An Analysis of the Sensitivity of WECC Grid Planning Models to Assumptions Regarding the Composition of Loads

MEPPI performed “An Analysis of the Sensitivity of WECC Grid Planning Models to Assumptions Regarding the Composition of Loads” project in collaboration with the University of California Lawrence Berkeley National Laboratory (LBNL), the Western Electricity Coordination Council (WECC), and associated WECC members. The overall objective of this project is to conduct a parametric set of simulations that explore the sensitivity of WECC’s planning models to uncertainties in the composition and behavior of loads. The results of the simulations performed in this study are expected to provide guidance that transmission planners can follow in refining the composition of loads used to conduct future planning studies.

The composite load model under study was developed, tested, and implemented in major software packages utilized by WECC (PSS/E, PSLF, and PowerWorld). The load data is currently built for 24 hours, four seasons, and various types of substations by a data management tool. The load model under study has been incorporated and is in use today in the Phase I portion of the model development. Phase 1 of the load model development includes all parameters for the step-down transformer, distribution equivalent, four types of motors, electric load such as fluorescent lighting, and static load. Phase 1 of the load model development ignores the stalling impact of air-conditioning motor loads, and therefore, is disabled by setting the Tstall parameter to a high value (e.g. 9999). MEPPI performed this study with the motor stalling impact for air-conditioner motor loads enabled by setting a realistic value for Tstall (referred to as Phase 2 of the load model development).

This analysis focused on the sensitivity of the composite load model to a variation of parameters that will impact the recovery of the system. Refer to Table ES-1 for the most influential parameters observed for Motor A, Motor B, and Motor C. Refer to Table ES-2 for the most influential parameters observed for Motor D.