Novel Control Strategy for a UPQC under Distorted Source and Nonlinear Load Conditions

Trinh, Quoc-Nam,Lee, Hong-Hee The Korean Institute of Power Electronics 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.1

This paper proposes a novel control strategy for a unified power quality conditioner (UPQC) including a series and a shunt active power filter (APF) to compensate the harmonics in both the distorted supply voltage and the nonlinear load current. In the series APF control scheme, a proportional-integral (PI) controller and a resonant controller tuned at six multiples of the fundamental frequency of the network ($6{\omega}_s$) are performed to compensate the harmonics in the distorted source. Meanwhile, a PI controller and three resonant controllers tuned at $6n{\omega}_s$(n=1, 2, 3) are designed in the shunt APF control scheme to mitigate the harmonic currents produced by nonlinear loads. The performance of the proposed UPQC is significantly improved when compared to that of the conventional control strategy thanks to the effective design of the resonant controllers. The feasibility of the proposed UPQC control scheme is validated through simulation and experimental results.

Advanced Repetitive Controller to Improve the Voltage Characteristics of Distributed Generation with Nonlinear Loads

Trinh, Quoc-Nam,Lee, Hong-Hee The Korean Institute of Power Electronics 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.3

This paper presents an enhanced control strategy which consists of a proportional-integral controller and a repetitive controller (RC) for improving the voltage performance of distributed generation (DG) under nonlinear load conditions. The proposed voltage controller is able to maintain a sinusoidal voltage at the point of common coupling (PCC) of the DG regardless of the harmonic voltage drop in the system impedance due to nonlinear load currents. In addition, by employing the delay time of the RC at one-sixth of the fundamental period, the proposed RC can overcome the slow response drawback of the traditional PI-RC. The proposed control strategy is analyzed and the design of the RC is presented in detail. The feasibility of the proposed control strategy is verified through simulation and experimental results.

An Enhanced Harmonic Voltage Compensator for General Loads in Stand-alone Distributed Generation Systems

Trinh, Quoc-Nam,Lee, Hong-Hee,Chun, Tae-Won The Korean Institute of Power Electronics 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.6

This paper develops an enhanced harmonic voltage compensator which is implemented with the aid of two repetitive controllers (RCs) in order to improve the output voltage performance of stand-alone distributed generation (DG) systems. The proposed harmonic voltage compensator is able to maintain the DG output voltage sinusoidal regardless of the use of nonlinear and/or unbalanced loads in the load side. In addition, it can offer good steady-state performance under various types of loads and a very fast dynamic response under load variations to overcome the slow dynamic response issue of the traditional RC. The feasibility of the proposed control strategy is verified through simulations and experiments.

Novel Control Strategy for a UPQC under Distorted Source and Nonlinear Load Conditions

Quoc-Nam Trinh,Hong-Hee Lee 전력전자학회 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.1

This paper proposes a novel control strategy for a unified power quality conditioner (UPQC) including a series and a shunt active power filter (APF) to compensate the harmonics in both the distorted supply voltage and the nonlinear load current. In the series APF control scheme, a proportional-integral (PI) controller and a resonant controller tuned at six multiples of the fundamental frequency of the network ( 6ωS) are performed to compensate the harmonics in the distorted source. Meanwhile, a PI controller and three resonant controllers tuned at 6nωS (n=1, 2, 3) are designed in the shunt APF control scheme to mitigate the harmonic currents produced by nonlinear loads. The performance of the proposed UPQC is significantly improved when compared to that of the conventional control strategy thanks to the effective design of the resonant controllers. The feasibility of the proposed UPQC control scheme is validated through simulation and experimental results.

A New Control Strategy for Distributed Generation under Nonlinear loads

Quoc-Nam Trinh,Hong-Hee Lee 전력전자학회 2012 전력전자학술대회 논문집 Vol.2012 No.7

A New Z-Source Inverter Topology to Improve Voltage Boost Ability

Quoc-Nam Trinh,Hong-Hee Lee,Tae-Won Chun 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

In this paper, a new Z-source inverter (ZSI) topology is developed to improve a voltage boost ability of ZSI. Some more inductors and diodes are added into the impedance network of the conventional ZSI. The modulation methods that have been developed in the conventional ZSI can be easily utilized in the proposed ZSI. The voltage boost ratio becomes much higher compared with the conventional ZSI under the same shoot-through duty ratio. In addition, the proposed ZSI can reduce the voltage stress on Z-source capacitor and inverter-bridge significantly because a smaller shoot-through duty ratio is required for high voltage boost ratio. Theoretical analysis of the proposed topology is investigated and the improved performances are validated by both simulation study and experimental results.

Advanced Repetitive Controller to Improve the Voltage Characteristics of Distributed Generationwith Nonlinear Loads

Quoc-Nam Trinh,Hong-Hee Lee 전력전자학회 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.3

This paper presents an enhanced control strategy which consists of a proportional-integral controller and a repetitive controller (RC) for improving the voltage performance of distributed generation (DG) under nonlinear load conditions. The proposed voltage controller is able to maintain a sinusoidal voltage at the point of common coupling (PCC) of the DG regardless of the harmonic voltage drop in the system impedance due to nonlinear load currents. In addition, by employing the delay time of the RC at one-sixth of the fundamental period, the proposed RC can overcome the slow response drawback of the traditional PI-RC. The proposed control strategy is analyzed and the design of the RC is presented in detail. The feasibility of the proposed control strategy is verified through simulation and experimental results.

A New Z-Source Inverter Topology with High Voltage Boost Ability

Quoc-Nam Trinh,Hong-Hee Lee 대한전기학회 2012 Journal of Electrical Engineering & Technology Vol.7 No.5

A new Z-source inverter (ZSI) topology is developed to improve voltage boost ability. The proposed topology is modified from the switched inductor topology by adding some more inductors and diodes into inductor branch to the conventional Z-source network. The modulation methods developed for the conventional ZSI can be easily utilized in the proposed ZSI. The proposed ZSI has an ability to obtain a higher voltage boost ratio compared with the conventional ZSI under the same shoot-through duty ratio. Since a smaller shoot-through duty ratio is required for high voltage boost, the proposed ZSI is able to reduce the voltage stress on Z-source capacitor and inverter-bridge. Theoretical analysis and operating principle of the proposed topology are explicitly described. In addition, the design guideline of the proposed Z-source network as well as the PWM control method to achieve the desired voltage boost factor is also analyzed in detail. The improved performances are validated by both simulation and experiment.

An Enhanced Harmonic Voltage Compensator for General Loads in Stand-alone Distributed Generation Systems

Quoc-Nam Trinh,Hong-Hee Lee,Tae-Won Chun 전력전자학회 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.6

This paper develops an enhanced harmonic voltage compensator which is implemented with the aid of two repetitive controllers (RCs) in order to improve the output voltage performance of stand-alone distributed generation (DG) systems. The proposed harmonic voltage compensator is able to maintain the DG output voltage sinusoidal regardless of the use of nonlinear and/or unbalanced loads in the load side. In addition, it can offer good steady-state performance under various types of loads and a very fast dynamic response under load variations to overcome the slow dynamic response issue of the traditional RC. The feasibility of the proposed control strategy is verified through simulations and experiments.

Low Cost and High Performance UPQC with Four-Switch Three-Phase Inverters

Trinh, Quoc-Nam,Lee, Hong-Hee The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.3

This paper introduces a low cost, high efficiency, high performance three-phase unified power quality conditioner (UPQC) by using four-switch three-phase inverters (FSTPIs) and an extra capacitor in the shunt active power filter (APF) side of the UPQC. In the proposed UPQC, both shunt and series APFs are developed by using FSTPIs so that the number of switching devices is reduced from twelve to eight devices. In addition, by inserting an additional capacitor in series with the shunt APF, the DC-link voltage in the proposed UPQC can also be greatly reduced. As a result, the system cost and power loss of the proposed UPQC is significantly minimized thanks to the use of a smaller number of power switches with a lower rating voltage without degrading the compensation performance of the UPQC. Design of passive components for the proposed UPQC to achieve a good performance is presented in detail. In addition, comparisons on power loss, overall system efficiency, compensation performance between the proposed UPQC and the traditional one are also determined in this paper. Simulation and experimental studies are performed to verify the validity of the proposed topology.