Enhanced power flow control of distributed generator units by using virtual impedance scheme

The growing of environment restrictions has driven the insertion of renewable energy sources (RES) in low-voltage networks. However, the undispatched nature of these units could produce power quality issues like voltage fluctuations, harmonic distortion or frequency deviation. It could be worse if a weak grid connects these RES units. This paper proposes a virtual impedance scheme for achieving the suitable coupling between the active and reactive power flows in the low-voltage distribution grids. It can be designed independently of the standard RES control system. The current control loop employs the indirect control approach. With the proposed method, the power flow control can be implemented employing programmable impedances scheme. Experimental results validated the proposed impedance shaping strategy.