UC-GR-1

Functions of the State Estimation tool given conventional measurements

1. Description of the Use Case

1.1. Name of the Use Case

Use case identification

IDArea /Domain(s)/Zone(s)Name of the Use Case
UC-GR-1Area: Energy system
Domains: Distribution, DER, Customer Premises
Zones: Station, Operation
Functions of SE tool given conventional measurements

1.2. Version Management

Version management

Version No.DateName of author(s)ChangesApproval status
0.117th June 2020Themistoklis Xygkis, Panagiotis Pediaditis, Stavroula Tzioka, Eleni Daridou, Dimitris StratogiannisInitial creationDraft

1.3. Scope and Objectives of Use Case

ScopeThe scope of the UC is to investigate whether a high quality estimative of the network state will be acquired via the state estimation tool in real-time conditions under various network operating scenarios. The estimated network state will be used as an input to distribution management applications.
Objective(s)*To improve confidence in actual measurement data obtained throughout the network as well as available load forecasts.
*To capture the real-time operational network state.
Related business case(s)add text

Notes:

  • Scope - describes the aims and boundaries of the use case in a short, precise text.
  • Objective(s) - goals of the use case, in form of bullet points and a short headline.
  • Realted business case(s) - optional

1.4. Narrative of Use Case

Short description The UC investigates the capability of the state estimation tool to filter the available measurement data, comprising actual measurements obtained from active metering devices and pseudo-measurements, i.e. data derived from load forecasting or RES scheduling for network observability accomplishment, in order to identify measurements with gross errors (bad data), to suppress measurement errors, to reconcile inconsistent data and, ultimately, to estimate the actual operational network state.

Complete description The DSO operates the distribution network. A measurement set, composed of actual and historical measurement data obtained from the dispersed metering devices (AMR, GIS, SCADA) installed throughout the network, is available for real-time operation purposes. The related measurements refer to power flows and voltage magnitudes at the top of distribution feeders, power injections from distributed generation units, and load pseudo-measurements for aggregated consumer demand at MV/LV transformer level. Given that the network model (topology) is known with a good degree of certainty, the state estimation tool ensures that the network is observable based on the available measurement set and, subsequently, calculates the estimated state vector, that is, the voltage magnitudes and angles of all network buses.

1.5. Key Performance Indicatiors (KPI)

IDNameDescriptionReference to mentioned use case objectives
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1.6. Use case conditions

AssumptionsPrerequisites
The network model (topology) is known with a good degree of certainty, DSO systems (e.g.AMR, GIS, SCADA) being operational

Notes:

  • Assumptions - general presumptions about conditions or system configurations (e.g. customer’s consent required for some steps; simulation of TSO)
  • Prerequisites - specify which requirements have to be met so that the basis scenario use case can be successfully accomplished.

1.7. Further information to the use case for classification/mapping

OPTIONAL - you can leave it blank

Relation to other use cases
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Level of depth
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Prioritisation
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Generic, regional or national relation
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Nature of the use cases
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Further keywords for classification
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Notes:

  • Relation to other use cases - relation to other use cases in the same project or thematic area. Possible relation types are for instance include, extend, invoke, or associate.
  • Level of depth - reflects the degree of specialisation of the use case. Although no common notation is settled, descriptions like high level use case, generic, detailed, or specialised use case are often used.
  • Prioritisation - helps to rate the use cases in a project from very important to nice-to-have with labels like obligatory/mandatory or optional which have to be agreed upon beforehand.
  • Generic, regional or national relation - for the purpose of generalisation if use case is applied to areas where restictions by law or silimiar issues occur.
  • Nature of the use cases - describes the viewpoint and field of attention like technical, political, business/market, test, etc.

1.8. General remarks

General remarks
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Notes: Add any remarks which do not fit in any other category

2. Diagrams of Use Case

Diagram of Use Case

Sequence Diagram of Use Case

3. Technical Details

3.1. Actors

Actor NameActor TypeActor DescriptionFurther information specific to this Use Case
AMRSystemAutomatic Meter Reading system
DMSSystemDistribution Management System
DSOPersonDistribution System Operator, the entity responsible for the safe and secure operation and management of the distribution system; for data management associated with the use of the distribution system; for procurement of flexibility services using optimization algorithms and the DSO Technical Platform.
DSO Data ServerSystemDatabase containing data from AMR, DMS & SCADA
DSOTPSystemDSO Technical Platform
GISSystemGeographical Information System
SCADADeviceSupervisory Control And Data Acquisition system

Notes:

  • Actor Type - Device/ Sytem/ Person

3.2. References

OPTIONAL - you can leave it blank

No.References TypeReferenceStatusImpact on Use CaseOrganistaor / OrganisationLink
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4. Step by Step Analysis of Use Case

4.1. Overview of Scenarios

No.Scenario NamePrimary ActorTriggering EventPre-ConditionPost-Condition
1Attainment of quality state estimation using accurate pseudo-measurements or indicating new measured points.SCADAState estimation accuracy below predefined thresholdState vector with relatively low accuracyHigh-accuracy state vector
2Fulfillment of observability using additional/alternative data to substitute for the missing ones.SCADAInitially missing or inconsistent measurementsUnobservable networkHigh-accuracy state vector

Notes This part describes the possible scenarios of the use case. The scenarios should comply with the sequence diagrams in Sect. 2 of the template, so that every step describes one part of a communication or action. Apart from a normal success scenario, different failure scenarios or alternatives can be included to describe situations where preconditions are not satisfied or unwanted states are attained.

  • Primary Actor - the first actor appearing in the scenario at the incident causing the scenario to begin.
  • Triggering Event - the incident causing the scenario to begin.
  • Pre-Condition - indicates which terms have to be fulfilled for the scenario to be executed.
  • Post-Condition - indicates which terms should be valid after the scenario. TIt can also specify whether a scenario has been successfully completed or not.

4.2. Steps – Scenarios

Scenario Name: No. 1 - Attainment of quality state estimation

Step No.Event.Name of Process/ ActivityDescription of Process/ Activity.ServiceInformation Producer (Actor)Information Receiver (Actor)Information ExchangedRequirements, R-ID
1Measurements from the Distribution NetworkData AquisitionVarious field measurements that reflect the network state are communicatedREPORTSCADA,DMS,GIS,AMRDSO Data ServerI-01
2Measurements from the Distribution NetworkData AquisitionVarious field measurements that reflect the network state are communicatedREPORTDSO Data ServerBAPI-01
3Measurements from the Distribution NetworkData VerificationAll data received gets verified and secured via blockchain technologyEXECUTEBAPBAP
4Measurements from the Distribution NetworkData AcquisitionVerified and secured data is delivered to the DSOTPREPORTBAPDSOTPI-03
5Measurements from the Distribution NetworkObservability assessmentA numerical observability method is used in order to determine observability statusEXECUTEDSOTPI-03
6Measurements from the Distribution NetworkCalculation of state vectorState estimation algorithm is carried outEXECUTEDSOTPDSOTPI-02
7State vector with low accuracyData AquisitionNew measurements/pseudo-measurements integrated in the State Estimation toolCHANGEDSO Data ServerDSOTPI-01
8Measurements from the Distribution NetworkCalculation of state vectorState estimation algorithm is carried outEXECUTEDSOTPDSOTPI-02
9Measurements from the Distribution NetworkOutput of State Estimation toolEstimated state vector is communicatedREPORTDSOTPDSOI-02

Scenario Name: No. 2 - Fulfillment of observability

Step No.Event.Name of Process/ ActivityDescription of Process/ Activity.ServiceInformation Producer (Actor)Information Receiver (Actor)Information Exchanged (IDs)Requirements, R-ID
1Measurements from the Distribution NetworkData AquisitionVarious field measurements that reflect the network state are communicatedREPORTSCADA,DMS,GIS,AMRDSO Data ServerI-01
2Measurements from the Distribution NetworkData AquisitionVarious field measurements that reflect the network state are communicatedREPORTDSO Data ServerBAPI-01
3Measurements from the Distribution NetworkData VerificationAll data received gets verified and secured via blockchain technologyEXECUTEBAPBAP
4Measurements from the Distribution NetworkData AcquisitionVerified and secured data is delivered to the DSOTPREPORTBAPDSOTPI-03
5Measurements from the Distribution NetworkObservability assessmentA numerical observability method is used in order to determine observability statusEXECUTEDSOTPI-03
6Lack of observabilityData acquisitionAdditional/alternative data to substitute for missing or inconsistent measurements, are integrated in the State Estimation toolCHANGEDSO Data ServerDSOTPI-01
7Measurements from the Distribution NetworkObservability assessmentA numerical observability method is used in order to determine observability statusEXECUTEDSOTPI-03
8Measurements from the Distribution NetworkOutput of State Estimation toolEstimated state vector is communicatedREPORTDSOTPDSOI-02

Notes This part describes the possible scenarios of the use case. The scenarios should comply with the sequence diagrams in Sect. 2 of the template, so that every step describes one part of a communication or action. Apart from a normal success scenario, different failure scenarios or alternatives can be included to describe situations where preconditions are not satisfied or unwanted states are attained.

  • Event - Event triggering a step, specific for that use case.
  • Name of Process/ Activity - general classification of process/activity (e.g. data aquisition).
  • Description of Process/ Activity - more detailed description of the step.
  • Service - addresses the nature of the information flow. Possible: GET (The information receiver obtains information from the information producer after an implicit request.), CREATE (The information producer creates an information object.), CHANGE (The information producer performs an update of the information at the information receiver’s.), DELETE (The information producer deletes information of the receiver.), CANCEL/CLOSE (A process is terminated.), EXECUTE (An action or service is performed.), REPORT (The information producer supplies information of its own account.), TIMER (The actor which represents both information producer and receiver has to enforce a waiting period.), REPEAT (A number of steps has to be repeated until a break condition (stated in the field Event) is satisfied. The contemplated steps have to be added in parentheses.).
  • Information Producer and Receiver (Actor) - actors from actor list in section 3.1
  • Information exchanged (IDs) - ID of the information defined further in section 5

5. Information Exchanged

Information exchanged IDName of InformationDescription of Information ExchangedProtocol
I-01MeasurementsMeasurements from the Distribution Network (voltage magnitudes, active and reactive power injections/flows)TCP/IP, IP over GPRS
I-02State VectorVoltage magnitudes and angles of all network buses
I-03Observability statusThe result of the observability assessment of the Distribution Network, i.e.whether the state estimation problem can be resolved or not

Notes

  • Information exchanged ID - unique number (I-01,I-02…) for identification
  • Requirements to information data - optional, defined in section 6

6. Requirements (optional)

7. Common Terms and Definitions

TermDefinition
Pseudo-measurementAn injection whose value is obtained either from bus load forecasts or generation schedules. It is used as a substitute for a missing measurement in order to restore observability.
State vectorVoltage magnitudes and angles of all network buses

8. Custom Information (optional)

KeyValueRefers to Section