Modified droop control for low voltage single phase isolated microgrids

This paper develops a control strategy for converters in low voltage single phase isolated microgrids. Droop control technique for low voltage is used to control the active power as function of the voltage amplitude, and reactive power as function of frequency deviation. This control suppresses the use of physical communication between the power converters by simply utilizing local measurements, allowing its connection to the system without adjustment. Some concepts as microgrids and types of inverters connected, such as grid-forming, providing and supporting inverters are introduced. The individualized droop control for low-voltage systems is demonstrated, where it is more convenient to use active power as function of the magnitude of the voltage. A novel modified droop control equation is proposed to compensate the voltage drop at line resistance. The line impedance influence in power-sharing is also reduced. The validity of this new approach is proven by simulations that compare both droop control types and presents the effective improvement in active power-sharing and voltage regulation at microgrids common bus. A reduction of the power-sharing difference from 1041W to 341W is achieved with the new equation, and a voltage regulation from 204V to 210V. The reactive power-sharing is also verified.