Probabilistic Load Flow Considering The Correlations Among Nodes

There are many uncertain factors in operation and planning of power system. Probabilistic load flow can account for these uncertainties in the system. However, the general probabilistic load flow assumes that the system is independent among nodes and network topology unchanged in order to calculate expediently and to save computation time. For the different of the load nature, climate, season, etc in the actual system, the relationship among nodes is more complex, and there are many possibilities among the nodes which is not necessarily independent each other. The lines system because of theirs own or external cause, inevitably, will be fault. After line fault the power again distributes and there is a certain correlation among other lines in the system. In one word, the actual operation of the system is very complex. In order to accurately reflect the actual system and to provide more realistic and effective reference information to planning and expansion planning of power system. Probabilistic load flow except considers conventional random factors than regard the correlation existing among nodes, the changes of network topology and the correlation among lines.In this paper, there is wind power and solar power generation in system. Then power system establishes the probability model of random variables, considered the system correlation among nodes and the slip road slip roads broken after the power disconnected transfer caused by the correlation among the load, and combines semi-invariant and Gram-Charlier series expansion to caculate probabilistic load flow. In this paper, operations under various conditions, the voltage fluctuations and the load of changes affected by different factors are analysed in IEEE-30 bus system.