Large-scale PV Power Plants Research Articles

Evaluation of a grid-connected PV power plant: performance and agrivoltaic aspects

AbstractThe performance ratio, a globally recognized metric that correlates with reported global solar radiation values, serves as a crucial indicator for evaluating the efficiency of grid-connected PV plants. Also, a large scale PV power plant alone can afford some agricultural irrigation energy requirement of a region. In this study, the actual generation data from a power plant located in Bursa province in northwestern Türkiye, during its initial six years of operation have been analyzed. The analysis reveals that the annual electricity production of the power station reaches approximately 10 GWh. Notably, the time period between April and September witnesses a monthly electricity generation exceeding 1 GWh, with September emerging as the most productive month, characterized by an average performance ratio of 94.5% during this six-year period. However, over the span of six years, the highest average electricity generation occurs in July, peaking at 1.34 GWh. Also, the power plant alone can meet the agricultural irrigation energy requirement of the region in the range of 6.7–2.3%. From an environmental impact and global warming perspective, it is noteworthy that during the 36-month period in the summer season, the performance ratio exceeded 100% only three times. However, within the 32-month period in the winter season, the performance ratio exceeded 100% 19 times. This situation indicates that while the reported radiation rates by the managements are consistent with the actual values for the summer months, they need to be revised, especially for the winter months.

Bi-objective Pareto optimization for clustering-based hierarchical power control in a large-scale PV power plant

To assist the power grid for the real-time power balance, more and more PV power plants have participated in automatic generation control (AGC). In this process, a PV power plant should distribute the dynamic total AGC signal to all the controllable inverters. Firstly, it is difficult to satisfy multiple operation requirements for the whole PV power plant. Secondly, it easily results in a high optimization complexity due to the large amount of controllable inverters, especially for a large-scale PV power plant. To handle these two problems, a clustering-based hierarchical power control is constructed with two conflict objectives, including the AGC responding performance and the reactive power reserve. With the discrepant responding performance of different inverters, all the inverters are clustered into multiple groups by the K-medoids algorithm according to their regulation parameters. Hence, the hierarchical power control contains a top-layer control and a bottom-layer control. An efficient non-dominated sorting genetic algorithm is adopted to acquire the Pareto optimal solutions for the top-layer control, then the bottom-layer control is implemented in proportion to their regulation capacities. Finally, the case studies are carried out to verify the proposed technique for a large-scale PV power plant under different AGC signals and dynamic irradiations.

A method for monitoring the solar resources of high-scale photovoltaic power plants based on wireless sensor networks

This paper optimizes the layout design of optical resource monitoring node networks via a comprehensive evaluation standard composed of the shortest network path, coverage and time-space zoning and ensures the optimal economic and reasonable layout of the monitoring network. At the same time, this paper presents a method, such as Zigbee and fourth generation (4G) designs, for monitoring the solar resources of large PV power stations based on wireless sensor technologies and implements a solar resource monitoring system of a large-scale PV power plant group based on wireless sensor technology. Compared with the solar resource monitoring networks before optimization, the optimal layout and wireless sensor networks have less redundancy of information through correlation analysis and rotational empirical orthogonal function (REOF). The reliability and coverage increase by using the theory of the shortest network path to select routing nodes and decide the effective coverage range. Through theoretical analysis and empirical verification, it is also shown that the proposed optimal layout of the solar resource monitoring network can meet the assessment accuracy of the power generation capability of large-scale PV power station groups and provide a reference for the expansion planning of large-scale PV power station groups.

DC optimizer-based decentralized frequency support scheme of large-scale PV plants considering partial shading conditions

Solar energy loss of the large-scale PV power plant (LPVPP) caused by partial shading can be mitigated by unit-level DC optimizers (DCO). This paper presents a novel DCO-based decentralized control (DBDC) scheme for an LPVPP to provide active frequency support without equipping energy storage. The proposed DBDC scheme consists of two levels: the plant-level modified DC-link voltage control for the PV inverter and the unit-level improved virtual inertia control and lookup table-based droop control deployed in the DCO controller for each PV generation unit. The stored energy of the DC-link capacitor can be adjusted for inertia emulation based on grid frequency fluctuation with plant-level voltage control. Meanwhile, the frequency deviation is converted into the changes of DCO output voltages. Then, according to the voltage deviations of DCOs, the adaptive power adjustment for PV units is realized through unit-level virtual inertia and droop control scheme. Finally, the maximum use of the PV reserve power and the proposed DBDC scheme without using any communication network can be achieved for LPVPPs, even under frequent partial shading conditions. Case studies are undertaken on a PV-integrated two-area system. Comparison simulation results verify the effectiveness and universality of the proposed DBDC scheme under different scenarios.

Very Large Scale PV Power Generation for Shifting to a Renewable Energy Future

In order to meet the environmental challenge in the 21st Century, renewable energy must play an important role. PV is one of the most promising renewable energy technologies. It may be no exaggeration to say that we’re now coming to the stage of energy transition by PV power plants. PV power plants came on the market first in the latter half of 2000s. Since then, a capacity of the largest PV power plant in the world has been broken every year. In 2014, some PV plants over 500MW started operation. Currently, a share of PV power plants will be 15% or more of the total PV installation in the world. The technical and economic feasibility of the large scale PV power plants are already proven, and the environmental and socio-economic benefits can make the project more attractive. To deploy large scale PV power plants as a major power source, the feasibility and expected benefits of PV power plants are analysed, as well as a potential for global energy system.

Simplified model of battery energy-stored quasi-Z-source inverter-based photovoltaic power plant with Twofold energy management system

The use of a battery energy-stored quasi-Z-source inverter (BES-qZSI) for large-scale PV power plants exhibits promising features due to the combination of qZSI and battery as energy storage system, such as single-stage power conversion (without additional DC/DC boost converter), improvements in the output waveform quality (due to the elimination of switching dead time), and continuous and smooth delivery of energy to the grid (through the battery energy storage system). This paper presents a new simplified model of a BES-qZSI to represent the converter dynamics with sufficient accuracy while using a less complex model than the detailed model (including the modelling of all switches and switching pulses). It is based on averaged values of the variables, voltage/current sources, and the same control circuit than the detailed model, except for the switching pulses generation. The simplified model enables faster time-domain simulation and is useful for control design and dynamic analysis purposes. Additionally, an energy management system has been developed to govern the power supply to grid under two possible scenarios: 1) System operator command following; or 2) economic dispatch of the stored energy. The results obtained from simulations and experimental hardware-in-the-loop (HIL) setup for different operating conditions of the grid-connected large-scale PV power plant with battery energy storage under study demonstrate the validity of the proposed simplified model to represent the dynamics of the converter and PV power plant for steady-state stability studies, long-term simulations, or large electric power systems.

Five-Year Performance of an ESE Lightning Protection System for a Large Scale PV Power Plant in Thailand

This article presents a five-year performance review of an early streamer emission (ESE) air terminal lightning protection system for a large scale PV power plant in Thailand. The comparison effect of a Franklin lightning protection system and the ESE lightning protection system was analyzed for the PV power plant. The ESE lightning protection system was selected to be implemented in the PV power plant. The capacity of the PV power plant studied was 8 MWp on an area of 150,000 square meters in the Nong Ya Plong district, Phetchaburi province, Western Thailand. A Franklin lightning rod type was also designed to be implemented in this PV power plant. The Franklin lightning rod type comprised 122 pieces but the ESE lightning rod type consisted of only 11 pieces. The conceptual design of the Franklin rod type followed the standard of the Council of Engineers, Thailand, and the ESE lightning rod type followed the NFC17102 standard of France. The estimated cost of installation was a key comparison to select the lightning protection system; the total installation cost of the Franklin lightning rod type was USD 197,363.80 and the ESE lightning rod type was USD 44,338.06. The lightning system was applied to the lightning arrester in the power plant to provide good protection, in which the balance of the pole to the mounting position is required to optimize the system performance. The result of the simulation also showed that the shading effects of the Franklin rod type were greater than the ESE rod type. The installation cost of the Franklin lightning rod type was 4.45 times more expensive than the ESE lightning rod type. Therefore, the ESE lightning protection system was selected to be implemented in the PV power plant. From the recorded data of the five-year performance of the ESE lightning protection system (2016–2020), there were three occurrences of a lightning strike on the PV power plant. The ESE lightning protection system effectively protected and prevented the lightning strike to the PV power plant. This study can help and support with the selection of a lightning system for the protection of large scale PV power plants in the future.

A Random Forest-Assisted Fast Distributed Auction-Based Algorithm for Hierarchical Coordinated Power Control in a Large-Scale PV Power Plant

In response to the automatic generation control (AGC) signals, the direct power control of a large-scale PV power plant easily encounters the communication bottlenecks, the high optimization difficulty and computation burden due to the large number of controllable inverters with different response performances. To handle these problems, a hierarchical framework of coordinated power control (CPC) is constructed, which is decomposed into a upper-layer CPC between different sub-areas and a lower-layer CPC between different inverters in each sub-area. Instead of a centralized optimization, a novel random forest-assisted fast distributed auction-based algorithm (FDAA) is proposed for a distributed optimization of CPC. The random forest can rapidly generate a dynamic surrogate model of the optimization results from the low-layer CPC to the upper-layer CPC, thus these two-layer optimizations of CPC can be decoupled without too much interactions and computations. The effectiveness of the proposed method is thoroughly evaluated on a PV power plant with 10 sub-areas and 100 inverters under various irradiation conditions.

Socio-inspired democratic political algorithm for optimal PV array reconfiguration to mitigate partial shading

Time-varying environment conditions have significantly influenced operation performance of photovoltaic generation. Partial shading condition is a typical problem which usually increases mismatch losses and reduces output power of photovoltaic array. For large-scale PV power plants, partial shading may affect the efficiency of the entire PV system. To solve this issue, this paper proposes a novel socio-inspired photovoltaic reconfiguration approach, called democratic political algorithm (DPA), which can effectively reduce power losses, improve power generation efficiency and accelerate convergence rate. DPA aims to reconfigure photovoltaic array’s electrical connection to minimize malignant impacts from partial shading condition and then obtain higher-quality output characteristics. Three case studies are carried out to verify the effectiveness and advantages of DPA, together with a thorough comparison of nine typical meta-heuristic algorithms. Simulation results demonstrate that DPA can enhance output power of photovoltaic array by 21.47% for a 10 × 10 (small) PV array, 21.55% for a 15 × 15 (medium) PV array, and 20.98% for a 20 × 20 (large) PV array compared to total cross tied interconnection scheme.

Comparison on Economics and Performance of Large Scale PV Power Plants: a Case Study

This paper compares the energy generation of two large-scale PV power plants at a rate of 6 MW. Economics and performances are the two main analysis viewpoints for the comparison of the system efficiency and profit of two types PV panel for a service period of twenty-five years. Thin-film and polycrystalline PV power plants have been studied. In the simulation results, three years of actual collected data have been analysed and compared. The PVsyst program has been used to simulate the performance ratio (PR) and the energy production. In addition, the net present value (NPV) has been also used to analyse the economic efficiency. The simulation results have showed that in the case of thin-film PV panels, the energy production in the beginning of the year has been higher than the actual collected data. On the other hand, in the case of polycrystalline PV panels, the energy production has been lower than the actual collected data. By the long term economic efficiency, the results have showed that the efficiency of polycrystalline PV panels has been better than the one of thin-film PV panels. Therefore, the obtained results from this work may be used as a guideline for deciding to invest in the PV power plant in the future.

PV array and inverter optimum sizing for grid-connected photovoltaic power plants using optimization design

This paper aims to select the optimum inverter size for large-scale PV power plants grid-connected based on the optimum combination between PV array and inverter, among several possible combinations. Inverters used in this proposed methodology have high-efficiency conversion in the range of 98.5% which is largely used in real large-scale PV power plants to increase the financial benefits by injecting maximum energy into the grid. To investigate the PV array-inverter sizing ratio, many PV power plants rated power are considered. The proposed method is based on the modelling of several parts of the PV power plant taking into account many design variables and constraints. The objective function is the levelized cost of energy (LCOE) and the optimization is performed by a multi-verse algorithm. The optimization method results in an optimum inverter size that depends on the PV plant rated capacity by providing an optimum number of inverters required in the installation site. The optimum sizing ratio (Rs) between PV array and inverter were found equal to 0.928, 0.904, and 0.871 for 1 MW, 1.5 MW, and more than 2 MW, respectively, whereas the total power losses reached 8% of the total energy generation during the PV power plant operational lifetime.

Real-time fault detection system for large scale grid integrated solar photovoltaic power plants

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.

Solar PV Microgrids Implementation model: A case study of Local Self Governments in the Indian State of Kerala

The State of Kerala in Southern part of India has significant potential for generation of power from renewable energy sources, especially solar energy. Most of the PV projects in the State are being implemented on roof-tops due to the unavailability of land area in the densely populated State for large utility scale PV power plants. The concept of implementing Solar PV projects by empowering Local Self Governments has been explained in this paper by illustrating the case study of the Indian State of Kerala. The respective Local Self Governments like Municipal Corporations are playing a key role in Kerala in this decision-making process to accomplish model carbon free solar communities by installing Solar Photovoltaic Projects. The requirement of local beneficiary will be analysed by local trained experts and feasibility study will be conducted for the beneficiary communities involving residential buildings, local industries and commercial institutions and educational institutions and the PV projects will be implemented utilising the local E.P.C players. Local Self Governments like Municipal Corporations were empowered to plan, formulate and implement their own Solar Photovoltaic Projects. This approach is being implemented in Kerala resulting in solar electrification of local communities/institutions through the decentralised approach. This created a new business model at the local level involving trained manpower and supply chain for meeting the Local Self Government targets for new PV projects in order to achieve the targets of carbon free communities.

Energy Storage Sizing Optimization for Large-Scale PV Power Plant

The optimal configuration of energy storage capacity is an important issue for large scale solar systems. a strategy for optimal allocation of energy storage is proposed in this paper. First various scenarios and their value of energy storage in PV applications are discussed. Then a double-layer decision architecture is proposed in this article. Net present value, investment payback period, internal rate of return are taken as the outer objective function, energy storage capacity is the optimal variables. The investment cost of energy storage system is taken as the inner objective function, the charge and discharge strategy of the energy storage system and augmentation are the optimal variables. Finally, the effectiveness and feasibility of the proposed model and method are verified through case simulations. The results show that the comprehensive evaluation index can be aimed at the concerns of energy storage investors, comprehensively evaluate the feasibility of the energy storage project, and obtain the corresponding energy storage scale when the comprehensive evaluation index is the highest.

Effect of Solar Tracking on the Economic Viability of a Large-Scale PV Power Plant

Abstract This paper evaluated the economic potential of three different photovoltaic energy technologies at a selected site, Wa, in the Upper West region of Ghana. The cost of energy and net present value metrics were used to ascertain the cost-effectiveness of these technologies (fixed, single and double axis tracker systems). From the analysis, all three technologies are economically viable at the selected site, however, a sensitivity analysis shows that the fixed axis tracker is unviable at a discount rate above 2 % whiles that of the single and double axis power plants also become impracticable at a discount rate above 6 % using the financial input parameters adopted for the study. This is an indication that, even though the selected site may have the required solar radiation for the development of large-scale PV power plant, there is the need to create the necessary conducive financial environment to enable such projects to become viable. The double axis tracking system was identified as the optimum system that should be deployed at the selected site to get the best in terms of affordability of electricity to consumers and equity payback.

Modeling and quantifying dust accumulation impact on PV module performance

Natural dust accumulation or soiling on the surfaces of PV modules in large-scale PV power plants has a significant effect on the overall performance of these power plants, especially those located in arid areas such Jordan. In this manuscript, the soiling induced effects are quantified and modeled. Experimental setups for three common types of PV modules are utilized to acquire the data used for the models. Projection of the performance and economic impacts on large scale PV plants is carried out to emphasize the necessity to consider the soiling effects during the planning phase. Optimization of PV cleaning schedules for the best return-on-investment, in addition to the importance of determining typical soiling rates for forecasting models in PV power plants under planning is presented as well.

Studies on PV power plant designing to fulfil the energy demand of small community in Poland

Although the total energy production from fossil fuels in Poland has been decreasing for the past few years, still at least 80% of the total energy consumption derives from coal. To reduce this high consumption rate alternative energy sources should be developed. One of the most promising is photovoltaics. This paper presents modeling studies of large scale PV power plant design to fulfil the electricity needs of a small community located in Poland. Based on the energy demand prognosis and monthly solar radiation data PV power plant capacity and a number of modules were computed. The distance between rows of the modules was also determined to avoid the shadowing effect. System configuration and energy production simulations were carried out using DDS-Cad software. Results of energy calculations were compared with the yearly energy needs of the studied community. Reduction of greenhouse gases emission was estimated. Modeling results show that proposed 3.1 MWp photovoltaic plant can produce enough energy to fulfil the yearly energy demand of the households in the studied area. Moreover, significant reduction of CO2 emission and other gaseous pollutants were observed.

Voltage prevention and emergency coordinated control strategy for photovoltaic power plants considering reactive power allocation

This paper proposes a voltage prevention and emergency control strategy that consists of coordinately arranging multiple reactive power sources in order to handle the point of common coupling (PCC) voltage fluctuation and stability in large-scale PV power plants. When a disturbance occurs at the PCC, dynamic reactive power compensation devices are coordinated preferentially to support the PCC voltage. After the disturbance is cleared, the reactive power in dynamic and fast devices is transferred into static and slow devices so that the static VAR generation (SVG) can maintain a large power margin for coping with the next disturbance. Moreover, the reactive power output of the individual inverter in PV power plants is coordinately allocated using a model to optimize the in-station voltage distribution. Finally, the effectiveness of the proposed control strategy is verified by an example simulation of a practical large-scale PV power plant.

A guide in installing large-scale PV power plant for self consumption mechanism

The objective of this study is to optimize the design of a large scale photovoltaic power plant. A methodology is proposed to guide the investors and technical staff in the design of such a system, with core emphasis on self-consumption policy. A flowchart of the process, that uses site survey, system components, associated costs, meteorological data, load analysis, is created. The optimum capacity of a large-scale PV power plant is determined by an iterative approach as stated in the flowchart, which considers the payback period as the decision criterion. A case study is carried out in Cyprus International University (CIU) in order to support the proposed methodology. The dynamics of this study is unique, in that, the policy governing Renewable Energy Sources in Northern Cyprus does not allow the electricity authority to provide value for the electricity fed into the grid by self-consumption renewable energies. Simulations are performed by PV∗SOL for different capacities varying from 450 to 1250kWp. Two different analyses have been conducted by considering the current and the predicted electricity demand of CIU. As a result, two optimum system sizes for current and predicted demands are obtained as 850kWp and 1200kWp respectively.

Fault Transient Analysis and Protection Performance Evaluation within a Large-scale PV Power Plant

In this paper, a short-circuit test within a large-scale PV power plant with a total capacity of 850MWp is discussed. The fault currents supplied by the PV generation units are presented and analysed. According to the fault behaviour, the existing protection coordination principles with the plant are considered and their performances are evaluated. Moreover, these protections are examined in simulation platform under different operating situations. A simple measure with communication system is proposed to deal with the foreseeable problem about the current protection scheme in the PV power plant.