Fault Current Estimation in Multi-Terminal HVdc Grids Considering MMC Control

Langwasser, Marius; Carne, Giovanni De; Liserre, Marco; Biskoping, Matthias

doi:10.1109/tpwrs.2018.2887166

Cited by 66 publications

(36 citation statements)

References 25 publications

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“…The KVL and KCL equations for the circuit shown in Fig. 11 could be derived as shown in (18) and (19).…”

Section: Figure 11 Simplified Model Between Any Two Adjacent Nodesmentioning

confidence: 99%

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An Equivalent Calculation Method for Pole-to-Ground Fault Transient Characteristics of Symmetrical Monopolar MMC Based DC Grid

Zhang

et al. 2020

IEEE Access

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The pole-to-ground fault is one of the most typical faults in modular multilevel converters (MMCs) based DC grid. Analyzing the transient characteristics of fault voltages and currents is of great significance for fault identification, configuration of protection, and optimization of system parameters. This paper proposes an equivalent transient characteristics calculation method for pole-to-ground faults for symmetrical monopolar MMC based DC grid. Firstly, according to the mechanism of the pole-to-ground faults, the fault network and the steady-state network are formed. Then, the star-delta transformation is performed on modelling the MMCs in the fault network, which overcomes the problem that the number of the inserted sub-modules (SMs) in each arm is time-variant. Based on the discrete adjoint model, the prefault and faulted matrices describing the voltages and currents are established, and a general method for solving the transient voltages and currents is proposed. Finally, the proposed method is validated in a fourterminal symmetrical monopolar MMC based DC grid. The results show that the proposed method is of high accuracy, and is much more time efficient than time-domain simulation. INDEX TERMS Modular multilevel converter (MMC), symmetrical monopolar, DC grid, pole-to-ground fault, discrete adjoint model, voltage and current characteristics

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“…The KVL and KCL equations for the circuit shown in Fig. 11 could be derived as shown in (18) and (19).…”

Section: Figure 11 Simplified Model Between Any Two Adjacent Nodesmentioning

confidence: 99%

“…Based on the state variable analysis method, [17] and [18] calculate the fault currents in a DC grid by solving the differentialalgebraic equations. In [19], the model of MMCs has been modified by taking the controllers into account, and thus the accuracy is improved.…”

Section: Introductionmentioning

confidence: 99%

An Equivalent Calculation Method for Pole-to-Ground Fault Transient Characteristics of Symmetrical Monopolar MMC Based DC Grid

Zhang

et al. 2020

IEEE Access

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“…High voltage direct current (HVDC) transmission technology is an efficient approach to deliver bulk renewable power over long distance [1] [2]. As the increased commission of line-commutated converter (LCC) based HVDC projects, two or more HVDC links tend to feed into one regional power grid and form a multi-infeed HVDC system, such as the East China Power Grid and the Southern China Power Grid.…”

Section: Introductionmentioning

confidence: 99%

A Cascaded Converter Interfacing Long-Distance HVdc and Back-to-Back HVdc Systems

Xiang

Ren-gang

Chang

et al. 2020

IEEE J. Emerg. Sel. Topics Power Electron.

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Abstract-This paper proposes a cascaded converter dedicated to long-distance HVDC infeed and asynchronous back-to-back interconnection of receiving grids. The cascaded converter is consisted of MMCs in series and parallel connection, meeting the high DC voltage and power demand of HVDC system. It realizes hierarchical feeding and asynchronous interconnection of receiving grids, optimizing the multi-infeed short circuit ratio and improving the flexibility of the receiving grids. The topology and operating characteristics of the cascaded converter are introduced in detail. The multi-infeed short-circuits ratio (MISCR) and the maximum power infeed of the cascaded converter based HVDC systems are analyzed. Various feasible operating modes with online switching strategies of the cascaded converter are studied to improve the operational flexibility of the system. The simulation results verify the effectiveness of the control strategy of the HVDC system embedding the cascaded converter. The DC faults clearing strategy and operating modes switching strategies are also validated.

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“…Until now, no research about pole‐to‐ground fault current calculation in symmetrical monopole DC grids has been reported, not to mention considering the control mode influence. Actually, the control's influence to pole‐to‐pole fault cannot be ignored as proved in [3]. Thus, the pole‐to‐ground fault current estimation should also consider the impact of control, as the equivalent circuit and fault path of pole‐to‐ground fault are quite different from the pole‐to‐pole fault.…”

Section: Introductionmentioning

confidence: 99%

“…Influence of MMC control on pole-to-ground fault: The following part will study how to add control modes into the above fault current calculation equations. Actually, a control current source can be added to reflect the MMC control effect [3], as Fig. 3 shows.…”

mentioning

confidence: 99%

Pole‐to‐ground fault current estimation in symmetrical monopole high‐voltage direct current grid considering modular multilevel converter control

Yan

Liu

2020

Electron. lett.

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This Letter proposed a novel method to accurately estimate the pole-toground fault current in symmetrical monopole high-voltage direct current grids. To avoid simulation's time consuming and difficult modelling, the converter is equivalent to the simple resistor LC circuit, and the state space including negative pole and positive pole is established for pole-to-ground current estimation. To enhance the accuracy of the estimation, the influence of converter control is considered in the estimation. It is found that the dc voltage control mode would impact the fault current rather than the power control mode. In addition, the accuracy can be improved a lot when the control is taken into consideration in fault current estimation. The simulations validate the proposed method finally.

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Fault Current Estimation in Multi-Terminal HVdc Grids Considering MMC Control

Cited by 66 publications

References 25 publications

An Equivalent Calculation Method for Pole-to-Ground Fault Transient Characteristics of Symmetrical Monopolar MMC Based DC Grid

An Equivalent Calculation Method for Pole-to-Ground Fault Transient Characteristics of Symmetrical Monopolar MMC Based DC Grid

A Cascaded Converter Interfacing Long-Distance HVdc and Back-to-Back HVdc Systems

Pole‐to‐ground fault current estimation in symmetrical monopole high‐voltage direct current grid considering modular multilevel converter control

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