Hazlie Mokblis - Department of Electrical Engineering, Faculty Of Engineering. University of Malaya Kuala Lumpur, Malaysia
Khalid Mohamed Nor - Department of Electrical Engineering, Faculty Of Engineering. University of Malaya Kuala Lumpur, Malaysia

Flexible AC Transmissions System (FACTS) devices are solid-state converters that are capable of regulating various electrical parameters in transmission lines. Parameters such as impedance, current, voltage, phase angle and damping of oscillation at various frequencies can be controlled efficiently [1]. These capabilities have made FACTS devices continue to be installed in power system networks. Under the FACTS group, there are devices such as Unified Power Flow Controller (UPFC), Static Series Synchronous Compensator (SSSC), and Static Synchronous Compensator (STATCOM). UPFC is the most versatile FACTS device since it can provide active and reactive power flow control and voltage magnitude control, in any combination, simultaneously. In order to assess and analyse the impact of FACTS devices in power system network, existing software and analytical methods have to be modified to account for them. This has motivated researchers to develop suitable mathematical model and algorithm for FACTS. There are many models proposed [3,4,5]. C.R. Fuerter-Esquivel et. al. [5] proposed a new and accurate steady-state model for UPFC incorporated into an existing Newton Raphson (NR) method. A very important aspect in implementing load flow algorithms is the programming approach. In the past, load flow algorithms are implemented using the conventional function-oriented software development methodologies and structured programming techniques. Function oriented development methodology emphasise on decomposing and describing system functionality. While in structured programming technique, there is a strong coupling between the data structures and the procedures. Minor changes in system functionality and data may propagate through the whole program. Therefore, when the requirement changes such as the emergence of new technological devices, such as FACTS devices, massive code reconstruction may be required. Another programming approach is the Object Oriented programming (OOP). Object Oriented (OO) methodology models a system based on existing objects. Objects inside a system are believed more stable than system functionalities. Thus the software systems built on an object structure are more robust in the long run.

Load Flow, Fast Decoupled, Object-Oriented, UPFC, FACTS