Power quality monitor placement in power systems considering channel limits and estimation error at unobservable buses using a bi-level approach

The aim of this paper is to propose a new method for locating power quality monitors (PQMs) in a power system at different depths of unobservability. In this method, the placement problem is solved in two levels, taking into account the limitation on the number of measuring channels of these devices. At the first level of this method, different combinations of connecting lines are selected, while the second level determines the best location of monitors for each combination, at different unobservability depths. In addition, the second level also identifies the critical buses and considers their effects on the number and location of monitors. The proposed method also minimizes the voltage phasor estimation error at unobservable buses as well as the cost of these devices as the main objectives. Therefore, this method will find the best location for installing monitors and the minimum number of channels required by these devices to make all power quality parameters, i.e. voltage and current phasors, observable. The results of applying the new method on IEEE 14-bus and IEEE 30-bus power systems and the Iranian south east regional grid (ISERG) demonstrates the performance of proposed method.