Co-Simulation of Transmission and Distribution Systems - From Modeling to Software Development.

As the penetration of Distributed Energy Resources (DERs) increases, it becomes critical to model these resources adequately in bulk power system (BPS) operation and planning studies. Adequate in this context refers to capturing the characteristics of the distribution system to the required degree such that reasonable estimates about BPS stability can be ascertained. Historically, performing such studies on a large transmission system connected to multiple distribution systems have been limited due to the unavailability of software capable of executing high fidelity simulation at the required scale on personal workstations i.e. not having to resort to high performance computing resources. In this paper, we present TDcoSim, an open source software that allows user to perform large scale high fidelity simulation for BPS planning and operation studies and (a) outline the necessary details required to build such software, (b) present the practical challenges faced during the development of TDcoSim.