A new efficient BBO based method for simultaneous placement of inverter-based DG units and capacitors considering harmonic limits

• Optimal allocation of DGs and capacitors considering harmonic pollution is proposed.
• Objective includes power loss reduction, improving voltage profile and purchased energy reduction.
• Effect of THD constraint is investigated in the objective function.
• BBO, PSO and GA optimization algorithms is used for optimal allocation problem.
• The proposed method is applied on two types of RDS in presence of nonlinear loads.

In recent years, nonlinear load and inverter-based distributed generation (like photovoltaic and fuel cells) have been increasing rapidly. This type of DGs can amplify and propagate the harmonic level of network. Shunt capacitor banks and DG units allocation without considering harmonic limits will increase harmonic pollution. In this paper the biogeography-based optimization (BBO) algorithm is applied in simultaneous optimal sitting and sizing of inverter-based DGs and capacitor banks regarding multi-level and nonlinear loads. The objective of problem are reduction of active and reactive power loss, reduction of purchased energy from transmission line and improvement of voltage profile considering equal and unequal constrains. Also, effect of total harmonic distortion (THD) constraint according to IEEE 519 standard has been investigated in the objective function which is one of the main advantages of the proposed method. The proposed method is tested on IEEE 33 bus and IEEE 69 bus radial distribution systems (RDS). Comparing BBO method results with particle swarm optimization (PSO) and genetic algorithm (GA) results will indicate the high capability of the proposed method in simultaneously optimal sitting and sizing of DGs and capacitors.