In this paper, a comparative study based

-This paper considers the impact of the Inductive Fault Current Limiter (IFCL) on d irect ional overcurrent relays coordination. The coordination problem is formulated as a non-linear constrained mono-objective optimization problem. The objective function of this optimizat ion problem is the minimizat ion of the operation time of the associated relays in the systems, and the decision variab les are: the time dial setting (TDS) and the pickup current setting (I P ) of each relay. To solve this co mplex non linear optimization problem, a variant of optimization algorith ms named Firefly A lgorith m (FA) is used. The proposed method is tested on 8-bus power transmission systems test systems considering the influences of current relay under three-phases short-circuit with and without IFCL for d ifferent locality. The results show the effectiveness of the solution.

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Abstract-This paper presents the application of the Modified Particle Swarm Optimizat ion (MPSO) technique for optimal settings zones for M HO distance relay protect 400 kV single transmission line of Eastern Algerian transmission networks at Algerian Co mpany of Electrical and Gas (Group Sonelgaz) co mpensated by series Flexib le A lternative current Transmission System (FACTS) i.e. Thyristor Controlled Series Capacitor (TCSC) connected at midpoint. The effects of TCSC insertion on the total impedance of a protected transmission line with respect to injected variab le reactance value (X TCSC ) in capacit ive and inductive boost mode depending of the firing angle (α) is considered. The modified setting zone protection for three zones (Z 1 , Z 2 and Z 3 ) is have been investigate in order to prevent circuit breaker nuisance tripping and improve the performances of distance relay protection. In this work our aim is to co mpare the performance of the proposed MPSO algorithm with an analytical method (AM). The findings demonstrate the outstanding performance of the proposed MPSO in terms of co mputation speed, rate of convergence, and feasibility. The simu lation results are co mpared with each other, and then the more perfect algorith m is considered.

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<div data-canvas-width="397.21009877040933">The demand for power electricity is growing fast and one of the main tasks for power engineers is to generate electricity from renewable energy sources (RES).</div><div data-canvas-width="277.2073926627698">Nevertheless, problems arise when the new generation is integrated in the power distribution network. Under this condition, the main purpose in this paper, an investigation of the effect of RES integration on the optimal coordination of directional over-current relays in distribution system, a dual simplex optimization algorithm has been presented to determine the coordination of directional over-current relays (DOCRs). The system used to check the efficiency of the optimization algorithm which is IEEE 33-bus models. The analysis is performed in MATLAB software environment.</div>

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Original scientific paperDue to the rising power demand and increasing population worldwide, electrical power networks have been extensively growing and striving to satisfy the escalating loads. This necessitates the need for using Flexible AC Transmission System (FACTS) devices which have become indispensable during normal and abnormal operating conditions. This paper investigates the impact of using series FACTS devices, namely Thyristor Controlled Series Capacitor (TCSC), GTO Controlled Series Capacitor (GCSC) and Thyristor Controlled Series Reactor (TCSR), on the impedance and power flow of a practical 400 kV transmission line in the Algerian power network. It also investigates the effect of varying the fault resistance on short-circuit calculations in the case of a phase to ground fault that occurs at the end of the compensated line. Analytical formulas of the employed FACTS devices, the system model under fault and short-circuit calculations are deduced and presented in the paper. Simulations results obtained using MATLAB are demonstrated for the compensated line and without compensation. These simulations are compared to show the effect of using these devices for the studied cases.It is concluded that GCSC provides better performance in the active and reactive power flow of the line under normal operating conditions and in reducing the fault current during abnormal operating conditions when the fault resistance increases. On the other hand, TCSR shows a better performance in maintaining higher voltages under fault with the increase of fault resistance.Key words: Thyristor Controlled Series Capacitor (TCSC), GTO Controlled Series Capacitor (GCSC), Thyristor Controlled Series Reactor (TCSR), Algerian power network, Phase to ground fault, Fault resistance, Short-circuit calculations.Usporedna analiza greške uzemljenja za praktični slučaj transmisijske linije s različitim FACTS uređajima. Zbog rastuće potražnje za električnom energijom i porasta svjetske populacije elektroenergetske mreže ubrzano rastu i podnose sve veće terete. Takav razvoj situacije doveo je do korištenja fleksibilnih AC transmisijskih sustava (FACTS) koji su postali nezamjenjivi tijekom normalnih i narušenih uvjeta na mreži. U ovom se radu istražuje utjecaj korištenja FACTS uređaja, tiristorski upravljani serijski kondenzatori, GTO upravljani serijski kondenzatori i tiristorski upravljana serijska reaktancija, na impedanciju i tok snage kod 400 kV transmisijske lijene u alžirskom elektroenergetskom sustavu. Istražuje se i utjecaj promjene otpora greške pri izračunu kratkog spoja u slučaju spoja faze na zemlju koje se događa na krajevima linije. Analitičke formule korištenog FACTS uređaja, model sustava s greškom i izračun kratkog spoja su izvedeni i prikazani u radu. Simulacijski rezultati dobiveni korištenjem MATLB-a prikazani su za linije sa i bez kompenzacije. Simulacije su uspoređene kako bi se prikazao učinak korištenja različitih uređaja. Zaključeno je da GTO upravljani serijski kondenzatori ima bolja svojstva kod toka radne i jalove...