Concerns and dreams about the future

Having an interconnected power system 4,000 km long (North-South), Brazil optimizes its interconnections power flows, thanks to different hydrologic regimes among its hydro generation areas. So, active and reactive power flows experience wide changes during the year. It is not uncommon that sudden changes be imposed by contingencies or by mutual assistance with Uruguay and Argentina. One example of this operation criterion is having heavy loaded interconnection lines during light load conditions. Another one is the recent installation of usually light loaded interconnections across transmission trunks between hydro generation areas and load regions, so the trunks may help one another in case of internal contingencies through light loaded paths. Soon, Brazilian System will be 4,000 km large as well.

All mentioned above may be enhanced and optimized again in wider and more accurate basis, if new tools are effectively introduced and applied up to the limits of their capabilities. Among them, IEC 61850 plays an utmost important role, but secondary systems based on the new standard will have to be applied considering local and system wide viewpoints.

Despite having specialists ready to handle IEC 61850 systems, Brazil needs them to be in permanent evolution. This means the involvement of all hierarchical levels. Only by convincing utilities' managers, directors and CEOs, it will be possible to spread knowledge absorption and to go beyond training.

Of course Brazilian SC B5 is a natural forum for training, but stronger stimulation is needed to involve the managerial level with this subject. It could be done by (ANEEL) or Brazilian ISO (ONS). The authors believe that once ANEEL, ONS and utilities' boards are "polarized", Brazilian SC B5 will be able to handle all details.

IEC 61850 is being enhanced to be suitable for power plants and inter-substation applications. Process bus is already a reality. IEC 61850 will probably be the most adequate vehicle to introduce interoperability and other facilities at control center level. These statements show that a distributed processing net (DPN) from the bay up to the control center levels will be feasible in a few years (Figure 5). To reach such a goal, secondary systems shall be considered a cooperative service, so the way for national planning will be paved. Then the usual questions (what, why, who and how?) will be raised - and solved. If national planning is not achievable, than the utilities and Brazilian ISO will behave as the opposite of "The Three Musketeers": each one for itself! Through this winding path the same goal may be reached, but spending much more energy.

DPN optimized use from the bay up to the control center levels raises many issues, as stated in the paragraphs below.

Nowadays the basis for adaptive protection is well established for intra-substation applications. On the other hand, the adaptive protection concept and application to cope with system-wide prevalent conditions (SWPC) is yet to come. Many line and transformer protection settings could be automatically optimized for SWPC forecasted by operative planning studies. For functions as out of step blocking and tripping (68OSB and 68OST) and loss of synchronism (78), the inclusion of system-wide adaptive features will be most welcome. The proper control center level (utility, regional or national) shall be defined. How to calculate and mostly how to decide the moment for a setting change are the main challenges for national and international R&D activities. The same certainly will benefit adaptive control systems. Adaptive features will be implemented easily at substation or power plant level by IEC 61850 based systems.

Brazilian Grid Procedures demand that the secondary systems of new installations shall be capable of supporting generic Special Protection Systems (SPS). Efficient SPS require both local and upper level facilities for their broad application. There are expectations that the SPS added cost imposed to secondary system costs shall be reduced by overall optimization provided by IEC 61850 inherent benefits. Among these benefits, interoperability is the one that leads to reduced engineering costs for similar SPS!

Metrological studies are needed for defining one single measuring system for all supervision, control and measuring (including revenue measurement) functions. In a DPN environment, measuring systems (MS) shall move from many independent systems to a single one - at least to a single basis. The profusion of MS based on independent IEDs and the legacy of old MS, sometimes imposes misleading interpretation when distinct readings of the same electrical quantity are compared. Reaching measurement uniqueness requires metrological studies not yet performed in Brazil or elsewhere and depends on large international debates that may be carried out by CIGRÉ SC B5 and pushed by PAC World. How can one have a secondary system with all facilities provided by IEC 61850 and insist on having different methods to measure frequency, voltage and current and then calculate active and reactive powers and energies by distinct algorithms? How to proceed in substations and power plants where phasor measurement is required for system wide applications? The challenge is stated!

In a DPN environment, SCADA systems shall evolve to handle information with high added value and not process data anymore. The transformation of data into information shall start at IED level, maybe at merging unit level. The evergreen concept is the way for SCADA systems to keep pace with the evolution reached at substation level through IEC 61850. Energy management systems (EMS) will be spared for more sophisticated goals. The combined use of IEC 61850 and phasor measurements will certainly lead to system topology/ state monitoring and dynamic state estimation. Static state estimators and topology estimators will not be necessary anymore. As Dr. Apostolov stated during his courses in Brazil: "power systems are on their way to use dynamic state estimators and all the benefits they will bring in ensuring the stability of large electric power systems."