Abstract
This paper discusses a proposed frequency restoration
controller which operates as an outer loop to frequency
droop for voltage-source inverters. By quasi-equilibrium
analysis, we show that the proposed controller is able to provide
arbitrarily small steady-state frequency error while maintaing
power sharing between inverters without need for communication
or centralized control. We derive rate of convergence, discuss
design considerations (including a fundamental trade-off that
must be made in design), present a design procedure to meet
a maximum frequency error requirement, and show simulation
results verifying our analysis and design method. The proposed
controller will allow flexible plug-and-play inverter-based networks
to meet a specified maximum frequency error requirement.