Distribution Operation Modeling and Analysis (DOMA)

DOMA Narrative

This application is based on a real-time unbalanced distribution power flow for dynamically changing distribution operating conditions. It analyzes the results of the power flow simulations and provides the operator with the summary of this analysis. It further provides other applications with pseudo-measurements for each distribution system element from within substations down to load centers in the secondaries. The model is kept up-to-date by real-time updates of topology, facilities parameters, load, and relevant components of the transmission system.

The Distribution Operation Modeling and Analysis supports three modes of operation:

1. Real-time mode, which reflects present conditions in the power system.

2. Look-ahead mode, which reflects conditions expected in the near future (from one hour to one week ahead)

3. Study mode, which provides the capability of performing the “what if” studies.

The key sub-functions performed by the application are as follows:

Modeling Transmission/Sub-Transmission System Immediately Adjacent to Distribution Circuits

This sub-function provides topology and electrical characteristics of those substation transformers and transmission/sub-transmission portions of the system, where loading and voltage levels significantly depend on the operating conditions of the particular portion of the distribution system. The model also includes substation transformers and transmission/sub-transmission lines with load and voltage limits that should be respected by the application.

Modeling Distribution Circuit Connectivity

This sub-function provides a topological model of distribution circuits, starting from the distribution side of the substation transformer and ending at the equivalent load center on the secondary of each distribution transformer. A topological consistency check is performed every time connectivity changes. The model input comes from SCADA/EMS, Distribution SCADA, from field crews, from DISCO operator, from AM/FM/GIS, WMS, and OMS databases, and engineers.

Data Management Issues between AM/FM/GIS and ADA Distribution Connectivity Database

Standard interfaces between different AM/FM/GIS databases, data converters, and ADA database are not developed yet for practical use. The AM/FM/GIS databases were not designed for real-time operational use. They lack many objects and attributes needed for ADA. The population of the databases is not supported by an interactive consistency check. The existing extractors of data and the converters into ADA databases do not determine all data errors. The ADA applications must conduct additional data consistency checking and data corrections before recommendations and controls are issued. Typically utility do not have established procedures for regular update of the AM/FM/GIS databases by the operation and maintenance personnel. Therefore many changes implemented in the field remain unnoticed by the databases. Synchronization of the field state with the ADA database is a challenge in modern utilities.

Data Management Issues between CIS and AM/FM/GIS and ADA Distribution Connectivity Database

For the ADA applications, the AM/FM/GIS data must be associated with the corresponding customer information data from the CIS database. This data include billing data and description of the customer specifics, such as rate schedule, customer code, meter number, address, etc. The critical information is the billing data. This data is updated based on metering cycles (typically one month) and is not well synchronized. In order to synchronize billing data an automated meter reading system should be implemented. In order to update the ADA databases more frequently, which would increase the resolution of ADA functions to individual distribution transformers and even customers, a high capacity communication system should be introduced to gather the data from hundreds of thousands of meters at the same time. Some of the modern procedures enabled by AMR conflict with the needs of ADA model.An example is the consolidated bills, where the individual load data of distribution transformers located in different sites of the consolidated company becomes unavailable for the external to CIS world.

Modeling Distribution Nodal Loads

This sub-function provides characteristics of real and reactive load connected to secondary side of distribution transformer or to primary distribution circuit in case of primary meter customers. These characteristics are sufficient to estimate kW and kvars at a distribution node at any given time and day and include the load shapes and load-to-voltage sensitivities (for real and reactive power) of various load categories. In real-time mode, the nodal loads are balanced with real-time measurements obtained from corresponding primary circuits. A validity check is applied to real-time measurements. The load model input comes from Distribution SCADA, from CIS supported by AMR and linked with AM/FM/GIS, and weather forecast systems.

Modeling Distribution Circuit Facilities

This sub-function models the following distribution circuit facilities:

1. Overhead and underground line segments

2. Switching devices

3. Substation and distribution transformers, including step-down transformers

4. Station and feeder capacitors and their controllers

5. Feeder series reactors

6. Voltage regulators (single- and three-phase) and their controllers

7. LTC’s and their controllers

8. Distribution generators and synchronous motors

9. Load equivalents for higher frequency models

All facilities should be modeled with sufficient details to support the required accuracy of Distribution Operation Modeling and Analysis application.

Distribution Power Flow

The sub-function models the power flow including the impact of automatically controlled devices (i.e., LTCs, capacitor controllers, voltage regulators), and solves both radial and meshed networks, including those with multiple supply busses (i.e. having Distributed Energy Resources (DER) interconnected to the power system).

Evaluation of Transfer Capacity

This sub-function estimates the available bi-directional transfer capacity for each designated tie switch. The determined transfer capacity is such that the loading of a tie switch does not lead to any voltage or current violations along the interconnected feeders.

Power Quality Analysis

This sub-function performs the power quality analysis by:

1. Comparing (actual) measured and calculated voltages against the limits

2. Determining the portion of time the voltage or imbalance are outside the limits

3. Determining the amount of energy consumed during various voltage deviations and imbalance

4. Recording the time when voltage violations occur

5. Performing modeling of higher harmonics propagation and resonant conditions based on information available from the sources of harmonic distortion

6. Performing modeling of rapid voltage changes based on information available from the sources of voltage distortion

The sub-function provides the ability to estimate the expected voltage quality parameters during the planned changes in connectivity and reactive power compensation.

Loss Analysis

This sub-function bases its analysis on technical losses (e.g., conductor I²R losses, transformer load and no-load losses, and dielectric losses) calculated for different elements of the distribution system (e.g., per feeder or substation transformer). For the defined area, these losses are accumulated for a given time interval (month, quarter, year, etc.). They are further compared with the difference between the energy input (based on measurements) into the defined area and the total of relevant billed kWh (obtained from the database), normalized to the same time interval. The result of the comparison is an estimate of commercial losses (e.g., metering errors and theft).

Fault Analysis

This sub-function calculates three-phase, line-to-line-to-ground and line-to-ground fault currents for each protection zone associated with feeder circuit breakers and field reclosers. The minimum fault current is compared with protection settings while the maximum fault current is compared with interrupting ratings of breakers and reclosers. If the requirements are not met, a message is generated for the operator.

Evaluation of Operating Conditions

This sub-function determines the difference between the existing substation bus voltage and the substation bus voltages limits.

The sub-function also estimates the available dispatchable real and reactive load obtainable via volt/var control. The operator or other applications can use this information for selective load reduction. The sub-function provides aggregated operational parameters for the transmission buses to be used in transmission operation models.

DOMA Steps

The DOMA Steps include:

DOMA Data Conversion
DOMA without Events
DOMA with Events Causing It to Run
DOMA Runs Based on a Schedule
DOMA Used in Study Mode or Look-Ahead Mode

DOMA Data Conversion

#	Event	Name of Process/Activity	Description of Process/Activity	Information Producer	Information Receiver	Name of Info Exchanged	IntelliGrid Architecture Environments
1.1.1	Data conversion and validation	Extraction, conversion & validation	ADA Database Administrator authorizes the Conversion and Validation function to extract, convert, and validate circuit connectivity and distribution transformer loading data. This is referred to as Stage 1 validation.	ADA Database Administrator	Conversion and Validation function	Authorization to start Stage 1 validation	Intra-Control Center Environment
1.1.2		Checking real-time data	The data in the latest download of DMS SCADA data is checked by DOMA function for changes in topology and used to obtain the latest relevant analog data.	DMS SCADA Database	DOMA function	DMS real-time analog, status & TLQ data	Intra-Control Center Environment
1.1.3		Connectivity change	Topology Update function prepares changes in connectivity based on the latest DMS SCADA data for updating ADA database	DOMA function	Topology Update function	Changes in connectivity	Intra-Control Center Environment
1.1.4		ADA database update	Topology Update function updates ADA database	Topology Update function	ADA Database	ADA database update	Intra-Control Center Environment
1.1.5		Extraction, conversion & validation	Conversion and Validation function receives initial (before any corrections) connectivity, billing and facility parameter data.	AM/FM/CIS database	Conversion and Validation function	Initial connectivity, billing and facility parameter data	Intra-Control Center Environment
1.1.6		Issuing initial Stage 1 report	After Conversion and Validation function completes Stage 1 analysis it issues a report with incorrect circuit connectivity and transformer loading	Conversion and Validation function	ADA Database Administrator	Report with incorrect circuit connectivity and transformer loading	Intra-Control Center Environment
1.1.7		Stage 1 corrections	After reviewing the Stage 1 report, the ADA Database Administrator issues an authorization to perform Stage 1 corrections.	ADA Database Administrator	IT technician	Authorization to perform Stage 1 corrections	Intra-Control Center Environment
1.1.8		Stage 1 corrections	AM/FM/CIS database is corrected based on the Stage 1 report after ADA Database Administrator authorized the procedure.	IT technician	AM/FM/CIS database	Stage 1 corrections	Intra-Control Center Environment
1.1.9		Extraction, conversion & validation	Conversion and Validation function receives connectivity, billing and facility parameter data after Stage 1 corrections have been implemented.	AM/FM/CIS database	Conversion and Validation function	Connectivity, billing and facility parameter data after Stage 1	Intra-Control Center Environment
1.1.10		Issuing report requiring no database corrections after Stage 1	After Conversion and Validation function completes Stage 1 analysis it issues a report showing that no further corrections associated with connectivity, billing or facility parameter data are required.	Conversion and Validation function	ADA Database Administrator	Report showing that circuit connectivity and transformer loading require no corrections	Intra-Control Center Environment
1.1.11		Update of ADA Test Database after Stage 1 corrections	After Stage 1 corrections produce a report with no connectivity and transformer loading problems, the Conversion and Validation function updates the ADA Test Database which sets the stage for Stage 2 validation.	Conversion and Validation function	ADA Test Database	Update of ADA Test Database	Intra-Control Center Environment
1.1.12		Load Flow and Load Transfer Analyses	ADA Database Administrator authorizes the Conversion and Validation function to validate facility parameters via load flow and load transfer analyses. This is referred to as Stage 2 validation.	ADA Database Administrator	Conversion and Validation function	Authorization to start Stage 2 validation	Intra-Control Center Environment
1.1.13		Load Flow and Load Transfer Analyses	Conversion and Validation function receives excerpts from ADA Test Database (after they were updated with Stage 1 corrections) to perform Stage 2 analyses.	ADA Test Database	Conversion & Validation function	Excerpts from ADA Test Database after Stage 1 corrections	Intra-Control Center Environment
1.1.14		Load Flow and Load Transfer Analyses	Conversion and Validation function receives latest statuses and measurements from ADA Database (which in turn are updated by DMS SCADA Database) to perform Stage 2 analyses.	ADA Database	Conversion & Validation function	Latest statuses and measurements from ADA Database	Intra-Control Center Environment
1.1.15		Load Flow and Load Transfer Analyses	After performing Stage 2 analyses, Conversion and Validation function issues a report for ADA Database Administrator.	Conversion & Validation function	ADA Database Administrator	Report on unreasonable load and voltage violations, corresponding facility parameters, results of comparative analyses and correction of inconsistencies	Intra-Control Center Environment
1.1.16		Stage 2 corrections	After reviewing the Stage 2 report, the ADA Database Administrator issues an authorization to perform Stage 2 corrections.	ADA Database Administrator	IT technician	Authorization to perform Stage 2 corrections	Intra-Control Center Environment
1.1.17		Stage 2 corrections	AM/FM/CIS database is corrected based on the Stage 2 report after ADA Database Administrator authorized the procedure.	IT technician	AM/FM/CIS database	Stage 2 corrections	Intra-Control Center Environment
1.1.18		Extraction, conversion & validation	Conversion and Validation function receives connectivity, billing and facility parameter data after Stage 2 corrections have been implemented.	AM/FM/CIS database	Conversion and Validation function	Connectivity, billing and facility parameter data after Stage 2	Intra-Control Center Environment
1.1.19		Update of ADA Test Database after Stage 2 corrections	The Conversion and Validation function updates the ADA Test Database.	Conversion and Validation function	ADA Test Database	Update of ADA Test Database	Intra-Control Center Environment
1.1.20		Load Flow and Load Transfer Analyses	Conversion and Validation function receives excerpts from ADA Test Database (after they were updated with Stage 2 corrections) to perform the next round of Stage 2 analyses.	ADA Test Database	Conversion & Validation function	Excerpts from ADA Test Database after Stage 2 corrections	Intra-Control Center Environment
1.1.21		Load Flow and Load Transfer Analyses	Conversion and Validation function receives latest statuses and measurements from ADA Database (which in turn are updated by DMS SCADA Database) to perform the next round of Stage 2 analyses.	ADA Database	Conversion & Validation function	Latest statuses and measurements from ADA Database	Intra-Control Center Environment
1.1.22		Issuing report requiring no database corrections after Stage 2	After Conversion and Validation function completes Stage 2 analysis it issues a report showing that no further corrections associated with unreasonable load and voltage violations, or corresponding facility parameters are required.	Conversion & Validation function	ADA Database Administrator	Report showing that no further corrections associated with unreasonable load and voltage violations, or corresponding facility parameters are required.	Intra-Control Center Environment
1.1.23		Update of ADA Database	After reviewing the Stage 2 report requiring no further corrections, ADA Database Administrator authorizes the update of ADA database.	ADA Database Administrator	IT technician	Authorization to update ADA database	Intra-Control Center Environment
1.1.24		Update of ADA Database	After permission to update ADA database is given, IT technician receives the needed update from ADA Test database.	ADA Test Database	IT technician