Reactive Power Assessment including Renewable Energy Sources

Abstract

The interest in renewable energy sources has increased significantly due to environmental issues and fossil fuel's elevated cost. Fossil fuel consumption increases the emissions of carbon dioxide and global warming. The perspective of global warming suppression and sustainable energy development, recently renewable energy such as wind generation and photovoltaic generation (PV) are getting attention world wide. Therefore,usage of renewable energy in the form of distributed generators (DGs) has increased rapidly. However, DG using renewable energy is influenced by the weather. Therefore, maintaining the voltage in the distribution to a statutory range becomes difficult. In addition, conventional distribution systems have been constructed without consideration of DG connections. Consequently, certain problems e.g. reactive power support, active power transmission, line loadings etc. emerge as a new problem as opposed to conventional case. If large amount of DGs using renewable energy are installed to a distribution network, voltage deviations and fluctuations based on output power fluctuation of DGs will become a significant problem. So the reactive power in the grid is needed to keep the external(grid) voltage at the desired value. The correction of deviation of the external voltage from the nominal require the supply of the reactive power to the grid. The needed amount depends on the current value of the active power supply. It should be recognized that system voltage level affects a generating plants ability to deliver reactive power to the grid and the power systems requirement for reactive support. The task is to assess reactive power in a considered system due to DG penetration and provide suggestions to maintain voltage support mechanism.