Review of Transient Stability Enhancement in Multi-Machine Power System by using Various Types of PSS & FACT s Devices

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1 Review of Transient Stability Enhancement in Multi-Machine Power System by using Various Types of PSS & FACT s Devices G. B. Jadhav 1, Dr. C. B. Bangal 2, Dr. Sanjeet Kanungo 3 1 Ph.D. Scholar, Dr.Babasaheb Ambedkar Marathwada University, Aurangabad, Maharashtra 2 Professor & Principal, RMD, Shinhgad School of Engineering, Pune, Maharashtra 3 Professor & Program Chair Marine Engineering, Tolani Maritme Institute, Pune, Maharashtra gyandevj@tmi.tolani.edu, charudatta_bangal@yahoo.com, sanjeetk@tmi.tolani.edu Abstract: This paper presents review of various techniques used for enhancement of power system stability. Various combinations of PSS s and FACT s devices such as the SVCbased PID damping controller and PSS, STATCOM controller, the SVC and the generic/multiband PSS, MultiBand PSS, Dual input PSS, PSS and TCSC controllers, FLPSS, UPFC and PSS and the MB-PSS which are used for enhancing transient stability in power system are reviewed in this paper. The information collected in this paper is sufficient for finding out relevant references in the field of power system stability. Keywords: Transient Stability, FACTS controller, PSS. 68 I. INTRODUCTION The power system is a highly nonlinear system that operates in a constantly changing environment; loads, generator outputs and key operating parameters change continually. When subjected to a disturbance, the stability of the system depends on the initial operating condition as well as the nature of the disturbance. Increasingly complex modern power systems require stability, especially for transient and small disturbances. Transient stability plays a major role in stability during fault and large disturbance.[26] The change in electromagnetic torque of a synchronous machine following a perturbation can be resolved into two components: Synchronizing torque component, in phase with rotor angle deviation. Damping torque component, in phase with the speed deviation. System stability depends on the existence of both components of torque for each of the synchronous machines. Lack of sufficient synchronizing torque results in aperiodic or nonoscillatory instability, whereas lack of damping torque results in oscillatory instability. For convenience in analysis and for gaining useful insight into the nature of stability problems, it is useful to characterize rotor angle stability in terms of the following two subcategories: Small-disturbance (or small-signal) rotor angle stability is concerned with the ability of the power system to maintain synchronism under small disturbances. In today s power systems, small-disturbance rotor angle stability problem is usually associated with insufficient damping of oscillations. The aperiodic instability problem has been largely eliminated by use of continuously acting generator voltage regulators; however, this problem can still occur when generators operate with constant excitation when subjected to the actions of excitation limiters (field current limiters). Small-disturbance rotor angle stability problems may be either local or global in nature. The time frame of interest in small-disturbance stability studies is on the order of 10 to 20 seconds following a disturbance. Large-disturbance rotor angle stability or transient stability, as it is commonly referred to, is concerned with the ability of the power system to maintain synchronism when subjected to a severe disturbance, such as a short circuit on a transmission line. The resulting system response involves large excursions of generator rotor angles and is influenced by the nonlinear power-angle relationship. Transient stability depends on both the initial operating state of the system and the severity of the disturbance. Instability is usually in the form of aperiodic angular separation due to insufficient synchronizing torque, manifesting as first swing instability. However, in large power systems, transient instability may not always occur as first swing instability associated with a single mode; it could be a result of superposition of a slow interarea swing mode and a local-plant swing mode causing a large excursion of rotor angle beyond the first swing.it could also be a result of nonlinear effects affecting a single mode causing instability beyond the first swing. - The time frame of interest in transient stability studies is usually 3 to 5 seconds following the disturbance. It may extend to seconds for very large systems with dominant inter-area swings.[1]-[2]-[3] Mitigation of Transient Stability Problem: The control actions at generator end to enhance the system stability are either in terms of excitation system or power system stabilizers or at mechanical end of power plants. Fig.1 show the general structure of primary control system to enhanced transient stability at generator end side in the system [19].

2 Tm = mechanical torque in per unit; Te = electrical torque in per unit; H = combined turbogenerator inertia constant expressed in megawatt seconds per megavolt ampere. Fig. 1. Physical Structures of Basic Control Scheme [19] Negative Damping Due to Voltage Regulator: It is generally recognized that the normal feedback control actions of voltage regulators and speed governors on generating units have the potential of contributing negative damping which can cause undamped modes of dynamic oscillations.[3]-[4] where Ks = synchronizing coefficient; KD = damping coefficient; Δδ = rotor angle change; ω = angular speed of rotor; Δ = change. From equation (2), it can be seen that for positive values of Ks, the synchronizing-torque component opposes changes in the rotor angle from the equilibrium point (i.e., an increase in rotor angle will lead to a net decelerating torque, causing the unit to slow down, relative to the power system, until the rotor angle is restored to its equilibrium point Δδ = 0). Similarly, for positive values of KD, the damping-torque component opposes changes in the rotor speed from the steady-state operating point. A generator will remain stable as long as there are sufficient positive synchronizing and damping torques acting on its rotor for all operating conditions. (2) Fig. 2. Block Diagram of Generator Under Voltage Regulator Any change in the terminal voltage magnitude E T from the reference set point provides an error signal (Ae) to the voltage regulator, which calls for a change in excitation level. The major delay in this voltage feedback loop is due to the response in machine flux (Eq) for a change in generator field voltage (E FD ) this delay is due to the large inductance of the generator field winding. For a generator on-line, this delay can be represented by a time constant Tq which is usually about 2 seconds. [3],[4] The swing equation: where δ = rotor angle in radians; ω O = angular speed of rotor (the base or rated value ω O = 377 rad/s); (1) Fig. 3. Response of Speed and Angle to Small Disturbances. [4] The relationship between rotor speed and electrical power following small disturbances is shown in Fig.3. A number of factors can influence the damping coefficient of a synchronous generator, including the generator s design, the strength of the machine s interconnection to the grid, and the setting of the excitation system. While many units have adequate damping coefficients for normal operating conditions, they may experience a significant reduction in the value of KD following transmission outages, leading to unacceptably low damping ratios. In extreme situations, the damping coefficient may become negative, causing the electromechanical oscillations to grow and, eventually, causing a loss of synchronism. This form of instability is normally referred to as dynamic.[3]-[4] 69

3 II. POWER SYSTEM STABILIZER (PSS) Since voltage regulator control can act to reduce the damping of unit oscillations by sensing terminal voltage, it seem reasonable that a supplementary signal to the voltage regulator can increase damping by sensing some additional measurable quantity. In doing so, not only can the undamping effect of voltage regulator control he cancelled, but damping can be increased so as to allow operation even beyond the steady-state stability limit. This is the basic idea behind the power system stabilizer. The supplementary signal of a PSS may be derived from such quantities as changes in shaft speed (Δω), generator electrical frequency (Δf)), or electrical power (ΔP E ).[3],[15] PSS is designed to work together with generator excitation system in order to produce positive damping torque to ensure system stability in which can be explain by torque vector diagram as Fig.4 below, K1 is synchronizing torque, K1A is synchronizing torque by AVR and K1P is synchronizing torque by PSS. Where D is damping torque DA is damping torque by AVR and DP is damping torque by PSS.[15] Fig.4. AVR + PSS Torque Characteristic Diagram[15] For proper damping action, PSS control settings must he determined, involving the lead, lag, and gain adjustments of the stabilizer. Since the dynamic response of a unit involves both the machine and the external system, such settings may vary from unit to unit. Also, particular PSS settings designed to suppress intertie oscillations may not be effective in damping local machine/system oscillations. Therefore, tuning procedures for PSS generally involve both a field test and a study of the machine and system.[3] Types of Power System Stabilizers PSS Type Block Diagram Brief Description Conventional or Generic Type PSS Dual input CPSS 1.The model consists of a low-pass filter, a general gain, a washout high-pass filter, a phase-compensation system, and an output limiter. 2. The general gain K Determines damping. The washout highpass filter eliminates low frequencies. The phase compensation system is represented by a cascade of two first-order lead-lag transfer functions used to compensate the phase lag between the excitation voltage and the electrical torque of the synchronous machine.[11],[18] The two inputs to dual-input PSS are Δω and ΔPe, with two frequency bands, lower frequency and higher frequency bands, unlike the conventional single input (Δω) PSS. The performance of IEEE type PSS3B is found to be the best one within the periphery of the studied system model. Multiband Power System Stabilizer 1.The multiband power system stabilizer have adjustable working band to control the different mode of oscillation. 2. Three separate bands are used, respectively dedicated to the low-,intermediate-,and high-frequency modes of oscillations 3. The outputs of the three bands are summed and passed through a final limiter producing the stabilizer output Vstab.[11] 70

4 Fuzzy Logic PSS (FLPSS) 1.The fuzzy controller, used in power system stabilizer, normally consists of a two-input and a single-output component. 2.The two inputs are Δω and (Δω), and the output of the FLPSS is a voltage signal, applied to auxiliary control of excitation system.[5] Review of Different PSS Techniques: A. PID Control Approach: PID is used for stabilization in the system. The input is the change in speed from the generator. The aim is to control the angle between load and speed of generator. The PSS parameters are tuned from Open loop transfer function to close loop based on Fuzzy logic. Therefore, the open loop transfer function and maximum peak response parameter make the objective function which is used to adjust PID parameters. B. LAG-LEAD Design: The washout block is used to reduce the over response of the damping during extreme events. Since the PSS produces a component of electrical torque in phase with speed deviation, phase lead blocks circuits can be used to compensate for the lag between the PSS output and the control action(hence lead-lag). It proves its value when the disturbance is multi natured. C. Pole Placement Method: The pole placement method is applied to tune the decentralized output feedback of the PSS. The objective function is selected to ensure the location of real parts and damping ratios of all electro mechanical modes. At the end of the iterative process, all the electromechanical modes will be moved to the region if the objective function converges to zero. D. Model predictive Control: It can handle non linarites and constraints in saturated way for any process model. In these techniques an explicit dynamic model of a plant is used to predict the effect of future actions of manipulated variables on the output. E. Linear Matrix Inequalities: The important feature is the possibility of combining design constraints into a single convex optimization problem.it is used in many engineering related problems. The condition that the pole of a system should lay within this region in the complex plane can be formulated as an LMI constraint. F. Linear Quadratic Regulator: These are well known as compared to lag-lead stabilizers. This is used as a state feedback controller. A coordinated LQR design can be obtained with Heffron- Phillips Model and it can be implemented by using the information available within the power system. During the presence of faults even these methods prove to be stable. G. Genetic Algorithm: Genetic algorithm is independent of complexity of performance parameters and to place the finite bounds on the optimized parameters [8]. As a result it is used to tune multiple controllers in different operating conditions or to enhance the power system stability via PSS and SVC based stabilizer when used independently and through different applications. H. Fuzzy Logic Control: These are rule based controllers. The structure of this logic resembles that of a knowledge based controller; it uses principle of fuzzy set theory in its data interpretation and data logic. It has excellent response with small oscillations. The controller is robust and works effectively under all types of disturbance. It has very short computation time. I. Neural Network: Neural Network is used to approximate the complex non-linear dynamics of power system. Magnitude constraint of the activators is modelled as saturated non-linearity and is used in Lyapnov s stability analysis [9] [10]. The overshoot is nearly same as conventional PSS but settling time is drastically reduced. J. Anfis PSS: The actual design method may be chosen based on real time application and dynamic performance characteristics. If the training data and algorithm are selected properly then good performance can be observed. 1.5 Different Issues with Conventional Controller/Model. [20] Various Facts Controllers for Enhancing Power System Control: Synchronous compensator static (STATCOM) Static var Compensator (SVC) -Checking the voltage Controller of supply flow unified (UPFC) Compensator of convertible series (CSC) Inter-Contrôleur power flow of phase (IPFC) Serial Controller Static synchronous (SSSC) Thyristor controlled series compensator (TEAC)- Check the impedance Thyristor controlled dephasing of the transformer (angle of controls) TCPST Storage of magnetic energy super conduct (SMES)- Control of voltage and power[5]-[6]-[7]-[8]-[9] 71

5 III. RESULTS COMPARISON S. No. Fact s and PSS Combination Result Comparison Simulation 1. The coordinated design of the SVC-based leadlag damping controller and PSS compared to the coordinated design of the SVC-based PID damping controller and PSS. [7] The results of the simulations suggest that transient stability was dramatically improved by the coordinated design of the SVC-based lead-lag damping controller and PSS compared to the coordinated design of the SVC-based PID damping controller and PSS, and to the non coordinated criteria. 2. Swarm intelligence based coordinated controller (PID+PSS) [20] From the literature review many developments have seen in optimization of PSS using various techniques. Many researchers developed advanced control design approaches such as intelligent control, adaptive control and robust control for power system stabilization and oscillation damping. But the existing controllers need more iteration and had computational burden to optimize the parameters for wide range of operating conditions. The proposed PID based PSS controller significantly suppress the oscillations of the rotor speed and power angle. Swarm Intelligence algorithm may use to solve the optimization problem and explore for an optimal set of PID gains and PSS parameters. 3. Coordination between the STATCOM controller and the MB-PSS [8] Solves the problem of power system stabilization by using the advanced static synchronous shunt compensator STATCOM to increase the damping of electromechanical oscillations of the power system and regulates the system voltage by absorbing or generating reactive power to the system. Also, a multiband power system stabilizer MB-PSS is developed to get a moderate phase advance at 72

6 all frequencies of interest in order to compensate for the inherent lag between the field excitation and the electrical torque induced to ensure robust oscillation damping. A combined control of STATCOM with MB- PSS is proposed also in this paper to give more increase of the oscillation damping that improves power system stability. 4. Coordinated control of the SVC and the generic/multiband PSS [11] The multi-machine power system is simulated using MATLAB and the effect of PSS and SVC on dynamic response of the system under single-phase fault and three-phase fault are simulated. It can be concluded that the coordinated control of the SVC and the generic/multi-band PSS is an effective solution to damp low frequency oscillation for multi machine power system. On the other hand, the SVC or PSS alone lacks the ability to damp oscillation under extreme grid disturbances. Hence, for the practical power system, the coordinated control of the SVC and multi-band PSS provides usefull mean to enhance global electromechanical stability. 5 AVR+multiband PSS [13] Multiband PSS is designed to absorb all the disturbances that occur in electrical networks, these disturbances induce electromechanical oscillations in power systems. By equipping this power system with a conventional regulation (AVR + generic PSS) the oscillations are damped gradually and their amplitude is less important. Using Multiband PSS instead of conventional PSS, these power oscillations are damped completely and the power system returns to its stability from the third second, with a modern multiband PSS, get a better response time. 6 MultiBand PSS [18] MB-PSS is better than generic PSS and able to stabilize the grid system in which may damp the disturbances. The MB-PSS signal can modulate the set point of the generator voltage regulator so as to improve damping of the system. The MB-PSS can work on both local area and inter-area of electromechanical oscillations. 73

7 7 Dual input PSS compare to single input PSS [22] The optimal parameters of dual input conventional pss, PSS3B is obtained using pole placement and genetic algorithm technique and are simulated to analyse the dynamic response in both the cases. The technique of computing parameters becomes complex with the increase in number of machines in case of pole placement technique where as the technique of Genetic Algorithm can be used to compute optimal parameters of PSS for wide range of operating conditions in power system and also can be implemented for multi-machine system. The settling time of the PSS is less in case of Genetic Algorithm technique when compared to Pole Placement Technique. 8 PSS + TCSC (Thyristor Controlled Series Compensation ) [21] In this study, a coordination design of TCSC and PSS stabilizers is proposed. The tuning parameters of the proposed stabilizer were optimized using PSO. The proposed stabilizer have been applied and tested on a weakly connected multi machine power system under severe disturbance. The eigenvalues analysis and the nonlinear time domain simulation results show the effectiveness of the proposed stabilizer and its ability to provide good damping of low frequency oscillation and improve greatly the system voltage profile. 9 PID+PSS+TCDB (Proportional integral derivative+ Pss + Thyristor Controlled Dynamic Brake) [9] It can be concluded the PID controller in combination with other controller is effective in the improvement of settling time and ISE. The minimum settling time of has been observed for TCDB. The minimum ISE of has been rendered by PSS-TCDB controller. The TCDB acts only in the acceleration period results in more ISE as compared to PSS with acts in acceleration and retardation period. The controller has been tuned for minimum Integral of Squared Error (ISE) in generator load angle. 74

8 10 FLPSS [19] 11 PSS+UPFC [25] Shown in figure 24 comparison is made between Fuzzy logic based Power System Stabilizer and Convention Power System Stabilizer in terms of Rotor angle v/s Time. From the result it can be conclude that the FLPSS can damp oscillation fast as compare to convention PSS and within 11 second it s make signal completely stable, on the other side PSS take more time to stable the rotor angle of the generator in case of 3 phase to ground fault in the system. PSS can be provided with three input signals, out of which power is given as an input to PSS in the power system considered in the simulation section. Along with operating principle of UPFC, its steady state model is also derived which conveys the power flow control range of UPFC. A power system model is considered which is connected in loop configuration, consist of five buses interconnected through transmission lines (L1, L2, L3) and three phase fault is applied on line L1. The output waveforms indicate that damping time of voltage and power variations is considerably reduced by the introduction of UPFC and PSS into the power system. 12 Fuzzy Logic Power System Stabilizer and Static VAR Compensator [5] The FLPSS is compared with CPSS, with and without presence of SVC. Simulation results indicate that using of FLPSS and SVC together, may improve transient stability of the power system much more in contrast to CPSS and SVC, and also indicate that SVC has a serious effect on transient stability and voltage control. It can be observed, from Fig., that in the case of no SVC, the power system quickly lose its stability after threephase fault clearing. 75

9 13 14 PSS with Fuzzy-PI based TCSC Controller[10] Power system stabilizer (PSS) and Shunt capacitor [27] PSS with Hybrid Fuzzy-PI based TCSC Controller turning is proposed for damping power system oscillations and the effectiveness of the proposed control system is compared with Conventional PI based TCSC Controller and Lead-Lag (LL) based TCSC Controller. To evaluate the usefulness of the proposed Fuzzy-PI controller, it performed the computer simulation for singlemachine infinite bus system. Simulation result shows that Fuzzy-PI controller has a better control performance than PI and LL controllers in terms of settling time and damping effect when the three-phase fault occurs under different loading conditions In this paper modeling and transient stability analysis of the IEEE 9 BUS multi machine system using the electrical Transient analyzer program (ETAP) software has been done to observe the effect of power system stabilizer (PSS) and shunt capacitor. A three phase fault has been created at Bus 7, to analyze the effect of fault and by using the PSS and shunt capacitor to the transient stability improvement has been observed. Transient stability improvement has been tested to three phase fault at bus 7 after 0.1 second and fault has been cleared after 0.3 seconds by use of PSS and shunt capacitor method for the test system the oscillation for generator electrical power has been reduced and steady state power transfer has been enhanced. IV. LITERATURE REVIEW Michel J. Basler, IEEE Task Force on Power System Stabilizers and Prabha Kundur, provides classification of power system stability and fundamentals of the PSS and its effectiveness applied to improve the stability. X. Lei, explained tuning procedure for conventional PSSs in a multi-machine power system based on the non-linear optimization algorithm. Apoorv H Prajapati, Gowrishankar Kasilingam, Radhey Krishna Gopal Ehsan,Afzalan, P. PAVAN KUMAR and Moudud Ahmed explained different types of design(optimization) methods of power system stabilizers and also the concept of power system stability importance. However, swarm intelligence technique and the Adaptive Neuro Fuzzy Inference System (ANFIS) design technique are better compare to the other design techniques proved to be able to overcome the limitations by other methods. K madhuri and Ritesh Ukandrao Chirde studied the interaction between the PSS and UPFC controllers. They found damping time of voltage and power variations is considerably reduced by the introduction of UPFC and PSS into the power system. Seyed Reza Moasheri and Dilip Parmar studied comparison between Fuzzy logic based Power System Stabilizer and Convention Power System Stabilize. Seyed Reza Moasheri combined FLPSS and SVC together and saw fast improvement in transient stability. Rajendraprasad Narne proposed that Fuzzy-PID controller for better damping effect. Ali Darvish FALEHI and Radhey Krishna Gopal gives the combination of 2 leadlag and PID structures as supplementary damping controllers for the SVC and CPSS to enhance the stability of the power system. Lin Xu, Gaber Shabib, Chérif N, Jeremias Leda and Seung-Mook Baek are made a comparative study between conventional PSS and multiband PSS. Multiband PSS 76

10 offers an additional advantage since it produces a signal stabilizing not only from the variation of the angular velocity of the rotor as well as electrical power. Lin Xu combined SVC and multi-band PSS and explained nicely to enhance global electromechanical stability. Divya Prakash and Abhijit N Morab are obtained better response in terms of power swing on implementation of PSS. Khoshnaw Khalid Hama Saleh compared PSS and SVC. He observed that SVC improves damping oscillation and enhance transient stability better than PSS. D. Sabapathia and Dr. R. Anitab, studied and suggested that the combination of AVR, Governor and PSS maintains synchronism during all kinds of faults Neha Maithil, she done Comparative study of PSS and combination of PSS and TCSC controller. Due to effect of TCSC, she obtained improvement in transient performance of SMIB under symmetrical three phase fault. TCSC is most important and best known series controllers which has been employed for many years to enhance power transfer capability of line as well enhance the system stability. Balwinder Singh Surjan, In this paper a comparison of PID, PSS, TCDB controllers is presented through small signal stability of power system comprising of one machine connected to infinite bus and modeled through six K-constants. The power system components such as synchronous machine, exciter, power system stabilizer, PID, TCDB are also modeled after linearization of governing equations. Rampreet Manjhi, in his paper he combined power system stabilizer (PSS) and shunt capacitor for transient stability improvement. He found that oscillation for generator electrical power has been reduced and steady state power transfer has been enhanced. S. I. Barde, In his research he compared D-FACTS technology with FACTS technology. He found that D- FACTS technology provides more reliable approach to enhance power transfer capabilities and transient stability of power system than FACTS technology. He used DSSC with fuzzy logic controller along with PSS as supplementary controller. V. CONCLUSION BASED ON SURVEY If we write the conclusion on above survey, it will be divided in four parts. First part is on fundamentals of PSS and its effectiveness applied to improve the stability, second part is on various design methods of PSS, third part is on combination of various facts devices with various types of PSS and fourth part is on D-Fact technology with PSS. In the second part, Swarm intelligent technique and ANFIS design technique are better. PID control and Genetic algorithm methods may come on second position for design of PSS. In third part authors are used combinations for improvement of transient stability and these are PSS+UPFC, FLPSS+SVC, Lead-lag-PID to SVC+CPSS, MBPSS+SVC, PSS+TCSC, PSS+shunt capacitor. In fourth part used DSSC with fuzzy logic controller along with PSS. All above combinations are used for improvement in transient stability and power transfer capabilities. The combined FLPSS +SVC or PSS+TCSC or MBPSS+SVC or MBPSS+STATCOM together gives fast improvement in T.S. PSS & UPFC reduced damping time of voltage and power variations. T.S. also improved by DSSC with fuzzy logic controller along with PSS. PSS+shunt capacitor reduces the oscillations of generator..mb-pss is better than generic PSS and able to stabilize the grid system in which may damp the disturbances. The MB-PSS signal can modulate the set point of the generator voltage regulator so as to improve damping of the system. The MB-PSS can work on both local area and inter-area of electromechanical oscillations. Hence, for the practical power system, the coordinated control of the SVC and multi-band PSS provides usefull mean to enhance global electromechanical stability. From above combination, FLPSS +SVC & MBPSS+SVC are the best combination for T.S. improvement. But, still we can find the gap and we can use the other combinations like FLPSS+UPFC instead of generic PSS+UPFC or MBPSS and shunt capacitor or MBPSS and UPFC or DFACT technology with PSS with Swarm intelligent technique. VI. REFERENCES [1] X. Lei, Global tuning of power-system stabilizers in multi-machine systems Electric Power Systems Research 58 (2001) [2] IEEE Task Force on Power System Stabilizers, Overview of Power System Stability Concepts IEEE. [3] Prabha Kundur, Definition and Classification of Power System Stability IEEE Transactions On Power Systems 2004 IEEE. [4] Michael J. Basler, Understanding Power-System Stability IEEE Transactions on Industry Applications, Vol. 44, No. 2, March/April [5] Seyed Reza Moasheri, Using Fuzzy Logic Power System Stabilizer and Static VAR Compensator to Improve Power System Transient Stability Conference Paper January 2010 ResearchGate. 77

11 [6] K Madhuri, Modeling and Analysis of Power flow controller in the presence of Power system stabilizer for a Multi-machine system International Journal of Engineering Research & Technology (IJERT) Vol. 1 Issue 6, August ISSN: [7] Ali Darvish Falehi, Optimization and coordination of SVC-based supplementary controllers and PSSs to improve power system stability using a genetic algorithm Turk J Elec Eng & Comp Sci, Vol.20, No.5, [8] Gaber Shabib, Coordinated Design of a Mb-Pss and Statcom Controller to Enhance Power System Stability International Journal of Electrical Engineering and Technology (IJEET), Volume 3, Issue 2, July- September (2012). [9] Balwinder Singh Surjan, Linearized Modeling of Single Machine Infinite Bus Power System and Controllers for Small Signal Stability Investigation and Enhancement International Journal of Advanced Research in Computer Engineering & Technology (IJARCET) Volume 1, Issue 8, October [10] Rajendraprasad Narne, Improving Power System Transient Stability by PSS and Hybrid Fuzzy-PI based TCSC Controllers /12/$ IEEE. [11] Lin Xu, Coordinated Control of SVC and PSS for Transient Stability Enhancement of Multi-Machine Power System TELKOMNIKA, Vol. 11, No. 2, February 2013, pp. 1054~1062. [12] Prof. Aziz Ahmad, System Development to Enhance the Stability of Two Machine Transmission Systems with Static VAR Compensator and Multiband Power System Stabilizer International Journal of Engineering Research & Technology (IJERT) Vol. 2 Issue 9, September [13] Chérif N, The Use of Multiband PSS to Improve Transient Stability of Multimachine Power System International Journal of Power Electronics and Drive System (IJPEDS) Vol.3, No.3, September 2013, pp. 298~303. [14] Ehsan Afzalan, Analysis of the simultaneous coordinated design of STATCOM-based damping stabilizers and PSS in a multi-machine power system using the seeker optimization algorithm Electrical Power and Energy Systems 53 (2013) [15] Seung-Mook Baek, Coordinated Control of PSS and FACTS Devices to Improve Power System Stability Advanced Science and Technology Letters Vol.51 (CES-CUBE 2014), pp [16] Apoorv H Prajapati, Basic Concept of Power System Stabilizer For Power System Stability And Comparison of Different Design Methods International Journal For Technological Research In Engineering Volume 1, Issue 11, July [17] Radhey Krishna Gopal, Transient Stability Analysis of Multi Machine System by PSS Parameter Design using GA International Journal of Engineering Research & Technology (IJERT) Vol. 3 Issue 7, July [18] Jeremias Leda, Analysis of Transient Stability Enhancement Using Multi-Band Stabilizer on South Sulawesi Power Grid International Journal of Engineering Research & Technology (IJERT) Vol. 3 Issue 9, September [19] Dilip Parmar, Performance Analysis of Transient Stability and Its Improvement Using Fuzzy Logic Based Power System Stabilizer 2015 IJEDR Volume 3, Issue 2. [20] Gowrishankar Kasilingam, Coordination of PSS and PID Controller for Power System Stability Enhancement Overview Indian Journal of Science and Technology, Vol 8(2), , January [21] Neha Maithil Transient Stability Enhancement of Single Machine Infinite Bus (SMIB) System using TCSC based Controller Canadian Journal of Basic and Applied Sciences ( CJBAS) Vol. 03(02), 67-77, February [22] P. Pavan Kumar, Dynamic analysis of Single Machine Infinite Bus system using Single input and Dual input PSS Journal of Electrical Engineering. [23] Divya Prakash, Enhancing Stability of Multi- Machine IEEE 9 Bus Power System Network Using PSS International Journal of Advanced Research in Electrical, Electronics and Instrumentation Engineering, Vol. 4, Issue 5, May [24] Abhijit N Morab, Comparative Study of Synchronous Machine, Model 1.0 and Model 1.1 in Transient Stability Studies with and without PSS International Journal of Engineering Research & Technology (IJERT) Vol. 4 Issue 05, May [25] Ritesh Ukandrao Chirde, Enhancement of Power System Stability by using Power System Stabilizer and UPFC International Journal of Engineering Research & Technology (IJERT) Vol. 4 Issue 05, May

12 [26] Khoshnaw Khalid Hama Saleh, Transient Stability Improve ment in Multi-Machine System Using Power System Stabilizer (PSS) and Static Var Compensator (SVC) International Journal of Electrical and Computer Engineering Vol:2, No:12, [27] Rampreet Manjhi, Transient Stability Analysis Of The Ieee 9 Bus Multi Machine System Using The Electrical Transient Analyzer Program (Etap) Software International journal of Electrical and Electronics Engineering (IJEEE), Vol. 5, Issue 3, May 2016,