عامر عبد المهدي جبار جليحاوي

Abstract. In this paper, the PID controller parameters of a DC-DC buck converter based on error criteria extracted by means of an applied genetic algorithm (GA)are studied. The GA-PID is designed with optimal parameters by minimising integral errors, and the application of these optimal parameters reduces transient response by minimising overshoot, rise time, peak time, and steady state time during step response. The simulation testing was done in MATLAB, and the performance of the proposed GA-PID method was investigated by the simulation of two different plants. The transfer function of the third order system was initially used as a primary simulation for the proposed method, while DC-DC buck converters were used in the second simulation. The results obtained demonstrate the feasibility of employing genetic algorithms to generate optimal parameters for PID controllers for the further development of DC-DC buck converters.

A novel low frequency magneto-electric energy harvester was developed for application in microelectronic devices. The energy harvester was fabricated by screen printing polyvinylidene fluoride (PVDF) ink, as a piezoelectric layer, on flexible and magnetic Metglas® substrate. Silver (Ag) ink, as top electrode layer, was then deposited on the printed PVDF layer using screen printed technique. The performance of the printed device was investigated by measuring the DC output voltage and maximum power delivered at varying load resistances for a frequency range of 20 Hz to 100 Hz, in steps of 20 Hz. The results demonstrated that the maximum power generated was 8.41 μW at a load resistance of 100 kΩ and frequency of 100 Hz. This relates to a power density of 639.6 μW/cm3 for the fabricated magneto-electric energy harvester.

A d3i mode piezoelectric based vibration energy harvester (PVEH) has been successfully fabricated using screen printing technique for wireless micro sensor network applications. Polyvinylidene fluoride (PVDF), as a piezoelectric layer, was screen printed onto a glass substrate. The cured screen printed PVDF film was peeled off from the glass substrate and polarized by applying 10 kV across its layer. The polarized PVDF layer was sandwiched between two Metglas conductive electrodes, to form a d31 mode unimorph cantilever beam structure. The fabricated PVEH device was mechanically excited at its first resonance frequency (54 Hz) using base shaking experiments. The experimental results demonstrated that the developed energy harvester generated a maximum DC voltage of 1.35 V across a 10 Mfi load and a peak power output of 0.28 μW was delivered to a 1 MΩ resistive load at 0.53 V DC for a sinusoidal vibration of 15 g. The corresponding power density of the device was calculated to be 11.67 μW/cm3.

The optimization of a suitable controlling method is a priority in running any DC/DC boost converter effectively. However, a problem may arise as the occurring oscillations in the microgrid caused by the incremental negative resistance of the Constant Power Poad (CPL) variation may lead to system instability. In order to tackle this intrinsic problem, three proposed Sliding Mode Control (SMC) methods were simulated and examined against multiple variations of CPL in MatLab/Simulink. Integral Sliding Mode Control (ISMC) and Two-variable Sliding Mode Control (TSMC) methods showed a better system performance than the Low Pass Filter SMC (LPFSMC) in terms of stability of output voltage in both steady state and transient conditions. The output voltages of ISMC and TSMC had a margin of error of approximately 1 V in the steady-state response and a minor overshoot of less than 1% in the transient response. The steady-state output voltage when using LPFSMC showed approximately 3 V of error and the transient state had a noticeable overshoot near 3%. However, all three controlling methods had a similar efficiency of around 98%. The outstanding robustness of ISMC exhibited the highest voltage stability with the lowest chattering in both steady state and transient responses through the compensation of adequate current to satisfy the CPL requirement. Keywords: DC microgrid, sliding mode controller, boost converter, constant power load, voltage stability

This article offers a study about the Maximum Power Point Tracking (MPPT) of photovoltaic (PV) System and Hybrid Energy Storage Systems (HESSs) management to enhance environmental sustainability by achieving the following aims: keep the voltage stability of DC microgrid (MG) at a standard value, provide maximum amounts of power to the loads and long-term stability. Research into improving renewable energy for the sustainable development goals due to the problem of increasing climate change and energy security, is on high demand. The largest contribution focus on integrating PV system to operate in MPPT to increase the efficiency of solar cells, improved power electronic converter and use efficient tracking algorithm. This study comprises the design of MPPT for DC/DC boost converter and using perturb and observe (P&O) algorithm. The major energy source for the proposed system is PV panels. The control approach of Supertwist Slide Mode Control (STSMC) was used for improving module efficiency of PV system to operate at optimal state under a variety of irradiation conditions. It has been observed that the modified optimization algorithm searches for optimum proportional Integral (PI) controller to keep the voltage at the reference value. The performance of the control process scheme was designed and examined using MATLAB/SIMULINK program. In optimal renewable energy management system strategy, a protection modification is to prevent battery overcharge by limiting its degradation and improving system stability and reliability.