Uniformity of the Harmonic Stability and the Frequency/Voltage Stability of the Converter-Integrated Power System

The large-scale integration of the renewable sources and power electronic equipment diminishes the system inertia and damping apparently and triggers the incidents related to the system harmonic stability and the frequency/voltage stability worldwide. Previously, the system harmonic stability and the frequency/voltage stability are usually regarded as two independent subjects and studied separately. Their inner relationship lacks in-depth investigation and remains unclear. To address this issue, this manuscript first reviews the dq admittance based harmonic stability analysis model and the PQ/?V transfer function based frequency/voltage stability analysis model. On this basis, by proper matrix transformation, this manuscript demonstrates the uniformity of the harmonic stability and the small-signal frequency/voltage stability. The results reveal that in a certain synchronous reference frame, the d-axis harmonic stability corresponds to the frequency stability while the q-axis harmonic stability relates to the voltage stability. In other words, the system harmonic stability and the frequency/voltage stability can be described by an unified model and analyzed simultaneously. Finally, the correctness of the proposed analysis is verified by the frequency and time domain simulations.