Minimizing Impact of Electric Utility Outages with Backup Generation
Introduction of the Speaker Michael Dempsey, PE Senior Electrical Engineer Carter & Burgess, Inc. Energy & Power Solutions
Facility Background Large Financial Institution: Southwestern US Over 5 million square feet 24 x 7 Operations Banking Customer Service Multiple Data Centers Billing Records Claims
Facility Background Two Central Plants North Plant 7500 Tons of Cooling South Plant 6600 Tons of Cooling Multiple Life-Safety Emergency Generator Installations
Facility Background Existing Standby Generator Plant 8-1500kW Diesel Generators 13,800V Distribution Fully Automated Only Serves Portion of Facility South Central Plant Main Data Center Less Than 1/3 Available Office Space
Facility Background Electric Utility Service Primary Distribution 13,800V Two Dedicated Substations Utility Owned Transformers Campus Load Normally Divided Between Substations Normally Open Cross Tie Circuits Available
Mission - Facilitate Continued Business Operations Following Electric Utility Outage Serve Over 4 Million Square Feet of Office Space Serve North Central Plant Serve Banking Operations Existing Standby Generator Plant Unchanged
Electric Load Served by New Generator Plant Approximately 2/3 of Campus Square Footage 2003 Peak Demand 14.5 MW Based on Utility Billing Data 19.4MW Projected Future Peak Demand Based on Full Facility Occupancy
Generator Plant Mode of Operation - Options Standby Only Operate for Utility Outage Simplified Permitting Process Permit by Rule 3 Month Process Standby and Economic Dispatch Operate for Utility Outage Operate to Reduce Energy Cost Significantly More Complicated and Longer Permitting Process New Source Review 18 Month Process Initial Design - Standby
Generator Sizing Packaged Diesel Generators 2MW Standby Rating Max Field Erected Diesel Generators Above 2MW Threshold Redundancy Requirement N+1 Minimum
Generator Ratings Load Factor Average Load/Peak Load Over a Specified Period of Time Accounts for Load Fluctuations Over a Given Period Example Average Load Per Day = 8MW Peak Load Per Day = 10MW Load Factor = 80%
Generator Ratings Standby Power Only Supplied When Utility Source is Unavailable Variable Load Operation Follow Facility Load Fluctuations Not Parallel Operation 80% Load Factor Max 200 Hours Operation Per Year 25 Hours Operation Per Year at 100% Standby Rating
Generator Ratings Prime Variable or Continuous Load Applications Variable Load Operation 70% Load Factor Max Unlimited Hours Operation Per Year 10% Overload for 1 Hour in 12 Hours Not Exceeding 25 Hours Per Year Constant Load Operation Generally Parallel Operation - Peakshave 500 Hours Per Year at 100% Prime Rating
Generator Ratings Cont d Continuous Continuous Load Application 100% Load Factor No Sustained Overload Capability Parallel Operation Base Loaded Unlimited Hours Operation Per Year (Variable Load)
Generator Rating Selected 11 Generators in Parallel 2000kW Standby 1825kW Prime 13,800V 3PH 3W Low Impedance Grounded Minimize Line-to-Ground Short Circuit Current
Fuel System 5 Day Runtime Required Facilitate Extended Utility Outage Operation Redundancy N+1 Fuel tanks Required Automated Fuel Delivery System
Fuel System cont d Options Evaluated Underground Storage Tanks Maintenance Issue Leak Risk Above Ground Storage Tanks Easy Visual Inspection and Maintenance Leaks can be Contained Susceptible to Damage/Fire
Fuel System cont d Above Ground Tanks Selected UL2085 Rated Housed in Enclosed Warehouse Minimize Exposure to Physical Damage 6 30,000 Gallon Tanks 5 Day runtime N+1 Redundancy Supports Future Peak Load» 75% Load Factor Assumed
Electrical Distribution 13,800V Distribution Feeders New Ductbanks Required Connect to Existing Switchgear Main Campus 3 Feeder Circuits Any 2 can Serve Load Banking Facility 2 Feeder Circuits Either 1 can Serve Load
Electrical Distribution cont d Main Campus Cable in Ductbank Installation Cable in Conduit in Utility Tunnel Cable Downsized in Exposed Conduit - $250,000 Savings 500kcmil to 350kcmil 5 Rigid to 4 IMC Banking Facility Cable in Ductbank
Generator Switchgear 13,800V Metalclad 500MVA Interrupting rating Fault Duty Calculated for Parallel Operation Worst Case Breakers Interchangeable with Existing Breakers/Switchgear Sets of 3 Generators Segregated with Tie Breakers Feeder Breakers Segregated with Tie Breakers Ring Bus Configuration
Generator Switchgear cont d Controls Redundant PLCs Redundant Main Touch Screens Bus Differential Low Impedance to Minimize Added CTs Fully Automated Sequence of Operations Generator Load Control Automated Testing with Breaker Operation Remote Workstations Added at Existing Central Plants
Existing Switchgear Modifications Added Circuit Breakers Generator Interconnections Upgraded Voltage Sensing to Three Phase PTs Facility History of PT Problems Added Undervoltage Relays (27) Controlled via Generator Switchgear Added 5 Local Remote terminal Units (RTU) Redundant Fiber Optic Communications
Summary Backup Generator Plant Supports Over 4,000,000 sq ft of Facility Operations Over 10,000 Employees Designed to Serve Future Peak Load 19.4 MW Initially designed for Standby Operation Only Potential Conversion to Parallel Operation for Economic Deployment in Future
Summary 11 Packaged Diesel Generators for N+1 2000kW (Standby Rating) 1825kW (Prime Rating) Be Careful When Specifying Load Rating Fuel System Sized for 5 Days Continuous Operation Distribution Feeder Redundancy N+1 Fully Automated Generator Switchgear Touch Screen Control Redundant PLCs
Questions