Unified Power Flow Controller (upfc)

Electricity interruption gives rise to a complete disorder in the society and is therefore unappreciated and highly criticized. Consequently, it becomes a great concern for national and/or private energy companies to conduct their power systems under severe requirements. These companies are asked to ovoid failures that induce power oscillation, voltage drop and high frequency deviations because these phenomena can produce the loss of the system integrity by rapid voltage collapse or any transient stability mechanism. New technology alternatives such as FACTS (flexible alternative current transport systems) can positively support conventional control systems such as PSSs (power system stabilizer), AVRs (automatic voltage regulator) and TGs (turbine governor). But at the same time, it is to recognize that power system control becomes more complicate and requires suitable global strategies. The paper deals with this problem and aims to show that UPFC is a suitable device in particular ...

The Unified Power Flow Controller (UPFC) is the most versatile and complex power electronic equipment that has emerged for the control and optimization of power flow in electrical power transmission system. This paper presents real and reactive power flow control through a transmission line by placing UPFC at the sending end using computer simulation. When no UPFC is installed, real and reactive power through the transmission line can not be controlled. This paper presents control and performance of UPFC intended for installation on that transmission line to control power flow. A control system which enables the UPFC to follow the changes in reference values like AC voltage, DC voltage and angle order of the series voltage source converter is simulated. In this control system, a generalized pulse width modulation technique is used to generate firing pulses for both the converters. Installing the UPFC makes it possible to control an amount of active power flowing through the line. Si...

For solving Optimal Power Flow (OPF) issues in a Transmission Line, a Unified Power Flow Controller (UPFC) is used with Search Group Algorithm (SGA). UPFC is a FACTS device is connected in series with the transmission line. In this work an IEEE 30 bus system has been considered for optimal power flow analysis. Newton Raphson technique is used for solving nonlinear equation of the proposed model.

Better power quality is required for various electronics and electrical devices to perform efficiently. Various devices are available for power quality improvement. Different devices are suitable for different power quality disturbances or deviations such as Distribution Static Synchronous Compensator (DSTATCOM), Static VAR Compensator (SVC), Dynamic Voltage Restorer (DVR) and Unified Power Quality Compensator (UPQC) for the improvement of power quality in manufacturing industries. UPQC is the recent versatile device which can correct different power quality disturbances simultaneously such as harmonics, voltage sag, voltage swell, voltage regulation, load unbalancing and power factor improvement in 3-phase distribution system. UPQC is one of the best power device used to compensate both source and load side problems, which is a combination of series Active power filter (APF) and shunt APF. Various control techniques are utilised for proper operation of UPQC such as p-q theory, d-q theory, fuzzy logic control, PI control, hysteresis control etc. This paper presents different control techniques of UPQC.

One of the best flexible AC transmission system (FACTS) is unified power flow controller (UPFC). As it gets more benefit from both real and reactive power transfer, it is used in power system for controlling the transmitted power. The UPFC controls the power on the transmission side of the power system. When the real as well as reactive power is set the UPFC tries to follow the command by using the proportional and integral (PI) controller. But in some power systems the PI controllers cannot produce the proper power due to the power oscillations. These oscillations are created due to PI controller properties. In this paper the PI controller is replaced with the particle swarm optimization tuned PI controller (PSO-PI). It minimizes the power oscillations by using the objective function. The MATLAB 2017b is used to demonstrate the power transfer curves and the voltages. The IEEE 9 bus system is being used as a reference system.

This paper presents a new component within the flexible ac-transmission system (FACTS) family, called distributed power-flow controller (DPFC). The DPFC is derived from the unified power-flow controller (UPFC). The DPFC can be considered as a UPFC with an eliminated common dc link. The active power exchange between the shunt and series converters, which is through the common dc link in

This paper considers the impact of the static series synchronous compensator (SSSC) and the Unified Power Flow Controller (UPFC) on stability of the wind farm based of Doubly Fed Induction Generator (DFIG) which are connected to power system, after a severe disturbance occurrence. The comparison is made between the performances of the wind farm equipped by SSSC and UPFC to improve the wind farm stability during and after fault. The simulation result shows both of the devices can enhance the system stability during and after disturbance, especially when the network is weak. It is shown that the UPFC have a much better performance as compared to SSSC to improve wind farm stability. Matlab/simulink is used for the work.

In this paper, an innovative technique with a new concept of transformer-less unified power flow controller (UPFC) is implemented. The construction of the conventional UPFC that consists of two back-to-back inverters which results in complexity and bulkiness which involves the transformers which are complication for isolation & attaining high power rating with required output waveforms. To reduce a above problem to a certain extent, a innovative transformer-less UPFC based on less complex configuration with two cascade multilevel inverters (CMIs) has been proposed. Unified power flow controller (UPFC) has been the most versatile Flexible AC Transmission System (FACTS) device due to its ability to control real and reactive power 80w on transmission lines while controlling the voltage of the bus to which it is connected. UPFC being a multi-variable power system controller it is necessary to analyze its effect on power system operation. The new UPFC offers several merits over the traditional technology, such as Transformer-less, Light weight, High efficiency, Low cost & Fast dynamic response. This paper mainly highlights the modulation and control for this innovative transformer-less UPFC, involving desired fundamental frequency modulation (FFM) for low total harmonic distortion (THD), independent active and reactive power control over the transmission line, dc-link voltage balance control, etc. The unique capabilities of the UPFC in multiple line compensation are integrated into a generalized power flow controller that is able to maintain prescribed, and independently controllable, real power & reactive power flow in the line. UPFC simply controls the magnitude and angular position of the injected voltage in real time so as to maintain or vary the real and reactive power flow in the line to satisfy load demand & system operating conditions. UPFC can control various power system parameters, such as bus voltages and line flows. The impact of UPFC control modes and settings on the power system reliability has not been addressed sufficiently yet. Cascade multilevel inverters has been proposed to have an overview of producing the light weight STATCOM's which enhances the power quality at the output levels.When the multilevel converter is applied to STATCOM, each of the cascaded H-bridge converters should be equipped with a galvanically isolated and floating dc capacitor without any power source or circuit. This enables to eliminate a bulky, heavy, and costly line-frequency transformer from the cascade STATCOM. When no UPFC is installed, interruption of either three-phase line due to a fault reduces an active power flow to half, because the line impedance becomes double before the interruption. Installing the UPFC makes it possible to control an amount of active power flowing through the transmission system. Results has been shown through MATLAB Simulink

The objective of this paper is to reduce the power loss and to improve the voltage profile in radial distribution system. Fuzzy and particle swarm optimization algorithm is a two-stage methodology used for placement and sizing of UPFC in this paper. To show the effectiveness of the same a complete result analysis is carried out on 33 and 69 bus systems. Power loss and voltages are calculated for the optimal locations based on fuzzy system. 50%, 80% 150%, overloading cases are also considered in this paper. The result analysis shows that the two-stage methodology effectively improves the voltages and reduces the power loss of the system.

Recently it has been shown that it is possible to design a power system stabilizer (PSS) as well as an unified power flow controller (UPFC) controller using a non-linear multi-machine system model in conjunction with Lyapunov's direct method. In this paper the features of two controllers implementing the proposed control laws have been compared: the PSS constitutes a supplementary loop to the main automatic voltage regulator (AVR) and UPFC controller. Theoretical analysis is supported by the results of eigenvalues analysis and simulations tests, which highlighted the differences between the actions of compared controllers. The tests performed on a multi-machine system model have shown a good performance of both proposed controllers.

Abstract Flexible Alternating Current Transmission Systems (FACTS) devices have been proposed to be effective for controlling power flow and regulating bus voltage in electrical power systems, resulting in an increased transfer capability, low system losses and ...

According to growth of electricity demand and the increased number of non-linear loads in power grids, providing a high quality electrical power should be considered. In this paper, voltage sag and swell of the power quality issues are studied and distributed power flow controller (DPFC) is used to mitigate the voltage deviation and improve power quality. The DPFC is a new FACTS device, which its structure is similar to unified power flow controller (UPFC). In spite of UPFC, in DPFC the common dc-link between the shunt and series converters is eliminated and three-phase series converter is divided to several single-phase series distributed converters through the line. The case study contains a DPFC sited in a single-machine infinite bus power system including two parallel transmission lines, which simulated in MATLAB/Simulink environment. The presented simulation results validate the DPFC ability to improve the power quality.

The work of this paper is a hopeful attempt to rectify poor damping issue of the Iraqi National Super Grid System (INSGS). Without proper damping control these oscillations drive the system toward instability following severe disturbances. In this paper, a Unified Power Flow Controller (UPFC)-based damping controller was proposed to improve the dynamic stability of the INSGS. The system with UPFC installed in different sectors was represented by the linearized Phillips-Heffron generator model. The excitation phase angle was used as input control signal to the UPFC. PI controller was applied to the design of the damping controller. The power system with the UPFC was tested in different sectors under different loading conditions and disturbances using the MATLAB Simulink program. Simulation results demonstrated that the UPFC can work successfully with INSGS in damping low-frequency oscillations and improving the dynamic stability and voltage profiles. In addition, the proposed approac...

The capability of regulating power flow in Nigerian Grid System using UPFC is the main focus in this paper. Consequently, three control methods, namely, voltage control through shunt compensation, real power flow control through quadrature voltage injection and reactive power flow control through in-phase voltage injection for the UPFC were examined in order to improve the transient stability of the power system. The quadrature voltage control was found to be effective in reducing the transient swings whereas in-phase voltage control was effective in improving the transient stability margin. Finally, the overall performance of the UPFC was evaluated in a singlemachine infinite bus system by nonlinear simulations, and results obtained showed the effectiveness of the controller in improving the dynamic stability of the system and provide better damping to electromechanical oscillations.

The maintenance and reliability of the power system has become a major aspect of study. The existing network is mechanically controlled, though we provide control and protection system which are electronics, computer, microcontroller based but the signal which is provided to the circuit where final action is carried out is completely mechanically controlled which reduced efficiency of the system. The solution is the use of FACTS devices especially the use of unified power flow controller (UPFC).The FACTS is nothing but to make system more flexible to adapt the variation due to occurrence of faults. In this paper the study of UPFC with its mathematical modeling. Second, the operation of control system used in its converters is also studied. Finally by help of modeling of a power system in MATLAB and by installing UPFC in transmission link, its use as power flow controller and voltage injection is seen. Conclusion is made on different results i.e. voltage profile, phase angle and active and reactive power to see the benefit of UPFC in power system. The paper explains the basic theory and operating characteristics of the unified power flow controller with mathematical modeling of photovoltaic system and then this model is implemented to three phase system. Keywords-FACTS; Photovoltaic power station; power flow analyze; unified power flow controller (UPFC)

Page 1. Comparison of Power flow control: TCSC versus UPFC Samina E. Mubeen, RK Nema, and Gayatri Agnihotri ... Dr.Gayatri Agnihotri is Professor in Department of Electrical Engineering MANIT Bhopal India (e-mail:gayatrial(arediffmail.com). capacitors and inductors. ...

The work of this paper is a hopeful attempt to rectify poor damping issue of the Iraqi National Super Grid System (INSGS). Without proper damping control these oscillations drive the system toward instability following severe disturbances. In this paper, a Unified Power Flow Controller (UPFC)-based damping controller was proposed to improve the dynamic stability of the INSGS. The system with UPFC installed in different sectors was represented by the linearized Phillips-Heffron generator model. The excitation phase angle was used as input control signal to the UPFC. PI controller was applied to the design of the damping controller. The power system with the UPFC was tested in different sectors under different loading conditions and disturbances using the MATLAB Simulink program. Simulation results demonstrated that the UPFC can work successfully with INSGS in damping low-frequency oscillations and improving the dynamic stability and voltage profiles. In addition, the proposed approac...

Abstract-This paper presents a novel method for optimal location of FACTS devices in a multi machine power system using Genetic Algorithm(GA). Using the proposed method, the location of FACTS controllers, their type and rated values are optimized simultaneously. Among ...

After a brief review of perturbation technique, using this method an approach is developed to represent and study the behavior of nonlinear dynamic power systems. For the first time in this field, perturbation technique is applied to obtain an approximate closed form expression for the zero input response of stressed power systems. In order to show the superiority of the

DPFC is proposed in the present work to improve voltage stability of fourteen bus system during line interruption. The voltage across the load decreases due to the interruption of the line. State space method is used to calculate Line currents and bus voltages. The ability of DPFC to bring voltage, real power and reactive power to normal level is presented in this paper. The simulation results for healthy system, line interrupted system without DPFC and with DPFC are presented. The results of comparative study are presented to show the improvement in power quality. The simulation studies indicate that the power flow with DPFC during line outage is almost equal to the power during healthy condition.