Gigantic population and comprehensive electrical energy consumption have made power crisis one of the gravest national problems in the developing countries like Nigeria. Excessive demand of power is always difficult to meet and as a result national economy is being hampered severely due to this deregulation of electricity. Alternative power sources that can deliver output currents in absence of grid supply are now automatic choices in home grid-connected system. In urban areas, IPS (Instant Power Supply) system is being used massively to cope up with load shedding.
Increasing interest and investment in renewable energy give rise to rapid ...view middle of the document...
In this manner, the peak power tracker continuously seeks the peak power condition.
However, MPP is tracked by using DC-DC converters (Jung, 2009). Much attention has been given to the single endedprimary inductor converter (SEPIC) topology recently because output voltage may be either higher or lower than input voltage .The output is also not inverted as is the case in a fly back topology. The input and output voltages are DC isolated by a coupling capacitor and the converter works with constant frequency PWM.
Similarly, Inverters are static power converters that produce an ac output waveform from a dc power supply. The dc power from SEPIC is fed to inverter to get ac output power (Chenvidhya et al, 2008). A Bi-Directional DC-DC Converter (BDC) is connected between the Sepic Converter and Inverter. BDC is used to store the dynamic energy in battery and supply to load when there is overcast sky or at night (Lin et al, 2008). For sinusoidal ac outputs, the magnitude and frequency should be controllable. This is done by comparing a sinusoidal wave of the same frequency as inverter output against triangular carrier frequency wave. This technique called sinusoidal pulse width modulation (SPWM) mainly used because of its simplicity and ease of implementation. The output voltage magnitude is controlled by closed loop control system using PI controller (Balathandayuthapani et al, 2010).
As the capacity of PV system growing significantly, the impact of PV modules on power grid can’t be ignored. They can cause problems on the grid like flicker, increase of harmonics, and aggravated stability of the power system. To both increase the capacity of PV arrays and maintain power quality, it’s necessary to comply with the technique requirements of the PV system, such as fault-ride-through capability and harmonic current regulation. Especially when a large scale PV module is connected to the grid, the effects on the grid may be quite severe. Therefore, the system operation and system stability under fault conditions should be examined when PV modules are interface with power grid.
A micro PV system structure in which two PV modules connected in series is considered and it provides an output power of nearly 160 Watts. To address the micro PV system structure, this project work proposes a novel MPPT algorithm, which is based on the improved research on the characteristics of the PV array to track the global MPP even under non-uniform insulation. Battery charging and discharging is done using BDC (Bidirectional converter). BDC is operated in three modes namely; Buck Boost and Bidirectional. The algorithm was verified with MATLAB/SIMULINK that it can track the real MPP very fast when the temperature changes. The closed loop operation of proposed system is verified with MATLAB simulations including Load and source disturbances.
Simulation of modern electrical systems using power electronics has always been a challenge because of the nonlinear behavior of power...