ارائه روش تفاضل عرضي تواني جهت بهبود حفاظت خطوط انتقال دو مداره و عدم اشباع ترانسفورماتورهاي جريان

Presenting a Power Differential Transverse Method to Improve the Protection of Double-Circuit Transmission Lines an‎d the De-saturation of Current Transformers

مهندسي برق

The power transmission system is one of the most important components of a power system, an‎d its correct an‎d acceptable protection is very important. Double-circuit transmission lines have been widely used in modern power systems in order to increase the reliability an‎d security for the transmission of a large part of the electrical energy an‎d due to the environmental an‎d economic advantages they have over single-circuit lines. As the transmission system becomes more complex, the parameters of the system naturally change an‎d the way it is protected must change in order to protect the transmission system more accurately. In this study, a new way of protecting double-circuit lines based on the power differential method is presented. The basis of current differential protection is used to protect transformers, motors, generators, buses an‎d other types of power equipment by measuring the input an‎d output current. The differential relay also detects the occurrence of a fault in the equipment if there is a difference in the differential quantity on the two sides of the equipment. In longitudinal differential protection, due to the distance between the two sides of the equipment, appropriate communication channels must be used for data transmission. The purpose of this study is to present a power transverse difference method to improve the protection of double-circuit transmission lines an‎d prevent current transformers from being saturated. This method is one of the power transverse difference protection methods an‎d does not require equipment an‎d communication channels between the relays on both sides of the transmission line for operation an‎d is faster an‎d more reliable than current schemes. In this scheme, the complex power value for each of the two circuits in each bus is calculated using the voltage an‎d current signals measured on both sides of the transmission line. Then, by calculating the incremental complex power, the new gamma quantity an‎d the new gamma complex plane are defined. The gamma plane is considered a modified form of the alpha complex plane. The alpha plane is drawn from the ratio of the current phasors on both sides of the line. The phase under fault is identified by the gamma plane, while the gamma plane is drawn using complex power. To determine the circuit under fault, the amplitudes of the incremental complex powers in the two circuits are compared. Based on this comparison, the faulty circuit is identified. The proposed method is simulated on a sample power system in PSCAD/EMTDC software an‎d its output is transferred to Matlab software for algorithm execution. The results of the present study show that the proposed method detects internal an‎d external faults of a two-circuit transmission line well in all conditions an‎d shows proper performance.

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