Comparison of Coupling Techniques on Transmission and Distribution Co-Simulation with Distributed Generation and Load Growth

Abstract

The increased demand for electrical power causes challenges with new power system planning and operations. These challenges are deepened with the simultaneous integration of Distributed Energy Resources (DERs) and Load Growth (LG) in distribution networks. However, realistic and practical modelling and simulation of DER’s interactions under load growth with the Transmission and Distribution (T&D) networks is critical to assess the effects and advantages of DERs. This study thus, compared the different coupling techniques on transmissions and distribution co-simulation with Distributed Generation (DG) at varying loads. The T&D co-simulation test network comprises the Western System Coordinating Council (WSCC) 9-bus transmission network and the IEEE 16 nodes as the distribution network. Three coupling techniques; Decoupled (DC), Loosely Coupled (LC), and Tightly Coupled (TC), are simulated in MATPOWER environment, under DG penetration and load growth. The results show that the DC model is considerably less precise when compared to the LC model. The average percentage error in boundary variables was consistently 20 to 40 times worse in the DC model compared to the similar LC and TC models. Additionally, in both DC and LC models, the size of the percentage error in the power demand variable is greater than the magnitude of the voltage at the T&D Point of Common Coupling (PCC). This study provides valuable information on developing robust co-simulation frameworks essential for modern power grids, supporting sustainable energy transitions and enhancing grid resilience.