Network Analysis for Otter Tail Power Presented by Les Jarriel Power Software & Consulting Inc. Support by Bob Endahl (OTP) Dr. Shouming Zhang, Ken Audet, Sam Phillipson (Siemens PTI)

OTP Overview ~127,000 customers miles of transmission ~650 MW generating capacity Operational Model buses substations switches real-time measurements

PNAA (Power Network Analysis Application)PNAA (Power Network Analysis Application) Initially planned as add-on to the existing EMSInitially planned as add-on to the existing EMS Project ConcernsProject Concerns –Low voltage ( kV) network regions with limited telemetry –Costs had increased since original quotation Project Overview

Technical Challenges 1.Pockets of unobservable radial and loop networks 2.Includes unmetered cap banks controlled by voltage 3.Use distribution factors based on energy meters 4.Connects to high voltage network with potential meter errors

An Alternate Approach Standalone PNAA Provides: PSS/E model import (starting point)PSS/E model import (starting point) Fully-integrated one-line displaysFully-integrated one-line displays Single-substation, Map Board and Geographic OverviewSingle-substation, Map Board and Geographic Overview Graphical model editing capabilityGraphical model editing capability User-configurable tabular displaysUser-configurable tabular displays Support for Python scriptingSupport for Python scripting Close interaction between Vendor and CustomerClose interaction between Vendor and Customer

A Unique System Architecture

PNAA System Configuration

Standalone System Implications Separate displays (PNAA vs. SCADA)Separate displays (PNAA vs. SCADA) Separate databaseSeparate database ICCP mappings requiredICCP mappings required –Many going to ISO or RC anyway Separate infrastructure (no delays)Separate infrastructure (no delays) Costs – more options with standaloneCosts – more options with standalone Vendor supportVendor support

Project Steps Start with a comprehensive PSS/E modelStart with a comprehensive PSS/E model Reduce the model sizeReduce the model size –Use 3 rd party tool to equivalence Import the reduced model into PNAAImport the reduced model into PNAA Independently validate the conversionIndependently validate the conversion –Export to PSS/E and compare PF results Simultaneously build one-line displays while adding breaker detail to the modelSimultaneously build one-line displays while adding breaker detail to the model Import ICCP measurement mappings and ‘plug in’ the OPC/ICCP adaptersImport ICCP measurement mappings and ‘plug in’ the OPC/ICCP adapters SE Tuning: start small and build outSE Tuning: start small and build out

PNAA – Features Network Analysis Functions  Topology Analysis  Power Flow  State Estimator  Contingency Analysis (fully supports complex user-defined contingencies and protection schemes) User Interface  Single-substation, geographic overview and full ‘map board’ one-line diagram displays  Custom symbol support with built-in editor  Simultaneous measurements-and-results display  Color-coded and animated flow arrows  Color contouring by flow or voltage violation  Configurable spreadsheet views  1-click toggle between real-time and study modes

Geographic Displays

Map Board Displays

Color Contouring

2-Way Navigation

State Estimator Performance (< 2s for OTP model) Accurately estimates sub-transmission (low voltage) areas with limited telemetry Supports flow measurements on breakers/switches Supports ‘hybrid’ operations/planning model Supports telemetered flow limits Supports direction-dependent flow limits Bad measurement identification Automatic switch status correction Powerful diagnostic/tuning interface Configurable results publication to ICCP Highlights

SE Tuning – Topology Error Detection SCADA: 10 MW → SE: ← 13 MW SCADA: ← 10 MW SE: ← 33 MW

Overcoming the Primary Technical Challenge Unobservable Islands Conventional Approach: Pseudo- Measurement TechnologyConventional Approach: Pseudo- Measurement Technology New Approach: Virtual Real-Time Measurements TechnologyNew Approach: Virtual Real-Time Measurements Technology Automatically identify unobservable islands and corresponding feeder measurementsAutomatically identify unobservable islands and corresponding feeder measurements Apply a new algorithm to sum loads and losses which takes into account larger impedance and MW lossApply a new algorithm to sum loads and losses which takes into account larger impedance and MW loss Take into account the effects of shunts in unobservable islandsTake into account the effects of shunts in unobservable islands

Virtual Real-Time Measurements Technology

Graphical Model Editing Add equipmentAdd equipment –Intuitive connectivity –1-click breaker insert –Copy/Paste equipment Reconnect equipmentReconnect equipment Delete equipmentDelete equipment Edit equipment attributesEdit equipment attributes Synchronize with model changesSynchronize with model changes

Custom Tabular Displays Start with standard default displayStart with standard default display Filter by area, substation, voltage level, device type, etc.Filter by area, substation, voltage level, device type, etc. Hide unwanted columnsHide unwanted columns Edit visible column widthsEdit visible column widths Save view configurationSave view configuration Unlimited number of custom “views”Unlimited number of custom “views” Each saved view is a sub-tabEach saved view is a sub-tab 1-click activation1-click activation Sort by any columnSort by any column

Custom Display Example

Project Issues Robust convergence after initial tuningRobust convergence after initial tuning Customer took ownershipCustomer took ownership –Minimal continued support needed Extended project timelineExtended project timeline –Many software enhancements were included (now part of the base product) Large model footprintLarge model footprint –Bigger than expected (with MISO and Canada)

Project Notes External model updatedExternal model updated –Import large PSS/E model –Use automated Model Merge function to replace the external PNAA is now used for regional training seminarsPNAA is now used for regional training seminars –Includes joint Black Start studies Model sharing with neighborsModel sharing with neighbors –Import/export PSS/E and CIM/XML

Keys to Success Force Dependence on SE (drop other tools)Force Dependence on SE (drop other tools) Improve Operators Interface (high level)Improve Operators Interface (high level) Start Small and Expand (quality over quantity)Start Small and Expand (quality over quantity) Separate Network Apps from SCADA (system, people, process)Separate Network Apps from SCADA (system, people, process)

Questions ?