Performance Study For Distribution Network With High Penetration Of PV Based On Stochastic Power Flow Analysis

Today's power systems are undergoing major changes. These changes are driven by both economical and environmental issues such as liberalization of energy markets, unbundling of utilities, depletion of conventional energy sources and climate change. Therefore it is obvious that former centralized power system is transformed accordingly. For these reasons new technology called distributed generation (DG) is becoming more and more popular due to their advantages such as small size and high efficiency. But at the same time this new technology (DG) has significant impact on the distribution network such as power flow, voltage profile, power quality and grid protection. Based on this, this paper analyzes the influences of distributed generation on the distribution network.At present, distributed generation based on photovoltaic systems (PVS) is growing faster and faster due to the availability of sun on the surface of the earth. This has led to an increasing penetration level of these generating units in the distribution systems. But the PV input is subjected to the weather condition there by affecting the PV output that can also lead to over and under voltage problems. Taking into consideration all these problems mentioned above, this paper conducts study in order to assess the performance of a distribution network. This paper first establishes probabilistic model of PV showing relationship between PV output power and solar radiation also probabilistic load model is given. Finally stochastic power flow method is used. This method uses combined cumulants method and Gram-charlier series expansion with the advantage of reducing the calculation work of convolution and yielding the numerical characteristics of both load and solar radiation. With this new method we will obtain probability distribution of the states variables as well as their probability density function and then voltage quality will be assessed. Test on IEEE34 distribution system with high PV penetration is carried out. It is concluded that this method is really effective and efficient.