The development of photovoltaic (PV) technology is now a reality. The inclusion of lithium-ion batteries in grid-connected PV systems is growing, and the sharp drop in prices for these batteries will enable their use in applications such as PV water pumping schemes (PVWPS). A technical solution for the monitoring and tracking of PV systems is shown in this work, and a novel quasi-real-time monitoring system for a PVWPS with a Li-ion battery is proposed in which open-source Internet of Things (IoT) tools are used. The purpose of the monitoring system is to provide a useful tool for the operation, management, and development of these facilities. The experimental facility used to test the monitoring system includes a 2.4 kW_pk photovoltaic field, a 3.6 kVA hybrid inverter, a 3.3 kWh/3 kW lithium-ion battery, a 2.2 kVA variable speed driver, and a 1.5 kW submersible pump. To address this study, data acquisition is performed using commercial hardware solutions that communicate using a Modbus-RTU protocol over an RS485 bus and open software. A Raspberry Pi is used in the data gateway stage, including a PM2 free open-source process manager to increase the robustness and reliability of the monitoring system. Data storage is performed in a server using InfluxDB for open-source database storage and Grafana as open-source data visualization software. Data processing is complemented with a configurable data exporter program that enables users to select and copy the data stored in InfluxDB. Excel or .csv files can be created that include the desired variables with a defined time interval and with the desired data granularity. Finally, the initial results of the monitoring system are presented, and the possible uses of the acquired data and potential users of the system are identified and described.

This paper presents the simulated and experimental results of an improved shunt active power compensator (SAPC). The proposed power compensator achieves IEEE Standard 1459 compliance by using moving-window discrete Fourier transform (DFT) calculations to obtain reference currents, and a time-efficient current regulator. The current regulator is based on the analysis of the per-phase electrical model of the (APC). The main feature of the proposed current regulator is the good compromise between current control behavior and time execution efficiency. This compromise results in a low computational cost current regulator with suitable control features, which allows for the implementation of a high-frequency acquisition current control loop, including an extensive computation method based on the use of moving-window DFTs to obtain the proper reference currents with every new sample. The reference current calculations follow the power decomposition proposed by IEEE Standard 1459 for maximum efficiency in supply currents. Simulated and experimental results demonstrate that the proposed SAPC operates correctly under unbalanced and nonsinusoidal conditions. A timing performance comparison is done between the proposed current control and the dq0 technique.

This work presents the conversion of a photovoltaic water pumping system (PVWPS) to its corresponding battery-based solution, while maintaining the components of the PVWPS facility and adding the power converter needed to manage the operation of a lithium-ion battery. A complete analysis of the direct PVWPS is performed based on the values obtained by the monitoring system developed for the installation. The efficiencies and performance ratios of the various elements of the facility are calculated, as well as other relevant factors (such as irradiance thresholds). The dependence of some variables on the solar resource is analyzed to model the system. A similar study is carried out in the battery-based solution and a comparative analysis of the two modes of operation is then performed to find which aspects could be improved in the battery-based solution to increase the pumping time and total daily pumped volume. The results presented demonstrate the benefits of including a battery (reduction in start/stop cycles and improved performance on cloudy days). Aspects that can be improved to make the battery-based solution more efficient and achieve better results are suggested.

The second-order generalized integrator (SOGI) filter and delayed signal cancellation (DSC) structures have been used separately in order to improve the synchronization systems response in adverse grid conditions. Taking into account its characteristics, this paper proposes a new structure based on a combination of SOGI filter, DSC method, and a software phase-locked loop (S). The enhanced synchronization structure is used to estimate the fundamental positive-sequence component of grid voltages (v_s1⁺) in distorted and asymmetric three-phase systems. DSC and SOGI working in the stationary αβ frame are used to obtain the v_s1⁺ component, while S in a synchronous reference frame (SRF) or the d-q frame is used to obtain v_s1⁺ pulsation and phase. The cutting frequency of the SOGI filter is selected by taking into account the capability of DSC to eliminate determinate order harmonic components. The bandwidth of S is adjusted to achieve a good relation between dynamic response and filtering capability. The SOGI filter has an adaptive structure to modify its cutting frequency when a variation in the fundamental frequency of grid voltages occurs. The performance of the proposed structure is verified through simulations and experimental cases, using a grid set of voltages that include all nonefficient voltage components (distortion, asymmetries, and negative-sequence components).

This paper proposes a new on-site technique for the experimental characterization of small wind systems by emulating the behavior of a wind tunnel facility. Due to the high cost and complexity of these facilities, many manufacturers of small wind systems do not have a well knowledge of the characteristic $\lambda$ - $C_p$ curve of their turbines. Therefore, power electronics converters connected to the wind generator are usually programmed with speed/power control curves that do not optimize the power generation. The characteristic $\lambda$ - $C_p$ curves obtained through the proposed method will help manufacturers to obtain optimized speed/power control curves. In addition, a low cost small wind emulator has been designed. Programmed with the experimental $\lambda$ - $C_p$ curve, it can validate, improve, and develop new control algorithms to maximize the energy generation. The emulator is completed with a new graphic user interface that monitors in real time both the value of the $\lambda$ - $C_p$ coordinate and the operating point on the 3D working surface generated with the characteristic $\lambda$ - $C_p$ curve obtained from the real small wind system. The proposed method has been applied to a small wind turbine commercial model. The experimental results demonstrate that the point of operation obtained with the emulator is always located on the 3D surface, at the same coordinates (rotor speed/wind speed/power) as the ones obtained experimentally, validating the designed emulator.