Adaptability Analysis of Fault Component Distance Protection on Transmission Lines Connected to Photovoltaic Power Stations

Photovoltaic (PV) power plants have comparatively weak infeed characteristics, unlike conventional synchronous generators. The controllability of grid-connected inverters and the limited overcurrent capability of power electronic devices means that the characteristics of faults on transmission lines fed by PV power stations are substantially different than those on transmission lines fed by conventional sources. Operating performances of distance relays on PV-fed transmission line are unveiled. This paper analyses the impact of PV-fed transmission lines in infeed conditions on distance protection. Fault signals on the transmission line were generated by Digsilent PowerFactory software. Then, fault signals were analyzed by discrete Fourier transformation (DFT) with MATLAB software. The measured current and voltage signals were preprocessed first with DFT, and then machine learning via a support vector machine (SVM) was used for regression. This research proposes an improvement on distance protection with SVM for preventing maloperation in infeed conditions on PV fed transmission lines. The average accuracy was up to 95.6% in this study. The simulation was performed at different locations along the transmission line with different types of fault on a given power system model with the PV power plant.

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Performance Problem of Current Differential Protection of Lines Emanating from Photovoltaic Power Plants

Liang

2020

Sustainability

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The amplitude and phase angle of the fault current in photovoltaic power plants (PVPPs) are significantly influenced by the control system of the grid-connected inverters, unlike in a conventional synchronous source. Hence, PVPPs may adversely affect the performance of the current differential protection designed for synchronous sources-based power grids. In order to study the performance problem of current differential protection on AC transmission lines, an analytical expression of the fault current in the PVPPs was deduced, and the fault current characteristic was extensively analyzed. Based on this analysis, the ratio of differential current over restraint current was initially derived in this study; this ratio is observed to be affected by the control system parameters, power grid system parameters, fault resistance, and fault types. Moreover, the dynamic characteristics of this ratio can be clearly observed based on a three-dimensional diagram. Furthermore, the operating performance of the current differential protection was analyzed under different influencing factors. The mathematical analysis presents that the amplitude ratio of the fault current on both sides of the line is larger than nine and that current differential protection will operate reliably in any case. Meanwhile, the theoretical analysis and simulation results show that the current phase angle difference may become an obtuse angle in case of an ungrounded fault, which will cause inaccurate operation of the current differential protection. The results of this study will provide guidance for the engineering application of current differential protection in case the PVPPs are connected to a power grid.

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Adaptability Analysis of Fault Component Distance Protection on Transmission Lines Connected to Photovoltaic Power Stations

Cited by 3 publications

References 26 publications

A novel protection scheme for transmission lines connected to solar photovoltaic and wind turbine farms using fuzzy logic systems and bagged ensemble learning

A novel protection scheme for transmission lines connected to solar photovoltaic and wind turbine farms using fuzzy logic systems and bagged ensemble learning

Improvement of Distance Protection with SVM on PV-Fed Transmission Lines in Infeed Conditions

Performance Problem of Current Differential Protection of Lines Emanating from Photovoltaic Power Plants

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