Review of DC fault protection for HVDC grids

Li, Rui; Xu, Lie

doi:10.1002/wene.278

Cited by 22 publications

(24 citation statements)

References 61 publications

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“…MMC 1, 2 and 3 and OWF 1. It is worth underscoring that the onshore stations MMC 1 and 2 are protected by DCCBs plus DC inductors, which help the arm currents of these MMCs to remain below 2 pu (1 pu current is 2 kA) during the fault and thus remain operational without blocking [12,31] as shown in Fig. 8 (a).…”

Section: A Fault Clearancementioning

confidence: 99%

“…This leads to the rapid rise of the fault currents. Once the arm current exceeds 2 pu [12,31], MMC 4 is blocked at 2.0015 s and the offshore AC network voltage is also collapsed, as shown in Fig. 10 (b), (c) and Fig.…”

Section: A Fault Clearancementioning

confidence: 99%

“…DC fault protection is a major technical obstacle that prevents the development of reliable MTDC grids and has drawn significant attention from academia and industry [10][11][12]. Several protection concepts have been proposed to facilitate fault isolation in offshore MTDC networks.…”

Section: Introductionmentioning

confidence: 99%

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Enhanced Control of Offshore Wind Farms Connected to MTDC Network Using Partially Selective DC Fault Protection

Shi

Adam

et al. 2021

IEEE J. Emerg. Sel. Topics Power Electron.

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In recent years, several DC fault clearance schemes have emerged, in which reduced number of fast acting DC circuit breakers (DCCBs) and AC circuit breakers (ACCBs) are used to clear DC faults. In offshore DC grids, such approach entails opening of the ACCBs that connect the wind farms to the offshore HVDC stations which control offshore AC voltages and frequencies, potentially leading to uncontrolled offshore voltage and frequency. Existing studies show that the loss of offshore converter due to blocking or sudden opening of ACCBs can cause significant over-voltage and over-frequency in the offshore AC grid, which could necessitate immediate shutdown of the wind farm. An enhanced control for wind turbine converters (WTCs) of the offshore wind farm is proposed to enable retention of AC voltage and frequency control when the offshore converter is lost, in which seamless transition of the WTCs between grid following and forming modes is facilitated. The viability of the proposed control is demonstrated in wider context of partially selective DC fault protection in an illustrative meshed DC grid, which includes detailed implementations of DC fault clearance, system restart and power transfer resumption. The presented simulation results confirm the effectiveness of the proposed WTC control in preventing excessive rise of offshore AC voltage and frequency and facilitating DC fault ride-through using reduced number of DCCBs.

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Section: A Fault Clearancementioning

confidence: 99%

Section: A Fault Clearancementioning

confidence: 99%

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Enhanced Control of Offshore Wind Farms Connected to MTDC Network Using Partially Selective DC Fault Protection

Shi

Adam

et al. 2021

IEEE J. Emerg. Sel. Topics Power Electron.

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“…Then, they are inherently selective (Marten et al, 2016), but they depend on the communication channel medium and the time delay imposed by it. This communication time delay can make the protection system not capable of meeting the requirement of speed (Li and Xu, 2018), even if the optical fiber is used, which presents a time delay of 1 ms per 200 km (Dallas and Booth, 2014). Consequently, the communication time delay is the most limiting parameter in the operation time of a communication-based algorithm (Pérez-Molina et al, 2019).…”

Section: Protection Algorithmsmentioning

confidence: 99%

Challenges for Protection of Future HVDC Grids

et al. 2020

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Nowadays, High Voltage Direct Current (HVDC) transmissions are gaining relevance in long distance and renewable energy integration projects over the conventional Alternating Current (AC) transmissions due to several advantages as improved flexibility and independent active and reactive power controllability. Despite that, the high currents and voltage collapses generated by fault conditions in HVDC systems imply some unresolved technical challenges regarding the detection, location and clearance of faults. Faults have to be cleared in a very short time range in order to minimize their impact on the system. For this objective, very fast protection algorithms and reliable HVDC circuit breakers are required. This paper focuses on the technical challenges and limitations of HVDC protection systems. This way, protection requirements and different types of measurement devices are considered. Protection algorithms are classified into local-measurement-based and communication-based, highlighting the most important characteristics. In addition, the different technologies of HVDC circuit breakers are compared. Finally, the characteristics and effects of the different available fault-clearing strategies are presented.

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“…Although the MMC-HVDC technology has achieved a high degree of maturity, system protection and fault tolerant operation remain as outstanding challenges [8]- [9]. However, significant research has been conducted in these areas to facilitate its widespread deployment.…”

Section: Introductionmentioning

confidence: 99%

Protection for Submodule Overvoltage Caused by Converter Valve-Side Single-Phase-to-Ground Faults in FB-MMC Based Bipolar HVDC Systems

Liang

Ugalde‐Loo

et al. 2020

IEEE Trans. Power Delivery

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One of the most critical faults affecting modular multilevel converter (MMC) based bipolar high-voltage directcurrent (HVDC) transmission systems is the single-phase-toground (SPG) faults between the converter transformer and the valve. However, half-bridge (HB) and full-bridge (FB) based MMCs exhibit a different behavior following such a fault and, thus, converter protection should be addressed in a different manner for each configuration. For HB-MMCs, an SPG fault at the valve-side leads to a severe overvoltage on the submodule (SM) capacitors in the converter upper arms and to grid-side non-zero crossing currents. Although FB-MMCs only exhibit overvoltage, these are more severe than for their HB counterparts. To address this problem, this paper presents a protection strategy considering thyristor bypass branches placed in parallel with upper arms of FB-MMCs. By employing this configuration, the upper arm overvoltage in the faulted converter is mitigated and remote converters can be quickly blocked using their local protection schemes. For completeness, the effectiveness of the strategy is verified through time-domain simulations in PSCAD/ EMTDC. The studies in this paper demonstrate the effectiveness of the presented protection scheme for station internal faults occurring in FB-MMCs in bipolar HVDC systems.

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Review of DC fault protection for HVDC grids

Cited by 22 publications

References 61 publications

Enhanced Control of Offshore Wind Farms Connected to MTDC Network Using Partially Selective DC Fault Protection

Enhanced Control of Offshore Wind Farms Connected to MTDC Network Using Partially Selective DC Fault Protection

Challenges for Protection of Future HVDC Grids

Protection for Submodule Overvoltage Caused by Converter Valve-Side Single-Phase-to-Ground Faults in FB-MMC Based Bipolar HVDC Systems

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