No abstract

Segmentation of large AC systems through DC links introduces a new concept that utilizes the advantages of direct current transmission to improve network reliability and increase power transfer capacity. Technical literature argues that the segmentation of the AC network and the introduction of DC links at these systems connection points bring benefits to system operation, once contingencies generated on one side of the DC connection point would not be reflected on the other side of DC connection, thereby reducing the likelihood of cascading shutdowns and blackouts due to load restraint on transmission lines and transformers. Amidst this scenario, this paper presents a study of the main topics regarding the use of this new network segmentation philosophy, bringing a practical point of view for the use of this concept at the electrical power system planning. The effect of DC segmentation before a contingency that would initiate major outages in an adapted electrical system model IEEE-14 bus is studied and simulations have been performed with test HVAC systems and segmented by HVDC link. The results have been compared, principally in relation to the voltage bus, reactive power generation, system losses and power flow at the lines, and demonstrated that this new concept improved the grid reliability.

Abstract. The growing demand for electric power together with the environmental agencies pressure for decreasing polluting gases emission are the main causes of the big expansion that Distributed Generation systems have been undergoing lately. This kind of electric generation system allows to produce parts of the electricity power nearby the costumers making energy costs cheaper for final consumer and improving the share of clean sources on the energy matrix. Despite Germany's great experience with photovoltaic plants, Distributed Generation systems are not well widespread around the world. Most governmental regulations about the theme are recent and sometimes do not cover all the specificities, so it has been continuously rewritten. Although Brazilian market has a small concentration of sources connected to the distribution grids, the annual relative growth is significant. High concentration of sources nearby the costumers may cause problems in the operation and in the stability of electric quantities. Some of these problems are voltage rises, harmonics and general damages to electrical equipment. This paper presents the voltage rise effect in distribution grids with high concentration of generators; it also suggests mitigation techniques for this outcome. It becomes clear that is possible to reverse power flow without voltage rise beyond legal limits.

The growing demand for electric power together with the environmental agencies pressure for decreasing polluting gases emission are the main causes of the big expansion that Distributed Generation systems have been undergoing lately. This kind of electric generation system allows to produce parts of the electricity power nearby the costumers making energy costs cheaper for final consumer and improving the share of clean sources on the energy matrix. Despite Germany's great experience with photovoltaic plants, Distributed Generation systems are not well widespread around the world. Most governmental regulations about the theme are recent and sometimes do not cover all the specificities, so it has been continuously rewritten. Although Brazilian market has a small concentration of sources connected to the distribution grids, the annual relative growth is significant. High concentration of sources nearby the costumers may cause problems in the operation and in the stability of electric quantities. Some of these problems are voltage rises, harmonics and general damages to electrical equipment. This paper presents the voltage rise effect in distribution grids with high concentration of generators; it also suggests mitigation techniques for this outcome. It becomes clear that is possible to reverse power flow without voltage rise beyond legal limits.

With the objective to reduce the environmental pollution, alternative initiatives have favored the evolution of the electric vehicle (EV). As the electric vehicle depends solely on battery, the grid electric power is need for charging it. This new electric load can cause concern due to the impact of consume on power system. The behavior of main electric parameters is analyzed during the recharge of EV considering an actual condition of diary charge. In sequence, the data of these electric parameters obtained during EV charging were included on residential consumer energy from Brazil. The results contribute to the understanding of the recharge of EV in different time of the day which can affect the curve of residential consumer energy and consequently will affect in different way on Power System.