Wide range modulation indexes featuring carrier-based PWM stepped waveform for half-bridge modular multilevel converters

This paper presents simulation results of the influence of wide range modulation index values ( a m ) in carrier-based PWM strategy for application in generating the stepped waveform. The waveform is tested for application in single-phase half-bridge modular multilevel converters (MMCs) topology. The results presented in this paper include a variation of the fundamental component (50 Hz) in the voltage output. It also studies total harmonic distortion of the output voltage (THDv) and the output current (THDi) when the modulation index is changed over the linear-modulation region, 0 < a m < 1. It also explores the effect of a modulation index greater than 1. Moreover, different output voltage shapes, as a consequence of varied a m on MMCs, are also illustrated for showing the effect of varying the value of a m on sub-module of MMC's. *********************************************************** Kajian ini berkenaan tentang pengaruh simulasi terhadap pelbagai nilai indeks ( ) berasaskan strategi PWM bagi menghasilkan bentuk gelombang bertingkat. Bentuk gelombang ini diuji untuk aplikasi topologi MMCs. Keputusan menunjukkan variasi pada komponen asas (50Hz) pada voltan akhir. Keputusan menunjukkan jumlah penyelarasan harmonik voltan akhir (THDv) dan arus (THDv) apabila indeks modulasi telah ditukar pada had modulasi linear, 0 < < 1. Ia juga membincangkan tentang kesan indeks modulasi lebih daripada 1. Selain itu, bentuk voltan akhir yang berbeza mengikut perubahan nilai pada MMCs juga dilampirkan bagi menunjukkan kesan perbezaan nilai pada sub-modul MMCs

WIDE RANGE MODULATION INDEXES FEATURED CARRIER-BASED PWM STEPPED WAVEFORM FOR HALF-BRIDGE MODULAR MULTILEVEL CONVERTERS

ABSTRACT: This paper presents simulation results of the influence of wide range modulation index values ( ) in carrier-based PWM strategy for application in generating the stepped waveform. The waveform is tested for application in single-phase half-bridge modular multilevel converters (MMCs) topology. The results presented in this paper include a variation of the fundamental component (50 Hz) in the voltage output.  It also studies total harmonic distortion of the output voltage (THDv) and the output current (THDi) when the modulation index is changed over the linear-modulation region, 0 < < 1. It also explores the effect of a modulation index greater than 1. Moreover, different output voltage shapes, as a consequence of varied  on MMCs, are also illustrated for showing the effect of varying the value of on sub-module of MMCs. ABSTRAK: Kajian ini berkenaan tentang pengaruh simulasi terhadap pelbagai nilai indeks ( ) berasaskan strategi PWM bagi menghasilkan bentuk gelombang bertingkat. Bentuk gelombang ini diuji untuk aplikasi topologi MMCs. Keputusan menunjukkan variasi pada komponen asas (50Hz) pada voltan akhir. Keputusan menunjukkan jumlah penyelarasan harmonik voltan akhir (THDv) dan arus (THDv) apabila indeks modulasi telah ditukar pada had modulasi linear, 0 < < 1. Ia juga membincangkan tentang kesan indeks modulasi lebih daripada 1. Selain itu, bentuk voltan akhir yang berbeza mengikut perubahan nilai   pada MMCs juga dilampirkan bagi menunjukkan kesan perbezaan nilai    pada sub-modul MMCs

Harmonics elimination based on curve fitting method for modular multilevel converters

This paper presents the additional ways to figure out the switching angles for eliminating harmonic in Modular Multilevel Converters, MMCs. The switching angles equation is written in terms of nonlinear equation system, in general, one of the numerical method, named Newton-Raphson method, is used for this calculation procedure but the Newton-Raphson method takes more time for calculation that is difficult to implement the MMCs in a real-time control application. So that, numerous previous calculation methods are proposed to address this issue. To reduce the calculated time of switching angles, the Curve Fitting method is selected to assist the Newton-Raphson method and the idea of this combination method is presented in this paper. The calculation result of this combination and original Newton-Raphson method are compared and implemented in the 3-phase 7-level MMCs simulation to validate the calculation results. The Curve-Fitting can be used for calculation assisting of Newton-Raphson Method and obtains the calculation results faster than the using of lone Newton-Raphson method

Integrated renewable energy micro-grid for meeting peak hours demand

In the TNB-based conventional system, the power demand varies randomly depending upon seasons and months of the year including festive occasions, reaching peak in some hours of days of some months. Sometime a heavy demand (in MW) falls at a time of a day. Such heavy energy demands need to be transported from far-away power stations over long lengthy transmissions causing energy loss not less than 20% in most of the cases. This paper presents load demand variation scenario, identifying peaks, and finally suggesting a strategy for meeting the peak demand from Renewable Energy Sources (RES) of solar and wind. An integrated RES-based microgrid is suggested with analytical and simulation results showing how the peak demand is being met from alternative sources of solar. The results of this paper find applications in suggesting RES-based generations for distributed locations within the low-voltage distribution network of Malaysian Electric Utility Tenaga Nasional Berhad

Predictive control of AC/AC matrix converter

This work investigates the usage of Model Predictive Control (MPC) for a three phase conventional matrix converter with low pass filter at the input and output side. The conventional matrix converter has 3 input and 3 output which gives 27 switching state. From this design, a MPC is incorporate to control the output voltage and the input currents for all the phases. The design of the proposed controller is based on the input current controller and output voltage controller with load observer. The proposed MPC using cost function will select the minimized switching state to be applied to next switching. This gives a sinusoidal output voltages and input currents. A simulation and experimental studies are presented to validate the proposed control scheme

Input-series output-parallel full-bridge DC-DC converter for high power applications

Input-series and output-parallel (ISOP) connected DC-DC converters are suitable for high input voltage and high output current applications by using a low voltage rating power switches. This paper proposes an input-series-output-parallel Full-Bridge DC-DC converter with low-voltage switches under high frequency operation with low losses switching, low harmonic spikes with high efficiency and high power density. In this proposed work, Arduino mega microcontroller has been used to generate Pulse Width Modulation (PWM) for ISOP configuration. Under different duty cycle PWM and switching frequency, the simulation and experimental results with appropriate theoretical analysis of an ISOP full-bridge converter topology are presented

On quality energy management in a third world country: the case study of war torn Libya

The ever growing energy demands and the negative environmental impacts associated with global warming have pushed the policy makers toward adopting renewable energy sources. Unfortunately, the management of energy resources in many countries still fall short of optimizing the depleting nature of conventional energy sources and balancing them with untapped and abundant renewable energy sources. This calls for a detailed study on quality management of energy with the objective of minimizing losses and capitalizing on more efficient conversion methods of energy transfer for use in important industry applications. A good case study is in war torn country like Libya. Libya is one of the countries that recently struggles to satisfy its energy demand, although, the country has a high potential for solar energy. One major sector is electricity generation, which uses gas and fuel-fire to operate the turbines in the generation stations. Libya currently produces 33 TWH of energy to meet the demand of the local electricity market. The demand on energy will substantially increase in the near future as a result of economic development in order to build new infrastructure in Libya after the massive destruction that happened during the last four years. This will lead to more consumption of oil and gas, which causes a reduction in the national economical revenues, and more carbon dioxide emission. Therefore, Libya should use its alternative energy supplies to cover some of its load requirements. In this paper, we investigate the current energy situation in Libya while exploring the use of renewable energy to improve the current poor situation through some example scenarios. A quality management program of the energy landscape may be necessary as a way forward for the country to sustain any form of economic development amidst the shortage of energy resources in the country

Modulation indices embedded carrier-based PWM generation for modular multilevel converter

The fundamental component (50Hz) in the output voltage of a single-phase modular multilevel converter (MMC) can be diverted by varying of the value of modulation index (Mi). However, this changing affects on the value of the total harmonic distortion of the output voltage (THDv) and output current (THDi). Moreover, the variableness of modulation index can be differentiated to be linear region and over-modulation region to consider the correlation of modulation indices and fundamental component, and THD. Each region has a different effect on THDv and THDi. To facilitate, this paper demonstrations the results of carrier-based PWM strategy simulation in a singlephase 7-level MMC with a single-phase induction motor as a load to study the behavior of THDv and THDi when the modulation index value is changed

Selective harmonics elimination technique in single phase unipolar H -bridge inverter

Specific odd harmonics can be mitigated by operating the semiconductor switches in H-bridge inverters at optimized switching angles of the PWM signals. These switching angles can be achieved by deriving a set of nonlinear equations using Selective Harmonic Elimination Pulse Width Modulation (SHE-PWM) technique. Modulation index (ma) is a significant parameter used to control the amplitude of the fundamental output voltage of DC-AC inverter. By changing the value of modulation index the Total Harmonics Distortion (THD) also will change. In this paper, the performance of single phase H-bridge inverter using SHE-PWM scheme with varying the modulation index is evaluated. In order to achieve a minimum THD, a different number of nonlinear equations are used to calculate the switching angles. The performance of a single phase H-bridge inverter is simulated in Matlab-Simulink