Grid-Forming Inverter Control for Power Sharing in Microgrids Based on P/f and Q/V Droop Characteristics

Grid-forming inverters are anticipated to be integrated more into future smart microgrids commencing the function of traditional power generators. The grid-forming inverter can generate a reference frequency and voltage itself without assistance from the main grid. This paper comprehensively investigates grid-forming inverter modelling and control methodology. A decentralized method employing an active power versus frequency P - f droop and a reactive power versus voltage Q - V droop is exploited to drive the operation of the grid-forming inverter. This decentralized method ensures balancing the supply and demand beside the power-sharing task between two or more inverters. The performance of the grid-forming inverter is examined by monitoring the frequency and RMS voltage of the inverter bus for three different periods of a varying PQ load. In addition, the performance of the resultant droop is compared with the assumed droop to validate the effectiveness of the proposed method. Finally, two grid-forming inverters equipped with the same droop characteristics are connected to a single load to observe the power-sharing concept among them. All simulations are implemented and executed using Matlab/Simulink version R2014b.

Automated summary

This paper investigates the modeling and control methodology of grid-forming inverters, using a decentralized control strategy to drive the operation of the inverters for supply-demand balancing and power-sharing among multiple inverters. The effectiveness of the proposed method is validated by monitoring the frequency and voltage of the inverters under varying PQ loads and comparing the performance with the assumed droop characteristics. The concept of power-sharing among two grid-forming inverters connected to a single load is also observed.