1. Distributed Energy Resources (DER) Experiences at CenterPoint Energy
2/23/2015
Distributed Energy Resources (DER) Experiences at CenterPoint Energy
by James Koinis & Aman Fatma
Distribution Planners
Approved by: Ed Briggs, P.E. Manager Distribution Planning
Presented at SWEDE: 05/04/2018
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CenterPoint Energy Proprietary & Confidential Information

2. Legal Disclaimer
This presentation is being provided for informational purposes only and does not purport to be comprehensive. Neither CenterPoint Energy, Inc., together with its subsidiaries and affiliates (the "Company"), nor its employees or representatives, make any representation or warranty (express or implied) relating to this information. By reviewing this presentation, you agree that the Company will not have any liability related to this information or any omissions or misstatements contained herein. You are encouraged to perform your own independent evaluation and analysis.
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3. Agenda Safety Share Historical Utility Operation What is a DER?
Why are DERs connecting to the Utility Grid?
CenterPoint Energy DER Experiences
Distribution Planning
Customer Interaction
Metering and Telemetry
Distribution Protection
References
Questions?
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4. Safety Share
2/23/2015
CenterPoint Energy Proprietary & Confidential Information
CenterPoint Energy Proprietary & Confidential Information

5. Electricity Distribution Background
2/23/2015
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CenterPoint Energy Proprietary & Confidential Information

6. DER- Future of Electric Utility
2/23/2015
What is a DER?
Distributed Energy Resource (DER) is an electrical generating facility located at a Customer's point of delivery (point of common coupling), 10 megawatts (MW) or less, and connected at a voltage less than or equal to 60 kilovolts (kV), which may be connected in parallel operation to the utility system. [1]
Rate of interconnection.
Currently CenterPoint Energy has approximately 261MW of existing DERs connected and expecting 189 MW in the coming year.
Types of DERs.
Renewable
Solar
Wind
Hydro
Landfill Gas
Non-Renewable
Diesel
Natural Gas
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CenterPoint Energy Proprietary & Confidential Information

7. CenterPoint Energy DER Installations
2/23/2015
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CenterPoint Energy Proprietary & Confidential Information

8. CenterPoint Energy Installed DER Types
2/23/2015
Diesel
43.1%, MW
Solar
9%, 23 MW
Landfill Gas
6%, 13 MW
Natural Gas
42.9%, MW
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CenterPoint Energy Proprietary & Confidential Information

9. Why are DERs connecting?
2/23/2015
ERCOT Emergency Response Service (ERS)
Four Coincident Peak (4CP) response
Load Zone-level wholesale price response in the Real-Time Energy Market
Back up Generation
Incentive Programs
CenterPoint Energy Proprietary & Confidential Information
CenterPoint Energy Proprietary & Confidential Information

10. Distribution Planning Customer Interaction Metering and Telemetry
Our DER Experiences
2/23/2015
Distribution Planning
Customer Interaction
Metering and Telemetry
Distribution Protection
CenterPoint Energy Proprietary & Confidential Information
CenterPoint Energy Proprietary & Confidential Information

11. Distribution Planning - DER Modeling
2/23/2015
CYME 7.2/8.0 for DER studies
Features nested views:
Interconnection application with detailed One-Line.
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CenterPoint Energy Proprietary & Confidential Information

12. Distribution Planning - DER Modeling
2/23/2015
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CenterPoint Energy Proprietary & Confidential Information

13. Distribution Planning – Other Concerns
2/23/2015
Split Service Agreements
For example, at the Point of Common Coupling (PCC):
12kV – 4MW pts of 2MW
35kV – 6MW pts of 3MW
(*not an all inclusive list*)
Voltage Concerns
Load Rejection Overvoltage (LRO)
Transient or Temporary Overvoltage (TOV)
DER Customers not wanting to take kVARs
Substation Capacitor Bank
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CenterPoint Energy Proprietary & Confidential Information

14. Substation Capacitor Banks
2/23/2015
Substation Capacitor Banks
Received DER customer complaints of tripping due to high voltage.
Substation Cap Bank was turned on to provide VARs to the transmission section.
DERs that are close to the substation are more prone to high voltage levels causing them to trip.
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CenterPoint Energy Proprietary & Confidential Information

15. DER and Telemetry
2/23/2015
Need more telemetry to allow operators better understanding of the system.
How do you get telemetry?
What is the most economical way to obtain the telemetry?
Who will pay for the equipment necessary to obtain the telemetry from the DER site?
Although DERs are accounted for during Load Forecasting, our large DERs are modeled off because they have not been consistently running during peak load season each year.
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CenterPoint Energy Proprietary & Confidential Information

16.  / Y-grounded to Y-grounded/Y-grounded
2/23/2015
 / Y-grounded to Y-grounded/Y-grounded
Due to potential High Voltage damage to equipment, had to change to Y-grounded/Y-grounded transformer for DERs at customer cost
Additional Expense and Time
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CenterPoint Energy Proprietary & Confidential Information

17. Customer Interaction Exporting kW Importing kVAR 2/23/2015
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CenterPoint Energy Proprietary & Confidential Information

18. Protection Experiences
2/23/2015
Why Transfer Trip (TT)?
Unintentional islanding may lead to several problems in utility grid such as power quality, voltage and frequency stability, interference etc.
How TT affects DERs
Time and Money
Reverse Power Trip
Conditional TT
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CenterPoint Energy Proprietary & Confidential Information

19. Reverse Power Trip Brought about by Customer Request
2/23/2015
Reverse Power Trip
Brought about by Customer Request
Goal is to have anti-islanding at a lower cost and faster processing time than Transfer Trip.
Other Utilities using it in place of Transfer Trip
How do you determine the trip set point?
What are the risks to CNP or customer’s equipment?
We are still in the evaluation phase.
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CenterPoint Energy Proprietary & Confidential Information

20. Conditional Transfer Trip Operation
2/23/2015
Conditional Transfer Trip Operation
Used to not trip critical care facilities unnecessarily.
It was decided that an additional Meter CT would be used to determine if the generator was on or off.
This information could then be used to determine when to trip breaker “A”.
Customer’s Relay
Generators
Meter CT
Main Service G B A
Meter CT
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CenterPoint Energy Proprietary & Confidential Information

21. References
2/23/2015
[1] “Distributed Generation.” ERCOT.com : Web. 18 April <
[2] “Smiley Face Happy Thumbs Up.” Pixabay.com : Web. 18 April <
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CenterPoint Energy Proprietary & Confidential Information

22. Questions?
2/23/2015
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CenterPoint Energy Proprietary & Confidential Information