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Reducing Losses Using Windmil
Reducing Losses Using WindMil Jennifer Taylor Distribution System Solutions, Inc Loss Reduction Analysis Modes • Feeder Optimization • Load Balance • Capacitor Placement Feeder Optimization Feeder Optimization • Aides in finding the optimal location for open points between feeders to best reduce kW losses. Sample Substations kW Losses = 209kW Feeder Optimization Setup Limits the number of switching operations at each step. Adds suggested open points. Feeder Optimization Setup Set limits based on your design criteria: contingency or normal operation? Use inflated overages if you know the capacities aren’t accurately defined in the EQDB. Feeder Optimization Setup Choose colors to display results. Feeder Optimization Results Feeder Optimization Results Feeder Optimization Cost Savings • • • • • Losses before feeder opt.= 209kW 3 pairs of switching = $1500 Losses after balancing = 184kW Reduction in losses = 25kW 30 year present worth = $48,845 Load Balance Load Balance • • • • Voltage shifts: excessive Voltage Drop or Rise Increased return currents Wasted use of capacity Increased losses – The imbalance of current will increase the I2R losses. I2R Losses • Let’s look at a simple math exercise: • Total Current = 600A A B C Balanced Amps I2 200 40,000 200 40,000 200 40,000 Total = 120,000 Imbalanced Amps I2 A 300 90,000 B 200 40,000 C 100 10,000 Total = 140,000 Sample Circuit – Before Balancing 103kW in losses Load Balance Setup Always choose “Fast” Choose whether to run on whole circuit or partial Set up Voltage Drop Sample Circuit – After Balancing 81kW in losses Our Sample Circuit: Loss Savings • • • • • Losses before balancing = 104kW 2 tap phase changes = $500 Losses after balancing = 81kW Reduction in losses = 23kW 30 year present worth = $17,906 Capacitor Placement Capacitor Placement • Increase in net kVAR means an increase in kVA and current levels on the system – Available capacity on equipment decreases – Equipment sizes come into question if they were sized only on kW – Line losses increase (I2R) Capacitor Placement • Proper Capacitor placement becomes essential – Need to know where to place Cap units to provide greatest benefit to our systems – Where to optimize for biggest loss reduction Sample Substation G&T complaining about low power factor at substation • Substation nearing kVA capacity limit • Avg Power Factor = 89.94% • Load Factor = 54.5% • Peak kW = 8,500kW • Peak kVAR = 4,400kVAR Sample Substation 300kVAR closed 600kVAR open VAR profile over one year Week Profile kVAR kW Setting up kVAR in model Known data: • PF at peak at substation = 88.8 • Peak summer kW = 8,500kW • Known power factor at 2 industrial sites Assumptions/Estimates: • Large/Small Commercial pf = 90% • Residential pf = 95% Load Allocation Settings Force kW Demand (Industrial) to swing. Load Allocation Capacitor Placement Setup Set Power Factor desired limits. Capacitor Placement Setup Set Bank size restrictions. Capacitor Placement Setup Set other restrictions on placement. Capacitor Placement Setup Choose color options. Results at full load: Add 600kVAR Add 300KVAR Results at full load: VAR profile: All Fixed 2,100kVAR added Look at Using Some Switched Caps Add in steps as load increases. Adjust for any changes in pf based on load changes. Adding Staged Capacitors 25072: Switched 24917: Switched Keep Existing Fixed 24258: Fixed 56178: Fixed VAR Profile with Added Caps 600 kVAR more switched 1500kVAR fixed Our Sample Sub: Loss Savings • Losses before adding caps = 120kW • Adding one set of controls and one 300kVAR switched bank = $12,000 • Losses after adding caps = 112kW • Reduction in losses = 8kW • 30 year present worth = $16,950 In closing • Even small kW loss reduction can amount to big long-term savings. • Feeder Optimization, Load Balance, and Cap Placement features in WindMil can be great tools to use as starting points for making decisions to make your system more efficient.
