Comparative Study on Reliability Assessment Methods for Medium Voltage Distribution Network

The features of reliability assessment for medium-voltage distribution network are pointed out and the definition of complex distribution network is given, the present situation of the research on reliability assessment of distribution network is presented as well. In the aspect of network connectivity analysis, several commonly used analytical methods are analyzed and compared, and these methods are divided into the methods oriented to load points, components, protective devices and the equivalence based mixed method. For the method oriented to load points, the scale of the system is too large and the time-consuming is too long due to the fact that it is necessary for each load point to carry out once of topological analysis of the network; as for the method oriented to components, in spite of the fact that the principle of its main method, namely the failure mode effects analysis(FMEA), is simple, it only suits to simple and radial network; as for the method oriented to protective devices, general failure spreading method can be used to complex distribution network, however it is necessary to carry out once of topological analysis of network for each protection failure event or network partitioning, thus the algorithm is complex and time-consuming. Using the equivalence based mixed method the calculation speed can be accelerated, however the features of original methods are still reserved. Finally, the items in current reliability assessment methods to be researched and improved are pointed out.