State Estimation (SE) Tuning Guide

Document: s4850002_se_tuning.doc (Release 2003, Rev. A) Proprietary: {OCO} Inc. Status: Tuning in Progress

Introduction & Tuning Phases

SE tuning is an iterative process to bring up the State Estimation function with real-time data. The process is broken down into three main phases:

Phase 1: Initial Bring-up

Bring up SE with the latest database. Tune gross error detection. On-the-job training for customer personnel.

Phase 2: Systematic Tuning

Conducted by the Customer. Systematic tuning of all SE control parameters for all possible power system conditions. Allocation files are smoothed.

Phase 3: System-wide Checkout

Conducted by {OCO}. System-wide checkout of interfaces between SE and other power applications (DLF, CA, etc.).

Pre-Tuning Checklist

Source Data (SDBGEN) processed without errors.
One-line and application displays translated.
Sufficient RTUs are operational for observability.
System cutover complete: Data acquisition is scanning.

Refer to Sections 1.1 - 1.3 of the source document.

Global Tuning Parameters

These parameters control the core SE functions: pre-processing, solution convergence, and gross error detection.

Pre-Processing (RTDBIF, BDPROC) - Ref: APANMC, AMFLTM

MEMPYS (Error Multiplier for Load Change)

Multiplied by AERROR to detect significant load changes. (Doc: 3.2.3)

MXSCYC (Required Steady-State Cycles)

Number of cycles without a load change to declare steady-state. (Doc: 3.2.5)

AMSCT (Out-of-Service Error Multiplier)

For out-of-service equip, measurement must be < AMSCT * AERROR to be considered zero. (Doc: 4.2)

ALSCNT (In-Service Error Multiplier)

For in-service equipment, to detect if flow is significantly zero. (Doc: 4.2)

Solution Convergence (SDSOLN) - Ref: APSESC

PTOL (Internal MW Tolerance)

QTOL (Internal MVAR Tolerance)

ITRLIM (Max Iterations)

DVLIM (Voltage Magnitude Change)

Gross Error Detection (SDGMDA) - Ref: APSESC

CHITE (Chi-Square Threshold Factor)

TCHEK (Student T Threshold)

NSIGMA (Reactivation Deadband)

Troubleshooting Guide for SE Alarm Messages

Select an alarm category or search for a specific message.

SE NOT RUN: NO STEADY STATE
Cause: RTDBIF could not find a steady-state set of A/D measurements within MXECYC cycles. Tune MEMPYS, MXSCYC, or individual AERROR.
RTDB FETCH FOR A/D IN ERR: n
Cause: Error fetching data from RTDB. Check RTU, point definition, and communication links.

IN-SERVICE EQUIPMENT [name] HAS [value] MW FLOW
Cause: Equipment is in-service but flow is near zero. Check status (SSP), measurement error (AERROR), or ALSCNT multiplier.
OUT-OF-SERVICE BUS [name] HAS [value] KV
Cause: Bus is out-of-service but has voltage. Check breaker statuses or adjust AMSCT multiplier.
CIRCUIT [name] LOSS [value] MW > LIMIT [value]
Cause: MW loss > PDELTA. Check terminal measurements or increase the reasonability limit PDELTA.

GROSS MEAS ERR DETECTED : [type]
A measurement has been rejected. Check the measurement and its associated equipment. May require tuning measurement error (SIGMA).
SE EXCEEDED ITERATION LIM : [n] : [p]
Solution did not converge. Check the bus with largest mismatch (B_SEBUSMIS). Consider adjusting PTOL, QTOL, or ITRLIM.

SE Tuning Displays (Appendix B)

These are the primary displays referenced in the guide for viewing and modifying tuning data.

Display ID	Display Name	Description / Key Parameters
B_RTDATA	Analog Measurement Data	AERROR (Measurement Error), ALPHA, IMTYPE (Measurement Type)
B_SEPREP	SE Tuning for Pre-processing	MEMPYS, MXSCYC, AMSCT, ALSCNT, BRFAC, BDFAC
B_SESOLN	SE Tuning for Solution Convergence	PTOL, QTOL, ITRLIM, DVLIM, TAPFLG, BIGDOR
B_SEGROS	SE Tuning for Gross Error Detection	CHITE, TCHEK, NSIGMA, REDNTH, DORMAN
B_SEEBIG	Bus Injection Generation Point Parameters	PMEAS, QMEAS, BGPGME (SIGMA P), BGQGME (SIGMA Q)
B_SECIRM	Circuit Measurement Sigma	FCPMER (From MW Sigma), FCQMER (From MVAR Sigma)
B_SELFBR	Load Flow Bus Measurement Sigma	BKVMER (Voltage Sigma), BPGMER (Generation MW Sigma)
B_SEBUSMIS	Bus Injection Mismatch Summary	Displays buses with largest MW/MVAR mismatches for debugging divergence.

Step-by-Step Tuning Process

Based on Section 1.4 (State Estimation Tuning Steps) and Section 7 (Adjustment for Solution Convergence).

Step 1: Confidence Test

Initial

Execute SE with simulated data from a load flow solution to ensure programs and database are integrated correctly.

Step 2: Review Standard Deviations (SIGMA)

Database Check

Ensure reliable measurements (gen MW) have small SIGMA. Pseudo measurements should have larger SIGMA. (Ref: B_RTDATA)

Step 3: Isolate External Areas

Initial Execution

Disable use of external telemetered values and voltage regulation to prevent corruption from external model errors.

Step 4: Run SE & Check Preprocessor Alarms

Fix Obvious Errors

Execute SE and check alarms from BDPROC (e.g., energized equip with zero flow). Fix RTU/database issues. (Ref: Troubleshooting Tab)

Step 5: Increase Tolerances for Initial Solution

Get First Solution

Increase PTOL, QTOL, CHITE, and measurement error multipliers to help SE obtain an initial, albeit rough, solution. (Ref: Global Params Tab)

Step 6: Analyze Bad Data

Iterative Improvement

Check the Bad Data Summary. Starting with the largest residual, investigate and fix meter definitions, topology, and model parameters.

Step 7: Reduce Tolerances & Repeat