Investigation of the effects of distributed series reactors on stability of power systems

Distributed FACTS (D-FACTS) devices Distributed Series Reactors (DSR) are devices that are connected in series to the transport conductor and add a series inductive impedance to the line. These devices can correct the impedance imbalance in the power system by changing the parameters of the transmission lines. In addition to this, voltage balancing in the system also provides a higher amount of power transport, or in other words, a more efficient use of the transmission capability of the power system. The DSR is mounted on the transmission line. Each module can be triggered at a predetermined current value as well as remotely controlled. The first pilot application was carried out on High Voltage (HV) transmission conductors between 2002-2003. DSR application provides to increase the transmission limit in power systems. DSR elements have important benefits in the optimum operation of transmission lines. It allows controlling the loadability of the system without expanding the existing dimensions of the power system. Therefore, the use of DSR devices in transmission lines has been increasing in recent years and its importance has increased. In this study, the effects of DSR application on system loading, its effect on voltage stability and applicability were analyzed. DSR application was performed on Institute of Electrical and Electronics Engineers (IEEE) 6 busbar and 9 busbar test systems with PowerWorld Simulation software. In this study, it has been observed that the load rates of the lines that are overloaded in the power system decrease with the use of DSR devices. In the IEEE 6 busbar system, the overloaded (1-4) and (3-6) lines were initially 65% and 69% respectively, while when DSR devices were added to these lines, the loading rates decreased to 61% and 64%, respectively, in the final state. In the IEEE 9 busbar system, the loading rates of the overloaded (1-4), (4-5), (5-6) and (5-7) lines are 116%, 109%, 92%, and 100%, respectively, while DSR devices are added to these lines. When added, the loading rates decreased to 99%, 89%, 91% and 93%, respectively, in the last case. In addition, it has been observed that both critical power and critical voltage values generally decrease in terms of system stability. Again in this study, it was observed that the use of DSR reduces the active power losses on the overloaded lines, but increases the reactive power losses in general.