PV Grid Inverter Dynamics on Load Active and Reactive Power Demand for Weak Grid Stability

Energizing inductive loads on a weak grid network requires extra reactive power compensation such as STATCOM, capacitor bank, Grid-connected inverter system etc. The optimization of photovoltaic grid-connected power systems has limited the reactive power compensation to the inverter’s capacity and consideration of its life cycle. In balancing the two limitations, oversizing the inverter can enable reactive power injection with a long-living operation. However, allowing excessive reactive power flow can also affect the active power requirement of the inductive loads. In this paper, a three-phase Grid-connected PV inverter simulation is made to investigate the inverter’s and load’s behavior when injecting reactive power required by the load to maintain a sufficient voltage on the grid. The inverter was oversized to a 1.60 AC-DC ratio. The system is simulated on the day and night motor startup operation with a 5ph induction motor started on the direct online method. The simulation results show that the motor power absorption is deficient when high reactive power is compensated.