Modal Energy for Power System Analysis: Definitions and Requirements

TL;DR

This paper clarifies the definitions and limitations of modal energy in power system analysis, highlighting its restricted applicability in inverter-dominated systems due to reliance on system normality.

Contribution

It provides a comprehensive clarification of modal energy definitions and their applicability, emphasizing the conditions under which these approaches are valid.

Findings

Modal energy mappings to eigenvalues hold only under system normality.

Mainstream modal energy approaches are not universally applicable.

Inverter-dominated systems challenge traditional modal energy analysis.

Abstract

Modal energy provides information complementary to and based on conventional eigenvalues and participation factors for power system modal analysis. However, modal energy definition is not unique. This letter clarifies the definitions and applicability of mainstream modal energy approaches, focusing on their mappings to eigenvalues and to the total system energy. It is shown that these mappings hold only under restrictive conditions, notably system normality, which limits their applicability in inverter-dominated power systems.