共查询到20条相似文献,搜索用时 781 毫秒
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与传统两电平静止同步补偿器相比,多电平静止同步补偿器由于具有电压等级和装置容量高、输出波形质量好等优点在高压大功率场合得到了广泛的应用。本文首先对三电平STATCOM(静止同步补偿器)的工作原理和运行特性进行了阐述,接着针对阻感负载提出了一种基于序分解的三电平STATCOM不平衡控制策略,并在电网电压不平衡以及负载不对... 相似文献
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针对电网运行电压不稳定的情况,采用静止同步补偿器(STATCOM)对电网进行无功功率补偿以稳定运行电压。文中给出了运行电压和无功功率的关系,阐述了STATCOM的基本结构与工作原理,分析了STATCOM的控制方法及策略。并根据工作原理和控制方法,在Matlab环境下搭建了基于δ和λ的双控制变量STATCOM模型。仿真结果表明,STATCOM可精确、快速地补偿电网所需无功功率,达到了稳定运行电压的目的。 相似文献
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多电平变换器以其输出电能质量高、谐波失真小、电磁干扰小等优点受到了广泛的关注。然而,现有多电平逆变器存在器件数量较多和电压应力较大等缺点。对此,提出一种新型简易级联式多电平逆变器拓扑结构。首先,介绍了逆变器的拓扑结构,讨论了变换器的对称和非对称形式。然后,将该拓扑结构与级联H桥变换器进行了比较分析。结果显示,该拓扑结构减少了开关数量和门驱动器数量。同时,该拓扑的峰值反向电压低于传统CHB变换器。此外,模块化是该拓扑的另一个重要特征。最后搭建一台样机进行实验,证明了所提出电路的有效性和可行性。 相似文献
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提出了一种基于电网电压补偿的多电平变频器控制方法,从主回路拓扑结构出发,以低压变频器规则采样法为基本理论,详细介绍了适合于多电平变频器控制的理论分析和算法推导过程。并给出了适合数字信号处理的采样原理和采样时序。直接根据电网电压的变化,实时调节输出电压,能获得与闭环系统相媲美的理想机械特性和运行效果。该方法不仅具有计算步骤简单、输出SPWM对称性好、精度高和控制方便的特点,而且适用于任何电平数目及拓扑结构。试验结果表明,和其他多电平控制方法相比,使用效果好,有很高的利用价值。 相似文献
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文中给出了一种解决最优无功潮流的应用程序来控制STATCOM无功功率的输入。通常情况下,一个无功功率补偿器,例如STATCOM,可以由不同的方式来控制。它是一个优化程序,当同时满足所有系统的约束时,在这个程序中特定的目标将最小化。最优无功功率的解决方案是用来设定为STATCOM控制器的参照。为了证明该控制方法,一个简单的three-bus测试系统的24 h最优潮流计算被用来做测试。结果表明,采用最优无功潮流计算的无功功率补偿有利于将整个电力系统操作的损失最小化,同时系统电压是稳定的。 相似文献
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Simple Unified Approach to Develop a Time-Domain Modulation Strategy for Single-Phase Multilevel Converters 总被引:1,自引:0,他引:1
《Industrial Electronics, IEEE Transactions on》2008,55(9):3239-3248
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传统的交流型并网发电系统中,可以通过检测电网电压或频率,采用有功扰动、无功扰动或频率扰动等方法实现防孤岛控制。而在共直流母线系统中,母线直流电压是唯一可检测的变量,因此传统的防孤岛控制策略无法适用。以共直流母线分布式系统中光伏直流模块的防孤岛控制为研究对象,建立了模块正常运行和孤岛运行时的数学模型,推导得到了在两种工况下模块输出电压的时域表达式,并在此基础上提出了一种基于注入电流扰动法的新型防孤岛控制策略。该控制策略的核心思路是通过控制模块输出电流和扰动步长来改变在扰动时间内模块的输出电压特性,并根据检测判据来决策是否发生孤岛。最后,本文以Boost+FB-LLC的两级式结构作为光伏直流模块的工作拓扑,并设计了一台1000W的实验样机,样机实验结果验证了本文所提出的防孤岛控制策略的有效性。 相似文献
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Qi Wang Jianfeng Dai Quanchun Yan Lixin Fan Yi Tang 《International Journal of Electronics》2020,107(2):250-271
ABSTRACTVoltage violation is an important factor that restricts grid-connected photovoltaic system. The utilization of PV plant’s reactive power capability is an effective measure to mitigate voltage violation. This paper proposes two-stage voltage control strategy to enhance the voltage support capability of photovoltaic grid-connected system. In first stage, adaptive gains are set according to the maximum reactive capacity of each PV plant in order to distribute reactive power among PV plants more reasonably, avoiding certain PV plants operating in the limit state for a long time. In second stage, when the reactive power capacity is insufficient, the priority of active power curtailment for each PV plant is calculated in real time. Active power curtailment control will be performed in PV plants with high priority to released more reactive power capacity for voltage support. The simulation results carried out by PSCAD/EMTDC software demonstrated that this strategy can effectively solve the voltage violation problem. Meanwhile, the proposed strategy not only can exploit reactive capacity of each PV plant as much as possible to avoid certain PV plants operating in the limit state for a long time, but also can reduce the amount of active power curtailment when reactive power adequacy is insufficient. 相似文献
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This paper introduces new controls for the cascaded multilevel power converter. This converter is also sometimes referred to as a ldquohybrid converterrdquo since it splits high-voltage/low-frequency and low-voltage/pulsewidth-modulation (PWM)-frequency power production between ldquobulkrdquo and ldquoconditioningrdquo converters respectively. Cascaded multilevel converters achieve higher power quality with a given switch count when compared to traditional multilevel converters. This is a particularly favorable option for high power and high performance applications such as naval ship propulsion. This paper first presents a new control method for the topology using three-level bulk and conditioning inverters connected in series through a three-phase load. This control avoids PWM frequency switching in the bulk inverter. The conditioning inverter uses a capacitor source and its control is based on compensating the real and reactive (P-Q) power difference between the bulk inverter and the load. The new control explicitly commands power into the conditioning inverter so that its capacitor voltage remains constant. A unique space vector analysis of hybrid converter modulation is introduced to quantitatively determine operating limitations. The conclusion is then generalized for all types of controls of the hybrid multilevel converters (involving three-level converter cells). The proposed control methods and analytical conclusions are verified by simulation and laboratory measurements. 相似文献
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本文提出一种光伏并网发电与有源电力滤波器的统一控制策略,新的系统结构和控制策略在实现光伏并网发电的同时,也能对系统进行无功及谐波补偿,实现一机多能,通过整合资源,降低成本,推动APF和光伏发电技术的共同发展。文中对APF和光伏并网的统一控制原理、新系统结构的演变、系统工作原理和控制策略等进行了详细的分析研究,利用MATLAB/Simulink对提出的APF和光伏发电统一控制系统进行了仿真验证,仿真结果验证了提出的系统结构及控制策略的可行性和正确性。 相似文献
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Escalante M.F. Vannier J.-C. Arzande A. 《Industrial Electronics, IEEE Transactions on》2002,49(4):809-815
In this paper, the requirements imposed by a direct torque control (DTC) strategy on multilevel inverters are analyzed. A control strategy is proposed in order to fulfill those requirements when a flying-capacitor multilevel inverter is used. Simulation and practical results will confirm the performance of the proposed strategy when using the multilevel inverter to control an induction motor by the DTC principle. Also, the advantages of using a multilevel inverter with a DTC strategy are shown by simulation results. 相似文献
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级联型多电平逆变器由于其模块化结构、便于生产高度、更换容易等特点,受到电力电子工程技术人员的广泛关注。本文通过对于级联型多电平逆变器几种典型的控制方法的分析比较,提出了一种改进多载波PWM控制方法。该方法通过改变载波的幅值,使级联逆变器的各个逆变单元开关规律相同,并使所有的开关器件的损耗一致,有利于逆变单元的统一设计和可靠运行。 相似文献
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随着用电需求的增大,电网中感性用电设备对无功功率的需求日益增大,被消耗的无功若得不到及时补偿,将严重影响电网的运行效率。为此,本文以模糊PID参数自整定为控制策略,设计了基于ARM无功补偿控制器,将传统的PID控制和模糊控制相结合,通过模糊推理来达到PID参数自调整的目的。设计采用实时多任务、可移植的嵌入式μC/OS—Ⅱ操作系统,以32位RISC微处理器s3C2440为控制中心,采用RS-485完成于上位机之间的信息传输。该控制系统控制精度高,设计更为简单,易于实现,达到了预期目标,具有很好地应用前景。 相似文献