Slide 1

Slide 2 International Standards Contd G59/1 - Recommendations for The Connection of Embedded Generating Plant to The Public Electricity Suppliers Distribution Systems (1991) ( 20kV, 5MW ) G59/1 - Recommendations for The Connection of Embedded Generating Plant to The Public Electricity Suppliers Distribution Systems (1991) ( 20kV, 5MW ) >20kV5MW G75/1 - Recommendations for the connection of embedded generating plant to public distribution systems >20kV or with outputs 5MW G 83/1 Recommendations for connection of Small Scale EG ( Slide 11 IEEE P 1547-2003 STANDARD Influential standard for interconnection of all forms of DR is IEEE 1547-2003, Standard for Interconnecting Distributed Resources with Electric Power Systems. Influential standard for interconnection of all forms of DR is IEEE 1547-2003, Standard for Interconnecting Distributed Resources with Electric Power Systems. IEEE 1547 is the result of a recent effort by SCC21 to develop a single interconnection standard that applies to all technologies. IEEE 1547 is the result of a recent effort by SCC21 to develop a single interconnection standard that applies to all technologies. IEEE 1547 addresses all types of interconnected generation up to 10 MW. IEEE 1547 addresses all types of interconnected generation up to 10 MW. The 1547 standard has benefited greatly from earlier utility industry work documented in IEEE and IEC standards (ANSI- C37 series for protective relaying) The 1547 standard has benefited greatly from earlier utility industry work documented in IEEE and IEC standards (ANSI- C37 series for protective relaying) Slide 12 RECENT CHANGES TO USA GRID CODE (AWEA): Low voltage ride-through (LVRT) capability for wind plants and wind turbines: AWEA recommended adoption of an LVRT requirement developed by E.ON Netz. This is a German grid operator faced with a significant and growing penetration of asynchronous wind generation on the German grid. This standard requires that the machine stay connected for voltages at the terminals as low as 15% of nominal per unit for approximately 0.6 s. Low voltage ride-through (LVRT) capability for wind plants and wind turbines: AWEA recommended adoption of an LVRT requirement developed by E.ON Netz. This is a German grid operator faced with a significant and growing penetration of asynchronous wind generation on the German grid. This standard requires that the machine stay connected for voltages at the terminals as low as 15% of nominal per unit for approximately 0.6 s. Supervisory control and data acquisition (SCADA) equipment for remote control: AWEA recommended the requirement of equipment to enable remote command and control for the limitation of maximum plant output during system emergency and system contingency events. Supervisory control and data acquisition (SCADA) equipment for remote control: AWEA recommended the requirement of equipment to enable remote command and control for the limitation of maximum plant output during system emergency and system contingency events. Reactive power capability: AWEA recommended that wind plants connected to the transmission system be capable of operating over a power factor range of 0.95. Reactive power capability: AWEA recommended that wind plants connected to the transmission system be capable of operating over a power factor range of 0.95. Current wind turbine simulation models: AWEA recommended that major stakeholders (TSOs and WT manuf.) participate in a formal process for developing, updating, and improving engineering models and turbine specifications used for modeling the wind plant interconnection. Current wind turbine simulation models: AWEA recommended that major stakeholders (TSOs and WT manuf.) participate in a formal process for developing, updating, and improving engineering models and turbine specifications used for modeling the wind plant interconnection. Slide 13 RECENT CHANGES TO UK GRID CODE The Grid Code incorporates the technical issues raised by the 3 Licensees with respect to the connection of windfarms: Fault ride through: Requirement for generating units to revert to normal operation when a fault on the network is cleared. Fault ride through: Requirement for generating units to revert to normal operation when a fault on the network is cleared. Power/frequency characteristics: Requirement for generating units to be able to deliver power & remain connected to the network when the system frequency deviates from 50Hz. Power/frequency characteristics: Requirement for generating units to be able to deliver power & remain connected to the network when the system frequency deviates from 50Hz. Frequency control: Requirement for generating plants to be able to increase/decrease power output with falling or rising frequency. Frequency control: Requirement for generating plants to be able to increase/decrease power output with falling or rising frequency. Reactive range and voltage control: Requirement for generating plant to be able to supply lagging/leading reactive power and control the voltage at the grid connection point. Reactive range and voltage control: Requirement for generating plant to be able to supply lagging/leading reactive power and control the voltage at the grid connection point. Negative phase sequence: The requirement for generating units to be able to withstand negative sequence currents caused by phase voltage unbalance and phase to phase faults. Negative phase sequence: The requirement for generating units to be able to withstand negative sequence currents caused by phase voltage unbalance and phase to phase faults. Slide 14 WFPS1.4 FAULT RIDE THROUGH REQUIREMENTS WFPS1.4.1 A Wind Farm Power Station shall remain connected to the Transmission System for Transmission System Voltage dips on any or all phases, where the Transmission System Voltage measured at the HV terminals of the Grid Connected Transformer remains above the heavy black line in Figure WFPS1.1. Slide 15 Connection process overview PROJECT PLANNING PHASE INFORMATION PHASE DESIGN PHASE CONSTRUCTION PHASE TESTING & COMMISSIONING PHASE Slide 16 CATEGORIES OF WIND PLANTS BULK WIND PLANTS: Consist of large wind farms connected to the Transmission System (USA) BULK WIND PLANTS: Consist of large wind farms connected to the Transmission System (USA) DISTRIBUTED WIND PLANTS: refers to single Turbines / small groups of turbines dispersed along Distribution System (popular in Europe, Caribbean ) DISTRIBUTED WIND PLANTS: refers to single Turbines / small groups of turbines dispersed along Distribution System (popular in Europe, Caribbean ) Slide 17 WIND TURBINE CATEGORIES WT divided into two categories which define their electrical characteristics FIXED SPEED DEVICES Simple & Cheap FIXED SPEED DEVICES Simple & Cheap VARIABLE SPEED DEVICES Power Electronic Interface to Grid VARIABLE SPEED DEVICES Power Electronic Interface to Grid M/C RATINGS FROM 600 KW 1.5 MW M/C RATINGS FROM 600 KW 1.5 MW Slide 18 WIND TURBINE TECHNOLOGY FIXED SPEED FSIG: Standard squirrel-cage induction generator connected directly to the grid: These machines have a gearbox to match the rotational speed of blades with that of the generator. Mechanical power may be regulated through an inherent aerodynamic stall characteristic of blades or with active control of blade pitch. FSIG: Standard squirrel-cage induction generator connected directly to the grid: These machines have a gearbox to match the rotational speed of blades with that of the generator. Mechanical power may be regulated through an inherent aerodynamic stall characteristic of blades or with active control of blade pitch. WRIG: Wound-rotor induction generator with variable rotor resistance: These machines have a gearbox for coupling an electrical generator to a turbine hub. They also have pitch control of blades for maximizing energy capture and controlling turbine speed within range of the generator and a small range of variable speed operation (e.g., 10% of generator synchronous speed). WRIG: Wound-rotor induction generator with variable rotor resistance: These machines have a gearbox for coupling an electrical generator to a turbine hub. They also have pitch control of blades for maximizing energy capture and controlling turbine speed within range of the generator and a small range of variable speed operation (e.g., 10% of generator synchronous speed). VARIABLE SPEED DFIG: Doubly fed asynchronous generator: These are essentially wound rotor induction machines with variable frequency excitation of the rotor circuit, incorporating rotor current control via power converter. The rotor circuit power converter may be four-quadrant, allowing independent control of real and reactive flow in either direction (rotor to grid or grid to rotor), or unidirectional real power flow (grid to rotor). These machines have a gearbox for coupling the generator shaft to turbine hub, active control of turbine blade pitch for maximizing production and controlling mechanical speed, and variable speed operation depending on the rating of power converter relative to turbine rating (e.g., 30% of generator synchronous speed). DFIG: Doubly fed asynchronous generator: These are essentially wound rotor induction machines with variable frequency excitation of the rotor circuit, incorporating rotor current control via power converter. The rotor circuit power converter may be four-quadrant, allowing independent control of real and reactive flow in either direction (rotor to grid or grid to rotor), or unidirectional real power flow (grid to rotor). These machines have a gearbox for coupling the generator shaft to turbine hub, active control of turbine blade pitch for maximizing production and controlling mechanical speed, and variable speed operation depending on the rating of power converter relative to turbine rating (e.g., 30% of generator synchronous speed). Synchronous or induction generator with full- size power converter: In these machines, the generator is coupled to the grid through a fully rated ac/dc/ac power converter. They also have a gearbox to match generator speed to variable rotational speed of blades and variable speed operation over a wide range, depending on electrical generator characteristics. Synchronous or induction generator with full- size power converter: In these machines, the generator is coupled to the grid through a fully rated ac/dc/ac power converter. They also have a gearbox to match generator speed to variable rotational speed of blades and variable speed operation over a wide range, depending on electrical generator characteristics. Slide 19 CAPACITY FACTORS The Declared Net Capacity (DNC) of a generation scheme is a measure of the expected average power output of the generation scheme. DNC = (RATED POWER OUTPUT POWER CONSUMED BY PLANT) X CF Capacity factor for wave energy schemes = 0.33 Capacity factor for wind energy schemes = 0.43 Capacity factor for other types of C-2 generation schemes = 1.00 Slide 20 POW. SYS. ANALYSIS FOR DISTRIBUTED WIND: Voltage Regulation POWER QUALITY- FLICKER, HARMONICS Short Circuit Contribution Slide 21 Pow. Sys. Analysis Issues for Bulk Wind include: Var Support Capacity Constraints Stability Reserve Capacity Requirements Slide 22 Factors Impacting System Voltage Local Wind Profile (Speed, Turbulence, Shear) Local Wind Profile (Speed, Turbulence, Shear) Size of Wind Turbine to Short Circuit ratio Size of Wind Turbine to Short Circuit ratio X/R Ratio of system X/R Ratio of system Type of WTG and associated Reactive Power Control Type of WTG and associated Reactive Power Control Loading on Distribution Feeder Loading on Distribution Feeder Slide 23 VOLTAGE REGULATION: Commercial WTG employ Reactive Compensation Commercial WTG employ Reactive Compensation Variable Speed Gen. use Static Var. Control to adjust current phase angle Variable Speed Gen. use Static Var. Control to adjust current phase angle Fixed and semi variable speed IG use switched capacitor banks Fixed and semi variable speed IG use switched capacitor banks Need to Coordinate with other Voltage Reg. devices e.g. Regulator/switched Caps. Need to Coordinate with other Voltage Reg. devices e.g. Regulator/switched Caps. Slide 24 POWER QUALITY VOLTAGE FLICKER - Refers to the rapid variations in voltage levels within a certain Mag. and Freq. range VOLTAGE FLICKER - Refers to the rapid variations in voltage levels within a certain Mag. and Freq. range Synonymous with light or lamp flicker Synonymous with light or lamp flicker Arises due to abrupt changes in WT Pow. O/P- Wind Gusting & Variable Dynamic behaviour Arises due to abrupt changes in WT Pow. O/P- Wind Gusting & Variable Dynamic behaviour Fluctuations at freq. close to 8 Hz cause most annoyance Fluctuations at freq. close to 8 Hz cause most annoyance Occurs on weak systems with low X/R ratio Occurs on weak systems with low X/R ratio Slide 25 VOLTAGE FLICKER IMPACT Peculiar to Fixed speed devices Peculiar to Fixed speed devices Variable speed WT less likely to cause flicker Variable speed WT less likely to cause flicker Wind farm with several turbines less likely to cause flicker as variations of Pow. O/P tend to cancel out. Wind farm with several turbines less likely to cause flicker as variations of Pow. O/P tend to cancel out. Slide 26 CAUSES OF FLICKER BY WTG Blade passing of tower results in oscillations Blade passing of tower results in oscillations Variations of wind speed Variations of wind speed Switching operations- startup & shutdown Switching operations- startup & shutdown Recommended limits on flicker in Dist. Networks addressed in IEC 61400.21 Recommended limits on flicker in Dist. Networks addressed in IEC 61400.21 Slide 27 SHORT CIRCUIT CONTRIBUTION For WTG in 600 kw - 1.3 MW range must consider Fault Contribution For WTG in 600 kw - 1.3 MW range must consider Fault Contribution 80-90% of Dist faults are SLG which cause m/c to receive normal excitation voltage 80-90% of Dist faults are SLG which cause m/c to receive normal excitation voltage For voltage > 60% treat IG as Synch. m/c. (Rule of thumb by W. Feero) For voltage > 60% treat IG as Synch. m/c. (Rule of thumb by W. Feero) Obtain Static Ind. m/c model more accurate Obtain Static Ind. m/c model more accurate Slide 28 NETWORK EFFECT OF GEN. TECH. Slide 29 EFFECTS DUE TO FAULT CONTRIBUTION REDUCTION OF RELAY REACH REDUCTION OF RELAY REACH SYMPATHETIC TRIPPING OF BREAKERS/RECLOSERS SYMPATHETIC TRIPPING OF BREAKERS/RECLOSERS COORDINATION ISSUES- DELAYED AUTO-RECLOSING 3-5 secs. COORDINATION ISSUES- DELAYED AUTO-RECLOSING 3-5 secs. Slide 30 Network Design for WTG Connection CONNECTION VOLTAGE 24 KV, 69 KV CONNECTION VOLTAGE 24 KV, 69 KV NETWORK FAULT LEVEL NETWORK FAULT LEVEL SYSTEM X/R RATIO SYSTEM X/R RATIO NETWORK CAPACITY AT PCC THERMAL RATINGS, EXP. REQMENTS, VOLT. REGULATION NETWORK CAPACITY AT PCC THERMAL RATINGS, EXP. REQMENTS, VOLT. REGULATION Slide 31 WF POWER EQUATION Where, = air density (nominally 1.22 kg/m3) R = radius of area swept by the turbine blades V = speed of moving air stream Cp = coefficient of performance for the composite airfoil (rotating blades) Slide 32 VAR SUPPORT WIND FARMS TYPICALLY NOT USED TO PROVIDE VOLTAGE CONTROL WIND FARMS TYPICALLY NOT USED TO PROVIDE VOLTAGE CONTROL CAN PROVIDE LOCAL VOLTAGE REGULATION FOR WEAK SYSTEMS CAN PROVIDE LOCAL VOLTAGE REGULATION FOR WEAK SYSTEMS FLUCTUATING WIND PLANT O/P MEANS AMT. OF REACTIVE POW. REQD VARIES FLUCTUATING WIND PLANT O/P MEANS AMT. OF REACTIVE POW. REQD VARIES FAILURE TO MAINTAIN REACTIVE Q LEADS TO VOLTAGE COLLAPSE AS WTG O/P INCREASES FAILURE TO MAINTAIN REACTIVE Q LEADS TO VOLTAGE COLLAPSE AS WTG O/P INCREASES Slide 33 REACTIVE COMPENSATION TECHNIQUES: CONSTANT PF - Switched Cap. Banks at each WTG provide constant PF over range of Gen O/P CONSTANT PF - Switched Cap. Banks at each WTG provide constant PF over range of Gen O/P VARIABLE PF Real time control of each WTG reactive Q production or absorption VARIABLE PF Real time control of each WTG reactive Q production or absorption SUBS. SWITCHED CAP. BANKS Large Cap banks located at interconnection Sub. SUBS. SWITCHED CAP. BANKS Large Cap banks located at interconnection Sub. STATCOM FACTS devices that use voltage source converters to provide reactive current. STATCOM FACTS devices that use voltage source converters to provide reactive current. Slide 34 POWER SYSTEM STABILITY Full Assessment of Network performance requires study of STEADY STATE and TRANSIENT STABILITY operation Full Assessment of Network performance requires study of STEADY STATE and TRANSIENT STABILITY operation Characteristics of WTG must not compromise the stability of Power System following CONTINGENCY Characteristics of WTG must not compromise the stability of Power System following CONTINGENCY Slide 35 DEFINITION OF STABILITY STEADY STATE STABILITY - Ability of Pow. Sys. to remain stable after a small disturbance e.g load disturbance, switching STEADY STATE STABILITY - Ability of Pow. Sys. to remain stable after a small disturbance e.g load disturbance, switching TRANSIENT STABILITY ability of Pow. Sys. to maintain synchronism after a severe transient disturbance. E.g. Short Circuits, loss of load or Gen. TRANSIENT STABILITY ability of Pow. Sys. to maintain synchronism after a severe transient disturbance. E.g. Short Circuits, loss of load or Gen. Slide 36 PURPOSE OF TRANS. STAB. STUDY TO PREDICT ABILITY OF GEN. TO RECOVER AND REMAIN CONNECTED TO POWER SYSTEM AFTER A FAULT TO PREDICT ABILITY OF GEN. TO RECOVER AND REMAIN CONNECTED TO POWER SYSTEM AFTER A FAULT TO ASSESS INTERACTION OF GENS. AND OTHER ROTATING PLANT (WTG) CONNECTED TO NETWORK AFTER FAULT TO ASSESS INTERACTION OF GENS. AND OTHER ROTATING PLANT (WTG) CONNECTED TO NETWORK AFTER FAULT TO ENSURE MINIMUM VOLTAGE DISTURBANCE DUE TO LOSS OF SYNCHRONISM TO ENSURE MINIMUM VOLTAGE DISTURBANCE DUE TO LOSS OF SYNCHRONISM Slide 37 SMALL SIGNAL STABILITY Two forms of Instability occur under these conditions: Steady Increase in Rotor Angle due to lack of sufficient Synchronising Torque Steady Increase in Rotor Angle due to lack of sufficient Synchronising Torque Rotor oscillations of increasing amplitude due to lack of sufficient damping torque Rotor oscillations of increasing amplitude due to lack of sufficient damping torque Slide 38 TRANSIENT STABILITY CONSIDERATIONS In large complex power systems Transient instability may not always occur as first Swing Instability, but may be due to superposition of several modes of oscillations. In large complex power systems Transient instability may not always occur as first Swing Instability, but may be due to superposition of several modes of oscillations. Analysing TS - the study period is 3-5 secs. after disturbance. May be extended to 10 secs. or more. Analysing TS - the study period is 3-5 secs. after disturbance. May be extended to 10 secs. or more. Slide 39 STABILITY CHALLENGES CAUSES SHORT CIRCUITS SHORT CIRCUITS LOSS OF TIE LINES IN UTILITY NETWORK LOSS OF TIE LINES IN UTILITY NETWORK LOSS OF GENERATION LOSS OF GENERATION SWITCHING OPERATIONS OF LINES, CAPACITORS ETC. SWITCHING OPERATIONS OF LINES, CAPACITORS ETC. SUDDEN LARGE STEP CHANGE OF GENERATION SUDDEN LARGE STEP CHANGE OF GENERATION CONSEQUENCES AREA WIDE BLACK OUT AREA WIDE BLACK OUT INTERRUPTION OF LOAD INTERRUPTION OF LOAD UNDER VOLTAGE CONDITION UNDER VOLTAGE CONDITION DAMAGE TO EQUIPMENT DAMAGE TO EQUIPMENT RELAY AND PROTECTIVE DEVICE MALFUNCTION RELAY AND PROTECTIVE DEVICE MALFUNCTION Slide 40 SYSTEM OR NETWORK STUDY LOAD FLOW STUDY LOAD FLOW STUDY TRANSIENT STABILITY STUDY TRANSIENT STABILITY STUDY DYNAMIC SECURITY ASSESSMENT DYNAMIC SECURITY ASSESSMENT COMMERCIAL SOFTWARE PSS/E PTI LTD. PSS/E PTI LTD. ERACS ERA LTD. ERACS ERA LTD. IPSA IPSA POWER/UMIST IPSA IPSA POWER/UMIST ETAP OTI INC. ETAP OTI INC. MATLAB / SIMULINK MATLAB / SIMULINK Slide 41 PS STUDY CONSIDERATIONS LOAD FLOWS LOAD FLOWS CURRENT FLOWS IN EACH BRANCH OF NETWORK CURRENT FLOWS IN EACH BRANCH OF NETWORK REAL & REACTIVE POWER FLOWS REAL & REACTIVE POWER FLOWS VOLTAGES AT EACH NODE VOLTAGES AT EACH NODE VOLTAGE BOOST AT CONTROL NODES VOLTAGE BOOST AT CONTROL NODES LOSSES LOSSES Slide 42 FAULT LEVEL STUDIES TOTAL FAULT CURRENT AT FAULTED NODE TOTAL FAULT CURRENT AT FAULTED NODE ANGLE OF FAULT CURRENT RELATIVE TO REFERENCE VOLTAGE ANGLE OF FAULT CURRENT RELATIVE TO REFERENCE VOLTAGE FAULT CURRENT DISTRIBUTION FAULT CURRENT DISTRIBUTION (CRITICAL TO PROTECTION) (CRITICAL TO PROTECTION) Slide 43 LOAD FLOW ANALYSIS Slide 44 MATLAB/POWERSIM Slide 45 ETAP 5.5.0 Slide 46 ETAP 5.5.0 FEATURES Slide 47 MODELLING ISSUES DFIG MODELLED ALL PARTS MODELLED FOR DYNAMIC STUDIES DFIG MODELLED ALL PARTS MODELLED FOR DYNAMIC STUDIES AERODYNAMICS AERODYNAMICS TURBINE TURBINE DRIVE TRAIN - GEARBOX DRIVE TRAIN - GEARBOX GENERATOR GENERATOR CONTROL SYSTEM CONTROL SYSTEM Slide 48 WIND FARM MODELLING Modelling WF requires grouping of m/cs of similar type into an equivalent single m/c Modelling WF requires grouping of m/cs of similar type into an equivalent single m/c Large WF can be split into several equiv. m/cs Large WF can be split into several equiv. m/cs Layout of WG to be taken into account as this affects regulation and dynamic behaviour especially of variable speed m/cs. Layout of WG to be taken into account as this affects regulation and dynamic behaviour especially of variable speed m/cs. Consider Loss of accuracy vs. simplified practical model Consider Loss of accuracy vs. simplified practical model Slide 49 SIMULATION STUDY TRANSIENT STABILITY STUDIES PERFORMED FOR (up to 7 secs): TRANSIENT STABILITY STUDIES PERFORMED FOR (up to 7 secs): CONTINGENCY ON OHL INFEEDS AND WF CKT CONTINGENCY ON OHL INFEEDS AND WF CKT CONTINGENCY ON UG CABLES CONTINGENCY ON UG CABLES LOSS OF GENERATION LOSS OF GENERATION BUS FAULT BUS FAULT WIND GUST WIND GUST Slide 50 SYMETRICAL LV TOLERANCE CURVE Slide 51 EQUAL AREA CRITERION: Divide the machines in the system into two groups: Divide the machines in the system into two groups: the critical machines that are responsible for the loss of synchronism, and the remaining non critical ones the critical machines that are responsible for the loss of synchronism, and the remaining non critical ones Replace the two groups by two equivalent. machines. Replace the two groups by two equivalent. machines. Replace these machines by an equivalent single machine, infinite bus system. Replace these machines by an equivalent single machine, infinite bus system. Evaluate the system stability using the equal area criterion. Evaluate the system stability using the equal area criterion. Slide 52 WF SINGLE LINE SIMULATION Slide 53 CONVERTER Slide 54 WT MODEL: Cp CURVES Slide 55 WT AERODYNAMICS MODEL Slide 56 CONVERTER CONTROL Slide 57 MACHINE INERTIA CONSTANTS Slide 58 DFIG MODEL SETUP Slide 59 WIND CHARACTERISTIC MODEL Slide 60 ST-NO-OHL-FLT-L25SIM Slide 61 ST-NO-OHLFLT-L11-PROTSIM Slide 62 ST-NO-OHLFLT-L25BFSIM Slide 63 TS- ST-CE-OHLFLT- V & I Slide 64 TS-ST-CE-OHLFLT- P & Q POWER Slide 65 ST-CE-OHLFLT-SPEED & MECH. POWER Slide 66 TS- CH-STUGCABFLTBF Slide 67 Slide 68 TS- CH-STCABBF MECH. POW & SPEED Slide 69 WFT-WIND GUST Slide 70 SWING CURVES: SG 24 BUS FAULT Slide 71 SWING CURVES- NORTH 24 BUS FAULT Slide 72 CONCLUSIONS: BLPC TO ADOPT RELEVANT INTL STANDARDS- FORMULATE INTERCON. GRID CODES BLPC TO ADOPT RELEVANT INTL STANDARDS- FORMULATE INTERCON. GRID CODES DFIG HAVE CAPACITY TO ASSIST STABILITY DURING POWER SYSTEM DISTURBANCE DFIG HAVE CAPACITY TO ASSIST STABILITY DURING POWER SYSTEM DISTURBANCE SIMULATIONS NEEDED TO TEST DFIG & MANUF. M/C PARAMETERS FOR LVRT REQUIREMENT & STABILITY ENHANCEMENTS SIMULATIONS NEEDED TO TEST DFIG & MANUF. M/C PARAMETERS FOR LVRT REQUIREMENT & STABILITY ENHANCEMENTS PROTECTION PHILOSOPHY TO BE ADOPTED w.r.t. WFT INTERCONNECTION PROTECTION PHILOSOPHY TO BE ADOPTED w.r.t. WFT INTERCONNECTION Slide 73 COMPARISON OF WT TO TALLEST BUILDING BDOS CENTRAL BANK BDOS CENTRAL BANK Typical 850/900 kW Wind Turbine Generator 52m Rotor Diameter 50m Hub Height Slide 74 QUESTIONS?