Abstract. Power quality problems related to short or long time voltage variation have motived the search for voltage compensator techniques capable to provide dynamic voltage regulation to accomplish voltage supply levels in accordance with electrical energy agencies acceptable levels. Although one could recognize that a variety of products already offered in the market are capable of attending general electrical power system requirements the available technology comprises quite simple devices till very sophisticate ones. Having in mind the combination of simplicity, competitive cost, low maintenance need and an attractive performance at recovering the voltage deviations, then an electromagnetic concept to restore the desirable voltage within the established voltage levels is here proposed. The control strategy to be used can provide properties that enable this new device at proving the time response in accordance with the needs for long term and short term voltage variations. Concerning the proposed compensator physical topology it consists in extracting the necessary electrical power throughout a shunt transformer and the injection via a series unit. Besides the arrangement, the paper goes further by establishing a computational time domain model and a laboratory experiment to highlight the overall structure effectiveness at compensating voltage changes.

In face of its oil reserves characteristics, deep and ultra-deep exploitation have become a vital issue for Brazil 1, In those cases where the oil field does not have enough pressure to ensure natural oil flow from the bottom of the sea to the platform, the process will require the use of variable speed inverter-fed sub sea electrical motors placed fat away from the electrical energy source. This implies in a new operational condition for the electric system, which is the electrical energy transmission with variable frequency, through long length cable, in the sub sea environment. The behavior of such systems has not yet been extensively studied, and in face of the coats involved, careful analysis is mandatory. The paper presents a power simulation tool developed to the analysis of such electrical systems. The analysis is carried out in time domain. Harmonics components of voltages and currents and their effects on the system operation are analyzed. Comparison of simulated and measured results for an actual working installation is shown Simulation results for a long length cable transmission system are discussed. Introduction Offshore oil exploitation in shallow waters is a well established technology world-wide, However, when it comes to the oil extraction in waters deep more than 400m, experience starts to become restrict, and for depths over 1000m. mature technology is stall under development. Brazil has particular interest in developing deep water exploitation schemes, as 64°/0 of all its assured oil reserves, and 65% of all the potential discoveries are found to be in deep and ultra-deep waters, i. e., depths over 10OOml. PETROBRAS is already successfully exploring a well completion at 1027 m V/D (water depth), but in face of the challenge imposed by the characteristics of its reserves it understands new technologies must be developed. This has called for a comprehensive and well coordinated development program which involves all aspects concerned with ultra-deep water exploitation and has been set up by PETROBRAS through the PROCM-200($. Among the several objectives of this program stands the research and development of technologically innovative projects aiming to provide technical capability in electrical systems to exploit deep and ultra-deep oil marginal fields using sub sea hosting systems, reduce investment and operational exploitation costs, and the extension of the useful life of wells located at deep and ultra deep waters. In this context, directions for reducing or even eliminating the number of platforms by using sub sea boosting systems has gained particular attention. These sub sea boosting systems comprehend the use of electrical submersible pumps placed directly in the wells, sub sea separation and multiphase flow pumping arrangements placed at distances of 25 km or more from the Production Unit. Under the operational point of view this indicates that electrical Energy is to be transported along these distances via sub sea cables. Furthermore, for the efficient operation of the production systems, adjustable speed motors located at the bottom of the sea are necessary, thus electrical energy transmission through long sub sea cables with variable frequency is required.

Absfract-The tnherent differences in the accuracy of measunnglmonitoring power quality (PQ) instrumentation has led the Brazilian Transmission Independent System Operator (ONS -Brazilian ISO) ONS to conduct a comprehensive field campaign and laboratory tests. These tests have allowed for evaluation of the accuracy and measurement methodology for a large number of commercially available instruments. This paper presents the laboratory test results for the performance of the different instrumensts. AN of the instruments were simultaneously fed the same voltage signal. Lab tests were conducted which included most commom power quality indices such as: steady state voltage, frequency variation, unbalance voltage, voltage fluctuation and short duration voltage variation (sag).

The present paper focuses an electromagnetic device to restore busbar voltages to acceptable limits using an electromagnetic arrangement conception. The new device has been called by electromagnetic dynamic voltage restorer (EDVR) due to its physical structure. As for the insertion of the degree of the series voltage compensation, two approaches are considered. The first can be recognized as a discrete procedure as the restoring voltage procedure makes use of electronically switched tap changers. The second relies on a continuous voltage variation offered by a single tap supply and a controllable electronic device. It is shown that the overall compensator idea lies on positive or negative insertion of a variable voltage in series with de feeder so as to achieve a consumer supply voltage in accordance with acceptable levels. The device comprises a traditional shunt autotransformer linked to a series transformer which provides the necessary restoring property. The paper highlights the EDVR physical structure, the control units, the ATP platform models and results associated to case studies to show the overall compensation equipment and control performance offered by the given solutions.

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