Exploring the merits of geographical diversification of solar PV power plants for a resilient PV-dominated electricity grid in India

India is highly dependent on solar photovoltaics(PV)to harness its vast solar resource potential and combat climate change.However,∼90%of the installed PV capacity in India is concentrated in the top nine states,with the remaining states lagging behind.The research reveals that during monsoons,heavy cloud cover and rain lead to high solar resource variability,intermittency and the risk of very low PV generation,which can result in reliability issues in future PV-dominated electricity grids.Although energy storage can help in overcoming high intermittency,there are multiple challenges associated with it.The novelty of this study lies in demonstrating the benefits of combining multiple PV sites in various regions to mitigate the risks of low PV generation and high variability.The variability of individual sites was found to be up to∼3.5 times higher than the variability of combined generation.During noon,prominent solar park sites like Bhadla and NP Kunta experience a decrease in power generation to values as low as∼10%of the rated PV capacity.However,the minimum generation of the large-scale dispersed PV generation is>30%.Furthermore,the research identifies other benefits of dispersing PV generation across the country,viz.,reduction of seasonal variability by adding PV capacity in the southern region,widening of the PV generation span,more room for PV capacity addition,reduction in storage and ramping needs,utilization of hydroelectric potential of the north-east and PV potential of Ladakh,and creating opportunities for sustainable development in rural agrarian regions through agrivoltaics.

Robust stability criteria for uncertain linear systems with interval time-varying delay

This paper considers the robust delay-dependent stability problem of a class of linear uncertain system with interval time-varying delay and proposes less conservative stability criteria for computing the maximum allowable bound of the delay range. Less conservatism of the proposed stability criteria is attributed to the delay-central point method of stability analysis, wherein the delay interval is partitioned into two subintervals of equal length, and the time derivative of a candidate Lyapunov-Krasovskii functional based on delay decomposition technique is evaluated in each of these delay segments. In deriving the stability conditions in LMI framework, neither model transformations nor bounding techniques using free-weighting matrix variables are employed for dealing the cross-terms that emerge from the time derivative of the Lyapunov-Krasovskii functional; instead, they are dealt using tighter integral inequalities. The proposed analysis subsequently yields a stability condition in convex LMI framework that can be solved using standard numerical packages. For deriving robust stability conditions, two categories of system uncertainties, namely, time-varying structured and polytopic-type uncertainties, are considered. The effectiveness of the proposed stability criteria is validated through standard numerical examples.

A model to determine soiling,shading and thermal losses from PV yield data

Apart from being a clean source of energy,photovoltaic(PV)power plants are also a source of income generation for its investors and lenders.Therefore,mitigation of system losses is crucial for economic operation of PV plants.Combined losses due to soiling,shading and temperature in PV plants go as high as 50%.Much of these losses are unaccounted initially,which can jeopardize the economic viability of PV projects.This paper aims to provide a model to determine losses due to soiling,shading and temperature using quantities like irradiance,cell temperature,DC power and current,which are readily available in PV yield data captured by the remote monitoring system,without involving any additional sensors or equipment.In this study,soiling,shading and thermal losses were calculated using PV yield data obtained from a 30-kWp PV plant located in Kharagpur,India.The results showed soiling and shading losses as high as 25.7%and 9.7%,respectively,in the month of December.Soiling loss was verified by measuring transmittance loss of coupon glasses installed in the vicinity of the plant.Shading loss was verified by shadow simulation using an architectural tool(SketchUp).Array thermal loss obtained using the proposed methodology was found to be in line with the estimated value obtained from PVsyst simulation.Additionally,using time-series data,the energy losses corresponding to soiling,shading and temperature effects were calculated by a numerical-integration technique.The monetary loss due to these energy losses thus obtained provides criteria for deciding when to mitigate the sources of these losses.