High-voltage direct current (HVDC) systems are increasingly incorporated into today's AC power grids, necessitating optimal power flow (OPF) tools for the analysis, planning, and operation of such hybrid systems. To this end, we introduce hynet, a Python-based open-source OPF framework for hybrid AC/DC grids with point-to-point and radial multi-terminal HVDC systems. hynet's design promotes ease of use and extensibility, which is supported by the particular mathematical model and software design presented in this paper. The system model features a unified representation of AC and DC subgrids as well as a concise and flexible converter model, which enable the compact description of a hybrid AC/DC power system and its OPF problem. To support convex relaxation based OPF solution techniques, a state space relaxation is introduced to obtain a unified OPF formulation that is analogous to the OPF of AC power systems. This enables the direct generalization of relaxation-related results for AC grids to hybrid AC/DC grids, which is shown for the semidefinite and second-order cone relaxation as well as associated results on exactness and locational marginal prices. Finally, hynet's object-oriented software design is discussed, which provides extensibility via inheritance and standard design patterns, and its robust and competitive performance is illustrated with case studies.

中文翻译：

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$hynet:$ 混合交流/直流电源系统的最佳潮流框架

高压直流 (HVDC) 系统越来越多地并入当今的交流电网，因此需要优化潮流 (OPF) 工具来分析、规划和运行此类混合系统。为此，我们介绍了 hynet，这是一种基于 Python 的开源 OPF 框架，用于具有点对点和径向多端 HVDC 系统的混合 AC/DC 电网。hynet 的设计提高了易用性和可扩展性，这得到了本文提出的特定数学模型和软件设计的支持。该系统模型具有交直流子电网的统一表示以及简洁灵活的变流器模型，可以对混合交流/直流电力系统及其OPF问题进行紧凑描述。为了支持基于凸松弛的 OPF 解决方案技术，引入状态空间松弛以获得类似于交流电源系统的 OPF 的统一 OPF 公式​​。这使得 AC 电网的松弛相关结果直接推广到混合 AC/DC 电网，这显示为半定和二阶锥松弛以及有关准确性和位置边际价格的相关结果。最后，讨论了 hynet 的面向对象软件设计，它通过继承和标准设计模式提供了可扩展性，并通过案例研究说明了其稳健和有竞争力的性能。这显示了半定和二阶锥松弛以及有关准确性和位置边际价格的相关结果。最后，讨论了 hynet 的面向对象软件设计，它通过继承和标准设计模式提供可扩展性，并通过案例研究说明了其稳健和有竞争力的性能。这显示了半定和二阶锥松弛以及有关准确性和位置边际价格的相关结果。最后，讨论了 hynet 的面向对象软件设计，它通过继承和标准设计模式提供可扩展性，并通过案例研究说明了其稳健和有竞争力的性能。