southern company interconnection process -...
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Southern CompanyInterconnection Process
Dexter LewisResearch EngineerResearch and Technology ManagementSouthern Company
Outline
• Southern Company• GPC Solar • Interconnection Process
–Application requirements–Distribution impact study–Witness Testing
Southern Company
Southern Company
• 45,502 MW of generating capacity– 41% natural gas, 37% coal, 16% nuclear, 6% hydro– PV – 60 MW with 115MW in application process– Hydro – 2,785 MW of generating capacity with 16MW of new capacity planned for next 5 years
– Biomass – 128 MW– Landfill Gas – 3.2 MW landfill gas generator in Gulf Power Service Territory
Georgia Power Solar• Georgia Public Service Commission adopted a motion that
requires Georgia Power Company to bring online 260MW of solar capacity by 2015 and 265MW by 2017 (525MW total).– 100MW of distributed small‐scale generation– 425MW of utility‐scale solar
• Small generators ( 100 ) are eligible to sell their electricity under the Renewable & Non‐renewable Tariff (RNR‐7) and the Solar Purchase Tariff (SP‐1). Larger customers ( 80 ) may sell their electricity as a Qualifying Facility– RNR‐7 – Company will pay avoided cost– SP‐1 – Company will purchase at 17.00 cents/kWh
GPC Number of Interconnection Requests
1 to 65 Inter
GPC kW Installed/Proposed/Anticipated
1 to 5000kW
GPC Average kW per Interconnection
1 to 1000kw/Inter
GPC Interconnection Process
Customer Submits Application Package
GPC Processes & Reviews Application
Package
GPC and Customer Site Visits
GPC Conducts Distribution System
Studies
GPC Conducts Interconnection Equipment Study
GPC Offers Customer Interconnection
Proposal
Distributed Generation
Interconnection Agreement Executed
Customer pays GPC Interconnection Cost
Upfront
GPC Installs GPC Interconnection Equipment
GPC Conducts Facility Acceptance Testing
GPC Authorizes Parallel Operation
Facility
10 Days +10 Days +10 Days
+45 Days +45 Days +5 Days/+90 Days +10 Days/+30 Days
+10 Days +Construction
+7 Days +3 Days
Up to 155 Days + Construction
Customer Submits Application Package• Facility One‐Line Electrical Diagram• Facility Relay and Metering One‐
Line• Proof of site control in the form of a
property tax bill, a lease agreement or other legally binding contract
• Application for Distributed Interconnection
• Required Technical Data
GPC Interconnection Process
Customer Submits Application Package
GPC Processes & Reviews Application
Package
GPC and Customer Site Visits
GPC Conducts Distribution System
Studies
GPC Conducts Interconnection Equipment Study
GPC Offers Customer Interconnection
Proposal
Distributed Generation
Interconnection Agreement Executed
Customer pays GPC Interconnection Cost
Upfront
GPC Installs GPC Interconnection Equipment
GPC Conducts Facility Acceptance Testing
GPC Authorizes Parallel Operation
Facility
GPC Conducts Distribution Equipment Study
• 15 to 30 Business Days for GPC to conduct and complete DSS of Facilities less than or equal to 2MW after Facility is conceptually finalized by both GPC and Customer.
• 25 to 45 Business Days for GPC to complete DSS of Facilities 2MW to 10 MW after Facility design is conceptually finalized by both GPC and Customer.
Distribution Study Practices (Inverter Based)
• Less than 25kW – Stamp and Go Procedure– Inverter must be UL Standard 1741
• Less than 1MW – Stiffness Factor Procedure– Engineering Guide for Integration of Distributed Storage and
Generation EPRI ID: 1024354– Stiffness Factor = Isc/Idsg
DPV Hosting CapacityCategory Criteria Basis FlagVoltage Overvoltage Normal Voltage (ANSI C84.1) ≥ 1.05 Vpu
Voltage Voltage Deviation
Maximum difference in node voltage from no PV to full PV
≥ 3% at primary≥ 5% at secondary≥ ½ band at regulators
Voltage Unbalance Phase voltage deviation (ANSI C84.1) ≥ 3%
Loading Thermal Element loading ≥ 100% normal rating
Protection Total Fault Contribution
Total fault current contribution at each sectionalizing device ≥ 10% increase
ProtectionForward Flow Fault Contribution
Forward flow fault current contribution at each sectionalizing device
≥ 10% increase
ProtectionSympathetic Breaker Tripping
Breaker zero sequence current due to an upstream fault ≥ 150A
Protection Reduction of Breaker Reach
Deviation in breaker fault current for feeder faults ≥ 10% decrease
Protection Breaker/Fuse Coordination
Fault current increase at fuse relative to breaker current increase ≥ 100A increase
Protection Anti-Islanding Minimum load at each sectionalizing device ≥ 50%
Power Quality
Individual Harmonics
Individual harmonic voltage magnitude ≥ 3%
Power Quality
Total Harmonics Total harmonic voltage distortion ≥ 5%
Control Regulator Increased duty > basecase+1
Control Capacitor Increased duty > basecase+1
CYME Analysis (Inverter Based)
• Voltage Violations – 97% to 105% ANSI C84.1 Primary – 3% Voltage Imbalance
• Overload Conditions• Neutral current
– Total current less than 33% of trip setting
• Simulations– Summer peak load without DG– Summer peak load with DG – Valley at 10:00AM – 2:00PM without DG – Valley at 10:00AM – 2:00PM with DG– Locked automation setting testing
CYME Analysis Assumptions
• Connected Transformer kVA Load Allocation Model– Use historical peak and valley substation loading information
– Locked customer loading for customers > 2MVA– 60% constant impedance & 40% constant power loads
• Electronically Coupled Generator– Kw, pf, Fault Contribution (140% of nameplate)
GPC Interconnection Process
Customer Submits Application Package
GPC Processes & Reviews Application
Package
GPC and Customer Site Visits
GPC Conducts Distribution System
Studies
GPC Conducts Interconnection Equipment Study
GPC Offers Customer Interconnection
Proposal
Distributed Generation
Interconnection Agreement Executed
Customer pays GPC Interconnection Cost
Upfront
GPC Installs GPC Interconnection Equipment
GPC Conducts Facility Acceptance Testing
GPC Authorizes Parallel Operation
Facility
Facility Acceptance Testing• Inverters >250kW• Witness Test
– GPC Witness Test Personnel• Required to record and witness test
– GPC Switching Personnel• Required to operate the disconnecting of the high side fuse or switch
– Customer Setting Engineer• Required to make adjustments to interconnection protection equipment
– Customer Test Engineer• Required to perform secondary injection testing on interconnection protection
equipment
– Customer Systems Operator• Required to perform the customer switching of DC and AC systems
– Inverter Control Engineer• Required to make adjustments to set points of the inverter if needed
– Customer Representative• Required to sign witness test report upon completion
Facility Acceptance Testing• Transient Overvoltage Test
• Single Phase Disconnect Test– Shut down timing – 2 sec disconnect, 5 min reconnect
• Inverter Control Mode Test– Control power factor to
predetermined set point– 30 min
Site Testing Pictures
Normal Peak Voltage = 400 Volt = 1 PU
Maximum Peak reached = 702 Volt = 1.76 PU PASS
Normal Peak Voltage = 400 Volt = 1 PU
Maximum Peak reached = 1100 Volt = 2.75 PU
FAIL
Normal Peak Voltage = 400 Volt = 1 PU
Maximum Peak reached = 1171 Volt = 2.93 PU
Transient Over Voltages last 24 ms
FAIL
Notice the voltage peaks barely goes above 800 Volts or 2 PU
PASS
By Comparison, look at the same inverter installed at another location
Notice the voltage peaks barely goes above 800 Volts or 2 PU
PASS
By Comparison, look at the same inverter installed at another location
Single phase opened here
Single phase closed here
Approximately 7 seconds of open phase
Single Phase Open Voltage Test
After settings on the inverter were changed
The inverter takes 2 seconds before shutting down.
Next Steps
• Interconnection study with multiple connected DG• Winter peak interconnection study?• Need better estimate of time series impact• Need CBA of constant PF inverter control• Need to share learnings from utility experiences• Southern Company needs to develop a DERMS
• Develop strategic plans at all business units for the integration of DER
Questions?
Dexter LewisResearch EngineerResearch and Technology ManagementSouthern Company