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Network Analysis for Otter Tail Power. Presented by Les Jarriel (l.f.jarriel@ieee.org) Power Software & Consulting Inc. Support by Bob Endahl (OTP) Dr. Shouming Zhang, Ken Audet, Sam Phillipson (Siemens PTI). OTP Overview. ~127,000 customers 5000+ miles of transmission
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Network Analysis for Otter Tail Power Presented by Les Jarriel (l.f.jarriel@ieee.org) Power Software & Consulting Inc. Support by Bob Endahl (OTP) Dr. Shouming Zhang, Ken Audet, Sam Phillipson (Siemens PTI)
OTP Overview ~127,000 customers 5000+ miles of transmission ~650 MW generating capacity Operational Model 2700+ buses 1800+ substations 5000+ switches 6800+ real-time measurements
Project Overview • PNAA (Power Network Analysis Application) • Initially planned as add-on to the existing EMS • Project Concerns • Low voltage (41-115 kV) network regions with limited telemetry • Costs had increased since original quotation
Technical Challenges • Pockets of unobservable radial and loop networks • Includes unmetered cap banks controlled by voltage • Use distribution factors based on energy meters • Connects to high voltage network with potential meter errors
An Alternate Approach Standalone PNAA Provides: • PSS/E model import (starting point) • Fully-integrated one-line displays • Single-substation, Map Board and Geographic Overview • Graphical model editing capability • User-configurable tabular displays • Support for Python scripting • Close interaction between Vendor and Customer
PNAA System Configuration
Standalone System Implications • Separate displays (PNAA vs. SCADA) • Separate database • ICCP mappings required • Many going to ISO or RC anyway • Separate infrastructure (no delays) • Costs – more options with standalone • Vendor support
Project Steps • Start with a comprehensive PSS/E model • Reduce the model size • Use 3rd party tool to equivalence • Import the reduced model into PNAA • Independently validate the conversion • Export to PSS/E and compare PF results • Simultaneously build one-line displays while adding breaker detail to the model • Import ICCP measurement mappings and ‘plug in’ the OPC/ICCP adapters • SE Tuning: start small and build out
PNAA – Features Network Analysis Functions User Interface • Topology Analysis • Power Flow • State Estimator • Contingency Analysis (fully supports complex user-defined contingencies and protection schemes) • 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
State Estimator Highlights • 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
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 Technology • New Approach: Virtual Real-Time Measurements Technology • Automatically identify unobservable islands and corresponding feeder measurements • Apply 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 islands
Graphical Model Editing • Add equipment • Intuitive connectivity • 1-click breaker insert • Copy/Paste equipment • Reconnect equipment • Delete equipment • Edit equipment attributes • Synchronize with model changes
Custom Tabular Displays • Start with standard default display • Filter by area, substation, voltage level, device type, etc. • Hide unwanted columns • Edit visible column widths • Save view configuration • Unlimited number of custom “views” • Each saved view is a sub-tab • 1-click activation • Sort by any column
Project Issues • Robust convergence after initial tuning • Customer took ownership • Minimal continued support needed • Extended project timeline • Many software enhancements were included (now part of the base product) • Large model footprint • Bigger than expected (with MISO and Canada)
Project Notes • External model updated • Import large PSS/E model • Use automated Model Merge function to replace the external • PNAA is now used for regional trainingseminars • Includes joint Black Start studies • Model sharing with neighbors • Import/export PSS/E and CIM/XML
Keys to Success • Force Dependence on SE (drop other tools) • Improve Operators Interface (high level) • Start Small and Expand (quality over quantity) • Separate Network Apps from SCADA (system, people, process)