Comparative Study of Dynamic Phasor and Harmonic State-Space Modeling for Small-Signal Stability Analysis

•Dynamic phasors and harmonic state-space are promising small-signal modeling methods.•Both methods provide linear time-invariant representations of time-periodic systems.•With same design choices, the models have same eigenvalues and transfer functions.•Due to truncation, models of time-periodic systems present spurious eigenvalues.•Spurious eigenvalues should be disregarded for eigenvalue-based stability assessment. This paper conducts a comparison of two promising frequency-lifted representations used in the state-space modeling of power-electronic converters: dynamic phasors and harmonic state-space. These methods originate from similar hypotheses and aim to tackle the time-periodicity problem observed in systems with multiple harmonic components in steady state. The paper derives the theoretical foundations of the methods with an emphasis on their similarities and differences, and applies them to a two-level voltage-source converter. The application demonstrates the effects of different truncation orders of the models infinite formulations. Stability analysis tools such as eigenvalues and transfer functions are examined and benchmarked against a classical dq-frame small-signal model.