One of the most important aims of the sizing and allocation of distributed generators (DGs) in power systems is to achieve the highest feasible efficiency and performance by using the least number of DGs. Considering the use of two DGs in comparison to a single DG significantly increases the degree of freedom in designing the power system. In this paper, the optimal placement and sizing of two DGs in the standard IEEE 33-bus network have been investigated with three objective functions which are the reduction of network losses, the improvement of voltage profiles, and cost reduction. In this way, by using the backward-forward load distribution, the load distribution is performed on the 33-bus network with the power summation method to obtain the total system losses and the average bus voltage. Then, using the iterative search algorithm and considering problem constraints, placement and sizing are done for two DGs to obtain all the possible answers and next, among these answers three answers are extracted as the best answers through three methods of fuzzy logic, the weighted sum, and the shortest distance from the origin. Also, using the multi-objective non-dominated sorting genetic algorithm II (NSGA-II) and setting the algorithm parameters, thirty-six Pareto fronts are obtained and from each Pareto front, with the help of three methods of fuzzy logic, weighted sum, and the shortest distance from the origin, three answers are extracted as the best answers. Finally, the answer which shows the least difference among the responses of the iterative search algorithm is selected as the best answer. The simulation results verify the performance and efficiency of the proposed method.
In this paper, an independent wind energy conversion system was studied with the control strategies used to provide power specifically to the areas far from the grid. In this research, three strategies are designed and used in order to stabilize the output. This system contains a directed rectifier which is responsible for maximum power point tracking. Additionally, a common DC bus and a fully controlled inverter were designed. An LC filter was also used in the system in order to eliminate switching harmonics to a considerable extent and provide a reliable noiseless source for load supply. Since the power demand and the produced power of the turbine are variable and indistinguishable in each moment, a depletion load is also placed in the system. In this study, it was observed that the designed strategies prove the output stability in different sections and under different conditions with resonators and non-linear PI and PID controllers. The designed strategies were also supported by the simulation results.
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