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## High Voltage Engineering

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**High Voltage Engineering**Term Project Hazem Hamam 962864**Outline**• Design of AC TL. • Design of DC TL. • Design of a 500kV, 2GW AC TL. • Design of a 400kV, 2GW DC TL. • Economic Comparison. • Conclusion.**Power Transmission**• Importance of power transmission. • Means to transmit and sell power. • Distant energy sources. • Trading energy. • Generation away from cities.**AC Transmission**• Dominated transmission for a long time. • Needs synchronization. • Simple & cheap terminals. • Expensive towers. • Works well for short distances. • Use of models to represent lines.**AC Transmission Design**• PLL at 5% VD, 30-45o AD. • Double or single circuit lines. • Margin to minimize over-loading. • Number of lines=total P/PLL.**AC Transmission Design**• Entering current. • Appropriate conductor’s CCC. • Transformer (TRF) rating. • Conductors between TRF and TL. • Bundling.**AC Transmission Design**• Insulation design criteria. • Withstand of standard unit = 15kv. • Adjacent centers at 0.146m. • Minimum clearance. • Sag and tension. • Tower dimensions.**AC Transmission Design**• TRF protection. • Over-load margin. • CT ratio. • Mismatch. • Percentage operation line. • Pickup value.**Design of 500kv, 2GW AC TL**• PLL = 700MW. • Needs 3 lines, margin 2 lines double circuit. • P/Circuit = 600MW, (670MVA) • I=3376.7A at 380kV. • 4 incoming ACSR1033500,54,7 CCC=1060A.**Design of 500kv, 2GW AC TL**• Each conductor to TRF 380/500kV 700MVA. • TRF Secondary 500kV, 780A. • From TRF Secondary 2 ACSR795,26,7 per bundle CCC=900A to first Tower. • Line Length = 700kM. • Ra=28.175 Ohms.**Design of 500kv, 2GW AC TL**• Inductive reactance=272.033. • Capacitive reactance = 0.0029068. • SIL= 815.1MW. • Is=773.65A. • Ps=603MW. • Vr=512.47kV, V-angle=-0.05o. • Ir=660.7A.**Design of 500kv, 2GW AC TL**• Pr=565.5MW. • Efficiency=93.8%. • Voltage Regulation=54.7%. (Very High) • TSSSL=908.662MW. • PLL=618.16MW.**Design of 500kv, 2GW AC TL**• A withstand voltage of 30kV. • Switching Surge Criteria. • 1 MV Insulation. • 34 Units. • Two Strings for more mechanical Strength. • Min clearance from ground is 12m.**Design of 500kv, 2GW AC TL**• Phase-phase min clearance is 12m. • Surge Arrestors at beginning, 1/3, 2/3 and end of line. • SBD, more wind in the center. • TRF relays slope= 20% pickup 68.6A on 380kV side, 52.8 on 500kV side.**Design of 500kv, 2GW AC TL**• Sag = 7m. • Tension = 31222.4 lb. • Lower circuit of tower’s height =20m. • Upper circuit of tower’s height =32m.**AC Line Diagrams**TRF 1 TRF 5 TRF 2 TRF 6 TRF 3 TRF 7 TRF 4 TRF 8**AC Tower Dimensions**12m 12m 32m 5.678m 20m 25 – 30 m**DC Transmission Design**• Converting Station is expensive. • Converting TRF. • Converting Valve. (quad valves). • AC & DC filtering. • DC Transmission Line. • Pole Configuration • Smaller, Cheaper DC Towers. • Line Commutation.**DC Transmission Design**• 6-pulse configurations. Converting TRF + DC - Thyristor Module**DC Transmission Design**• 12-Pulse Configuration Thyristor Module Mid-point DC bus arrestor AC Side DC Side Thyristor Quad-valve**Design of 400kv, 2GW DC TL**• 400kV DC and 500kV AC. • Converting Valves 400kV. • 4kV thyristors, (100 LTT/valve) • Entering AC is 3380A at 380kV, in 4 ACSR 874500, 54, 7 of CCC 950A. • Every 2 conductors terminate in a HV Bus-Bar at 380kV and 1200MVA.**Design of 400kV, 2GW DC TL**• From BB to Conv.TRF ACSR 874500, 54,7 CCC=950 in 2 conductors/bundle to the TRF. I = 1800A. • The Conv.TRF is a 3-windings 380kV/400kV 1200MVA.**Design of 400kV, 2GW DC TL**After 20m of ACSR 874500, 54, 7cond.: Drops negligible After 40m of ACSR 874500,54,7: Drops and losses negligible Delta winding Bus-Bar at: 380kV 1200MVA 2 conductors entering 1 conductor leaving. TRF protection AC Filters Converter TRF: V=380kV/400kV S=1200MVA 3p 3 windings TRF protection TRF protection 3p ACSR 874500, 54, 7 2 bundles CCC=950A/bund V=380kV S=600MVA I=912A PF=0.9 leading Y winding 3p ACSR 874500,54,7 2 bundles CCC=950A/bund V=380kV S=1200MVA I=1824A**Design of 400kV, 2GW DC TL**Delta Side: V=400kV S=600MVA I=866A Conductors are ACSR 795000,26,7 CCC=900 Length 20 m drops & losses negligible 3000A 866A Mid-point DC bus arrestor + DC - 400kV AC Side Y Side: V=400kV S=600MVA I=866A Conductors are ACSR 795000,26,7 CCC=900 Length 20 m drops & losses negligible 400kV DC Side**Design of 400kV, 2GW DC TL**From the DC side of the converting Valve To the DC side of the converting Valve Transmission Line ACSR 874500, 54, 7 3 bundles per pole CCC per pole = 950A Total I per pole = 2750A R = 17.18 ohms Span = 200 m DC Filters DC Filters V = 352.75kV DC P = 970.08MW I = 2750 V = 400kV DC P = 1100MW I = 2750**Design of 400kV, 2GW DC TL**• Insulation for 800kV. • Number insulator units = 800kV / 30kV = 26.67=27 units/ string. • 12m clearance from phase-phase and phase to neutral. • Surge arrestors at withstand of 1MV. • SA at beginning, 1/3,2/3,end of line.**Design of 400kV, 2GW DC TL**• TRF protection assumes 30% overload. • CT 2400:5 and 1200:5. • Slope is 20%. • 25% pickup means: • 380kV pickup = 115.2A. • 400kV pickup = 56.4A.**Design of 400kV, 2GW DC TL**• Vr = 352.75kV. • Pr= 970.8MW. • Voltage Regulation = 13%. • Voltage Drop = 11%. • Efficiency = 88%.**Design of 400kV, 2GW DC TL**• Lower design than AC is for less voltage. • 500kV DC performance is: • 8.2% Voltage Regulation. • 7.5% Voltage Drop. • 93% efficiency.**Design of 400kV, 2GW DC TL**• Span = 200 M • Sag = 8.94m • Tension = 31433.82 • Pole’s Height 13 + 8.9 =21.9m.**Design of 400kV, 2GW DC TL**Converting Valve Converting Valve TRF 1 TRF 1 Converting Valve Converting Valve TRF 2 TRF 2 Diagram of the Line**Design of 400kV, 2GW DC TL**12m 22m 15-20m DC Tower Dimensions**Economic Comparison**• Break-Even Distance. • AC Cost Estimation Legend: • TRF >500MVA, 1MVA=150$. • AC Towers 200m span = 80,000$. • 1m of conductor for AC = 80$. • DC Cost Estimation Legend: • 1 Station = 10,000,000$. • DC Towers 200m span = 45,000$. • 1m of conductor for AC = 160$.**Equipment**Number Per Unit Price TRF 380/500kV 700MVA 8 105,000$ AC Tower 200m span 3,500 80,000$ AC Conductors 12/m 80$ Converter Station 2 10,000,000$ DC Tower 200m Span 3,500 50,000$ DC Conductors 4/m 160$ Economic Comparison • Table of Equipment:**AC & DC Costs**• 98,644,000 $ for AC TL. • 91,040,000 $ for DC TL.**Conclusion**• AC TL higher Tower and conductor costs and lower terminal costs. • DC TL lower Tower and conductor costs and higher terminal costs. • Economics determines the design to be used. • Line length determines which one is more economic.