Hybrid PV Power Plant Control Strategies for Black-start Capability and Grid Support Enhancement

Abstract

This thesis explores the potential of a large-scale hybrid Photovoltaic-Battery Energy Storage System (PV-BESS) to deliver black start ancillary services, essential for power system restoration following partial or complete blackouts. A novel black start strategy is introduced, leveraging both grid-forming and grid-following converters, unlike conventional strategies which predominantly use grid-forming converters. The study's findings highlight the robustness of the proposed control strategy in addressing key challenges such as transformer inrush current during energization, maintaining frequency stability during load pickup, and achieving seamless synchronization with the grid. For transformer energization, the proposed method, integrated within the grid-forming control loop, successfully mitigates inrush current without external devices, outperforming traditional techniques. In load pickup scenarios, the battery, augmented by PV power, effectively managed substantial loads. by secondary frequency regulation that shifted the load from the battery to the PV, restoring nominal frequency. To ensure consistent power generation from the PV, a modified Perturb and Observe (P&O) algorithm was employed. The synchronization process with the grid was achieved by strategic switching within control loops, particularly the outer ones. Overall, the proposed black start strategy demonstrates significant advancements in the control and operation of large-scale hybrid PV-BESS, ensuring efficient and reliable power system restoration.

Date of Award	2 Jul 2024
Original language	American English
Supervisor	Mohamed El Moursi (Supervisor)