scholarly journals A Fast DC Fault Detection Method for Multi-Terminal AC/DC Hybrid Distribution Network Based on Voltage Change Rate of DC Current-Limiting Inductor

Energies ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1828 ◽  
Author(s):  
Xiaomin Qi ◽  
Wei Pei ◽  
Luyang Li ◽  
Li Kong
Keyword(s):  
Fault Detection ◽  
Detection Method ◽  
Distribution Network ◽  
Distribution Networks ◽  
Change Rate ◽  
Fault Type ◽  
Dc Fault ◽  
Voltage Change ◽  
Current Limiting ◽  
Hybrid Distribution

The rapid detection of direct current (DC) faults is one of the key technologies for the development of multi-terminal alternating current (AC)/DC hybrid distribution networks. The DC fault current rises quickly and affects the whole network. Therefore, DC faults must be detected much faster than AC faults. This paper proposes a fast DC fault detection method based on the voltage change rate of the current-limiting inductor (CLI) for the multi-terminal AC/DC hybrid distribution network. Firstly, the characteristics of the fault voltages and currents and of the CLIs are studied in detail, and the feasibility of using the voltage change rate of the CLI to detect DC fault is analyzed. Based on this, a primary fault detection method is proposed to identify the faulty line, determine the fault type and the fault poles using the amplitudes of the single-ended CLI voltage change rates. For high-resistance DC faults, a backup detection method using the directions and amplitudes of the voltage change rates of the double-ended CLIs is proposed. Finally, the proposed method is verified by MATLAB simulations. The simulation results show that the proposed method can detect all DC faults accurately, and the faulty line, fault type and fault poles can be determined quickly. The proposed method is not affected by the fault location, current-limiting inductance, power reversal of the converters, AC fault and communication delay.

scholarly journals FLISR Approach for Smart Distribution Networks Using E-Terra Software—A Case Study

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3333 ◽  
Author(s):  
Duy Le ◽  
Duong Bui ◽  
Cao Ngo ◽  
Anh Le
Keyword(s):  
Fault Detection ◽  
Management System ◽  
Processing Time ◽  
Distribution Network ◽  
Data Communication ◽  
Distribution Networks ◽  
Fault Isolation ◽  
Service Restoration ◽  
Minimum Number ◽  
Terminal Units

A smart grid concept has been defined in recent years, which emphasizes the importance on smart protection and measurement devices, reliable data communication and high security, optimal energy management system, and fault detection, location, isolation and service restoration (FLISR) of distribution networks (DNs). The main objectives of the FLISR approach are to achieve fast fault processing time, reduce the minimum number of interrupted customers, and improve the power supply reliability of the distribution. The conventional FLISR approach is to use signals of fault indicators (FIs) with distribution network states. The discrete installation of FIs to switches or reclosers may slow the processing time of fault detection and location, so it is necessary to develop a more efficient FLISR approach for smart distribution networks using functions of feeder terminal units (FTUs). In this paper, pick-up and tripping signals of overcurrent (OC) relays in combination with distribution grid states (e.g., switching status of devices, loss of voltage…) sent from feeder terminal units (FTUs) are used to detect and locate different fault types. Fault isolation and service restoration of black-out areas are then performed by solving an objective function with two main constraints, including (i) restoring the possible maximum number of out-of-service loads; and (ii) limiting the minimum number of switching operation. Thirteen performance factors (PF) are used for the post-fault service restoration process, consisting of: (i) Power Flow Violations (PFV), (ii) Bus Voltage Violations (BVV), (iii) Total Operation Cost (TOC), (iv) Lost Power (LP), (v) Outage Customer (OC), (vi) Number of Switching Steps (NSS), (vii) Power Losses (LOSS); (viii) Customer Minutes Interruption (CMI), (ix) Load Minutes Interruption (LMI), (x) MAIFI, (xi) SAIFI, (xii) SAIDI, and (xiii) Protection Validation (PRV). E-Terra platform of a distribution management system (DMS) is used to implement the proposed FLISR approach. Simulation and experiment results from a real 22 kV distribution network are also analysed to validate this FLISR approach. As a result, the novel FLISR approach has the ability to identify effectively the over-reaching of OC relays, indicate a mis-coordination risk of adjacent protection devices on the same feeder, and get the total processing time of fault detection, location and isolation as well as ranking all possible service restoration plans in distribution network at less than two minutes.

scholarly journals Research on the Structure and Control Strategy of a Novel Power Electronic Transformer for AC/DC Hybrid Distribution Network

2019 ◽  
Vol 9 (4) ◽  
pp. 727 ◽  
Author(s):  
Jingguo Rong ◽  
Xin Ai ◽  
Yunning Li ◽  
Dapeng Ren
Keyword(s):  
Control Strategy ◽  
Control Method ◽  
Distribution Network ◽  
Distribution Networks ◽  
Frequency Regulation ◽  
Power Electronic ◽  
Output Stage ◽  
Hybrid Distribution ◽  
And Control ◽  
Virtual Synchronous Machine

Power electronic transformers (PETs), as the core devices of the energy internet, are the key to achieve both effective consumption for renewable energy and the safe and coordinated operation for AC/DC hybrid system. In order to overcome the shortcomings of the existing PETs, a novel PET with an improved structure that applicable for multi-voltage level AC/DC hybrid distribution network is proposed. The topology of the proposed PET is analyzed, and the corresponding control methods are suggested for different parts. The input stage utilizes the modular multilevel converter structure and applies the virtual synchronous machine control strategy to enhance the inertia and damping of the system. The power of the output stage is adjusted flexibly and that enables the PET to provide certain power support to the upper grid and participate in its primary frequency regulation. A combined connection of input-series output-series and input-series output-parallel is applied for the dual-active-bridge modules of the isolation stage to enable network interconnection and electrical isolation of AC/DC grids with significantly different voltage levels. A power coordinated control method is then proposed to meet the power demand of the distribution networks connected to the output stage and ensure stable operations of PET simultaneously. The reliability and efficiency of the proposed PET topology and control strategy for AC/DC hybrid distribution network are finally verified via PSCAD/EMTDC simulation.

Fault-tolerant relative navigation based on Kullback–Leibler divergence

2020 ◽  
Vol 17 (6) ◽  
pp. 172988142097912
Author(s):  
Jun Xiong ◽  
Joon Wayn Cheong ◽  
Zhi Xiong ◽  
Andrew G Dempster ◽  
Shiwei Tian ◽  
...  
Keyword(s):  
Kalman Filter ◽  
Fault Detection ◽  
Detection Method ◽  
Fault Tolerant ◽  
Relative Navigation ◽  
Fusion Procedure ◽  
Leibler Divergence ◽  
F Distribution ◽  
Hybrid Distribution ◽  
Exclusion Method

A fault-detection method for relative navigation based on Kullback–Leibler divergence (KLD) is proposed. Different from the traditional χ 2-based approaches, the KLD for a filter is following a hybrid distribution that combines χ 2 distribution and F-distribution. Using extended Kalman filter (EKF) as the estimator, the distance between the priori and posteriori data of EKF is calculated to detect the abnormal measurements. After fault detection step, a fault exclusion method is applied to remove the error observations from the fusion procedure. The proposed method is suitable for the Kalman filter-based multisensor relative navigation system. Simulation and experimental results show that the proposed method can detect the abnormal measurement successfully, and its positioning accuracy after fault detection and exclusion outperforms the traditional χ 2-based method.

A Fast DC Fault Detection Method Using DC Reactor Voltages in HVdc Grids

2018 ◽  
Vol 33 (5) ◽  
pp. 2254-2264 ◽  
Author(s):  
Chengyu Li ◽  
Aniruddha M. Gole ◽  
Chengyong Zhao
Keyword(s):  
Fault Detection ◽  
Detection Method ◽  
Dc Reactor ◽  
Dc Fault

scholarly journals A High-Speed Fault Detection, Identification, and Isolation Method for a Last Mile Radial LVDC Distribution Network

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2901 ◽  
Author(s):  
Saeed Jamali ◽  
Syed Bukhari ◽  
Muhammad Khan ◽  
Khawaja Mehmood ◽  
Muhammad Mehdi ◽  
...  
Keyword(s):  
Fault Detection ◽  
High Speed ◽  
Power Flow ◽  
Detection Method ◽  
Distribution Network ◽  
Test System ◽  
Detection And Identification ◽  
Fault Detection And Identification ◽  
Simulation Results ◽  
Vector Sum

The day-by-day increase in digital loads draws attention towards the need for an efficient and compatible distribution network. An LVDC distribution network has the capability to fulfill such digital load demands. However, the major challenge of an LVDC distribution network is its vulnerability during a fault. The need for a high-speed fault detection method is inevitable before it can be widely adopted. This paper proposes a new fault detection method which extracts the features of the current during a fault. The proposed fault detection method uses the merits of overcurrent, the first and second derivative of current, and signal processing techniques. Three different features are extracted from a time domain current signal through a sliding window. The extracted features are based upon the root squared zero, second, and fourth order moments. The features are then set with individual thresholds to discriminate low-, high-, and very high-resistance faults. Furthermore, a fault is located through the superimposed power flow. Moreover, this study proposes a new method based on the vector sum of positive and negative pole currents to identify the faulty pole. The proposed scheme is verified by using a modified IEEE 13 node distribution network, which is implemented in Matlab/Simulink. The simulation results confirm the effectiveness of the proposed fault detection and identification method. The simulation results also confirm that a fault having a resistance of 1 m Ω is detected and interrupted within 250 μ s for the test system used in this study.

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