Steady-state model and power flow analysis of grid-connected photovoltaic power system

The power flow analysis of a power grid containing photovoltaic (PV) generating system is the foundation of studying steady-state characteristics of large- scale PV power station integrating into power grid. Generally, PV systems are coupled by power electronic converters. Thus, the steady-state modeling can be based on PV array characteristics and principles of power electronic transforms. The model in this paper can simulate steady-state operations of PV systems in condition of giving meteorological, PV system and power grid parameters. Moreover, the alternative and iterative method is used to obtain the unified solution of the model and power flow equations. Being compared with the actual PV station, analytical results indicate that the simulating error during noon time is very small and errors during morning and evening are relatively great. Also, variations of meteorological and power grid parameters will effect the system operation, but the irradiance is the greater one and the grid voltage variation has little effect. The power flow analysis is verified on IEEE 30-bus system, and PV power station can act as not only a PQ node, but a PV node which can supply reactive power to support voltage profiles.