Abstract KEYWORDS I. INTRODUCTION

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1 Volume 118 No , ISSN: (on-line version) url: ijpam.eu IMPROVING VOLTAGE STABILITY OF POWER SYSTEM USING FACTS DEVICE BY USING PSO TECHNIQUE R.Sreenivasan 1, G.N.Sachin amreiss 2, A. Saranya 3 Department of Electrical and Electronics Engineering, M. Kumarasamy College of Engineering, Karur , India, 1 Corresponding author mail id: sreenivasanr.eee@mkce.ac.in, Abstract an electrical power system network consists of number of buses, individual elements coupled together and to form a big and complex network which has the capable of generation, transmission and distribution of electrical energy over large environmental areas. In order to satisfy the increasing power demand, the power system network is developing each and every day. The power demand is reduced either by install the new generating stations, or by extending the range of the existing loadability limits. As a result, the existing lines are overloaded than ever before and to reducing voltage stability. So instability of voltage is a major issue which attracting worldwide interest because of its result of voltage collapse. In earlier, power system stabilizers (PSS) are used for improving small signal stability. FACTS controllers are currently being incorporated with the power system for dynamic performances. In this project, STATCOM is proposed for improving voltage stability. The IEEE 14 bus system is taken and it is built in MATLAB software. By connecting STATCOM, voltage profile and loadability limits are improved. Optimal location of STATCOM has to be found by PSO algorithm technique. The results are verified through waveforms using MATLAB SOFTWARE. KEYWORDS voltage stability, maximum loading point, STATCOM, particle swarm optimization (PSO), MATLAB simulink. I. INTRODUCTION Power system is a great intricate network, interconnected together that consists of number of buses and generators. Every power system should operate based upon stable operating conditions which includes both stability of angle voltage. The voltage stability is an inevitable factor under normal operating conditions of a power system. The stability of power system is evaluated and the maximum loading point is found and also enhanced the voltage stability. Flexible Alternating Current Transmission Systems is the newest knowledge for provided that reimbursement of reactive power. Various compensators are available like SSC, SVC, TCSC, SSSC etc.this thesis focus on compensator as STATCOM for enhancing the voltage stability and reliability of the power system network. The operation of STATCOM is the reactive power reimbursement where the reactive power and voltage profile of the power system network is improved. It illustrates shunt

2 transformer, voltage source converter, VSC, and capacitors. The STATCOM which is located at a best location in a power system network. And only optimal locations would enhance the upper limit voltage and enlarged loadability limits. II. MATLAB DESCRIPTION MATLAB is a powerful tool for computation of engineering, and applied mathematics. It attempt a powerful programming languages, excellent graphical, and a wide range of expert s knowledge. The main meeting point in MATLAB software is computation by using optional Symbolic Toolbox. All the end results are numerical and inexact. When it becomes to numerical, which is mostly preferred the Maple, Mathematical. MATLAB software is user friendly and very easy to use with standard collections in library. The adverse effect is a low execution speed. Moreover, one can associate with other codes into this software. It is usually not so good choice for maximum-performance of computing process [12]. Even for processor users, MATLAB is a beneficial environment where to search the algorithms in another language also. Most successful computed languages and environments acquired as a distinct nature. MATLAB, have number of essentials, an experimental and graphical bias, results from the interactive environment and it constrict the write-compile-link-execute study cycle, compact and user friendly to the interactive mode, quite than tightly strained. The main element of MATLAB is the Command Window, which is placed in the library. SIMULINK The MATLAB software is the tool which performs the simulation work and the operation cost can be reduced. The operation which can done in the MATLAB is to simulate, designing and we can analyse the circuit and several operations to be performed under the specific function. To perform the variable and non-variable functions and like linear and non linear systems the library toolbox can be used. The design approach can be performed in both the top down and the bottom down will be done by this model. In the MATLAB the most important one is the simulink, the process is simple in which the back and front operation can be performed easily, it is an user friendly by improving the features. III.FACTS DEVICE To improve the controllability and wide transmission system the FACTS devices can be used. And it defined as one of power electronic based system which controls the many transmission systems. Flexible Alternating Current Transmission System (FACTS) devices is developed mainly based on the tools of power electronics is to strengthen the quality of transmission and generation system. FACTS devices are divided into two types. The first type is the thyristors based control in which it controls the reactor by using the switches. The second type of the FACTS devices is to control the power flow of the system by using the advanced control technique and by power electronic switches. By the switching technology it can be classified into three types they are, first is phase shifting transformer is also known as mechanically switched, and by using the IGBT switching and the fast switching can be done. The FACTS can be further classified into static VAR compensator and the phase shifting transformer (PST) in these techniques are mostly used in power system, the range of the FACTS device can be changed by implementing the new techniques in power electronics. The controllers based on the power electronics is mainly focused on FACTS devices and the stability of transmission system can be improved by the FACTS devices of the controlling techniques. [8][2]. In recent trends the FACTS device application are more, the important factor like the power flow, phase angle and the magnitude of the distribution side and the transmission side to be more controllable and it

3 should be more flexible. The new FACTS applications are from the renewable energy sources and the world wide power flow by increasing the needs. STATCOM Now a days the increasing the power demands and the requirement is increasing day by day and its need in a quality manner and in the consumable cost is the major problem in the generation transmission and the distribution system. The developing countries are making the stabilization techniques and the voltage regulation for the efficient and in order to make use properly in the transmission process. The power electronics switches are mainly used for the protecting and in the types of SSSC, STATCOM and UPFC are designed properly and its self-regulating for the particular appliance. The reactive power controlling is the main purpose of the STATCOM. The process of STATCOM is to observe and distribute the voltage and current in the form of wave forms by desired outcomes of reactive power. The block diagram of STATCOM is shown in Fig 1.1. Fig 1 Concept of STATCOM device The coupling transformer is used to connect the VSC to the bus. The terminal which I have given in these proposed system is Vac, Iac, Vout, Vdc, Idc. In that the notation are bus vaoltage, STATCOM injected current. The DC voltage and current can be taken from the capacitor side. The positive side and the negative side can be defined as the power electronic switch IGBT with the back to back diodes and the top three switches are the positive group and the bottom three are the negative group. When the diode is conduct or its operated the converter operation is take place and the inverter operation also be take place. CRITERIA FOR PLACEMENT OF STATCOM The criteria for choosing the optimal location for STATCOM based on PSO algorithm can be explained as below STATCOM should be located at load (PQ) bus which has the lowest voltage in the power system network [9]. Slack and generator buses are renouncing. Since the setting parameters of the FACTS device should be restricted to the parameters of non-load bus. In addition to that, placing the device in these two buses would produce unpredicted results in the power flow solution [9]. Power System Constraints The transmission systems are depends on the stability and thermal limits while, focus on the feature of power deliver is superior to ever[3]. The limitations of the transmission system are in many forms and may engage power transfer involving two areas or within a single area or region and may include one or more of the following characteristics: Steady-State Power Transfer Limit

4 Dynamic voltage limit Voltage Stability Limit Inadvertent Loop Flow Limit IV. PARTICLE SWARM OPTIMIZATION TECHNIQUE There are many evolutionary methods are there in which we found the optimal location of STATCOM using Particle swarm optimization (PSO). PSO adaptation is an optimization model that simulates the ability of human societies to process knowledge [1]. The PSO is efficient global optimizers for solving the continuous variable problems. The algorithm is relevant to cognition; in particular the schematic knowledge is represented by neural networks. Particle swarm optimization is successfully optimized the network weights, and also simulating the adaptive sharing among social collaborators. Particle swarm optimization has roots in two main component methodologies. In general, this method uses the bird flocking, fish schooling, and swarming theory in particular. It is also related to evolutionary computation, and it ties with both genetic algorithms and evolutionary programming [1][6] P k i best remembered individual particle p P k g - best remembered swarm position c1, c2 cognitive and social parameters r1, r2 random numbers between 0 and 1 Position of individual particles updated as follows X i k+1 = X i k + V i k+1 (1) With the velocity calculated as follows V i k+1 = V i k + c1 r1 (P i k - X i k) + c2 r2 (P g k X i k) (2) A. IMPLEMENTATION OF PSO ALGORITHMS STEP 1: Initialization STEP2: Calculation of fitness function STEP3: The inertia weight and acceleration coefficients are taken. STEP4: New velocity and location for each particle is Calculated using (1) and (2) STEP5: The iteration need to reach global minimum of fitness value (computation speed) and best fitness value. Advantages of PSO algorithm: (1)PSO is based on the intellect. It can be useful for both engineering use and scientific research [7]

5 (2)PSO have no overlapping and alteration calculation. The search can be depends upon the speed of the movement of the particle. (3)The estimation of PSO is very simple. When compared with other developing calculations, it occupies the larger optimization capacity and it can be finished easily. (4) PSO adopts the valid integer system, and it is decided directly by the solution. The number of the factor is equal to the constant of the solution. V. IEEE 14 BUS SYSTEM In this project IEEE 14 bus system is taken as the test system and it is built in MATLAB software. Load data, bus data and generator data are taken and it is drawn by means of MATLAB. CASE 1: IEEE 14 bus system was drawn by using MATLAB software and to find the low voltage bus in the 14 bus system using PSO algorithm. CASE 2: Considering the STATCOM connected to the low voltage bus and to improve the voltage stability. We have the standard IEEE 14 bus data in which the bus system has 3 Slack bus, PV buses and PV buses Inorder to compensate the voltage sag,statcom is a power electronic device that is used to inject 3-phase voltage and in synchronism with the distribution feeder voltages. The solution for the voltage sag problem is STATIC COMPENSATOR because it is quickest, flexible and more accurate one. The power electronic switches like the STATCOM it can provides the controllable three phase supply voltage sources, in which it can add with the vector voltage i.e. phase angle and the frequency when the sag occurs, in the before sag condition is used to store the load voltage [4]. The power electronic switch is mainly designed for the protecting and ensuring the whole process for the particular output with the particular load. The STATCOM it can take the very micro seconds to restore the voltage in the load side. Nowadays the so many proposed methods and the controlling techniques have been implemented for the STATCOM. In The proposed paper, it describes the clear idea about the STATCOM, its performance, operation, principles and the compensating technique and the controlling techniques can be recall with the limitation and the process [5]. The power circuit and control systems are designed using the simulation software and using the system block elements. The network source is three-phase AC source. The AC loads i.e. three phase supply is linked with the load at the end process. STATCOM is linked as parallel and it illustrate the PWM voltage source inverter circuit and a DC capacitor associated at DC bus. Snubber circuits are used for protection and is always with the IGBT switch are parallel connected. The Simulation is mainly for the variable and non variable loads by the STATCOM system. In the system the constant load is designed using the block three-phase parallel R-L load. In the system the R and the R-C circuits are connected with the output of power electronic components is the designing process. The sudden load can be added and it is removed by connecting thee load with the parallel manner. In the designing process from the sources to the load the feeder is connected in between them, by using the suitable values and it designed by the inductive and the resistive elements. Control algorithm of STATCOM with PI controllers. Two PI controllers are used in the system. First PI controller regulates the DC link voltage while the second PI controller regulates the terminal voltage at PCC. For STATCOM reference currents, the

6 in-phase components are dependable for power correction of load and for supply reference currents the quadrature components are to regulate the AC system voltage at PCC. By using the load data and bus data we calculate the voltage at each bus by Newton Raphson load flow method. In case 1 the voltage profile is very low on some buses and there is a lack of voltage stability. But in case 2, loadability limits and the voltage profile is improved since STATCOM is connected on low voltage bus (bus 10). VI RESULTS AND DISCUSSIONS A. POWER FLOW RESULT IEEE 14 Bus system Case 1: The IEEE-14 bus system and PSO analysis is performed without connecting STATCOM Case 2: A similar analysis can be carried on the same bus system but considering the STATCOM connected to the low voltage. Both the results are found and the table 4.1 and 4.2 shows the results of voltage profile of each bus with STATCOM and without Statcom respectively. BUS V(Per.Unit) REALPOWER FLOW (Per.Unit) Table 4.1 voltage profile of each bus without STATCOM In case 2 STATCOM is connected and hence the voltage profile is get improved. The power flow results for case 2 are given in the table. Power flow results for IEEE-14 bus system (with STATCOM)

7 BUS VOLTAGEV(P.U) REALPOWER FLOW (P.U) Table 4.2 voltage profile of each bus with STATCOM In table 4.2, voltage profile is very low on bus 5, 9, 10, 11 when the load is increased in the IEEE 14 bus system. When STATCOM is connected to bus 10, voltage profile is improved in bus 5, 9, 10, 11. On comparing the above two cases, voltage profile is increased in the case 2 since STATCOM is connected. B. WAVE FORM FOR IEEE 14 BUS SYSTEMS CASE 1: Without STATCOM CASE 2: With STATCOM Figure 4.1 Waveform for voltage profile of each bus without STATCOM Figure 4.2 Waveform for voltage profile of each bus with STATCOM

8 VII CONCLUSION This project describes the influence of STATCOM on the power system voltage stability and improvement of loadability improvement. The STATCOM are able to participate in the power system inter area oscillation damping by changing the compensated reactance or to provide reactive power, when supplementary control strategies is adopted. The IEEE 14 buses are taken as test system is built in Matlab Simulink software and to increase the load in the particular load bus. To find the optimal location of STATCOM by using PSO algorithm, then the STATCOM is connected to the low voltage bus for enhancing the voltage profile and increasing the loadability limits. It can be concluded that STATCOM is the better solution in terms of improving voltage profile and small signal stability when the load is increased in IEEE system. REFERENCES [1] Seraj ahamad, 1m.tech-power system, department of electrical & electronics engg.al-falah school of engineering & technology, prof. Aziz ahmed, 2department of electrical & electronics engg., al-falah school of engineering & technology. Prof. M.a khan, 4assistant professor, department of electrical engineering., greater noida institute of technology. optimal location of statcom using pso in ieee 30 bus system, ijarse transactions, vol. No.2, issue no.5, may 2013 [2] Sujitha G.V.N, Student, JNTU College of Engineering, Pulivendula, India B.Narasimha Reddy, Adhoc lecturer, JNTU College of Engineering, Pulivendula, India, Improving the loadability of the wind integrated power system using STATCOM placed at an optimal location IEEE transactions,vol. 3, issue 1, january [3] Rajnikant H. Bhesdadiya, PhD Scholar,School of Engineering, RK University, Rajkot, India, Assistant Professor, L.E. College, Morbi.Dr. Rajesh M. Patel,Principal, HJD Institute of Technical Education and Research, Kera, Kutchh, Member, IEEE, ISTE. Available transfer capability calculation Methods: a review IJAREEIE, Vol. 3, Issue 1, January 2014 [4] Sarika Varshney,IEEE student member, Laxmi Srivastava, IEEE student member, Manjaree Pandit, IEEE student member, Madhav Institute of Technology, Gwalior, India. Comparison of PSO Models for Optimal Placement and Sizing of Statcom international journal of engineering rearch and applications issn: , vol. 4, issue 3(version 1),march 2014,pp [5] Hiroshi Yonezawa, Toshiaki Shimato The Kansai Electric Power Co., Inc, Osaka, Japan, Michiharu Tsukada, Katsuhiko Matsuno, Isao Iyoda (Member), Mitsubishi Electric Corporation, Kobe, Japan, Study of a STATCOM Application for Voltage Stability Evaluated by Dynamic PV Curves and Time Simulations IEEE transactions,vol.2, No 4, july 2013 [6] James Kennedy and Russell Eberhart, Particle Swarm Optimization, IEEE [7] Y. N. Yu, Particle Swarm Optimization, Electric Power System Dynamics. Academic Press, [8] Alok Kumar Mohanty, Amar Kumar Barik, Power System Stability Improvement Using FACTS Devices (IJMER)

9 [9] Sundararaju, A Nirmal Kumar, S Jeeva, A Nandhakumar, Performance Analysis And Location Identification of STATCOM On IEEE-14 Bus System Using Power Flow Analysis, Journal Journal of Theoretical & Applied Information Technology, 60(2), , [10] R.Karthikeyan, Comparison and Performance Analysis of FACTs Controller in System Stability, Circuits and Systems (CS) Volume 7, September 2016, pp ISSN: [11] K. Sundararaju, A. Nirmalkumar, February 2012, Cascaded Control of Multilevel Converter based STATCOM for Power System Compensation of Load Variation, International Journal of Computer Applications,Vol.40,No.5,PP [12] Uma,J,Jeevanandham,A,2015, Performance of Four phase Switched Reluctance Motor Drive using Single Pulse Width Modulation Technique under constant turn off angle and random turn off angle, ARPN Journal of Engineering and Applied Sciences, VOL. 10, NO. 5, pp

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