Reliability and Asset Management

Reliability and Asset Management

Tony Villocino
Salt River Project
1600 N. Priest Drive
Tempe Arizona 85281

Abstract

The Salt River Project is an established electrical utility in Phoenix, Arizona. The GIS Services group of the SRP developed and implemented a GIS for several work groups to assess the condition and predict failure of various electrical system components. The result was an integrated workflow process and GIS application called RAMS (Reliability and Asset Management System).

Discussion will address developing and implementing GIS to address the following; labor cost, capital resources, outage costs, costs of reducing risk, prioritizing customers, prioritizing equipment replacement and scheduling inspections. RAMS is an evolving, growing, integrated set of applications providing a spatial view of the existing and planned work. RAMS facilitates the inspection of power system components such as wood poles and overhead lines. Using non-destructive strength evaluation and infrared technology in the field, inspection results are captured in the GIS. RAMS also provides predictive analysis and prioritization of cable using several inter-related predictive algorithms. RAMS interfaces with two work order systems, multiple GIS databases, and utilizes an intranet web interface. All of these components together have created a detail work-management strategy that has real world impacts of what gets inspected when, who has already worked on what, and what equipment is going to be replaced before it fails.

Functional Overview

The basic requirement of Reliability Planning Analysis is to prioritize geographic areas for preventive inspections based on a cost benefit model. Cost benefit can be determined per circuit by the represented type of KW load (residential/commercial/critical circuits). The circuit can then be queried for the specific geographic areas it crosses and the density of load points of a type within those areas.

The query is executed through a GIS application. The application requires an extract of customer data containing specifics about customer type and KW load. This customer data is keyed to the Circuit database through the transformer 40-acre codes, producing information about the customers and demand types for individual transformers/circuits. The circuits can be queried for the geographic areas they fall upon and the load types represented by each geographic area. A prioritization can occur for the geographic areas based on the highest priority circuit occupying the area (Wood Pole and PM Line analysis).

Figure 1

The query returns results based on the type of equipment analysis being executed (Wood Pole, PM Line, and Cable Replacement). This is differentiated so that the facilities that are interesting to the specific analysis type can influence prioritization of the geographic areas.

Results of the query are made persistent so the information of a particular analysis can be recalled for later use. An object will be stored in the GIS database capturing the analysis information. The information will be viewable through a standard reporting interface (RAMS Reporting Tool) and the GIS Object Browser.

Architural Overview

SRP’s RAMS application consists of a GIS platform, a work order system and an intranet web based application. The GIS serves as the centerpiece for workflow, it in turn provides all the printed map functionality, analysis capability and data capture components. The work order system is a stand-alone system that is leverage by the GIS using ODBC connectivity. The web application provides an interface to collect data about equipment inspections by equipment inspectors. The web component is an extension of the GIS and interfaces directly with GIS databases and objects.

Scope of the Utility and Service Area In determining the need for the investment in the GIS it is important to outline the magnitude of infrastructure to be maintained by the utility. Below is a summary of the quantities of candidate equipment that is managed by the computer application.

Table 1

Number of transformers	Approximately 123,000
Number of switches	Approximately 22,100
Number of capacitors	Approximately 2,450
Number of feeders	approximately 1,030
Number of substations	approximately 180
Number of poles	Approximately 144,000

RAMS GIS is SRP’s approach to determining the value associated when damage or failure occurs to distribution or transmission structures and their related equipment. The general nature of reactive maintenance puts the utility in the position where a storm can potentially leave thousands of customers without power. The mobilization of dispatches, troubleshooters, line crews, customer service representatives, media representatives, and many others can be normalized by the implementation of a work flow and data capture process which leverage the unique capabilities of a GIS.

Utilizing another perspective, which addresses the availability of limited resources, is how RAMS GIS helps to determine the best use of the limited capital resources. RAMS is an evolving, growing, integrated set of applications providing a spatial view of the existing and planned work; support for the inspection of various power system components such as wood poles, street lights, and other devices routinely inspected using infrared technology. The RAMS system provides predictive analysis and prioritization related to cable failures and associated replacement. Both analysis types either interface to the work management or extract data from customer information services systems.

These tools provide significant improvements to the preventative maintenance process that ultimately improves system reliability.

Wood pole and line Equipment Inspection Prioritization

To minimize the impact of high winds on it’s above ground electrical system, SRP is accelerating its efforts to inspect and maintain its wood poles. Over a period of 10 years, SRP anticipates on spending $22 million to complete a single pass thru of “wood pole inspection” for its transmission and distribution lines. It will inspect, preserve or replace the 130,000 plus poles in its transmission and distribution system. Currently, crews are inspecting about 10,000 poles each year.

RAMS is built on a GIS platform and provides a single spatially enabled application that consolidates and integrates various stand-alone processes. Previously, each department worked essentially in a vacuum, meeting the department’s local needs. Occasionally a conflict would arise between other groups for resources, and the inefficiency of one crew inspecting the same pole another did, becomes frustratingly apparent. Before RAMS there were no means of viewing what the other departments were doing in regards to inspections, prioritization of work, and submittal of work orders. RAMS has effectively provided for consistency in the work order process among various departments, eliminating duplicate inspection efforts, and ensuring that the same piece of equipment has not been assigned to multiple active or proposed work orders.

In the wood pole and line inspection prioritization process, emphasis is placed on inspection cycles that will allow all equipment to be evaluated in a ten years. Therefore predicative analysis is not utilized, rather preventive analysis is performed. This insures the inspection results themselves determine the likelihood of any individual piece of equipment failing. Given that approach, a more simplistic assumption of more kilowatts on a facility equals higher priority for inspections, is utilized. Subsequently, the GIS will maximize the efficiencies of the fieldwork by logistically grouping these activities by mapping quarter sections. In the past an inspector may be physically close to other equipment that a schematic approach did not reveal as candidate equipment to be inspected.

Much of the electric system that serves SRP’s more than 730,000 customers is buried underground. SRP has increased funding to its underground cable replacement program, allotting $100 million over six years to replace damaged cable. Underground electric systems offer many advantages because they eliminate power poles and overhead electric lines in residential areas and therefore they are popular with customers. However, one drawback has always been in the area of repair and replacement. Over time, underground cable will fail for a variety of reasons: moisture, electric load, over-voltage, and physical damage. Until recently, to solve most residential cable problems it required excavation or trenching. This procedure is costly, disrupts landscaping and pavement, and is not popular with customers.

Consequently, SRP has been concentrating on fixing the cable installed in the 70’s, and in selected areas, has an alternative to trenching that involves a process called cable cure.

In the SRP’s service territory, direct buried cable installed in the 1970’s is failing sooner than anticipated. Annual budget for replacing direct buried cable with cable in conduit does not provide for all cable to be replaced before it fails. Therefore, it was necessary to determine where the utility will get the most when rationing which cable to replace?

It was determined that in order to provide the best return in terms of reliability, the GIS would calculate the predictive customer interruption cost for all direct buried primary conductors in the electrical distribution network. The prioritization of cable replacement activity is based on outage cost, failure rate, probability of failure and the return on investment. Extensive research performed by the line maintenance-engineering group of the SRP determined the constructs of these predictive algorithms. ( J. T. Crozier, Power Quality and Reliability Index based on Customer Interruption Costs. IEEE Power Engineering Review, April 1999. )

Menu driven tools developed in the GIS application allow the end user to pre-process the values generated by the predictive algorithms. These values are assigned to a new object, which shadows the object of a “primary conductor”. The primary conductor is represented spatially on screen as a conductor route. The end user then has a reporting tool which allows them to query these results and sort the values as they determine what is appropriate to their analysis.

Work order diriven work flow processes.

Once predicative or preventive prioritization has been performed it is time to put the GIS to work. Using menu driven interfaces the GIS technician, interfaces with a work order system and creates a work order. This “inspection” work order is homogenous to other types of work orders, except its “facility” is the map quarter section itself. The GIS then spatially determines all the candidate equipment that is physically within that quarter section. The GIS creates a relationship between the work order and all equipment. The GIS then identifies all other open work orders in the quarter section allowing the discretion of the GIS technician to pull equipment from the inspection punch list. This coordination of workflow between GIS and work order eliminates the duplication of inspection and other facilities related activities. For example, an inspection does not have to take place on a piece of equipment that is schedule to be replaced. The GIS then automates a mapping process to produce a large-scale printed map for the inspectors to use in the field. The inspector uses this map as he performs his work in the field.

The results of the field inspections (e.g. problems found or not found, type of problem, suggested remedy) are input to the GIS in one or two ways depending on the type of inspection being carried out. For instance, inspection data is recorded on a hand-held device when contract personnel complete a wood pole examination. Data must be uploaded to the GIS via a CSV dump from this device. Whereas, for an infrared inspection work order, inspectors mark field findings on a map product. Data is then entered into the GIS by a custom Web application. Other users of the system may query the data for ‘exceptions’, i.e. inspections where problems were found and some action needs to be taken. These inspections may then be related to one or more maintenance work orders. The exceptions are the by-product of an automated validation process that looks for completeness of data, duplication of data, and mismatched data (data for facilities not related to the work order). As a by-product to these activities, paper maps and field verification process allows a feedback mechanism for GIS data integrity to be checked.

The inspector finally uses a web based tool for entering the inspection results back into the GIS, at which time the GIS technician uses these results to create additional equipment based work orders. This process identifies the problems with equipment in the field, checks the integrity of the GIS data and put the work orders in place the problems fixed. The inspection results also captures activities that may have been performed on the spot by the inspector to fix a problem. The inspector will submit a redlined version of the paper map to mapping technician to correct inside the GIS.

In conclusion, integrated GIS with work order connectivity has been deemed a success with the working groups at Salt River Project.