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A surface area of 1085.92 m2/g and a monolayer adsorption capacity of 497.66 mg/g were obtained from the optimum activated carbon derived using Prosopis africana seed hulls (PASH-AC) at the activation temperature of 795°C, activation time of 62 minutes, and impregnation ratio of 2.45. Five different forms of the linearized Langmuir equations along with two other models (Freundlich and Temkin) were tested on the adsorption data. The best adsorption model was selected using correlation coefficient (R2) and chi-square (χ2) was used for assessing the validity of each isotherm model. Langmuir-2 along and pseudo-second-order models were found to be the most suitable model for describing the equilibrium and kinetic processes, respectively.

Various meta-heuristic approaches have been developed to find the optimal solution to optimization problems. However, different approach takes different amount of time and efficiency to achieve the optimal solution. Determination of high performance and lower computing time with simple algorithm is therefore continuously established. Shark Smell Optimization (SSO) algorithm has been proven to have high efficiency in many optimization applications. However, like the other swarm intelligence, SSO algorithm also has possibility to get trapped in local maxima or premature convergence. Thus, a new adaptive shark smell optimization (ASSO) is proposed to improve the convergence efficiency of standard SSO algorithm. An overview and performance comparison of six well-known meta-heuristic optimization algorithm is also presented in this paper. In order to verify the effectiveness of this newly developed method, the algorithm was tested on common benchmark functions used in the literature. Numerical results indicate that the ASSO algorithm strategy outperforms the basic SSO algorithm, Genertic Algorithm (GA), Particle Swarm Intelligence (PSO), Firefly Algorithm (FA), Artificial Bee Colony (ABC) and Teaching Learning Based Optimization (TBLO) in term of reaching for global solution.

This paper presents the design and development of a switching controller using a field programmable gate array (FPGA)for a multilevel inverter application. SHE with PSO switching strategy was chosen and pre-calculated offline to obtain optimized switching angles for the power switches in the 5-level transistor-clamped H-bridge (TCHB) multilevel inverter. The designed switching controller produced 5-bit control signals, which connected to the power switches of the 5-level TCHB multilevel inverter. The switching controller utilized less than 1% of the total FPGA logic elements (LEs), which was equivalent to 96 out of 114,480 LEs. The execution speed of the switching controller using the FPGA chip was found to be 99.9% faster than microcontroller (PIC16F877A). Conducted simulation and measurement results verified and validated the switching controller design functionality and requirement. Keywords : multilevel inverter, switching controller; FPGA, general purpose processor (GPP);digital signal processing (DSP); IGBT; Verilog, power consumption; harmonic elimination (SHE).

In the dual-power PV-grid system, the PV-battery system and grid system are operated alternately during the on-demand and off-demand period. Power converter in the system is used to boost, regulate and convert DC sources from PV to AC. Multilevel inverter is desirable in the PV energy system owing to its capability of synthesizing ‘stepped’ AC output from several DC sources. The structure allows the inverter to reach high voltages with low harmonic and low component ratings. However, the main drawbacks of this type of inverter may include high number of power switches in the circuit, voltage balancing problem and it only operates when the sum of the input DC voltages is higher than the amplitude of the grid voltage at all the time. This chapter explains and discusses the design of power converter in the dual-power PV-grid system utilizing 21-level cascaded H-bridge multilevel inverter. Five PV strings of separate DC sources are cascaded to produce the 21-level H-bridge cascaded multilevel inverter. Low-frequency optimized switching angles of selective harmonic elimination (SHE) switching technique is chosen to minimize harmonic contents and switching losses in the inverter output. The simulation analysis of the proposed inverter recorded total harmonics distortion of 3.94%.

The Dual-power PV-grid energy system was initiated to reduce the capital installation cost of PV energy system and to make use the lower tariff rate offered at off-peak period. In this paper, the system configuration, architecture and operation of the system are described and discussed. The prototype has been developed and runs 24-hours to supply the load. Meteorological and electrical data collected prove the successful of such system. The system is expected to reduce 89% of electricity bill with estimated cost of energy (COE) of USD1.15/kWh. It is suggested that the dual-power PV-grid system is beneficial to serve as an alternative implementation of the off-grid PV energy system.

This paper presents a simulation and laboratory test of Photovoltaic (PV) module incorporated with Positive Output (PO) Buck-Boost Converter for harnessing maximum energy from the solar PV module. The main intention is to invent a system which can harvest maximum power point (MPP) energy of the PV system in string-connection. The model-based design of the controller and maximum power point tracking (MPPT) algorithm for the system were implemented using MATLAB SIMULINK software. For laboratory execution, the digital microcontroller of dsPIC30F digital signal controller (DSC) was used to control the prototype of PO buck-boost converter. The code generation via MPLAB Integrated Development Environment (IDE) from model-based design was embedded into the dsPIC30F using the SKds40A target board and PICkit 3 circuit debugger. The system was successfully simulated and verified by simulation and laboratory evaluations. A physical two PV module of PV-MF120EC3 Mitsubishi Electric is modeled in string connection to represent a mismatch module. While in laboratory process, a string-connection of 10W and 5W PV module is implemented for the mismatch module condition.

The dual-power PV-grid system was introduced to manipulate the lower tariff rate at off-peak period and to reduce the capital installation cost of PV energy system. The power converter in the PV energy system is used to process solar energy captured by PV modules into usable electrical energy. In the dual-power PV-grid system, the power converter component is consists of a boost regulator to boost and regulate PV outputs to fixed voltage of 240V, 50Hz, a maximum power point tracker (MPPT) to derive maximum power from PV panels and a three operation modes of the battery converter to regulate charging current/discharging current under various PV output and load variation. In this project, a reduced switch and increased level of cascaded H-bridge multilevel inverter was introduced to convert the direct current (DC) output of the solar energy to alternating current (AC) signal to supply an AC load or to be integrated to the grid system. By adapting selective harmonic elimination (SHE) switching strategy, the inverter produces 21 levels of stepped sinusoidal output signal with resultant total harmonics distortion (THD) of 3.90%.

This paper propose distributed fast maximum power point tracking (DFMPPT) technique to achieve maximum power point tracking (MPPT). This paper implements the algorithm in distributed MPPT (DMPPT) architecture for mismatched condition with single module, and string connection. The MPPT method uses indirect and direct MPPT method by fractional open-circuit voltage (FOCV) with incremental conductance (INC) for high-speed maximum energy harvesting. This method is proven to be fast for tracking maximum power point (MPP) which achieves the peak power less in 1.7ms via for a single module with efficiency of 99.7% compared to the recent MPPT technique to reach MPP in 1.75ms with 95.8% efficiency. While for string configuration, the efficiency of the whole system is rated by 85.583% by taking 8.675ms to reach global MPP.

This paper discussed the latest development of single-phase single stage current source inverters for grid connected photovoltaic system. In general, the single-phase single stage inverters are categorized into four types of topologies: 1) H-Bridge, 2) buck-boost, 3) flyback type chopper and 4) Z-Source inverter. The inverters are compared and evaluated on switching technique, switching frequency, efficiency, output power, MPPT method, power factor and THD.

Dual-power PV-grid system was introduced to manipulate the lower tariff rate at off-peak period and to reduce the capital installation cost of PV energy system. The power converter system consists of a boost regulator to boost and regulate PV outputs to fixed voltage of 240V, 50Hz, a maximum power point tracking (MPPT) to derive maximum power from PV panels and a three operation modes of the battery converter to regulate charging current/discharging current under various PV output and load variation. The system utilizes 25 levels of cascaded multilevel inverter to invert DC voltage from solar panel to AC voltage. The operation and the synchronization of the power converter system was digitally controlled to ensure the system works at maximum captured power, fast switching with minimum losses, and produces fixed 240 V, 50Hz power supply in variation of environmental conditions. In this paper, the control strategy implemented in the power converter system in the dual-power PV-grid energy system are described and discussed.

Dual-power PV-grid system was introduced to manipulate the lower tariff rate at off-peak period and to reduce the capital installation cost of PV energy system. In this paper, the system and simulation design of the system is discussed to evaluate the design parameters which affect the design performance of the power converter. It consists of a boost regulator to boost and regulate PV outputs to fixed voltage of 240V, 50Hz, a MPPT to derive maximum power from PV panels and a three operation modes of the battery converter to regulate charging current/discharging current under various PV output and load variation. The system utilizes 15 levels of cascaded multilevel inverter to invert DC voltage from solar panel to AC voltage. The simulation results certify the simulation model can emulate the real system.

Dual-power PV-grid system was introduced to manipulate the lower tariff rate at off-peak period and to reduce the capital installation cost of PV energy system. In this paper, the system configuration, architecture and operation of the dual-power PV energy system are described and discussed. From the review of various multilevel inverter topologies and switching control strategies, the cascaded H-bridge utilizing sinusoidal pulse width modulation (SPWM) or closed loop current control has been identified as the most appropriate inverter topology and control scheme for the system.

Dual-tariff PV energy system was introduced to maneuver the lower tariff rate at off-peak period and to reduce the capital installation cost of PV energy system. In this paper, the system configuration, architecture and operation of the dual-tariff PV energy system are described and discussed. A 2.4 kW prototype system has been developed and run 24-hours to supply the load. Meteorological and electrical data was collected and prove the successful of such system. The system is expected to reduce 89% of electricity bill with estimated COE of RM3.813/kWh. It is hoped that the dual-tariff PV system can serve as an alternative implementation of standalone PV energy system.

This paper presents studies on control electronics implementation of single-phase matrix converter operating as AC-DC converter with active power filter. The control electronics uses discrete integrated circuits (ICs) for analogue control whilst the peripheral interface controller (PIC) for digital control implementation. Comparisons are made on the performance with selected simulation and experimental results, to verify proposed operation.