CREZ - Voltage Profiles on Series Compensated Lines Prepared by Paul Hassink with AEPSC ERCOT RPG, 11/11/11 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 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) 11/11/11Prepared by AEPSC WTP4 CREZ Series Capacitors Series Capacitor 11/11/11Prepared by AEPSC WTP5 ERCOT CREZ Reactive Power Compensation Study 11/11/11Prepared by AEPSC WTP6 Source End SC Voltages Relative to Impedance Voltage |Impedance| 0%150% line SC MW flow 10% 11/11/11Prepared by AEPSC WTP7 Mid-Line SC Voltages Relative to Impedance Voltage |Impedance| 0%150% of line SC MW flow of line 10% 11/11/11Prepared by AEPSC WTP8 Mid-Line SC Voltages Relative to Impedance Voltage |Impedance| 0%150% of line SC High MW flow of line 10% 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) 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) 11/11/11Prepared by AEPSC WTP11 SC 50% compensation No Series Compensation Sending-end installation in one bank Mid-line installation in one bank Segmented Mid-line 3600a Segmented Mid-line 4300a 11/11/11Prepared by AEPSC WTP12 SC Rated Current 80 o phase shift ~ 150 MW losses ~ continuous rating of SC 80% voltage mid-line 3200 Mvar reactive line losses 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 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 11/11/11Prepared by AEPSC WTP15 SC Inserted Mid-line Single Rated Current ~ 144 MW losses 110% voltage 30 o phase shift ~ continuous rating of SC 11/11/11Prepared by AEPSC WTP16 SC Inserted Mid-line Two Rated Current ~ 150 MW losses 3.5% voltage bandwidth ~ continuous rating of SC 30 o phase shift Incremental 400MW 11/11/11Prepared by AEPSC WTP17 SC Inserted Mid-line Two Emergency Current ~ 220 MW losses 105% voltage 38 o phase shift Short time emergency rating of SC 11/11/11Prepared by AEPSC WTP18 SC Inserted Mid-line with Emergency Current ~ 220 MW losses 104% voltage 39 o phase shift Short time emergency rating of SC