Introduction

The three topics below show how Brazil is pragmatically handling Wide Area Protection Systems (WAPS) nowadays. Brazilian main WAPS aim to prevent mostly the occurrence of electromechanical unstable conditions.

In fact, Brazil has a long experience with the so-called Special Protection Schemes (SPS), both for NIPS alternate current part, as well as for its 7,000 MW ± 600 kV HVDC link. Even before the creation of WAPS concept in the international scenario, Brazilian engineers noticed that SPS application in a 7,000 MW 765 kV AC interconnection needed something designed and tested with extra care. So far, the need for a SPS was identified during operating planning studies and simulations, leading to a rush in the SPS engineering. Bearing in mind that power plants and substations had analog secondary systems, one can imagine what kind of race against time was put on and how pragmatic some solutions had to be. All those initial problems were overcome by digital technology and earlier identification of the need of a WAPS

Up to now NIPS has 306 WAPS and SPS (Special Protection Schemes) in service. Table 1 summarizes how many systems and schemes are in service for each macro-function.

Right now Brazil has a country -wide on-going project for a Wide Area Measurement System (WAMS) for NIPS. Brazilian WAMS is based on synchrophasor measurement technology and aims to provide better input data for the State Estimators running at the Regional Control Centers and a post-mortem disturbance analysis system. The disturbance analysis system will lead the experts to improve models, SPS and WAPS. The application for improving State Estimator performance, by providing the phase angles and trying to make the algorithm as linear as possible, is taking place under the ISO coordination. The idea behind Brazilian WAMS is to give freedom to the utilities to buy their PMUs from a wide range of manufacturers, so tests were performed at the National Institute of Standard Technology (NIST) in Washington DC (US) to check how the PMUs of many vendors cope with the technical requirements. The great challenge of this WAMS is the Super Data Concentrator which is necessary to be on top of the pyramid of data concentrators belonging to G & T utilities.

A stimulating fact for getting along with Brazilian WAMS is the evolution of the Supervision and Control Systems now in service in the Regional and National ISO Centers towards a unique and revolutionary SCADA/EMS based on the Evergreen concept and designed to be in service and permanently updated until 2020 or more. The features conceived for the new SCADA/EMS are so interesting that they deserve an exclusive paper to describe them. But the fact is that there will be one single (fully backed-up) State Estimator running for the whole NIPS.  This requires top quality input data, so accurate snapshots shall be taken for improving the output of Real-Time Applications, such as power system security assessment. Such an assessment – similar to a “radar system” – is already running in the ISO Regional Centers with fair steady state performance, but its dynamic improvement depends on the State Estimator, which claims for data from a WAMS. The “radar system” works by showing the operating point and how close or far it is from the limits (a polygon) pre-determined by operating planning studies. In reality, due to accuracy issues, the operating point should be a spot and the polygon sides (straight lines) should be areas, but their sizes are yet unknown. The WAMS’ two initial products plus some deep metrological studies will pave the way for the accurate representation of the operating point and the limit straight lines.            

For the moment, at least as far as the authors are aware, there is no specific Wide Area Control System (WACS) in Brazil. The expectations are that the experience with the WAMS will be a turning point to start working with WACS.

For the near future, all systems mentioned above shall be joined in a Wide Area Monitoring, Protection and Control System (WAMPACS), as long as experience and confidence is being gained with WAMS, WAPS and WACS. NIPS is quite prone to wide area applications, because it has five hydro-generation areas with different hydrological regimes. The most tempting advantages of WAMPACS envisioned by Brazilian engineers are adaptive, protective and control systems. In that way, all changes eventually needed by protection and control systems will be executed automatically according to particular operating conditions.