Advanced SVC control for damping power system oscillations

A new SVC (static VAR compensation) control for damping of power system oscillations has been developed. To increase system damping an SVC uses a phase angle signal estimated from the measurement of voltage and power at the SVC location. By means of an optimization and identification procedure, optimized design of the damping control with various control concepts can be determined, taking into account nonlinear power systems. As a result of this method it is possible to increase power system damping considerably, in particular in critical situations close to the stability limit, using only locally measured state variables at the SVC, thus leading to an increase in the transmission capability of the power system     

电力系统阻尼控制机理与特性

基于单机-无穷大电力系统,采用等面积定则分析电力系统阻尼控制机理。对电力系统稳定器（PSS）、静止无功补偿器（SVC）、晶闸管控制的串联电容器（TCSC）和高压直流（HVDC）的附加阻尼控制器的运行特性进行总结。对如何利用电网中各种阻尼资源以提高抑制系统区间振荡的能力进行讨论。当系统中已安装的PSS不能有效阻尼区间振荡时,可优先考虑利用HVDC的附加阻尼调制来增强阻尼。此外,可考虑柔性交流输电系统（FACTS）的附加阻尼控制,并认为TCSC抑制区间振荡的效果一般优于SVC。在四机两区域电力系统中的仿真分析结果验证了结论的合理性。     

Application of static VAr compensators to increase power systemdamping

A theory for analyzing power system damping enhancement by application of static VAr compensators (SVCs) has been developed using the equal area criterion. Some fundamental issues, such as the effect of SVCs on a power system, how to control an SVC to improve system damping, and the differences between continuous and discontinuous control of SVC reactive power to achieve the maximum damping improvement, are discussed. A discontinuous SVC reactive power output at discrete points is determined from the power deviation on a transmission line. Time-domain simulations of the application of this approach to a one-machine system to increase swing oscillation damping and to a four-machine system to increase the damping of an interarea oscillation mode demonstrate that the theory and method can be applied to solve practical power system damping problems     

静止无功补偿器阻尼电力系统振荡（上）——理论分析

本文建立了装有静止无功补偿器（ＳＶＣ）的电力系统的推广Ｐｈｉｌｌｉｐｓ－Ｈｅｆｆｒｏｎ模型。在此基础上，从理论上分析了利用静止无功补偿器阻尼电力系统振荡研究中的基本问题，即：ＳＶＣ能够向电力系统提供正阻尼，提高电力系统静态稳定性的条件；电力系统参数，运行工况，ＳＶＣ电压控制及阻尼控制强度对ＳＶＣ向电力系统提供阻尼能力的影响；ＳＶＣ阻尼控制最佳安装地点的选择。文中首次提出了ＳＶＣ阻尼控制存在“失灵点”的概念，并分析了“失灵点”存在的原因。本文下篇中给出的研究实例，其特征值分析和非线性仿真的结果验证了文中给出的分析结论。     

Enhancement of power system dynamic performance through an on-line self-tuning adaptive SVC controller

Static VAr compensators (SVC) are used for voltage control of long distance bulk power transmission lines. By using a supplemental control loop an SVC can also be used to improve the dynamic and transient stability of a power system. Use of a self-tuning adaptive control algorithm as a supplementary controller for the SVC is presented in this article. The control derived is based on a pole-shifting technique employing a predicted plant model. Simulation studies on a simple power system model showed rapid convergence of the estimated plant parameters with an extremely good damping profile. The controller has been tested for ranges of operating conditions and for various disturbances. The effectiveness of the adaptive damping controller was also evaluated through an ‘optimized’ PI controller.     

静止无功补偿装置的实用化技术与措施

静止无功补偿装置(SVC)是柔性交流输电控制装置的重要内容之一,具有动态平滑的调节特性及向电力系统提供阻尼的作用。介绍了SVC实用化技术,如进行自动电压控制(AVC),预防电网电压失稳,提高电网的输送能力,防止事故扩大,紧急情况下可以形成有效的反电压崩溃防线,在冶金、电气化铁路等行业治理电压波动、闪变、谐波污染并平衡随时间变化的非对称负荷,防止发生次同步谐振,给直流输电提供无功等在提升电力系统安全优质经济运行水平中的作用。简要介绍了SVC国产化的现状,并提出了推行SVC的具体建议。     

Fuzzy bang-bang control of static VAR compensators for damping system-wide low-frequency oscillations

Static VAR compensators (SVCs) have been widely used in power systems to keep terminal voltages within bounds. The other application is to improve power systems damping, especially for loosely connected power systems. In this paper, a scheme using fuzzy logic control (FLC) is connected in parallel with a conventional voltage regulation loop to form a supplementary damping loop for the SVC to increase the system's transmission capacity. The FLC is based on bang-bang control, and provides damping across each connected line to the SVC. Damping is of particular importance especially for weakly coupled power systems. Using rotor-angle signals that are estimated from voltage and power measurements at each connected line to the SVC, a fictitious generator at the remote end of each connected line is identified. The SVC receives control signals from all fictitious generators, which are competing and reacting differently at different phases of system oscillations. The final control for the SVC combines the control signals from all fictitious generators, which are scaled according to their individual contributions to damping. The proposed signal structure guarantees robustness and effectiveness of the final control with respect to different loading and fault conditions. The FLC design is based on Lyapunov function analysis, and is simulated on a three-generator power system for performance evaluation.     

SVC电压控制与阻尼调节间相互作用机理研究

通过对含静止无功补偿器(static var compensator,SVC)的单机无穷大(single machine infinite-bus,SIMB)系统进行电磁转矩计算,从理论上分析SVC的电压控制和阻尼调节之间的相互作用关系,既要保证同时为系统提供正的同步转矩和阻尼转矩,电压控制增益和阻尼控制增益的取值需满足一定的限制关系。通过对PSASP中36节点系统进行特征值分析,从广义阻尼的角度分析SVC控制参数对系统阻尼的影响。分析结果表明,电压控制增益和时间常数可改变系统的总阻尼,阻尼控制增益只能对系统的阻尼特性进行重新配置,从而改善系统的弱阻尼区间振荡模式。仿真验证了上述结论的有效性。     

静止无功补偿器对电力系统性能改善的综述

随着电力电子技术、微处理技术和控制技术的发展,柔性交流输电系统FACTS(Flexible AC Transmission System)的出现,为电力系统急待解决问题提供了新的手段或策略。静止无功补偿器(SVC)作为FACTS家族的成员之一,对电力系统性能的改善也已取得了可喜的成绩。因此,从静止无功补偿器提高稳态输送容量、提高暂态稳定性、增强系统阻尼抑制低频振荡、缓解次同步谐振、预防电压不稳定或控制电压的波动、改善直流输电系统的性能等六个方面进行综述。     

基于最优变目标策略的励磁系统与SVC协调控制

发电机励磁系统以及静止无功补偿器(SVC)对远距离输电系统的稳定性有很大影响。文章基于单机无穷大系统的非线性模型,建立了包括状态变量发电机机端电压在内的状态空间方程,提出了一种最优变目标控制(OVAC)策略,根据励磁系统和SVC不同的控制目标分别采用不同的控制策略,从而协调控制这两种控制器。仿真结果表明,该策略能够有效提高故障时发电机的无功出力,并能提高系统阻尼,抑制振荡,同时改善系统的功角和电压稳定性。     

Optimal placement and parameter setting of SVC and TCSC using PSO to mitigate small signal stability problem

This paper aims to select the optimal location and setting parameters of SVC (Static Var Compensator) and TCSC (Thyristor Controlled Series Compensator) controllers using PSO (Particle Swarm Optimization) to mitigate small signal oscillations in a multimachine power system. Though Power System Stabilizers (PSSs) associated with generators are mandatory requirements for damping of oscillations in the power system, its performance still gets affected by changes in network configurations, load variations, etc. Hence installations of FACTS devices have been suggested in this paper to achieve appreciable damping of system oscillations. However the performance of FACTS devices highly depends upon its parameters and suitable location in the power network. In this paper the PSO based technique is used to investigate this problem in order to improve the small signal stability. An attempt has also been made to compare the performance of the TCSC controller with SVC in mitigating the small signal stability problem. To show the validity of the proposed techniques, simulations are carried out in a multimachine system for two common contingencies, e.g., load increase and transmission line outage. The results of small signal stability analysis have been represented employing eigenvalue as well as time domain response. It has been observed that the TCSC controller is more effective than SVC even during higher loading in mitigating the small signal stability problem.     

四种FACTS装置对改善风光互补系统稳定性的研究

新能源的接入对电力系统稳定性的影响越来越大。FACTS装置在工频下快速调节系统基波潮流来提高系统输送能力和稳定性。对4种典型FACTS装置接入风光互补系统的原理和动态特性进行比较研究, 同时考虑互联系统联络线传送功率、风光互补系统出力等工况影响,设计了附加功率振荡阻尼控制器,通过反馈控制来调节装置可控的系统电气参量,起到阻尼低频振荡的作用。最后,针对算例系统进行了仿真计算,结果表明:UPFC和STATCOM在提高系统机电振荡模式阻尼比、抑制系统低频振荡方面性能优于SVC和TCSC,特别在其并联侧附加阻尼控制器后,能明显降低系统振荡幅度,提高系统稳定性。     

静止无功补偿器在川渝电网500 kV单相瞬时对地短路试验中的控制效果

论述了应用于500 kV川渝输电系统的静止无功补偿器的控制调节策略,对川渝电网500 kV人工单相瞬时接地短路试验中静止无功补偿器的动态响应行为进行了描述,通过超高压远距离输电网大扰动试验验证了静止无功补偿器对稳定川渝500 kV系统电压、阻尼潮流断面有功功率振荡、提高川渝电网系统的暂态稳定性等实际作用。     

A novel SVC supplementary controller based on wide area signals

Static Var Compensator (SVC) is a kind of FACTS device which is used in power system primarily for the purpose of voltage and reactive power control. Based on wide area signals, this paper presents a systematic approach for designing SVC supplementary controller, which is used to improve the damping of power system oscillation. The principle for damping oscillation by SVC is first analyzed and the concept of synthetic residue index is then presented which is used to choose the proper input wide area signals. Parameters of the controller are determined by means of test signal method and residue root locus. Eigenvalue analysis and time domain simulations are performed on a two-area system and the results demonstrate the effectiveness of the proposed controller.     

Damping controller design for power system oscillations usingglobal signals

This paper describes a new power system stabilizer (PSS) design for damping power system oscillations focusing on interarea modes. The input to the PSS consists of two signals. The first signal is mainly to damp the local mode in the area where PSS is located using the generator rotor speed as an input signal. The second is an additional global signal for damping interarea modes. Two global signals are suggested; the tie-line active power and speed difference signals. The choice of PSS location, input signals and tuning is based on modal analysis and frequency response information. These two signals can also be used to enhance damping of interarea modes using SVC located in the middle of the transmission circuit connecting the two oscillating groups. The effectiveness and robustness of the new design are tested on a 19-generator system having characteristics and structure similar to the Western North American grid     

TSC型静止无功补偿器提高系统阻尼特性的研究

长距离大功率输电系统，在暂态时阻尼特性较差是其稳定性的主要特点。本文从理论上论证了静止无功补偿器（ＳＶＣ）能够提高系统阻尼特性的原理，证明了ＳＶＣ采用频率作为控制信号时具有最佳的阻尼效果，给出了ＳＶＣ模型。实际５００ｋＶ长距离输电系统仿真计算所得的结果验证了ＳＶＣ提高系统阻尼特性的效果。     

Application of static VAr compensators for the dynamic performanceof the Mead-Adelanto and Mead-Phoenix transmission projects

This paper presents the planning and pre-specification study analysis and results for the joint use of static VAr compensators (SVC), a form of flexible alternating current transmission system (FACTS) technology, for the Mead-Adelanto and Mead-Phoenix projects in the Southwestern USA. Because of insufficient system damping in the network, addition of these two transmission line projects must also be complemented by SVC. These devices increase the system stability limit so that the projects' planned transfer capabilities can be economically attained. These are the first transmission projects in the region where a very closely coordinated planning effort permits the joint use of SVC to provide mutual benefits to both projects. SVC dynamic performance enhancement studies, SVC control analysis, and studies related to the planning and specification requirements are among the topics addressed in the paper     

Tuning a static var compensator controller over a wide range of load models using an artificial neural network

A novel approach using an artificial neural network (ANN) for tuning a static var compensator (SVC) controller over a wide range of load models is presented in this paper. To enhance power system damping over a wide range of load models, it is desirable to adapt the SVC controller gain in real time based on load models. To do this, online measurements of load parameters which are representative of load models are chosen as the input signals to the neural network. The output of the neural network is the desired gain of the SVC controller. The neural network, once trained by a set of input-output patterns in the training set, can yield a proper SVC controller gain under any load model. Simulation results show that the tuning gain of a SVC controller using the ANN approach can provide better damping of the power system over a wide range of load models than the fixed-gain controller.     

基于射影控制的直流输电和静态无功补偿器协调控制

为消除高压直流输电和静止无功补偿器在动态过程中附加阻尼控制的相互干扰,文章设计了基于射影控制的协调阻尼控制器。该控制器以广域信号为反馈输入,根据时滞系统稳定性定理形成参考状态反馈控制系统,基于射影控制原理获得低阶输出反馈控制。时域仿真和特征值分析结果均证明该控制器具有的良好阻尼效果,在不同的时滞下仍然可以很好地提供阻尼。     

提高暂态稳定的励磁与FACTS协调策略设计

灵活交流输电系统(FACTS)元件及发电机励磁系统对远距离输电系统的暂态稳定性有很大的影响。该文针对单机远距离与电网互联系统，提出采用非线性最优变目标策略协调设计发电机励磁、可控串补（TCSC）和静止无功补偿器(SVC)，从而提高首摆稳定性及快速阻尼后续振荡。所提协调方案是基于TCSC在故障期间闭锁时，SVC作为TCSC的辅助控制手段，当故障清除后，立即投入TCSC，从而使TCSC、SVC与发电机励磁同时贡献于暂态稳定性。在整个过程中，采用非线性最优变目标控制策略来协调所有控制器，即在暂态稳定第一摆及后续动态过程中预先设定两个目标：其一是励磁与FACTS输出最大，从而保证系统最大的暂态稳定域；其二是当发电机滑差接近于零时，控制器以阻尼功率振荡为目标，以使系统迅速恢复至稳态。最后采用NETOMAC仿真软件在我国阳城—淮阴输电工程中进行了仿真，并与常规PID控制进行了比较。结果表明，所提策略是正确的，有效的。