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- 저자 : Keqing. Qu (검색결과 7 건)
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Keqing Qu,Yi Liu,Zhenxiang Liu,Jinbin Zhao,Zhiwei Zeng,Ling Mao 전력전자학회 2025 JOURNAL OF POWER ELECTRONICS Vol.25 No.5
With the rapid growth of distributed renewable energy sources, the dynamics and complexity of DC microgrid systems have increased, posing challenges to the small-signal stability of systems. This paper primarily investigates the small-signal stability issues of the Multi Converter DC Microgrid (MCDCM) and utilizes impedance analysis to obtain the negative feedback model of the system. To further enhance system stability and identify potential instability factors, a novel method based on the generalized Nyquist criterion is proposed for identifying participation factors. This method allows for the derivation of sensitivity curves to quantitatively analyze the impact of parameters on stability. Finally, a microgrid system with six converter clusters is constructed, and an analysis is conducted using participation factors such as the bus capacitance and energy storage droop coefficient. The feasibility of the proposed schemes is verified through frequency domain analysis and RT-LAB hardware in the loop experiments. This study provides a theoretical basis for the stable operation of microgrids and the identification of participation factors.
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PQ Control of Micro Grid Inverters with Axial Voltage Regulators
Yang Chen,Jinbin Zhao,Keqing Qu,Fen Li 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.6
This paper presents a PQ control strategy for micro grid inverters with axial voltage regulators. The inverter works in the voltage-controlled mode and can help improve the terminal power quality. The inverter has two axial voltage regulators. The 1st regulator involves the output voltage amplitude and output impedance, while the 2nd regulator controls the output frequency. The inverter system is equivalent to a controllable voltage source with a controllable inner output impedance. The basic PQ control for micro grid inverters is easy to accomplish. The output active and reactive powers can be decoupled well by controlling the two axial voltages. The 1st axial voltage regulator controls the reactive power, while the 2nd regulator controls the active power. The paper analyses the axial voltage regulation mechanism, and evaluates the PQ decoupling effect mathematically. The effectiveness of the proposed control strategy is validated by simulation and experimental results.
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PQ Control of Micro Grid Inverters with Axial Voltage Regulators
Chen, Yang,Zhao, Jinbin,Qu, Keqing,Li, Fen The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.6
This paper presents a PQ control strategy for micro grid inverters with axial voltage regulators. The inverter works in the voltage-controlled mode and can help improve the terminal power quality. The inverter has two axial voltage regulators. The 1st regulator involves the output voltage amplitude and output impedance, while the 2nd regulator controls the output frequency. The inverter system is equivalent to a controllable voltage source with a controllable inner output impedance. The basic PQ control for micro grid inverters is easy to accomplish. The output active and reactive powers can be decoupled well by controlling the two axial voltages. The 1st axial voltage regulator controls the reactive power, while the 2nd regulator controls the active power. The paper analyses the axial voltage regulation mechanism, and evaluates the PQ decoupling effect mathematically. The effectiveness of the proposed control strategy is validated by simulation and experimental results.
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Stability Analysis and Evaluation of ESR for Hysteresis Controlled Buck Converter
Jinlong WANG,Jinbin ZHAO,Jianfeng DAI,Keqing QU,Tiankai YE 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
Buck converter using hysteresis controller has been widely used for power supply in industry applications owing to its instantaneous load transient. However the equivalent series resistance (ESR) of output capacitor has a significant effect for the stability performance. In this paper, the critical value of ESR is analyzed and calculated in the hysteresis controlled buck converter. Finally, simulation results indicate that the larger output capacitor ESR is necessary to make sure the converter operate normally, otherwise, the converter will operate abnormally.
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A Decupled PQ Control strategy of Voltage - Controlled Inverters
Yang Chen,Jinbin Zhao,Jinlong Wang,Keqing Qu,Shuuichi Ushiki,Masaaki Ohshima 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
This paper deals with problems caused by high distributed generation penetration and proposes a simple and precise PQ control strategy for voltage-controlled inverters in micro grids. The widely-used current-controlled inverters cannot provide voltage support for micro grids and have to develop seamless transfer strategy between gird connected mode and islanded mode. A voltage-controlled inverter is raised in the paper due to the problems. The new inverter can be regarded as a voltage source cascaded with controllable output impedance. By adopting a new phase-locked loop, the output voltage amplitude and frequency are well decoupled. Thus output active and reactive powers are decoupled satisfactory. The output response is fast and precise. The idea is verified by simulation and experiment results.
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Evaluating optimum tilt angle for PV modules using solar radiation models in Wuhan, China
Fen. Li,Nianjun. Ma,Jinbin. Zhao,Keqing. Qu,Xingwu. Yang,Zhenghong. Chen 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
Four models are used to estimate the hourly solar radiation on 15 pieces of different tilted photovoltaic (PV) modules in Wuhan, China based on power and solar radiation data during a whole year. The optimum tilt angle (OTA) in Wuhan for yearly and semi-yearly adjustment was determined. Then it was determined that the best mode is the tilt angle of PV module adjusted every half a year. In semi-yearly adjustment, OTA in semi-year of winter and summer is found as 45°, 15°, respectively. Experimental results verify the theoretical calculated values of the OTA with high precision. Energy radio (ER) reveals PV modules with adjustment of tilt angle twice a year has a capability to improve nearly 7% in comparison with fixed type. The best model was chosen based on test results from statistical indicators. The statistical results demonstrate that among the studied models, Liu&Jordan model is the most accurate.
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Ling Mao,Yubin Wang,Jinbin Zhao,Chao Pan,Keqing Qu 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.3
This paper proposes a multi-vector predictive direct power control (P-DPC) for grid-tied T-type three-level inverters with optimized vector application time calculations. The conventional multi-vector P-DPC suffers from the problems of a heavy computational burden and a tedious adjustment process for the weighting factor. To reduce the computational burden, this paper proposes a new space vector division method. The proposed method can reduce the number of candidate vectors and the number of iterations for the cost function. To avoid the need for adjusting the weighting factor, the redundant small vectors are utilized to balance the neutral point voltage. In addition, the Lagrange multiplier method is introduced to optimize the calculation of the prediction vector application time, which improves the control accuracy. Finally, the effectiveness of the proposed method is verified in a hardware-in-the-loop platform.
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