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《International Journal of Circuit Theory and Applications》2017,45(4):571-591
Conventionally, a high accuracy operational amplifier (OPA)‐based current sensor is used for sensing current message under a full load range, which increases the cost characteristic. Instead of a high accuracy OPA‐based current sensor, this paper describes using a switching inductor quasi‐V2 hysteretic control boost dc–dc regulator with a proposed current‐sensing technique named emulated‐ramp feedback (ERF), which can improve transfer efficiency under a full load range. Two control systems are presented in this paper. The first system, a hysteretic voltage control switching boost converter with ERF, achieves the hysteretic voltage control in a boost regulator and lowers the cost characteristic without using compensator. The second system, a quasi‐V2 hysteretic voltage control switching boost converter with ERF, demonstrates the compatibility of ERF technique in rippled‐based control boost converters. The regulator was implemented with TSMC 0.25‐µm HV CMOS process. Experimental results show the second system can work under the specification of 5–12 V with a 0 to 300‐mA load range. Additionally, this system attained a recovery time is 27/95 µs for step‐up/step‐down in a 100 to 300‐mA continuous conduction mode load current, and a peak efficiency of 92.1% with a chip area of only 1.014 mm2. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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The paper presents the bacterial foraging optimization algorithm (BFOA) and particle swarm optimization (PSO) algorithm based robust controllers for voltage deviations due to the variation of reactive power in an isolated wind-diesel hybrid power system. The isolated wind-diesel system consists of wind energy conversion system (WECS) utilizing a permanent magnet induction generator (PMIG). Further, a synchronous generator (SG) is used with the diesel engine set for power generation. The mismatch between generated and consumed reactive power in the system causes voltage fluctuations, which will occur at generator terminals. These oscillations further causes reduction in the stability and quality of the power supply. The static synchronous compensator (STATCOM) and an automatic voltage regulator (AVR) are used to suppress voltage fluctuations in an isolated wind-diesel hybrid power system. The STATCOM is used as a reactive power compensator and the AVR is used to keep the terminal voltage constant for the synchronous generator. Both STATCOM and AVR are having proportional and integral (PI) controllers with single input. In modeling for the system, a normalized co-prime factorization is applied to show the possible unstructured uncertainties in the power system such as variation of system parameters and generating and loading conditions. The performance and robust stability conditions of the control system are formulated as the optimization problem, which is based on the Hα loop shaping. BFOA and PSO algorithms are implemented to solve this optimization problem and to achieve PI control parameters of STATCOM and AVR simultaneously. In order to show the efficiency of the proposed controllers, the performance of the proposed controllers is compared with the performance of the conventional controller and genetic algorithm (GA) based PI controllers for the same wind-diesel system. The dynamic responses of the system for four different small-disturbance case studies has been carried out in MATLAB environment. 相似文献
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In this paper, the design of a distribution static compensator (DSTATCOM) based on cascaded transformer multilevel inverter is proposed. The topology requires controlling only a common dc storage capacitor. Two-level ramp-comparison current control method is extended for the multilevel inverter using phase-shifted multi-carrier PWM. The method provides equal switching stress and power handling for all the cascaded units. The net switching frequency increases while the ripple magnitude reduces using multilevel topology. These cause the feedforward gain to increase leading to a higher bandwidth of the control loop. An expression of the feedforward gain is derived for fixed switching frequency modulation of the inverter. It is shown that the use of proportional plus resonant controller with proposed multilevel modulation improves the tracking characteristics at fundamental frequency. A seven-level inverter based DSTATCOM is proposed for the application to the three-phase medium voltage distribution system and the results are shown through the PSCAD/EMTDC simulation. The proposed modulation and control scheme is validated through the experimental results that are obtained using the laboratory model of a single-phase, five-level inverter based DSTATCOM. 相似文献
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微电网的主要特点之一是能够在并网模式和孤岛模式下运行,进行微电网运行模式之间的切换可能导致电压和频率的显著波动,严重时会威胁到整个系统的稳定性。无缝切换控制策略是保证微电网稳定可靠运行的关键,为解决传统无缝切换控制策略易受干扰影响和动态稳定性差的问题,提出了一种基于改进线性二次调节器的微电网运行模式无缝切换控制策略,该策略包括并网-孤岛平滑调节器和孤岛-并网平滑调节器。并网-孤岛平滑调节器通过对传统电压控制环的改进,可以为系统提供更多的阻尼并补偿逆变器输出处的瞬态电压降,从而改善系统动态性能。同时,通过对传统下垂控制策略的改进,可以根据系统有功功率的变化来调整其下垂系数,在受干扰的情况下能够将频率偏差降低到期望的水平。孤岛-并网平滑调节器考虑内部控制回路和PLL动态的情况下,根据并网控制策略下的状态空间模型对传统电流控制回路进行了改进,可以保证PCC两侧电压的同步性和微电网频率的稳定性。最后,对所提出的控制策略进行了小信号分析,同时研究了孤岛检测算法对控制策略的潜在影响,突出了所提策略的鲁棒性,并验证了所提控制策略能够平滑稳定地实现微电网运行模式间的切换。 相似文献
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将基于预测模型的功率控制策略(Predictive power control,PPC)应用于静止同步补偿器(Static synchronous compensator,STATCOM)中,来解决传统直接功率控制策略中存在的功率脉动过大、开关频率不固定等问题。在分析STATCOM基本结构的基础上,结合实际数字处理系统离散运行的特点,推导出STATCOM系统的功率预测方程,构建一个使k+1采样点功率跟踪误差最小为目标的占空比求取函数,然后利用SVPWM技术调制出波形控制(Voltage source inverter,VSI),以达到系统的稳定运行。最后,使用Matlab搭建了STATCOM系统仿真模型,仿真结果表明所提PPC策略有效地抑制了系统的功率脉动、恒定系统的开关频率,同时其保留了传统DPC策略高动态响应的优异特性。 相似文献
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A device for improving the power factor for ac electric locomotives that are based on an adjustable passive reactive-power compensator is described. This compensator configuration allows an increase in the power factor of an electric locomotive in all its operating modes. The control of the compensator unit is based on the method of extremal voltage control at the output of an autonomous voltage inverter (AVI). The voltage is chosen on the basis of the numerical differentiation of the dependence of the power factor on the AVI voltage. The mathematical simulation of the operation of the compensator with an extremal regulator, which was performed in the MATLAB package, showed that the proposed device is highly efficient. 相似文献
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This paper presents two novel control schemes for static synchronous series compensator (SSSC) for dynamic series compensation and voltage regulation. The SSSC model comprises a harmonic neutralized multilevel 48 pulse voltage source converter. This paper investigates two novel control schemes for optimal series compensation, which are indirect control (constant reactance control) and direct control (constant voltage control) using pulse width modulation (PWM) switching techniques. The proposed model of SSSC within the power system is performed in Matlab/Simulink using the power system blockset. The performance of the SSSC schemes connected to the 230 kV grid is evaluated in both capacitive and inductive modes of operation under load excursions. The operation of the proposed controllers is also tested in a weak power in order to compare their performance for securing SSSC stability in response to system contingencies. 相似文献
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This paper presents a mathematical model of a doubly fed induction generator (DFIG) based on stator voltage orientation (SVO) in the positive and negative synchronous reference frames under unbalanced grid voltage conditions. The oscillations of the DFIG electromagnetic torque and the stator active and reactive powers are fully described during grid voltage unbalance. A new rotor current controller implemented in the positive synchronous reference frame is proposed. The controller consists of a proportional integral (PI) regulator and a harmonic resonant (R) compensator tuned at twice the grid frequency. Thus, the positive and negative sequence components of DFIG rotor currents are directly regulated by the PI + R controller without the need of involving positive and negative sequence decomposition, which indeed improves the dynamic performance of DFIG-based wind power generation system during small steady-state and relatively larger transient network unbalances. The theoretical analysis and the feasibility of the proposed unbalanced control scheme are validated by simulation studies on a 1.5-MW wind-turbine driven DFIG system. Compared with conventional single PI current control design, the proposed control scheme results in significant elimination of either DFIG power or torque oscillation under unbalanced grid voltage conditions. 相似文献
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ABSTRACT Current-controlled voltage source inverters offer substantial advantages in improving motor system dynamics for high-performance ac drive systems. The controller switches follow a set of reference current waveforms. Fixed-band hysteresis and sinusoidal-band hysteresis controllers have been studied. The first part of this paper develops neural network and fuzzy logic based current-controlled voltage source inverters. The models and learning techniques have been investigated by simulation. The implementation of neural networks is described and simulation results are presented. In the second part of this paper, the new UPS (uninterruptible power supply) with fuzzy logic compensator is proposed. Proposed fuzzy logic compensator is used to prevent voltage drop from nonlinear load. The total harmonic distortion (THD) of proposed scheme is better than that of conventional deadbeat control method for linear and nonlinear load. In the third part of this paper, the application of fuzzy control to DC-DC converters operating at finite switching frequency is studied. Several control methods currently used for buck, boost and buck/boost converters are compared to the fuzzy converter control. Simulation results for several control methods are presented. The simulations show that the fuzzy control method has better dynamic performance and less steady state error. 相似文献
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单相H桥级联静止同步补偿器反馈线性化解耦控制 总被引:1,自引:0,他引:1
单相H桥级联静止同步补偿器(static synchronous compemator,STATCOM)n7以快速补偿电力机车这种单相整流的波动性负荷所需的无功,但静止同步补偿器是一个强耦合、非线性系统,为对有功和无功进行解耦,引入反馈线性化方法,通过坐标变化和状态反馈,获得精确线性化模型,并使有功、无功完全解耦,设计... 相似文献
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首先提出根据船舶供电变流器并/离网状态反馈分别进行电流控制、电压控制的模式切换控制方法,实现了离网模式下输出电压快速响应以及并网模式下与电网交互功率的可控转移;其次基于调幅、调频的预同步控制以及电压电流双闭环控制共用比例积分调节器,保证了控制模式切换时积分量的平滑过渡,实现了供电变流器柔性并/离网;然后引入基于多重降阶广义积分器(ROGI)并联的方法实现对输出电压不平衡以及5次和7次谐波的抑制,通过在离散域直接设计ROGI控制参数,避免了数字化过程导致控制器性能偏差;最后搭建了某型船舶直流组网电力推进系统供电变流器的实验平台对所提控制方法的正确性和有效性进行了验证. 相似文献