scholarly journals Suggestion of a New Protection Scheme for a Transmission System Equipped with a Thyristor-Controlled Series Capacitor

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2250
Author(s):  
Minh-Chau Dinh ◽  
Minh-Quan Tran ◽  
Jae-In Lee ◽  
Seok-Ju Lee ◽  
Chur Hee Lee ◽  
...  
Keyword(s):  
Transmission Line ◽  
Power Flow ◽  
Operation Mode ◽  
System Stability ◽  
Test Bed ◽  
Distance Relay ◽  
Protection Scheme ◽  
Thyristor Controlled Series Capacitor ◽  
Real Time Digital Simulator ◽  
Series Capacitor

A thyristor-controlled series capacitor (TCSC) is employed to a transmission line in order to enhance the usable capacity of the present as well as upgraded lines, improve system stability, reduce losses, and improve power flow control capability. However, in an abnormal situation, the TCSC may transit from the existing operation mode to the other mode according to its control system and protection strategy. There is much difference in the impedance of the TCSC between each mode. This threatens the reliability of the conventional protection system, especially the distance relay, that works based on the measurement of line impedance. In this paper, we suggest a new protection scheme for a distance relay of a transmission line equipped with a TCSC. In the suggested method, in order to mitigate the effect of the TCSC in the fault loop, the TCSC injected voltage is subtracted from the measured phase voltage before supplying the voltage signal to the distance relay. The suggested scheme was verified by a real time digital simulator (RTDS)-based closed-loop test bed of a protective relay. The effect of the TCSC in the fault loop was completely mitigated. The distance relay works properly with the suggested scheme.

scholarly journals Real and Reactive Power Control by using 48-pulse Series Connected Three-level NPC Converter for UPFC

2011 ◽  
pp. 1-5
Author(s):  
A. Naveena ◽  
M.Venkateswara Rao
Keyword(s):  
Transmission Line ◽  
Power Flow ◽  
Reactive Power ◽  
System Stability ◽  
Unified Power Flow Controller ◽  
Control Mechanisms ◽  
Active And Reactive Power ◽  
Reactive Power Flow ◽  
Flow Controller ◽  
Power Flow Controller

The equipments based on the power electronics have been improved under the name of Flexible Alternating Current Transmission Systems (FACTS) in the last years. Unified Power Flow Controller (UPFC) is the most widely used FACTS device to control the power flow and to optimize the system stability in the transmission line. UPFC is a FACTS devices that can control active and reactive power flow in transmission line by means of injection controllable series voltage to the transmission line. This paper proposes a new connection for a Unified Power Flow Controller (UPFC) to control the active and reactive power flow control in two sides of a transmission line independently and it regulates bus voltage in the same transmission line, furthermore it is possible to balance line current too. This connection of the UPFC will be called an center node UPFC (C_UPFC). It is one of the newest devices within the FACTS technology. The structure and capability of the C_UPFC is discussed and its control scheme is based on the d-q orthogonal coordinates. According to this, the performance of UPFC for several modes of operations using different control mechanisms based on Proportional-Integral (PI) and PID based controllers has been studied. The obtained simulation results from Matlab/simulink confirm the effective features.

scholarly journals Effective Utilization of Transmission Line Capacity in a Meshed Network with Series Capacitor Upto its Thermal Limit

2020 ◽  
Vol 8 (6S) ◽  
pp. 9-13
Keyword(s):  
Power Systems ◽  
Power System ◽  
Transmission Line ◽  
Power Flow ◽  
Power Transmission ◽  
Power Delivery ◽  
Thermal Limit ◽  
Effective Utilization ◽  
Generation Cost ◽  
Series Capacitor

Power system networks are becoming interconnected for the purpose of power delivery to decrease the overall power generation cost. With insufficient control, the power systems become more complicated to function and less secure. The economics of AC power transmission have always forced the planning engineers to transmit as much power as possible through a given transmission line. The smaller and thermally limited lines are crowded in many networks while other higher capacity lines run well below their thermal maximum. When series capacitors are introduced in the higher voltage cables, power may be transferred from the overloaded lines, maximizing the use of the existing line as well as complementing the performance of the power system. In this paper, a three-line meshed power system network with different thermal line limits is considered for the purpose of showing effective utilization of line network for maximum power flow through the intended line with series capacitor compensation. The simulations are performed by using PowerWorld simulator confirms the addition of series capacitor increases the power transfer through the line up to its thermal limit

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