Large-scale Grid-connected Photovoltaic Power Plant Research Articles

Performance evaluation of large-scale photovoltaic power plant in Saharan climate of Algeria based on real data

In this study we evaluate a large-scale, grid-connected photovoltaic power plant (LS-PVPP) in a hot climate in Adrar, Algeria. The plant's performance was evaluated using both real-world data from 2018 and simulations conducted with PVsyst in terms of various parameters, such as reference yield, capacity factor, performance ratio, statistical indicators, and carbon emission savings. The results indicate a significant reduction in carbon emissions by the LS-PVPP, with a final yield of 4.98 kWh/kWp/day, a performance ratio of 71.67 %, a capacity factor of 20.72 %, and a global system efficiency of 10.66 % and save 19,388 metric tons of carbon in 2018. The industrial approach analysis revealed a target performance ratio (PR) of 71.17 %. The difference of 0.5 % led to extra energy generation of 252.67 MWh and additional revenue of 27,957.42USD. The simulated data predicted a final yield of 5.36 kWh/kWp/day, a performance ratio of 77 %, a capacity factor of 22.38 %, a global system efficiency of 11.55 %. The aim of this research is to offer data on the performance of a (LS-PVPP) in a hot climate. Researchers, photovoltaic project developers, and stakeholders can utilize the findings to assess project viability, optimize performance, and maximize the environmental and economic benefits.

Why Can Simple Operation and Maintenance (O&M) Practices in Large-Scale Grid-Connected PV Power Plants Play a Key Role in Improving Its Energy Output?

Existing megawatt-scale photovoltaic (PV) power plant producers must understand that simple and low-cost Operation and Maintenance (O&M) practices, even executed by their own personal and supported by a comparison of field data with simulated ones, play a key role in improving the energy outputs of the plant. Based on a currently operating 18 MW PV plant located in an under-developing South-Asia country, we show in this paper that comparing real field data collected with simulated results allows a central vision concerning plant underperformance and valuable indications about the most important predictive maintenances actions for the plant in analysis. Simulations using the globally recognized software PVSyst were first performed to attest to the overall power plant performance. Then, its energy output was predicted using existing ground weather data located at the power plant. Compared with the actual plant’s annual energy output, it was found that it was underperforming by −4.13%, leading to a potential monetary loss of almost 175,000 (EUR)/year. Besides, an analysis of the O&M power plant reports was performed and compared to the best global practices. It was assessed that the tracker systems’ major issues are the forerunner of the most significant PV power plant underperformance. In addition, issues in inverters and combiner boxes were also reported, leading to internal shutdowns. In this case, predictive maintenance and automated plant diagnosis with a bottom-up approach using low-cost data acquisition and processing systems, starting from the strings level, were recommended.

Grid-Connected Photovoltaic Power Plant Without Phase Angle Synchronization Able to Address Fault-Ride-Through Capability

This article discusses the control of large-scale grid-connected photovoltaic power plants (GCPPPs) operating under unbalanced grid voltage sags. The positive and negative sequences of the output currents are controlled to achieve different targets—injecting constant power to the grid or to the ac side of the converter, i.e., including the filter and the grid. Traditionally, synchronization with the grid voltages is required, which is usually performed by a phase-locked-loop (PLL) technique. In this article, the proposed control technique does not require any grid voltage synchronization. An arbitrary angle is used instead with the only requirement of having a frequency equal or close to the grid frequency. The fault-ride-through capability of the GCPPP during unbalanced voltage sags is addressed by proposing a current limiter. Simulation and experimental results verify the performance of the proposed GCPPP.

Flexible Control of Photovoltaic Grid-Connected Cascaded H-Bridge Converters During Unbalanced Voltage Sags

Multilevel cascade H-bridge (CHB) converters are one of the promising solutions for medium- and large-scale grid-connected photovoltaic power plants. However, there is a lack of a complete study about their operation during voltage sags. This paper proposes a flexible control strategy for the operation of photovoltaic grid-connected CHB inverters during unbalanced voltage sags. The key novelty is that the proposed strategy is able to inject both active and reactive powers to the grid with either balanced or unbalanced currents, while ensuring that all dc-link capacitor voltages remain balanced. The simulation and experimental evaluations of a 9-kVA grid-connected seven-level CHB illustrate and validate the performance of the proposed strategy for the operation of the grid-connected CHB converter during different unbalanced voltage sags.

Low‐voltage ride‐thorough capability of photovoltaic grid‐connected neutral‐point‐clamped inverters with active/reactive power injection

Low-voltage ride-thorough capability is among the challenges in the operation of medium- and large-scale grid-connected photovoltaic power plants (PVPPs). In addition, reactive power injection during voltage sags is required by power system operators in order to enhance the voltage of the point of common coupling. The performance of medium- and large-scale grid-connected PVPPs during these events is studied. An algorithm for the calculation of current references, in the dq -frame, during voltage sags is introduced, which considers the inverter current limitation, grid code requirements and the amount of extracted power from photovoltaic strings. The proposed algorithm uses the full current capacity of the inverter in injecting active or reactive powers to the grid during voltage sags, which leads in a better grid voltage enhancement. The performance of proposed control strategies is investigated on a 150-kVA PVPP connected to the 12.47-kV medium-voltage test-case system simulation model during different fault conditions. An experimental setup of the 3.3-kVA grid-connected three-level neutral-point-clamped inverter with a dc/dc converter illustrates and validates the performance of the controller in injecting required active/reactive power and supporting the network voltage.

Research on harmonic and overvoltage of photovoltaic power plant electricity energy collection system based on passive network model

In large-scale photovoltaic (PV) power plant, the output power of each grid-connected inverter is collected by electricity energy collection system and then is put into the grid. Previous studies have demonstrated that the harmonic problem may occur when PV inverters run in parallel even if all the PV inverters output power do individually satisfy the standards. Considering the electricity energy collection system, this study builds the model of harmonic transfer passive network for the typical topological structure of large-scale grid-connected PV power plant, and study the generating mechanism of harmonic and overvoltage. The harmonic power flow of a given calculation example is calculated by using node matrix method and the harmonic voltage magnification of each node is got. The point of common coupling is chosen as the study object. In this study, the impacts of cable parameters, the equivalent impedance of power grid and operation mode of PV power plant on the voltage magnification properties of the transfer network are analysed.

Resonant Versus Conventional Controllers in Grid-Connected Photovoltaic Power Plants Under Unbalanced Grid Voltages

This paper discusses the control of large-scale grid-connected photovoltaic power plant (GCPPP) operating under unbalanced grid voltages. The positive and negative sequences of the grid currents need to be controlled to regulate the power injected into the grid during unbalanced grid voltages. This paper shows that the use of conventional proportional-integral-based controllers compromises stability and dynamic performance of the inverter. The reason is the delays introduced by the filters needed to extract the sequences of the transformed grid currents. Because of such delays, there is a strong restriction on choosing the parameters for the current and voltage controllers, which forces the GCPPP to perform slowly. This can be improved by using resonant controllers instead, which avoid the need for filtering the transformed grid currents. Additionally, a new overcurrent protection is proposed for the GCPPP when it is providing grid voltage support during voltage sags. Simulation and experimental results are presented to evaluate and compare the performance of the GCPPP when operating with the different controllers.

Review of the Influence of Large-scale Grid-connected Photovoltaic Power Plants on Power Grid

With the increase of photovoltaic grid-connected capacity, photovoltaic generation will bring many impacts on distribution network. In this paper, the influence of large-scale grid-connected photovoltaic power plants on power grid is reviewed. First, through researching the basic structure and operating characteristic, the paper introduces the operation mechanism of large-scale grid-connected photovoltaic power plants. Then the paper analyzes the influence of large-scale grid-connected photovoltaic power plants on the grid from the distribution grid planning and scheduling, power quality and power system protection. In the end, the paper summarizes some new problems and discusses and prospects the development trends on the large-scale grid-connected photovoltaic power plants.