Utilization of active power filters (APFs) is the most efficient method to reduce harmonic pollution in distribution networks. Previous approaches utilized APFs in integrated control schemes based on broad data-gathering systems. Since a broad data-gathering system is not available in most practical distribution networks, previously proposed approaches may not readily be implemented. This paper presents the utilization of stand-alone controlled APFs (SACAPFs) in radial distribution networks. Utilizing APFs with a stand-alone control system decreases implementation costs and complexity by making them autonomous and independent of integrated control systems, which are complicated and expensive in practical applications. In this paper, a single SACAPF is modeled as a dependent current source where its injection current is equal in amplitude but opposite in phase compared to the harmonic content of the current passing through the point of common coupling (reference current). Due to the presence of both linear and nonlinear loads in the distribution network, the reference current changes after injection by SACAPF, so it is necessary to modify the injection current until reaching a constant value in the reference current. This is considered via an iterative procedure in the modeling scheme. Operation of multiple SACAPFs is handled using a backward procedure based on a priority list. Simulation results on an IEEE 18-bus test system show the proper operation of the stand-alone control systems for both single and multiple SACAPF implementation. Furthermore, optimal allocation of the proposed SACAPFs is performed in an IEEE 33-bus test network and a 9-bus test network, and the results are discussed and compared with the allocation of integrated control system APFs.

Recently, Power Quality is attracting the attention of researchers focused on distribution network reconfiguration. Mainly, harmonic distortion as an emerging issue of distribution networks plays an essential role in power quality-oriented network reconfiguration. Commonly, harmonic analysis of distribution networks is being performed while considering non-linear loads, capacitor banks, sub-transmission transformers, and line impedances. However, in harmonic analysis, the presence of linear loads and their effects are being neglected. Consideration of linear loads in harmonic analysis affects the impedance characteristic of the distribution network. Consequently, it changes the total harmonic distortion of bus voltages. In this paper, for the first time, exhaustive research is performed on the effect of linear loads in distribution network reconfiguration by considering five conventional linear load models. The evaluations are conducted on two balanced and unbalanced distribution networks: IEEE 69-bus and 95-bus practical Iranian distribution network using particle swarm optimization aiming to find the minimum total losses of the network. Comparison results confirm that the linear load modelling is very effective in the optimum configuration.