High Voltage Engineering

High Voltage EngineeringTerm ProjectHazem Hamam962864

Design of HVAC & HVDC Transmission Lines

OutlineDesign 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 TransmissionImportance of power transmission.Means to transmit and sell power.Distant energy sources.Trading energy.Generation away from cities.

AC TransmissionDominated 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 DesignPLL at 5% VD, 30-45o AD.Double or single circuit lines.Margin to minimize over-loading.Number of lines=total P/PLL.

AC Transmission DesignEntering current.Appropriate conductors CCC.Transformer (TRF) rating.Conductors between TRF and TL.Bundling.

AC Transmission DesignInsulation design criteria.Withstand of standard unit = 15kv.Adjacent centers at 0.146m.Minimum clearance.Sag and tension.Tower dimensions.

AC Transmission DesignTRF protection.Over-load margin.CT ratio.Mismatch.Percentage operation line.Pickup value.

Design of 500kv, 2GW AC TLPLL = 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 TLEach 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 TLInductive 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 TLPr=565.5MW.Efficiency=93.8%.Voltage Regulation=54.7%. (Very High)TSSSL=908.662MW.PLL=618.16MW.

Design of 500kv, 2GW AC TLA 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 TLPhase-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 TLSag = 7m.Tension = 31222.4 lb.Lower circuit of towers height =20m.Upper circuit of towers height =32m.

AC Line DiagramsTRF 1TRF 2TRF 4TRF 3TRF 5TRF 6TRF 8TRF 7

AC Tower Dimensions25 30 m20m12m32m5.678m12m

DC Transmission DesignConverting Station is expensive.Converting TRF.Converting Valve. (quad valves).AC & DC filtering.DC Transmission Line. Pole ConfigurationSmaller, Cheaper DC Towers.Line Commutation.

DC Transmission Design6-pulse configurations.

Converting TRF+DC-

Thyristor Module

DC Transmission Design12-Pulse ConfigurationDC SideAC SideMid-point DC bus arrestorThyristor Quad-valveThyristor Module

Design of 400kv, 2GW DC TL400kV 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 TLFrom 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 TLBus-Bar at: 380kV1200MVA2 conductors entering1 conductor leaving.3p ACSR 874500, 54, 72 bundlesCCC=950A/bundV=380kVS=600MVAI=912APF=0.9 leadingAfter 20m of ACSR 874500, 54, 7cond.:Drops negligible

Converter TRF:V=380kV/400kVS=1200MVA3p 3 windings3p ACSR 874500,54,7 2 bundlesCCC=950A/bundV=380kVS=1200MVAI=1824AAfter 40m of ACSR 874500,54,7:Drops and losses negligibleDelta windingY windingAC FiltersTRF protectionTRF protectionTRF protection

Design of 400kV, 2GW DC TL400kV DC Side400kV AC SideDelta Side:V=400kVS=600MVAI=866AConductors are ACSR 795000,26,7 CCC=900Length 20 m drops & losses negligibleY Side:V=400kVS=600MVAI=866AConductors are ACSR 795000,26,7 CCC=900Length 20 m drops & losses negligible866AMid-point DC bus arrestor+DC-

3000A

Design of 400kV, 2GW DC TLFrom the DC side of the converting ValveDC FiltersTransmission LineACSR 874500, 54, 73 bundles per poleCCC per pole = 950ATotal I per pole = 2750AR = 17.18 ohmsSpan = 200 m

To the DC side of the converting ValveDC FiltersV = 400kV DCP = 1100MWI = 2750

V = 352.75kV DCP = 970.08MWI = 2750

Design of 400kV, 2GW DC TLInsulation 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 TLTRF 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 TLVr = 352.75kV.Pr= 970.8MW.Voltage Regulation = 13%.Voltage Drop = 11%.Efficiency = 88%.

Design of 400kV, 2GW DC TLLower 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 TLSpan = 200 MSag = 8.94mTension = 31433.82Poles Height 13 + 8.9 =21.9m.

Design of 400kV, 2GW DC TLTRF 1TRF 2Converting ValveConverting ValveConverting ValveConverting ValveTRF 2TRF 1Diagram of the Line

Design of 400kV, 2GW DC TL15-20m12m22mDC Tower Dimensions

Economic ComparisonBreak-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$.1m of conductor for AC = 160$.

Economic ComparisonTable of Equipment:

AC & DC Costs98,644,000 $ for AC TL.91,040,000 $ for DC TL.

ConclusionAC 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.