Competitiveness of PV Inverter as a Reactive Power Compensator considering Inverter Lifetime Reduction

Abstract

With the increasing adoption of photovoltaic systems (PVs) in distribution grid, many researchers and grid operators have proposed and started to utilise PV inverters for local reactive power compensation (RPC). The local RPC has been shown to reduce losses in the system, and to help maintain voltage within acceptable range. Moreover, RPC using PV is already competitive when compared with traditional reactive power devices. Nevertheless, the RPC using a PV inverter increases the current flowing through it, and hence the losses and the temperature of its components. As a result, the lifetime of the inverter will be reduced with increasing reactive power usage, incurring costs to the system owner and increases the PV levelised cost of electricity (LCOE). It is therefore imperative to consider the inverter degradation, as a rise in the LCOE may cause PV to be less competitive compared to other energy sources. Thus, in this work, the competitiveness of PV inverter as a reactive power compensator is reassessed, accounting for the inverter lifetime reduction. Case studies on test systems based on real distribution network are conducted to illustrate the importance of considering inverter lifetime reduction. The results from this work can be used by PV owners, power system operators and regulators in determining whether to utilise PV for RPC, and to what extent, based on their market situation.