Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Synchronization Stability Analysis and Enhancement of Grid-Tied
  Multi-Converter Systems   Synchronization instability of grid-tied converters during grid faults is a
serious concern. For phase-locked loop (PLL) synchronized converters,
synchronization stability during grid faults requires that PLL can
resynchronize with the power grid. It is of great significance for meeting grid
code specifications such as reactive current support. However, the
synchronization in the context of high-impedance weak grid is not always
readily achieved. On one hand, the terminal voltage of converters is changeable
due to being susceptible to the output current. One the other hand, there is
interaction between multiple converters interconnected to the grid. Therefore,
loss of synchronism (LOS) of converters during grid faults likely occurs.
Previous research has investigated the LOS issue of single-converter
infinite-bus (SCIB) system, but mostly overlooked the interaction between
multiple converters. Previous efforts to address the issue of LOS are also in
doubt for multi-converter systems. This paper develops a multi-converter
infinite-bus (MCIB) system model and analyzes the root cause of LOS with
considering multi-converter interaction during grid faults. Moreover, a
feedforward compensated PLL (FFC-PLL) method applicable for multi-converter
systems is developed to address the LOS issue. Simulations results verify the
effectiveness of the method.

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The categories of this paper are: nucl-ex
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The categories of this paper are: q-alg
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The categories of this paper are: atom-ph
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The categories of this paper are: stat
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The categories of this paper are: math-ph
6
The categories of this paper are: astro-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: chem-ph
2
The categories of this paper are: math
5
The categories of this paper are: gr-qc
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The categories of this paper are: nucl-th
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The categories of this paper are: acc-phys
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The categories of this paper are: econ
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The categories of this paper are: plasm-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: dg-ga