Large-scale photovoltaic plant harmonic transmission model and analysis on resonance characteristics

Harmonics generated from large-scale grid-connected photovoltaic plant (GCPV) has the characteristics of high frequency and wide frequency range. So the adverse impact of distributed parameter of high-voltage cables becomes more significant. Based on an actual GCPV, harmonic output particularities were discussed according to its operating mechanism. Step-up transformer, reactive power compensation device, distributed capacitance of transmission line and the loads were considered, the passive multiport network model was established, and the transmission mechanism of harmonics in this network was analysed by the definition of resonance amplification factors. Double resonance curves of harmonic current were discovered, that is, the transmission line of different distance may amplify a harmonic current twice. The simulation and data measurement in the field were carried out based on a large-scale GCPV in Qinghai province. The proposed scheme was verified by the comparison of simulation data and measurements.