Impact of Meshed HVDC Grid Operation and Control on the Dynamics of AC/DC Systems

Hassan, Mehedi; Hossain, M. J.; Shah, Rakibuzzaman

doi:10.1109/jsyst.2020.3035379

Cited by 6 publications

(2 citation statements)

References 32 publications

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“…Stability analysis and dynamic interactions between MTDC grids and the host ac systems are presented in [17]- [19]. The work in [17] showed that interactions between an MTDC grid and ac systems are prominent following converter outages and faults on either ac or dc side, with instability often attributed to the dc-side states.…”

Section: Introductionmentioning

confidence: 99%

Analysis and Dynamic Stabilization of a High-Voltage VSC-MTDC Grid With DC Power Flow Controller Connected to Extremely Weak AC Systems

Mohamed,

El-Saadany

2024

IEEE Open J. Power Electron.

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The high-voltage voltage-source converter (VSC)based multi-terminal dc (MTDC) grid is a key technology for integrating offshore wind energy and enabling bulk power transmission across nations and continents. This paper addresses the small-signal stability of an MTDC grid equipped with a power flow controller (PFC) under extremely weak ac system interconnections. Using a comprehensive linearized state-space model, eigenvalue analysis uncovers that, beyond the welldocumented low-frequency oscillations (LFO), an MTDC grid may experience unstable medium-frequency oscillations (MFO) under rectifier operation of droop voltage-controlled VSCs when interfaced to an extremely weak ac system. Moreover, it was shown that the most challenging scenario is when multiple droop voltage-controlled VSCs are interfaced to very weak ac systems, with unstable LFO and MFO observed at short-circuit ratio values of 1.4 and 1.8, respectively. Sensitivity analysis is conducted to assess the impact of the droop voltage control gains, PFC control parameters, and dc breaker reactor on the system dominant eigenmodes in such critical weak conditions. Simple yet efficient LFO and MFO compensators are proposed to stabilize the system, and their parameters design was detailed. Extensive simulation studies and real-time validation tests verify the analytical analysis and demonstrate the effectiveness of the proposed compensators and their feasibility for real-time implementation.

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Section: Introductionmentioning

confidence: 99%

Analysis and Dynamic Stabilization of a High-Voltage VSC-MTDC Grid With DC Power Flow Controller Connected to Extremely Weak AC Systems

Mohamed,

El-Saadany

2024

IEEE Open J. Power Electron.

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“…The associate editor coordinating the review of this manuscript and approving it for publication was Nagesh Prabhu . complex topologies, (i.e., meshed topologies) are yet to overcome [5]. The absence of zero-crossing fault current in a low impedance DC path poses a major threat to the DC protection scheme and thereby, treated as one of the significant concerns.…”

Section: Introductionmentioning

confidence: 99%

DC Fault Identification in Multiterminal HVDC Systems Based on Reactor Voltage Gradient

2021

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With the increasing number of renewable generations, the prospects of long-distance bulk power transmission impels the expansion of point-to-point High Voltage Direct Current (HVDC) grid to an emerging Multi-terminal high-voltage Direct Current (MTDC) grid. The DC grid protection with faster selectivity enhances the operational continuity of the MTDC grid. Based on the reactor voltage gradient (RVG), this paper proposes a fast and reliable fault identification technique with precise discrimination of internal and external DC faults. Considering the voltage developed across the modular multilevel converter (MMC) reactor and DC terminal reactor, the RVG is formulated to characterise an internal and external DC fault. With a window of four RVG samples, the fault is detected and discriminated by the proposed main protection scheme amidst a period of five sampling intervals. Depending on the reactor current increment, a backup protection scheme is also proposed to enhance the protection reliability. The performance of the proposed scheme is validated in a four-terminal MTDC grid. The results under meaningful fault events show that the proposed scheme is capable to identify the DC fault within millisecond. Moreover, the evaluation of the protection sensitivity and robustness reveals that the proposed scheme is highly selective for a wide range of fault resistances and locations, higher sampling frequencies, and irrelevant transient events. Furthermore, the comparison results exhibit that the proposed RVG method improves the discrimination performance of the protection scheme and thereby, proves to be a better choice for future DC fault identification.

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Transient characteristics and protection coordination strategy of hybrid AC / DC system based on modular multilevel converters under AC/DC transmission lines touching fault

Impact of Meshed HVDC Grid Operation and Control on the Dynamics of AC/DC Systems

Cited by 6 publications

References 32 publications

Analysis and Dynamic Stabilization of a High-Voltage VSC-MTDC Grid With DC Power Flow Controller Connected to Extremely Weak AC Systems

Analysis and Dynamic Stabilization of a High-Voltage VSC-MTDC Grid With DC Power Flow Controller Connected to Extremely Weak AC Systems

DC Fault Identification in Multiterminal HVDC Systems Based on Reactor Voltage Gradient

Transient characteristics and protection coordination strategy of hybrid AC / DC system based on modular multilevel converters under AC/DC transmission lines touching fault

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