State‐of‐the‐art on the protection of FACTS compensated high‐voltage transmission lines: a review

Abstract

In recent years, the inclusion of flexible AC transmission systems (FACTS)-based compensating devices such as a thyristor-controlled series capacitor (TCSC) and a unified power flow controller (UPFC) has been increased in high-voltage power transmission systems due to numerous technical and economical benefits. However, the operation of such FACTS devices introduces harmonics and non-linearity in power system and causes fast changes in line impedance. As a result, the most widely used fixed impedance setting based distance relaying scheme finds limitation in protecting such compensated lines. Significant research has been carried out in recent years to develop new algorithms and methods to address the problem. This paper presents a comprehensive review of recent developments in the protection of TCSC/UPFC compensated high-voltage transmission lines. The relative merits and demerits of each of the available methods are also presented for comparison. Prior to detail review, the impact of TCSC/UPFC on distance protection is evaluated by using data generated through EMTDC/ PSCAD on a 400 kV two-bus test power system. This study can be useful to both academic researchers and practicing engineers to gain insight on the protection of FACTS compensated transmission lines and for further development of newer algorithms. 2 FACTS compensated high-voltage transmission lines: protection challenges The basic configuration and the different operating modes of TCSC and UPFC controllers and their impacts on the distance protection are well documented in [10-16], respectively. However, for the sake of completeness, in this section, the impact of TCSC/UPFC compensated transmission lines on the performance of distance relay is evaluated by using data simulated through EMTDC/ PSCAD on a 400 kV test power system.

An unblocking assistance to distance relays protecting TCSC compensated transmission lines during power swing

“…1 Let us consider a fault with resistance R F is occurred in n per unit distance of line 7-8 as shown in Figure 2A. Using symmetrical component method of fault analysis, the apparent impedance seen at relay R 7-8 for three-phase fault (LLL-fault), single-line-to-ground fault (LG-fault), and line-to-line/double-line-to-ground fault (LL/ LLG-fault) can be expressed as in Equations (1), (2), and (3), respectively. Using symmetrical component method of fault analysis, the apparent impedance seen at relay R 7-8 for three-phase fault (LLL-fault), single-line-to-ground fault (LG-fault), and line-to-line/double-line-to-ground fault (LL/ LLG-fault) can be expressed as in Equations (1), (2), and (3), respectively.…”

“…The corresponding equivalent circuit diagram of the faulted network is shown in Figure 2B. 31 The positive-sequence, negative-sequence, and zero-sequence components of different parameters in Equations (1), (2), and (3) are represented by suffixes 1, 2, and 0, respectively. 31 The positive-sequence, negative-sequence, and zero-sequence components of different parameters in Equations (1), (2), and (3) are represented by suffixes 1, 2, and 0, respectively.…”

“…In recent years, the use of TCSC compensated lines has been increased compared with FSC compensated lines due to numerous technical benefits such as dynamic power flow control, mitigation of subsynchronous resonance, reduction of system losses, transient stability, etc. 2 The TCSC operates mainly in capacitive mode during both steady state and power swing conditions. However, during the fault condition, the TCSC swifts to inductive mode of operation for limiting the fault current.…”

“…The corresponding equivalent circuit diagram of the faulted network is shown in Figure 2B. Using symmetrical component method of fault analysis, the apparent impedance seen at relay R 7-8 for three-phase fault (LLL-fault), single-line-to-ground fault (LG-fault), and line-to-line/double-line-to-ground fault (LL/ LLG-fault) can be expressed as in Equations (1), (2), and (3), respectively. 31 The positive-sequence, negative-sequence, and zero-sequence components of different parameters in Equations (1), (2), and (3) are represented by suffixes 1, 2, and 0, respectively.…”

“…1 In recent years, the use of series compensated devices has been increased in transmission networks worldwide to fulfill the increasing electricity demand. 2,3 Series compensations are provided either using fixed series capacitors (FSCs) or thyristor controlled series capacitors (TCSCs). However, the installations of these compensating devices in transmission networks impose protection challenges to distance relays.…”