Novel control scheme for high power centralized PV-grid system to realize functionalities of AVR and governor as in conventional generators

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Abstract
This paper proposes a novel control technique for a large centralized PV-grid generating station to incorporate the attributes of AVR and governor and to make it perform like conventional steam and hydro turbine generators. The objective is to be able to interface and integrate large PV generators with the power grid in a “seamless” manner. The PV power capacity is considered comparable to any of the existing, large generator capacity with a typical load cycle. The proposed control strategy allows precise active power control with the set dynamics of frequency droop characteristic akin to the action of governor in conventional generators, to share the load and to control the bus frequency under certain conditions. The control also has the feature of sharing maximum capacity under normal operation working with MPPT scheme. The proposed control strategy also realizes the AVR action of conventional generators, so as to regulate the bus terminal voltage by reactive power control. Complete system modeling and analytical approach is presented to design the compensator and tune the PI regulators of the current control loops. Simulation results are presented for the system under study, showing the efficacy of the proposed control strategy. The system is designed in hardware to validate certain aspects of the simulation results.