1. CREZ - Voltage Profiles on Series Compensated Lines Prepared by Paul Hassink with AEPSC ERCOT RPG, 11/11/11

2. 11/11/11Prepared by AEPSC WTP2 Series Capacitor (SC) Voltage Profile Characteristics –ERCOT SC installations –CREZ Reactive Study Techniques for Reducing Voltages –Location –Segmentation –Switched Shunts

3. 11/11/11Prepared by AEPSC WTP3 Upgrading Existing 345 kV South Texas system Receiving-end Series Capacitors (12/25 ohm segments) Segmented Series Capacitors (24 ohm)

4. 11/11/11Prepared by AEPSC WTP4 CREZ Series Capacitors Series Capacitor

5. 11/11/11Prepared by AEPSC WTP5 ERCOT CREZ Reactive Power Compensation Study

6. 11/11/11Prepared by AEPSC WTP6 Source End SC Voltages Relative to Impedance Voltage |Impedance| 0%150% line SC MW flow 10%

7. 11/11/11Prepared by AEPSC WTP7 Mid-Line SC Voltages Relative to Impedance Voltage |Impedance| 0%150% ½ of line SC MW flow ½ of line 10%

8. 11/11/11Prepared by AEPSC WTP8 Mid-Line SC Voltages Relative to Impedance Voltage |Impedance| 0%150% ½ of line SC High MW flow ½ of line 10%

9. 11/11/11Prepared by AEPSC WTP9 Voltage Constraints Source and Sink end voltages should be operable across system voltages of 98% to 104% under normal conditions Post contingency, voltages must remain within a 90% to 110% window When voltages fall below 95% or exceed 105%, automatic action must regulate voltages back into voltage window within seconds Voltages within line segments or the series capacitor must be greater than 80% to avoid voltage instability (high reactive losses)

10. 11/11/11Prepared by AEPSC WTP10 Case Study – Big Hill to Kendal Series Capacitors Two Segments at 24 ohms each 3600a continuous and 4000a emergency rating Located within TNC footprint for maintenance and operations Roughly 25% and 50% from sending end (Big Hill)

11. 11/11/11Prepared by AEPSC WTP11 SC Scenarios @ 50% compensation No Series Compensation Sending-end installation in one bank Mid-line installation in one bank Segmented Mid-line installation @ 3600a Segmented Mid-line installation @ 4300a

12. 11/11/11Prepared by AEPSC WTP12 SC Bypassed @ Rated Current 80 o phase shift ~ 150 MW losses ~ continuous rating of SC 80% voltage mid-line 3200 Mvar reactive line losses

13. 11/11/11Prepared by AEPSC WTP13 SC Inserted on Sending-end near Rated Current ~ 120 MW losses 125% voltage 30 o phase shift 2100 Mvar reactive line losses Reactive power enters SC

14. 11/11/11Prepared by AEPSC WTP14 SC Inserted on Sending-end with Capacitor near Rated Current ~ 150 MW losses 116% voltage 37 o phase shift Reactive power exits SC

15. 11/11/11Prepared by AEPSC WTP15 SC Inserted Mid-line Single Segment @ Rated Current ~ 144 MW losses 110% voltage 30 o phase shift ~ continuous rating of SC

16. 11/11/11Prepared by AEPSC WTP16 SC Inserted Mid-line Two Segments @ Rated Current ~ 150 MW losses 3.5% voltage bandwidth ~ continuous rating of SC 30 o phase shift Incremental 400MW

17. 11/11/11Prepared by AEPSC WTP17 SC Inserted Mid-line Two Segments @ Emergency Current ~ 220 MW losses 105% voltage 38 o phase shift Short time emergency rating of SC

18. 11/11/11Prepared by AEPSC WTP18 SC Inserted Mid-line with Capacitor @ Emergency Current ~ 220 MW losses 104% voltage 39 o phase shift Short time emergency rating of SC