Hybrid optimization algorithm applied for selective harmonic elimination in multilevel inverter with reduced switch topology (original) (raw)
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ANT COLONY OPTIMISATION APPROACH TO SELECTIVE HARMONIC ELIMINATION IN MULTILEVEL INVERTER
In Selective Harmonic Elimination-Pulse Width Modulation (SHE-PWM) method, low order harmonics are eliminated, while the fundamental harmonic is obtained at the desired value. In this paper, Variable Sampling Ant Colony Optimization (SamACO) algorithm with random initial values is proposed for solving the transcendental nonlinear equations known as Selective Harmonic Elimination (SHE) equations that characterize the selected harmonics in an 11- level inverter. The algorithm is a continuous (combinatorial) optimization algorithm that is based on the food foraging behavior of ants in a swarm. The dynamic exploitation and random exploration operators in the algorithm ensure both accuracy and convergence to global optima. Fast Fourier Transform (FFT) analysis of the synthesized voltage waveform th th th th reveals the complete elimination of the 5 ,7 ,11 and13 harmonics as their values tend towards zero. 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).
This paper presents a novel two-phase hybrid optimization algorithm called Real Coded Genetic Algorithm Initialized Newton Raphson (GAIN) method for solving the transcendental nonlinear equations characterizing harmonics in multilevel converters. The proposed hybrid Real GAIN method is developed in such a way that Real Coded Genetic Algorithm (RCGA) is the primary optimizer exploiting its global search capabilities by directing the search towards the optimal region, and Newton Raphson method is then employed as a local search method to fine tune the best solution provided by RCGA in each evolution. The proposed method is implemented for the offline computation of the optimum switching angles in an 11-level inverter so that the required fundamental voltage is produced while the low order harmonics specifically the 5th, 7th, 11th and 13th harmonics which are more harmful and more difficult to remove with filters are eliminated. Computational and MATLAB simulation results clearly demonstrate the effectiveness and high spectral performance of the proposed algorithm.
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. In this paper, ant colony optimization (ACO), particle swarm optimization (PSO), and real coded genetic algorithm (RCGA) were implemented and compared for solving selective harmonic elimination (SHE) equations of an 11-level inverter. Using the same population size and the same step size of modulation index, performance evaluations of the three methods show that PSO is the fastest, RCGA are is the most efficient in terms of low order harmonic elimination while ACO is the most efficient in terms of minimization of total harmonic distortion (THD) over a wide range of modulation indices. Computational results are validated with MATLAB simulations.
International Journal of Engineering Research and Technology (IJERT), 2013
https://www.ijert.org/selective-harmonic-elimination-in-multilevel-inverter-using-real-coded-genetic-algorithm-initialized-newton-raphson-method https://www.ijert.org/research/selective-harmonic-elimination-in-multilevel-inverter-using-real-coded-genetic-algorithm-initialized-newton-raphson-method-IJERTV2IS90907.pdf This paper presents a novel two-phase hybrid optimization algorithm called Real Coded Genetic Algorithm Initialized Newton Raphson (GAIN) method for solving the transcendental nonlinear equations characterizing harmonics in multilevel converters. The proposed hybrid Real GAIN method is developed in such a way that Real Coded Genetic Algorithm (RCGA) is the primary optimizer exploiting its global search capabilities by directing the search towards the optimal region, and Newton Raphson method is then employed as a local search method to fine tune the best solution provided by RCGA in each evolution. The proposed method is implemented for the offline computation of the optimum switching angles in an 11-level inverter so that the required fundamental voltage is produced while the low order harmonics specifically the 5 th , 7 th , 11 th and 13 th harmonics which are more harmful and more difficult to remove with filters are eliminated. Computational and MATLAB simulation results clearly demonstrate the effectiveness and high spectral performance of the proposed algorithm.
Application of Newton Raphson Method for Selective Harmonic Elimination in Multilevel Inverter
2014
Multilevel inverters have been important devices developed in recent years, owing to their capability to increase the voltage and power delivered to the load. Researches done based on basic inverter topologies shows that, Multilevel inverters have been widely used in medium and high-voltage applications as they have many advantages such as low power dissipation on power switches, low harmonic and low electromagnetic interference (EMI) outputs. For getting the improvement in inverter performance and quality of output, the different methods has been implemented such as, use of various switching strategies, use of Low Pass Filter to eliminate higher order harmonics ,use of Multilevel Structure in order to reduce harmonics and THD. The Selective harmonic elimination method for the staircase voltage waveform generated by multilevel inverter has been studied extensively in the last decade. The selective harmonic elimination method for 3-Pahase 7-Level Multilevel inverter using simple PWM ...
IET Power Electronics, 2018
Multilevel inverters (MLIs) are nowadays extensively used in integration with renewable energy sources and in drives applications. The converter cost and voltage quality improvement are the utmost importance in such application of MLI. A sixswitch seven-level reduced switch symmetrical MLI (6S-7L MLI) is proposed here. Compared to the conventional and similar existing MLI topologies, the proposed MLI uses less active switches and has less driver circuit requirement. A particle swarm optimisation (PSO)-based modified selected harmonic elimination technique is derived and analysed for computing optimal switching angles of proposed 6S-7L MLI to eliminate third-and fifth-order harmonics. Moreover, the performance of the proposed algorithm is compared with the two most commonly used PSO variants. The analysis shows the modified version of PSO is most suitable for optimising the output voltage of proposed MLI through targeted harmonic elimination. The proposed topology is investigated through simulation by applying the calculated switching angles using modified PSO algorithm. Finally, a single-phase experimental prototype is designed to verify the validity of the proposed structure.
Electronics
Multilevel inverters (MLI) are popular in high-power applications. MLIs are generally configured to have switches reduced by switching techniques that eliminate low-order harmonics. The selective harmonic elimination (SHE) method, which significantly reduces the number of switching, determines the optimal switching moments to obtain the desired output voltage and eliminates the desired harmonic components. To solve the SHE problem, classical methods are primarily employed. The disadvantages of such methods are the high probability of trapping in locally optimal solutions and their dependence on initial controlling parameters. One solution to overcome this problem is the use of metaheuristic algorithms. In this study, firstly, 22 metaheuristic algorithms with different sources of inspiration were used to solve the SHE problem at different levels of MLIs, and their performances were extensively analyzed. To reveal the method that offers the best solution, these algorithms were first a...
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.
This paper represents the reduction of harmonics in a cascade H-bridge multilevel inverter using iterative newton-raphson (NR) and genetic algorithm (GA) techniques. The proposed optimization techniques are used to solve the set of non-linear transcendental trigonometrical equations. The controlling pulses are obtained by harmonic elimination pulse width modulation (SHE-PWM) switching method. The set of non-linear transcendental equation is minimized by proposed iterative newton-raphson (NR) and genetic algorithm (GA) techniques, and also have been analysed and compared the harmonics.
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.