**1. Introduction**

The integration of utilities being vertical, the task of separating the cost incurred in generation, transmission and distribution is quite di fficult. Thus, the utilities put an average tari ff on to their customer which relies on the aggregated fixed price for a specific period. Some of the external agencies fix the price which focuses more on consideration rather than economics. Occurrence of Congestion at a location in power transmission system will not be able to suit all the proposed bi/multilateral exchanges. It is due to the inability to incorporate the Existing Transmission Commitments (ETC), due to the infringement of operating constraints. A glimpse of a detailed survey related to managing the congestion issues occurring worldwide has been schemed in [1]. The authors have explained the techniques for consolidating deregulated market arrangements for the better utilizations of the power resources thereby providing solution to the issues [2]. A model with the inclusion of system stability criterion has been accounted for so as to relieve congestion [3]. A methodology for the embodiment of the reactive power services and real power loss while overseeing congestion has been considered [4]. The authors have examined the e ffects of FACTS arrangemen<sup>t</sup> for pacifying this problem [5]. The impact of congestion on the power system, and the financial signs of dispensing the associated cost venture have been discussed in [6]. The authors have proposed congestion managemen<sup>t</sup> based zones/cluster; wherein the zones are being decided by the congestion distribution factors [7,8]. A combination of pool and bilateral trading has been considered for managing the congestion in a market based environment [9]. The author has assessed a detailed review on managing the congestion in di fferent scenario of the market under privatization structure [10,11]. This paper ranks the managemen<sup>t</sup> of congestion activities and its trappings on socio-economic impacts has been addressed in a divergent private mob. An analytical model based optimal technology comprising elements such as transformer taps and optimal switching has been incorporated for eliminating congestion [12]. A secure path of managing congestion with the due consideration of stability has been urged in [13,14]. Here the optimization problem has been e ffectively handled incorporated with penalty constraints [15,16].

Managing the congestion can be eased with di fferent algorithm such as Simulated Annealing (SA), Random Search Method (RSM) and Particle Swarm Optimization (PSO) and tested on modified IEEE 30 bus system and IEEE 57 bus system. Further this issue has been dealt with the embodiment of nonconventional wind energy system [17]. This paper addresses the combined operation of energy utilization from hydro and wind is utilized for devising the mathematical model for bidding in a day-ahead energy market [18]. Adjusting the real power output of generators in order to meet the power demand is a real time challenge in the present scenario in the power grid. PHSU has commercially proven to meet the changes in power demand owing to its capability to start/stop quickly in accordance to change in load. The authors have presented the erection and devising of PHSU to serve peak demand. Further an insight analysis has been carried out on electricity pricing and its associated guidelines adopted [19]. This paper renders a wide vision into the recent development of PHSU in relation to its participation in deregulated energy market [20]. Further it addresses the flexibility of PHSU aiding in shift of generation thereby avoiding congestion and manages reliable supply of power in the grid. A formative structure has been incorporated with combined operation of hydro and PHSU for apprehending the volatility in pricing for in order to improvise the payo ff from the generators [21]. Implementation of PSHU along with thermal plants enabled a steady decrease in emission [22,23]. This paper interprets the saving in cost yielded by optimal use of PHSU when operated during peak demand and thermal usage during o ff-peak demand [24]. The superiority of PHSU elevated the e fficiency in energy transaction [25–27]. FPA and its variants have been developed in recent years which are found to yield better e fficient outputs in applications for optimization designing due to its single probability switching parameter [28]. It associates the non-linearity Levy flight mechanism which proves to be e ffectively suited for multi-objective for enhancing the algorithmic performance of exploring the distant pollinator thereby globally exploring and locally exploiting by the consistency of flowers chosen [29,30]. FPA has been tested on IEEE 30 bus system with three di fferent objective functions incorporating economic load dispatch and result obtained is compared with other optimization techniques proving for its robustness over other existing algorithms [31]. Symbiotic Organisms Search algorithm [32], Ant lion algorithm [33], Gravitational Search Algorithm [34], Teaching Learning Based Optimization (TLBO) [35] are few of the latest algorithms have been found proposed for extenuating congestion. Switching the transmission lines in optimal sequence is one of the novel technologies to subdue congestion [36]. A novel distribution Algorithm has been proposed using nash equilibrium for e ffective cost reduction due to wheeling [37]. The technological advancements employing Power Electronic circuitry for Hydro Energy Electric Systems contributes widely in terms of economical paymen<sup>t</sup> and space reduction [38]. The reliability of the PHSU is e ffectively eased with the incorporation of Doubly-Fed Induction Motor [39]. The future prospects of adventing compressed air storage embedded with PHSU has been discussed. This could increase the performance utilization of energy. This proves to be a viable solution for the power industry in the future [40].

The major contributions of the paper are as follows. The main idea is to propose a methodology for managing the problem of congestion with cost reduction by rescheduling the generators active power. To achieve this task, FPA Algorithm is presented here. The stimulus of the present e ffort is to benefit the ISO in reliving the congestion. Here, modified IEEE 30 bus system is used as the test case. Initially an outage is created to cause the Congestion which results in power flow violation in certain transmission lines and the Congestion cost has been computed. Then the novel FPA is schemed as an e fficient optimizing tool for rescheduling cost minimization as well as reduces the system losses. Further the rescheduling Congestion cost is compared with and without the application of FPA is computed. The e ffectiveness of the proposed Algorithm is proven in terms of minimized Congestion cost. To validate its e ffectiveness, the obtained results are compared with other optimization algorithms already reported in literature. Thereafter to replenish the varying load demand nature, a PHSU unit has been incorporated in it. The e fficacy of FPA algorithm incorporating with PHSU is then investigated in terms of congestion cost minimization.

The paper is methodized as follows: Section 2 deals with the frame work criterion of managing congestion by rescheduling of generator's active power with the inclusion of PHSU in terms of congestion cost and loss minimization. Section 3 accomplishesFPA as an e fficient optimizing tool for congestion cost minimization as well as reduces the system losses. Section 4 discusses the power flow violation due to congestion and the application of suitable methodology namely FPA. The e fficacy of FPA in benefitting the Independent System Operator (ISO) in reliving the congestion is presented here. Here, modified IEEE 30 bus system is used as the test case. There after it is validated with other optimization techniques. Section 5 presents the significance of PHSU incorporated in the test system in aiding further reduction in congestion cost, losses and voltage profile improvement embodying BSF and GSF. Furthermore an economic analysis of congestion cost reduction using FPA before and after the incorporation of PHSU is investigated.
