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- 1. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 4, July-August (2013), © IAEME 232 POWER FLOW SOLUTION WITH FLEXIBLE AC TRANSMISSION SYSTEM DEVICES Guguloth Ramesh1 and T. K. Sunil Kumar2 1 Guguloth Ramesh, Research Scholar is with EED, the National Institute of Technology Calicut, Kerala-673601, and INDIA 2 Dr.T.K. Sunil Kumar.Assistant Professor is with EED, the National Institute of Technology Calicut, Kerala-673601, and INDIA ABSTRACT Power flow analysis is the backbone of power system analysis and design. It is necessary for planning, operation, economic scheduling and exchange of power between utilities. This paper proposes load flow solution under steady state condition with flexible AC transmission system (FACTS) devices. FACTS technology opens up new opportunity for operation and control of power system. Out of the various FACTS devices Thyristor Controlled Series Capacitor (TCSC) and Unified Power Flow Controller (UPFC) are the right choices for the maximization of power flow in power system, which has been selected to control power flow in the transmission lines. TCSC is used to minimize active power losses and UPFC is minimizing both real and reactive power losses in the system. Test bus system is modeled and simulated using MATLAB (Power System Analysis Toolbox). Keywords: Load Flow Analysis, FACTS, TCSC and UPFC. NOMENCLATURE FACTS Flexible AC Transmission Systems TCSC Thyristor Control Series Capacitors UPFC Unified Power Flow Controller ܲ Real Power Flow from ݅௧ Bus to ݆௧ Bus ܳ Reactive Power Flow from ݅௧ to ݆௧ Bus ܸ , ܸ Voltage Magnitudes at ݅௧ and ݆௧ Bus ߜ , ߜ Angles of voltage at ݅௧ and ݆௧ Bus ܤ , ܩ Suceptance and Conductance of the lines ܲ Real Power Flow from ݆௧ to ݅௧ Bus INTERNATIONAL JOURNAL OF ELECTRICAL ENGINEERING & TECHNOLOGY (IJEET) ISSN 0976 – 6545(Print) ISSN 0976 – 6553(Online) Volume 4, Issue 4, July-August (2013), pp. 232-244 © IAEME: www.iaeme.com/ijeet.asp Journal Impact Factor (2013): 5.5028 (Calculated by GISI) www.jifactor.com IJEET © I A E M E
- 2. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 4, July-August (2013), © IAEME 233 ܳ Reactive Power Flow from ݆௧ to ݅௧ Bus R Total Resistance in the Transmission Line ܺ, ܺ Line Reactance and Capacitance ܺ௦, ܺ௦ Series and Shunt Sides Line Reactance ܫ Transmission Line Current ܸூ ഥ Voltage Due to Series Compensation ܲ, ܳ Real and Reactive Power Losses ்ܺௌ Reactance of TCSC ܺ Capacitive Reactance I. INTRODUCTION Load flow solution is a solution of the power system network under steady state condition subject to certain inequality constraints under which system operates. The load flow solution gives the nodal voltages and phase angles and hence the power injection at all the buses and power flows through interconnecting power transmission lines [1]. Load flow solution is essential for designing a new power system and for planning extension of the existing one for increased load demand. These analyses require the calculation of numerous load flows under both normal and abnormal operating conditions. IEEE 14 bus system is modeled in deregulated environment. Conventional techniques for solving the load flow problem are iterative method using the Newton-Raphson method [2]-[3]. An opening of unused potentials of transmission system due to environmental, right-of-way and cost problems is a major concern of power transmission network expansion planners and policy makers. Flexible AC Transmission Systems (FACTS) controllers can be helpful in utilizing the maximum capacity of the transmission network to their limits without threatening the stability and security of the network. FACTS controllers [4] provide new control facilities, both in steady state power flow control and dynamic stability control. The possibility of controlling power flow in an electric power system without generation rescheduling or topological changes can improve the performance considerably [5]. The TCSC and UPFC, the most versatile devices have been selected to minimize losses in transmission lines [6]-[7]. TCSC allows rapid and continuous changes of the transmission line impedance. Active power flows along the compensated transmission line can be maintained at a specified value under a range of operating conditions. In load flow studies the TCSC can be represented in several forms. For instance, the model presented in [8]-[9] is based on the concept of a variable Series Compensator whose changing reactance adjusts it in order to constrain the power flow across the branch to a specified value. The reactance value is determined efficiently by means of Newton's method [10]. Among FACTS devices, the unified power flow controller (UPFC) is emerging as a promising solution for improving power system characteristics for its high degree of controllability of many power system variables [11]. UPFC can be used for power flow control, loop-flow control, load sharing among parallel corridors, enhancement of transient stability, mitigation of system oscillation, voltage regulation and reduced losses in the system [12]-[13].This analysis is based on comparison of the results in every line before and after installation of UPFC in a test system [14]-[15]. Present paper IEEE 14 bus ill condition system is modeled, the limit violation in the transmission lines are predicted with power flow solution and remedial action is taken by FACTS devices. This paper is organized as follows: Section II deals with load flow solution. Section III presents Thyristor Controlled Series Capacitor (TCSC). Section IV describes Unified Power Flow Controller (UPFC). Section V presents simulations results at various operating conditions. Section VI concludes the paper.
- 3. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issu II. LOAD FLOW SOLUTION The power flow solution is an importan system. Unlike traditional circuit analysis, a power flow study usually uses simplified notation such as a one-line diagram and per-unit system, and focuses real and apparent) rather than voltage and current. The advantage in studying power flow analysis is in planning the future expansion of power systems as well as in determining the best operation of existing systems. Fig.1 shows line diagram of IEEE 14 bus system, which is modeled in MATLAB power system analysis toolbox. Power flow analysis is being used for solving power flow problem by Newton-Raphson method. Information obtaine voltage at each bus, real and reactive II.1 Newton-Raphson Method The Newton-Raphson method is widely used for solving non the original non-linear problem into a sequence of linear problems whose solutions approach the solutions of the original problem. Let G=F(x, y) be an equation where the variables is a specified quantity. If F is non-linear in nature there may not be a direct solution to get the values of x and y for a particular value of iteratively solve for the real values of calculated value of F (using the estimates of x and y) i.e procedure is as follows: let the initial estimate of International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 6553(Online) Volume 4, Issue 4, July-August (2013), © IAEME 234 The power flow solution is an important tool involving numerical analysis applied to a power system. Unlike traditional circuit analysis, a power flow study usually uses simplified notation such unit system, and focuses on various form of AC power (i.e. real and apparent) rather than voltage and current. The advantage in studying power flow analysis is in planning the future expansion of power systems as well as in determining the best operation of Fig.1 IEEE 14 bus system diagram of IEEE 14 bus system, which is modeled in MATLAB power Power flow analysis is being used for solving power flow problem by Raphson method. Information obtained from load flow problem is magnitude and angle of voltage at each bus, real and reactive power at each line and each bus, and losses in the system. Raphson method is widely used for solving non-linear equations. It linear problem into a sequence of linear problems whose solutions approach the be an equation where the variables x and y are the arguments of linear in nature there may not be a direct solution to get the values for a particular value of G. In such cases, we take an initial estimate of iteratively solve for the real values of x and y until the difference is the specified value of (using the estimates of x and y) i.e. ∆F is less than a tolerance value. The let the initial estimate of x and y is and respectively, International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – August (2013), © IAEME tool involving numerical analysis applied to a power system. Unlike traditional circuit analysis, a power flow study usually uses simplified notation such various form of AC power (i.e. reactive, real and apparent) rather than voltage and current. The advantage in studying power flow analysis is in planning the future expansion of power systems as well as in determining the best operation of diagram of IEEE 14 bus system, which is modeled in MATLAB power Power flow analysis is being used for solving power flow problem by d from load flow problem is magnitude and angle of power at each line and each bus, and losses in the system. linear equations. It transforms linear problem into a sequence of linear problems whose solutions approach the are the arguments of function F. G linear in nature there may not be a direct solution to get the values n such cases, we take an initial estimate of x and y and is the specified value of G and the is less than a tolerance value. The
- 4. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 4, July-August (2013), © IAEME 235 Using Taylor series, ܩ ൌ ܨሺݔ , ݕሻ ቚ డி డ௫ ቚ ௫బ,௬బ . ∆ݔ ቚ డி డ௬ ቚ ௫బ,௬బ . ∆ݕ (1) where డி డ௫ and డி డ௬ are calculated at x , y ܩ െ ܨሺݔ , ݕሻ ൌ ∆ܨ ൌ డி డ௫ . ∆ݔ డி డ௬ . ∆ݕ (2) In the matrix form it can be written as ∆ܨ ൌ ቀ డி డ௫ డி డ௬ ቁ ቀ∆௫ ∆௬ ቁ (3) or ቀ∆௫ ∆௬ ቁ ൌ ݅݊ݒ ቆቀ డி డ௫ డி డ௬ ቁቇ ሺ∆ܨሻ (4) After the first iteration x is updated to ݔଵ = ݔ + ∆ݔ and y to ݕଵ = ݕ + ∆ݕ. The procedure is continued till after some iteration both ∆F is less than some tolerance value ε. The values of x and y after the final update at the last iteration is considered as the solution of the function F. For the load flow solution, the non-linear equations are given by equation (3). There will be 2n – 2 – p such equations, with n being the total number of buses and p the number of PV and generator buses. ቀ∆ ∆ொ ቁ ൌ ቆ ങು ങഃ ങು ങ|ೇ| ങೂ ങഃ ങೂ ങ|ೇ| ቇ ቀ ∆ఋ ∆|| ቁ (5) or ቀ ∆ఋ ∆|| ቁ ൌ ݅݊ݒ ቆ ങು ങഃ ങು ങ|ೇ| ങೂ ങഃ ങೂ ങ|ೇ| ቇ ቀ∆ ∆ொ ቁ (6) The matrix of equation (6) consisting of the partial differentials, is known as the Jacobian matrix and is very often denoted as J.∆P is the difference between the specific value of P (ܲௌ ) and the calculated value of P using the estimates of δ and |V| in a previous iteration. We calculate ∆Q similarly. The Newton power flow is the most robust power flow algorithm used in practice. However, one drawback to its use is the fact that the terms in the Jacobian matrix must be recalculated each iteration, and then the entire set of linear equations in equation (6) must also be resolved each iteration. Since thousands of complete power flow are often run for planning or operations study, ways to speed up this process were devised. III. THYRISTOR CONTROLLED SERIES CAPACITORS It is basically variable impedance, such as capacitor or inductor etc. Series controller injects voltage in series with the line. As long as the voltage is in phase quadrature with line current, the
- 5. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 4, July-August (2013), © IAEME 236 series controller only supplies or absorb variable reactive power. The value of reactance of TCSC ( ்ܺௌ) is function of the reactance of the line,ܺ where the device is located. Fig.2 Equivalent circuit of TCSC The real and reactive power flow from bus i to bus j can be expressed as ܲ ൌ ܸ ଶ ܩ – ܸܸܩ cos൫ߜ െ ߜ൯ െ ܸܸܤ sin൫ߜ െ ߜ൯ (7) ܳ ൌ ܸ ଶ ൫ܤ െ ܤ௦൯ െ ܸܸܩ sin൫ߜ െ ߜ൯ ܸܸܤ cos ൫ߜ െ ߜ൯ (8) Similarly, the real and reactive power flow from bus j to bus i can be expressed as ܲ ൌ ܸ ଶ ܩ – ܸܸܩ cos൫ߜ െ ߜ൯ ܸܤ sin൫ߜ െ ߜ൯ (9) ܳ ൌ െ ܸ ଶ ൫ܤ െ ܤ௦൯ ܸܸܩ sin൫ߜ െ ߜ൯ ܸܸܤ cos ൫ߜ െ ߜ൯ (10) The active and reactive power loss on each line k can be formulated as ܲ ൌ ܲ ܲ ൌ ܸ ଶ ܩ ܸ ଶ ܩ െ 2ܸܸܤ cos ൫ߜ െ ߜ൯ (11) ܳ ൌ ܳ ܳ ൌ െ ܸ ଶ ൫ܤ െ ܤ௦൯ െ ܸ ଶ ൫ܤ െ ܤ௦൯ 2ܸܸ cos ൫ߜ െ ߜ൯ (12) Fig.2 shows a model of transmission line with TCSC connected between buses i and j. The transmission line is represented by its lumped π-equivalent parameters connected between the two buses. During steady state operation, the TCSC can be considered as a static reactanceെ݆ܺ. The controllable reactance ܺ is directly used as the control variable in the power flow equations. IV. UNIFIED POWER FLOW CONTROLLER
- 6. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 4, July-August (2013), © IAEME 237 A unified power flow controller (UPFC), which has the capabilities of voltage regulation, series compensation, and phase shifting, is one of the most versatile FACTS controllers. Fig.3 the UPFC model in PSAT It can independently and very rapidly control both real and reactive power flows in a transmission line. This paper focuses on the representation of UPFCs in power flow computations. It gives a novel approach to include such devices in power flow studies. The UPFC model in PSAT is shown in Figure .3, according to this figure, there are some parameters that can be adjusted for keeping voltage level and power flow of the network. The related formulae are described below: the real and reactive power flow from ݅௧ Bus to ݆௧ Bus ܲ ൌ ܲ௦ ܴ݁ ൛ܸܫ തതതതതതכ ൟ (13) ܳ ൌ ܳ௦ ݉ܫ ൛ܸܫ തതതതതതכ ൟ Similarly the real and reactive power flow from ݆௧ Bus to ݅௧ Bus ܲ ൌ െ ܴ݁ ൛ܸܫ തതതതതതכ ൟ (14) ܳ ൌ െ ݉ܫ ൛ܸܫ തതതതതതכ ൟ The real and reactive power ܲ௦and ܳ௦absorbed by the shunt side are: ܲ௦ ൌ ܸܩ௦ െ ݇௦ܸௗܸܩ௦ܿݏሺݒെ ןሻ െ ݇௦ܸௗܸܤ௦ ݊݅ݏሺݒെ ןሻ (15) ܳ௦ ൌ െܸ ଶ ܤ௦ ݇௦ܸௗܸܤ௦ܿݏሺݒെ ןሻ െ ݇௦ܸௗܸܩ௦ ݊݅ݏሺݒെ ןሻ (16) and the current ܫ തതതand the voltage ܸതdue to seriescompensations: ܫ തതത ൌ ሺଵିభതതതതሻ൫ഢഥିണഥ ൯ିమതതതതതതത ோାಽ (17)
- 7. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 4, July-August (2013), © IAEME 238 ܸത ൌ ܽଵതതത൫ܸప ഥ െ ܸఫ ഥ൯ ܽଶതതതܸூ ഥ (18) Where ܸூ ഥ ൌ ݇௦ܸௗ݁ఉ (19) ܽଵതതത ൌ െ ோೞାೞ ሺோି ோೞሻାሺಽି ೞሻ (20) ܽଶതതത ൌ െ ோೞାೞ ሺோି ோೞሻାሺಽି ೞሻ (21) According to above equations, this model of UPFC is applied to a transmission line in the system to obtain the different results with and without UPFC, and the results are analyzed. V. SIMULATION RESULTS The load flow solution for IEEE 14 bus system has been modeled in MATLAB power system analysis tool box. All the results are analyzed under ill condition system, and with FACTS devices. Fig.4 IEEE 14 Bus system is modeled in MATLAB (PSAT) Figure.4 shows the modeled IEEE 14 bus system, which contained 5 generators, 11 loads, 4 transformers, 20 transmission lines, operating at 50 Hz frequency and base is 100 MVA. The power flow solution after the simulation is given in the Table I. The real and reactive power generation and demand at each bus, total real and reactive power losses in the system are obtained.
- 8. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 4, July-August (2013), © IAEME 239 TABLE I Normal case Bus No P (MW) Gen P (MW) Load Q (MVAR) Gen Q (MVAR) Load 1 352.16 0 -27.5115 0 2 40 30.38 96.484 17.78 3 0 131.88 60.6285 26.6 4 0 66.92 0 5.6 5 0 10.64 0 2.24 6 0 15.68 46.1577 10.5 7 0 0 0 0 8 0 0 30.0037 0 9 0 41.3 0 23.24 10 0 12.6 0 8.12 11 0 4.9 0 2.52 12 0 8.54 0 2.24 13 0 18.9 0 8.12 14 0 20.86 0 7 Total 392.16 362.60 205.76 113.98 Loss = 29.56[MW] = 91.80[MVAR] (a) (b) (C) Fig.5 Voltage magnitude in p. u(a), Real power profile in MW (b), Reactive power profile in MVAR(c)at each bus
- 9. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 4, July-August (2013), © IAEME 240 The total real power demand is 362.60 (MW) against real power generation in system is 392.16 (MW) and real power loss is 29.56 (MW). The total reactive power demand is 113.98 (MVAR) against total reactive power generation in system is 205.76 (MVAR) and reactive power loss is 91.80 (MVAR). In this system the active and reactive power limits violation in line 11 (connected between buses 1-2) and line 14 (connected between buses 1-5) are observed, which have been selected to connect the FACTS devices in the system. To minimize limit violation as well as losses in the system, the FACTS (TCSC, UPFC) are used, which help the transmission line to maintain within the limits, minimize losses, and increase transmission line transfer capabilities. The results of system without and with FACTS devices are analyzed in the subsections. V.1 IEEE 14 system with TCSC Table II, shows results of line flows with TCSC connected in the system. TABLE II Line flows Line Without TCSC TCSC b/w Bus 1-2 TCSC b/w Bus 1-5 From Bus To Bus P Loss MW Q Loss MVA R P Loss MW Q Loss MVA R P Loss MW Q Loss MVA R 0 2 05 1 1.82 2.00 2.01 2.58 1.51 1.00 06 12 2 0.17 0.35 0.17 0.35 0.16 0.35 12 13 3 0.02 0.02 0.02 0.02 0.02 0.02 06 13 4 0.55 1.09 0.55 1.09 0.55 1.08 06 11 5 0.31 0.66 0.31 0.66 0.30 0.63 11 10 6 0.14 0.33 0.14 0.33 0.13 0.30 09 10 7 0.00 0.01 0.00 0.01 0.00 0.00 09 14 8 0.13 0.28 0.13 0.28 0.13 0.28 14 13 9 0.27 0.56 0.27 0.56 0.26 0.54 07 09 10 0.00 2.61 0 2.62 0 2.61 01 02 11 10.2 25.5 0 27.7 9.31 22.5 03 02 12 4.73 15.3 4.83 15.7 4.53 14.4 03 04 13 0.97 -0.9 0.91 -1.1 0.97 -1.0 01 05 14 5.96 19.3 5.23 16.3 0 25.7 05 04 15 0.89 1.53 0.82 1.31 0.97 1.76 02 04 16 3.25 5.97 3.44 6.55 2.93 4.97 04 09 17 0 0.57 0.00 0.58 0.00 0.59 05 06 18 0 10.6 0 10.5 0 10.6 04 07 19 0 4.15 0 4.17 0 4.09 08 07 20 0 1.68 0 1.68 0 1.48 Total Losses 29.5 91.8 18.9 92.1 21.8 92.2
- 10. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 4, July-August (2013), © IAEME 241 Without TCSC the losses in the system is 29.5 (MW) and 91.8 (MVAR). With TCSC connected in the line 11 (between buses 1-2) the real power loss reduced from 29.5 to 18.9 (MW) and the reactive power loss approximately remains same, when the TCSC connected in the line 14 (between buses 1-5) the real power loss reduced from 29.5 to 21.8 (MW) and the reactive power loss approximately remains same. The location of TCSC as in line 11 gives more advantage than as in line 14. TCSC can minimize only real power not reactive power losses, and limit violation in the system. V.2 IEEE 14 system with UPFC Table III, shows results of line flows with UPFC connected in the system. Without UPFC the losses in the system is 29.5 (MW) and 91.8 (MVAR). With UPFC connected in the line 11 (between buses 1-2), the real power loss reduced from 29.5 to 18.6 (MW) and the reactive power loss from 91.8 to 87.5 (MVAR).When the UPFC connected in the line 14 (between buses 1-5) the real power loss reduced from 29.5 to 20.0 (MW) and the reactive power loss from 91.8 to 86.9 (MVAR). The location of UPFC as in line 11 gives more advantage than in line 14. UPFC can minimize both real power and reactive power losses, and limit violation in the system. TABLE III Line flows Line Without UPFC UPFC b/w Buses 1-2 UPFC b/w Buses 1-5 From Bus To Bus P Loss MW Q Loss MV AR P Loss MW Q Loss MVA R P Loss MW Q Loss MVA R 0 2 05 1 1.82 2.00 2.17 3.08 1.19 0.02 06 12 2 0.17 0.35 0.17 0.35 0.16 0.35 12 13 3 0.02 0.02 0.02 0.02 0.02 0.02 06 13 4 0.55 1.09 0.55 1.09 0.55 1.08 06 11 5 0.31 0.66 0.31 0.65 0.30 0.63 11 10 6 0.14 0.33 0.14 0.32 0.13 0.30 09 10 7 0.00 0.01 0.00 0.01 0.00 0.00 09 14 8 0.13 0.28 0.13 0.28 0.13 0.27 14 13 9 0.27 0.56 0.27 0.56 0.26 0.54 07 09 10 0.0 2.61 0 2.62 0 2.60 01 02 11 10.2 25.5 0 24.3 8.21 19.2 03 02 12 4.73 15.3 4.92 16.1 4.32 13.6 03 04 13 0.97 -0.9 0.87 -1.2 1.06 -0.8 01 05 14 5.96 19.3 4.68 14.1 0 26.1 05 04 15 0.89 1.53 0.76 1.39 1.06 2.18 02 04 16 3.25 5.97 3.60 7.04 2.58 3.92 04 09 17 0.00 0.57 0.00 0.58 0.00 0.59 05 06 18 0 10.6 0 10.5 0 10.7 04 07 19 0 4.15 0 4.19 0 4.04 08 07 20 0 1.68 0 1.68 0 1.43 Total Losses 29.5 91.8 18.6 87.5 20.0 86.9
- 11. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 4, July-August (2013), © IAEME 242 V.3 Compression between TCSC and UPFC TABLE IV Buses B/W 1-2 (Line 11) Buses B/W 1-5 (Line 14) P Loss (MW) Q Loss (MVAR) P Loss (MW) Q Loss (MVAR) TCSC 18.90 92.19 21.82 92.22 UPFC 18.66 87.50 20.07 86.98 Compare UPFC with TCSC 0.24 4.69 1.75 5.24 Table IV shows results of comparison between TCSC and UPFC. The actual real and reactive power losses in the system is 29.50 (MW) and 91.80 (MVAR). Case 1, if the TCSC is connected in the line 11 the real and reactive power losses in the system are 18.90 (MW) and 92.19(MVAR), if the UPFC is connected in the same line 11, the real and reactive power losses in the system is 18.66 (MW) and 87.50(MVAR). Comparing UPFC with TCSC, UPFC can reduce more real (0.24 MW) and reactive (4.69 MVAR) power losses. Similarly inCase2, in which UPFC connected in line 14, reduces more real (1.75 MW) and reactive (5.24 MVAR) power losses. In both cases UPFC gives better performance than TCSC. In all above results, the location of UPFC in the 11th line of the system gives more advantage and better performance. VI. CONCLUSION The power flow study is steady state solution of power system, it help better operation and performance of the systems. The IEEE 14 bus test system has been modeled in MATLAB power system analysis tool box. The power flow solution of the system is carried by Newton -Raphson method. The line flow limit violation is found from load flow solutions. Both real and reactive power losses in the system are minimized with Flexible AC Transmission Systems. Thyristor-Controlled Series Capacitors (TCSC) and Unified Power Flow Controller (UPFC) are most versatile devices in FACTS, which have been selected for test systems and all results are analyzed. This work is useful for optimal power flow problem and location of FACTS in the system in economical point of view. ACKNOWLEDGEMENTS This work has been supported by National Institute of Technology Calicut for Progress Review of PhD Scholar in July 2013.
- 12. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 4, July-August (2013), © IAEME 243 REFERENCES [1] C.L. Wadhwa, “Electical Power Systems”, Fifth Edition, new age international publishers , 2009. [2] P. Srikanth, O. Rajendra, “Load Flow Analysis Of IEEE 14 Bus System Using MATLAB”, International Journal of Engineering Research & Technology (IJERT), Vol. 2 Issue 5, ISSN: 2278-0181, May – 2013. [3] Dharamjit, D.K.Tanti, “Load Flow Analysis on IEEE 30 Bus System”, International Journal of Scientific and Research Publications, Volume 2, Issue 11, November 2012 1 ISSN 2250-3153. [4] N.G. Hingorani, "Flexible AC transmission", IEEE Spectrum, pp.40-45, April 1993. [5] A.K.Chakraborty, S. Majumdar, “Active Line Flow Control of Power System Network with FACTS Devices of choice using Soft Computing Technique”, International Journal of Computer Applications (0975 – 8887) Volume 25– No.9, July 2011. [6] Kamarposhti, Mehrdad Ahmadi; Alinezhad, Mostafa, “Effects of STATCOM, TCSC, SSSC and UPFC on Static Voltage Stability”, page 1376-84, vol.No.4, Nov-Dec 2009. [7] Rajendra B Sadaphale, Vikram S Patil, “Optimal power flow of IEEE 14 bus system using FACTS device with voltage constraints”, International Journal of Advances in Electrical and Electronics Engineering, ISSN: 2319-1112 /V2N1:113-118 ©IJAEEE. [8] Subramanian, G. Ravi, “Optimal Placement of Multi-Type FACTS Devices for Voltage Profile Enhancement”, page5657-5666, Vol.NO 7, october 2012. [9] M. Noroozian and G. Anderson, “Power flow control by use of controllable series components”, IEEE Trans. Power Delivery, vol. 8, no. 3, pp.1420-1429, 1993. [10] Fuerte-Esquivel, C.R. Acha, E. Ambriz-Perez, “ A Thyristor Controlled Series Compensator Model for the Power flow Solution of Practical Power Network”, IEEE Trans. Power System Vol.15 No.1Feb- 2000, pp.58-64. [11] K. W. Louie, P. Wilson, “A New Way to Represent Unified Power Flow Controllers in Power Flow Studies”, 0840-7789/07/$25.00 ©2007 IEEE. [12] L. Gyugyi, C. D. Schauder, and S. L. Williams “The unified power flow controller: a new a pproach to power transmission control”, IEEE Trans. Power Delivery, vol. 10, no. 2, pp.1085- 1097, 1995. [13] M. Mashayekh, A. Kazemi, “A New Approach for Modelling of UPFC In Power Flow and Optimum Power Flow Studies”, 0-7803-9514-X/06/$20.00 ©2006 IEEE. [14] S. M. Shirvani Boroujeni, R. Hemmati, H. Delafkar, A. Safarnezhad Boroujeni, “Simultaneous Power Flow Control and Voltage Support Using UPFC “,page 818-25, vol.no 6,April 2011. [15] M. W. Mustafa, A. A. Mohd Zin, A. F. Abdul kadir, “Steady State Analysis of Power Transmission Using Unified Power Flow Controller”, IEEEconference, pp.2049--2053, 2002. [16] D. Pattanayaka, M. Basub and R. N. Chakrabartic, “Multi-Objective Differential Evolution for Optimal Power Flow”, International Journal of Electrical Engineering & Technology (IJEET), Volume 3, Issue 1, 2012, pp. 31 - 43, ISSN Print : 0976-6545, ISSN Online: 0976-6553. [17] Satyendra Kumar, Dr.Upendra Prasad and Dr.Arbind Kumar Singh, “Employing Facts Devices (Upfc) For Transient Stability Improvement”, International Journal of Electrical Engineering & Technology (IJEET), Volume 4, Issue 3, 2013, pp. 188 - 199, ISSN Print : 0976-6545, ISSN Online: 0976-6553. [18] Tanay Rastogi, Mohd. Tabish Siddiqui, Prof. R.Sudha and Prof. K. Govardhan,, “Analysis of Thyristor Based Hvdc Transmission System”, International Journal of Electrical Engineering & Technology (IJEET), Volume 3, Issue 2, 2012, pp. 29 - 38, ISSN Print : 0976-6545, ISSN Online: 0976-6553.
- 13. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 4, July-August (2013), © IAEME 244 AUTHORS’ INFORMATION Guguloth Ramesh is currently Research Scholar in Electrical Engineering Department, National Institute of Technology, Calicut, Kerala -673601, and India. His is pursuing Ph. D in NIT Calicut. Date of Birth 23-05-1987. He completed B. Tech. at Christu Jyothi Institute of Technology and Science (JNTU Hyderabad) in 2008, M .Tech at NIT Calicut in 2011. His areas of interest and research are Power Systems, Restructuring Power Systems, Flexible AC Transmission System, and Micro grid. He has published one international journal paper in International Review on Modelling and Simulations. Dr .T.K. Sunil Kumar, Assistant Professor, Electrical Engineering Department, NIT Calicut, Kerala -673601, India. He has completed B. Tech at N.S.S College of Engineering Palakkad, M .Tech. at NIT Jamshedpur, and Ph. D. at IIT Kharagpur. His interested areas are Model Matching Controller Design Methods with Applications in Electric Power Systems, Restructuring Power Systems, Flexible AC Transmission System, and Micro grid.

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