1 A Broadband Wide Area Network as an Enabler of Improved Power System Maintenance L. Nordström, Student Member, IEEE, and G. N. Ericsson, Member, IEEE1 Abstract– Wide Area Networks are being deployed worldwide tions with a broadband utility WAN as an enabler for im- at power utilities. By replacing vintage narrowband solutions, proved maintenance. broadband communications can now be used for an entire utility The paper starts in Section II with a classification of data enterprise. One new possibility that has opened up is to improve communication, based on . In Section III, a brief introduc- power system maintenance. During the last ten years, the benefits of adequate asset management have become increasingly clear in tion to some key maintenance concepts is given. In the power industry, due to the economic pressures and the aging Section IV, the paper continues with an analysis of the areas infrastructure. of improvement, in which IT-systems used in conjunction An apparent tool to improve the asset management strategies with efficient broadband communication could improve power is the implementation of IT-systems that support the operational system maintenance. The paper ends with concluding remarks processes. The impact of these systems can be further enhanced and suggested further research works in Section V. by efficient communications allowing the proliferation of func- tionality and data access. B. Survey on IT-support for Power System Maintenance This paper describes the initial stages in analyzing the com- The input to the research regarding IT-systems for Power bined effects of enhanced communication and maintenance re- quirements. It provides a useful maintenance categorization, system Maintenance stems from a survey that was conducted based on empirical data. Also, areas of improvement for power during the fall of 2003 in Sweden. The layout of the survey as system maintenance are elucidated together with the benefit of well as its results has been reported on in . The survey in- enhanced communications. cluded nine power distribution utilities, one hydropower com- pany, and two pulp and paper mills. The basic idea behind the Index Terms—Asset management, Broadband communica- survey was to get an indication if there are differences in use tion, Communication, Power System Control, Power System of IT-support for asset management within different Maintenance, SCADA system, Wide Area Network. industries. Such differences could include the level of IT use, integration of IT systems and overlap of functions. Secondly I. INTRODUCTION the purpose of the study was to investigate where the utilities were focusing their efforts to implement IT support for asset T HIS paper studies the interdependencies in development of two critical areas within Power Systems Engineering, namely that of Power System Communication, see  and , management. and Power System Maintenance, see , , and . The II. CLASSIFICATION OF DATA COMMUNICATIONS paper is based on two parallel efforts in these areas. Within Communication is and will increasingly be a necessary tool Power system communications, the emergence of Broadband for the operation and maintenance of the power network, as Wide Area (WAN) communication is enabling new operation well as for administrative purposes. Technically speaking, and control as well as maintenance processes; see  and . from being a limiting factor, the increasing communication Power System Maintenance is at the same time undergoing capacity now provides possibilities for operating and main- development as the industry is striving for improved cost-per- taining the power network and related businesses in different formance under re-regulation as well as optimization of life- and more efficient ways. At the introduction of fiber optic so- time of installed equipment; see  or . lutions, the narrow-band solutions (range of 100 bit/s) are be- A. Purpose, Outline of the paper ing replaced by broadband communication highways (range of 100 Mbit/s). Hence, a factor of 106 in difference. Such high- The purpose of this paper is to present new opportunities ways make it possible to build a Wide Area Network (WAN), that appear when developments in the areas of power system providing high capacity facilities to/from office sites and sub- communications and power system maintenance are studied in stations. conjunction. The main focus here is to elucidate the implica- But the new possibilities must be utilized in a structured 1 and effective way. Focus should to a greater extent be on ana- L. Nordström is with Industrial Information and Control Systems, Department of Electrical Engineering, KTH – Royal Inst of Technology, lyzing communication needs and requirements, providing a 10044 Stockholm, SWEDEN (e-mail: email@example.com). basis for a technical design. Such analyses have been G. N. Ericsson is with Svenska Kraftnät (Swedish National Grid), deployed at the Swedish National Grid. The different needs P.O. Box 526, 16215 Vällingby, Sweden (e-mail: firstname.lastname@example.org). and requirements have been classified into three different 2 main categories, reflecting the degree of importance of various The communication is characterized by that interaction communication needs : does not need to take place in real time. The time requirements • Real-Time Operational communication requirements are moderate. • Administrative Operational communication requirements In addition to maintenance related communication, this • Administrative communication requirements class contains, the following types of communication: • Maintenance Data A. Real-Time Operational communication requirements • Fault localization Real-time operational communication encompasses com- • Metering and transfer of settlement information munication in real time that is required to maintain operation • Security system of the power system. The class is in turn divided into real-time • Substation camera supervision operational data communication and real-time operational speech communication. C. Administrative communication requirements Administrative communication includes voice communica- Real-time operational data communication encompasses: tion and facsimile within the company (also between the of- • Teleprotection fices that are at different geographical locations) as well as • Power System Control to/from the company, where the communication has an ad- The communication is characterized by the fact that inter- ministrative purpose. action must take place in real time, with hard time require- ments. The communication requirements define the design of III. POWER SYSTEM MAINTENANCE the technical solutions. For teleprotection purposes, messages should be A. General Background transmitted within a very short time frame. Maximum allowed The task of maintaining a complex industrial system, such time is in the range of 12-20 ms, depending on the type of as a power grid, requires some form of systematic approach. protection scheme. The requirement has its origin in the fact In real life, as well as in theory, a number of such approaches that fault current disconnection shall function within are apparent. For example, the European Standard EN approximately 100 ms. 13306:2001  describes maintenance as illustrated in Power System Control mainly includes supervisory control Figure 1. of the power process on secondary or higher levels. These systems are of the kind SCADA/EMS (Supervisory Control Maintenance And Data Acquisition/Energy Management System). Measured values must not be older than 15 seconds, when arriving at the control center. Breaker information shall arrive Preventive Corrective no later than 2 seconds after the event has occurred. Maintenance Maintenance Real-time operational voice communication encompasses traditional telephony; where voice communication has an op- erational purpose, e.g., trouble shooting in a disturbed power Condition Based Predetermined Deferred Immediate Maintenance Maintenance Maintenance Maintenance operational case, power system island operations. The actual possibility of having voice communication is, by the control center staff, considered as one of the most important tools, Figure 1. Breakdown of Maintenance into different types, dependent on when both in normal and abnormal operation cases. Real-time op- and why the activity is performed. erational voice communication also includes facsimile for switching sequence orders. The main divider between the different types of Mainte- Also, the means of using electronic mail (e-mail) for trans- nance is related to whether the maintenance activity is per- fer of switching sequence orders is considered. formed before – in Preventive Maintenance (PM)– or after – Corrective Maintenance (CM) – a fault occurs. These two B. Administrative Operational communication requirements main types are then further divided into sub categories. De- In addition to real-time operational communication, infor- pending on the terminology used, and the industry in which mation is needed that, in more detail and afterwards, support the terms are applied, this division of maintenance can be description of what has happened in minor and major power further elaborated on. system disturbances. This class is referred to as administrative The simplistic view on the maintenance approaches is to operational communication. This is the class of communica- prefer PM to CM, by this minimizing the number of faults. tion that is of interest in this study. Maintenance data, However, preventive maintenance solely is not only utopian, although critical to reliable operation of the power network is in that all faults cannot be prevented; it is also not desirable not time critical. Examples of communication needs in this due to the high costs involved. The real case is more class are interactions with local event recorders, disturbance complicated. For example, corrective maintenance may be recorders, and power swing recorders, all usable as input to more cost effective when the severity of the consequences of a e.g. maintenance planning. fault is low. The choice of maintenance approach is 3 determined by the continuous process of Maintenance graphic Information System (GIS). Documentation in a GIS Management at the utility. based platform has the obvious advantage of providing ease of access to the location of equipment, cables and overhead lines IV. IT SUPPORT FOR MAINTENANCE when access to the equipment is needed. It is also a matter of Clearly, the maintenance process can benefit from support personal safety that high-voltage underground cables can be from information systems. Computerized Maintenance Man- pinpointed with high accuracy. However generally speaking, agement Systems (CMMS) have a long tradition in many in- there is room for improvement for Asset Documentation in dustries. For example, such CMMS contain functionality for two areas: data quality and data depth. inventory and resource management, plant documentation and a) Data Quality fault statistics; see  for an overview of functionality. Obvi- The data quality issue is the historical concern of whether ously these Information Systems are dependent on communi- the data in the systems really represents a true image of the cations networks to interact with the systems controlling the grid. For the low-voltage section of a power grid, there is sel- power grid and also to some extent the grid itself in terms of dom any remote control, and thereby no automatic detection the protection equipment. of equipment status. Surprisingly often is the low-voltage The tradition of IT support for Maintenance is not as estab- section of a utility documented by means of pen, paper, and lished within the power industry as in other industries, e.g., needles on a map, with obvious consequences for data quality. manufacturing or process industry. The survey  showed The data quality issue is further complicated by the low IT that, in the pulp & paper mills had achieved a much tighter usage in the field by maintenance and repair crews. integration of their Asset Management IT systems, one had b) Data depth implemented a comprehensive CMMS and the other was in By data depth we mean the level of information of the asset the process of implementing it. On the other hand none of the in the database beyond merely its location. The historical use surveyed utilities utilized a comprehensive CMMS in support of GIS systems for asset documentation have led to a situation of maintenance operation and planning. Instead, at the utilities where documentation is lacking in detail with regards to both a large collection of systems was used, ranging from office static data such as manufacturer, age, and product specifica- packages, e.g., Microsoft Excel and Access, to components tions, as well as to dynamic data, such as latest overhaul, from large scale business platforms, such as SAP R/3. common faults, and connected customers. Common for all utilities was that at the center of the Asset 2) Implications of a Broadband WAN Management tools was a Geographic Information System For Asset Documentation both challenges of data depth (GIS) to which components have been added as new needs and quality can be addressed with improved communications. have arisen. The integration between the GIS system and the A broadband WAN extended to equipment in the field adds other components range from e-mail and “cut & paste,” as the possibility of automatically uploading configuration data indicated above, to moderate levels of integration, such as (of course dependent on capabilities of the local control sharing databases. systems) thereby mitigating the data quality issue. Additionally, ample communications at substations enable A. Areas of Improvement field personnel to communicate with central systems more The survey indicated a relatively diverse focus when it effectively, thereby enabling the update of asset information comes to the utilities’ plans for improvement of the IT when actually on site, instead of having to do so once back at support. However, the efforts can be categorized in the the office. following areas of opportunity: C. Resource Management • Asset Documentation The concept of Resource Management refers to the IT sup- • Resource Management port for budgeting and follow-up of use of resources, in terms • Production Management of expenditure and internal resources, such as vehicles, tools, • Workflow Management spare parts, and personnel. This is of course a corporate wide • Maintenance Planning task, but it is here focused only on the aspect of Asset Man- In the following sections the potential for improvement of agement. maintenance IT support is discussed with a focus on the impli- A general concern regarding Resource Management at the cations and possibilities created by a Broadband WAN. utilities is the differentiation between daily operation and pro- B. Asset Documentation jects initiated by an investment in, for example, network ex- The concept of Asset Documentation refers to understand pansion or major overhaul of a substation. A common ap- IT support for documenting all aspects of the grid, plant, or proach among the utilities is to assign standing project codes facility being managed. This includes documentation of the for daily activities such as inspections or minor repairs, and geographic location of the equipment, its age, type, status, log all costs to these codes. More ambitious methods involve latest events, etc. work-orders with cost center codes even for minor repairs. For At the utilities, Asset Documentation is very much centered the surveyed utilities, no method was found to be in majority. on documentation of the electric power network in a Geo- Consistently smaller utilities used less ambitious methods. A trend among the larger of the surveyed utilities was to 4 outsource functions such as inventory and field repairs to con- quences of outages. tractors. A rationale stated by all utilities that had outsourced Documenting interruptions from a technical perspective has all or parts of these functions, was to achieve better control of a long tradition. However, the survey shows that technical or resource usage and control of expenditures. Although, none operational experiences are very seldom fed-back into the or- could show any clear evidence of having achieved reductions, ganization in a structured manner. Of course, individuals draw since the concept was still new, most of the utilities reported a their own conclusion and learn from mistakes in the past. better visibility of costs. Outsourcing of inventory and field However, on an organizational level, none of the utilities had crews opens up the question of IT-support and ownership of implemented IT support for collecting experiences from fail- data and IT-systems for these functions. Regarding Inventory ures. Such support can most easily be implemented by proper management, the three utilities that had outsourced their in- asset documentation and workflow support thereby enabling ventory were also relying on the contractors’ IT support for storage of data about events and actions taken and relating managing the inventory and purchasing functions. For out- them to objects in the network. sourcing of field crews, the opposite solution had been 1) Implications of a Broadband WAN chosen, where the one utility, which had completely Documentation of the operational experience of interrup- outsourced their field repairs, managed the IT support itself tions is clearly supported by improved WAN communication. and let the contractor’s personnel report and work in that Although, perhaps not used as part of resolving a fault, data system. stored in local control systems at the substation level can be 1) Implications of a Broadband WAN uploaded to provide after action analysis of faults. These, Efficient resource management is dependent on detailed in- often large amounts of data are available only if the formation on the utilization of resources, including staff, communications network has the necessary capacity. By equipment, and materials. Via a broadband, WAN resources means of a broadband WAN, an analysis is enabled of large in the field can communicate with a central system more amounts of data from several distributed sources Also, the effectively reporting status, and current activities, thereby operational experiences can be much better documented. providing the necessary detail for managing the resources E. Workflow management efficiently. Additionally, third parties, such as maintenance contractors, can be given access to local control systems via The concept of Workflow Management refers to the IT the WAN, thus enabling them to interact directly with local support for managing the propagation of work tasks through control systems. the organization. Typical examples are the chain of events that need to happen after a fault has been detected during an in- D. Production Management spection and some kind of repair needs to be done. The concept of Production Management refers to the IT The survey showed that workflows within the maintenance support used for tracking the quality of the delivered power, and operations teams are very often managed manually, with such as event reporting and outage management. This ties in little or no IT tools used to guide the operation. This is true closely with the role of SCADA systems used in operation of both for planned activities as well as for event-based activities the power network. such as responding to a reported power outage or other cus- Whereas SCADA systems are used to detect errors in the tomer-experienced problem. Although all utilities had imple- network and perform re-configurations to restore a failing grid mented a project-planning tool, none used any workflow-sup- to a stable state, IT systems for Production Management are porting tool. Many respondents voiced the sentiment that too used to record data about the incidents and provide support for much support for the workflow would hamper the creative actions to take to rectify the problem. A further function is the nature of the individuals in the field. generation of statistical data for quality analysis and network 1) Implications of a Broadband WAN optimization. Production interrupting events can be evaluated The area of Workflow Management is perhaps that which re- from several perspectives. Two obvious perspectives are eco- ceives the least direct support from a broadband WAN solu- nomic consequences in terms of lost revenues and operational tion. Clearly, improved remote communications enables use of experiences to be drawn from the incident. more sophisticated IT support in the field. For workflow man- The economic consequences of an interruption are not only agement, this indirectly means that field crews can communi- internal to the utility, in terms of lost revenue for power not cate more effectively with a centralized Workflow system, delivered and direct costs to restore the failing equipment, but both to receive new work tasks, and report the progress of as- also costs incurred by customers for lost production due to the signed tasks. power outage. Despite these potentially large costs, the eco- F. Maintenance planning tools nomic consequences of an interruption have largely been ne- The strategic planning process at the utilities regarding As- glected. Instead, the focus is to resolve the problem and return set Management is very long-term, due to the nature of the to normal operation as smoothly as possible. All utilities in power grid equipment. Typically, the equipment has a depre- Sweden are now under mandate to report all planned and un- ciation period of 40 years or more. As a result, the utilities planned outages to the authorities. Furthermore, a new regu- have had an opportunity to develop elaborate guidelines for latory reform is currently being implemented that may change maintenance and engineering of electric networks. However, the previous lack of concern regarding the economic conse- 5 many of these guidelines have been developed during the long factor, not the available technique itself. Also, to investigate period of monopoly, when customer tariffs where cost driven, the maintenance requirements imposed on the needed commu- and the expense of periodic maintenance could easily be for- nication capacity is another important work to carry out. warded to the customer. Another consequence of the longevity of the network is that equipment, once top of the line, is aging VI. REFERENCES and sometimes stands side by side with high tech equipment,  G. Ericsson: “On Communication in Power System Control,” Ph.D. creating a very heterogeneous environment with very different Dissertation, ISRN KTH/ICS/R--96/2—SE, Royal Institute of Technol- ogy, Stockholm, SWEDEN, 1996. requirements on maintenance.  G. Ericsson: “Classification of Power Systems Communications needs IT tools for planning of maintenance activities, and also and requirements: Experiences from Case Studies at Swedish National support for “replace versus repair” decisions are not in any Grid,” IEEE Transactions on Power Delivery, vol. 17, no. 2, April 2002, common use, and this is an apparent area for improvement. pp. 345-347.  L. Pintleton, N. Du Preez, F. Van Puyvelde, " Information technology: Today most planning activities are done using pen and paper opportunities for maintenance management," Journal of Quality in and sometimes documented in spreadsheets. For periodic Maintenance Engineering Vol 5, No. 1, pp 9-24, 1999. maintenance this may be sufficient, but cleverer use of re-  Bertling L., Eriksson, R., Allan R.N. ”Impact of maintenance on cost and reliability of distribution systems”, In Proc of 17th International sources require a more elaborate way to plan maintenance ac- Conference on Electricity Distribution Barcelona, 12-15 May 2003 tivities. Ideally, systems for maintenance planning would be  P.Verho, K. Nousiainen, "Advanced use of information systems provides integrated with resource and workflow management, as well new possibilities for asset management of high voltage devices," In Proc. NORD-IS 03 Nordic Insulation Symposium, Tampere, Finland as with asset documentation systems.  G. Ericsson: “Communications Requirements – Basis for Investment in a 1) Implications of a Broadband WAN Utility Wide-Area Network,” IEEE Transactions on Power Delivery, Maintenance planning is dependent on both operational as vol. 19, no. 1, January 2004, pp. 92–95. and historical data. Operational data is collected via two chan-  J. Endrenyi et.al. "The present status of Maintenance Strategies and the impact of Maintenance on Reliability”," IEEE Trans. Power Systems, nels: via routine inspections by field crews, and via event log- vol. 16, No 4, pp. 638-646, Nov 2001. ging by the operations staff. A broadband communication fa-  M. Gammelgård and L. Nordström, "Effects of new regulatory frame- cility will enable more data to be gathered from the power works on utilities investment in Asset Management," in Proc. 2004 In- ternational Conference of Maintenance Societies. system. Locally stored error logs at substations or generation  N. Jonsson and L. Nordström “Strategies for implementing IT support facilities can be uploaded to central planning systems provid- for Asset Management” in Proc Powercon 2004, Singapore. ing much more information than the limited data collected by  European Standard EN 13306, Maintenance Terminology, European Committee for Standardisation, Ref No EN 13306:2001E the SCADA system. With a more detailed view of the status  C-G Lundqvist, J. Jacobsson, “Enhancing Customer Services by effi- of equipment, the maintenance efforts can be more precisely cient integration of modern IT-systems for Asset Management and Net- planned and executed. work Operation, In Proc of PowerCon 2002, Kunming, China, October 14-16, 2002. V. CONCLUDING REMARKS AND FURTHER WORK By introducing a broadband utility wide area network, im- provements will mainly be found in “class B,” i.e., in class of communications for administrative operational purposes. Here, the broadband possibilities will act as an enabler for transmitting large bulks of data from end to end. It is also in this class of communication that the bulk of maintenance data belongs. Based on a survey of Maintenance IT system improvements the paper highlights specific benefits of improved communication, divided into: • Asset Documentation • Resource Management • Production Management • Workflow Management • Maintenance Planning For each of these areas, the implications of using a broad- band WAN is elucidated. In general, the high-speed communi- cations make it possible to transfer large amounts of data, pro- viding the actual means of more structured handling of data loads. For example, byte-size demanding maps, drawings, manuals, etc., can now be transferred in digital form to/from the central office and a substation. A suggestion for further work is to more deeply analyze how to use the available bandwidth for a utility. Here, the imagination of the human being is most likely the limiting 6 VII. BIOGRAPHIES Lars Nordström (S’2004) graduated from the Royal Institute of Technology in Stockholm in 1998, and holds a M.Sc. EE and Licentiate of Technology in Industrial Control Systems. Currently Mr. Nordstrom is active in the EFFSYS research program working on use of Information Technology for Maintenance Management in the Power and Pulp & Paper Industries. Mr Nordstrom is also Program Manager for the “IT in the Power System” research program at the Swedish center of Excellence in Power Engineering. Göran N Ericsson (S’90 – M’96) was born in Huddinge, Sweden, in 1963. He received the Ph.D. degree from the Royal Institute of Tech- nology (KTH), Stockholm, Sweden, in 1996. In 1997, he joined Svenska Kraftnät (Swedish National Grid), Vällingby, Sweden, to work on data- and telecommunication-strategic issues. From 1998 to 2000, he was the Manager of the Telecommunications Department. Since 2001, he is a telecommunications planning and project manager.
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