Optimal Harmonic Measuring Device Placement in Distribution Networks in Consideration of Topology Changes

As effective measures of energy savings and emission reduction, non-linear loads, such as variable-frequency drives, are widely used. However, the problem of harmonic pollution in power systems is becoming increasingly severe. A harmonic on-line monitoring system is required for statistically analyzing the harmonic distribution rule in a power network and for taking harmonic suppression measures. For solving the frequent topology adjustment issue in practical distribution networks, a new observability analysis method is proposed. The probability of a switch having a closed status is used to express the nodal observability degree in consideration of network topology changes. The condition number of the measurement matrix is used as the index for estimating the precision of the harmonic state. An optimal placement model of harmonic measuring devices is presented, which considers the system observability and the condition number of the measurement matrix. The genetic algorithm (GA) is improved to solve the optimal model. A simulation model is developed based on the improved IEEE33-node system. The simulation results demonstrate the validity of the optimal harmonic measuring device placement model in distribution networks.