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Coordinated Grid-Forming Controller for Solid-State Transformer-Enabled PV Farms

2023; Institute of Electrical and Electronics Engineers; Volume: 38; Issue: 4 Linguagem: Inglês

10.1109/tec.2023.3291661

1558-0059

Mahmoud A. Elshenawy, Amr Radwan, Yasser Abdel‐Rady I. Mohamed,

Islanding Detection in Power Systems

Grid-forming solid-state transformer (GFm-SST) is an emerging technology in modernized power grids that delivers the merits of SSTs and GFm control, thus, providing a compact, controllable, and grid-supporting means of renewable resources integration. This article presents a comprehensive and coordinated GFm controller for two-stage SST-interfaced solar photovoltaic (PV) systems. The controllers of both SST stages are coordinated, and a virtual governor is implemented within the coordinated reference generation stage so that the PV power directly interacts with grid-side frequency events while preserving minimal dc voltage variations. A bandgap ac voltage controller is proposed to ensure accurate reactive power sharing, even under parallel operation with line parameters mismatch, and reduced ${\bm{Q}}$ – ${\bm{P}}$ coupling. In addition, the proposed GFm-SST-PV system is equipped with a low-voltage ride-through controller to bypass faulty conditions safely. Furthermore, a linearized small-signal model of the whole system is developed, validated, and used to 1) investigate the system stability under broad variations of solar irradiance, power reserve, and control parameters and 2) provide guidelines for a coordinated design of all control parameters, considering all system dynamics and control loops interactions. Extensive time-domain simulations and hardware-in-the-loop real-time tests are conducted to verify all features and capabilities of the proposed configuration.