In a large-scale offshore wind-to-hydrogen system, input-series converters are utilized to step down medium-voltage DC (MVDC) to low-voltage DC (LVDC) for supplying alkaline electrolyzers. These electrolyzers require a minimum power threshold to remain operational; falling below this threshold causes some units to shut down, leading to voltage imbalances across the series-connected converter modules. This imbalance introduces overvoltage risks and limits system functionality during periods of low wind generation, making conventional converter configurations unsuitable for low-load conditions. To address this challenge, this paper proposes a modified input-series output-parallel (ISOP) architecture that ensures continuous and stable operation across a wide range of power levels. A dedicated power-balancing circuit is introduced to manage unequal power distribution, with a detailed analysis of its hardware implications. Additionally, a coordinated system-level control strategy is developed to ensure reliable power delivery and minimize transient stress under all operating scenarios.

Continuously expanding deployments of distributed power-generation systems (DPGSs) are transforming the conventional centralized power grid into a mixed distributed electrical network. The modern power grid requires flexible energy utilization but presents challenges in the case of a high penetration degree of renewable energy, among which wind and solar photovoltaics are typical sources. The integration level of the DPGS into the grid plays a critical role in developing sustainable and resilient power systems, especially with highly intermittent renewable energy resources. To address the challenging issues and, more importantly, to leverage the energy generation, stringent demands from both utility operators and consumers have been imposed on the DPGS. Furthermore, as the core of energy conversion, numerous power electronic converters employing advanced control techniques have been developed for the DPGS to consolidate the integration. In light of the above, this paper reviews the power-conversion and control technologies used for DPGSs. The impacts of the DPGS on the distributed grid are also examined, and more importantly, strategies for enhancing the connection and protection of the DPGS are discussed.