A Decentralized Reliability-Enhanced Power Sharing Strategy for PV-Based Microgrids

Microgrid (MG) technologies facilitate reliable, efficient, and economic operation of distributed resources such as photovoltaic and battery storage systems. The well-known droop method controls different sources in an MG to properly share power supply. However, utilizing the droop method poses two major challenges. First, while the droop method can prevent converter overloading, it cannot protect them from overstressing, thus deteriorating system reliability. Second, operating a 100% renewable-based MG requires a supervisory unit to monitor and control energy flow for load-generation balance. However, the supervisory unit relies on communication systems which impacts overall system reliability by being exposed to single-point failures and cyberattacks. This article proposes a decentralized power sharing approach that restricts thermal damage of converter components to avoid over-stressing converters. The main goal is to improve overall system performance and reliability by appropriately sharing active and reactive power among different sources without using communication systems. The simulations and numerical analysis show that the proposed decentralized strategy will properly control the power and energy flow among different sources. Moreover, it prevents over-stressing converters, consequently enhancing the overall reliability of the MG. An experiment is also presented to demonstrate the effectiveness of the proposed decentralized control approach.