Using the State Estimation Tool

The main State Estimation tool is available within Flex Operations. The tool presents two primary tabs:

• Sources: Lists analysis sources that can be enabled, disabled, and solved. Users may run state estimation per source or globally.

• Results: Displays per-measurement estimation results, including measured values, power flow values, estimated values, residuals, differences, and data quality flags.

DSE Sources Tab

This tab is populated from the dse_sources table which could either be a subset of the pf_sources table or the entire pf_sources table.

The Sources table displays the following columns:

• Source Name: Source name.

• Enabled: Whether the source is enabled.

• Update Date: The last update date and time.

• Num Devices: Number of devices in the source.

• Num Measured Devices: Number of devices with measurements.

• Num Measurements: Number of utilized measurements (ignores bad quality and disabled).

• Solution Status: Solution status (for example, Solved, Suspect SCADA, Model error, Failed).

• Bad Measurements: Number of measurements flagged as bad data.

• Num Iterations: Number of solver iterations.

• Solution Time: Solution time in seconds.

• Initial Residual: Initial residual norm. (All of f(V) in What Is State Estimation.)

• Final Residual: Final residual norm.

• Initial Meas Residual: Initial measurement residual. (Contributions to f(V) by measurements alone)

• Final Meas Residual: Final measurement residual

• Residual Delta %: Percent improvement in total residual.

• Meas Residual Delta %: Percent improvement in measurement residual.

• Avg Voltage Change: Average voltage change from power flow. Hidden by default.

• Max Voltage Change: Maximum voltage change from power flow e. Hidden by default.

• P Value: P-value indicator for solution fit. (Higher is better, 1.0 is best)

And has the following available actions:

• Refresh Table: Updates the grid (after running state estimation, this is required as the underlying computation can take a while)

• Enable Source: Enables the set of sources and requests a solution be generated.

• Disable Source: Disables the set of sources (clearing all results for them).

• Run Source: Requests a DSE solution for the set of selected sources.

• Run Global DSE: When no sources selected, you can request all enabled sources to run.

Note: Certain actions in the DSE Results tab can cause the DSE Sources tab to clear its data.

DSE Results Tab

This tab is populated from the dse_results table. This table is dynamically maintained by DSE. Initially it will be empty, as DSE is run it will become populated for those sources. If a source is disabled, the results for that source will be removed entirely.

The Results table displays the following columns:

• Source Name, Substation Name, Feeder Name, Device Name

• Class: Handle class. Hidden by default.

• Index: Handle index. Hidden by default.

• Measurement Type: Measurement type (for example, Amps_A, KW_B, KVAR, KV, Angle).

• Bad Quality: SCADA measurement quality flag. Check for bad quality, empty for good quality.

• Used Measurement: Whether the measurement was used in the estimation.

• Weight: Effective Measurement weight (depends on Rel Error, Abs Error, and Meas Value).

• Relative Error: Relative error percent.

• Absolute Error: Absolute error percent.

• Measured Value: Measured value.

• PF Value: Power flow (initial) value.

• Estimated Value: Estimated value after DSE (Note, unused measurements will report this but they do not factor in the residual calculation).

• Orig % Diff: Percent difference between measured and PF value.

• % Diff: Percent difference between measured and estimated value.

• Bad Data: Bad data flag (checkmark when normalized residual exceeds threshold).

• Normalized Residual: Normalized residual value (this is the residual divided by its computed sensitivity, a value of 1e+10 means that sensitivity was zero, and thus will be automatically marked as bad data).

And has the following available actions:

• Refresh Table: Refreshes table (necessary to see new state estimation results)

• View On Map: Jump to the map view of the selected device (one device only)

• Update Weights: Open the update weights display for the selected devices (pre-populate data from the first selected device).

Update DSE Weight

DSE weights are populated by default values that can be overridden via global settings in the configuration assistant. Any individual measurement can be overridden (the Update DSE Weight display provides an interface for this) via the dse_weights table.

The DSE Weight display allows the user to configure if a specific measurement is enabled/disabled, the relative error, and the absolute error. Because of the complex relationship between weight and the relative/absolute errors (see What Is State Estimation for a definition) we provide an estimation of their values based on current values. The expected weight updates when you click out of the text box. You can then commit your selection or reset to the value you initially entered or leave. If you press commit default it will clear any user overridden value(from the dse_weight) table.

Whenever any weight is updated, we clear all results for that source as they are no longer valid.