The study reviews and examines the definitions of reactive power, apparent power, and power factor. Among the different definitions of power factor in three-phase circuits under a non-sinusoidal condition, this study adopts the definition of the effective power factor, which is also advocated by IEEE Standard 1459-2010. The effective power factor is defined as the ratio of the real power consumed by the load over the effective apparent power. The effective apparent power is the maximum power transmitted to the load (or delivered by a source) while keeping the same line losses and the same load (or source) voltage and current. The effective power factor theory gives apparent power a definite physical significance and provides more insights than other definitions in unbalanced circuits. Another merit of the effective power factor definition is that it only involves measurements and computations in the time domain. This study implements the computation of the effective power factor in MATLAB for use in PSCAD/EMTDC. The latter simulates the power system and provides three-phase voltage and current measurements. MATLAB performs the effective power factor computation and sends the results back to PSCAD. A number of simulations are provided in this report to demonstrate the validity and the accuracy of this implementation. / text

Orientador: Antonio Padilha Feltrin / Resumo: As redes elétricas de distribuição em sua maioria apresentam cargas elétricas desequilibradas. Por isso é necessário estudar as potências envolvidas em sistemas trifásicos desequilibrados e a compensação das mesmas. O desequilíbrio aumenta as perdas elétricas e diminui o fator de potência da rede elétrica. Esse trabalho propõe a compensação da potência reativa e do desequilíbrio na rede com a finalidade da diminuição das perdas elétricas e a compensação das componentes de sequência desequilibradas da corrente. A utilização da teoria da potência efetiva em sistemas desequilibrados permite calcular as potências reativas e de desequilíbrio, sendo estas as potências compensadas no método proposto. A teoria da potência efetiva mede a eficiência dos métodos testados. Os objetivos da compensação do desequilíbrio são reduzir as perdas elétricas no neutro e o fator de desequilíbrio da tensão, além da potência de desequilíbrio na rede, potência exclusiva do desequilíbrio e que não realiza trabalho. O método proposto para compensação do desequilíbrio e dos reativos na rede de distribuição a quatro fios consiste na alocação de capacitores em delta ou estrela nas barras trifásicas. O método proposto é comparado com dois métodos existentes na literatura. A comparação entre os métodos permite constatar que o método proposto é mais eficiente na redução do desequilíbrio conjuntamente com a compensação das perdas elétricas. Quanto maior é o desequilíbrio da rede elétrica maior é a vantagem da ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Distribution electrical networks mostly have unbalanced electrical loads. Therefore it is necessary to study the powers involved in unbalanced three-phase systems and their compensation. The unbalance increases the power losses and decreases the power factor of the electrical network. This work proposes the compensation of the reactive power and the unbalance in the network with the purpose of reducing the power losses and the compensation of the unbalanced sequence components of the current. The use of the effective power theory in unbalanced systems allows to calculate the reactive and unbalanced power, these being the powers compensated in the proposed method. Effective power theory measures the efficiency of the methods tested. The objectives of the unbalance compensation are to reduce the power losses in the neutral and the unbalance factor of the voltage, besides the unbalanced power in the network, exclusive power of the unbalance and that do not realize work. The proposed method for unbalance and reactive compensation in the four-wire distribution network consists of the allocation of delta or wye-connected capacitors to the three-phase bus. The proposed method is compared with two methods in the literature. The comparison between the methods allows to verify that the proposed method is more efficient in reducing the unbalance together with the compensation of the power losses. The greater the unbalance in power network, the greater the advantage of the compensation b... (Complete abstract click electronic access below) / Doutor