© 2018 JETIR November 2018, Volume 5, Issue 11 www.jetir.org (ISSN-2349-5162) JETIRK006028 Journal of Emerging Technologies and Innovative Research (JETIR) www.jetir.org 188 Modelling of Static Synchronous Series Compensator (SSSC) to Address the Issues of AC Transmission Network Ruchirkumar Mehta 1 *, Falgunibahen Taral 2 , A. R. Patel 3 , Dr. N. G. Mishra 4 , 1 Electrical Engineering Department, Birla Vishvakarma Mahavidyalaya, India 2 Electrical Engineering Department, Birla Vishvakarma Mahavidyalaya, India 3 Electrical Engineering Department, Birla Vishvakarma Mahavidyalaya, India 4 Electrical Engineering Department, Birla Vishvakarma Mahavidyalaya, India Abstract Simulation and modelling of Static Synchronous Series Compensator (SSSC) is portrayed for VAR compensation in Flexible Alternating Current Transmission System in this paper. MATLAB software is utilized for simulation purpose of reactive power compensation using SSSC. The AC transmission network requires VAR compensators such as SSSC which improves various other aspects of the power system as well. The SSSC controls the injecting voltage in quadrature with line current into the system. It provides voltage regulation by compensating reactive power of the system. The SSSC comprises of Voltage Source Inverter (VSI), PI controller, PWM generator and three-phase locked loop. Keywords: FACTS devices, Static Synchronous Series Compensator (SSSC), Transmission line, Reactive power compensation INTRODUCTION The advancement of Flexible AC Transmission System is started by the Electric Power Research Institute (EPRI). In FACTS, power flow is dynamically controlled by power electronic devices. The goals of FACTS are to enhance transmission capacity of line and control the power flow on indicated paths [1, 2]. The development & commercial presence of fast power-semiconductor devices like IGBT, Gate Turn- Off thyristor (GTO) has made fast controllable reactive power sources possible. The advancement of FACTS switching technologies e.g., STATCOM, SSSC, UPFC etc. is offering considerable merits over existing techniques. The voltage source inverter (VSI) are getting acceptance as the new emerging devices. They offer far more flexible reactive power control compared to conventional reactive power compensation devices like Thyristor Switched Capacitor (TSC), Thyristor Controlled Reactor (TCR), Thyristor Controlled Series Capacitor (TCSC) and Thyristor Switched Series Capacitor (TSSC) etc. The Static Synchronous Series Compensator (SSSC) comprises of PI controller, Voltage Source Converter, IGBT or GTO thyristor switches having intrinsic turn-off capability, coupling transformer and a DC capacitor. The DC capacitor is used as energy storage system. A DC battery can also be used in lieu of DC capacitor [3]. Nowadays, the transmission lines are being heavily loaded due to increase in load demand. Reactive power compensation helps in enhancing power transfer capability of the transmission line. It can also be used for improving the voltage regulation of the power system [4]. In High Voltage transmission lines, the reactance to resistance XL/R ratio is between ranges of 3 to 10. When capacitive compensation increases this ratio is further reduced. This will limit the active power transfer due to increase in VAR absorption, line losses and possible voltage depression [5]. SSSC has negligible output impedance at frequencies other than fundamental frequency. Therefore, the converter allows only the positive sequence component of voltage and current through it under balanced condition. There is no problem of sub-synchronous resonance (SSR) below synchronous