Optimization Application in Integrated Transmission and Distribution Operation: Co-Simulation Approach

The load increment as the consequence of electrification of everything in the modern distribution networks, makes it imperative to analyze the interactions between electric power transmission and distribution (T&D) systems. Such a massive electrification may deteriorate voltage profiles and power exchanges, which results consequently in lower grid efficiency. As a low-cost and effective solution, the installed controllable devices for voltage in distribution networks such as under-load tap changer (ULTC) and capacitor banks can be optimized to overcome the aforementioned challenges. This paper proposes a new integrated transmission and distribution co-simulation platform where the aggregated loads in transmission system simulator (i.e. MATLAB) are replaced by a distribution network modeled in distribution system simulator (OpenDSS) through a Python interface. The overall T&D system efficiency is then optimized while maximizing loading margin (LM) and minimizing the total system power losses are contemplated as two objective functions. The proposed approach is applied on a constructed T&D grid with 68K nodes and the results demonstrate that the efficiency of the T&D grid can be improved by optimal setting of the control variables.