scholarly journals Alternative Criteria of Voltage Stability Margin for the Purpose of Load Shedding

2021 ◽  
Vol 9 (10) ◽  
pp. 201-206
Author(s):  
Praveen Kumar
Keyword(s):  
Open Access ◽  
Stability Margin ◽  
Load Shedding ◽  
New Method ◽  
Voltage Instability ◽  
Major Threat ◽  
The Past ◽  
Voltage Stability Margin ◽  
Limit Power ◽  
Maximum Utilization

Abstract: Voltage instability takes on the form of a dramatic drop of transmission system voltages, which may lead to system disruption. During the past two decades it has become a major threat for the operation of many systems and, in the prevailing open access environment, it is a factor leading to limit power transfers. The objective of this paper is to present new method of under voltage protection with maximum utilization of system capabilities.

scholarly journals Decentralized Load Shedding Method Based on Voltage Stability Margin Index Using Synchrophasor Measurement Technology

Electronics ◽  
2018 ◽  
Vol 7 (11) ◽  
pp. 277 ◽  
Author(s):  
Yunhwan Lee ◽  
Hwachang Song
Keyword(s):  
Power Systems ◽  
Voltage Stability ◽  
Stability Margin ◽  
Load Shedding ◽  
Measurement Technology ◽  
Dynamic Simulations ◽  
Stability Margins ◽  
Voltage Instability ◽  
Voltage Stability Margin ◽  
Simulation Results

This study develops an analytical method for assessing the voltage stability margins of a decentralized load shedding scheme; it then examines the challenges related to the existing load shedding scheme. It also presents a practical application for implementing the proposed method, based on the synchrophasor measurement technology in modern power grid operations. By applying the concept of a continuously-computed voltage stability margin index to the configuration of the Thévenin equivalent system, the maximum transfer power could be used as an index to monitor the voltage instability phenomenon and thus determine the required load shedding amount. Thus, the calculated voltage stability margin might be a useful index for system operators in the critical decision-making process of load shedding. Dynamic simulations are performed on real Korean power systems as case studies. Simulation results, when comparing the existing and proposed methods, showed that there was a considerable reduction in the amount of load shedding in the voltage instability scenario. This indicates that the synchrophasor measurement technology has a considerable effect on the proposed load shedding method. The simulation results have validated the performance of the proposed method.

An Optimal Load Shedding Methodology for Radial Power Distribution Systems to Improve Static Voltage Stability Margin using Gravity Search Algorithm

2014 ◽  
Vol 68 (3) ◽  
Author(s):  
Aziah Khamis ◽  
H. Shareef ◽  
A. Mohamed ◽  
Erdal Bizkevelci
Keyword(s):  
Power Distribution ◽  
Distribution System ◽  
Distribution Systems ◽  
Voltage Stability ◽  
Search Algorithm ◽  
Gravitational Search Algorithm ◽  
Stability Margin ◽  
Maximum Amount ◽  
Load Shedding ◽  
Voltage Stability Margin

Voltage stability is one of the major concerns in operational and planning of modern power system. Many strategies have been implemented to avoid voltage collapse, which the load shedding considered as the last option. However, optimization is needed to estimate the minimum amount to shed so as to prevent voltage instability. In this paper, an effective method is presented for estimating the optimal amount of load to be shed in a distribution system based on the gravitational search algorithm (GSA). The voltage stability margin (VSM) of the system has been considered in the objective function. The optimization problem is formulated to maximize the VSM of the system and at the same time satisfying the operation and security constraints. The optimum solution depends on the predefined constraints such as the number of load buses available to shed and the maximum amount of load permitted to shed. Simulation result conducted on the IEEE 33 bus radial distribution system shows that the system voltage stability can be improved by optimally shedding the loads at critical system buses. The results also indicate that the numbers of load buses available for load shedding does not have a significant impact on voltage stability margin, but it is highly dependent on the maximum amount of load permitted to shed. 

scholarly journals Multiple-deme parallel genetic algorithm based on modular neural network for effective load shedding

2021 ◽  
Author(s):  
Ali Gholami-Rahimabadi ◽  
Hadi Razmi ◽  
Hasan Doagou-Mojarrad
Keyword(s):  
Neural Network ◽  
Genetic Algorithm ◽  
Voltage Stability ◽  
Stability Margin ◽  
Test System ◽  
Load Shedding ◽  
Parallel Genetic Algorithm ◽  
Detailed Model ◽  
Modular Neural Network ◽  
Voltage Stability Margin

Abstract One of the most effective corrective control strategies to prevent voltage collapse and instability is load shedding. In this paper, a multiple-deme parallel genetic algorithm (MDPGA) is used for a suitable design of load shedding. The load shedding algorithm is implemented when the voltage stability margin index of the power system is lower than a predefined value. In order to increase the computational speed, the voltage stability margin index is estimated by a modular neural network method in a fraction of a second. In addition, in order to use the exact values of the voltage stability margin index for neural network training, a simultaneous equilibrium tracing technique has been employed considering the detailed model of the components of the generating units such as the governor and the excitation system. In the proposed algorithm, the entire population is partitioned into several isolated subpopulations (demes) in which demes distributed in different processors and individuals may migrate occasionally from one subpopulation to another. The proposed technique has been tested on New England-39 bus test system and the obtained results indicate the efficiency of the proposed method.

scholarly journals Voltage Stability Indices: Formulation and Classification Perspectives

2019 ◽  
Vol 8 (12) ◽  
pp. 5777-5785
Keyword(s):  
Power Systems ◽  
Voltage Stability ◽  
Stability Margin ◽  
Stability Evaluation ◽  
Chronological Order ◽  
Real Time Control ◽  
Voltage Instability ◽  
Time Control ◽  
Voltage Stability Margin ◽  
Stability Indices

Voltage instability had been observed as the foremost cause of blackout incidents worldwide in last three decades. In order to deploy an appropriate countermeasure and enhance voltage stability margin, voltage stability predictor is of utmost importance. Therefore, much research had been focussed to propose voltage stability indices (VSIs) that can identify weak areas and overall condition of power systems. In this paper systematic review covering imperative aspects of formulation theory, expressions, critical values and applicability of VSIs has been presented in chronological order. A broad categorization of VSIs is also addressed. An inclusive review provides a strong foundation for further research in the perspective of voltage stability evaluation for real-time control applications.

Children’s Lives and Deaths in Merovingian Gaul

2020 ◽  
pp. 185-213
Author(s):  
Émilie Perez
Keyword(s):  
Social Identity ◽  
Age Groups ◽  
New Method ◽  
Recent Analysis ◽  
Age And Gender ◽  
The Past ◽  
And Gender ◽  
Grave Goods

The role of children in Merovingian society has long been downplayed, and the study of their graves and bones has long been neglected. However, during the past fifteen years, archaeologists have shown growing interest in the place of children in Merovingian society. Nonetheless, this research has not been without challenges linked to the nature of the biological and material remains. Recent analysis of 315 children’s graves from four Merovingian cemeteries in northern Gaul (sixth to seventh centuries) allows us to understand the modalities of burial ritual for children. A new method for classifying children into social age groups shows that the type, quality, quantity, and diversity of grave goods were directly correlated with the age of the deceased. They increased from the age of eight and particularly around the time of puberty. This study discusses the role of age and gender in the construction and expression of social identity during childhood in the Merovingian period.

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