An Optimum UPQC with Minimum VA Requirement and Mitigation of Unbalanced Voltage Sag

Author(s):  
Y. Y. Kolhatkar ◽  
S. P. Das

The paper deals with an optimized Unified Power Quality Conditioner (UPQC), which aims at the integration of series active and shunt active power filters with minimum VA loading of the UPQC. The series active filter is a Dynamic Voltage Restorer (DVR), which is operated in twofold functioning mode. During the unbalanced voltage sag, the DVR compensates the unbalance in the voltage sag. It also regulates the voltage at the load end with minimum VA loading of the overall UPQC by optimum angle voltage injection. Validity of the proposed scheme is proved through extensive simulation results.

2015 ◽  
Vol 2 (4) ◽  
pp. 1-6
Author(s):  
K. Venkateswarlu ◽  
◽  
B. Ashwin Kumar ◽  
N. Srinivas ◽  
V. Mallikarjuna Rao ◽  
...  

The aim of this paper is to present a new simplified topology for a Dynamic Voltage Restorer (DVR) which has ability to mitigate single phase outage also. The proposed DVR has a multi-winding transformer, a direct converter and a series transformer for each phase. The multi winding transformer is connected between the direct converter and the grid. Only three bi-directional controlled switches are employed per phase. The direct converter is used to synthesis the required compensating voltage and the series transformer is used to add the compensating voltage in grid. The DVR can compensate balanced voltage sag, balanced swell, unbalanced swell and single phase outage by taking power from the grid. For compensating the voltage sag or outage in any one phase, the other two phase voltages are added using the multi winding transformer. The added voltage is pules-width modulated (PWM) using controlled switches to compensate the sag. Swell is compensated by taking power from the same phase. The simulation results confirm that the proposed topology can mitigate balanced sag of 50%, balanced swell of 100%, unbalanced swell of 100% and single phase outage.


Author(s):  
Deshpande V. Chinmay ◽  
Deshpande V. Chaitanya

<p><span lang="EN-US">DVR is power electronic based device used for mitigation of voltage sag problem. In this paper, various inverter topologies such as Voltage source inverter, Z source inverter and Embedded Z source inverter are used and compared for operation of DVR. Here dual p-q theory is implemented as control technique which have excellent transient response and speed. Different inverter configurations are implemented for DVR and its simulation results are presented and compared. It has been observed that Embedded EZ source inverter topology is found to be effective. The Embedded EZ source inverter topology and its hardware results are presented and compared.</span></p>


Author(s):  
S. Abdul Rahman ◽  
Estifanos Dagnew

<p class="Text"><span>The aim of this paper is to present a modulation technique to achieve highest voltage sag compensation using direct converter based dynamic voltage restorer (DVR). The DVR topology proposed in this paper, has a direct converter and a series transformer. The direct converter is fabricated using only two bi-directional switches. The DVR is designed to compensate the sag in a phase by taking power from the same phase. The direct converter is connected between the series transformer and the line in which sag compensation is to be achieved. Conventionally, the PWM pulses for the direct converters are produced by comparing the error signal with the carrier signal. The error signal is obtained by comparing the amplitude of voltage in the line with the amplitude of the reference voltage. If the amplitude of the carrier signal is kept constant and the actual amplitude of error signal is used for PWM generation, it is possible to achieve only 22% of voltage sag compensation. But if the error signal amplitude is modulated according to the amplitude of existing voltage sag in the line, 52% of the voltage sag can be compensated with the THD less than 5%. Simulation results are presented for validating the analysis. </span></p>


Sign in / Sign up

Export Citation Format

Share Document