Performance Evaluation and Quality Analysis of Line and Node Based Voltage Stability Indices for the Determination of the Voltage Instability Point

2019 ◽  
pp. 367-376
Author(s):  
Pradeep Singh ◽  
Jyotsna Singh ◽  
Rajive Tiwari
Keyword(s):  
Performance Evaluation ◽  
Voltage Stability ◽  
Quality Analysis ◽  
Voltage Instability ◽  
Instability Point ◽  
Stability Indices

scholarly journals POWER SYSTEM CONTINGENCY RANKING BASED ON SHORT-TERM VOLTAGE STABILITY INDICES

2019 ◽  
Vol 49 (4) ◽  
pp. 225-232
Author(s):  
Jaime Dwaigth Pinzon Casallas ◽  
D. G. Colomé
Keyword(s):  
Dynamic Response ◽  
Power System ◽  
New England ◽  
Voltage Stability ◽  
Short Term ◽  
Voltage Instability ◽  
Contingency Ranking ◽  
Dynamic Voltage ◽  
Stability Indices

This paper presents a novel methodology to identify critical contingencies that produce short-term voltage stability problems (STVS). The proposed methodology classifies the state of the pow-er system for each contingency, assessing the voltage stability of the post-contingency dynamic response from the calculation of the maximal Lyapunov expo-nent (MLE) and dynamic voltage indices at each bus and the whole system. In order to determine the crit-ical contingencies, the values of the indices and the results of the classification of the post-contingency state are statistically analysed. The methodology is tested in the New England 39-bus system, obtaining satisfactory results in relation to the identification not only of the most critical contingencies but also of vulnerable buses to voltage instability. New contri-butions of this work are the contingency classifica-tion methodology, the algorithm for calculating dy-namic indices and the method of classification of the operating state as a function of the STVS problem magnitude.

A Novel Load Shedding Scheme for Voltage Stability

2016 ◽  
Vol 17 (6) ◽  
pp. 649-661 ◽  
Author(s):  
Sunil S. Damodhar ◽  
S. Krishna
Keyword(s):  
Voltage Stability ◽  
Load Shedding ◽  
Short Term ◽  
Voltage Instability ◽  
Local Measurements ◽  
Bus Voltage ◽  
Fast Acting ◽  
Multiple Buses ◽  
Large Disturbance

Abstract Undervoltage load shedding serves to maintain voltage stability when a majority of loads are fast acting. An undervoltage load shedding scheme should address two tasks: the detection of voltage instability following a large disturbance and the determination of the amount of load to be shed. Additionally, in case of short-term voltage instability, the scheme should be fast. This paper proposes a method to predict voltage instability arising due to a large disturbance. The amount of load to be shed to maintain voltage stability is then determined from the Thevenin equivalent of the network as seen from the local bus. The proposed method uses local measurements of bus voltage and power, and does not require knowledge of the network. The method is validated by simulation of three test systems subjected to a large disturbance. The proposed scheme is fairly accurate in estimating the minimum amount of load to be shed to maintain stability. The method is also successful in maintaining stability in cases where voltage collapse is detected at multiple buses.

A Review of Voltage Stability Assessment Techniques with an Improved Voltage Stability Indicator

2015 ◽  
Vol 16 (2) ◽  
pp. 107-115 ◽  
Author(s):  
Mir Sayed Shah Danish ◽  
Atsushi Yona ◽  
Tomonobu Senjyu
Keyword(s):  
Power System ◽  
Continuous Monitoring ◽  
Voltage Stability ◽  
Stability Assessment ◽  
Voltage Instability ◽  
Indicator Approach ◽  
Assessment Techniques ◽  
Power System Performance ◽  
Stability Indices ◽  
Broad Overview

Abstract A blackout can take place in entire power system or a part of the system due to extreme voltage instability (voltage collapse) that can appear abruptly. Instability prediction and continuous monitoring of the power system performance is, therefore, known exigent. This paper is conducted with a broad overview of the voltage stability indices, which are previously studied in the literature, and have the same foundation during their formulation. Afterward, an improved voltage stability indicator is introduced as a result of the multi-criteria integration and enhancement of the original indices by employing linear algebra methods. It is found that the proposed algorithm can overcome on the probable limitations from calculating point view. Then comparative analysis of the indices is presented in order to reach a unique consensus about the typical techniques of modal analysis (sensitivity, eigenvalue, right eigenvectors, and bus participation factor) as a precise algorithm. Finally, the IEEE 14-bus, and 30-bus test systems are selected to verify the algorithm, and compare the performance of the improved indicator approach with the existing indices.

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.

Selective Determination of Entecavir in the Presence of Its Oxidative Degradate by Spectrophotometric and Chromatographic Methods

2021 ◽  
Author(s):  
Heba M El-Sayed ◽  
Laila E Abdel Fattah ◽  
Hisham E Abdellatef ◽  
Maha A Hegazy ◽  
Mai M Abd El-Aziz
Keyword(s):  
High Selectivity ◽  
Oxidative Degradation ◽  
Hplc Method ◽  
Peak Amplitude ◽  
Quality Analysis ◽  
Official Method ◽  
Selective Determination ◽  
Significant Difference ◽  
Development And Validation

Abstract Background Entecavir (ENT) is an antiretroviral agent prescribed for treatment of HBV and HIV. Objective Development and validation of three simple, sensitive, selective, and precise methods for determination of ENT in presence of its oxidative degradation product (ENT deg.). Methods The first method was based on second derivative (D2) spectrophotometry through measuring the peak amplitude of D2 spectra at 293.6 nm. The second one is mean centering of the ratio spectra (MCR), which allowed measuring the peak amplitude at 280.0 nm. While the third method was HPLC; where ENT was separated from ENT deg. using Zobrax C18column and methanol: water (30:70, v/v), pH 3 as a mobile phase. The three developed methods were validated according to ICH guidelines. Results Linearity range of ENT was 5.00–50.00 μg/mL for both D2and MCR. However, higher sensitivity was achieved using HPLC (1.00–50.00 μg/mL). Accuracy of ENT were 100.60%±0.547, 101.55%±1.2071 and 100.61%±1.207 for D2, MCR and HPLC methods, respectively, and precision was within 1.280. Conclusions The developed methods were successfully applied for the determination of ENT in Tecavir® tablets without interference from ENT deg. They showed no significant difference compared with the official method as well as they could be applied in the quality analysis of ENT with high selectivity, accuracy, and precision. Highlights ENT was quantified using two spectrophotometric (D2 and MCR) methods and an HPLC method in presence of ENT deg. The proposed methods were applied to analysis of ENT tablets with high selectivity, sensitivity, and accuracy.

Analysis and determination of a seasonal performance evaluation for air source heat pumps

2021 ◽  
Vol 43 ◽  
pp. 102574
Author(s):  
Zixu Yang ◽  
Hansong Xiao ◽  
Wenxing Shi ◽  
Mingsheng Zhang ◽  
Baolong Wang
Keyword(s):  
Performance Evaluation ◽  
Heat Pumps ◽  
Seasonal Performance
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