scholarly journals Impact of uncertainties of lead times and expiration dates on the stability of inventory levels in a distribution system

2019 ◽  
Vol 52 (13) ◽  
pp. 1984-1989
Author(s):  
Berna Bou Farraa ◽  
Rosa Abbou ◽  
Jean Jacques Loiseau
Keyword(s):  
Distribution System ◽  
Lead Times ◽  
The Stability

Determining the Norton’s Equivalent Model of Distribution System with Distributed Generation (DG) for Stability Analysis

2019 ◽  
Vol 12 (2) ◽  
pp. 190-198
Author(s):  
Sunny Katyara ◽  
Lukasz Staszewski ◽  
Faheem Akhtar Chachar
Keyword(s):  
Distributed Generation ◽  
Normal Condition ◽  
Distribution System ◽  
Distribution Networks ◽  
Equivalent Model ◽  
Stability Factor ◽  
Matlab Simulation ◽  
The Stability ◽  
Stability Issues

Background: Since the distribution networks are passive until Distributed Generation (DG) is not being installed into them, the stability issues occur in the distribution system after the integration of DG. Methods: In order to assure the simplicity during the calculations, many approximations have been proposed for finding the system’s parameters i.e. Voltage, active and reactive powers and load angle, more efficiently and accurately. This research presents an algorithm for finding the Norton’s equivalent model of distribution system with DG, considering from receiving end. Norton’s model of distribution system can be determined either from its complete configuration or through an algorithm using system’s voltage and current profiles. The algorithm involves the determination of derivative of apparent power against the current (dS/dIL) of the system. Results: This work also verifies the accuracy of proposed algorithm according to the relative variations in the phase angle of system’s impedance. This research also considers the varying states of distribution system due to switching in and out of DG and therefore Norton’s model needs to be updated accordingly. Conclusion: The efficacy of the proposed algorithm is verified through MATLAB simulation results under two scenarios, (i) normal condition and (ii) faulty condition. During normal condition, the stability factor near to 1 and change in dS/dIL was near to 0 while during fault condition, the stability factor was higher than 1 and the value of dS/dIL was away from 0.

scholarly journals An Approach to Estimating Water Quality Changes in Water Distribution Systems Using Fault Tree Analysis

Resources ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 162 ◽  
Author(s):  
Barbara Tchórzewska-Cieślak ◽  
Katarzyna Pietrucha-Urbanik ◽  
Dorota Papciak
Keyword(s):  
Water Supply ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Fault Tree ◽  
Water Distribution Systems ◽  
Fault Tree Analysis ◽  
Quality Changes ◽  
The Stability ◽  
Water Treatment Station

Given that a consequence of a lack of stability of the water in a distribution system is increased susceptibility to secondary contamination and, hence, a threat to consumer health, in the work detailed here we assessed the risk of such a system experiencing quality changes relating to the biological and chemical stability of water intended for drinking. Utilizing real operational data from a water treatment station, the presented analysis of the stability was performed based on the fault tree method. If they are to protect their critical-status water supply infrastructure, water supply companies should redouble their efforts to distribute stable water free of potentially corrosive properties. To that end, suggestions are made on the safeguarding of water distribution systems, with a view to ensuring the safety of operation and the long-term durability of pipes.

Analysis and Stability Enhancement of DG Sourced Power System with Modified AVR and PSS

2013 ◽  
Vol 768 ◽  
pp. 313-316
Author(s):  
P. Sivakumar ◽  
C. Birindha
Keyword(s):  
Power System ◽  
Distribution System ◽  
Transient Stability ◽  
Probabilistic Approach ◽  
Small Signal Stability ◽  
Signal Stability ◽  
The Stability ◽  
System Stabilizer ◽  
Stability Issues ◽  
Stability Enhancement

Distribution system is facing stability issues with integration of distributed generators and controllers. This proposed method presents the stability of renewable energy based distribution system with varying energy source considering intermittent nature of wind and solar energy using probabilistic approach. The system is supplied by conventional and distributed generating sources like PV and wind. Monte Carlo approach is used for predicting the wind and solar power uncertainties. Proposed work explains both small signal stability and transient stability enhancement of DG sourced power system with power system stabilizer and automatic voltage regulator .It is carried out in is 4 machine 10 bus system. The initial simulation has been carried out using MATLAB/SIMULINK.

Study on Stability and Reactive Power Optimization of Active Distribution Network Based on Bifurcation Theory

2015 ◽  
Vol 734 ◽  
pp. 701-706
Author(s):  
Xian Bin Dai
Keyword(s):  
Power Distribution ◽  
Distribution System ◽  
Nonlinear Dynamic ◽  
Bifurcation Theory ◽  
Reactive Power ◽  
Distribution Network ◽  
Nonlinear Dynamic System ◽  
Reactive Power Optimization ◽  
Power Distribution Network ◽  
The Stability

as the basic method used to analyze the stability of nonlinear dynamic system, it is able to more deeply discuss the stability problems of power system in the vicinity of a critical point in comparison with traditional analysis method. Active power distribution network is a complicated nonlinear dynamic system. The change of voltage stability is the process to convert from stable status to bifurcation in essence. Taking 10-node active distribution system as an example, the author studies the influence of reactive power optimization on voltage stability based on bifurcation theory. The author explains the reactive optimization algorithm based on numerical simulation, namely, it is the decision - making algorithm in order to realize multiple purposes of having minimum power network loss, largest reactive power margin with stable operation of power distribution network and minimum voltage floating in system fluctuation, which is proved to be effective in elevating power distribution system stability, reducing power loss and improving voltage quality.

Numerical Study of Transient Flow and the Influence of Height and Viscosity in a Cyclonic Chamber in a Distribution System

2017 ◽  
Author(s):  
Carolina C. Rodrigues ◽  
Henrique K. Eidt ◽  
Rafael Dunaiski ◽  
César Y. Ofuchi ◽  
Flávio Neves ◽  
...  
Keyword(s):  
Distribution System ◽  
Transient Flow ◽  
Separation Efficiency ◽  
Numerical Study ◽  
Petroleum Industry ◽  
Wire Mesh ◽  
Intermittent Flow ◽  
Transient Effects ◽  
Centrifugal Pumps ◽  
The Stability

In the petroleum industry, during the production and transportation of oil, multiphase flow occurs, due to the usual mixture of the crude oil, water and gas. This type of flow can be simplified, for study purposes, as a two-phase one, in which the gas is one phase, and a mixture of oil and water is the other. Separation of gaseous and liquid phases at the wellhead level is done by a separator and has innumerous advantages, including avoiding or at least reducing typical problems of multiphase flows such as intermittent flow, severe slugging and hydrates deposition. Another advantage is to increase the efficiency of the submersible centrifugal pumps or other artificial lift process used. A recurrent problem found in exploration and production of oil and gas is the range of the fluid viscosities encountered during exploration and extraction of petroleum, which can greatly vary with the temperature or the composition of the oil being extracted. Thus, it is necessary to understand how this parameter affects the performance of the equipment used. In addition, installation and maintenance of separators are hampered by the large size of this type of equipment. Therefore, a prior distribution system is here proposed, aiming to distribute the flow in more than one branch, in order to decrease the general size of the separation equipment needed, while maintaining the flow rate and separation efficiency. This distribution system has a cyclonic chamber, in which the flow enters through two nozzles tangentially oriented with the wall of the chamber, which performs a pre-separation due to the centrifugal field, and divides the flow into four outlets. This work presents a numerical study on the height influence of the cyclonic chamber in a distribution system. The transient beginning of the flow is analyzed, with the stability of the film being study. This work is focused on the behavior of the liquid phase in this proposed distribution system, so that only single-phase liquid flow at the inlet of the distribution system is considered. A validation was done through comparison with experimental data obtained in a test rig, in which was used one wire mesh sensor with 12 wires in order to evaluate the thickness of the liquid film over time. In addition, different heights and viscosities are studied in order to evaluate their influence on the flow. The parameters investigated are the film thickness, velocity and turbulence kinetic energy fields and flow rates at the outlets, focusing on the stability of the film and the transient effects associated with the beginning of the flow. In order to perform this study, the commercial software ANSYS-CFX 15.0 was used, with a hybrid mesh, for four different heights and two inlet velocities.

scholarly journals The Impact of the Handling Unit on Logistics Costs: The Case of a Portuguese Food Retail Supply Chain

2020 ◽  
Vol 5 (5) ◽  
pp. 835-850
Author(s):  
Ana Luísa Ferreira Andrade Ramos ◽  
José António Vasconcelos Ferreira ◽  
Sara Rego da Costa
Keyword(s):  
Supply Chain ◽  
Distribution System ◽  
Cost Model ◽  
Lead Times ◽  
Food Retail ◽  
Distribution Centre ◽  
Quantitative Results ◽  
High Level ◽  
High Degree ◽  
The Impact

In the food retail industry, the agility and responsiveness of the supply chain are crucial because demand is volatile and short lead times are mandatory. The logistics performance is of critical importance to provide a high level of efficiency in operations and a high degree of customer satisfaction. The Handling Unit, or the minimum quantity to send to retail stores (the ship-pack), is a factor of considerable influence on logistics efficiency and costs. In this work, it was developed a simple analytical cost model for a Portuguese food retail two-tier distribution system (distribution centre and store) to support the evaluation of the conversion of the handling unit to half-pallet. The results of the model, considering a pilot study with three scenarios, suggest an economic gain of approximately 75% (comparatively to the current situation) in logistics costs. These quantitative results were decisive to guide decision-makers.

scholarly journals System-Wide Enhancement Of Distribution System Voltage Stability Operations

2021 ◽  
Author(s):  
Alexander Hamlyn
Keyword(s):  
Distribution System ◽  
Voltage Stability ◽  
Reactive Power ◽  
Extensive Study ◽  
Voltage Stability Enhancement ◽  
Corrective Actions ◽  
Available Technology ◽  
The Stability ◽  
Stability Issues ◽  
Stability Enhancement

To take on the challenge for improving the distribution system voltage stability, this thesis research carried out an extensive study of the stability issues and available technology dealing with the stability problems. Load shedding, Load reduction through transformer tap changing, reactive power compensation, and DG control are investigated in detail. The new strategies proposed, and formulations presented, in this thesis research, are designed for carrying out the corrective actions against voltage instability with a great degree of feasability to achieve optimal operations. A new concept of composite power was developed in this thesis research, for prediction of the trend of voltage stability, and a novel prediction of voltage stability and consequently determination of corrective actions was formulated. A detailed hardware/software based development of the algorithm and strategy for voltage stability enhancement was presented. A detailed set of case studies for verification of the voltage stability enhancement was developed.

scholarly journals A Multi-Market-Driven Approach to Energy Scheduling of Smart Microgrids in Distribution Networks

2019 ◽  
Vol 11 (2) ◽  
pp. 301 ◽  
Author(s):  
Jingpeng Yue ◽  
Zhijian Hu ◽  
Amjad Anvari-Moghaddam ◽  
Josep M. Guerrero
Keyword(s):  
Distribution System ◽  
Stackelberg Game ◽  
Distribution Networks ◽  
Test System ◽  
Market Mechanism ◽  
Distribution Grid ◽  
Wholesale Market ◽  
Service Market ◽  
System Operator ◽  
The Stability

In order to coordinate the economic desire of microgrid (MG) owners and the stability operation requirement of the distribution system operator (DSO), a multi-market participation framework is proposed to stimulate the energy transaction potential of MGs through distributed and centralized ways. Firstly, an MG equipped with storage can contribute to the stability improvement at special nodes of the distribution grid where the uncertain factors (such as intermittent renewable sources and electric vehicles) exist. The DSO is thus interested in encouraging specified MGs to provide voltage stability services by creating a distribution grid service market (DGSM), where the dynamic production-price auction is used to capture the competition of the distributed MGs. Moreover, an aggregator, serving as a broker and controller for MGs, is considered to participate in the day-ahead wholesale market. A Stackelberg game is modeled accordingly to solve the price and quantity package allocation between aggregator and MGs. Finally, the modified IEEE-33 bus distribution test system is used to demonstrate the applicability and effectiveness of the proposed multi-market mechanism. The results under this framework improve both MGs and utility.

The Analysis of Zero Inventory Drift Variants Based on Simple and General Order-Up-To Policies

2010 ◽  
Vol 1 (3) ◽  
pp. 37-52
Author(s):  
Jianing He ◽  
Haibo Wang
Keyword(s):  
Analysis Of Variance ◽  
Lead Time ◽  
Minimum Mean Square Error ◽  
Lead Times ◽  
Control Engineering ◽  
Final Value ◽  
Demand Pattern ◽  
General Order ◽  
The Stability ◽  
Zero Inventory

In this paper, simple and general Order-Up-To (OUT) models with Minimum Mean Square Error (MMSE) forecast for the AR(1) demand pattern are introduced in the control engineering perspective. Important insights about lead-time misidentification are derived from the analysis of variance discrepancy. By applying the Final Value Theorem (FVI), a final value offset (i.e., inventory drift) is proved to exist and can be measured even though the actual lead-time is known. In this regard, to eliminate the inherent offset and keep the system variances acceptable, two kinds of zero inventory drift variants based on the general OUT model are presented. The analysis of variance amplification suggests lead-times should always be estimated conservatively in variant models. The stability conditions for zero inventory drift variants are evaluated in succession and some valuable attributes of the new variants are illustrated via spreadsheet simulation under the assumption that lead-time misidentification is inevitable.

Environmental Study on the Behavior of Water Drops with Circular Resin Insulator Material under DC Electric Field Stress

2014 ◽  
Vol 979 ◽  
pp. 111-114
Author(s):  
Soukvilay Phimmasene ◽  
Kittipong Tonmitra ◽  
Apirat Siritaratiwat ◽  
Arkom Kaewrawang
Keyword(s):  
Distribution System ◽  
Water Drop ◽  
Environmental Study ◽  
Single Drop ◽  
Electrical Field ◽  
High Voltage Direct Current ◽  
Dc Electric Field ◽  
Water Drops ◽  
The Stability ◽  
Lower Voltage

The influence of damages on the insulator’s surface in the distribution system is investigated in this paper. The circular resin is used as the specimen under high voltage direct current (HVDC) between the electrodes with diameter of 2 mm and distance between both electrodes are 35 mm. There are three cases in the experiment and it was tested in environmental condition under dry surface, single droplet and double droplets. The HVDC had been applied to the electrodes, the level of applied were 5, 10, 15, 20, 25, 30 and 35 kV. The results show that the arc occurs rapidly in the case of single and double drops with compared to dry surface. The movements of the water drop of the single and doubles are pretty similar, but the arc occurs quickly in the double drop in comparison with single drop owing to double drops stretch to each other. The double drops take a lower voltage on stretching, whereas the single drop takes higher because the double drops have much more densities than single drop. Besides, the double drops act as a bridge allow the electrical field generated from both electrodes pulled them resulting in arcing easily. In conclusion, the droplets on the surfaces cause the leakage current and it has an effect on the stability of the distribution system.

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