Temperature Droop-Based Dynamic Reactive Power Sharing Technique to Improve the Lifetime of Power Electronic Converter

Abstract

Thermal stress because of mean junction temperature (<inline-formula><tex-math notation="LaTeX">$T_{{{jm}}}$</tex-math></inline-formula>) and junction temperature swing (<inline-formula><tex-math notation="LaTeX">$\Delta T_{{j}}$</tex-math></inline-formula>) reduces the lifetime of the power electronic (PE) converters. It is beneficial to distribute the stress evenly among the converters operating in parallel in a system like microgrid to improve their lifetime. The existing techniques usually only distribute stress due to <inline-formula><tex-math notation="LaTeX">$T_{{{jm}}}$</tex-math></inline-formula>. A few techniques are based on the accumulated damage in PE converters do not necessarily mitigate the effect of <inline-formula><tex-math notation="LaTeX">$\Delta T_{{j}}$</tex-math></inline-formula>. Moreover, most of the the existing techniques are not applicable for nondispatchable energy source like PV. The intermittent nature of active power generation profile of the PV inverter further reduces the lifetime of the PE converters operating in an islanded microgrid. To address this issue, a temperature droop-based dynamic reactive power sharing (TDDRPS) technique is proposed for an islanded ac microgrid to distribute the thermal stress due to both <inline-formula><tex-math notation="LaTeX">$T_{{{jm}}}$</tex-math></inline-formula> and <inline-formula><tex-math notation="LaTeX">$\Delta T_{{j}}$</tex-math></inline-formula>. The stability of the proposed TDDRPS technique is mathematically analyzed. Finally, the proposed technique is validated through simulation and experimentation on a scaled down laboratory prototype of microgrid.