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A novel approach to compensating for harmonics in power systems is presented. It is a combined system of a shunt passive filter and a small rated series active filter. The compensation principle is described, and some filtering characteristics are discussed in detail. Excellent practicability and validity to compensate for harmonics in power systems are demonstrated experimentally. Although the source harmonic voltage was only 1%, the source harmonic current reached about 10% before the series active filter was started. After it was started, no harmonic current flowed into the shunt passive filter. In addition, no harmonic voltage appeared at the terminals of the shunt passive filter, because the source harmonic voltage was applied to the series active filter. The total loss of the series active filter was less than 40 W. It is concluded that the combined system is far superior in efficiency to conventional shunt active filters 相似文献
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并联有源滤波器在消除谐波电流和无功补偿(包括线性负载和非线性负载的无功补偿)方面发挥着重要的作用。目前,电力有源滤波器(APF)多采用基于瞬时无功功率理论的谐波和无功电流检测方法。这些方法大多要进行坐标之间的转换,并且在三相电路、电源都不对称的情况下很难做到对基波无功和高次谐波电流的准确检测。提出一种不需要在进行坐标转换,直接在坐标系下进行无功和谐波检测的方法。研究和仿真表明这种方法在电压源不对称、畸变和负载不平衡的情况下仍能有效工作,并且有效简化了并联有源滤波器(APF)的控制电路。 相似文献
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Cheng-Che Chen Yuan-Yih Hsu 《Power Delivery, IEEE Transactions on》2000,15(4):1258-1264
A new approach is presented for the design of a shunt active filter in a three-phase, four-wire distribution system with unbalanced, distorted sources and unbalanced loads. The purpose of the shunt active filter is to provide compensation currents such that the source needs to supply balanced (positive-sequence) fundamental source current at unity power factor even though the load consumes harmonic currents as well as positive, negative, and zero-sequence currents. A major feature of the proposed approach is that it does not require symmetrical component transformation to transform the three-phase voltages and currents to α-β-o quantities. This makes practical implementation of the proposed method easier than the symmetrical component transformation approach. In addition, the power factor of the positive-sequence fundamental component is close to unity and only positive-sequence power is supplied by the source. The effectiveness of the proposed control algorithm is demonstrated by computer simulation and experimental results of a shunt active filter for a three-phase four-wire distribution system with distorted, unbalanced source voltages and unbalanced loads 相似文献
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The Institute of Electrical and Electronic Engineers (IEEE) ‘Recommended Practices and Requirements for Harmonic Control in Electric Power Systems’ sets limits for the current and voltage harmonic distortions at the point of common coupling in order to maintain an acceptable quality of electric power in the presence of nonlinear loads. Both the utility and its customers share a common responsibility since enforcement of the above practice by the utility would require that the affected customer use a suitable harmonic mitigating method. To this effect, this paper demonstrates how the Electromagnetic Transients Program (EMTP) may be used to investigate two harmonic mitigating methods, namely, the use of shunt passive power filters and the combination of a series active (APF) and shunt passive (PPF) power filters. Both methods reduce the harmonic currents injected into the distribution system; however, the combination of the series APF and shunt PPFs has a better compensation characteristic with a higher capital cost than only shunt PPFs. Before a final decision is reached, the cost of the higher harmonic losses throughout the distribution system when using only shunt PPFs must be taken into account. 相似文献
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针对有源电力滤波器无法动态补偿无功功率,无源滤波器补偿产生相移的问题,提出一种晶闸管控制电抗器与并联混合电力滤波器(SHPF-TCR)联合补偿控制系统。SHPF由小容量有源电力滤波器和五次LC单调谐滤波器构成以补偿系统谐波,调谐滤波器和TCR形成并联型无源滤波器以补偿系统无功。将解耦控制用于电流跟踪和电压调节,引入PI控制器消除系统稳态误差。该SHPF-TCR联合控制能够有效的降低APF容量,消除系统谐振,稳定性好,动态响应速度快。实验及仿真结果证明了所提出结构和控制方法可以很好地进行谐波和无功的综合补偿。 相似文献
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Fang Zheng Peng 《Industry Applications Magazine, IEEE》1998,4(5):21-30
In this article, common nonlinear loads have been characterized into two types of harmonic sources, current-source type of harmonic source and voltage-source type of harmonic source. Compensation characteristics of both parallel active filters and series active filters have been discussed analytically and experimentally for these two types of harmonic sources. The corresponding required operation conditions, features, application issues, and adaptive harmonic sources of both filters have been presented. The fact that the traditional active filter, the parallel active filter, is not a panacea to harmonic compensation, and that one cannot use it blindly, has been clearly addressed. The parallel active filter will increase harmonic current and may cause overcurrent of the load when the load is a harmonic voltage source. Instead, it has been verified that the series active filter is better suited for compensation of a harmonic voltage source such as a diode rectifier with smoothing DC capacitor. The conclusions of this article also imply that when a parallel active filter is installed in a power system network such as at a point of common coupling, the network impedance and main harmonic sources downstream from the installation point should be investigated in order to get good performance and to minimize influence to the loads downstream. In some cases, a combined system of parallel active filter and series active filter may be necessary by utilizing the harmonic isolation function of the series active filters. No doubt active filters are superior to passive filters if used in their niche applications 相似文献
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This paper focuses on a shunt active filter based on the detection of harmonic voltages at the point of installation. The objective of the active filter is to attenuate harmonic propagation resulting from series/parallel resonance between capacitors for power factor correction and line inductors in a power distribution line. The active filter acts as a low resistor to the external circuit for harmonic frequencies, and it is installed on the end bus of the power distribution line, just like a 50 Ω terminator installed on the end terminal of a signal transmission line. Therefore, the function of the active filter is referred to as “harmonic termination” in this paper. Experimental results obtained from a laboratory system rated at 200 V and 20 kW verify that the active filter for the purpose of harmonic termination has the capability of harmonic damping throughout the power distribution line 相似文献
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提出一种利用低漏抗变压器和并联型低压有源电力滤波器实现对高电压等级补偿的新方法。针对现场工况情况,考虑到变压器的移相特性,采用一种新型数字锁相环技术对原有控制策略进行改进,实现了通过低压有源滤波器对高电压母线的谐波治理和无功补偿。在不改变低压有源滤波器内部结构的前提下,可以替代高压有源电力滤波器完成补偿任务,降低设备投资。低压有源滤波器电压等级较低,可以降低设备运维难度,并能提高运维人员的安全系数。通过PSCAD/EMTDC数字仿真和现场实物试验,验证了相关设计的有效性和可行性。 相似文献
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Active power filters have been used in practice to suppress the harmonic interference in power systems. To compensate for harmonic currents of loads, active power filters usually are connected to power systems in parallel with the loads. These filters, which are called shunt active filters here, are very effective for loads that can be considered as current sources, such as thyristor rectifiers with large dc reactances. Many papers have covered the shunt active filters applied to these current-source loads, however, none has discussed characteristics of the shunt active filters when they are applied to voltage-source loads. On the other hand, since more and more diode rectifiers with capacitive dc filters have recently been used, harmonics generated by them have become an issue. The diode rectifier with capacitive dc filters behaves as a voltage source rather than a current source. When a shunt active filter is applied to such a diode rectifier, the current injected from the shunt active filter may flow into the diode rectifier. As a result, harmonics of the source current cannot be reduced effectively, and harmonic current flowing into the diode rectifier increases greatly. This paper presents the aforementioned problem of shunt active filters analytically and experimentally. Then a series active filter is proposed to suppress the harmonic current of the diode rectifiers. The features, operating conditions, and considerations of shunt active filters and series active filters are described analytically and demonstrated experimentally. Taking a diode rectifier with capacitive dc filter as a typical voltage-source load, compensation characteristics of shunt active filters and series active filters are discussed by experiment and simulation. The validity of the series active filters is illustrated experimentally. 相似文献
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This paper deals with grid synchronization and control of single-phase voltage source inverter in distributed generation (DG) systems using a multi-output adaptive filter. Besides the active power injection, the proposed control enables the inverter to compensate load harmonic and reactive currents based on the capacity of inverter. The currents to be compensated are obtained using a multi-output adaptive filter structure that operates on the principle of variable step size (VSS) least mean squares (LMS) algorithm. The main objective of VSS-LMS filter is to decompose the load current into harmonic and reactive current components and compute their RMS values. The currents extracted by the VSS-LMS filter are used in developing a flexible compensation based on load compensation factors. The load compensation factors are calculated based on the remaining capacity of the inverter and priority. Harmonic currents compensation is given first priority over the reactive currents. In addition to harmonic currents detection, the same VSS-LMS filter is used in developing a phase locked loop unit for synchronizing the inverter with fundamental point of common coupling (PCC) voltage. Synchronizing the DG inverter with fundamental PCC voltage would make the proposed control algorithm insensitive to grid voltage harmonics and frequency fluctuations. The feasibility and the efficacy of the proposed control algorithm are demonstrated using hardware-in-the-loop (HIL) based experiments. 相似文献
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电动汽车充电站并联有源滤波器工作时,可能引起流过充电站集电母线的充电电流谐波出现放大效应。针对谐波污染最严重的三相不可控整流充电机,研究充电站各次谐波电流与谐波电压的耦合关系,定义电动汽车充电站总谐波电流放大系数,提出一种充电站集电母线电流谐波放大程度的量化方法。该方法实现了电流谐波放大效应的解析计算且具有较高精度。在此基础上,探讨谐波放大系数随充电机台数、有源滤波补偿率及相位差等因素的变化规律,为有源滤波器容量配置与控制设计提供依据。 相似文献
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Hugo Ramos‐Carranza Aurelio Medina 《International Journal of Circuit Theory and Applications》2013,41(5):457-482
In this contribution, a steady‐state approach for determining the optimal size and control of a shunt hybrid filter (SHF), to control harmonic current mitigation and to provide reactive power compensation, is proposed. The SHF topology is formed by a shunt active power filter (APF) and a shunt capacitor. The APF current injections are determined from the solution of a nonlinear programming problem formulated to meet permissible operation limits, with an optimal APF size. The formulation and control theory for the SHF is developed in the abc reference frame. An important practical aspect such as the application of SHF compensation in non‐stiff systems is included in the analysis and solution of the nonlinear programming problem, as well as in the current control technique, maintaining stringent performance requirements on the tracking of the filtering currents, by allowing the use of the shunt capacitor also as a filter for draining the ripple current inherent to the APF injection currents. Results obtained with matlab /Simulink (MathWorks, Inc., Natick, MA, USA) show that the proposed theory and the control of the optimal SHF compensation constitute an effective system to compensate reactive power and to control harmonic distortion under selected/permissible limits with an optimal APF injection current reducing the APF size. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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基于有功能量平衡原理的并联型有源滤波器的控制方法 总被引:8,自引:0,他引:8
介绍了一种基于有功能量平衡原理的并联型有源滤波器的控制方法。首先分析了并联型有源滤波器在补偿阻感负载时,瞬时有功和瞬时无功在系统中的传递过程。接着从有功能量平衡原理的角度,提出了通过对直流侧电压反馈进行PI调节,来获得整个系统所需的输入有功分量方法。这种方法无需复杂谐波检测,只需检测两路电源电流信号和一路电压信号,从而使整个控制系统得以简化。最后通过仿真和实验对提出的方法进行了验证,实验表明这种方法具有较好的谐波补偿效果。 相似文献
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The combined system of a series active filter and a shunt passive filter that is proposed by the authors has the ability to eliminate a major disadvantage of shunt passive filters, namely, harmonic amplification. The series active filter needs a much smaller kVA rating than a conventional shunt active filter, and as a result, the combined system has good filtering characteristics and high efficiency. This paper presents an optimum design of the shunt passive filter that makes possible a great reduction in the required kVA rating of the series active filter. It can minimize the peak voltage across the series active filter and reduce the required kVA rating of the filter to 60 percent. A computer simulation geared to practical applications of large three-phase. twelve-pulse thyristor rectifiers is used to compare the compensation characteristics of the optimized system with those of a combined system that uses a conventional shunt passive filter. Experimental results obtained with a laboratory model of the filter corroborate the design approach. 相似文献
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