The enhancement in the storage systems developed by solar thermoelectric centrals brings to this renewable energy a considerable efficiency increase. This improvement propitiates the design of ...storage fluids with lower melting point and higher thermal stability such as molten salt mixtures. This research has broadly studied the HITEC mixture composed by 53 mass% KNO
3
+ 40 mass% NaNO
2
+ 7 mass% NaNO
3
, with the aim to improve the existing solar salt used as energy storage fluid in CSP plants and focus the thermal properties obtained for application in solar linear concentrated technology. HITEC molten salt shows better physicochemical properties than the binary solar salt (60 % NaNO
3
+ 40 % KNO
3
), due to its lower melting point which can improve the work temperature range in commercial solar plants. The tested properties studied by differential scanning calorimeter and thermogravimetric analyser were melting points, heat capacities and thermal stability, mainly. This proposed mixture could be used as heat transfer fluid in solar linear concentrated technology extending the work range temperature between 130 and 550 °C. Results conclude that the main challenge in nitrite salts lies in the need to protect the sample above 350 °C with inert gas, to prevent oxidation of nitrite by oxygen.
The paper analyzes the current state of solar energy for communal needs and the possibility of using it as part of centralized heat supply systems. Helio systems are widely used in the southern ...region for a number of reasons. The use of solar collectors allows you to significantly reduce the heat consumption of buildings in the summer, and sometimes to reduce the use of traditional energy sources to zero. However, in other periods of the year, the share of replacement by traditional solar energy is much lower. In such cases, the question arises as to which heat supply load the system will be designed for - for summer, winter or demi-season. To fulfill the main tasks of the research, an analysis of the main operating methods and software complexes for calculating the operation of the solar system as part of combined heat supply systems was carried out. The main indicators that affect the efficiency of the solar system and recommendations for their selection when calculating the annual heat output are also given. For the centralized heat supply system of the university's buildings, a simulation of the operation of the solar plant throughout the year was carried out. For buildings of different types, storeys, area, purpose, an analysis of the effectiveness of solar systems using different types of solar collectors was carried out with the help of a specialized software complex. The share of heat replacement by solar collectors is shown, which shows the expediency of using solar collectors on a number of buildings.
Solar Power Plants (PLTS) can be composed of many solar panels and connected with many loads at the output. The reliability of an electric power system is the guarantee of an electric power supply ...that can always meet the load (continuity) and the quality of the electricity produced (voltage and frequency). This journal contains the coordination of the Electric Power System with PLTS as an energy source which is monitored for current (I) and voltage (V) so that the output power of the solar panels can be determined and the load settings at the output (adaptive), so that when the input power is maximum, then all loads that have been determined based on priority can enter the system, and when the power drops for example due to nature when the weather is cloudy, the controller will carry out load shedding or disconnection of the load, where the load that must be released first is the one with low priority. The novelty of this study is that the system built is based on the Multiple Sequence Alignment (MSA) algorithm which is used if there is a loose load but it is not in accordance with the priority order, so that the algorithm can determine the appropriate priority sequence decision and work automatically to ensure continuity and qualitygenerated electric power
This paper presents a review of thermal energy storage system design methodologies and the factors to be considered at different hierarchical levels for concentrating solar power (CSP) plants. ...Thermal energy storage forms a key component of a power plant for improvement of its dispatchability. Though there have been many reviews of storage media, there are not many that focus on storage system design along with its integration into the power plant. This paper discusses the thermal energy storage system designs presented in the literature along with thermal and exergy efficiency analyses of various thermal energy storage systems integrated into the power plant. Economic aspects of these systems and the relevant publications in literature are also summarized in this effort.
•The effect of PCM volume fraction for three-layers TES tank is investigated.•A numerical model is used to define the temperature distribution of molten salt.•The thermal/economic performance of the ...three-layers thermocline tank is evaluated.•The bottom PCM layer with a higher VF has the lowest capacity cost of $38/kWh.
The current paper investigates the phase change material (PCM) volume fraction (VF) effect on the thermal and economic behavior of a three-layer thermocline thermal energy storage (TES) tank system which is used in concentrating solar power (CSP) plants. The one dimensional transient dispersion-concentric (D-C) scheme is applied to calculate the phase change inside each capsule. Using MATLAB software, the numerical model equations have been figured out, and the current numerical results have been verified. Four different scenarios have been created to investigate the effect of PCM-VF on the thermal behavior and economic feasibility of the TES tank. The results described that the overall efficiency and the cost of capacity for all cases in order from the case (1) to the case (4) are 80.77%, 64.32%, 73.43%, 85.58%, and $45.37/kWh, $60.49/kWh, $46.28kWh, $38.58/kWh, respectively. Furthermore, case (4) demonstrates the storage capacity of 149 kWh/m3, which is 7.21%, 19.42%, and 15.78% higher than case (1), (2), and (3), respectively. In the comparative study, the results showed that case (4), which has higher VF for the bottom PCM layer, indicates that it is the most viable option of all the studied cases due to its best performance and relatively low cost.
Conventional means of electrical energy generation are costly, create environmental pollution, and demand a high level of maintenance and also going to end one day. This has made it crucial to ...exploit the untapped prospective of the environmentally friendly renewable energy resources. To address this problem, present research proposed an efficient, everlasting, and environment-friendly grid-connected PV system at The Islamia University of Bahawalpur, Pakistan (latitude: 29° 22sup.′ 34sup.″ N, longitude: 71° 44sup.′ 57 E). Bahawalpur is one of those sites where the potential of solar energy is immense. The global daily horizontal solar irradiance at the site is 1745.85kWh/msup.2, having average solar irradiation of 5.9kWh/msup.2 per day, and the ambient average temperature is about 25.7°C. In this research, the performance ratio and different power losses just like soiling, PV module losses, inverter, and losses due to temperature are taken into account and calculated by using PVSyst. The coal saving per day is 15369.3kg which is equal to planting 147600 teak trees over a lifetime. The cost of the energy produced is 0.11 US $/kWh whereas in Pakistan the conventional energy tariff is 0.18 $/kWh. From the simulation results, the value of PR comes out 83.8%, and the CUF value is 16% with a total energy generation of 4908MWh/year. The performance analysis of this grid-connected system would help in the designing, analysis, operation, and maintenance of the new grid-connected systems for different locations.
•DC side faults detection of the solar photovoltaic power plants.•Using Student’s T-Test for outlier detection in photovoltaic power plants.•String level fault detection in large scale solar power ...plants.•Comparison of actual and simulated solar power plant for fault detection.
A new fault detection system is proposed in this study for large-scale grid-tied PV power plants. The fault detection system performs string level comparison of DC power of Actual PV Plant and a simulated PV plant, referred as Theoretical PV Plant. The comparison is performed with a statistical tool which distinguishes a faulty condition and identifies the nature of the fault. This statistical tool is used as outlier detector based on the William Gosset's (Student's) T-Test. The Theoretical PV Plant generates power in a simulation tool using inputs of irradiance and PV module temperature, both obtained from sensors at the Actual PV Plant. The string power of Actual PV Plant is also obtained in the simulation from the data logger in real-time environment. These string powers of Actual and Theoretical PV Plants are compared to find a faulty condition. A GUI is developed where the fault alarms appear on Real-time Status Monitor whenever a fault occurs in the Actual PV Plant. The proposed fault detection system has been validated on a 125 kWp grid-connected PV plant.
The solar radiation near the surface is the main reason that affects photovoltaic power generation. Accurate ultra‐short‐term solar radiation prediction is the premise of photovoltaic power ...generation prediction. Here the cloud movement prediction method based on the ground‐based cloud images is presented. The cloud recognition, cloud matching, cloud area correction and cloud movement prediction are performed to predict the drift trajectory of the clouds that will block the sun. Then, using digital image technology, 13 kinds of feature information are extracted from the ground‐based cloud images. Then, these feature information are input into BP neural network, and the parameters of BP neural network are optimized by genetic algorithm. Through a large number of data training, a new ultra‐short‐term prediction model of solar radiation is established. Finally, through experimental comparison, the results show that the prediction accuracy of the model with the feature information of ground‐based cloud images can reach 96%, compared with the model without the feature information of ground‐based cloud images, the accuracy is improved by 5%. The proposed ultra‐short‐term solar radiation prediction model can effectively predict the radiation jumping process caused by cloud occlusion, and greatly improve the prediction accuracy, especially in cloudy weather.
A large-scale solar power plant costs a lot of money in the early stage of development and is greatly affected by the natural environment. Therefore, efficient operation is very important. The ...purpose of this study is to analyze the cleaning effect of photovoltaic modules according to precipitation during the operation stage of a large-scale solar power plant. The first analysis compared ‘average power generation on sunny days under standard cloudiness from after precipitation to the next precipitation’ and ‘average daily power generation per quarter’ and confirmed that precipitation had an effect on increasing power generation by 26%. The second analysis compared ‘average power generation on sunny days under the standard cloudiness from after precipitation to the next precipitation’ and ‘average daily power generation on a clear day just before precipitation’. It was confirmed that the average power generation efficiency of the entire sample increased by 4.8% on average after precipitation than before precipitation. This study quantitatively analyzed the cleaning effect of photovoltaic modules by precipitation through actual power generation data of large-scale solar power plants. This study has sufficient value in establishing an operation manual for decision-making on the appropriate input cost for cleaning photovoltaic modules and improvement of power generation efficiency.
PDF
