Impact of Communication Delay on Frequency Regulation in Hybrid Power System Using Optimized H-Infinity Controller

ABSTRACT A communication infrastructure is essential for safe monitoring and control of isolated hybrid power system. For the hybrid system, integration of different renewable resources is required, such as wind turbine generator, diesel engine generator, aqua-electrolyser, and fuel cell along with storage unit. However, impacts of communication delay on dynamic performance on the hybrid power system, mainly load frequency control have not been reported by researchers. This paper presents the impact of communication delay profile in isolated hybrid distributed generation (DG) system for minimization of frequency deviation profile. The communication delays are one of the major problems and always present in a system during transmission of signal from remote terminal unit to control centre to individual unit. The frequency control problem is addressed for the hybrid DG system with communication delay. The delay is modelled by the second-order Padé approximation method. Particle swarm optimization (PSO)-tuned H-infinity loop shaping controller is used in this study for minimization of frequency deviation profile and compared with genetic algorithm (GA)-tuned H-infinity loop shaping controller and proportional integral-tuned H-infinity controller for different load conditions and change in system parameters. Performance of controllers is also validated with introducing nonlinearities in the system, such as generation rate constraints, time varying delay, and uncertainties. The results show that frequency deviation in presence of delay is found to be minimum for controller design by PSO-tuned H-infinity loop shaping of controller.