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1. Prepared by: Tarun Kumar Vishnu Yadav Prakash Gupta Shubhendra Karn Vikul Kumar Baliyan Under Guidance of Mr. Manish Srivastava ) A PROJECT ON Reduction of reactive power loss by UPFC )

2. FACT SYSTEM Flexible AC TRANSMISSION SYSTEM

3. Content:- Introductionof FACTS Need of FACTS Devices Type of Compensation Technique Type of FACTS Controller Type of FACTS Devices UPFC Simulation References

4. FACTS (Flexible AC Transmission System):- FACT devices are used in a power system network to increase the power transfer capability of transmission line and it will increase the voltage stability, transient stability, voltage regulation, reliability, thermal limits of the transmission network. Before the invention of power electronics switches, these problems were solved by connecting capacitor, reactor, or synchronous generator with the help of mechanical switches. But there is a lot of problems to use the mechanical switches. It has a very slow response and there is a problem of wear and tear of mechanical switches. So, these are not reliable ways to increase the controllability and stability of the transmission line. After the invention of power electronics switch like thyristor that can be used for the high voltage applications, power electronics bases FACTS controllers are developed. After the invention of power electronics switch like thyristor that can be used for the high voltage applications, power electronics bases FACTS controllers are developed.

5. We know that, Apparent power =√ (Active power + Reactive Power) From this equation we can say that Reactive Power depend upon the apparent power. if Reactive power decreases than apparent power decreases. From , Power triangle Cos θ = Active power / Apparent power Hence, if apparent power decreases than then power factor( cos θ ) also increased.

6. NEED OF FACT SYSTEM Enhance controllability and power transfer capability. High speed response. Control line impedance, voltage and optimum power flow. Increase system security. Provides greater flexibility. Balance reactive power voltage , transmission loss). Increase the stability of power transmission over long distance.

7. Compensation Technique:- Series Compensation Shunt Compensation Series compensation is the method of improving the system voltage by connecting a capacitor in series with the transmission line .

8. The power transfer capacity of a transmission line without using compensation device; Where, V1 = Sending end voltage V2 = Receiving end voltage X = Inductive reactance of transmission line δ = Phase angle between V1 and V2 P = Power transferred per phase

9. Hence, it is clear that, if we use the series compensation devices, approximately 50% more power can be transfer. After using the compensation device, the power transfer capacity is;

10. Shunt Compensation:- In this technique, a capacitor are connected in shunt(parallel) to the transmission line. This method is used to improve power factor . When ever an inductive load is connected to the transmission line power factor lags because of lagging load current. To compensate a shunt capacitor is connected which draws current leading the source voltage. If the capacitance of the line increases, the receiving end voltage will increase

11. UPFC Unified Power Flow Controller

12. UPFC- Unified Power Flow Controller STATCOM SSSC

13. A combination of static synchronous compensator(STATCOM) and a static series compensator(SSSC) which are coupled through a DC link to allow bi-directional flow of real/reactive power between the series output terminals of the SSSC and the shut output terminals of the STATCOM. The main advantage of the UPFC is to control both active & reactive power flows in the transmission line . If there are any disturbances of faults in the source side , the UPFC will not work. The UPFC operate only under balance sine wave source. The controllable parameters of the UPFC are reactance in the line , phase angle and voltage . The UPFC allows to suppress power system oscillation improving the transient stability of the power system. The UPFC controller is made of the combination of STATCOM & SSSC .

14. Static Synchronous Compensator(STATCOM):- STATCOM or Static Synchronous Compensator is a power electronic device using force commutated devices like IGBT, GTO etc. to control the reactive power flow through a power network and thereby increasing the stability of power network. STATCOM is a shunt device i.e. it is connected in shunt with the line. A Static Synchronous Compensator (STATCOM) is also known as a Static Synchronous Condenser (STATCON). It is a member of the Flexible AC Transmission System (FACTS) family of devices. The terms Synchronous in STATCOM mean that it can either absorb or generate reactive power in synchronization with the demand to stabilize the voltage of the power network.

15. Block Diagram & Circuit Diagram of STATCOM

16. Voltage Source Converter, VSC It’s convert the DC input voltage to an AC output voltage. Two of the common VSC types are as below.  Square-wave Inverters using Gate Turn-Off Thyristors : In this type of VSC, output AC voltage is controlled by changing the DC capacitor input voltage, as the fundamental component of the converter output voltage is proportional to the DC voltage. PWM Inverters using Insulated Gate Bipolar Transistors (IGBT): It uses Pulse Width Modulation (PWM) technique to create a sinusoidal waveform from a DC voltage source with a typical chopping frequency of a few kHz. In contrast to the GTO-based type, the IGBT-based VSC utilizes a fixed DC voltage and varies its output AC voltage by changing the modulation index of the PWM modulator. DC Capacitor DC Capacitor is used to supply constant DC voltage to the voltage source converter, VSC. Inductive Reactance A Transformer is connected between the output of VSC and Power System. Transformer basically acts as a coupling medium. In addition, Transformer neutralize harmonics contained in the square waves produced by VSC.   Harmonic Filter Harmonic Filter attenuates the harmonics and other high frequency components due to the VSC.

17. Static Series Compensator (SSSC):- Static synchronous series compensator works like the STATCOM. It is a modern FACTS device that employs a voltage source converter connected in series to a transmission line through a transformer. The SSSC operates like a controllable series capacitor and series inductor. The primary difference is that its injected voltage is not related to the line intensity and can be managed independently. This feature allows the SSSC to work satisfactorily with high loads as well as with lower loads. It is able to transfer both active and reactive power to the system, permitting it to compensate for the resistive and reactive voltage drops – maintaining high effective X/R that is independent of the degree of series compensation. However, this is costly as a relatively large energy source is required.

18. The Static Synchronous Series Compensator has three basic components:  Voltage Source Converter (VSC) – main component. Transformer – couples the SSSC to the transmission line. Energy Source – provides voltage across the DC capacitor and compensate for device losses

19. Simulation Model:

20. Results: The figure above shows the curve when the UPFC is not connected to the transmission line. At this time, the apparent power is 1.89E+08 Fig. Graph when UPFC not connected with tx . Line

21. The figure above shows the curve when the UPFC is connected to a transmission line. At this time, the apparent power is 1.59E+08 Fig. Graph when UPFC connected with tx . Line

22. Comparison Chart : CONCLUSION : In this article, the power system is designed with UPFC devices to reduce reactive power loss. In the UPFC device, we used a combination of SSSC and STATCOM. With the help of these devices, we inject additional power into the transmission lines. Reduce reactive power loss, thereby reducing apparent power and improving power factor

23. References: [1] Proposed terms and definitions for flexible AC transmission system (FACTS), IEEE Transactions on power Delivery, Volume 12, Issue 4, October 1997, pp. 1848-1853. Doi: 10.1109/61.634216. [2] Voltage Stability Improvement using Thyristor Controlled Series Capacitor (TCSC) based on LMN and VCPI Stability Indices, Venu Yarlagadda, Dr. B. V. Sankar Ram, Dr. K. R. M. Rao. [3] Simulation of real and reactive power flow control with UPFC connected to a transmission line., IS. Tara Kalyani, 2G. Tulasiram Das. [4] Implementation of Unified Power Flow Controller (UPFC) for Power Quality Improvement in IEEE 14-Bus System, Arup Ratan Bhowmik 1, Champa Nandi2. [5] Vibhor Gupta, “Study and Effects of UPFC and its Control System for Power Flow Control and Voltage Injection in a Power System”, International Journal of Engineering Science and Technolgy vol.2(7), 2010, pp-2558-2566. [6] Distributed generation and FACTS Technology – Wikipedia, the free encyclopaedia .