Robust Decentralized Secondary Control Scheme for Inverter-based Power Networks

TL;DR

This paper proposes a robust decentralized secondary control scheme for inverter-based microgrids that maintains stability and frequency regulation even under communication failures and synchronization errors.

Contribution

It introduces a unified decentralized control approach applicable to various inverter architectures, with theoretical stability guarantees and practical tuning criteria.

Findings

Successfully eliminates steady-state frequency deviation in simulations

Provides stability guarantees for decentralized control under errors

Achieves good frequency regulation and fair power sharing

Abstract

Inverter-dominated microgrids are quickly becoming a key building block of future power systems. They rely on centralized controllers that can provide reliability and resiliency in extreme events. Nonetheless, communication failures due to cyber-physical attacks or natural disasters can make autonomous operation of islanded microgrids challenging. This paper examines a unified decentralized secondary control scheme that is robust to inverter clock synchronization errors and can be seamlessly applied to grid-following or grid-forming control architectures. The proposed scheme overcomes the well-known stability problem that arises from parallel operation of local integral controllers. Theoretical guarantees for stability are provided along with criteria to appropriately tune the secondary control gains to achieve good frequency regulation performance while ensuring fair power sharing. The efficacy of our approach in eliminating the steady-state frequency deviation is demonstrated through simulations on a 5-bus microgrid with four grid-forming inverters.