ISO NE Experiences with Internal and External Model Impacts on the State Estimator

Transcription

1 1 ISO NE Experiences with Internal and External Model Impacts on the State Estimator Model Impacts Challenges Sriram Ramesh, Tim Murphy, Dave Krueger, Yuan Li, Audrey Newcomb National Harbor, MD 2014 July 31

2 2 Table of Contents NETWORK MODEL Page 3 INTERNAL MODEL Page 4 EXTERNAL MODEL Page 5 EXTERNAL MODEL contd. Page 6 ISO-NE STATE ESTIMATOR Page 7 STATE ESTIMATOR MANAGEMENT Page 8 ACCURACY CLASS Page 9 RTNET SOL. QUAD DISPLAYS Page 10 SAVE ESTIMATES QUAD DISPLAYS Page 11 INITIALIZATION BUTTONS Page 12 LOAD TREE Page 13 ON-CALL CHECK Page 14 STATE ESTIMATOR PERFORMANCE METRICS Page 15 FUTURE CHALLENGES Page 17

3 3 NETWORK MODEL INTERNAL EXTERNAL CONNECTICUT MASSACHUSETTS RHODE ISLAND VERMONT NEW HAMPSHIRE MAINE NEW YORK NEW BRUNSWICK HYDRO QUEBEC

4 4 INTERNAL MODEL Detailed model of 345, 230, 138, 115 kv transmission system. Down to 69 kv in some cases Lower kv buses modeled in detail for generators Good measurement observability with very few unobservable areas Transmission parameters very accurate Separate process for obtaining and validating these parameters like R, X etc.

5 5 EXTERNAL MODEL New Brunswick 138/230/345 kv explicitly modeled Hydro Quebec Ties to New England modeled

6 6 EXTERNAL MODEL contd. New York 345 kv modeled in detail Plans to complete the 230 kv model by /138 kv explicit model up to 2 buses away from ties Equalized model outside of 2 buses from the ties Equivalent NY model being updated : Changes to the NY model after the update will be maintained by the model exchange process NY model will have accurate parameters when the process is complete Less measurement observability

7 7 ISO-NE STATE ESTIMATOR Online Network Sequence consists of: RTNET Once every 3 minutes or on manual request RTCA Once every 6 minutes or on manual request Primary CA Application that allows controller movement (units, transformers, shunts on AVR) RTCAJR After every RTCA run Secondary CA Application allows only unit controller movement Total Run time of about 54s

8 8 STATE ESTIMATOR MANAGEMENT Several tools used to manage inaccuracies that arise from Internal and External models Accuracy Classes Visual Tools o RTNET Solution Quad Displays o Save Estimates Quad Displays o Initialization Buttons Load Tree Control room has the ability to temporarily manage most internal model problems with regard to SE On-Call SME intervention usually required for External model problems that cause Excess Mismatches or Invalids

9 9 STATE ESTIMATOR MANAGEMENT ACCURACY CLASS About 31 accuracy classes in our current system Separate sets of accuracy classes for Internal and External model management Unique accuracy classes Internal and external generators BASE VALUE Tie line measurements Critical transformer and line measurements Phase Shifters BREAK POINT MANUAL STDEV P.U.

10 10 STATE ESTIMATOR MANAGEMENT RTNET SOLUTION QUAD DISPLAYS Displays the various RTNET solution metrics after every SE run Display divided into 4 quadrants SOLUTION MISMATCH BUS MEASUREMENT MISMATCH BUS FLOW MISMATCH SCADA/RTNET MW ANALOG DELTAS Internal Network Quadrants Displays stations in the internal model and stations associated with Tie-lines External Network Quadrants Displays stations in New York, New Brunswick and Hydro Quebec

11 11 STATE ESTIMATOR MANAGEMENT SAVE ESTIMATES QUAD DISPLAYS Displays the various MW/MVAR bus mismatch estimates after every SE run Display divided into 4 quadrants MW LOAD MISMATCH MVAR LOAD MISMATCH MW GENERATION MISMATCH MVAR GENERATION MISMATCH Internal Save Mismatch Estimates Displays mismatch estimates at stations in the internal model and tie lines External Save Mismatch Estimates Displays mismatch estimates at stations in the external model

12 12 STATE ESTIMATOR MANAGEMENT INITIALIZATION BUTTONS Tools that the Control Room uses to manage Mismatches/Invalids Very useful to provide temporary control of the SE before the on-call SME can intervene Some of the buttons are: Warm Initialization Cold Initialization Initialize Topology External Mismatch

13 13 STATE ESTIMATOR MANAGEMENT LOAD TREE Internal Model Load Tree in real-time updated automatically by the SE Load Tree for study applications updated based on historical data Minimal manual intervention required for SE External Model Manually maintained for both Real time and Study applications

14 14 STATE ESTIMATOR MANAGEMENT ON-CALL CHECK Review RTNET, Save Estimates Examine stations with SCADA vs Quad displays RTNET MW/MVAR/kV differences Ensure critical parameters are Monitor phase shifters within tolerance Review stale data e.g. Net Area Bus Mismatch Check stations with anomalous Investigate stations repeatedly equations causing mismatches

15 15 STATE ESTIMATOR PERFORMANCE METRICS 15,000 SE runs per month on an average 99.5% valid solution rate 300,000 SE runs since EMP26 ISONE upgraded to EMP26 in Nov 2012 Less than 10% stations (both Internal and External combined) have anomalous equations Jan 3 rd 2014 Invalid SE solutions due to High Cost

16 16 FUTURE CHALLENGES Enhance External Model Explicitly model and improve our external model Increase observability in the external areas by adding more measurements PMU Integrate PMU measurements into our State Estimator

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