Application of Combined Transmission-Distribution System Modeling to WECC Composite Load Model

The WECC Composite Load Model (CLM) is one of the most comprehensive load models used in transmission system dynamic studies. It is expressed by numerous parameters representing an aggregated load. The default parameter values of the CLM cannot always properly represent the distribution system. In this paper, a systematic method for determining the values for the parameters affected by the load composition and configuration of a distribution system is described with the aid of the Combined Transmission-Distribution System (CoTDS) modeling method. Since the CoTDS model considers the detailed behavior of the loads in the distribution system, it serves as a guiding tool to tune the CLM parameters. Simulation of several test cases are performed using a WECC 9-bus transmission system with a 160-node distribution system feeder. The results demonstrate the effectiveness of the proposed method to properly represent the distribution system in the CLM.