A Control Method for Two Types of Three-Phase Transformerless Unified Power Quality Conditioner

Author(s):  
Fujian Li ◽  
Guochun Xiao ◽  
Fangzhou Zhao ◽  
Shuai Zhang ◽  
Baojin Liu
Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2927 ◽  
Author(s):  
Desmon Petrus Simatupang ◽  
Jaeho Choi

This paper proposes a multi-functional Photovoltaic (PV) inverter based on the Unified Power Quality Conditioner (UPQC) configuration. Power quality improvement is a difficult issue to solve for isolated areas or islands connected to the mainland through long submarine cables. In the proposed system, the line voltage is compensated for by the series inverter while the shunt inverter delivers the PV generating power to the grid. Depending on the technical conditions of power quality and system environment, it has five different operating modes. Especially during poor power quality conditions, the sensitive load is separated from the normal load to provide a different power quality level by using the microgrid conception. In this paper, the control method and the power flow for each mode are described, and the operational performance is verified through a PSiM simulation so that it can be applied to the power quality improvement of weak grid power systems such as in isolated areas or on islands connected to the mainland by long submarine cables.


Author(s):  
Madhusmita Patro ◽  
Kanhu Charan Bhuyan

<p>Power quality has become an important factor in power systems, for consumer and household appliances. The main causes of poor power quality are harmonic currents, poor power factor, supply voltage variations etc. A technique of achieving both active current distortion compensation, power factor correction and also mitigating the supply voltage variations at load side is compensated by unique device UPQC presented in this thesis. This concept presents a multi loop based controller to compensate power quality problems through a three phase four wire unified power quality conditioner (UPQC) under unbalanced and distorted load conditions. Here the UPQC is constituted of two voltage source converters (VSC) connected via power link. The series compensator is connected to the line in series and injects the voltage and thus compensates for voltage issues; whereas the shunt compensator injects current thus compensating for current issues, and is connected in shunt to the line. The voltage injection to the line uses an injecting transformer. The injection transformer is later replaced with injection capacitors, thus eliminating the drawback of conventional UPQC. In this way a good power quality is maintained.</p>


Author(s):  
Madhusmita Patro ◽  
Kanhu Charan Bhuyan

<p>Power quality has become an important factor in power systems, for consumer and household appliances. The main causes of poor power quality are har ue of achieving active current distortion compensation, power factor monic currents, poor power factor, supply voltage variations etc. A techniq correction and also mitigating the supply voltage variations at load side is compensated by unique device UPQC presented in this thesis. This concept presents a multi loop based controller to compensate power quality problems through a three phase four wire Unified Power Quality Conditioner (UPQC) under unbalanced and distorted load conditions. Here the UPQC is constituted of two Voltage Source Converters (VSC) connected via power link. The series compensator is connected to the line in series and injects the voltage and thus compensates for voltage issues; whereas the shunt compensator injects current thus compensating for current issues, and is connected in shunt to the line. The voltage injection to the line uses an ijecting transformer. The injection transformer is later replaced with injection capacitors, thus eliminating the drawback of conventional UPQC. In this way a good power quality is maintained</p>


2013 ◽  
Vol 448-453 ◽  
pp. 2551-2555
Author(s):  
Yong Hou ◽  
Shang Wen Cui ◽  
Guo Dong You ◽  
Ying Hong Duan

A new kind of parallel processing unified power quality conditioner with only one inverter is introduced. The system PI control method has a problem that the DC transient component of supply current does decay because of the linking inductance between power supply and load. A system control method based on state variable feedback is proposed, which indirectly controls the load voltage by controlling the supply current. The proposed control strategy is verified by simulation using Matlab.


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