1. 05 August 2015 Delft University of Technology Electrical Power System Essentials ET2105 Electrical Power System Essentials Prof. Lou van der Sluis Energy Management Systems

2. 2 6. Energy Management Systems | 18 ET2105 Electrical Power System Essentials Introduction (1) Energy Management Systems (EMS) Supervisory Control and Data Acquisition System (SCADA) State estimator Loadflow or power flow Optimal power flow

3. 3 6. Energy Management Systems | 18 ET2105 Electrical Power System Essentials Introduction (2) Controlled switching Contingency analysis Short circuit computations Stability analysis Reliability analysis

4. 4 6. Energy Management Systems | 18 ET2105 Electrical Power System Essentials Loadflow Computations Input data and results

5. 5 6. Energy Management Systems | 18 ET2105 Electrical Power System Essentials Network Node Types

6. 6 6. Energy Management Systems | 18 ET2105 Electrical Power System Essentials The Admittance Matrix Y

7. 7 6. Energy Management Systems | 18 ET2105 Electrical Power System Essentials Example

8. 8 6. Energy Management Systems | 18 ET2105 Electrical Power System Essentials Loadflow Equations (1) Elements of the Y matrix Voltages of network nodes Injected current at node i

9. 9 6. Energy Management Systems | 18 ET2105 Electrical Power System Essentials Loadflow Equations (2) Injected complex power

10. 10 6. Energy Management Systems | 18 ET2105 Electrical Power System Essentials Loadflow Equations (3) Injected active and reactive power

11. 11 6. Energy Management Systems | 18 ET2105 Electrical Power System Essentials Loadflow Equations (4) To be solved:

12. 12 6. Energy Management Systems | 18 ET2105 Electrical Power System Essentials ExampleLoad Swingbus Z = 0.025+j0.25 P = 0.6 Q = 0.3 |V 1 | = 1  1 = 0 12 iter.  |V 2 | [pu] |V 2 | [pu]  2 [rad]  2 [rad] 01.00000.0000 1-0.09000.9100-0.1425 2-0.02370.8863-0.0185-0.1610 3-0.00090.8853-0.0007-0.1617

13. 13 6. Energy Management Systems | 18 ET2105 Electrical Power System Essentials Make an initial estimation: Calculate the mismatches: Calculate with loadflow equation: Construct the Jacobiaan J Calculatefrom: Add the corrections to the initial estimation: Iterative Loadflow Computation

14. 14 6. Energy Management Systems | 18 ET2105 Electrical Power System Essentials Flowchart of the Newton-Raphson loadflow computation

15. 15 6. Energy Management Systems | 18 ET2105 Electrical Power System Essentials Decoupled Loadflow (1) Resistance of the overhead lines much smaller than the reactance Small differences between the voltage angles Elements of submatrices J 12 and J 21 are rather small Decoupling between active and reactive power

16. 16 6. Energy Management Systems | 18 ET2105 Electrical Power System Essentials Decoupled Loadflow (2)

17. 17 6. Energy Management Systems | 18 ET2105 Electrical Power System Essentials DC Loadflow The non linear equations are linearized Speeds up the computation Not an acurate solution Decoupled loadflow gives an accurate solution

18. 18 6. Energy Management Systems | 18 ET2105 Electrical Power System Essentials State Estimator Input data and results