Analysis Method of Fault Characteristics Considering Coupling Degree between Large-Scale Rectifier Load and Renewable Energy

As the scale of rectifier load and photovoltaic power generation is increasing, the impact on power system relay protection device becomes more. distinct. Some protection devices act more slowly than designed, and sometimes even act incorrectly. In order to study and reveal the causes of these anomalies, this paper presents electromagnetic transient models of large-scale rectifier load and photovoltaic power generation. Based on the practical power system network, a typical real-time simulation case is built for fault characteristics analysis in the tight coupling condition. Meanwhile, an index is raised for the coupling degree between rectifier load and photovoltaic power generation. A suggestion for testing power system relay protection based on this index, is present in the paper. At last, the fault characteristics with different coupling degree of large rectifier load and renewable energy are studied by real-time simulation. The result indicates that the harmonic of fault current is much more rich during AC fault with higher coupling degree. This phenomenon is more obvious in three-phase short-circuit fault.