Slide 1
-:Prepared by:- Divyangkumar R Soni. (160410707008)Optimal Placement of FACTS Controller
-:Guided By:-Dr. P. R. GandhiPh.D(Electrical) (Asst.prof.)Electrical Engg. Dept.
PAPERSMulti-objective Fuzzy-GA Formulation for Optimal Placement and Sizing of Shunt FACTS Controller
AUTHORS
A. R. Phadke*, Manoj Fozdar**, K. R. Niazi*** 28-Mar-172
OUTLINE28-Mar-17
3AbstractIntroductionFuzzy Membership FunctionsGA ImplementationSimulation And Results References
ABSTRACTThe location and sizing of FACTS controllers for voltage stability enhancement is an important consideration for practical power systems. A strategy for placement and sizing of shunt FACTS controller using Fuzzy logic and Real Coded Genetic Algorithm is proposed. A fuzzy performance index based on distance to saddle-node bifurcation, voltage profile and capacity of shunt FACTS controller is proposed. The proposed technique can be used to find the most effective location and optimal size of the shunt FACTS devices.The proposed approach has been applied on IEEE 14-bus test system.28-Mar-174
INTRODUCTIONThe continual increase in demand for electric power has forced utility companies to operate their systems closer to the limits of instability. One of the major problems that may associate with such a stressed system is voltage instability or voltage collapse. Under stressed condition, one way to save the system from voltage collapse is to provide reactive power support with shunt FACTS controllers at appropriate locations. The techniques used for optimal placement of FACTS devices can be broadly classified into : Index based methods Optimization based methods28-Mar-175
MULTI-OBJECTIVE FORMULATION FOR PLACEMENT AND SIZING OF SHUNT FACTS CONTROLLER 28-Mar-17
6Shunt FACTS controller like SVC or STATCOM connected at the appropriate location results in prevention of voltage collapse and better voltage profile.Placing of shunt FACTS controller can be formulated as a multi-objective problem with the following objectives and constraints. Maximum distance to saddle-node bifurcation Minimum voltage deviationMinimum size of the shunt FACTS device
Maximum distance to saddle-node bifurcationSaddle-node bifurcation point give the information loading margin.Loading margin is defined as the distance between the current operating point and the saddle-node bifurcation or voltage collapse point.Saddle-node bifurcation is identified by a zero eigenvalue associated with system Jacobian.the first objective can be expressed as:Max f1 = min(eig(J)) . . . . . (1)Where, min(eig(J)) = the minimum eigen value of the system Jacobian. 28-Mar-177
Minimum voltage deviationThe Excessively low voltages can lead to an unacceptable service quality and can create voltage instability problems.Shunt FACTS devices connected at the appropriate location play a leading role in improving voltage profile and avoiding the voltage collapse in the power system. the second objective can be expressed as : Min f2 = | v mref - vm | . . . . .(2)
(m=1 to k)Where , Vm = the voltage magnitude at bus m. Vmref = the nominal voltage of bus m and k is the number of buses for which bus voltage limit is violated. 28-Mar-178
Minimum size of shut FACTS deviceDue to the high installation cost of FACTS controllers, these controllers should be optimally sized. Thus, third important objective is to have minimum possible size of the shunt FACTS devices. This objective can be expressed as : min f3 = ci . . . . . (3)
(i=1 to sf)Where, Ci = the capacity of the ith shunt FACTS device in p.u. sf = the total number of shunt FACTS devices. 28-Mar-179
During normal operation, power system is required to satisfy some constraints.Load constraint: The load constraints are the active and reactive power balance equations .It can be expressed in a compact form as :g(x,u) = 0. . . . . (4)Where , g = the equality constraint
Operational constraint :These constraints can be represented in a compact form as : h(x,u) Max gen?Run Power FlowCompute Fitness functionApply GA operators: Selection, Crossover and MutationSTOP
yesnoF = i * Vpi * ci Read system data and initialize GA parameterGen >Max gen?Run Power FlowCompute Fitness function
SIMULATION AND RESULTS 28-Mar-17
15The applicability of the proposed method has been tested on IEEE 14-bus system. Optimal location and size of the shunt FACTS controller was determined by applying the proposed fuzzy-GA approach. Which accurately represents the active and reactive power flows to and from the voltage source converter of the STATCOM.The voltage at the STATCOM bus is given by :V= Vref + IX SL . . . . . (7)V= Vref - IX SL . . . . . (8) where , XSL = the controller droop. Vref = reference voltage.
SIL Of IEEE 14 Bus System 28-Mar-17
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There are 20 branches and 14 buses with 11 loads totaling 259 MW and 77.4 MVAR at base case.
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17The fitness function F was computed at a loading factor close to the voltage collapse condition in order to consider generator reactive power limits and nonlinearity. The application results of the proposed method are shown in below Table I.
Table I. Maximum Value Of Fitness Function And Corresponding Membership Functions With STATCOM At Candidate Buses In IEEE 14-bus Test System28-Mar-17
18Bus no. i Vpi ci F40.9846030.9619740.4256320.40314250.9675060.8592460.451140.37585590.8690410.8121580.8607140.607491100.7891960.6945040.9068880.497065110.711030.3531760.9694830.243455120.6030240.000.6116620.00130.7243710.3653860.9593210.253908140.6801080.6010620.9432610.385593
F = i * Vpi * ci F= 0.869041 * 0.812158 * 0.860714 F=0.607491
Figure 3. Evolution of the fitness function with respect to number of generations for bus no. 9 in IEEE 14 bus system.28-Mar-17
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Best Fitness Value Is Achieved In About 25 Generation For STATCOM
Figure 4. The PV Curves Of The System Without STATCOM, And With STATCOM At Bus No. 9 And Bus No. 14. 28-Mar-17
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The loading margin of the system increases from 0.69381 to 0.87848 and 0.88570 for the STATCOM connected at bus 14 and 9 respectively
Figure 5. Voltage Profile Of IEEE 14-bus System Without STATCOM And With STATCOM At Bus 9 And 14 At a Loading Factor Of = 0.428-Mar-17
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It may be observed that STATCOM connected at bus no. 9 provides the best improvement in voltage profile.
CONCLUSIONS28-Mar-17
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The proposed method determines a bus which is strongly tied with the number of weak buses. Placement of shunt FACTS controller at this bus results in optimal reactive power reinforcement for voltage stability enhancement as compared to the shunt FACTS controller connected at the weakest bus or in weak area.
The Weak Zone Strongly Tied With The Number Of Weak Buses
REFERENCES 28-Mar-17
23 C. A. Canizares, M. Pozzi, S. Corsi and E. Uzunovic, STATCOM modeling for voltage and angle stability studies, Elect. Power and Energy Syst., vol. 25, pp. 431441, 2003. B. Gao, G.K. Morison and P. Kundur, Voltage stability evaluation using modal analysis, IEEE Trans. on Power Syst., vol. 7, No. 4, pp. 1529-1542, 1992.N. K. Sharma, A. Ghosh and R. K. Varma, A novel placement strategy for FACTS controllers, IEEE Trans. on Power Syst., vol. 18, pp. 982 987, 2003.
Thank you28-Mar-17
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