07-04-2017, 04:13 PM
With the increasing demand for electricity, sometimes, it is not possible to erect new lines to deal with the situation. The flexible AC transmission system (FACTS) uses thyristor controlled devices and optimally utilizes the existing electrical network. FACTS devices play an important role in the control of active and reactive power flow to the mains, and therefore both system voltage fluctuations and transient stability. This paper proposes the Unified Power Flow Controller (UPFC) as a strong candidate to provide complete dynamic control of power transmission operation parameters: voltages, line impedance and phase angle under normal and fault conditions. Simulink composite model for 4 bus system equipped with UPFC to illustrate the control features of this device and its influence to increase power transfer and improve system stability. The digital simulation using MATLAB / SIMULINK is done with this model and the results are presented.
FACTS can perform all reactive power control and voltage control objectives within the transmission and distribution networks and at the load terminals. Several flexible AC systems FACTS schemes are in use today. One of the most important FACTS devices is the Unified Power Flow Controller (UPFC), which is used to investigate its effect on load flow and loss reduction in the power system. The UPFC is a combination of a static synchronous series (STATCOM) compensator and a static synchronous series compensator (SSSC), which are coupled through a common DC link. The UPFC is a device that can simultaneously control all three parameters of line power flow which are line impedance, voltage and phase angle. The UPFC improves regulation of terminal voltage, capacitor compensation in series and regulation of the angle of transmission. The main objectives of this work are to develop a new basic control scheme and an integrated analysis for a unified power flow controller (UPFC) to develop also the MATLAB program that simulates the UPFC and its power system action. This developed technique proved to be very effective and will allow engineers to study and investigate how the UPFC can affect the transmission system by using series voltage and shunt current injection. It was demonstrated that the UPFC can improve the characteristics of the system and provides the best transient and dynamic stability. The power factor can be greatly improved. Many cases are investigated and studied as the application of the UPFC to control the voltage and power flow. The cases are tested for the same simulated power system but with different types of loads and different voltages of the system. In all cases, the system performance was analyzed, tested and studied to indicate voltages, currents and power and was shown to be satisfactory.
FACTS can perform all reactive power control and voltage control objectives within the transmission and distribution networks and at the load terminals. Several flexible AC systems FACTS schemes are in use today. One of the most important FACTS devices is the Unified Power Flow Controller (UPFC), which is used to investigate its effect on load flow and loss reduction in the power system. The UPFC is a combination of a static synchronous series (STATCOM) compensator and a static synchronous series compensator (SSSC), which are coupled through a common DC link. The UPFC is a device that can simultaneously control all three parameters of line power flow which are line impedance, voltage and phase angle. The UPFC improves regulation of terminal voltage, capacitor compensation in series and regulation of the angle of transmission. The main objectives of this work are to develop a new basic control scheme and an integrated analysis for a unified power flow controller (UPFC) to develop also the MATLAB program that simulates the UPFC and its power system action. This developed technique proved to be very effective and will allow engineers to study and investigate how the UPFC can affect the transmission system by using series voltage and shunt current injection. It was demonstrated that the UPFC can improve the characteristics of the system and provides the best transient and dynamic stability. The power factor can be greatly improved. Many cases are investigated and studied as the application of the UPFC to control the voltage and power flow. The cases are tested for the same simulated power system but with different types of loads and different voltages of the system. In all cases, the system performance was analyzed, tested and studied to indicate voltages, currents and power and was shown to be satisfactory.