Power quality management issues over the Brazilian transmission system

The Brazilian energy sector´s recently adopted deverticalized model imposes new rules that must be established in such a way as to satisfy the consumer market. In this context, the power quality itself has become one of the most important issues to be attended. During the last two years the Brazilian Transmission ISO (ONS-Operador Nacional do Sistema Eletrico) has established indices and standards in order to accomplish the adequate power quality (PQ) performance in the basic transmission grid. However, the establishment of indices and standards corresponds the first stage of the management process. As a second stage, the power quality performance throughout the transmission grid should be followed, including the aspects related with measurement strategies, measurement devices, data acquisition philosophy, communication protocols, data base requirements, analysis software to support action decisions, and so forth. In order to support the decisions related with the mentioned first stage, the ONS, in cooperation with the players and their representative agencies, the national electric energy agency (ANEEL), universities and research centers, has implementing measurement campaigns in order to know the actual basic grid performance concerning some power quality indices as well as, in some cases, to evaluate the measurement confidence itself. We present some news and conclusions related with recent measurement campaign (flicker, harmonic distortion and voltage sag) developed by ONS. In order to follow the basic grid power quality performance-second stage - the ONS is developing basic strategies concerning a power quality management system (PQMS) to be implemented in the near future. We present the conceptual issues of this system for some power quality performance indices concerning issues like how, when and where to measure.