A simple circuit to improve the power yield of PV array during partial shading

In a typical photovoltaic (PV) power system, when part of the PV module is shaded, the bypass diode is activated to protect the module from hot-spot damages. As a result, the output power is reduced significantly because the power generated from the shaded module is totally unusable. In this paper, a simple circuit is proposed to increase the power yield of PV system under partial shading condition. The idea is to recover the power generated by the shaded module and then process it using power electronics circuit to become part of the output power. Consequently, the inclusion of the circuit enables the system to deliver more power compared to the bypass diode method. The concept is evaluated using Matlab-Simulink simulation and proven using an experimental test rig. The performance of the proposed circuit is compared with (1) PV system with bypass diode and (2) micro-inverter. The results show marked improvement in the efficiency, especially under heavy partial shading condition

AC Voltage Regulation of a Bidirectional High-Frequency Link Converter Using a Deadbeat Controller

This paper presents a digital controller for ac voltage regulation of a bidirectional high-frequency link (BHFL) inverter using deadbeat control. The proposed controller consists of inner current loop, outer voltage loop and a feed-forward controller, which imposes a gain scheduling effect according to the reference signal to compensate the steady-state error of the system. The main property of the proposed controller is that the current- and the voltage-loop controllers have the same structure, and use the same sampling period. This simplifies the design and implementation processes. To improve the overall performance of the system, additional disturbance decoupling networks are employed. This takes into account the model discretization effect. Therefore, accurate disturbance decoupling can be achieved, and the system robustness towards load variations is increased. To avoid transformer saturation due to low frequency voltage envelopes, an equalized pulse width modulation (PWM) technique has been introduced. The proposed controller has been realized using the DS1104 digital signal processor (DSP) from dSPACE. Its performances have been tested on a one kVA prototype inverter. Experimental results showed that the proposed controller has very fast dynamic and good steady-state responses even under highly nonlinear load

A retrofit circuit to increase output power of PV system during partial shading condition

In a typical photovoltaic (PV) distributed generation system, when part of the PV module is shaded, the bypass diode (that is connected in parallel to it) is used to protect the module from hot-spot damages. However, by employing this diode, the output power is reduced significantly because the power generated from the shaded module is totally unusable. Furthermore, when the current flows through the bypass diode, conduction losses occur which further degrade the system efficiency. In this paper, a simple retrofit circuit is proposed to increase the output power of PV system under partial shading condition. The idea is to utilize the current generated by the shaded module, detour it to a power electronics circuit and then process it to become part of the output power. Consequently, the inclusion of the retrofit circuit enables to system to deliver more power compared to the bypass diode method. Simulation results show marked improvement in the efficiency, especially under heavy partial shading condition

An Improved `DC-DC Type' High Frequency Transformer-Link Inverter by Employing Regenerative Snubber Circuit

This work proposes a bidirectional high frequency (HF) link inverter using center-tapped high frequency transformer. The main advantage of this topology is the reduced size of the converter. However the utilization of the high frequency transformer results in the occurrence of high voltage spike at its secondary. To solve this problem, we incorporate a regenerative snubber to clamp the spike and subsequently feed the energy back to the power circuit. The inverter also utilizes less number of switches, which results in lower conduction and switching losses. This paper describes some of the important aspects of the snubber design. It is verified with a 1 kW inverter prototyp

Comparative analysis of the model-free tuning techniques for integral state feedback controller of a liquid slosh suppression system

This paper presents a comparative study of the model-free controller tuning for a liquid slosh suppression system. Data-driven Pole Placement (DPP) and Fictitious-Reference-Iterative-Tuning with Particle Swarm Optimization (FRIT-PSO) are the two algorithms proposed as the tuning methods for the selected controller structure. These techniques are desirable to obtain the optimal parameters gain of the state feedback controller with the integral term by utilizing only the recorded input-and-output data generated from a one-shot experiment. The system’s performance analysis of the controlled system is carried out using MATLAB Simulink. The assessment proves that the model-free control approaches exhibit a good response of the cart in terms of the trajectory tracking of the cart’s motion while maintaining the liquid slosh motion at the minimum level

Frame Optimization using Neural Network

The development of Neural-network (NN) technology stemmed from the desire to create an artificial system that could perform “intelligent” tasks similar to those performed by the human brain. In this paper the performance of NN to the structural optimization concept of frame structure is presented. The optimum set of frame designs is obtained using Finite Element (FE) software where stress and displacement constraints has been chosen as the optimum criteria. The optimized data then used to train the NN through Back Propagation Neural-network technique (BPNN) to identify the capability of this strategy to predict the exact data. Three case studies were performed with different complexity of structural configuration. Result indicates the Neural-network capable of predicting the exact solution with proper training but this ability depends on the complexity of the frame structural optimization itself

State feedback controller tuning for liquid slosh suppression system utilizing LQR-LMI approach

This paper presents a tuning constraint optimization approach in state feedback controller for liquid slosh suppression system. A suboptimal LQR method is employed to obtain the optimal gain parameters in minimizing the selected cost function. Due to complexity of the nonlinear slosh system, a partial linearization method was first performed to obtain its linear state space representation. Due to the presence of the large steady-state error caused by the implementation of only the state feedback gains, an additional integral term has also been introduced to mitigate its effects. A comparative assessment on the system performance is investigated between regular LQR and LQR-LMI control algorithms. The presented results indicated that the LQR-LMI exhibited better transient response performance as compared to the regular LQR for the case of moving the cart to its intended final position while ensuring the slosh motion is suppressed to a minimum angle

Hardware Approach To Mitigate The Effects Of Module Mismatch In A Grid-Connected Photovoltaic System: A Review

This study reviews the hardware approach to mitigate the effects of module mismatch in a grid-connected photovoltaic (PV) system. Unlike software solutions, i.e. the maximum power tracking algorithm, hardware techniques are well suited to enhance energy yield because of their inherent ability to extract energy from the mismatched module. Despite the extra cost of the additional circuitry, hardware techniques have recently gained popularity because of their long-term financial benefits. Notwithstanding the growing interest in this topic, review papers that provide updates on the technological developments of the three main hardware solutions, namely micro inverter,DC power optimizer, and energy recovery circuits, are lacking. This is in contrast to software solutions, which have had a considerable number of reputable reviews. Thus, a comprehensive review paper is appropriate at this juncture to provide up-to-date information on the latest topologies, highlight their merits/drawbacks, and evaluate their comparative performance

Development of a Pico-Hydro Generating System with SES-BMS for Domestic Use

Non-renewable resources have decreased significantly over the past decade, whereas, the current renewable energy system is expensive and more focused on large-scale use. The goal of this project was to design a user-friendly pico-hydro system with a Smart Energy Storage Battery Management System (SES-BMS) to utilize the potential of domestic water flow while saving energy consumption and daily costs. The overall system is a combination of the standard pipeline, a pico-turbine, the SES-BMS and a simple light source. The flow of water is utilized by converting kinetic energy into electrical energy. The design was performed by using the Engineering Design Process (EDP) with coding via Arduino microcontroller. The main outcome of this project was a proof of concept that showed the potential for domestic use of the pico-hydro system combined with the SES-BMS system. Compared to the previous mini-hydro design, the new system showed an increase in performance during the average flow rate in the domestic pipeline, generating an improved value of 68 mW of power during the flow rate of 0.075 x 10-3 m3/s. An optimal charging time of 10 hours is recommended to accommodate the 3.5-hour use of a 12W LED lamp, to maintain the stability and reliability of the system, especially the battery pack

Development of a Pico-Hydro Generating System with SES-BMS for Domestic Use

Non-renewable resources have decreased significantly over the past decade, whereas, the current renewable energy system is expensive and more focused on large-scale use. The goal of this project was to design a user-friendly pico-hydro system with a Smart Energy Storage Battery Management System (SES-BMS) to utilize the potential of domestic water flow while saving energy consumption and daily costs. The overall system is a combination of the standard pipeline, a pico-turbine, the SES-BMS and a simple light source. The flow of water is utilized by converting kinetic energy into electrical energy. The design was performed by using the Engineering Design Process (EDP) with coding via Arduino microcontroller. The main outcome of this project was a proof of concept that showed the potential for domestic use of the pico-hydro system combined with the SES-BMS system. Compared to the previous mini-hydro design, the new system showed an increase in performance during the average flow rate in the domestic pipeline, generating an improved value of 68 mW of power during the flow rate of 0.075 x 10-3 m3/s. An optimal charging time of 10 hours is recommended to accommodate the 3.5-hour use of a 12W LED lamp, to maintain the stability and reliability of the system, especially the battery pack