-solid-state batteries (ASSBs) have attracted immense attention due to their superior thermal stability, increased power and energy densities, and prolonged cycle life. To achieve the expected high performance, practical applications of ASSBs require accurate and computationally efficient models for the design and implementation of many onboard management algorithms, so that the ASSB safety, health, and cycling performance can be optimized under a wide range of operating conditions. A control-oriented modeling framework is thus established in this work by systematically simplifying a rigorous partial differential equation (PDE) based model of the ASSBs developed from underlying electrochemical principles. Specifically, partial fraction expansion and moment matching are used to obtain ordinary differential equation based reduced-order models (ROMs). By expressing the models in a canonical circuit form, excellent properties for control design such as structural simplicity and full observability are revealed. Compared to the original PDE model, the developed ROMs have demonstrated high fidelity at significantly improved computational efficiency. Extensive comparisons have also been conducted to verify its superiority to the prevailing models due to the consideration of concentration-dependent diffusion and migration. Such ROMs can thus be used for advanced control design in future intelligent management systems of ASSBs

Characteristics of Phase Current and its Application in Fault Section Location in Noneffectively Grounded Distribution Systems

Medium voltage distribution systems of some countries are mostly noneffectively grounded systems, and most of the distribution automation systems do not have the function of locating the fault section for single phase-to-ground fault. This paper presents a method of fault section location based on the characteristic of the phase current difference. It makes a deep analysis based on instantaneous symmetrical component method when single phase-to-ground fault happens. This method requires only a little data to be transferred and does not need voltage information, so it is easy to be popularized and applied in engineering practice. The effectiveness of the method has been verified by the PSCAD/EMTDC simulation results

A Novel Faulty Phase Selection Method for Single-Phase-to-Ground Fault in Distribution System Based on Transient Current Similarity Measurement

In modern electrical power distribution systems, the effective operation of inverter-based arc suppression devices relies on the accuracy of faulty phase selection. In the traditional methods of faulty phase selection for single-phase-to-ground faults (SPGs), power frequency-based amplitude and phase characteristics are used to identify the faulty phase. In the field, when a high-resistance SPG occurs in the system, traditional methods are difficult for accurately identifying the faulty phase because of the weak fault components and complicated process. A novel realizable and effective method of faulty phase selection based on transient current similarity measurements is presented when SPGs occur in resonantly grounded distribution systems in this paper. An optimized Hausdorff distance matrix (MOHD) is proposed and constructed by the transient currents of three phases’ similarity measurements within a certain time window of our method. This MOHD is used to select the sampling time window adaptively, which allows the proposed method to be applied to any scale of distribution systems. Firstly, when a SPG occurs, the expressions for the transient phase current mutation in the faulty and sound phases are analyzed. Then, the sampling process is segmented into several selection units (SUs) to form the MOHD-based faulty phase selection method. Additionally, the Hausdorff distance algorithm (HD) is used to calculate the waveform similarities of the transient phase current mutation among the three phases to form the HD-based faulty phase selection method. Finally, a practical resonant grounded distribution system is modeled in PSCAD/EMTDC, and the effectiveness and performance of the proposed method is compared and verified under different fault resistances, fault inception angles, system topologies, sampling time windows and rates of data missing

Research on application of active current differential protection method on AC transmission lines in UHV AC–DC interconnected system

The rapid development of ultra-high voltage (UHV) AC–DC interconnected system has brought with it some new features, such as characteristics of distributed parameters becoming more distinct, internal parameters changing faster, and harmonic becoming more unstable, which pose new challenges for the correct operation of relay protection and automation devices. The aim here is to study the application of active current differential protection method in UHV AC–DC interconnected system. Firstly, the negative influence of UHVDC connection on the effectiveness of traditional current protection method is analysed. Next, the principle of active current differential protection method is introduced, which shows that this method is less susceptible to the variation of system parameters and unstable harmonics. On this basis, simulations have been conducted on PSCAD platform to explore the application of this method on AC transmission lines in case of various fault types. The simulation results show that the active current differential protection can increase the sensitivity of protection of UHV AC–DC interconnected system

Particle swarm optimization-based power and temperature control scheme for grid-connected DFIG-based dish-Stirling solar-thermal system

Variable-speed operation of a dish-Stirling (DS) concentrated solar-thermal power generating system can achieve higher energy conversion efficiency compared to the conventional fixed-speed operation system. However, tuning of the controllers for the existing control schemes is cumbersome due to the presence of a large number of control parameters. This paper proposes a new control system design approach for the doubly-fed induction generator (DFIG)-based DS system to achieve maximum power point tracking and constant receiver temperature regulation. Based on a developed thermo-electro-pneumatic model, a coordinated torque and mean pressure control scheme is proposed. Through steady-state analysis, the optimal torque is calculated using the measured insolation and it serves as the tracking reference for direct torque control of the DFIG. To minimize the tracking error due to temperature variation and the compressor loss of the hydrogen supply system, four optimal control parameters are determined using particle swarm optimization (PSO). Model-order reduction and the process of the pre-examination of system stability are incorporated into the PSO algorithm, and it effectively reduces the search effort for the best solution to achieve maximum power point tracking and maintain the temperature around the set-point. The results from computational simulations are presented to show the efficacy of the proposed scheme in supplying the grid system with smoothened maximum power generation as the solar irradiance varies

Development of an integrated power distribution system laboratory platform using modular miniature physical elements: A case study of fault location

The main shortcomings of the software-based power engineering education are a lack of physical understanding of phenomena and hands-on experience. Existing scaled-down analogous educational power system platforms cannot be widely used for experiments in universities due to the high cost, complicated operation, and huge size. An integrated power distribution system laboratory platform (PDSLP) using modular miniature physical elements is proposed in this paper. The printed circuit board (PCB) and microelectronic technology are proposed to construct each physical element. Furthermore, the constructed physical elements are used to set up an integrated PDSLP based on modular assembly technology. The size of the proposed cost-efficient PDSLP is significantly reduced, and the reliability of the proposed PDSLP can be improved greatly because the signal transmission path is shortened and a number of welding points are reduced. A PDSLP for fault location in neutral non-effectively grounded distribution systems (NGDSs) is selected as a typical experimental scenario and one scaled-down distribution network with three feeders is subsequently implemented and discussed. The measured zero-sequence currents by our proposed PDSLP when a single-phase earth fault occurred can reveal the true features of the fault-generated signals, including steady-state and transient characteristics of zero-sequence currents. They can be readily observed and used for students to design corresponding fault location algorithms. Modular renewable energy sources and other elements can be designed, implemented and integrated into the proposed platform for the laboratory education of the active distribution networks in the future