A Stability Quantitative Analysis Method of Three-Phase Four-Wire Grid-Connected Systems Considering Frequency Coupling and Sequence Components Coupling

Abstract

Distribution three-phase four wire power systems are undergoing significant evolutions in physical and technical features as a result of the large-scale integration of rooftop solar photovoltaics. For such multi-converter power systems, the occurred oscillation issues usually involve a variety of components. In addition, the intertwined relationship between dual frequency coupling effect and sequence components coupling effect complicates the analysis processes and makes the existing analysis results not suitable. To analyze the oscillation characteristics accurately of such system, this paper proposes a quantitative analysis method of oscillation mode based on the admittance network model, which considers dual frequency coupling effect, sequence components coupling effect and their intertwined relationship. In addition, a method to calculate the accurate characteristic roots effectively and flexibly based on a partitioned interval ant colony algorithm is also proposed. Finally, the node oscillation participation factor and oscillation mode sensitivity are defined to reveal the oscillation characteristics and laws of the three-phase four-wire grid-connected systems. The time-domain simulations results implemented in MATLAB/Simulink validate the analytical results.

Keywords

• Three-phase four wire system
• dual frequency coupling effect
• impedance
• quantitative analysis
• oscillation mode