روش جدید برای محاسبه زمان واقعی از شاخص های کیفیت توان بر اساس فازورها فضای آنی

One of the important issues about using renewable energy is the integration of dispersed generation in the distribution networks. Previous experience has shown that the integration of dispersed generation can improve voltage profile in the network, decrease loss, etc. but can create safety and technical problems as well. This work report the application of the instantaneous space phasors and the instantaneous complex power in observing performances of the distribution networks with dispersed generators in steady state. New IEEE apparent power definition, the so-called Buchholz–Goodhue effective apparent power, as well as new proposed power quality (oscillation) index in the three-phase distribution systems with unbalanced loads and dispersed generators, are applied. Results obtained from several case studies using IEEE 34 nodes test network are presented and discussed.

One of the important issues about using renewable energy is the integration of dispersed generation (DG) in the distribution networks (DNs). Various investigations showed that DGs integrated into utilities’ DNs could affect the host DNs in number of ways. Previous experience has shown that the integration of DGs into DNs could create safety and technical problems. They may contribute to fault currents, cause voltage flickers, interfere with the process of voltage control, increase losses, etc. Actually, overall model of the distribution system should be renewed, since the impact of DGs on the DNs planning and operation is significant. Therefore, the main question here is: “What is the impact of the DGs on the overall system performance of the distribution system?” In this paper an investigation of the integration aspects of DGs in the three-phase DNs with unbalanced loads is presented. This work reports the application of instantaneous space phasors and the instantaneous complex power in observing performances of the DNs with DGs in steady state. New IEEE apparent power definition, the so-called Buchholz–Goodhue apparent power, as well as new proposed power quality indice in the three-phase distribution systems with unbalanced loads and DGs, are applied. It is shown that new proposed indices together with the existing indices are efficient tool for observing performance of the distribution systems with DGs. Results obtained from several case studies using IEEE 34 nodes test network are presented and discussed. This paper consists of seven parts. In the second part handling PV and PQ nodes in the power flow analysis of distribution systems with DGs is shortly explained. In the third part the basis of the instantaneous complex power theory is presented. The fourth part contains the Buchholz-Goodhue effective apparent power definition, new power quality (oscillation) index and the three-phase power factor definition for unbalanced sinusoidal condition. In the fifth part application of the instantaneous complex power theory on the IEEE test feeder with DGs is presented. The conclusion is in the sixth part and the final part contains the list of references.

This work reports the application of the instantaneous space phasors and the instantaneous complex power in observing performances of distribution networks with dispersed generators in steady state. New IEEE apparent power definition, the so-called Buchholz–Goodhue apparent power Se, as well as new proposed Power Oscillation Index, the POI, are applied on a three-phase distribution system with unbalanced loads and DGs. The simulation results show that the integration of the DG into the considered DN improved the system voltage profile and decreased the effective apparent power and, consequently, the line losses. However the power factor PFe and the Power Oscillation Index POI deteriorated. This is very interesting, but expected system behavior as well, since the DGs do not deliver negative and zero sequence power in the system. It should be noticed that the vector power factor, PFV, remained unchanged for different levels of power generation, showing its insensitiveness on the evaluation of such systems. There is a relation between the effective power factor PFe and the unbalance reflected on the Power Oscillation Index POI: while the effective power factor PFe decreases, the Power Oscillation Index POI increases (Table 5). The POI gives us the additional information that losses increase also due to the active power oscillation increasing, not only due to increasing reactive power circulating on the system. The PFe reflects both phenomena but does not separate that information. The usage o the IEEE-Buchholz-Goodhue effective apparent power Se shows its importance on the evaluation of the distribution system utilization capacity which normally operate with high power factor per phase but with great level of unbalance. The instantaneous space phasors (ISP) method applied in this research is an alternative for the calculation of the Buchholz–Goodhue effective variables. In addition, the ISP method allows the evaluation of the real power oscillation due to voltage and current unbalance. Besides, the ISP method gives a deeper interpretation of the interaction of positive and negative sequences components. It is suggested that the real power oscillation be taken as one more element in analysis of real-life distribution systems.