The future electric grid will consist of significant penetration of renewable and distributed generation that is likely to create a homogenous transmission and distribution (T&D) system, requiring tools that can model and robustly simulate the combined T&D networks. Existing tools use disparate models and formulations for simulation of transmission versus distribution grids and solving for the steady-state solution of the combined T&D networks often lacks convergence robustness and scalability to large systems. In this paper, we show that modeling both the T&D grid elements in terms of currents and voltages using an equivalent circuit framework enables simulation of combined positive sequence networks of the transmission grids with three-phase networks of the distribution grids without loss of generality. We further demonstrate that we can ensure robust convergence for these resulting large-scale complex T&D systems when the circuit simulation methods are applied to them. Our results illustrate robust convergence of combined T&D networks using a direct Newton-Raphson solver on a single machine for smaller sized systems and using a parallel Gauss-Seidel-Newton solver on multiple machines for larger sized systems with greater than million nodes.

中文翻译：

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组合输配电系统的稳态仿真

未来的电网将包括可再生和分布式发电的大量渗透，这很可能会创建同质的输配电（T＆D）系统，这需要能够对合并的T＆D网络进行建模和可靠模拟的工具。现有的工具使用不同的模型和公式来模拟输电与配电网，而解决组合式T＆D网络的稳态解决方案通常缺乏对大型系统的收敛鲁棒性和可扩展性。在本文中，我们表明，使用等效电路框架对T＆D网格元素进行电流和电压建模，可以模拟输电网格的正序网络与配电网格的三相网络的组合，而不会失去一般性。我们进一步证明，当将电路仿真方法应用到这些大型复杂T＆D系统时，我们可以确保这些系统的鲁棒收敛性。我们的结果表明，对于较小规模的系统，在单个机器上使用直接Newton-Raphson求解器，而对于具有超过一百万个节点的较大规模的系统，在多台机器上使用并行的Gauss-Seidel-Newton求解器，则组合的T＆D网络的鲁棒收敛。