1. 1 / 24 Analysis of Estimated Problems Using ETAP During Installing a Synchronous Condenser in Wolsong#2 2005.10.22 Young Seung Lee

2. 2 / 24 Table of Contents 1.Introduction 2.Modeling of Equipment 3.Methods of Analyses 4.Simulation Using Electrical Transient Analysis Program (ETAP) PowerStation 5.Summaries and Further Works 6.References

3. 3 / 24 Introduction If installing a synchronous condenser (SC), we can estimate problems such as increasing short circuit currents and the time required for the residual voltage to decay. I will present modeling of power systems and methods of analyses for knowing how to work in ETAP. Base on data of Wolsong#2, estimated problems are analyzed using ETAP.

4. 4 / 24 Modeling of Equipment Passive elements and active elements Passive elements The passive elements comprise such components as transmission lines, transformers, reactors, and capacitors. They are regarded as linear. The lowercase letters represent the time-varying functions of voltage and current.

5. 5 / 24 Modeling of Equipment Active elements The Active elements comprise such components as motors, generators, synchronous condensers, and other loads such as furnaces. They are regarded as nonlinear. Referenced units

6. 6 / 24 Modeling of Equipment Referenced units (continued)

7. 7 / 24 Modeling of Equipment Models of branch elements Lines Four parameters: r, X L, g, b c Long lines (>150 miles) Medium lines (50< l <150 miles) short lines (<50 miles)

8. 8 / 24 Modeling of Equipment Cables The overhead line models are equally applicable to cables. Though the resistances are substantially the same, the relative values of reactances are vastly different. The cable inductive reactance is about ¼ that of the line but the capacitive reactance is 30-40 times that of the line. Transformers

9. 9 / 24 Modeling of Equipment Induction motors Synchronous machines

10. 10 / 24 Methods of Analyses Fundamental methods for solving circuit problems Linearity Superposition Thevenin and Norton equivalent circuits Sinusoidal forcing function Phasor representation Fourier representation Laplace transform Single-phase equivalent circuit Symmetrical component analysis Per unit method

11. 11 / 24 Methods of Analyses Fundamental methods for solving circuit problems (continued)

12. 12 / 24 Methods of Analyses Fundamental methods for solving circuit problems (continued)

13. 13 / 24 Methods of Analyses Fundamental methods for solving circuit problems (continued) Per-unit representations: In power system calculations, variables are routinely expressed using the per-unit system instead of actual quantities such as ohms, volts, etc.

14. 14 / 24 Methods of Analyses Iterative methods for solving circuit problems Gauss-Seidel iterative method: It is a simple substitution technique in which a variable calculated using one equation is substituted in the following equations to calculate other variables. The calculations are repeated until the results match the previous iteration within a specified tolerance. Newton-Raphson iterative method: Given an equation in the form f (x) = 0, we can graph the function as y = f (x). The solution of the equation is the x- coordinate where the curve crosses the x-axis (i.e., y = 0). If an initial guess at the solution of x0 is made, the corresponding y-coordinate can be calculated as y0 = f (x0). A line tangent to the curve can be drawn at (x0, y0). The x-coordinate (x1) at which this line crosses the x-axis will be a closer approximation to the actual solution.

15. 15 / 24 Simulation Using ETAP Harmonic analysis The original circuit

16. 16 / 24 Simulation Using ETAP Harmonic analysis Installing a synchronous condenser

17. 17 / 24 Simulation Using ETAP Harmonic analysis Installing a capacitor

18. 18 / 24 Simulation Using ETAP Short circuit current analysis 3 phase short circuit in bus 7 without SC

19. 19 / 24 Simulation Using ETAP Short circuit current analysis 3 phase short circuit in bus 7 with SC

20. 20 / 24 Simulation Using ETAP Transient analysis Without SC

21. 21 / 24 Simulation Using ETAP Transient analysis With SC

22. 22 / 24 Simulation Using ETAP Transient analysis Decayed time of terminal voltage

23. 23 / 24 Summaries and Further Works Summaries For the simulation, modeling of power system was understood. For the power factor correction, a SC is better than a capacitor in point of harmonics. Though we install a SC, interrupting capacity of circuit breakers is not exceeded. During bus transfer, bus voltage is maintained above 80%, and decayed time of residual voltage is the same as that of original circuit. (0.621s, <30%) Therefore, the SC for power factor correction do not cause problems. Further work Analysis of economical efficiency for power factor correction will be performed in detail.

24. 24 / 24 References IEEE Std 399-1997, IEEE Recommended Practice for Industrial and Commercial Power System Analysis Report, KHNP “Development on the Electrical Analysis Technique for the Auxiliary Power System of Nuclear Power Plant”