To solve the problem of harmonic pollution to the power grid that caused by traditional diode rectifier and phase controlled rectifier, the unit power factor PWM rectifier is designed. The topology structure of the re...To solve the problem of harmonic pollution to the power grid that caused by traditional diode rectifier and phase controlled rectifier, the unit power factor PWM rectifier is designed. The topology structure of the rectifier circuit is introduced and the double closed-loop control strategy in three-phase stationary coordinate system is analyzed. For the deficiency of control strategy, the control strategy in two-phase synchronous rotating coordinate system is proposed. This makes the independent control of active current and reactive current to be realized. The simulation model of the PWM rectifier is built and the effectiveness of the control method proposed in this paper is verified by simulation.展开更多
A new type of high power LED drivers is proposed by adopting an improved two-stages non-isolated configuration. In order to improve power factor and achieve accurate average current control under universal input volta...A new type of high power LED drivers is proposed by adopting an improved two-stages non-isolated configuration. In order to improve power factor and achieve accurate average current control under universal input voltages ranging from 100 Vrms to 240 Vrms, the power factor correction and average current mode control methods operating in continuous current conduction mode are designed and implemented. With the LUMILEDS emitter type LEDs, a laboratory prototype is built and measured. And from the measured results, it could be concluded that the proposed driver has many better performances such as high power factor, low current harmonic, accurate average current control and switch protection.展开更多
An important feature of the traffic in mobile networks is burstiness. Drawbacks of conventional power control algorithms for time division duplex （TDD）-code division multiple access （CDMA） systems are analyzed. A ...An important feature of the traffic in mobile networks is burstiness. Drawbacks of conventional power control algorithms for time division duplex （TDD）-code division multiple access （CDMA） systems are analyzed. A joint power control algorithm based on service factor is presented to address the TDD-CDMA mobile services in the burst mode according to the Markov modulated Bernoulli process. The joint power control equation is derived. A function model is developed to verify the new algorithm and evaluate its performance. Simulation results show that the new power control algorithm can estimate interference strength more precisely, speed up convergence of power control, and enhance power efficiency and system capacity. It is shown that the proposed algorithm is more robust against link gain changes, and outperforms the reference algorithms.展开更多
We present an electrical grid optimization method for economical benefit. After simplifying an IEEE feeder diagram, we build a compact smart grid system including a photovoltaic-inverter system, a shunt capacitor, an ...We present an electrical grid optimization method for economical benefit. After simplifying an IEEE feeder diagram, we build a compact smart grid system including a photovoltaic-inverter system, a shunt capacitor, an on-load tapchanger(OLTC) and transmission lines. The system power factor(PF) regulation and reactive power dispatching are indispensable to improve power quality. Our control method uses predictive weather and load data to decide engaging or tripping the shunt capacitor, or reactive power injection by the photovoltaic-inverter system, ultimately to keep the system PF in a good range. From the perspective of economics, the economical model is considered as a decision maker in our predictive data control method.Capacitor-only control strategy is a common photovoltaic(PV)regulation method, which is treated as a baseline case. Simulations with GridLAB-D on profiled loads and residential loads have been carried out. The comparison results with baseline control strategy and our predictive data control method show the appreciable economical benefit of our method.展开更多
This paper presents a PFCVF (Power Factor Correction) rectifier that uses a variable frequency source for alternators for electric and hybrid vehicles application. In such application, the frequency of the signal in t...This paper presents a PFCVF (Power Factor Correction) rectifier that uses a variable frequency source for alternators for electric and hybrid vehicles application. In such application, the frequency of the signal in the alternator changes according to the vehicle speed, more over the loading effect on the alternator introduces harmonic currents and increases the alternator apparent power requirements. To overcome these problems and aiming more stability and better design of the alternator, a new third harmonic injection technique is proposed. This technique allows to preserve a good THD (Total Harmonic Distortion) of the input source at any frequency and to decrease losses in semiconductors switches, thereby allowing more stability and reducing the apparent power requirements. A comparative study between the standard and the new technique is made and highlights the effectiveness of the new design. A detailed analysis of the proposed topology is presented and simulations as well as experimental results are shown.展开更多
针对光伏系统输出功率受环境影响而呈现的非线性时变特性,以及难以稳定跟踪最大功率点(maximum power point,MPP)的问题,提出一种基于粒子群优化算法(particle swarm optimization,PSO)来优化收敛因子的光伏最大功率鲁棒控制器设计方法...针对光伏系统输出功率受环境影响而呈现的非线性时变特性,以及难以稳定跟踪最大功率点(maximum power point,MPP)的问题,提出一种基于粒子群优化算法(particle swarm optimization,PSO)来优化收敛因子的光伏最大功率鲁棒控制器设计方法。通过建立光伏阵列数学模型,引入自适应调整的学习因子与惯性权重以优化PSO算法,从而增强其全局搜索能力。同时,结合鲁棒控制理论构建H∞控制器以抑制外部扰动,并通过线性矩阵不等式配置系统极点以提升鲁棒性。实验结果表明,在局部遮挡条件下,该方法能够在0.25秒内快速跟踪到MPP,电压稳定在328 V,并且在干扰后状态变量能够迅速恢复稳定,震荡幅度降低约40%。该控制器显著提升了光伏系统在复杂环境下的动态响应与抗干扰能力,为高效、稳定的光伏发电运行提供了可靠的解决方案。展开更多
The charger of electric vehicle is a power electronic device which consists of rectifying devices and DC-DC converters. This nonlinear diode rectifier circuit has low power factor and high harmonic content. In order t...The charger of electric vehicle is a power electronic device which consists of rectifying devices and DC-DC converters. This nonlinear diode rectifier circuit has low power factor and high harmonic content. In order to improve power factor and reduce the harmonic distortion rate of the AC side current, single-phase non-controlled rectifier charger needs to install the active power factor correction device. A piece of power system analysis software which is called PSCAD is used in modeling of an EV charger which contains Boost-APFC. By means of simulation and analysis, differences of APFC characteristics between the hysteresis current control mode and average current control mode which has an influence on the power grid are compared. The consequence of simulation shows that the two control strategies achieve power factor correction and harmonic reduction requirements;Boost type power conversion circuit employs the average current control mode is better, which has following features: relatively faster settling time of the output voltage, relatively smaller overshoot, lower current harmonic distortion rate on AC side, lower switching frequency and better control effect.展开更多
The distributed generator over the last 30years has posed several challenges when they are connected to a distributed network.The most immediate problem is to change the voltage at the connection point depending on th...The distributed generator over the last 30years has posed several challenges when they are connected to a distributed network.The most immediate problem is to change the voltage at the connection point depending on the power supplied to the network and may cause it to exceed statutory limits.This paper describes a new control scheme for a distributed generator for supporting the voltage control in the network,thus ensuring the distributed generator to contribute to network voltage management.The scheme performance is demonstrated by a model for a distributed generator connected to a distribution network.The result shows that using the new control scheme,the distribution network voltage constraints are maintained while maximizing the active power delivered by distributed generators.展开更多
To provide electrical power for the Research System of Superconducting Magnets(RSSMs)including the background field superconducting magnet and the tested superconducting objects,the high power phase-controlled convert...To provide electrical power for the Research System of Superconducting Magnets(RSSMs)including the background field superconducting magnet and the tested superconducting objects,the high power phase-controlled converter will be used to develop the power supply system.However, because of its inner nonlinear feature, the current harmonics and the reactive power are injected into the AC power supply system. To improve the quality of the power supply system for RSSMs, an improved synchronous control strategy is suggested for the superconducting magnet power supply system, which comprises four series-connected six-pulse converters fed by a phase-shifting transformer, respectively. According to the proposed control strategy, the basic unit is two 12-pulse converters and the control method will be changed in terms of loadfluctuations which are represented by the per unit value of converter output voltage. As a result,harmonic is greatly reduced but the power factor is also high.展开更多
In this paper, the Author presents the theory and application of repetitive proportional integral current con-troller for boost single phase ac-dc converter with power factor correction (PFC). A repetitive controller ...In this paper, the Author presents the theory and application of repetitive proportional integral current con-troller for boost single phase ac-dc converter with power factor correction (PFC). A repetitive controller which is inserted in series with the proportional integral ( PI) controller shows very low crossover distortion of input current, low total harmonic distortion and very low tracking error when is compared with the con-ventional proportional integral controller. Full analysis of proposed controller is given and Matlab/Simulink is used for simulation. The simulation results show the validity of the proposed control method.展开更多
文摘To solve the problem of harmonic pollution to the power grid that caused by traditional diode rectifier and phase controlled rectifier, the unit power factor PWM rectifier is designed. The topology structure of the rectifier circuit is introduced and the double closed-loop control strategy in three-phase stationary coordinate system is analyzed. For the deficiency of control strategy, the control strategy in two-phase synchronous rotating coordinate system is proposed. This makes the independent control of active current and reactive current to be realized. The simulation model of the PWM rectifier is built and the effectiveness of the control method proposed in this paper is verified by simulation.
文摘A new type of high power LED drivers is proposed by adopting an improved two-stages non-isolated configuration. In order to improve power factor and achieve accurate average current control under universal input voltages ranging from 100 Vrms to 240 Vrms, the power factor correction and average current mode control methods operating in continuous current conduction mode are designed and implemented. With the LUMILEDS emitter type LEDs, a laboratory prototype is built and measured. And from the measured results, it could be concluded that the proposed driver has many better performances such as high power factor, low current harmonic, accurate average current control and switch protection.
基金Project supported by the National Science Foundation for Creative Research Groups （Grant No.60521002）, and the National Key Technologies R＆D Program （Grant No.2005BA908B02）
文摘An important feature of the traffic in mobile networks is burstiness. Drawbacks of conventional power control algorithms for time division duplex （TDD）-code division multiple access （CDMA） systems are analyzed. A joint power control algorithm based on service factor is presented to address the TDD-CDMA mobile services in the burst mode according to the Markov modulated Bernoulli process. The joint power control equation is derived. A function model is developed to verify the new algorithm and evaluate its performance. Simulation results show that the new power control algorithm can estimate interference strength more precisely, speed up convergence of power control, and enhance power efficiency and system capacity. It is shown that the proposed algorithm is more robust against link gain changes, and outperforms the reference algorithms.
文摘We present an electrical grid optimization method for economical benefit. After simplifying an IEEE feeder diagram, we build a compact smart grid system including a photovoltaic-inverter system, a shunt capacitor, an on-load tapchanger(OLTC) and transmission lines. The system power factor(PF) regulation and reactive power dispatching are indispensable to improve power quality. Our control method uses predictive weather and load data to decide engaging or tripping the shunt capacitor, or reactive power injection by the photovoltaic-inverter system, ultimately to keep the system PF in a good range. From the perspective of economics, the economical model is considered as a decision maker in our predictive data control method.Capacitor-only control strategy is a common photovoltaic(PV)regulation method, which is treated as a baseline case. Simulations with GridLAB-D on profiled loads and residential loads have been carried out. The comparison results with baseline control strategy and our predictive data control method show the appreciable economical benefit of our method.
文摘This paper presents a PFCVF (Power Factor Correction) rectifier that uses a variable frequency source for alternators for electric and hybrid vehicles application. In such application, the frequency of the signal in the alternator changes according to the vehicle speed, more over the loading effect on the alternator introduces harmonic currents and increases the alternator apparent power requirements. To overcome these problems and aiming more stability and better design of the alternator, a new third harmonic injection technique is proposed. This technique allows to preserve a good THD (Total Harmonic Distortion) of the input source at any frequency and to decrease losses in semiconductors switches, thereby allowing more stability and reducing the apparent power requirements. A comparative study between the standard and the new technique is made and highlights the effectiveness of the new design. A detailed analysis of the proposed topology is presented and simulations as well as experimental results are shown.
文摘The charger of electric vehicle is a power electronic device which consists of rectifying devices and DC-DC converters. This nonlinear diode rectifier circuit has low power factor and high harmonic content. In order to improve power factor and reduce the harmonic distortion rate of the AC side current, single-phase non-controlled rectifier charger needs to install the active power factor correction device. A piece of power system analysis software which is called PSCAD is used in modeling of an EV charger which contains Boost-APFC. By means of simulation and analysis, differences of APFC characteristics between the hysteresis current control mode and average current control mode which has an influence on the power grid are compared. The consequence of simulation shows that the two control strategies achieve power factor correction and harmonic reduction requirements;Boost type power conversion circuit employs the average current control mode is better, which has following features: relatively faster settling time of the output voltage, relatively smaller overshoot, lower current harmonic distortion rate on AC side, lower switching frequency and better control effect.
基金supported by EPSRC SUPERGEN 1 Renewal Core-FlexNet:Renewal of the Supergen Consortium on Future Network Technologies.EPSRC GRANT Reference EP/E4011X/1
文摘The distributed generator over the last 30years has posed several challenges when they are connected to a distributed network.The most immediate problem is to change the voltage at the connection point depending on the power supplied to the network and may cause it to exceed statutory limits.This paper describes a new control scheme for a distributed generator for supporting the voltage control in the network,thus ensuring the distributed generator to contribute to network voltage management.The scheme performance is demonstrated by a model for a distributed generator connected to a distribution network.The result shows that using the new control scheme,the distribution network voltage constraints are maintained while maximizing the active power delivered by distributed generators.
基金supported by National Natural Science Foundation of China (No. 51877001)
文摘To provide electrical power for the Research System of Superconducting Magnets(RSSMs)including the background field superconducting magnet and the tested superconducting objects,the high power phase-controlled converter will be used to develop the power supply system.However, because of its inner nonlinear feature, the current harmonics and the reactive power are injected into the AC power supply system. To improve the quality of the power supply system for RSSMs, an improved synchronous control strategy is suggested for the superconducting magnet power supply system, which comprises four series-connected six-pulse converters fed by a phase-shifting transformer, respectively. According to the proposed control strategy, the basic unit is two 12-pulse converters and the control method will be changed in terms of loadfluctuations which are represented by the per unit value of converter output voltage. As a result,harmonic is greatly reduced but the power factor is also high.
文摘In this paper, the Author presents the theory and application of repetitive proportional integral current con-troller for boost single phase ac-dc converter with power factor correction (PFC). A repetitive controller which is inserted in series with the proportional integral ( PI) controller shows very low crossover distortion of input current, low total harmonic distortion and very low tracking error when is compared with the con-ventional proportional integral controller. Full analysis of proposed controller is given and Matlab/Simulink is used for simulation. The simulation results show the validity of the proposed control method.
