Harmonic Minimization In Multilevel Inverters By Using PSO (original) (raw)
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so, far several methods have been presented to eliminate & minimize the low order voltage harmonics at multilevel inverter"s output & maintain the fundamental component at the desired value. This paper focus on elimination of harmonics in a cascaded H-bridge 11 level inverter. Two heuristic techniques are implemented to find out the minimum THD in cascade multilevel inverter. Using the mathematical theory of resultants, all solutions to this equivalent problem can be found. Theoretical results are verified by simulation and experiments for an 11-level H-bridge inverter. Results show that the proposed methods effectively eliminate a great number of specific harmonics, and the output voltage is resulted in low total harmonic distortion.
The use of multilevel inverters in renewable energy such as fuel cell, solar cell, and wind turbines, which use converters, is becoming more prominent. Therefore, the harmonic reduction concept in these inverters is being considered. In this paper, three algorithms (particle swarm optimization (PSO), modified particle swarm optimization (MPSO), and weight improved particle swarm optimization (WIPSO)) are used to determine the optimum switching angles of cascade multilevel inverters for obtaining minimum voltage total harmonic distortion (THD) in a wide range of modulation index. To reduce the THD, selective harmonics should be eliminated by optimal switching angles. In this paper, five switching angles of an Eleven-Level H-bridge inverter are determined by the three mentioned algorithms to reduce the voltage THD. The derived equations for the computation of output voltage THD of an inverter are used as the objective function. This objective function is used to minimize the THD in the output voltage of an inverter. While minimizing the objective function, the selective harmonics such as the 5th, 7th, 11th and 13th can be controlled by using the PSO, MPSO, and WIPSO algorithms. The simulations are performed for an 11 level cascaded multilevel inverter to show the validity of the proposed methods. The results show that all three proposed algorithms can eliminate selective harmonic in optimization problem and output voltage THD decreases. Generally, the WIPSO algorithm finds the answer with less iteration and with higher speed convergence among the proposed methods. The performance of the three mentioned algorithms for THD reduction depends on amplitude modulation index (M). MPSO and WIPSO algorithms have lower iteration numbers than PSO algorithm. Also WIPSO algorithm has higher speed convergence among the proposed methods. All three proposed algorithms reduce the 5 th , 7 th , 11 th and 13 th order harmonics in optimization problem.
Selective Harmonic Elimination of Five-level Cascaded Inverter Using Particle Swarm Optimization
This paper presents an efficient selective harmonics elimination method for a cascaded fivelevel inverter by using Particle Swarm Optimization (PSO) method. The aim of this research is to eliminate selected low-order harmonics by solving non-linear equations using the developed PSO algorithm, while at the same time the fundamental component is retained efficiently. In order to find the efficient switching angles of a five-level cascaded inverter, a PSO algorithm has been developed to solve the non-linear equations. Instead of single switching, multiple switching in a quarter cycles has been introduced to increase the number of harmonic orders that should be eliminated. With the proposed method, the required switching angles are computed efficiently by PSO in order to eliminate low-order harmonics up to the 17 th order from the inverter voltage waveform. The entire system has been simulated using PSIM software and a prototype of five-level cascaded inverter with Field Programmable Gate Array (FPGA) has been built in the laboratory. Performance of the proposed method for a five-level cascaded H-bridge inverter, based on simulation studies, is evaluated and experimentally verified.
Harmonics elimination in a multilevel inverter using the particle swarm optimisation technique
IET Power Electronics, 2009
A method is presented to compute the switching angles for selected harmonic elimination (SHE) in a multilevel inverter using the particle swarm optimisation technique. For a desired fundamental voltage, the switching angles are computed by the developed algorithm while eliminating the lower-order harmonics. Also, the selected higher-order harmonics are eliminated by additional switching to contribute minimum total harmonic distortion (THD) for the output voltage. The switching angles computed for optimum THD at varying modulation index are stored as a look-up table in digital signal processor (DSP) memory for online application, thus reducing the online computational burden of solving the non-linear equations of SHE problem. Direct solution of non-linear transcendental equations of SHE problem can lead to discontinuity at certain modulation indices. Here the switching angles are computed offline considering optimum voltage THD whereas selected harmonics are eliminated at all possible modulation indices including the point of discontinuity. The computed angles are used in an experimental setup to validate the simulated results.
International Journal of Engineering Research and Technology (IJERT), 2014
https://www.ijert.org/the-selective-harmonic-elimination-technique-for-harmonic-reduction-of-multilevel-inverter-using-pso-algorithm https://www.ijert.org/research/the-selective-harmonic-elimination-technique-for-harmonic-reduction-of-multilevel-inverter-using-pso-algorithm-IJERTV3IS20196.pdf In multilevel inverters, the Selective Harmonic Elimination (SHE) technique is the most important one. The even harmonics are absent due to quarter wave symmetry of the output voltage. For any odd harmonics, the desired value equated to zero for the harmonics to be eliminated. Nonlinear transcendental equations are thus formed and after solving those equations, α 1 through α k are computed. These nonlinear equations show multiple solutions and the main difficulty is its discontinuity at certain points where no set of solution is available. This limitation is addressed by using Particle Swarm Optimization (PSO). The objective function and the constraints are formulated as the function of switching angles. The switching angles are computed by PSO algorithm. By implementing these angles as additional switching angles per quarter cycle of the output voltage waveform, the harmonics are reduced eliminated.. The THD of the output voltage is taken as the performance measure. It is found that, PSO based switching angles greatly reduces the THD when compared with the normal switching.
Particle Swarm Optimization Approach to Harmonic Reduction in Voltage Source Multilevel Inverter
In Selective Harmonic Elimination-Pulse Width Modulation (SHE-PWM) technique, optimal switching angles at fundamental switching frequency are computed such that low order harmonics are eliminated, while the fundamental voltage is obtained as desired. The main challenge associated with SHE- PWM technique is that a specified number of transcendental nonlinear equations known as Selective Harmonic Elimination (SHE) equations have to be solved to obtain the appropriate switching angles. In this paper, Particle Swarm Optimization (PSO) algorithm with random initial values is proposed for solving SHE equations of an 11-level inverter. The proposed method is derivative-free, accurate and globally convergent. Both computational and MATLAB simulation results show that the proposed method is highly efficient for elimination of the selected low order harmonics as well as minimization of the total harmonic distortion (THD).
Using multilevel inverter in numerous applications is commonplace. Inverters supplied from equal dc source are almost rare. Although variation in dc source affects inverter switching characteristics. Solving a nonlinear transcendental equation set describing harmonic elimination with non-equal dc sources reaches the limitation of contemporary computer algebra software tools as marked in literatures. This paper presents an optimal solution for harmonic reduction namely weight improved particle swarm optimization (WIPSO ), where a set of mathematical equation describing the general output waveform for the computation of total harmonic distortion (THD) is used as the objective function and is employed to compute the optimal solution set of switching angles without knowing proper initial guess. Theoretical analysis is validated through simulations for 5, 7, 9 and 11 level cascaded multilevel inverters performed on MATLAB software. Results show a decrease in THD as level of inverter increases reflecting to approach towards a sinusoidal output voltage waveform thereby eliminating harmonics.
IEEE Transactions on Power Electronics, 2009
Harmonic minimization in multilevel inverters is a complex optimization problem that involves nonlinear transcendental equations having multiple local minima. In this paper, a solution to the harmonic minimization problem using a novel particle swarm optimization (PSO) approach based on species-based PSO (SPSO) is presented. The original SPSO is modified, which increased the robustness of algorithm to find global optimum of the search space. The proposed method is able to find the optimum switching angles when their number is increased, while it is not possible to determine them using either conventional iterative techniques or resultant theory method. Theoretical results are verified by experiments and simulations for an 11-level H-bridge inverter. Results show that the proposed method effectively minimizes a large number of specific harmonics, and the output voltage results in very low total harmonic distortion and switching frequency.
Harmonic Elimination of Hybrid Multilevel Inverters Using Particle Swarm Optimization
—This paper present the harmonic elimination of hybrid multilevel inverters (HMI) which could be increase the number of output voltage level. Total Harmonic Distortion (THD) is one of the most important requirements concerning performance indices. Because of many numbers output levels of HMI, it had numerous unknown variables of eliminate undesired individual harmonic and THD nonlinear equations set. Optimized harmonic stepped waveform (OHSW) is solving switching angles conventional method, but most complicated for solving as added level. The artificial intelligent techniques are deliberation to solve this problem. This paper presents the Particle Swarm Optimization (PSO) technique for solving switching angles to get minimum THD and eliminate undesired individual harmonics of 15-levels hybrid multilevel inverters. Consequently it had many variables and could eliminate numerous harmonics. Both advantages including high level of inverter and Particle Swarm Optimization (PSO) are used as powerful tools for harmonics elimination.
Harmonic Elimination of Multilevel Inverters Using Particle Swarm Optimization
This paper presents the novel particle swarm optimization technique to determine the optimum switching angles of multilevel converters so as to produce the required fundamental voltage while at the same time not generate lower order harmonics. This optimization method is applied to transcendental equations characterizing the harmonic content to minimize low order harmonics. All set of solutions are found for seven and eleven levels inverters to show the simplicity and effectiveness of proposed method.