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A Fast-Transient Repetitive Control Strategy for Programmable Harmonic Current Source
Lei, Wanjun,Nie, Cheng,Chen, Mingfeng,Wang, Huajia,Wang, Yue The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.1
The repetitive control (RC) strategy is widely used in AC power systems because of its high performance in tracking period signal and suppressing steady-state error. However, the dynamic response of RC is determined by the fundamental period delay $T_0$ existing in the internal model. In the current study, a ($nk{\pm}i$)-order harmonic RC structure is proposed to improve dynamic performance. The proposed structure has less data memory and can improve the tracking speed by n/2 times. $T_0$ proves the effectiveness of the ($nk{\pm}i$)-order RC strategy. The simulation and experiments of ($6k{\pm}1$)-order and ($4k{\pm}1$)-order RC strategy used in the voltage source inverter is conducted in this study to control the harmonic current source, which shows the validity and advantages of the proposed structure.
A Fast-Transient Repetitive Control Strategy for Programmable Harmonic Current Source
Wanjun Lei,Cheng Nie,Mingfeng Chen,Huajia Wang,Yue Wang 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.1
The repetitive control (RC) strategy is widely used in AC power systems because of its high performance in tracking period signal and suppressing steady-state error. However, the dynamic response of RC is determined by the fundamental period delay T0 existing in the internal model. In the current study, a (nk ± i)-order harmonic RC structure is proposed to improve dynamic performance. The proposed structure has less data memory and can improve the tracking speed by n/2 times. T0 proves the effectiveness of the (nk ± i)-order RC strategy. The simulation and experiments of (6k ± 1)-order and (4k ± 1)-order RC strategy used in the voltage source inverter is conducted in this study to control the harmonic current source, which shows the validity and advantages of the proposed structure.
Guoqing Gao,Wanjun Lei,Gaotai Lv,Kai Li,Yao Cui,Tian Li 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
This paper proposes a novel ripple recovery technique for the dual active bridge (DAB) converter. The proposed technique reveals the limitation of the conventional discrete-time modeling method in the output-voltage-ripple analysis of the DAB converter. Two previously unrecognized output voltage states are recovered by the ripple recovery technique, which can reveal the detailed information of the output voltage. The output-voltage-ripple analysis under different parameters can be utilized to discover the key parameters to the output voltage ripple. Besides, the parameter borders under different ripple requirement are obtained, which can give a guidance for the practical parameter design. Finally, the simulation and theoretical analysis are verified by the experimental results.
Cheng Nie,Wanjun Lei,Huajia Wang,Kai Zhang,Yue Wang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
In the microgrid, the capacitive element such as compensation capacitor may resonance with the line inductance in harmonic frequency, furthermore serious harmonic resonance may endanger the system. In this paper, resonance mode analysis (RMA) method is used to analysis the harmonic resonance in the microgrid. To suppress the amplified of harmonic current near resonance frequency, an improved current control method for active harmonic resistance (AHR) is proposed. Simulation and experimental results reveal that the proposed method can suppress the resonance in the microgrid effectively.
Research on Hybrid Dynamic Capacitor-a novel approach to VAR compensation and resonance suppression
Zhang Kai,Lei Wanjun,Cheng Nie,Yue Wang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
In this paper, a control method named hybrid dynamic capacitor is proposed to provide dynamic VAR compensation and suppress resonance between power capacitor and system inductance in power distribution network. This paper explains the theory of hybrid dynamic capacitor and this method benefits by reducing the initial cost, switching loss and less harmonic current. Finally, simulation and experiment results are given to verify the viability and effectiveness of the hybrid dynamic capacitor and its compensation characteristic.
Research on Multi-frequency Current Tracking Control of Three-phase Grid-connected VSI
Chongfu XU,Wanjun LEI,Gaidi NING,Xiang ZHANG,Yue WANG,Jinjun LIU 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
This paper proposes a multi-frequency current tracking control method which can be applied in the application of APF(Active Power Filter), programmable current source etc. Because the method based on the stationary PI inner loop and the dq outer loop can’t be used in the case of high frequency, a new method is proposed. The proposed method includes a stationary PI inner loop and an Amplitude-Phase outer loop, which can realize separate control of each harmonic in each phase precisely in a wide frequency range, and keep the advantages of the stationary PI method: the anti-interference ability, low harmonic distortion in the line current, fast response speed and simple control. The parameter design method of both loops is also described. At last, simulation results based on PSCAD/EMTDC and experimental results are given to prove the feasibility of this method.
Analysis of Harmonic Transfer Characteristics and RAPF Installation Strategy in Power Systems
Tian Li,Wanjun Lei,Nie Cheng,Xiaojie Zhang,Guoqing Gao,F. Kai Li 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
Power quality has become a new threat because of the distributed nature of disturbances caused by nonlinear loads and DGs. When harmonics are transmitted in a distribution network, they’ll be magnified by resonance between line capacitance and inductance, then worsen the harmonic in power systems. In this paper, a mathematical model for harmonic transfer characteristics of power system feeders is firstly established. Meanwhile, analyze the harmonic voltage propagation caused respectively by the background harmonic voltage source and harmonic current source, which provides an important theoretical basis for the treatment of harmonic pollution. In addition, a strategy is proposed to guide the optimal installation position and setting of external resistance of RAPF to achieve the minimum total distortion rate in the entire distribution network system, which can damp the harmonic resonant effectively. Simulation and experiments have been performed to verify the theoretical analysis and demonstrate the effectiveness of the proposed strategy.
Ning Li,Yue Wang,Wanjun Lei,Ruigen Niu,Zhao’an Wang 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.3
A novel carrier-based PWM (CBPWM) strategy of a three-level NPC converter is proposed in this paper. The novel strategy can eliminate the low-frequency neutral point (NP) voltage oscillation under the entire modulation index and full power factor. The basic principle of the novel strategy is introduced. The internal modulation wave relationship between the novel CBPWM strategy and traditional SPWM strategy is also studied. All 64 modulation wave solutions of the CBPWM strategy are derived. Furthermore, the proposed CBPWM strategy is compared with traditional SPWM strategy regarding the output phase voltage THD characteristics, DC voltage utilization ratio, and device switching losses. Comparison results show that the proposed strategy does not cause NP voltage oscillation. As a result, no low-frequency harmonics occur on output line-to-line voltage and phase current. The novel strategy also has higher DC voltage utilization ratio (15.47% higher than that of SPWM strategy), whereas it causes larger device switching losses (4/3 times of SPWM strategy). The effectiveness of the proposed modulation strategy is verified by simulation and experiment results.
Li, Ning,Wang, Yue,Lei, Wanjun,Niu, Ruigen,Wang, Zhao'an The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.3
A novel carrier-based PWM (CBPWM) strategy of a three-level NPC converter is proposed in this paper. The novel strategy can eliminate the low-frequency neutral point (NP) voltage oscillation under the entire modulation index and full power factor. The basic principle of the novel strategy is introduced. The internal modulation wave relationship between the novel CBPWM strategy and traditional SPWM strategy is also studied. All 64 modulation wave solutions of the CBPWM strategy are derived. Furthermore, the proposed CBPWM strategy is compared with traditional SPWM strategy regarding the output phase voltage THD characteristics, DC voltage utilization ratio, and device switching losses. Comparison results show that the proposed strategy does not cause NP voltage oscillation. As a result, no low-frequency harmonics occur on output line-to-line voltage and phase current. The novel strategy also has higher DC voltage utilization ratio (15.47% higher than that of SPWM strategy), whereas it causes larger device switching losses (4/3 times of SPWM strategy). The effectiveness of the proposed modulation strategy is verified by simulation and experiment results.