To ensure the security and stable operation of the whole power system

a comprehensive evaluation of reliability of thermal power generating units for 11 power plants nationwide was carried out

combining with improvements of the conventional TOPSIS method in weight and distance.On the basis of the unit operating data in the first half of 2012 published by the ITU

the improved Eigenvector method and information entropy method were adopted to acquire and integrate the objective and subjective weights.After that

the reliability of units in these power plants was evaluated and ranked by adopting Minkowski distance as a substitution for the Euclid distance in the conventional TOPSIS method.The results show the improved TOPSIS method is a comprehensive and effective evaluation method for the power plants' operational reliability

which can provide references for the safe and stable operation of the electric power systems.