Load Monitoring: CEC/LMTF Load Research Program

This report is intended to serve as a reference for future load monitoring projects. The identification of specific vendor's equipment/software, etc. in this document is for research documentation only and does not constitute an endorsement of these items. Load monitoring provides an important means to understand load behavior in the actual system. This understanding helps to develop load models to represent the load behavior in simulation studies. Load monitoring provides measured data needed for load model validation, load composition studies, and load uncertainty analysis.

Depending on various needs, load monitoring may be implemented differently with different monitoring hardware, different measured quantities, and different requirements for sampling rates, signal types, record length and availability, with different costs. Potential load monitoring options include traditional
supervisory control and data acquisition (SCADA), phasor measurement units (PMUs), portable power system monitors (PPSMs), digital fault recorders (DFRs), protective relays, power quality monitors, and a low-cost monitoring device being developed by Western Electricity Coordinating Council (WECC) Disturbance Monitoring Working Group (DMWG). Characteristics of these options are summarized in this report.

Current load monitoring practices at several utility companies are presented as examples of load monitoring. Each example consists of the following aspects of load monitoring: objective of load monitoring, monitoring location selection, description of monitoring equipment, communication for load monitoring, cost, and use of the data. The purpose of load monitoring is to provide better load characterization and better load management, i.e., the core element of load monitoring is focused on applications. Five load monitoring applications are proposed in this report, with some preliminary case studies:

• Load monitoring for top-down load composition: The total load profile obtained from load monitoring data can be decomposed to derive fractions of individual load types if load profiles of individual load types are known.
• Load monitoring for load composition validation: Load profiles generated by the load composition model can be validated against load profiles derived from load monitoring data.
• Load monitoring for load model validation: The general approach of model validation is to compare model simulation against measurements, as was applied to WECC generator model validation. Load monitoring provides the basis for load model validation.
• Load monitoring for uncertainty analysis: Statistical analysis can be performed on load monitoring data to quantify load variations over selected time periods.
• Load monitoring for load control performance evaluation: This is the trend that loads will play a more and more active role in managing the power system. Similar to generator performance monitoring, load monitoring can be used to ensure the load behaves as designed for correct credits and control enforcement.