PV Distribution Research Articles

Evaluation of Power Characteristics under Constant PCS Power Factor Operation in PV Distribution Line

Evaluation of Power Characteristics under Constant PCS Power Factor Operation in PV Distribution Line

Optimization study of overvoltage problem in PV distribution network based on electrical energy router

Photovoltaic power generation has the advantages of being clean and efficient, but it poses a threat to the voltage quality of distribution networks due to unstable power output. In order to solve the overvoltage and power utilization problems of a high-penetration PV distribution network, this paper proposes a tidal current analysis model based on a four-port power router. First, the steady-state modeling of different ports of the electrical energy router is carried out, and the corresponding voltage control strategy is proposed. Then, by establishing a unified tidal current calculation model, a solution for the optimal operation of the distribution network is proposed. Finally, based on the overvoltage data of a regional power grid, the impact on the voltage level of the grid-connected PV system before and after the addition of the power router is compared. From the analyzed data, it is concluded that the introduction of a four-port power router for corresponding port control strategies can effectively improve overvoltage problems in high-permeability PV distribution networks.

Geographic-information-based stochastic optimization model for multi-microgrid planning

This paper presents a model for the realistic planning of multi-microgrids in the context of Active Distribution Networks with the assistance of Geographic Information Systems. The model considers the distribution system grid as well as the geographic features of the Region of Interest. It also includes long-term purchase decisions and short-term operational constraints, and considers uncertainties associated with electricity demand and Renewable Energy Resources using an existing Two-Stage Stochastic Programming approach. Geographic Information Systems along with Deep Learning are used to estimate the areas of rooftops within the Region of Interest and model the Low Voltage grid. The planning model is used to study the feasibility of implementing a multi-microgrid system consisting of 4 individual microgrids at an Active Distribution Network in a municipality in the state of São Paulo, Brazil. The results of the model presented in this paper are compared with the results obtained using Monte Carlo Simulations and an existing, less detailed, Two Stage Stochastic model. It is demonstrated that the stochastic solutions are close to those obtained with Monte Carlo at a lower computational cost, and that the use of Geographic Information allows to determine both the capacity and location of the PV panels, batteries, and distribution transformers on the microgrids grid, thus providing more precise and useful planning results.

PV Distribution Network Planning Method Considering the Cost and Effectiveness of Voltage Control

The large-scale grid connection of distributed power sources can save energy, reduce emissions, and improve the flexibility of the power supply, but the volatility and uncertainty of its power output lead to voltage fluctuations and power quality problems, among which voltage problems have become an important factor inhibiting the large-scale access of distributed power sources, posing new challenges to the grid planning and operation. To address the grid voltage crossing problem after PV grid connection, firstly, a multi-time scale voltage control model based on voltage control coefficients is established to achieve maximum network safety and economic satisfaction; the problem is then solved using a variety of group traction differential evolutionary algorithms with the objective function being the minimum annual integrated cost and the maximum percentage of clean energy generation. This method offers a strong theoretical and technical guarantee for the planning of distributed power access to the distribution system.

Determinants of the distribution of utility-scale photovoltaic power facilities across the globe

Photovoltaic power (PV) is the fastest-growing source of renewable electricity. Making reliable scenarios of PV deployment requires information on what drives the spatial distribution of PV facilities. Here we empirically derive the determinants of the distribution of utility-scale PV facilities across six continents, using a mixed effects logistic regression modelling approach relating the occurrence of over 10 000 PV facilities to a set of potential determinants as well as accounting for country and spatially correlated random effects. Our regression models explain the distribution of PV facilities with high accuracy, with travel times to settlements and irradiation as the main determinants. In contrast, our results suggest that land cover types are not strong determinants of the PV distribution, except for Asia and Africa where the PV distribution is related to the presence of agriculture, short natural vegetation and bare land. For Europe and Asia a considerable part of the variance in PV distribution is explained by inter-country differences in factors not included in our fixed determinants. Relevant determinants identified in our study are in line with the main assumptions made in cost of electricity (COE) maps used in the IMAGE integrated assessment model (IAM). However, we found correlations (Spearman ρ) of −0.18–0.54 between our PV probability maps and IMAGE’s COE maps. These may partly be explained by conceptual differences between our empirically-derived probability maps and the COE maps, but we also recommend using higher-resolution maps of PV potential and COE computations such as used in IAMs.

Research on intelligent photovoltaic control and protection switch based on fuzzy PID controller

In recent years, intelligent electrical equipment has been widely used. Control and protection switches (CPS) have the functions of circuit breakers, relays, disconnectors and many other products, etc. The intelligent PV low-voltage switch based on fuzzy PID controller designed in this study is applicable to the low-voltage PV distribution network with rated voltage of 500V and rated current up to 1200A with direct grounding of the neutral point of three four wires. The intelligent photovoltaic low-voltage switch designed in this paper can provide indirect contact protection to the distribution network, which can reduce the occurrence of grounding accidents caused by equipment insulation damage; the intelligent photovoltaic low-voltage switch designed in this paper is equipped with a wireless transmission module, which applies the wireless communication technology to the power equipment, so that the power equipment can realize the functions of remote monitoring the operation status of the power grid and controlling the switch breaking and closing. Finally, the fuzzy PID controller is introduced to improve the reliability of switch operation.

Optimal siting and sizing of hybrid PV and wind energy distribution network

Optimal siting and sizing of hybrid PV and wind energy distribution network

Maximum Energy Penetration Rate of PV in Distribution Network Under Security Constraints Based on Game Theory

The high penetration of PV incurs voltage violation and power flow reversion in distribution network. A numerical definition of energy penetration rate (EPR) is proposed to measure the penetration of PV. A comprehensive security index (CSI) considering both the voltage and power flow constraints is also presented as the criteria for calculating the maximum value of EPR (MEPR). In power market, the PV owner and distribution system operator (DSO) pursue profit by optimizing their installed infrastructure capacity separately. Both cooperative and non-cooperative game theories are adopted to model their strategies. The Shapley value is used as the payoff allocation method for the alliance. A linear programming is presented when the Shapley value is unstable. The capacity planning strategy of players are obtained based on grey wolf algorithm (GWA). The MEPR is achieved by increasing the maximum allowed PV capacity at each bus step by step until the CSI gets worse. Finally, the MEPRs of several distribution networks are calculated. Some impactful factors and comparison are also discussed in detail.

The claustrum of the sheep and its connections to the visual cortex.

The present study analyses the organization and selected neurochemical features of the claustrum and visual cortex of the sheep, based on the patterns of calcium-binding proteins expression. Connections of the claustrum with the visual cortex have been studied by tractography. Parvalbumin-immunoreactive (PV-ir) and Calbindin-immunoreactive (CB-ir) cell bodies increased along the rostro-caudal axis of the nucleus. Calretinin (CR)-labeled somata were few and evenly distributed along the rostro-caudal axis. PV and CB distribution in the visual cortex was characterized by larger round and multipolar cells for PV, and more bitufted neurons for CB. The staining pattern for PV was the opposite of that of CR, which showed densely stained but rare cell bodies. Tractography shows the existence of connections with the caudal visual cortex. However, we detected no contralateral projection in the visuo-claustral interconnections. Since sheep and goats have laterally placed eyes and a limited binocular vision, the absence of contralateral projections could be of prime importance if confirmed by other studies, to rule out the role of the claustrum in stereopsis.

Retrieving Spatial Variation of Land Surface Temperature Based on Landsat OLI/TIRS: A Case of Southern part of Jember, Java, Indonesia

The study analysis of the land surface temperature (LST) is crucial to maintain the environmental quality of climatic conditions, particularly in Jember as the forest buffer region in the eastern part of Java, Indonesia. In this paper, the land surface temperature (LST) distributions were investigated using Landsat 8 OLI/TIRS images in about 24,008.67 ha of the southern part of Jember. The land surface emissivity (LSE) is also provided in deriving the land surface temperature (LST) from satellite images. The LSE value in the Earth’s surface is retrieved from NDVI (Normalized Difference Vegetation Index) and fractional vegetation cover (Pv). In this case, the reflectance of NIR (Near Infrared) and red bands of Landsat 8 OLI sensor have been acquired to derive NDVI and Pv distribution. Therefore, the LST can be obtained from the LSE coefficient result and brightness temperature (BT) of Landsat 8 TIRS. The results showed that the LST average in the study area increased significantly from 20°C in 2013 to 26°C in 2018. This condition was triggered by the decreasing area with a high vegetation density about 5% of the study area from 2013 to 2018, which was figured out from the spatial distribution of NDVI and LSE.

Design of Optimal Power Point Tracking Controller Using Forecasted Photovoltaic Power and Demand

With the advent of grid-connected photovoltaic systems for energy generation, new technologies must be created that maintain a continuous and stable balance between supply and demand of generated electricity. Consequently, accurate prediction of solar energy generation and consumption is required. Solar energy generation and electric power demand are both stochastic and nonstationary in nature and often incongruous. The imbalance between demand and supply can be costly and leads to long-term ineffectiveness of power generation and distribution. The aim of this work is to propose methods for maintaining demand-supply balance in PV power generation and distribution systems. To achieve this, we build and combine three different tools: 1) a predictive model for forecasting solar energy generation, 2) a predictive model for demand prediction, and 3) a real-time control algorithm that uses the outputs of prediction models and adjusts the output voltage of PV system to maintain demand-supply balance. Our prediction models are based on time-series forecasting tools and artificial neural networks. The control algorithm is called optimal power point tracking (OPPT) and is based on the perturb and observe algorithm. We evaluate the performance of the combined prediction-controller system using real-world data.

Community Based Solar PV Distribution Model in Eastern Kenya: Success Factors and Challenges

Community Based Solar PV Distribution Model in Eastern Kenya: Success Factors and Challenges

Modelling of a Micro Grid PV Rooftop System by PSCAD

A Photovoltaic rooftop system is being grown up for producing electricity in Thailand. The technical study of PV rooftop system is required especially in term of power quality impact from PV rooftop system to the grid system. The aim of this paper is to construct the simulation models of a micro grid PV rooftop system by using the simulation software PSCAD. PSCAD has an advantage that the software provides a complete model of the PV rooftop system in an electromagnetic transient software environment. The modules of study include PV array, three-phase inverter, LC filter, transformer, load, and distribution network. The constructed model is simulated under the Provincial Electricity Authority (PEA) regulations.

Analysis of the Impact of Distributed Grid-Connected PV System on Power Quality of the Electrical Distribution Network

Electricity generation from solar energy by using PV cells is drastically increased due to global warming concern, greenhouse effect, and quality of living standards. However, PV generation may offer variable and unpredictable energy output due to intermittent nature of solar irradiance and hence, integration of PV into grid may provide some drawback effect to the power system. The aim of this paper is to investigate the impact of grid connected PV system on the power quality of distribution network. The power quality analysis is based on real measurements of 10 kWp, Energy Park SERT, School of Renewable Energy, Naresuan University, Thailand. Parameters such as active and reactive power, voltage, current, power factor, THDv, THDi, individual harmonic voltage and harmonic current are observed for the investigation of the interaction between SERT PV system and distribution network’s power quality. According to the measured data, PV system operation is negligible in terms of voltage distortion, voltage magnitude and frequency variation. Therefore, it can be noticed that 10 kWp SERT PV system does not effect on the distribution system power quality due to low PV penetration level.

Research on Peak Capacity of Distributed Photovoltaic Generation Based on Voltage Deviation Model in Distribution Network

Large-scale grid-connected photovoltaic generators will cause out-of-limit of voltage deviation. The model of voltage drop caused by loads and voltage rise caused by PV generators are established under different loads or PV distribution modes along the line, and the maximum allowable capacity of PV power injected into the grid without causing over-voltage is calculated, assuming the bus voltage deviation reaching the upper limit. The maximum PV penetration level of typical distribution lines is derived under the condition that PV generators is of the same distribution mode with loads, and the voltage margin at the head end of the line without causing over-voltage is proposed. The results show that over-headlines can carry much more PV power than cables, and over-voltage will be avoided by controlling the PV power according to the connected bus voltage, and suitably lowering the bus voltage will allow more PV to connect into the grid.

Solar Photovoltaic Inverter Current Distribution during Fault on Distribution and Transmission System

To facilitate more extensive adoption of renewable distributed electric generation, the U.S. Department of Energy launched the Renewable Systems Interconnection (RSI) study during the spring of 2007. The study addressed the technical and analytical challenges that must be addressed to enable high penetration levels of distributed renewable energy technologies. Interest in PV systems is increasing and the installation of large PV systems or large groups of PV systems that are interactive with the utility grid is accelerating, so the compatibility of higher levels of distributed generation needs to be ensured and the grid infrastructure protected. The variability and non dispatch ability of today’s PV systems affect the stability of the utility grid and the economics of the PV and energy distribution systems. Integration issues need to be addressed from the distributed PV system side and from the utility side. Advanced inverter, controller, and interconnection technology development must produce hardware that allows PV to operate safely with the utility and act as a grid resource that provides benefits to both the grid and the owner.

An Analysis on Smoothing Effect of PV Distribution by using Measurement Data of Sakai Solar Power Plant

An Analysis on Smoothing Effect of PV Distribution by using Measurement Data of Sakai Solar Power Plant

Positive Effect of PV's Constant Leading Power-Factor Operation in Power System

Overvoltage problem due to highly penetrated photovoltaic power generation (PV) has been regarded as the foremost concern in distribution network. To find an economical solution for the problem, the authors focus in the inherent ability of present distribution network and PV, and examine whether PV's Constant Leading Power-Factor Operation can mitigate the overvoltage problem enough or not. Simulation based on accurate distribution system model, which is aggregated from many loads/PV using Y-connection aggregation method, has revealed that combination of PV's Constant Leading Power-Factor Operation and distribution transformer's Line voltage Drop Compensator (LDC) has important positive effects for solving the problem. Distribution system voltage is kept within the statutory voltage. Frequency of PV output restriction due to overvoltage is reduced. Frequency of tap change on on-Load Tap Changer (LTC) and Step Voltage Regulator (SVR) is also reduced. In addition, no negative effects are recognized in trunk power system.

Diagnosing Snowband Predictability Using a Multimodel Ensemble System

Abstract The forecast uncertainty of mesoscale snowband formation and evolution is compared using predictions from a 16-member multimodel ensemble at 12-km grid spacing for the 25 December 2002, 12 February 2006, and 14 February 2007 northeast U.S. snowstorms. Using these predictions, the case-to-case variability in the predictability of band formation and evolution is demonstrated. Feature-based uncertainty information is also presented as an example of what may be operationally feasible from postprocessing information from future short-range ensemble forecast systems. Additionally, the initial condition sensitivity of band location in each case is explored by contrasting the forecast evolutions of initial condition members with large differences in snowband positions. Considerable uncertainty in the occurrence, and especially timing and location, of band formation and subsequent evolution was found, even at forecast projections <24 h. The ensemble provided quantitative mesoscale band uncertainty information, and differentiated between high-predictability (14 February 2007) and low-predictability (12 February 2006) cases. Among the three cases, large (small) initial differences in the upper-level PV distribution and surface mean sea level pressure of the incipient cyclone were associated with large (small) differences in forecast snowband locations, suggesting that case-to-case differences in predictability may be related to the quality of the initial conditions. The complexity of the initial flow may also be a discriminator. Error growth was evident in each case, consistent with previous mesoscale predictability research, but predictability differences were not correlated to the degree of convection. Discussion of these results and future extensions of the work are presented.

IC-P3-207: Decreased activation in the left medial parietal lobe in presymptomatic FAD mutation carriers in fMRI during an unrelated word pair memory task

2 and Lesion Explorer 3 WMH segmentation was performed, with VichowRobin perivascular spaces excluded. To appreciate the 3-dimensional anatomy of WMH, PV-WMH was defined as any hyperintensity touching the ventricles in 3D, the remaining discrete WMSH were defined as DWWMH. Hypointense components within PV-WMH and DW-WMH of cerebrospinal fluid intensity on T1-based segmentation were considered to represent cystic necrosis. Volumetrics were obtained. Hypointense lesion volumes were expressed as percentage of WMH. Results: Mean percentage of hypointensities were as follows: periventricular (AD 2.2%, NC 0.37%); deep white (AD 2.16%, NC 1.6%), with the PV between group difference approaching significance (p .07). Total PV-WMH and DW-WMH volumes was significantly correlated in NC (r .62, p .019) but not in AD (r .32, p .24). However, DW and PV hypointensities did not show correlation (NC: r -.05, p .87; AD: r .24, p .39). Conclusions: The higher percentage of implied cystic necrosis in the PV distribution, and the differences in DW and PV correlations in AD and NC, suggests a different underlying pathology occurring in the periventricular regions of AD patients. It is recommended that future studies examining WMH should include PV and DW delineations as well as an additional T1-based hypointense segmentation to account for these lesions.