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Takaaki Kai Nobutaka Takeuchi Tatsunori Sato Hirofumi Akagi 《Electrical Engineering in Japan》1999,129(1):20-28
The thyristor‐controlled series capacitor (TCSC) is promising as a powerful device to increase power transfer capability and transient stability. The basic configuration of the TCSC consists of a series of capacitors connected antiparallel with thyristor‐controlled reactors, so that firing angle control of the thyristors makes the TCSC capable of achieving impedance control in a wide range with quick response. It is important to clarify the relationship between the fundamental reactance of the TCSC and the firing angle of the thyristors, thus leading to practical applications of the TCSC for enhancement of power transfer capability and transient stability in transmission lines. Two relationship equations for the TCSC's fundamental reactance have already been proposed. One is the relationship equation derived from a TCSC circuit whose source is a voltage. The other is the relationship equation derived from a TCSC circuit whose source is a current. For TCSC installed in a transmission line, it is clear which equation is more adequate for analyzing power system stability. In this paper, the authors determine whether either of the equations is valid for analyzing a power system stability.
- 1. In the steady state, the TCSC fundamental reactance is analyzed and compared with the two equations and EMTP. It is clear that the TCSC reactance based on current source is adequate.
- 2. The swing angle of a generator when the firing angle is stepped up is analyzed with EMTP and an analytical model using the TCSC model based on current source. It is shown that the proposed model is effective for power system stability analysis. © 1999 Scripta Technica, Electr Eng Jpn, 129(1): 20–28, 1999
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Thyristor Controlled Series Capacitor (TCSC) as a dynamic system, besides its capability in increasing power transfer in transmission lines, can be used to enhance different power system issues. In this paper, the effect of TCSC on voltage sag following transformer inrush current is investigated. It is shown that excessive transient inrush current occurring during transformer energizing can be mitigated by TCSC. Hence, voltage sag as one of the key components of the power quality is alleviated for the sensitive loads that are connected to the same bus which the power transformer is energized from. During a fault, TCSC can improve the voltage sag by limiting the current and help to keep the voltage as high as possible. Moreover, the inrush currents and the associated voltage sags that usually occur after clearing heavy single- or multistage faults are mitigated by the presence of TCSC. The model used for simulating inrush current is based on the characteristics of the major hysteresis loop out of which the internal trajectories are defined using the translation principal and a linear compensation to generate closed loops. An arctangent relation between the flux and the exciting current is defined. The expression parameters are deduced by curve fitting empirical data defining the major loop or the single-valued saturation characteristic. 相似文献
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为了在1 000 kV特高压输电线路或有较大额定电流的750 kV输电线路上加装可控串补(thyristor controlledseries compensation,TCSC),解决目前TCSC中所需晶闸管阀通流能力不足的问题,提出了一种基于双阀控电抗器(thyristor controlled reactance,TCR)支路并联的TCSC实现方案,并对其控制策略进行了研究。通过对幅值相等控制策略下双TCR支路TCSC进行数学建模,设计了相应的阻抗控制环节和幅值相等控制环节,实现了相应的控制目标。仿真结果表明,提出的TCSC实现方案及其控制策略可行,适用于工程应用。 相似文献
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电网支持型变流器逐渐取代传统同步机电源是构建新型电力系统的必然趋势.电网支持型变流器采用双环控制的目的和物理意义尚未形成统一结论.首先,为解释双环控制中电流内环的本质,由电流内环的离散根轨迹曲线分析电流内环的阻尼特性,从虚拟阻抗的角度分析其物理意义.其次,为快速准确获得双环控制器参数,避免反复迭代,考虑数字控制系统采样... 相似文献
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风电系统接入基于模块化多电平换流器(MMC)的高压直流(HVDC)输电系统是极具前景的输电方案,同时也面临较为突出的系统稳定性问题。小信号阻抗分析法是研究互联系统稳定的有效办法。然而,MMC的内动态特性使得精确建立其阻抗模型具有较大难度。文中采用多谐波线性化方法建立了采用双闭环定交流电压控制的MMC送端换流站小信号阻抗模型,可实现电流环对MMC阻抗影响的准确分析。针对直驱风机通过MMC-HVDC系统并网的系统,利用阻抗分析法分别分析了MMC电流环不同控制带宽下互联系统振荡的问题,为电流环参数优化设计提供了依据。最后,基于MATLAB/Simulink的仿真结果证明了阻抗模型和稳定性分析理论的正确性。 相似文献
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电力系统稳态电流不仅含有基波分量,还包含谐波分量,测量稳态电流各个分量和提高输出信噪比是光学电流互感器(OCT)信号处理的重要环节。本文介绍了基于法拉第磁光效应的OCT的测量原理,针对其低信噪比的特性和电力系统对谐波测量的要求,从时域的角度提出了一种基于线性卡尔曼滤波结合锁相环技术的谐波电流测量方法。在被测电流信号为基波电流、谐波电流和白噪声的混合信号的情况下,建立了线性的测量模型。在Lab VIEW上进行测量验证,结果表明卡尔曼滤波结合锁相环方法在测量稳态电流各个分量的同时能够有效地提高OCT输出信噪比和测量精度。 相似文献
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针对电网电压谐波背景下虚拟同步发电机(VSG)并网电流畸变及并网稳定性下降问题,文中提出了一种基于电流环的电网电压前馈控制策略。从入网电流传递函数出发,设计电压前馈控制模块以消除背景谐波的影响,并基于谐波线性化方法分别建立加入前馈控制前后的VSG序阻抗模型,对其在各频段阻抗特性及并网稳定性上的影响进行对比分析。结果表明,引入该前馈控制等同于在VSG输出端并联虚拟阻抗,输出阻抗的高频段幅频曲线上移,可以改善非理想电网条件下的并网电流质量。同时,中高频段相频特性由容性矫正为感性,可以消除并网条件下的谐波振荡风险,提高交互系统稳定性。最后,基于实时仿真实验平台(RT-LAB)硬件在环实验验证了文中控制策略及理论分析的正确性。 相似文献
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Mansoor A. Grady W.M. Chowdhury A.H. Samotyi M.J. 《Power Delivery, IEEE Transactions on》1995,10(1):467-473
Widely distributed single-phase power electronic loads are an increasingly important source of harmonics in power distribution systems. The objective of this paper is to investigate the cumulative harmonic current characteristics of a large number of such loads. A complete analytical model for the most common load type is derived. This model is then used to investigate the impact of: (1) interaction due to a shared source impedance; (2) variation in power level; and (3) variations in circuit parameters, on individual and cumulative current harmonics. The key findings of the paper are that diversity and attenuation are very important factors in predicting the behavior of distributed single-phase power electronic loads, especially for the higher-order harmonics, and that due to these two factors, the commonly-used fixed current injection method, using arithmetic sums of harmonic current magnitudes, can significantly overestimate the cumulative harmonic currents produced by these loads 相似文献
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TCSC抑制次同步谐振的机理研究及其参数设计 总被引:37,自引:6,他引:37
正确地分析TCSC频率阻抗特性是评价TCSC抑制SSR能力的基础。该文给出了考虑导通角变化的三维频率阻抗图,该图清晰地表明:当目标导通角小于临界导通角时,TCSC低频阻抗特性存在一个容性曲面,只有越过临界导通角后低频视在阻抗才表现为感性。基于IEEE第一基准模型的数字仿真分析验证了频率阻抗计算方法和结果的正确性,深入阐明了TCSC抑制SSR的物理机理以及要实现完全抑制SSR需满足的工作条件。在此基础上还讨论了TCSC主电路的参数设计原则,使得TCSC不仅能满足工频基波阻抗调节特性的要求,而且能最大限度地提高对SSR的抑制能力。 相似文献
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Toshihisa Shimizu Tsutomu Fujita Gunji Kimura Jun Hirose 《Electrical Engineering in Japan》1998,123(1):51-62
The generation of harmonics and their subsequent propagation into power lines is a topic of increasing concern to power-supply authorities. To prevent obstacles in the power system, a unity-power-factor PWM converter will be applied at ac-dc power conversion plants. However, the PWM converter, especially at single-phase circuit, has some serious defects, including low-frequency ripple current that flows into the dc line and gives rise to a low-frequency ripple voltage that appears on the dc output. In usual cases, it is necessary to connect a very large capacitor or a passive L-C resonant circuit to the dc line for reduction of low-frequency ripple voltage. However, when batteries are connected to the dc output, most of the dc ripple current flows into the battery even if the above circuits are used, because the impedance of the battery is very low compared to that of the circuits. The low-frequency ripple current causes power loss on the battery and the temperature rises. It is well known that the life of a battery is deeply influenced by the temperature. The ripple current, therefore, should be reduced as low as possible. To accomplish reduction of the low-frequency ripple current, a novel topology for the PWM rectifier is presented in this paper. The main circuit is constituted by adding only a pair of switching devices to the conventional PWM converter circuit. With a simple control technique, the ripple energy on the dc line is converted into stored energy on the input ac capacitors through additional switches. The theoretical characteristics are obtained by using the state-space averaging method. The effect of ripple reduction is confirmed by experiments using a breadboard setup. © 1998 Scripta Technica, Electr Eng Jpn, 123(1): 51–62, 1998 相似文献
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柔性直流输电稳定性分析及控制参数整定 总被引:1,自引:0,他引:1
针对柔性直流输电的特点,将其稳定性分析分为两部分,即柔直系统直流侧稳定性分析和交直流互联的稳定性分析。对于直流侧的稳定性分析,首先建立柔直系统的简化复频域电路,然后得到等效环路增益,采用Middlebrook判据进行稳定性判断;对于柔直系统与交流互联网络,首先探讨其稳定性机理,然后通过dq旋转坐标系下的电流环控制结构框图构建换流站的等效电路,并推导出换流站的等效导纳表达式,最后通过注入非特征谐波电流法进行交流侧阻抗检测,利用交直流阻抗比的频域特性进行稳定性判断,找出稳定的控制参数域。利用PSCAD/EMTDC软件对实际工程中不同等效场景下交流侧阻抗对稳定性的影响进行仿真,证明了采用所提方法进行稳定性判断及控制参数整定的有效性。 相似文献
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TCSC对抑制次同步谐振的机理分析 总被引:15,自引:7,他引:8
对具有可控串联电容补偿的电力系统,提出了一种直接计算可控串补对次同步频率 分量所反映出的等值阻抗的算法。基于该计算原理,对可控串补具有正等值电阻这一特性给 出了详细的机理解释。 相似文献