The influence of pv inverter reactive power injection on grid voltage regulation

Despite their increasing levels of penetration into electrical grid distribution systems, PV based distributed generation (DG) systems are still not yet well regarded as a useful contributor to grid voltage regulatory support. However, there is increasing recognition of the potential for these inverter based systems to not only inject real power into the grid, but also to inject/absorb reactive power to/from grid to help manage the voltage profile of a distribution feeder. Various reactive power management strategies have been recently proposed to address this issue, using alternative voltage-reactive power relationships. However, little comparative evaluation of these strategies has been presented to date. This paper addresses this issue by exploring the voltage regulation response of a number of alternative reactive power strategies when applied to a multi-bus grid feeder, with a PV DG system connected to each feeder bus. The investigation takes into account a variety of system characteristics such as feeder impedance, dynamic transformer tap changing, different load types and levels of PV penetration. A detailed power system model has been developed using the DIgSILENT power network simulation package, and results are presented using this simulation to illustrate the capability of PV DG units to assist with voltage regulation of LV feeders.