Power Quality Improvement in Distribution System Using Dynamic Voltage Restorer

Author(s):  
Tesfahun Molla

With the advancement of technology, the dependency on the electrical energy has been increased greatly. Computer and telecommunication networks, railway network banking, post offices, and life support systems are a few applications that cannot function without electricity. At the same time, these applications demand qualitative energy. However, the quality of power supplied is affected by various internal and external factors of the power system. Harmonics, voltage, and frequency variations deteriorate the performance of the system. Voltage sag/dip is the most frequent problem and there are many methods to overcome this problem. The use of FACT devices is an efficient one. This chapter discusses an overview of the FACT device known as dynamic voltage restorer (DVR) in mitigating voltage sag. The strategy to control this device is also presented. The proposed control strategies are simulated in MATLAB SIMULINK environment and analyzed. The method is utilized and discussed briefly.

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.


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.


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.


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