Voltage Sag Evaluation Method of a Real Distribution System Based on a Connection Number Model

2013 ◽  
Vol 341-342 ◽  
pp. 1363-1366
Author(s):  
Lang Bai ◽  
Le Yu

The evaluation results of power system are greatly influenced by the reliability parameters and uncertainty of system components. The connection number assessment model and an approach have been presented to assess the occurrence frequency due to voltage sags. The proposed method had been applied to a real distribution system. Compared with the interval number method, the simulation results have shown that this method is simple and flexible.

2012 ◽  
Vol 605-607 ◽  
pp. 819-823
Author(s):  
Li Pin Chen ◽  
Xian Yong Xiao ◽  
Ying Wang ◽  
Jian Jiao

When faults happen to the power system components, the duration of voltage sags is determined by the cooperation of protection system. Many literatures have been done in analyzing the factors which influence the magnitude of voltage sags, but the impact of protection cooperation on sag duration is not considered by existing studies. In order to estimate the duration of voltage sags more precisely, the novelty of the proposed approach is in probabilistic modeling of the cooperation of the protection system using the concept of Markov state space, then voltage sag frequency and sensitive equipment trips considering protection cooperation can be estimated by utilizing the configuration and setting value of the protection system. The proposed method was applied to the IEEE 57-bus test system, and the simulation results show that the proposed method is practical, simple and adaptive.


2019 ◽  
Vol 15 (2) ◽  
pp. 138-144
Author(s):  
Adnan Diwan ◽  
Khalid Abdulhasan

voltage sags represent the greatest threat to the sensitive loads of industrial consumers, the microprocessor based-loads, and any electrical sensitive components. In this paper, a special topology is proposed to mitigate deep and long duration sags by using a modified AC to AC boost converter with a new control method. A boost converter is redesigned with a single switch to produces an output voltage that is linearly proportional to the duty cycle of the switch. On the other hand, the proposed control system is based on introducing a mathematical model that relates the missing voltage to the duty cycle of the boost converter switch. The simulation results along with the system analysis are presented to confirm the effectiveness and feasibility of the proposed circuit.


Author(s):  
Khánh Bạch Quốc

Abstract - One of popular and effective solutions to voltage sag mitigation is the use of custom power devices (CPD) like dynamic voltage restorers (DVR). On the other hand, fault current limiter FCL) also has impacts on voltage sags caused by faults. This paper introduces a new combination between DVR and solid-state fault current limiter (SSFCL) that can further improve global performance of voltage sags due to faults in distribution system. The location of DVR-SSFCL combination is optimally selected basing on minimizing a global index - SARFIX. In optimizing DVR-SSFCL combination’s placement, various cases of parameters relating with its ratings are considered and discussed. The paper uses IEEE’s 33-bus distribution system for modeling voltage sag due to faults and DVR-SSFCL combination’s effectiveness on global voltage sag mitigation.


Author(s):  
D.R. PATIL ◽  
KOMAL K. MADHALE

This paper presents the design of a prototype distribution static compensator (DSTATCOM) for voltage sag mitigation in an unbalanced distribution system. The D-STATCOM is intended to replace the widely used static Var compensator (SVC). The model is based on the Voltage Source Converter (VSC) principle. A new PWM based control scheme has been implemented to control the electronic valves in two level of VSC. The D-STATCOM injects a current into the system to mitigate the voltage sags. In this work, the 6-pulse D-STATCOM configuration with IGBT has been designed using MATLAB SIMULINK. Accordingly, simulations are first carried out to illustrate the use of D-STATCOM in mitigating voltage sag in a distribution system. Simulation results prove that the D-STATCOM is capable of mitigating voltage sag as well as improving power quality of a system.


Author(s):  
Arup Kumar Goswami ◽  
Chandra Prakash Gupta ◽  
Girish Kumar Singh

Voltage sag can cause considerable financial damage in an industry containing sensitive equipment. Many solutions exist to minimize financial losses due to voltage sag, varying from modification within the process itself to restructuring the supplying grid. In many cases the only possibility to minimize the financial losses is to install mitigation devices between the grid and the sensitive process such as power electronics devices Uninterruptible Power Supply (UPS). However, protecting the entire process by a dynamic or static UPS often turns out to be too expensive. This paper presents the minimization of financial losses due to voltage sag produced by balanced and unbalanced short circuit that occur at distribution system bus and along the transmission line using system impedance matrix (Z Bus) which incorporates D-STATCOM. The overall financial losses due to voltage sag could significantly change depending on the location of D-STATCOM used. In order to have an assessment of financial losses in real distribution systems, the classical static fault calculation should be amended to incorporate the effect of installation of these devices on financial losses. The cost-benefit analyses of inducting D-STATCOM for mitigating the effects of voltage sags have also been performed.Case studies based on a real Indian distribution system are used to illustrate the modeling method and the effectiveness of these devices in voltage sag mitigation.


DYNA ◽  
2015 ◽  
Vol 82 (192) ◽  
pp. 26-36
Author(s):  
Herbert Enrique Rojas-Cubides ◽  
Audrey Soley Cruz-Bernal ◽  
Harvey David Rojas-Cubides

<p class="Abstract"><span lang="EN-US">Voltage sags are the most common power quality disturbances in electrical facilities. It may cause malfunction in sensitive equipment and process interruption. The distribution static compensator (DSTATCOM) is a device that can compensate voltage sags by injecting reactive power into distribution system. This paper shows the influence on voltage sags characteristics by the presence of twelve-pulse DSTATCOM in the modified IEEE-13 distribution system. The analysis is performed by means of a random generation of disturbances using a MATLAB routine to identify the critical buses of the test system. Further, the DSTATCOM model taking advantage of the available elements from ATP/EMTP software is described. Simulations show that when DSTATCOM is placed directly to affected bus it is possible to obtain a complete mitigation of the voltage sag. Finally, the relation between the reactive power injected by DSTATCOM, the type of voltage sag and the location of affected bus is considered.</span></p>


2012 ◽  
Vol 622-623 ◽  
pp. 1830-1834 ◽  
Author(s):  
Mojtaba Hakimzadeh ◽  
Reza Sedaghati

Power quality has become an increasingly important topic in the performance of many industrial applications. One of the major issues in improving power quality in distribution networks is the mitigation of voltage sags. Voltage sag can be mitigated by voltage and power injections into the distribution system using Dynamic Voltage Restorer (DVR). The DVR is a powerful controller that is commonly used for voltage sags mitigation at the point of connection. This paper describes of modeling and analysis of DVR. Different types of faults are applied for DVR in distribution network and the responses of the system for these disturbances are examined. Simulation results obtained in PSCAD/EMTDC also prove that the DVR can mitigate voltage sag and protect bus bar voltage from various types of faults.


Author(s):  
Soe Soe Ei Aung ◽  
May Phone Thit

Electrical ac power systems consist of generation systems, transmission and distribution networks. The large three phase industrial loads at various distribution and transmission voltages as well as single-phase residential and commercial loads are supplied by the networks. Nowadays, the power quality such as voltage sags/swell, transient interrupts and harmonic distortions in sinusoidal waveforms are concerned with most of the electrical loads. The power quality problems such as voltage sags, swells and harmonics are caused by the widespread using of power electronics devices in power system. In this paper, electrical voltage sags/swells of power quality problems are considered because this problem is one of the most severe disturbances to the industrial equipment of distribution system. Thus, mitigation of these voltages in distribution system is necessary. So, series connected power electronics based device such as Dynamic Voltage Restorer (DVR) is chosen to compensate these voltage for mitigating quickly the voltage sag/swell in the system and restoring the load voltage to the nominal value. For case study, Myaungtagar industrial zone is chosen due to furnaces and large motor drives that cause the common problems such as voltage sag/swell in this system. In this paper, performance analysis of voltage sag/swell compensation of power distribution system with Dynamic Voltage Restorer (DVR) under various fault conditions is carried out. The proposed configuration model uses MATLAB/SIMULINK and the performance of voltage compensation and restoration of load voltage to the nominal value with DVR under various fault conditions is verified by the simulation results.


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