Voltage Control in Low-Voltage Grids Using Distributed Photovoltaic Converters and Centralized Devices

This paper studies the application of distributed and centralized solutions for voltage control in low voltage (LV) grids with high photovoltaic (PV) penetration. In traditional LV grids, the coordination of distributed PV converters and a centralized device would require massive investments in new communication and control infrastructures. The alternative of exploiting distributed PV converters for voltage control is discussed, showing that it can help to stabilize the voltage in the grid connection points also without coordination between them and/or with a centralized unit. The goal of this paper is to investigate how the setup of the voltage controllers inside PV inverters affects the operation of these controllers taking into account the limits for reactive power injection. In addition, the interaction of distributed PV converters with centralized devices (static var compensators and on load tap changers) is analyzed to assess whether additional benefits may come in these cases

Quality Check during Manufacturing of Custom Photovoltaic Modules with Back-Contact Cells

The Electroluminescence (EL) analysis and the current-voltage (I-V) curves determination of PhotoVoltaic (PV) generators are the most used diagnosis methods to check the presence of defects. In the present work, these tests are applied to Interdigitated Back Contact (IBC) PV modules with customizable shape after their manufacturing. A defect is detected in a large number of modules, suggesting an issue related to the semi-automatic manufacturing procedure. Therefore, a detailed analysis is carried out to localize the cause of the defect and a preventive action is proposed in order to reduce the occurrence frequency of the defect during manufacturing

Modeling and experimental determination of the circuit parameters of thin film PV modules/arrays

The Scientific Bulletin of Electrical Engineering Faculty, Valahia University of Targoviste, year 10, no. 3 (14), pp. 132-139, 2010, Bibliotheca Publishing House, Targoviste, Romania, ISSN 1843-618

PV system integration in buildings: An energy and economic case study

PV systems, due to their economies of scale, are nowadays increasingly adopted. The direct consequence of these economies is the cost reduction of the commercial PV technologies (in particular, the crystalline silicon one). Thus, the goal of this paper is to analyze and assess the energy and economic benefits of a PV system integration onto a public library building. The simulations of PV and load power profiles are carried out in this study for different configurations of the PV generator with the goal of minimizing the worsening effect of shading caused by obstacles near the library building

Short-Term Load Forecasting Using Convolutional Neural Networks in COVID-19 Context: The Romanian Case Study

Short-term load forecasting (STLF) is fundamental for the proper operation of power systems, as it finds its use in various basic processes. Therefore, advanced calculation techniques are needed to obtain accurate results of the consumption prediction, taking into account the numerous exogenous factors that influence the results’ precision. The purpose of this study is to integrate, additionally to the conventional factors (weather, holidays, etc.), the current aspects regarding the global COVID-19 pandemic in solving the STLF problem, using a convolutional neural network (CNN)-based model. To evaluate and validate the impact of the new variables considered in the model, the simulations are conducted using publicly available data from the Romanian power system. A comparison study is further carried out to assess the performance of the proposed model, using the multiple linear regression method and load forecasting results provided by the Romanian Transmission System Operator (TSO). In this regard, the Mean Squared Error (MSE), the Mean Absolute Error (MAE), the Mean Absolute Percentage Error (MAPE), and the Root Mean Square Error (RMSE) are used as evaluation indexes. The proposed methodology shows great potential, as the results reveal better error values compared to the TSO results, despite the limited historical data

Modeling and experimental determination of the circuit parameters of thin film PV modules/arrays

The Scientific Bulletin of Electrical Engineering Faculty, Valahia University of Targoviste, year 10, no. 3 (14), pp. 132-139, 2010, Bibliotheca Publishing House, Targoviste, Romania, ISSN 1843-6188

DC MicroGrids

International audienceThis chapter introduces concepts of DC MicroGrids exposing their elements, features, modeling, control, and applications. Renewable energy sources, energy storage systems, and loads are the basics components of a DC MicroGrid. These components can be better integrated thanks to their DC feature, resulting in simpler power converter topologies, as well as the control strategy required for this application. A DC MicroGrid is developed as a realistic average model where the dynamics of the system are expressed in differential equations, including the nonlinearities of the model. A nonlinear distributed control strategy is developed for the DC MicroGrid, assuring the stability of the DC bus to guarantee the proper operation of each component of the MicroGrid. The energy storage systems are separated according to their timescale operation, where a faster one (supercapacitor) controls voltage variations on the DC bus, and a slower one (battery) provides the power flow balance. The comparison with classical linear controllers is carried out to highlight the better performance of the nonlinear approach