A New Structure of Dynamic Voltage Restorer Based on Asymmetrical 􀄫-source Inverters to Compensate Voltage Disturbances in Power Distribution Networks

Author(s):  
Mahmoud Zadehbagheri ◽  
Rahim Ildarabadi ◽  
Majid Baghaei Nejad ◽  
Tole Sutikno

As a consequence of sensitive, diverse and complex loads in today's distribution networks, improving power quality in distribution systems has attracted great attention. Power quality issues involve voltage sags, transient interrupts and other distortions in sinusoidal waveforms. Enormous methods have been proposed for power quality modification. One of the methods by which power quality problems might be addressed is to apply power electronic devices in the form of custom power devices. One of such devices is Dynamic Voltage Restorer (DVR) which is connected in series to distribution networks. At the same time, through injection of voltage to the network it is able to control voltage amplitude and phase. It is adopted lend to compensate for voltage sags through injecting series and synchronous three phase voltage. Consisted of three single phase inverters and a DC bus, it can protect susceptible loads against various types of voltage sags as well as other disturbances in the power supply. Moreover, it is capable of generating and absorbing active and reactive power. Therefore, in this paper, different structures of  DVR have been investigated and eventually proposed a new structure for DVR based on Γ-Source asymmetric inverter. With the proposed structure, severe voltage sags can be retrieved 80- 90 percent. The simulation results that obtained by using MATLAB/Simulink indicate the properly functioning of proposed structure.

Author(s):  
Mahmoud Zadehbagheri ◽  
Rahim Ildarabadi ◽  
Majid Baghaei Nejad ◽  
Tole Sutikno

<p>Power distribution networks are considered the main link between power industry and consumers and they are exposed to public judgment and evaluation more than any other section. Thus, it is essential to study power quality in distribution section. On the other hand, power distribution networks have always been exposed to traditional factors such as  voltage sag, voltage swell, harmonics and capacitor switching which destruct sinusoidal waveforms and decrease power quality as well as network reliability. One of the methods by which power quality problems might be addressed is to apply power electronic devices in the form of custom power devices. One of such devices is Dynamic Voltage Restorer (DVR) which is connected in series to distribution networks. At the same time, through injection of voltage to the network it is able to control voltage amplitude and phase. It is  adopted lend to compensate for voltage sags through injecting series and synchronous three phase voltage. This paper reviews on the application of DVR for Voltage Compensation in recent years and gives sets of information for each control of the DVR in distribution networks.</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):  
Lakshmi Lakshmi Kumari ◽  
Uma Vani Uma Vani

<p>This paper presents the application of dynamic voltage restorers (DVR) on power distribution Systems for mitigation of voltage sags/swells at critical loads. DVR is one of the compensating types of custom power devices. The power quality is affected mainly due to the sensitive loads which results in voltage sag and voltage swells. It is necessary to investigate the suitable methods for mitigation of voltage sags. Sensitivity is the main cause of the above power quality problems and it cannot be eliminated completely as it has many other operating properties. So the next possible solution is to correct the problems caused by the sensitive equipments connected to the faulty loads. The occurrence of sag and swell varies with equipment, environment, process operations, desired control schemes etc. From the wide range of mitigation methods, the selected one has to be observed for the effect on the characteristics. These problems can be mitigated with voltage injection method using custom power device, Dynamic Voltage Restorer (DVR). In this paper we design a Dynamic Voltage Restorer (DVR) which is utilized for power quality improvement. The main power quality problems like voltage sag and swell are studied in this paper. The device used to phase out voltage sags and a swell in the distribution lines is the Dynamic Voltage Restorer (DVR). The Dynamic Voltage Restorer is a special type of power device used for providing consistent and reliable supply power to the load devices. Dynamic Voltage Restorer uses a vector control strategy for mitigating power quality problems by automatically detecting and injecting the voltage components through an injection transformer. Here comes the importance of soft computing techniques like PI controller. The system will be able to correct repeated occurrences of the power quality problems. </p>


In the present energy scenario, one of major problems is with Power quality. Power quality came to more relevant, focused, with the addition of suitable equipment, where its behavior is very much important to the power supply quality. Power quality issue is a phenomenon noted as a not usual standard current, frequency or voltage which may results in a failure of sophiscated devices. The main issue focuses at the power swell & sag. In the paper, authors present a novel methodology for the prevention of voltage sag & swell. To rectify this issue, customized power equipments are adopted. Among them, Dynamic Voltage Restorer (DVR), the best as well as right advanced customized power equipment used in power distribution networks. The advantages include reduced price, low size, and its good transient response to the interferences. This work explain the MATLAB results of a Dynamic Voltage Restorer (DVR) modeling and analysis. Here, conventional controller like PI type and GA Tuned PI controller are used for comparison. In the offered method, PI controller parameters using GA Tuned implemented is being replaced by the traditional PI controller in order to develop the performance of the plant. The aim of the controller is made faster than conventional technique based controller. By MATLAB simulation tool, the performance can be studied.


Author(s):  
A. Sathik Basha ◽  
M. Ramasamy

Increased utilization of nonlinear loads in the power distribution system with profound integration of renewable energy requires improved power quality control. This paper proposes a Reformed Second Order Generalized Integrated (R-SOGI) control scheme for enhancing the output of the Dynamic Voltage Restorer (DVR) for the objective of achieving the desired sinusoidal voltage wave shape at the common point of services and harmonic reduction. The DVR incorporates a Solar Photovoltaic (SPV) system using the Z-source Inverter (ZSI), providing the necessary active power to mitigate the voltage sag/swell and power demand. ZSI offers step-down as well as step-up abilities, it makes the converters to operate in the conditions of shoot-through. Therefore, the application of ZSI-based DVR topology seems very promising. The compensating reference voltage is generated by the R-SOGI algorithm, which offers superior output under conditions for grid voltage irregularities, including voltage sag/swell and unbalanced and distorted utility grid voltages. In comparison to DVR based on the VSI voltage inverter (VSI), the response from ZSI-DVR to a reduction of voltage distortions and harmonics is investigated. An experimental SPV ZSI-DVR prototype is developed in the laboratory to check the effectiveness of the controller and is tested under balanced and unbalanced supply and dynamic load conditions.


Author(s):  
Amarjeet Singh ◽  
Shivangee Shukla

The Wind generation system has potential application for the grid support that could be utilized in rural areas. However, continuous variation of wind speed results in severe power quality problems, especially in a standalone village network. In distributed generation, wind power system can cause sub harmonic and interharmonic components to appear in the spectrum of voltage and currents. These harmonics can cause flicker, overload, and interference, on the electronic equipments. This paper proposes Dynamic Voltage Restorer (DVR), which is the most efficient and effective modern custom power device used in power distribution networks. This could be used to improve the power quality in a rural load fed from a wind driven permanent magnet synchronous generator (PMSG). The reference voltage is tracked by voltage source converter using a switching band scheme. A method of extracting the phasor symmetrical components that contain both integer and non integer harmonics and complex Fourier transform relation is proposed. In this paper, it is demonstrated that this device can tightly regulate the voltage at the load terminal when load draws integer, non integer harmonic current and sag and swell in the source side.


Author(s):  
Patrick Taiwo Ogunboyo ◽  
Remy Tiako ◽  
Innocent E. Davidson

Dynamic Voltage Restorer (DVR) is a series connected power electronics based custom power device that is used to improve voltage disturbances in low voltage electrical power distribution network. Power quality requirement is one of the most important concerns for power system. The parts of the DVR is made up of voltage source inverter, injection/booster transformer, a harmonic filter, an energy storage device and a bypass switch. The DVR is used to inject three phase voltage in series and in synchronism with the network voltages in order to compensate voltage disturbances with a benefit of active /reactive power control. This paper presents a review of the researches on the dynamic voltage restorer application for power quality improvement in low voltage electrical power distribution networks. It describes power quality issues, principle of operation of DVR, basic components of DVR, DVRs control topologies in distribution network, DVR control strategies and compensation techniques.


2016 ◽  
Vol 818 ◽  
pp. 52-57 ◽  
Author(s):  
Faridullah Kakar ◽  
Abdullah Asuhaimi bin Mohd Zin ◽  
Mohd Hafiz bin Habibuddin

Voltage sag and harmonics are the most frequent power quality problems faced by industrial and commercial customers today. Situation has been aggravated by modern sensitive industrial equipments which introduce system harmonics due to their inherent V-I characteristics. In this paper, proportional integral (PI) control technique based dynamic voltage restorer (DVR) is implemented in power distribution system to suppress voltage sag and harmonics under linear, non-linear and induction motor load conditions. Real-time power distribution system and DVR test models are built in Matlab/Simulink software. Simulation results exhibit excellent PI control approach with effective performance yielding excellent voltage regulation.


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