Storms with strong winds often cause transmission tower failures and transmission line outages in the area of Brazil where Eletrobras FURNAS is responsible for the generation and transmission system. In these situations, the utility immediately conducts a detailed investigation of an event and initiates an emergency plan that, among other activities, mobilizes maintenance, engineering and support staff to the site of the failure.

The natural environment is usually harsh, complicating restoration logistics. The complexity of the logistics makes communication among the staff all the more vital. However, better telecommunications infrastructure was needed in the service territory to be able to transport field staff and deploy adequate and efficient support services, including materials, to repair transmission lines and restore service in a reasonable amount of time.

Transmission System Performance

From 1970 to 2010, 84 incidents in the Eletrobras FURNAS service territory were linked to storms and strong winds that caused the destruction of 218 towers. The average restoration time of an incident was about seven days. The incidents occurred in locations that were both difficult to reach and in hostile environments. The utility did not upgrade the design specifications for its towers because of the high cost, but maintenance procedures were continuously improved.

Where and when available, very-high-frequency (VHF) radios and cell phones were the only forms of communication the field staff used at a time when no standard communications network was established. It was concluded the infrastructure available for communication was not consistent with the criticality of electricity service.

Another limitation diagnosed was the difficulty of the VHF system to ensure the privacy of communication, which is a delicate issue when it comes to coordinating the work or inspections involving senior management. Even in situations when a cell phone was available, there was a high cost of connection to long distance service.

The main driver for establishing a satisfactory communications system was a change in the industry's regulation whereby utilities are subject to severe financial penalties imposed for incidents that make the transmission system unavailable. This new regulation led to the creation of several process improvements that reduced the average time for transmission line restoration as a result of improved communication.

Technical Solution

The maintenance engineering department of Eletrobras FURNAS identified the severe constraints of the existing communications resources when tower failures occurred and then developed an integrated voice and data system called the telecommunications mobile unit (TMU).

The solution consists of a container equipped with climate control and a reliable infrastructure able to provide telecommunications to the surrounding area of a work site. The TMU can access the public switched telephone network, the Internet, the corporate telephony system of Eletrobras FURNAS, the utility's intranet, and the applications of the utility's mainframe, in addition to providing telephone communication among local users.

Equipment

The voice and data system is equipped to provide wireless communication capability, including full mobility to users. Once installed at the position of a local emergency, all communication is carried to Eletrobras FURNAS' central office in Rio de Janeiro through a single satellite data link. This simplification was made feasible by the adoption of Voice over IP.

Users including security personnel and supervisory staff may have specific extensions. Important visitors who need to be contacted also can have extensions. The design of the system is scalable and the resources can be expanded, if necessary.

The equipment for voice and data has no special design features and can be found on the open market. The transmission equipment, by being more specific, is rented in conjunction with the satellite link, making the project independent of proprietary technology solutions. The contract currently in place includes an antenna with an automatic positioning feature that simplifies the task of activating the TMU. As a contingency mechanism for this system, there also is an antenna with manual positioning features.

Transportation and Positioning

For logistical purposes, the TMU is based in Minas Gerais, in the southeast region of Brazil, but can be moved to the site of a tower failure incident immediately after the triggering of the emergency plan to provide communication services to the field teams.

The TMU is quite compact and does not present any transportation and positioning difficulties, even on irregular ground. Within certain limits, it is not necessary to level the surface.

The energy infrastructure is extremely reliable, ensuring high availability of voice, data and transmission equipment. The refrigeration is achieved by the use of common air conditioning equipment.

Data Security

Once activated, the TMU provides access to enterprise applications through a wireless network, which could have the potential to cause a failure in data security. This issue is resolved by several measures, including the use of firewalls, authenticated login (IEEE standard 802.1X), encrypted access to both voice and data (IEEE standard 802.11i), and connection through a virtual private network. Thus, access made from the TMU has the same security as the rest of the utility.

Financial Solution

All the satellite operators consulted in Brazil refused to accept an on-demand rental agreement that presupposes payment is only levied for days the system is used. Cited was an insufficient economic return or lack of technical conditions to ensure the band was available as and when requested. These companies required a rental fee based on continuous use of the link, which negated the economic viability of the project. At this point, the budgeted annual estimated costs varied between US$95,000 and $145,000.

Extensive consultation convinced one satellite operator (Vodanet — the Brazilian branch of the U.S.-based STM Group) that the brand name Eletrobras FURNAS was highly valuable and the use of the system would bring a good return to the supplier's image, creating new business opportunities in the Brazilian electricity sector. Finally, economic feasibility was achieved by means of a franchising operation at a pre-fixed rate that varies on a daily basis.

Following this model, Eletrobras FURNAS pays the contractor for 30 days of use per annum regardless of effective use. If the annual use exceeds 30 days, the extra days are paid separately by considering the daily value to compose the total contract price. Thus, Eletrobras FURNAS was able to stipulate the fixed value (30 days per year) with the surplus pre-contracted days, avoiding abusive prices. The negotiated cost is about $21,000 per annum, with an extra-day cost fixed at about $450.

The equipment used for voice services and data does not have special features and is easily found on the market. The transmission equipment is specific and has been rented in conjunction with the satellite link. This strategy creates a project that is independent of proprietary technologies, as only the automated antenna is extra and was purchased for $24,000.

The actual use in the field showed the band originally defined in the project, 256 kbps for download, was too slow for some communication demands. As a result, the supplier agreed to increase this bandwidth to 384 kbps or 512 kbps, depending on the demand detected during use. In practice, if the upload bandwidth is not required, it will remain constant at 256 kbps.

Keeping Everything in Perspective

In addition to the expansion of communications facilities, the project can provide increased reliability of the VHF system, which is fundamental and will be used as the energy infrastructure has been designed to also include such equipment. By including the transmission equipment in the rental of the satellite link, Eletrobras FURNAS avoided the acquisition cost, and the project became totally independent of the telecommunications companies. This gives the utility the opportunity to modify the project depending on the cost and quality required.

As the utility is already contracted for 30 days usage of the system, if not employed, the TMU can serve as a laboratory to investigate the quality of the satellite link, especially on issues relating to ionospheric interference. The use of commercial equipment common to the functions of voice, data, power and cooling ensures ease of the restoration of services in case of failure. The replacement of transmission equipment is covered by warranty.

Depending on the magnitude of the event, the media may be interested in attending the system incident. In such cases, the TMU can serve as a marketing vehicle for the utility by demonstrating the use of technological resources in incident reporting.

In spite of all the telecommunications features embedded in the project that make it interesting, the realization of this project was only made possible as a result of extended and difficult negotiations with several companies, giving the utility the chance to enhance its knowledge of the technical details of the contracted activity. The work undertaken to convince contractors about the indirect benefits of working with Eletrobras FURNAS were convincing, leading to successful negotiations. In the long term, the contractual innovations may eventually prove to be more important than the technical innovations.

Since the implementation of the TMU in 2010, there have been only two emergency situations, so there is insufficient experience to evaluate the reduction in the time taken to restore the system.


Alexandre Pinhel Soares (pinhel@furnas.com.br) qualified in electronic engineering at the Federal University of Rio de Janeiro and joined Eletrobras FURNAS in 1994. Following positions in maintenance engineering and telecommunications, Soares is now working in the utility's electric and electronic equipment department. Soares has authored a book on electrostatics and has written articles on computer science, meteorology, space geophysics, telecommunications and management.

Ricardo Medeiros (rmedeiro@furnas.com.br) graduated with a BSEE degree from the University of Campinas and a master's degree from the University Estadual Paulista. In 1977, he joined General Electric of Brazil SA, working on quality control. Medeiros joined Eletrobras FURNAS in 1981 and is currently manager of the superintendent of maintenance engineering.

José Antonio Paula Motta (jantonio@furnas.com.br) was awarded a BSEE degree by the Catholic University of Rio de Janeiro and joined Eletrobras FURNAS in 1974. Following responsibilities for telecommunication, supervision, control and automation, Motta was appointed manager of the utility's electric and electronic equipment department. Motta now coordinates the development and maintenance solutions for various areas of the utility's activities.

Companies mentioned:

Eletrobras FURNAS www.furnas.com.br

STM Group www.stmi.com

Vodanet www.vodanet-telecom.com