This letter presents for the first time the application of multilevel dc-link inverter to overcome the problem of partial shading of individual photovoltaic (PV) sources which are connected in series. The "PV permutation algorithm," as a new method, is developed for the control of the inverter so as to extract the maximum power form each PV source under partial shading and to deliver all that power to the load. The algorithm is based on combination of the direct pulsewidth modulation, the sequential permutation PV sources, and the output generation to control the multilevel dc-link inverter. The algorithm is applied successfully to a seven-level inverter with separate maximum power point tracking algorithm for each PV source and under nonuniform irradiance (partial shading). Digital processing unit F28335 eZdsp is used to control the PV system in the real-time mode, and MATLAB-Simulink real-time data exchange is employed to display the extracted power and to control the system parameters via a designed graphical user interface window. The implementation and experimental results are presented.Index Terms-Maximum power point tracking (MPPT), multilevel inverter, photovoltaic partial shading, real-time data exchange (RTDX).

This paper describes a new algorithm for optimal control of a PV system under partial shading. A multilevel DC-link is the essential part of the proposed system and its control engages a voltage-hold perturbation and observation (VH-P&O) method combined with a PWM algorithm with permutation of PV sources. The algorithm enables achieving the maximum power generation for any number of PV and converter modules. The main features of the control are: (i) a continual operation of all PV sources, shaded and non-shaded, at their maximum power points, (ii) delivery of all extracted power from PV sources to the load and (iii) generation of multilevel output voltage waveform with a low total harmonic distortion.

In this paper, a new digital PWM algorithm for three phase power inverter is proposed. IPWM algorithm is based on the integration calculation of the reference signal and then converted into a square wave with variable duty cycle, in such manner that the area of the square wave equals to the integrated area of the reference waveform. The proposed algorithm is implemented practically using the M68000 microprocessor, the inverter is loaded by means of two types of loads, the first is resistive load and the second is a three phase induction motor. The obtained results are verified by comparison with the most known methods: sinusoidal PWM as analog method and space vector PWM as a digital one. The algorithm gives very satisfied results according to the inverter criterions.

The paper describes application of a multi-level DC-link converter in overcoming the problem of partially shaded series-connected PV sources. The converter control engages a permutation algorithm which enables each PV source of the string to produce the maximum power. The main features of the system are: (i) a continual operation of all PV sources, shaded and non-shaded, at their maximum power points, (ii) delivery of all extracted power from PV sources to the load and (ii) generation of multi-level output voltage waveform with a low total harmonic distortion.

Earthworms are a type of invertebrates that contributes to the growth of plants and fertility improvement of soil. Remilitine fungicide is commonly used by farmers in agriculture in the Benghazi region, whereas Chromium is one of the main soil pollutants, however, more studies are needed concerning its toxicity in soil organisms. Consequently, chromium was selected to be used in this research. Along with Remilitine fungicide and Chromium as well as Remilitine fungicide separately and in combination the body growth of the earthworm, Eisenia fetida in the laboratory. All worms were adults and fully clitellated. The adult worms were exposed to 70 days of sublethal concentration of Remilitine500ppm and Chromium200 ppm as well as the mixture of Remilitine -Chromium (200+ 500ppm). The worms of control treatment reported significantly greater body weight (F= 5.4, P < 0.05), as compared to that of Remiltine treated worms Furthermore, significant differences in worm were also revealed body weight between the control and chromium treated worms after 70 days (F=10.33, P<0.05). These results also reveal statistically significant differences in body weight between the Remilitine -chromium mixture and the control (F=14.57 P<0.05). From these results, it is concluded that the interaction type of Chromium and Remilitine combined toxicity is antagonistic.