2013 International Conference on Power, Energy and Control (ICPEC) 978-1-4673-6030-2/13/$31.00 ©2013 IEEE 124 Some studies of Distributed Series FACTS Controller to control active power flow through Transmission Line Mr. Sandeep R. Gaigowal Dr. M. M. Renge Asssistant Prof. Electrical Department Prof. Electrical Department Dr. Babasaheb Ambedkar College of Engg. & Research, Nagpur, India Ramdeobaba College of Engg. & Management, Nagpur, India Abstract- Day by day energy consumption is increasing. It is an urgent need to increase power generation and hence increase in power transmission capability. There is an increasing demand of power flow control in power systems of the future and FACTS devices are the most suitable devices to control power flow. However cost and reliability are the main issues that create hurdles in widespread application of FACTS Devices. Distributed-series FACTS Controller gives an opportunity to realize cost effective power flow control. In this Paper some studies are presented on Distributed series FACTS controller to control active power flow. Multilevel Inverter topologies are studied for Distributed FACTS Controller. Index Terms- Flexible AC Transmission System (FACTS), Distributed FACTS, Distributed Static Series Compensator (DSSC), Distributed Series Facts Controllers (DPFC), Multilevel Inverter (MLI) I. INTRODUCTION Day by day power demand is increasing. To fulfil increased demand, it is an urgent need to increase power generation and hence increase in power transmission capability. With increasing load demand, hence increase in power generation and transmission, power system becomes more and more complex, as a result, in some cases Transmission Line becomes overloaded (above thermal limit) and in other cases it becomes under loaded though its thermal limit capacity is not reached. It may lead to uncontrolled power flows; and excessive reactive power in the system, thus the full potential of transmission interconnections is not utilized. There is a need to shift a power from overloaded line to other parallel path. Accordingly new transmission line erection is needed. But it is costly and difficult due to land acquisition problem, environmental problems etc. and it is time consuming also. The possible solution is to optimize the utilization of the existing network and to boost the transmitted power upto the thermal limit of the network. One solution to the problem of managing power flow on transmission lines is by use of power electronics based FACTS devices. Flexible AC Transmission System is defined by IEEE as ‘a power electronic based system and other static equipment that provide control of one or more AC Transmission system parameters to enhance controllability and increase power transfer capability’[1]. Power flow is controlled by adjusting the parameters of a system, such as voltage magnitude, line impedance and transmission angle. FACTS Power flow controller can be divided as series controller, shunt controller and combined series-shunt controller. Switching power converters are the basic building block of a new generation FACTS controllers. FACTS devices allow control of power flows on ac power systems through the use of large power converters. Compared with mechanically switched control of the transmission system, power electronics based FACTS devices are faster and more flexible. A static synchronous series compensator (SSSC) is a series FACTS controller uses a series voltage source converter (VSC) equipped with an energy storage. SSSC injects a voltage with controllable magnitude and phase angle in quadrature with the transmission line current controls active power flow. SSSC has a capability to provide both capacitive and inductive compensation [1][2]. Recent research has been focused on designing and realizing cost effective FACTS device by applying distributed concept instead of the conventional lumped solution. Distributed Static Series Compensator (DSSC) is a D-FACTS device light in weight & it can be attached directly to the existing transmission line allowing active power flow control [3][4]. DSSC can be used to realize effective impedance variation and it can