Research Of Probabilistic Load Flow For Power Grid Containing Wind Farms

In recent years, because of the development of new energy power generationtechnologies, particularly the large-scale application of wind power technology, and becauseof wind power technology itself random characteristics, the safe and stable operation of thepower grid soon meet a new problem. Especially after the large-scale wind farms connected tothe power system, the impact on safe and stable operation of the power grid is more obvious.Adding some uncertainties affecting the power system such as generator power output, loadchanges, line fault etc. bring new problems in power flow calculation. Ideas and methods ofcommon power flow calculation can not suit the new requirements, considering theprobability of random factors affecting the calculation of trend analysis methods have beendeveloped and applied.Probabilistic load flow calculation is the combination of probability theory and thepower flow calculation, using probability theory to analyze the load flow of power system.The common power flow calculation can get the exact value of voltage and the power,however, probabilistic load flow calculation method can give the characteristics of probabilityand statistics of power system voltage and power distribution, analysis the probability and theexpected probability of node voltage and branch power probability in some range usingprobability statistical perspective. This has important implications for the power systemplanning and design and stability assessment.In the probabilistic load flow calculation, the network topology system is usuallyassumed unchanged, and the branch is independent of each other. Although such treatmentscan simplify calculation, the results have a certain error. Because of the influences of variousfactors of the actual power system, and the branch of external or self generated random failure,caused the change of network topology; and branch fault caused impact to other branch powerflow distribution. A certain correlation exists between each other, and are not independent ofeach other. Therefore, in the probabilistic load flow calculation, the correlation factorsbetween the network topology changing and branch should be considered, in order to morecomprehensivly and accuraly reflect the actual operation of power system.This thesis aiming at the actual situation that large-scale wind farms connected to thepower system, established the probability model of wind power generator. Based on theprobabilistic load flow calculation, the probabilistic load flow calculation model consideringthe system network topology changes and the of branch correlation factors is established.Application of Matlab simulation software analysis the influence between the network topology and branch correlation factors on power system node voltage and branch power..