Fast Fault Isolation Research Articles

Control and fault diagnosis for two-interleaved boost converter associated with to PEMFC

This paper presents an enhanced control and fast fault detection method, localisation and isolisation for a two-phase interleaved boost DC/DC converter specifically designed for fuel cell applications. Fuel cells are known for their rapidly changing output voltage and current due to fluctuating load demands. Conventional converters might not be able to respond fast enough to maintain stable operation under such conditions.The two-phase interleaved design offers significant advantages. such as reduced ripple current delivered by dividing the Input current, the converter significantly lowers input and current ripple compared to single-phase designs. Each phase handles a smaller portion (1/N) of the total current, leading to reduced stress on individual components and enhanced reliability and operating margins. Additionally, Interleaving minimizes conduction losses by dividing the current among multiple converter stages. This work presents a model of a two-phase interleaved boost DC/DC converter and implements a PI controller for its output voltage regulation. This control method guarantees good performance even under varying reference voltages and load conditions. The proposed algorithm addresses the challenge of open circuit switch failures by utilizing current slopes for swift fault detection and rapid corrective action. This ensures accurate reference tracking, desired dynamic response, and timely fault detection and localization. The entire system was rigorously tested using MATLAB/Simulink software under various conditions, including reference voltage and load variations, as well as open circuit switch faults. The results showcase the proposed system's superior performance in terms of: Dynamic performance: The system exhibits rapid response to changes in operating conditions. Fast fault detection, localization and isolation.

A Fast and Low-Cost Open-Circuit Fault Detection and Isolation Technique for Three-Phase Dual-Active-Bridge Converters Based on Finite State Machines

A Fast and Low-Cost Open-Circuit Fault Detection and Isolation Technique for Three-Phase Dual-Active-Bridge Converters Based on Finite State Machines

Multiple fault isolation method for micro thrusters of drag-free systems

This paper proposes a multiple fault isolation framework for micro thrusters of drag-free systems, based on the minimum number of isolation filters. Based on the consideration of fault isolatability, the original system is reasonably divided into two completely isolated subsystems, and then two sets of fault isolation filters are designed based on the principles of duality design for state feedback decoupling, which achieves residual decoupling, and therefore, can detect and isolate multiple faults occurred on the micro thrusters. In particular, this method has low computational burden (a feature of practical importance in reducing the usage of onboard resources) and short isolation time, making it suitable for on-board fast and precise fault isolation. The simulation results demonstrate the efficacy of the proposed method when utilized for a drag-free system with 12 field emission electric propulsion (FEEP) thrusters.

Multiple Open-Circuit Fault Detection and Isolation Using Universal Low-Cost Diagnosis Circuits for Reconfigurable Dual-Active-Bridge Converters

Compared with single-switch open-circuit faults (SOCFs), multiple switches open-circuit faults (MOCFs) of power electronic devices (PEDs) due to high voltage or current stress, false triggering, and manufacturing tolerance have become more challenging. To address this issue, a reconfigurable dual-active-bridge (R-DAB) converter is presented with a fast, accurate, robust, and low-cost fault detection (FD) and fault isolation (FI) scheme to accommodate both SOCFs and MOCFs. Compared with the standard dual active bridge (DAB) topology, the proposed R-DAB will utilize a center-tapped high-frequency transformer and two symmetrical auxiliary inductors, where inherent half-bridge conduction branches are capable of maintaining uninterrupted operations. The proposed FD and FI scheme is straightforward and universal since only the center-tap current in the primary and secondary bridge is monitored as the universal fault signature. Moreover, a simple and low-cost fault diagnostic circuit was designed, which can detect and isolate various open circuit faults (OCFs) of PEDs under varying input and output conditions, without using expensive voltage and current sensors. This sensorless fault diagnosis technique can achieve the fastest fault detection and isolation speed reported so far, which is within a couple of \boldmath <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu s$</tex-math></inline-formula> for various OCFs. Experimental results were acquired from an R-DAB prototype under various OCFs to validate the effectiveness of the proposed technique.

Synchronous and fault-tolerance control for dual-motor steer-by-wire system of commercial vehicle

In order to meet the high safety requirement of high-level automatic steering mechanism for commercial vehicle, a kind of steer-by-wire (SBW) system with redundant motors is studied in this paper, and the structure principle and control strategy of the system are studied. Commercial vehicles have the characteristics of large steering resistance moment, which is accompanied by impact and vibration during steering, so the synchronous control of dual motors is the key and difficult problem. Based on the circulating ball steering gear for commercial vehicle, dual-motor synchronous control architecture is designed and the dual-motor global-fast-terminal-sliding-mode (nonsingular-GFTSM) synchronous control is formulated. Compared with the sliding-mode control, the simulation results show that the dual-motor actuator based on nonsingular-GFTSM can better realize the synchronous operation in angle, speed and torque. In addition, a real-time motor fault-diagnosis method based on sliding mode observer and a fault-tolerant control strategy based on smooth switching system are designed, which can achieve fast fault-isolation and smooth torque switching in case of actuator failure in dual-motor system. A Hardware-in-the-Loop (HIL) test bench is built to further verify the effectiveness of the synchronous and fault-tolerance control strategy for dual motors.

A Differential Protection Scheme Based on Improved DTW Algorithm for Distribution Networks With Highly-Penetrated Distributed Generation

Differential protection has been introduced into the distribution network to address the ineffectiveness of traditional protection due to the uncertainties of power flow caused by the access of multiple inverter-interfaced distributed generation (IIDG). Designed for lower data synchronization costs, this paper proposes a novel differential protection scheme based on improved dynamic time warping (DTW) distance. The proposed algorithm can effectively alleviate the singularity caused by DTW’s excessive X-axis distortion through relaxation search and derivative estimation and minimize the impact of data synchronization errors and data loss. Based on the proposed algorithm, the protection scheme combined with the feeder terminal unit (FTU) for fast fault isolation is designed, which can make full use of the existing equipment and reduce costs. Moreover, multiple influencing factors considered in this scheme, including transition resistance, penetration rate, and output intermittency of IIDG, variable network topology, underground cables, and hybrid lines. The test results demonstrate that the proposed protection scheme can effectively isolate short-circuit faults in various scenarios.

Residual-based Short-Circuit fault detection and isolation in LVDC microgrid

Designing protection for a DC microgrid is challenging due to its DC nature and heavily capacitor-dominated DC bus that induces high amplitude current spike during short-circuit faults. Moreover, for small-scale applications such as residential DC microgrids, low line-resistance cables increase the fault detection time constraint. Thus, this paper proposes a fast short-circuit fault detection and isolation method based on current residual computation for a standalone residential DC microgrid. The proposed method continuously compares the computed residual from sensed branch currents to their respective defined thresholds. These thresholds are predetermined by analyzing the microgrid operation in healthy mode, considering both steady-state and transient operations. The protection device isolating the faulty branch is then activated once the corresponding residual exceeds its threshold. The protection scheme is validated through a processor-in-the-Loop simulation approach, during which the power stage of the system remains simulated on the host computer using PSIM software, while its control algorithm is executed from a Texas Instrument TMS320F28335 hardware target. The proposed protection algorithm is able to discriminate transient perturbations due to load connection from short-circuit faults. Furthermore, the algorithm implementation is not limited by the size of the DC microgrid nor by the type of the connected loads.

Multiple-Actuator Fault Isolation Using a Minimal ℓ1-Norm Solution with Applications in Overactuated Electric Vehicles.

A multiple-actuator fault isolation approach for overactuated electric vehicles (EVs) is designed with a minimal -norm solution. As the numbers of driving motors and steering actuators increase beyond the number of controlled variables, an EV becomes an overactuated system, which exhibits actuator redundancy and enables the possibility of fault-tolerant control (FTC). On the other hand, an increase in the number of actuators also increases the possibility of simultaneously occurring multiple faults. To ensure EV reliability while driving, exact and fast fault isolation is required; however, the existing fault isolation methods demand high computational power or complicated procedures because the overactuated systems have many actuators, and the number of simultaneous fault occurrences is increased. The method proposed in this paper exploits the concept of sparsity. The underdetermined linear system is defined from the parity equation, and fault isolation is achieved by obtaining the sparsest nonzero component of the residuals from the minimal -norm solution. Therefore, the locations of the faults can be obtained in a sequence, and only a consistently low computational load is required regardless of the isolated number of faults. The experimental results obtained with a scaled-down overactuated EV support the effectiveness of the proposed method, and a quantitative index of the sparsity condition for the target EV is discussed with a CarSim-connected MATLAB/Simulink simulation.

Resilience enhancement strategy for multi-energy systems considering multi-stage recovery process and multi-energy coordination

With the increasing frequency of extreme weather events (EWEs) in recent years, the resilience of multi-energy systems (MESs) has received considerable attention. To improve the ability of MESs to withstand and recover rapidly from an EWE, this paper proposes a comprehensive resilience enhancement operation strategy for MESs considering the multi-stage recovery process and multi-energy coordination. Wherein, multi-stage recovery process throughout the pre-event stage, system disturbance stage, fast fault isolation stage, and remote-controlled service restoration stage are comprehensively considered and modeled in detail. Multiple resilience enhancement measures are adopted, and their coupling relationships at different stages are taken into account. In addition, an integrated energy flow model is developed to minimize the demand curtailment through coordination among different energy subsystems. The overall problem is established as a stochastic mixed-integer linear programming (MILP) model considering uncertainties of fault components. A customized progressive hedging algorithm (PHA) is further developed to reduce the computational burden caused by multiple scenarios. Case studies verify the effectiveness of the proposed model and solution technique. Simulation results reveal that the combination of multiple restoration measures is essential to reduce the impacts of EWEs, and the coordination among different energy carriers can effectively improve the resilience of the overall MESs.

Distributed transmission technology of node status in distribution network

With the rapid development of distribution network automation and the construction of DC distribution network and AC / DC hybrid distribution network, the network operation mode is more flexible. If the distribution network wants to realize rapid load transfer, such as the connection of power supply, upstream and downstream fault isolation signals and other node states need to be quickly identified. At present, the node status identification of distribution automation is basically completed by the master station. However, the master station has poor real-time transmission of status information, which is generally in seconds or minutes, and can not meet the demand of real-time load transfer. In this paper, a distributed real-time transmission method of AC and DC distribution network node status is constructed for distribution automation system. Based on IEC61850 goose communication protocol, the real-time transmission of node status is realized in distribution automation terminal. In this method, the positive direction of each tie switch is defined, which is independent of power flow direction, and the tie switch is distinguished along the user-defined positive direction When multiple tie switches have the same upstream node, they are each other’s t nodes. Each tie switch needs to be equipped with a distribution automation terminal with goose communication capability. According to different control strategies, the distribution automation terminal can realize millisecond level node state transmission step by step. Node state can be divided into unconditional transmission state and conditional transmission state. The distributed real-time transmission technology of distribution network node state proposed in this paper has been successfully applied to Tongli integrated energy service The center and Suzhou medium and low voltage DC project lay the foundation for the realization of loop closing, loop breaking control, fast fault isolation and power transfer control strategies.

Data-Driven Fault Detection and Classification for MTDC Systems by Integrating HCTSA and Softmax Regression

The requirement of fast fault isolation poses a great challenge to the safe operation of multi-terminal direct current (MTDC) systems. In order to make a better tradeoff between the speed and reliability of the protection scheme, it is imperative to mine more valuable information from fault transient signals. This paper puts forward a data-driven framework capable of digging out and synthesizing multi-dimensional features to achieve fast and reliable DC fault detection and classification in MTDC systems. Highly comparative time-series analysis (HCTSA) is first adopted to extract extensive features with clear physical interpretations from fault current waveforms, and a few features valuable to fault identification are then selected utilizing the greedy forward search. Based on the reduced features, a softmax regression classifier (SRC) is further proposed to calculate the probability of each fault category with a relatively minor on-line computational burden. Numerical simulations carried out in PSCAD/EMTDC have demonstrated the proposed approach is effective under different fault conditions, robust against noise corruptions as well as abnormal samplings, and replicable in various DC grids. In addition, comprehensive comparison studies with conventional derivative-based protection methods and some typical artificial intelligence based (AI-based) methods have been conducted. It is verified that the proposed method has the advantages of higher fault identification accuracy over conventional protections and shallow structure AI-based methods, better interpretability as well as lower on-line computing complexity over the deep architecture AI-based approaches.

Research on fast fault location and isolation strategy in Nan’ao multi-terminal VSC-HVDC

Research on fast fault location and isolation strategy in Nan’ao multi-terminal VSC-HVDC

Implementation of Resilient Self-Healing Microgrids with IEC 61850-Based Communications

Due to the high penetration of distributed energy resources (DER) and emerging DER interconnection and interoperability requirements, fast and standardized information exchange is essential for stable, resilient, and reliable operations in microgrids. This paper proposes fast fault detection, isolation, and restoration (F-FDIR) for microgrid application with the IEC 61850 Generic Object Oriented Substation Event (GOOSE) communication considering the communication/system failure. GOOSE provides a mechanism for lightweight low latency peer-to-peer data exchange between devices, which reduces the restoration time compared to conventional client-server communication paradigm. The proposed mitigation method for the communication/system failure can find an available restoration scenario and reduce the overall process time. Hardware-in-the-loop (HIL) testbed is designed and implemented with real time digital simulator, microgrid control system, and protection and control intelligent electric devices (IEDs) for the validation. The experimental results show that the proposed F-FDIR and IEC 61850 models can enhance the reliability and interoperability of the microgrid operation and enable self-healing microgrids.

DC grids DC fault detection using asymmetric pole inductors

DC fault isolation is recognized as the major obstacle against widespread development of multi-terminal meshed DC grids. To fulfill DC grid protection requirements a fast, discriminative, and seamless DC fault detection and isolation mechanism is needed. This paper presents a DC grid protection system based on using asymmetrical pole inductors (APIs) for fault detection, and hybrid DC circuit breakers (HDCCBs) for fault isolation. The pole inductors are those normally used in series with cable-end HDCCBs to limit rate of fault current development. An intentional mismatch between positive and negative poles’ inductors is proposed for autonomous fault detection using the difference between positive and negative poles’ DC voltage magnitudes measured at all cable-ends. Better accuracy in discriminative symmetrical fault detection, and less sensitivity against fault impedance are achieved using lower series inductors compared to rate of change of voltage (ROCOV) technique as the most effective approach proposed so far. In order to investigate the proposed technique, a 2 GW symmetrical monopole DC grid equipped with proposed protection system is modeled in PSCAD. Simulation results are demonstrated to show the capabilities of the proposed protection system in fast and discriminative DC fault detection.

A clamping type DC circuit breaker with short fault isolation time and low energy dissipation

The development of DC grids faces challenges from DC fault protection. The conventional DC circuit breaker (DCCB) employs metal-oxide varistor (MOV) to isolate the faulted line, in which the fault isolation process is coupled with the energy dissipation process. In this study, a clamping type DCCB (CTCB) uses internal capacitors to clamp the converter voltage is proposed. Thanks to the proposed configuration, fault isolation and energy dissipation are decoupled, resulting in a fast fault isolation and low energy dissipation compared to the conventional DCCB. The working principle of the proposed CTCB is presented and verified in a DC grid simulation model. A comparison is made with the traditional DCCB. The fault isolation time can be reduced by 34.5 %. The dissipated energy can be reduced by 17.4 %. The energy dissipation power can be reduced by 76.2 %. <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup>

Research and Application of Automatic Fault Diagnosis and Isolation Device for Distribution Line

This paper takes the equipment of a specific project as an example to develop an automatic fault diagnosis and isolation device for 10kV overhead line or cable line when a user has grounding and shortcircuit faults, so as to realize fast fault location, isolation and recovery, reduce the power outage time of users, and thus improve the reliability of distribution network. The project takes the 10kV South and North Trunk Lines ‘hand in hand’ power supply network as the research object, and studies the solutions of the automatic fault isolation function and the restoration of power supply, hoping to further improve the level of rapid power recovery, reduce power loss, and improve the reliability, automation and information level of power supply for reference.

Research on a current calculation method and characteristics of pole-to-ground faults in true bipolar MMC-HVDC grids considering line coupling✰

The pole-to-ground fault is the most common fault in the true bipolar modular multilevel converter based high voltage direct current (MMCHVDC) grid. The study of a fault current calculation method and characteristics is the theoretical basis for relay protection and fast fault isolation technology of MMCHVDC grid. Considering the mutual inductance coupling between lines, this paper proposes a general fault current calculation method for pole-to-ground faults in MMCHVDC grids. Firstly, considering the influence of AC system on MMC and the mutual inductance coupling between lines, the complex frequency domain equivalent model of the MMCHVDC grid and the simplified model of the remote converter station are studied. Based on the characteristics of the true bipolar MMCHVDC grids, the circuit is analyzed in the complex frequency domain, and an improved node voltage method combined with voltage current relation (VCR) is proposed to calculate the MMCHVDC fault current and obtain the corresponding expression. Finally, the proposed method is validated by comparing its calculation results with the simulation results performed on PSCAD/EMTDC, and the characteristics of the pole-to-ground fault in the MMCHVDC grid are further summarized.

Energy-Based Virtual Damping Control of FB-MMCs for HVDC Grid

Full-bridge submodule based modular multilevel converters (FB-MMCs) have attracted wide attention due to the DC fault blocking capability. However, the blocking of the FB-MMC can only suppress its DC terminal current while the fault currents may still circulate along the meshed DC network. To address this issue, an energy based virtual damping control is proposed, where the DC terminal current of the FB-MMC is regulated to follow the DC voltage in the event of a DC fault. The FB-MMC is thus controlled as a virtual damping resistor to actively absorb the residual energy in the DC network and quickly suppress the potential circulating DC fault currents. This enables fast fault isolation using DC switches and thereby fast fault recovery after fault isolation. The fault isolation time is significantly reduced from around 120 ms with the FB-MMC simply being blocked and 50ms with the conventional FB-MMC fault control method to around 15 ms. The validity of the proposed control is verified in a three-terminal meshed DC network.

DECENTRALIZOVANO I CENTRALIZOVANO RJEŠENJE ZA LOKACIJU I IZOLACIJU KVARA I RESTAURACIJU NAPAJANJA U PAMETNIM MREŽAMA

U ovom radu, predstavljeno je rješenje koja igra bitnu ulogu u poboljšanju pouzdanosti i povećanju kvaliteta i kontinuiteta napajanja potrošača električnom energijom – FLISR (eng. Fault Location, Isolation and Supply Restoration). FLISR ima zadatak da brzo locira i izoluje mjesto kvara i restaurira napajanje „zdravom“ dijelu mreže. Zbog toga, istraživanja o mogućim FLISR rješenjima dolaze u prvi plan u elektroenergetskim sistemima. Glavni fokus rada je na komparativnoj analizi FLISR rješenja u različitim arhitekturama, centralizovanim i decentralizovanim.

A Real-Time Resistance Based Fault Detection Technique For Zonal Type Low-Voltage DC Microgrid Applications

A fault detection method for a photovoltaic-based low-voltage dc microgrid (LV-DCMG) system is presented in this article. Unlike the conventional ac system, the dc system offers more challenges in the protection in real-time. In addition to this, many of the conventional ac protection such as distances relays, overcurrent relays, and differential relays based methods may not be used for the dc systems. This article gives more emphasis on the resistance-based fault detection for communication network less DCMG applications. The key advantages of this method are fast fault isolation, communication network less protection, good fault selectivity, better flexibility in implementation, and low protection cost. To achieve this goal, a zonal-type of dc system is considered, where the loads are connected through the dc cable and solid-state relays (SSRs) with their segmented controllers. A line-to-line short-circuit (SC) fault is introduced in the system for multiple time to check its dependability. The proposed concept has been verified by MATLAB/Simulink digital simulations and a TMS320F28335 DSP-based scaled-down LV-DCMG experimental setup. The results show that faults can be isolated from the healthy grid within a few milli second, and this isolation time is very less than the time available in the literature. A detailed study on the transient and steady-state response of the SC fault is also incorporated.