In the modern industry, most of the equipment use semiconductor devices and microprocessors which are sensitive against power disturbances. Among power disturbances, voltage sags are considered as the most frequent type of disturbances in the field and their impact on sensitive loads is severe. However, to assess voltage sags, installation of power quality monitors (PQM) at all system buses is not economical. Thus, this study is carried out to develop a power quality monitor positioning algorithm to find the optimal number and placement of PQMs in both transmission and distribution systems. In this approach, first, the concept of topological monitor reach area is introduced. Then the binary particle swarm optimization hybridized with artificial immune system is used to solve multi-objective function in finding the optimal placement of PQMs. The proposed algorithm has been implemented and tested on the IEEE 30-bus and the 69-bus test systems to show the effectiveness of the proposed method for both transmission and distribution systems.