A Pole-to-Pole Short-Circuit Fault Current Calculation Method for DC Grids

Li, Chengyu; Zhao, Chengyong; Xu, Jianzhong; Ji, Yuke; Zhang, Fan; An, Ting

doi:10.1109/tpwrs.2017.2682110

Cited by 218 publications

(107 citation statements)

References 26 publications

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“…The pole to pole (PTP) faults and pole to ground (PTG) faults are two common faults on the DC transmission lines. The analysis and calculation of fault currents have been presented in [4] and [27] in detail. When a PTP fault occurs, the DC terminal voltage of the faulted line drops to zero quickly and the fault line current increases drastically.…”

Section: A Topology Of a Four-terminal MMC Based Dc Gridmentioning

confidence: 99%

“…With the increased need for renewable energy utilization and resource optimization, the modular multilevel converter (MMC) based DC grid has been a competitive candidate to integrate bulk renewable energy over long distance [1]- [3]. Different to the two-terminal HVDC systems, in a DC grid, multiple converters will feed fault currents to the faulted lines during DC faults, leading to high over-currents [4]. For the safe operation and avoiding the shutdown of the entire DC grid, it is desirable to use high-power DC circuit breakers (DCCB) to isolate the fault lines within a short period of time, e.g.…”

Section: Introductionmentioning

confidence: 99%

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A Transient Voltage-Based DC Fault Line Protection Scheme for MMC-Based DC Grid Embedding DC Breakers

Xiang

Yang

et al. 2019

IEEE Trans. Power Delivery

203

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Abstract-Fast and reliable DC fault detection is one of the main challenges for modular multilevel converter (MMC) based DC grid with DC circuit breakers (DCCBs). This paper extracts the high frequency components of transient voltages by wavelet transform and proposes a fault identification method based on the difference of transient voltages to identify the faulted lines for DC grids using overhead lines. Meanwhile, a faulted pole discrimination method based on the difference between the change of positive and negative pole voltages is presented. A line protection scheme including detection activation, fault identification, faulted pole discrimination and post-fault re-closing is designed. Using only the local measurements, the scheme can realize the protection of the whole line without communication and has the capability of fault resistance endurance and anti-disturbance. The proposed method is tested with a four-terminal MMC based DC grid in PSCAD/EMTDC. The selection methods of threshold values are presented and the impact of DCCB operation on the reliability of DC fault protection is analysed. Simulation results verify the fast detection and reliability of the designed DC line protection scheme. Index Terms-DC fault protection, fault identification, transient voltage, hybrid DC breaker, modular multilevel converter (MMC), post-fault re-closing.This paper is a post-print of a paper submitted to and accepted for publication in IEEE Transaction on Power Delivery and is subject to Institution of Electrical and Electronic Engineering

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Section: A Topology Of a Four-terminal MMC Based Dc Gridmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Transient Voltage-Based DC Fault Line Protection Scheme for MMC-Based DC Grid Embedding DC Breakers

Xiang

Yang

et al. 2019

IEEE Trans. Power Delivery

203

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“…The impact of AC source on fault current can be ignored [18]. Referring to [19], the simplified equivalent model of MMC can be obtained, as shown in Fig. 2…”

Section: A Equivalent Model Of Half-bridge MMCmentioning

confidence: 99%

An Improved DC Fault Protection Algorithm for MMC HVDC Grids Based on Modal-Domain Analysis

Yang

Xiang

et al. 2020

IEEE J. Emerg. Sel. Topics Power Electron.

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Abstract-To detect the DC faults for MMC based DC grids using overhead line transmission, many protection methods in phase-domain have been proposed. These existing protection methods suffer from incomplete function, weak theoretical basis and sensitivity to fault resistance and noise disturbance. To overcome these shortcomings, this paper proposes an improved DC fault protection algorithm using the modal-domain approach for the MMC based overhead DC grids, which decouples interaction between positive and negative poles and mitigates the strong frequency-dependency of the characteristic impedance in phase-domain. The DC fault equivalent circuits are established in modal-domain and the fault characteristics during the initial stage are analysed. Based on the modal-domain analysis, the line-mode reactor voltage which combines fault characteristics of negative and positive reactor voltages, is employed to identify the internal faults. The zero-mode reactor voltage which enlarges the differences between faulty and healthy poles, is employed to select the faulted pole. This method is robust to fault resistance and noise with high detection speed. In addition, it is not affected by power reversal, AC faults and DCCB operation, which are validated and evaluated by simulations in PSCAD/EMTDC.

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“…Meanwhile the DCCB model is not considered in the whole calculation and analysis process. Li, C [29] deduces the mathematical modeling of the multi-terminal flexible DC system based on MMC, and the current analytical formula of the multi-terminal flexible DC system under the pole-to-pole short circuit fault is derived. Although the transient stability analysis of the DC system with DCCB under the short circuit fault is mentioned in the simulation, the detailed mathematical model and combined calculation process of the DC circuit breaker are not given.…”

Section: Introductionmentioning

confidence: 99%

Short-Circuit Fault Current Calculation Method for the Multi-Terminal DC Grid Considering the DC Circuit Breaker

et al. 2020

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The analysis and calculation of the short-circuit fault current in the DC grid is of great significance to the design and configuration of the converter station and DC circuit breaker parameters. The existing flexible DC system not only includes the modular multilevel converter (MMC) converter, but also needs power equipment such as the fault current limiter and DC circuit breaker. Therefore, the system modeling and short circuit calculation of the multi-terminal DC system after adding the DC circuit breaker are also of great significance for the design of DC power system parameters and the grid troubleshooting ability. In this paper, firstly, the parameters of the four-terminal DC system of the modular multilevel converter (MMC) are simplified, and the analytical solution of the short circuit fault current of the multi-terminal DC system is given. Then, the external characteristics of the cascaded hybrid DC circuit breaker are modeled. Based on the equivalent circuit of the fault current in different stages, the short circuit calculation method of four-terminal MMC system with DC circuit breaker is obtained. This method can effectively describe the overall trend of fault current and provide the basis for the configuration of DC line protection settings and DC circuit breaker related parameters.

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A Pole-to-Pole Short-Circuit Fault Current Calculation Method for DC Grids

Cited by 218 publications

References 26 publications

A Transient Voltage-Based DC Fault Line Protection Scheme for MMC-Based DC Grid Embedding DC Breakers

A Transient Voltage-Based DC Fault Line Protection Scheme for MMC-Based DC Grid Embedding DC Breakers

An Improved DC Fault Protection Algorithm for MMC HVDC Grids Based on Modal-Domain Analysis

Short-Circuit Fault Current Calculation Method for the Multi-Terminal DC Grid Considering the DC Circuit Breaker

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