tdewitte-esristaff

Utility Network for Gas: And the Answer is...

Blog Post created by tdewitte-esristaff Employee on Dec 12, 2017

Using subnetworks for on-demand summarization of information about all or a selected part of your gas system

By Tom Coolidge and Tom DeWitte

 

Regulatory and business stakeholders have been asking summary information questions of gas utility professionals about their systems from the beginning of the gas industry.  Some of these questions are cyclical, such as those required to be answered in annual or periodic report filings.  Others are ad hoc, asked at various times in response to business challenges or opportunities.

 

Even in earlier times of smaller and simpler systems, providing complete and accurate answers often was not easy.  In speaking today with industry colleagues about data issues, I often think back to William Puryear’s comment about the evolution of mapping within the gas engineering department at what now is Baltimore Gas and Electric, America’s first gas utility:

“When the territory served and the mileage of mains was so small that the locations and sizes of all mains were matters of common knowledge, the necessity for accurate and accessible records was probably not apparent, and the result was that for many years no adequate records were kept.  Even after records were started, they were for a long time merely written descriptions of the work done, and in many cases it was considered sufficient to say that a main of a given size was laid on one side or the other of a certain street in some direction from a given point.  In fact, the side of the street on which the main was laid was not always given.” He goes on to describe how they evolved over many years a manual mapping system from there.

 

Let’s consider four points.

One, it is safe to say that quality and consistency of early records, if they were made, varied greatly.  There were no real industry standards, and each utility tailored whatever record system they had to their individual preferences.

 

Two, gas system summary information is dynamic, not static.  When a change is made to the gas system, summary information about the part of the gas system in which the change was made changes too.

 

Three, today’s gas systems in many cases are rollups of multiple predecessor gas systems combined through mergers and acquisitions.  As gas utilities grew in this manner over time, records did or didn’t get passed along and unified.

 

Four, answering summary information questions has long been a manual task.  For instance, information such as the pipe volume of a single pressure or isolation zone has been a manual calculation known mainly to the engineers and system control staff.  Keeping this information current has been problematic, since it changes every time a construction project is completed for the affected zone.  This information historically has not been automatically maintained. Therefore, most engineers have been hesitant to share this information with the rest of the organization out of concern that others will make decisions on potentially out of date information.

 

In short, gas organizations have a long history of struggling to manage, share and maintain summary information about their gas system.  It remains a struggle today.  While recordkeeping systems have advanced substantially, legacy data issues persist, and contemporary data issues continue to arise.  Networks are larger and more complex.  Questions are asked more frequently and are expected to be answered more quickly. The demand by regulatory and business stakeholders on a quicker and more frequent basis for summary information about all or a part of a gas system poses an increasingly steep challenge for gas industry professionals.

 

In this context, the need for an automated solution to answering summary information questions about dynamically changing gas systems is apparent, and now a solution is here in the form of the subnetworks capability of the utility network.  And the answer is…

Technical Discussion

               To address this need, the new utility network for gas by Esri provides the ability to configure an automated summarization of gas system information as part of its subnetwork capabilities.  For end users such as Cathodic Protection department staff, this means they can now view a CP area’s total metallic pipe surface area to aide in determining the correct amperage to set a rectifier too.   It also means that system controllers can easily see the total pipe volume of a pressure zone.  This will help them in determining how much additional gas can be packed into the pressure zone pipes in preparation for a surge in usage demand such as when a strong winter cold front is about to traverse across the service territory.

Summarizing for a Subnetwork

               Each subnetwork tier can have its own unique set of summary attributes.  Summary attributes are user defined fields added to the subnetline feature class to store the desired summarizations. The summarization is limited to only those utility network device, junction, or line feature class features which have been associated to the specific subnetwork feature.

A single summary attribute field can have a different summarization for each unique tier.  You can add as many summary attributes to the subnetline feature class as the underlying enterprise geodatabase relational database (i.e. Oracle, SQL Server, PostgreSQL, etc) can support.

 

What are summary attributes

Summary attributes are user defined fields added to the subnetline.  What makes these fields special is that a summarization method has been defined for this field for a specific tier.  To understand what this means, let’s take a look at how one would summarize the total surface area of only the metallic pipe for a cathodic protection area subnetwork.

The first step is to use the geoprocessing tool, Add Field to add the attribute TOTALSURFACEAREA to the subnetline feature class.  This summary attribute must be of a data type of short integer, long integer, double, or date.

 

The second step is to use the geoprocessing tool, Set Subnetwork Definition to define how this summary attribute is to be populated. The specific summarization used to populate the TOTALSURFACEAREA summary attribute, is to ADD the PIPESURFACEAREA attribute values of each utility network line feature associated to the cathodic protection area subnetwork feature. The utility network supports the following methods of summarization: AVERAGE, COUNT, MAX, MIN, ADD, and SUBTRACT. Only those utility network line segment attributes which have been designated as a network attribute can be used for the summarization.

 

The third step is to use the geoprocessing tool, Set Subnetwork Definition to define the device, junction or line features which will participate in the summarization.  The Set Subnetwork Definition geoprocessing tool will limit the features to be summarized to only metallic pipe segments based on the listing of valid utility network line Asset Group/Asset Type unique value pairs. For our PIPSURFACEAREA summarization for the cathodic protection area tier, the list of valid Asset Group/Asset Type unique value pairs needs to define the metallic pipe segments.

What are network attributes

               A utility network has a property known as network attributes. A network attribute is a value stored in the network topology. For the Cathodic Protection area example we have been describing the network attribute is PIPESURFACEAREA. This utility network property is defined using the geoprocessing tool, Add Network Attribute.

 

Network attributes are required to have a data type of short integer, long integer, double, or date. Network attributes are then associated to a utility network device, junction or line feature class attribute. The association between the utility network, network attribute and a utility network feature class attribute is accomplished with the Set Network Attribute geoprocessing tool. While a network attribute can be associated with only one attribute on a feature class, there is no limit to the number of network attributes a single utility network can have. The feature class attribute to be associated to the network attribute must be of the same data type, but it does not have to have the same attribute name.

When are the summary attributes updated

               Summary attributes are updated only when the geoprocessing tool, Update Subnetwork is run.  This tool can be run by users at the end of their editing workflows.  Additionally, since this is a geoprocessing tool, it is very easy to use standard python scripting batch processing techniques to have this process run as a batch process at a scheduled interval, such as every evening.

Pre-defined summary attributes in UPDM 2017 Edition

               To help simplify the deployment of the utility network, the Utility and Pipeline Data Model (UPDM) 2017 edition will come with the following Summary Attributes pre-configured for the utility network.

Subnetwork Tier

Summary Attribute

Summary Definition

System

TOTALLENGTH

Sum Shape_Length for all zone pipe segments

System

PIPEVOLUME

Sum PIPEVOLUME for all zone pipe segments

Pressure

TOTALLENGTH

Sum Shape_Length for all zone pipe segments

Pressure

PIPEVOLUME

Sum PIPEVOLUME for all pipe zone segments

Pressure

MAOPDESIGN

Find minimum MAOPDESIGN of all zone assets

Pressure

MAOPTEST

Find minimum MAOPTEST of all zone assets

Pressure

MAOPRECORD

Find minimum MAOPRECORD of all zone assets

Isolation

TOTALLENGTH

Sum Shape_Length for all zone pipe segments

Isolation

NUMBERVALVES

Count Devices of AssetType = Critical Valves

Isolation

NUMBERMETERS

Count Devices of AssetType = Customer Meters

Isolation

PIPEVOLUME

Sum PIPEVOLUME for all zone pipe segments

CP Area

PIPESURFACEAREA

Sum the PIPSURFACEAREA for all zone metallic pipe segments

CP Area

TOTALLENGTH

Sum Shape_Length for all zone metallic pipe segments

 

 The utility network subnetwork summary attribute capabilities directly addresses the gas communities long struggle to manage, share and maintain summary information about their gas system. The utility network subnetwork capabilities provide the means to solve the core of this problem, which is the automated creation and maintenance of this summary information. With the management of the summary information automatically maintained by the utility network subnetwork capabilities this information can now be shared throughout the organization with the confidence that it will accurately represent the current state of the gas system.

 

PLEASE NOTE: The postings on this site are my own

and don’t necessarily represent Esri’s position, strategies, or opinions.

Outcomes