By applying hidden Markov model(HMM) to the aggregate load and interior equipment,the nonintrusive load monitoring(NILM)problem can be described as the decoding of HMM and solved by Viterbi algorithm. However, in the case of a larger number of equipment or equipment states,Viterbi algorithm is not applicable to solving the NILM problem due to a long execution time. For this reason,Viterbi
... [Show full abstract] algorithm is modified. Since the equipment states remain the same between two consecutive load events,the number of state sequences that need to be traversed by Viterbi algo-rithm is reduced considering that the equipment states will not change until a load event occurs. Compared with the stan-dard Viterbi algorithm,the modified version can reduce the execution time and it is applicable to the case of a larger number of equipment or equipment states. Results of case studies show the effectiveness of the modified Viterbi algo-rithm.