Reliability Prediction of Smart Maximum Power Point Converter for PV Applications

The photovoltaic generation distribution supports new energetic scenario development (Net Zero Energy Cluster and DC microgrids). In this context, smart maximum power point (SMPPT) converter represents innovative systems that are able to monitor operating conditions, communicate energetic production data and signal a fault condition. The Smart Maximum Power Point role becomes crucial, and critical aspects such as efficiency and reliability have to be taken into account from the beginning of the design. In this chapter, the idea is to review different reliability prediction models for electronic components focusing on the military ones with the analysis of a case study related to a Smart Maximum Power Point converter in photovoltaic applications

A joint approach for strategic bidding of a microgrid in energy and spinning reserve markets

n the electricity market, short-term operation is organized in day-ahead and real-time stages. The two stages that are performed in different time intervals have reciprocal effects on each other. The paper shows the strategy of a microgrid that participates to both day-ahead energy and spinning reserve market. It is supposed that microgrid is managed by a prosumer, a decision maker who manages distributed energy sources, storage units, Information and Communication Technologies (ICT) elements, and loads involved in the grid. The strategy is formulated considering that all decisions about the amount of power to sell in both markets and the price links to the offer, must be taken contextually and at the same time, that is through a joint approach. In order to develop an optimal bidding strategy for energy markets, prosumer implements a nonlinear mixed integer optimization model: in this way, by aggregating and coordinating various distributed energy sources, including renewable energy sources, micro-turbines–electricity power plants, combined heat and power plants, heat production plants (boilers), and energy storage systems, prosumer is able to optimally allocate the capacities for energy and spinning reserve market and maximize its revenues from different markets. Moreover, it is considered that both generators and loads can take part in the reserve market. The demand participation happens through both shiftable and curtailable loads. Case studies based on microgrid with various distributed energy sources demonstrate the market behavior of the prosumer using the proposed bidding model

A radial basis function neural network based approach for the electrical characteristics estimation of a photovoltaic module

The design process of photovoltaic (PV) modules can be greatly enhanced by using advanced and accurate models in order to predict accurately their electrical output behavior. The main aim of this paper is to investigate the application of an advanced neural network based model of a module to improve the accuracy of the predicted output I--V and P--V curves and to keep in account the change of all the parameters at different operating conditions. Radial basis function neural networks (RBFNN) are here utilized to predict the output characteristic of a commercial PV module, by reading only the data of solar irradiation and temperature. A lot of available experimental data were used for the training of the RBFNN, and a backpropagation algorithm was employed. Simulation and experimental validation is reported

a new approach for the dimensioning of an air conditioning system with cold thermal energy storage

Abstract In this work, a new approach for the design of air conditioning systems with cold thermal energy storage is described and tested, considering the case study represented by a vapor-compression chiller, coupled with a chilled water storage system, producing cooling for a small multi-apartment building situated in Italy. In the present approach, at the aim of limiting shut-downs and start-ups of the chiller, which involve inefficiencies during transients, and can lead to a drastic reduction of the equipment lifetime, the nominal power of the chiller, and the amount of cooling to be stored are first estimated in a pre-design phase. Successively, the outputs of the pre-design are used to fix the size of the cold storage tank, and to set up the numerical simulation of the cold thermal energy storage system. Finally, the results of the numerical simulation of the cold storage system are used to evaluate the effective size of the chiller. Both the pre-design and the numerical simulations of the cold storage systems have been done by means of home-made numerical tool realized with Simulink. In the paper, the specifications relative to the operational strategy are explored, and the analytical models used for the numerical simulation of the cold storage system relative to the Italian case study are reported in detail. Finally, the results of the pre-design, and of the cold storage system simulations relative to the case study are presented and discussed. The results relative to the Italian case study demonstrates the effectiveness of the present approach in limiting the number of shut-downs and start-ups of the chiller. The present approach can represent a useful tool for the economic optimization of the design of air conditioning systems

analysis of a biomass fired cchp system considering different design configurations

Abstract This work aims to present the results of an energetic and economic analysis of a biomass fueled CCHP system operating according to different design configurations. The investigated system consists of a biomass-fueled cogeneration unit, an absorption chiller, a thermal energy storage system and a cold one, providing electricity, heat and cooling to an Italian cluster of buildings. For each simulated configuration, the feasible investment cost of the CHP unit is evaluated considering the economic savings obtained with respect to separate generation of electricity, heat and cooling. The best configuration from the economic point of view is indicated, and the incidence of the variation of the absorption chiller and storage systems sizes on the feasible investment cost of the CHP unit is evaluated and discussed as well. Results indicate that the most influencing parameter is represented by the absorption chiller power

experimental validation of a tool for the numerical simulation of a commercial hot water storage tank

Abstract This work focuses on the experimental validation of a numerical tool realized to simulate a commercial hot water storage tank. The tool implements unsteady 1D models to simulate the temporal evolution of the temperature field inside the hot water storage tank, and the one relative to the heat transfer fluid flowing through the immersed coil heat exchanger. It has been implemented by means of the Simulink tool of Matlab. The first part of the paper is dedicated to the description of the indoor experimental facility used to realize the experimental test. Successively, the analytical models, and the numerical schemes and algorithms used to perform the numerical simulations are described. Finally, the results of the experimental validation of the tool, accomplished by comparing the experimental temperature profiles inside the tank, and the measured temperatures at the coil heat exchanger exit section over the entire experimental test duration, with the numerical results obtained from simulations performed using different correlations for the evaluation of the heat transfer rate between the tank water and the heat transfer fluid through the coil, are reported and discussed

Transient Analysis of a Solar Domestic Hot Water System Using Two Different Solvers

Abstract In the present work the unsteady numerical simulation of a solar domestic hot water (DHW) system composed of two flat plate collectors, a water tank for heat storage, and a coil heat exchanger is addressed. The simulations have been performed using two different solvers, namely a home-made code written in Matlab, and TRNSYS 17. In the first part of the paper, the analytical models used in the Matlab code, and the TRNSYS case are reported in detail. Successively, the results of the simulations realized by means of the two solvers are presented and compared

measurement and comparison of reliability performance of photovoltaic power optimizers for energy production

Abstract Photovoltaic (PV) power optimizers are introduced in PV systems to improve their energetic productivity in presence of mismatching phenomena and not uniform operating conditions. Commercially available converters are characterized by different DC-DC topologies. A promising one is the boost topology with its different versions. It is characterized by its circuital simplicity, few devices and high efficiency values - necessary features for a Distributed Maximum Power Point Tracking (DMPPT) converter. PV power optimizer designs represent a challenging task since they operate in continuously changing operating conditions which strongly influence electronic component properties and thus the performance of complete converters. An aspect to carefully analyze in such applications is the thermal factor. In this paper, a necessity to have a suitable temperature monitoring system to avoid dangerous conditions is underlined In addition, another important requirement for a PV power optimizer is its reliability, since it can suggest a useful information on its diagnostic aspects, maintenance and investments. In fact, a reliable device requires less maintenance services, also improving the economic aspect. The evaluation of the electronic system reliability can be carried out using different reliability prediction models. In this paper, reliability indices, such as the Mean Time Between Failure (MTBF) or the Failure Rate of a Diode Rectification (DR) boost, are calculated using the evaluation of the Military Handbook 217F and Siemens SN29500 prediction models. With the reliability prediction results it has been possible to identify the most critical components of a DMPPT converter and a measurement setup has been developed in order to monitor the component stress level on the temperature, power, voltage, current, and energy in the DMPPT design phase avoiding the occurrence of a failure that might decrease the service life of the equipment

Fast Hybrid MPPT Technique for Photovoltaic Applications: Numerical and Experimental Validation

In PV applications, under mismatching conditions, it is necessary to adopt a maximum power point tracking (MPPT) technique which is able to regulate not only the voltages of the PV modules of the array but also the DC input voltage of the inverter. Such a technique can be considered a hybrid MPPT (HMPPT) technique since it is neither only distributed on the PV modules of the PV array or only centralized at the input of the inverter. In this paper a new HMPPT technique is presented and discussed. Its main advantages are the high MPPT efficiency and the high speed of tracking which are obtained by means of a fast estimate of the optimal values of PV modules voltages and of the input inverter voltage. The new HMPPT technique is compared with simple HMPPT techniques based on the scan of the power versus voltage inverter input characteristic. The theoretical analysis and the results of numerical simulations are widely discussed. Moreover, a laboratory test system, equipped with PV emulators, has been realized and used in order to experimentally validate the proposed technique

Management of renewable-based multi-energy microgrids in the presence of electric vehicles

This study proposes a stochastic optimisation programming for scheduling a microgrid (MG) considering multiple energy devices and the uncertain nature of renewable energy resources and parking lot‐based electric vehicles (EVs). Both thermal and electrical features of the multi‐energy system are modelled by considering combined heat and power generation, thermal energy storage, and auxiliary boilers. Also, price‐based and incentive‐based demand response (DR) programs are modelled in the proposed multi‐energy MG to manage a commercial complex including hospital, supermarket, strip mall, hotel and offices. Moreover, a linearised AC power flow is utilised to model the distribution system, including EVs. The feasibility of the proposed model is studied on a system based on real data of a commercial complex, and the integration of DR and EVs with multiple energy devices in an MG is investigated. The numerical studies show the high impact of EVs on the operation of the multi‐energy MGs.©2020 IET. This paper is a postprint of a paper submitted to and accepted for publication in IET Renewable Power Generation and is subject to Institution of Engineering and Technology Copyright. The copy of record is available at the IET Digital Library.fi=vertaisarvioitu|en=peerReviewed