The high penetration level of distributed generation (DG) units may lead to various problems and operational limit violations in electric power distribution systems if it exceeds a particular limit known as the system's hosting capacity (HC). In this paper, the problem of selecting the optimal conductor for a real radial distribution system in Egypt is investigated using a recent meta-heuristic algorithm, known as salp swarm optimization. First, a constrained optimization problem is introduced to minimize the combined annual cost of energy losses and the investment cost of the conductors while complying with the system voltage limits and conductor thermal capacities. The results obtained show the effectiveness of the algorithm in satisfying the objective function and constraints. However, the optimization results also show that a reduction in the size of some existing conductors should take place, although this is not allowed by the utilities because of practical reasons such as load growth, variations in loading scenarios, and the possibility of connecting DG units with uncertain penetration levels and locations. Hence, a practical feeder reinforcement approach is proposed to maintain the constraints while considering these uncertainties. Further, a novel feeder reinforcement index is proposed to assist the distribution system operators and planners to determine the feeders that first need to be reinforced. The results obtained show that the proposed reinforcement approach attains a better level of HC than can be obtained with the conventional conductor selection approach under the same testing conditions.

The high penetration of distributed generation (DG) units with their power-electronic interfaces may lead to various power quality problems, such as excessive harmonic distortions and increased non-sinusoidal power losses. In this paper, the probabilistic hosting capacity (PHC) due to the high penetration of photovoltaic units in a non-sinusoidal power distribution system is investigated. A C-type harmonic filter is proposed, to maximize the harmonic-constrained PHC. An optimization problem is formulated by using a Monte Carlo simulation, taking into account various uncertain parameters, such as the intermittent output power of the DGs, background voltage harmonics, load alteration, and the filter parameters’ variations. In addition, different operational constraints have been considered, such as the bus voltage, line thermal capacity, power factor, and individual and total harmonic distortion limits. A swarm-based, meta-heuristic optimization algorithm known as the hybrid particle swarm optimization and gravitational search algorithm (PSOGSA) has been examined for the optimal design of the proposed filter. Besides, other optimization algorithms were examined for validation of the solution. The PHC results obtained are compared with the conventional deterministic HC (DHC) results, and it is found that the PHC levels are higher than those obtained by conservative HC procedures, practical rules of thumb, and the DHC approaches.