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Impact of FACTS Devices on Transmission and Distribution System
Ali Raza Kalair, Naeem Abas, Anam Kalair, Qadeer Ul Hasan and Nasru Llah Khan

Distribution Flexible Alternating Current Transmission System (DFACTS) devices are evolving technologies to mitigate voltage sags, swells, flickers and harmonics during transient and steady state operations. Power electronics and communication technologies have made the conventional grid smart and artificial intelligence based algorithms even smarter but simulation studies based notion of applying the FACTS devices to damp the small or large scale power swings to improve steady state or transient stability looks like an unreliable notion. Modern FACTS devices include SVC, STATCOM, SSSC, UPFC, UPQC, DVR, TSC and TSR. Use of STATCOM, SSSC and UPFC requires a real time reference which suffers communication delay limitation. STATCOM and SSSC produce 4PU to 5PU high voltage and current impulses which are high enough to puncture insulators to compromise insulation coordination. Operation of STATCOM and SSSC renders protective relays ineffective and pollute the power quality. Best control systems clear 0.1 to 2Hz oscillations in the range of 2.5 to 7 seconds and protective relays operate in range of 0.05 to 0.5 seconds to clear faults. Power engineers believe the FACTS devices destabilize the power system due to their own presence therefore their use with some snubbing circuits may be limited to generation and distribution sides.

Keywords: Steady state stability, transient stability, FACTS devices, STATCOM, SSSC, UPFC

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