Effect of Domestic Power Plants to the Low Voltage Transformer Areas from the Nonlinear Distortion Point of View

Abstract

A case study is presented in this work, where a 4 kW photovoltaic domestic power plant, located in Hungary, has been examined. Based on the measured voltage and current signals we examined the frequency domain behaviour of the power plant and the effect to the power quality, mainly the total harmonic distortion, of the low voltage transformer area. Evaluation of the measurement database suggests that this type of synchronous power injection has serious effect on the voltage distortion of the low voltage grid, and this effect highly depends on the ratio of the injected power magnitude related to the nominal power of the inverter part. The available hardware structure enables us not only to eliminate this phenomenon but also to improve the existing quality of the low voltage grid. It needs only a modified control structure that can be implemented in the inverter control device. It causes power loss reduction in the low voltage grid. This reduction helps lowering the power loss in the phase conductor, and more radically in the neutral conductor of the transportation line. In the case of electric power production from fossil sources, it lowers the greenhouse gas emission, to lower the environmental and social- welfare effects of the climate change. 1. Motivation and aim There is an ongoing discussion in the scientific and public society on the exhaustion of fossil fuel reserves and on how the climate change is affecting our planet. Current opinion says that the primarily emitted greenhouse gases (GHG) from natural and artificial sources are responsible for the effects of climate change. These effect the solar radiation, and thus act as key factors affecting the global weather. Nobody denies the constrained nature of fossil energy resources, but they use optimistic estimations of the quantity and availability of these energy resources, that may become available with the help of new scientific and technological developments. There is a huge literature about the prediction of fossil energy resources, and their effect on the CO2 concentration in the atmosphere, and as a result on further climate change impacts over the next 200 y period of time. The effects of fossil fuels depletion (Chiari and Zecca , 2011), economic growth (Nel and Cooper, 2009), the wind and solar energy production (Leggett and Ball, 2012) and the exploitation of methane hydrate deposits (Glasby, 2003) on global warming is predicted. The predicted CO2 concentration increases significantly, that result in rising average temperature values. The situation is getting worse by the global economic growth, and the extended use of newly available fossil energy sources (primarily deepwater oil and gas deposits) (Nel and Cooper, 2009). Without intervention, significant anthropogenic impacts should be expected in the 21st century. We must influence this process by all means in order to avoid the above described anthropogenic effects. We need to reduce the emissions by reducing the use of resources, which produce greenhouse gases. Surveys suggest that the economic sectors responsible for CO2 emission in the European Union are as follows (in descending order): energy and heat production (32 %), road transport (22 %), household