Renewable energy sources experience problems such as deregulation when they are used as stand-alone energy sources. This paper presents an optimal power sharing and power control strategy combining a photovoltaic (PV) array, a fuel cell (FC) stack, an ultra-capacitor (UC) module, and a set of loads. The photovoltaic is the prior energy source while the fuel cell (FC) system is added as a backup source to meet the excess power demand. The ultra-capacitor (UC) is utilized as a buffer storage to compensate the slow dynamic response of the FC during transient and regulate the DC-bus voltage. The power control strategy is designed to work on a two-level arrangement. The top level controls the entire power management, which generates references to low level individual subsystems depending upon solar radiation, temperature, and load conditions. Based on the command signals, each local controller controls the PV, FC, electrolyzer, and UC. The top level also controls the load scheduling during low solar radiation in order to sustain the system operation for 24 h. The performance of the system is tested under real-world record of solar radiation, temperature, and load conditions for Bahria town at Islamabad, Pakistan. The effectiveness of the proposed model in terms of voltage regulation, power transfer, load tracking, and grid stability is verified by Matlab simulation results.
This paper presents a new mobile hybrid system using a photovoltaic array, a wind turbine, an ultracapacitor, and a battery bank for grid-independent applications in the city of Cancun, Mexico. A main controller is proposed to manage these different power sources. This controller permits autonomous operation and control over power generation and loading. This proposal used high power and high energy density storage devices, including short- and long-term storage strategies for energy management. An independent load management subsystem was added, given that the mobile application requires the management of critical loads. This subsystem included an ON/OFF pattern for the connection and disconnection of DC and AC power outlets installed inside and outside the mobile unit. In order to verify system performance, each component of the system was modeled and simulated under realistic operating scenarios with a practical load using MATLAB, Simulink, and SimPowerSystems. The results obtained for this simulation showed that, by means of power balancing, this management scheme coordinated the power flow among the different sources and the load. The manager behavior shows that the difference between the power generated and the power demand was 2.08 kW h/day and 4.01 kW h/day in winter and summer, respectively.
This article presents the development of a low cost network of wireless sensors that use an open source hardware platform, consisting of an ESP8266 and a digital temperature-humidity sensor to measure the parameters in an area determined by the range of the sensor. The general development of the system includes the use of open source software to receive information through the network. Tests of sensor effectiveness were performed at three different points in an air-conditioned area. The first sensor was placed outside the area, the second in the middle and the last one at the exit of the air conditioning. The results obtained allowed to know the behavior of temperature and humidity in the area and the effectiveness of the sensor network to measure the variables, the results of the measurements are presented in detail. Because the system is highly scalable, inexpensive and easy to build compared to other systems, it is a good choice for a wide variety of applications.
In photovoltaic (PV) systems, inverters have an essential role in providing an energy supply to meet the demand with power quality. Inverters inject energy into the grid considering that a renewable source is available; however, during intermittent periods or in the absence of power generation, the inverter remains inactive, which decreases the performance of the PV system. One way to increase the operation of inverters is to operate them as Volt-Amps Reactive (VAR) compensators to generate reactive power in the absence of renewable sources. The paper presents the development of a control scheme that allows the PV system’s inverter to improve the power factor in the electrical system with or without PV power generation. The proposed control is based on using a sliding mode controller (SMC) current control loop and PI-based voltage control loop. The control scheme is developed in MATLAB/SIMULINK, and for real evaluation, a PV prototype is implemented. The control strategy efficiency is confirmed by the obtained results. The control scheme increases the practical utility of PV systems. Additionally, it improves the power factor in all cases during the injection of active power to the grid operating under intermittent conditions and/or in the absence of power generation.
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