DSP-based flexible digital hysteresis in switched capacitor active power filter

This paper proposes implementation of digital signal processor (DSP) to perform flexible-band digital hysteresis current control in a switched capacitor active power filter (SCAPF). By integrating hysteresis current control with digital-based neural network harmonic detection, the proposed SCAPF forces the supply current to be sinusoidal, to have low current harmonics, and to be in phase with the line voltage. Simulation on MATLAB Simulink verified the controller's algorithm design, and a purpose-built laboratory SCAPF system tested its feasibility

Experimental investigation of on-site degradation of crystalline silicon PV modules under Malaysian climatic condition

Photovoltaic (PV) power plant capacity is growing very fast in Malaysia. The operating capacity of a PV plant digresses from the installed capacity after several years of operation. The degradation rate of different poly and mono crystalline silicon PV modules due to real field aging at various time spans has been detected by EL imaging, maximum power measurement and dark I-V analysis. The obtained degradation values of PV modules are 1.78, 7.06, 13.92, 17.04 and 17.42% due to ageing at a period of 8 months, 16 months, 4 years, 9 years and 11 years, respectively. The reason behind this degradation is attributed to the reduction of shunt resistance which declines gradually as result of aging. The degradation rate of a PV module has been estimated as 18.61% after 21 years of aging. Temperature coefficient of maximum power of PV module also degrades due to aging. And the rate of temperature coefficient of maximum power degradation decreases with the increase of aging period

Fuzzy Logic Control Approach of a Maximum Power Point Employing SEPIC Converter for Standalone Photovoltaic System

AbstractThis paper presents a new fuzzy logic controller as a maximum power point tracker employing single-ended primary-inductor (SEPIC) converter. The new controller improves perturb and observe search method with rules to fuzzify and eliminate its drawbacks. An accurate and fast converging to maximum power point is offered by fuzzy logic tracker during both steady-state and varying weather conditions compared to conventional maximum power point tracking methods. The performance of the proposed maximum power point tracker is demonstrated in both simulation and experiment at different operating conditions

A Simple THD Minimization Technique for Transistor-Clamped H-Bridge-Based Cascaded Multilevel Inverter

This paper presents a simple modulation technique that minimizes the output voltage total harmonic distortion (THD) without eliminating the lowest order harmonics. It uses the voltage-angle equal concept of sinusoidal reference waveform to generate the step output voltage of a single-phase transistor-clamped H-bridge (TCHB)-based cascaded multilevel inverter. The real implementation of the modulation technique for a various range of modulation indices is built using an Altera field-programmable gate array (FPGA). It is found that the proposed modulation method resulted in a dramatic decrease in the inverter’s output voltage THD when increasing the number of output steps up to thirteen levels

Impact of fill factor on input current ripple of photovoltaic system

This paper discusses the impact of fill factor on the input current ripple of the photovoltaic module and the loss effect on power extracted. Photovoltaic module's P-V curve produces exponential curve. The curvature of this curve indicates the fill factor of the particular cell; hence, by increasing the fill factor, the available extracted power increases. Yet, this paper states that losses due to photovoltaic current increases by increasing the fill factor

Three-phase switched capacitor active power filter with modified artificial neural network and flexible-band hysteresis.

This paper presents design and development of a three-phase switched capacitor active power filter (APF) to reduce line-current harmonics and operate in-phase with line voltage. Its control design combines a modified artificial neural network (ANN) harmonic detection technique and flexible-band hysteresis current control. The modified ANN with a suitable learning rate produces good and fast harmonic reference current for use in the switching algorithm, which performs flexible-band through embedded with band and without band hysteresis current control. MATLAB Simulink software verified the proposed APF's topology and controller. A laboratory-built three-phase switched capacitor APF tested its feasibility. Simulation and experimental results verified its performance. It compensated harmonic current well, and the source current waveform became almost sinusoidal with near unity power factor. The results show that the three-phase switched capacitor APF with the modified ANN and the digital flexible-band hysteresis current algorithms could reduce THD and could increase power factor of the system

Current limiter strategy of grid-connected pv system for LVRT Enhancement

A low-voltage ride-through (LVRT) is an ancillary service provided to a power grid to stabilize the grid voltage under weak grid conditions. Under these circumstances, a short-term disturbance is allowed to be ride-through to prevent unnecessary nuisance tripping during weak grid conditions. The main objective of this paper is to propose an active power curtailment strategy for a 1.038 MW grid-connected photovoltaic (PV) system to enhance the LVRT capability. A simple current limiter was applied to regulate the excessive DC-link voltage while the reactive power was controlled by a PI-tuning controller to maintain the voltage profile. Using MATLAB/Simulink environment, the dynamic behaviors of the proposed system were tested under 70% voltage sag and it was found that the proposed strategy is successful in curtailing the active power during low-voltage conditions and the excessive DC-link voltage can be controlled. Meanwhile, the whole system can maintain its operation without inverter disconnection and the voltage profile was improved even under weak grid conditions