DEW-ISM Implementation at PEPCO: A Model and Data Driven Approach to Automating PV Interconnection Studies

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1 1 DEW-ISM Implementation at PEPCO: A Model and Data Driven Approach to Automating PV Interconnection Studies July 20, 2017 Jason Bank Electrical Distribution Design Inc. (EDD) jason-bank@edd-us.com

2 2 EDD & DEW/ISM Electrical Distribution Design (EDD) Software company founded in early 90s providing software tools to electric utilities Distributed Engineering Workstation (DEW) quasi-static time series power flow solver for transmission and distribution planning, protection, DER/PV analysis, etc. Integrated System Model (ISM) a centralized utility system model designed to support all of the necessary business functions and engineering analysis from a unified set of software tools and databases

3 3 ISM Drivers Traditionally the separate business functions at a utility are split into a variety of groups with each maintaining their own system models, databases and software tools : GIS, Billing, OMS & DMS, Transmission Planning, Distribution Planning, Protection, Secondary system design Analysis tasks spanning multiple business functions often leads to problems interfacing different data sets and software tools Objective of the Integrated System Model (ISM) architecture is to put together one validated well maintain model of the entire utility system which can support all of these functions The ISM architecture reduces overhead related to data validation and model clean up, allows for crosscutting analysis tasks and enables automation of analysis

4 4 Existing ISM Installations Pepco Holdings Inc. Orange & Rockland Utilities National Information Solutions Co-op Silicon Valley Power Central Hudson Gas & Electric Subsidiary of Exelon 1.9M meters 60K Distribution PV sites 8760 load measurements from AMI Subsidiary of ConEd 300K meters in NY IT co-op serving 450 member co-op utilities 4M meters in total Cloud Based Deployment City of Santa Clara, CA 65K meters Subsidiary of Fortis 300K meters in NY Model includes distribution, secondary, network secondary, substations, transmission in progress. Weekly topology updates from GIS. Automated DER Interconnections and Hosting Capacity. Automated BI and Engineering analysis TLM, feeder voltage control, design T, S, D model. Daily updates from GIS. Pilot with switching updates. DEW/ISM provides schematics to GIS. Automated DER Hosting Capacity, DER Interconnections, planning DEW/ISM deployed as desktop and cloud-based Business Intelligence solution at 30 co-op utilities, adding about 2/month with target of 250. Daily updates from GIS and MDMS. Integrated to OMS as well. T, S, D model. EDD provides model updates, moving to daily. Simulation of Phase-Shifting-Transformer operation; Levi Stadium T, S, D model. Moving to daily updates. New project will automate DER Interconnections and Hosting Capacity.

5 5 Pepco Holdings Inc. (PHI) Subsidiary of Exelon Service territory of 8,340 square miles 5.4M people served PHI includes three subsidiary utility companies: Atlantic City Electric: 547K electric customers Delmarva Power: 515K electric customers 130K natural gas customers Potomac Electric Power Company (PEPCo): 842K electric customers

6 6 ISM Implementation at PHI Utility Data Sources GIS OMS/DMS Switch States Controller Settings Data Processing Services Component Manager Data Mapper & Builder ISM Databases DEW Parts Database Primary Circuit Server Secondary Circuit Server Component Settings Database Interface Layers Circuit Downloader Settings Interface DEW Users Engineers (DEW GUI) Automated Analysis SCADA AMI Billing Systems PV & DER Records Load/Gen Database Measurement Interfaces BI Reports (Browser) TLM Feeder Loading Fuse Loading Data Error Reports

7 7 Data Mapper/Builder Maps GIS components to a standard parts database containing all of the part information used by PHI in the field Builds the primary and secondary models from GIS on a weekly basis By enforcing connectivity in the ISM model common GIS errors are automatically identified Connectivity Phasing & Grounding Missing or Erroneous Power Ratings, Voltage Ratings, etc. Mixing Voltage levels without a transformer Loops in radial systems Unpowered components Generates GIS error reports so that corrections can be implemented in the source GIS databases

8 8 Primary Circuit Server Central storage location for all of the primary system models Transmission, substations and distribution in one combined 3- Phase model Models down to the distribution transformer and a lumped load bus attached to the secondary side Users and automated analysis applications can retrieve any desired subset of the model for analysis Full primary model has about 2.4M components PHI Primary Circuit Server model with all 2248 distribution Feeders (transmission not pictured)

9 9 Secondary Circuit Server Central storage location for all of the secondary system models Models include the distribution transformer, secondary conductors and each customer meter Users and automated analysis applications can retrieve any desired number of secondary models an attach them to the primary system model(s), replacing the lumped load buses Secondary models can also be analyzed individually, i.e. secondary system voltage studies Includes secondary models for about 356K distribution transformers (90% of system) Secondary model has about 3.9M components PHI secondary models (Underground in brown, Overhead in black)

10 10 Load/Gen Database Centrally located database from which users and automated analysis applications can download load and generation measurement data 3 years of hourly AMI & MV90 data for 1.3M meters (~24B database rows) Estimated hourly load data is generated from customer class curves and monthly billing data for the 600K customers without AMI Mapping tables relating each customer to their load location, transformer and feeder Contains PV component settings tables which house settings for all 60K PV systems installed on PHI distribution system Connected to Clean Power Research (CPR) data sources to generate estimated PV production for any PV site at any time of the year Estimated PV production is automatically added back to net metered AMI locations so that engineers can download native load for analysis purposes Automatically updates monthly from all of the necessary utility data sources (GIS, AMI, Billing, DMS, SCADA)

11 11 PV Component Settings Table within Load/Gen Database housing settings for all PV sites in PEPCO s service territory Includes records for over 60K PV sites ranging from 0.1kW to 5.5MW with dozens more being added daily Contains site specific details for every PV system Associated customer meter (for removing DG production from net metering) Inverter make and model Inverter Ratings (AC) PV Array Ratings (DC) Location (lat/long, State Plane and location on model) Array tilt angle and orientation Status (Active, Pending, Approved, In Review, etc) Inverter control settings (Volt-Var, Volt-Watt, Fixed Power Factor, etc.) Updated daily based on the results of PV interconnection study reviews and customer applications All the PV sites for a model can be retrieved from the database and attached at the appropriate locations

12 12 Automated PV Evaluation Service Service which runs continuously on a server at PEPCO When a PV application is ready for engineering evaluation it automatically downloads the feeder model and all load data from the ISM and performs a full interconnection study Every PV application is evaluated (regardless of size) and a report is prepared for the reviewing engineers All engineering studies are generally completed within 5 minutes once the application has been flagged for evaluation The service is currently in the final stages of testing at PEPCO and is targeted for deployment at ORU and CHGE by October 2017

13 13 Process Overview PV applications are submitted through PEPCO s online customer work request portal Once an application is ready for engineering evaluation it is identified for review by the Automated PV Evaluation Service The applicant s feeder model and local secondary model are downloaded from the circuit servers All preexisting PV sites, preceding PV sites in the application queue, AMI load data and Clear Sky PV output estimates are attached to the model A full set of engineering studies are automatically executed to evaluate the new PV Application

14 14 Restricted Feeder Screen PEPCO maintains a list of restricted feeders, each feeder has an associated size limit for new PV sites The Automated PV Evaluation Service checks for the applicant s feeder on this list and checks the size of the application against the size limit If the application exceeds the feeder restriction size limit it fails this screen and is flagged for further review by an engineer If the applicant s feeder does not exist on the restricted list or if it is below the size limit it passes this screen

15 15 Protection Study The fault current is calculated at each PV site on the applicant s feeder, with the generation on and off If the application PV site will cause an increase in fault current of more than 10% it fails this study and is flagged for further review by a protection engineer If the fault current increase due to the application PV is less that 10% it passes this study If the application PV site is less than 25 kw this study is skipped (treated as a pass)

16 16 Transformer Overload Study An 8760 time search is performed on the AMI load data and the Clear Sky PV output data in order to identify the critical time points: Time of Maximum Transformer Native Load Time of Maximum PV Output on Transformer Time when PV/Load ratio is maximized on Transformer A power flow solution is calculated at each of these critical analysis times If the applicant s transformer experiences an overload at any of these time points the application fails this study and is flagged for further review by an engineer

17 17 Secondary Violations Study An 8760 time search is performed in order to identify the following critical time points: Time of maximum PV output on feeder Time when PV/Load ratio is maximized on feeder Time of maximum PV output on transformer Time when PV/Load ratio is maximized on transformer A power flow solution is calculated at each of these critical analysis times If the proposed PV site causes a steady state over voltage, overload, or a reverse flow on a network protector anywhere on the local secondary system it is flagged for further review by an engineer

18 18 Primary Violations Study A 100% to 20% PV output step test on all PV within 3000 ft of the proposed PV site is executed for each critical analysis time The application fails this study and is flagged for further review by an engineer if any of the following violations are identified Overvoltages or Undervoltages Overload on any component Feeder, Protection Device or Voltage Regulator Reverse Flows Voltage change at Vreg or Cap greater than 0.5*BW in response to PV step (controller movement) Voltage change in excess of GE Flicker Curve If an application fails this study it will automatically be revaluated with the inverter in fixed power factor control. This reevaluation will not cause the application to pass but the results are presented to the reviewing engineer to help design mitigation

19 19 Queue Handling Considerations Each PV Application is evaluated in the order in which it was it was submitted by the customer All preceding PV sites are included in the feeder model used for evaluation An application which fails the Transformer Capacity or Secondary Violations Study will start a queue for its local transformer, causing all subsequent applications to automatically fail An application which fails the Protection Violations or Primary Violations Study will start a queue for its feeder, causing all subsequent applications to automatically fail Either type of queue is cleared by implementing the required mitigations and updating GIS to match (the model will be rebuilt automatically) After these changes have been made the status of the queued applications is reset. At this point the Automated PV Evaluation Service will begin reevaluating them in order

20 20 Results and Reporting Once the review of an application is complete the results are written to a database were they are accessible to engineering staff at PEPCO Additionally a copy of the model used for the analysis is saved to a server along with a detailed report covering all of the results An application can either be approved or flagged for further review by the Automated PV Evaluation service If it is approved the application is updated accordingly and moves to the next stage of the application process, the details of the proposed PV site are added to the Load/Gen database tagged as pending If an application is flagged for further review it will then be evaluated by an engineer who will design the necessary mitigation

21 21 Other Automated Analysis The Automated PV evaluation Service is only one of a suite of tools in the DEW-ISM and Business Intelligence architecture at PEPCO Examples of other engineering functions that have been automated (over 40 are operational): GIS Error Reports SCADA Measurement Error Reports AMI Measurement/Mapping Error Reports Feeder Peak Load Identification Feeder Peak Shifting due to PV generation Feeder Performance and Efficiency Transformer Load Management Fuse Loading Planning Forecasts PV Hosting Capacity DER Feeder Screening These analysis task are run periodically with results stored to database and accessible via an internal website