Decentralized power control management with series transformerless H-bridge inverter in low-voltage smart microgrid based P/V droop control

This paper presents the power flow control between the main grid and the microgrid in 400 V low-voltage distribution network using series transformerless H-bridge inverter. This series converter is attached directly in series with the line, connecting the main grid and the microgrid with each other. It controls the real power flow depending on the state of both networks and by injecting series voltage that changes the microgrid side voltage. Therefore, the microgrid units will respond directly to the changes of the series converter set points and vice versa. Controlling the power flow in the line using the series converter is investigated by implementing two novel control strategies. The feasibility of the control strategies is validated during both capacitive and inductive operation modes. FFT analysis of the PCC voltage has been investigated to determine the THD caused by the series converter during both modes of operation. Also, system performance with and without P/V droop control and real power flow limit at PCC are also verified during both modes of operation. Several simulation cases have been demonstrated to investigate the feasibility of the series converter concept. SimPowerSystems and PLECS tool boxes of Matlab/Simulink software are utilized to implement the proposed work.