Feasibility of increasing power transmission capacity of the Iringa-Dodoma transmission line using static synchronous series compensator

Enhancement of power transfer capability for Iringa – Dodoma transmission line is an important issue due to the fact that there is increase in electrical power demand in central and north regions of Tanzania and also because of the growth of economic activities taking place in those regions and the development of the mining sector in Northwest Regions of Tanzania. Peak demand for Central and North Regions of Tanzania was studied. From year 2008 to 2012 the peak demand increased from 208.7 MW to 237.63 MW. The increase in demand of electricity energy led to load shedding on the North grid. This study proposed Static Synchronous Series Compensator (SSSC) to control power flow through a transmission line. Among the series Flexible Alternating Current Transmission Systems (FACTS) controllers, SSSC is the most effective device due to its capability of controlling power flow in transmission lines. Neutral Point Clamped (NPC) three phase, three level voltage source converter was designed using Insulated gate bipolar transistor (IGBTs). Also, the control circuit of voltage source converter was designed using d-q-0 algorithm and Pulse Width Modulation (PWM) control technique. The single line diagram of transmission line connected in series with SSSC using coupling transformer was modeled in MATLAB/Simulink. The model was simulated in mat lab – Power System Block (PSB) set. The line current of transmission line increased from 600 A to 800 A (33.33%). The active power at receiving end of transmission line was increased from 181 MW to 270 MW. The simulation results showed that the SSSC performance was satisfactory in increasing power transfer capacity.