Abstract
Accurate and reliable fault location method for alternating current (AC) transmission lines is essential to the fault recovery. MMC-based converter brings exclusive non-linear characteristics to AC networks under single-phase-to-ground faults, thus influencing the performance of the fault location method. Fault characteristics are related to the control strategies of the converter. However, the existing fault location methods do not take the control strategies into account, with further study being required to solve this problem. The influence of the control strategies to the fault compound sequence network is analyzed in this paper first. Then, a unique boundary condition that the fault voltage and negative-sequence fault current merely meet the direct proportion linear relationship at the fault point, is derived. Based on these, a unary linear regression analysis is performed, and the fault can be located according to the minimum residual sum function principle. The effectiveness of the proposed method is verified by PSCAD/EMTDC simulation platform. A large number of simulation results are used to verify the advantages on sampling frequency, fault resistance, and fault distance. More importantly, it provides a higher ranging precision and has extensive applicability.
Highlights
Modular multilevel converter-based high voltage direct current (MMC-HVDC) plays an increasingly important role in the field of renewable energy integration and regional power grid interconnection, due to its outstanding advantages in having no commutation failure, flexible control, and superior harmonic performance [1]
A novel single-terminal fault location method considering the influence of the control strategies to the fault compound sequence network was proposed in this paper
It is based on the unique boundary condition at the fault point provided by the negative-sequence current restraint strategy of the converter
Summary
Modular multilevel converter-based high voltage direct current (MMC-HVDC) plays an increasingly important role in the field of renewable energy integration and regional power grid interconnection, due to its outstanding advantages in having no commutation failure, flexible control, and superior harmonic performance [1]. The world’s first ± 500 kV four-terminal MMC-HVDC demonstration project is currently under construction in Zhangbei, China, which is attracting more research interest in direct current (DC) short-circuit faults. The single-phase-to-ground fault is one that happens frequently in AC transmission line, and the short-circuit current will seriously affect the safety and stability of the system. The fault transient characteristics of the MMC-based converters in AC sides are influenced by the control strategies, which will cause some difficulties for locating fault [3]
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