Effects of dynamic power electronic load models on power systems analysis using ZIP-E loads

TL;DR

This paper introduces ZIP-E load models incorporating dynamic power electronic components for more accurate power system analysis, revealing that traditional ZIP loads may overestimate instability and affect system stability assessments.

Contribution

The paper proposes a novel ZIP-E load model that combines static ZIP loads with dynamic power electronic loads for improved power system analysis.

Findings

ZIP loads destabilize networks faster than ZIP-E loads.

Transient oscillations are larger with ZIP loads.

Higher network loading increases sensitivity to load model choice.

Abstract

Power grids are seeing more devices connected at the load level in the form of power electronics: e.g., data centers, electric vehicle chargers, and battery storage facilities. Therefore it is necessary to perform power system analyses with load models that capture these loads' behavior, which has historically not been done. To this end, we propose ZIP-E loads, a composite load model that has a ZIP load with a dynamic power electronic, or E, load model. We perform small signal and transient analysis of the IEEE WSCC 9 Bus test case with ZIP and ZIP-E load models. For small signals, we conclude that ZIP loads destabalize networks significantly faster than corresponding ZIP-E loads. In stable cases, transient results showed significantly larger oscillations for ZIP loads. Further, we find that a higher network loading condition is correlated with a higher sensitivity to load model choice. These results suggests that the constant power portion of the ZIP load has a large destabilizing effect and can generally overestimate instability, and that attention should be drawn to load model choice if operating near a stability boundary.