Flexible AC Transmission Systems (FACTS) - Unified Power Flow Controller (UPFC)

Project Introduction:

My project is based on one of the latest technology in the field of power engineering and that technology is termed as “Flexible AC Transmission Systems” (FACTS). I am working on one of the most recent device of FACTS technology and that device is known as “Unified Power Flow Controller” (UPFC). This device is designed to control losses in a power transmission line by controlling three parameters of transmission line and those three parameters are voltage, phase and impedance. Thus, this device provides not only steady state stability but also dynamic stability.

 Project Details

Unified Power Flow Controller (UPFC) is one of the most recent development in the field of power engineering. Thus, it is a multi-functional and one of the most comprehensive device that have helped to solve a lot of problems associated with power transmission. This device is a combination of two previous FACTS devices; namely STATCOM (static shunt compensator) and SSSC (static synchronous series compensator). The hardware components of this device are listed below:

(i)Shunt transformer:-

Voltage from source end is coupled to UPFC through shunt transformer. This is a step down transformer which is further use to drive shunt converter.

(ii)Shunt converter:-

Shunt converter is use to convert AC injcted into it to DC. This DC power is further use to charge a capacitor. The shunt converter is primarily used to provide the active power demand of the series converter through a common dc link. The shunt converter can also generate or absorb active reactive power if it is desired, and thereby provide independent shunt reactive compensation for the line.

(iii)DC link capacitor:-

DC link capacitor is use to provide DC input to inverter. Real power is provided to inverter through this capacitor. It is used to exchange the real power between the two converters. The real power demand of SSSC is depicted as positive or negative demand at the dc link capacitor and accordingly STATCOM generates or absorbs the real power to meet the demand of SSSC.

(iv)Series inverter:-

Series inverter is use to convert DC voltage injected into it through capacitor into AC. The series inverter provides the prime function of UPFC. By using PWM principles, it generates a voltage of controllable magnitude and phase (0-360^o). This is used to regulate the AC transmission line voltage to meet the power demands at load. It supplies or absorbs the required reactive power locally and exchanges the real power as a result of series voltage injection.

(v)Series transformer:-

Series transformer is use to inject voltage through series inverter into transmissionline.