Abstract: This paper presents Load Frequency Control (LFC) of a two-area thermal reheat power system considering
Governor Dead-Band (GDB) and Generation Rate Constraints (GRC) nonlinearities. A new Proportional-Double
Integral (PI2) controller is design and implemented in LFC loop. The proposed controller have two integrators can able
to reduce the area control error to zero even the system has complexities. The control parameters of the proposed
controller are optimized using Differential Evolution (DE) algorithm. The main merits PI2 controller is that it has good
stability during load variations, excellent transient and dynamic responses Moreover this paper deals with the concept of
LFC in two-area interconnected power system having coordinated control action with Redox Flow Battery (RFB) unit
places in area1 and Unified Power Flow Controller (UPFC) unit in series with the tie-line are capable of controlling the
network performance in a very fast manner and improve power transfer limits
Keywords: Differential Evolution algorithm, Proportional-Double Integral (PI2) controller, Redox Flow Battery and Thyristor
Controlled Phase Shifter.