用于电力系统仿真的潮流控制器模型

本文描述了—族基于可关断晶闸管（ＧＴＯ）电压源逆变器的电力系统控制装置，介绍了静补（ＳＴＡＴＣＯＮ）、串联潮流控制器（ＳＰＦＣ）和统一潮流控制器（ＵＰＣ）的稳态模型。静补是由美国的ＥＰＲＩ、ＴＶＡ和西屋科技中心联合开发的基于逆变器的并联装置、不久它将被安装在ＴＶＡ的１６ｌｋＶ输电系统上用于控制线路电压。而串联潮流控制器和统一潮流控制器则代表了静补在串联应用方面的拓展。这些装置的建模可以结合到现有的大型电力系统分析程序之中供系统稳态研究使用。ＩＥＥＥ的３０母线试验系统的仿真结果证明了这些电压源潮流控制装置的稳态性能。ＵＰＦＣ具有能同时对线路的有功与无功潮流独立地进行控制的能力，可以认为它特别适用厂输电潮流控制。     

一种新型统一潮流控制器

传统统一潮流控制器（UPFC）价格昂贵,损耗高,谐波含量高,在电力系统中不能很好地推广使用。文中提出一种混合型UPFC,它由“Sen” Transformer（ST）和传统UPFC串联组成,ST通过控制普通的有载调压开关,实现360°离散可调串联电压,UPFC利用电力电子开关原理实现360°连续可调的串联电压,两者共同工作起到控制系统潮流的作用。与传统大容量UPFC相比,混合型UPFC使用小容量UPFC,能够达到大容量UPFC的潮流控制范围,具有成本低、效率高、电磁兼容性好、谐波含量低、易于实现的优点,解决了导致现阶段UPFC不能推广使用最为重要的成本问题。混合型UPFC是具有极高性价比和效率的潮流控制器件,具有广阔的应用前景。     

UPFC模糊控制器设计及在市场环境下应用

研究了统一潮流控制器UPFC(UnifiedPowerFlowController)在缓解输电阻塞和优化系统潮流方面的应用。利用UPFC的串联电压调整、线路参数串联补偿、移相控制等功能,一方面可以提高电气元件的利用效率,进而提高系统的输电能力,缓解和解决输电阻塞现象;另一方面,还可以用来强制地调节线路的潮流走向,以改变系统整体的潮流分布,优化系统潮流。通过详细分析UPFC的等效电路模型,建立了新的参考坐标系,实现了对UPFC串联与并联侧的解耦控制。并且为了进一步增强系统的鲁棒性,采用了带有自调整因子的模糊策略对UPFC进行控制,此模糊控制器可以根据系统的实际情况实时地改变控制策略,以便更好地适应电力系统强非线性等特点。仿真结果证明,UPFC可以有效地提高系统输电能力以缓解输电阻塞,并且可以根据需要,迅速平滑地调节系统潮流走向,以优化系统潮流,节约输电成本。     

统一潮流控制器的建模与控制研究综述

灵活交流输电系统（ＦＡＣＴＳ）技术是近几年来出现的一项新技术,统一潮流控制器（ＵＰＦＣ）是ＦＡＣＴＳ控制器中乞今最全面的控制器,可提供对传输线路参数（即电压、线路阻抗和相角）的全面动态控制,能够快速控制传输线路的有功和无功功率及母线电压。首先由考虑ＵＰＦＣ的电力系统潮流调节问题讨论了ＵＰＦＣ的建模,然后从控制角度综述了目前国内外研究ＵＰＦＣ的最新成果,概述了ＵＰＦＣ的各种控制策略,并分析了ＵＰＦＣ     

统一潮流控制器的分析与控制策略

文中分析了统一潮流控制器（UPFC）系统的电压、无功功率和有功功率的平衡,得到了与UPFC控制相关的2个重要结论。首先,分析表明在UPFC输入端电压保持不变的情况下,线路无功潮流的变化实际上是由并联变换器提供的;其次,UPFC端电压既可以从发送端控制也可以从接收端控制。基于以上分析,提出了一种新颖的UPFC控制策略。在该策略中并联变换器控制UPFC直流母线电压和输电线无功潮流,而串联变换器控制UPFC输入端母线电压幅值和输电线有功潮流。同时,在控制系统中加入有功／无功功率协调控制,可在潮流调节中获得良好的静态、动态性能。最后,通过实验验证了所提出的控制策略的有效性。     

UPFC的交叉耦合控制及潮流调节能力分析

研究了UPFC控制传输线路潮流能力，通过对系统功率平衡及UPFC的潮流控制特性分析，在三维空间中绘出了UPFC各部分的功率运行曲面，为有效选取UPFC各部分的功率容量和判断潮流控制方案的可行性提供了一个直观的手段，说明了在UPFC中采用交叉耦合控制的可行性。利用串联变换器注入传输线路电压的d轴分量控制传输线路上的无功潮流，用q轴分量控制传输线路上的有功潮流。控制系统设计中利用频率特性法得到了功率环PI调节器的参数。实验结果表明采用文中所述的控制策略能够使UPFC有良好的潮流调节性能。     

Investigation of SSR characteristics of unified power flow controller

The unified power flow controller (UPFC) is the most versatile flexible ac transmission system (FACTS) controller which can be used to control active and reactive power flows in a transmission line in addition to the bus voltage. The active series compensation is provided by injecting series reactive voltage. The voltage at the two ports of UPFC are regulated by control of shunt current and series real voltage. It also has several operating control modes such as voltage and power regulation, line impedance compensation, etc. This paper presents the analysis and study of sub-synchronous resonance (SSR) characteristics of UPFC. The various combination of operating modes of shunt and series converters are considered for investigating their effect on SSR characteristics.The analysis of SSR with UPFC is carried out based on frequency domain method, eigenvalue analysis and transient simulation. The frequency domain method considers D-Q model of UPFC for the computation of damping torque for quick check in determining torsional mode stability. The study is performed on IEEE First Benchmark Model (FBM).     

适合城市电网的级联型统一潮流控制器

为提高上海地区10 kV电网的供电可靠性,需要潮流控制能力强的柔性交流输电(flexible AC transmissionsystems,FACTS)装置来实现10 kV电网的合环运行,而统一潮流控制器(unified power flow controller,UPFC)就是一种很好的选择。文章对基于H桥级联技术的UPFC拓扑结构进行了研究,通过仿真实验对级联型UPFC的动态性能进行分析和验证。仿真实验结果表明,省略掉串联变压器的H桥级联型,UPFC能够有效控制线路潮流并维持直流电压恒定,采用脉宽调制技术有效消除了中低次谐波。     

Strategies for handling UPFC constraints in steady-state power flowand voltage control

The unified power flow controller (UPFC), with its unique combination of fast shunt and series compensation, is a powerful device which can control three power system parameters. In planning and designing such devices in power systems, power engineers must consider the impact of device internal limits on its performance. This paper develops a power injection model (PIM) based UPFC control approach to consider a number of internal limits imposed on the UPFC, including series injection voltage magnitude, line current through the series inverter, real power transfer between the shunt inverter and series inverter, shunt side current and shunt injection voltage magnitude. Constrained control strategies are proposed and tested on a 28-node test system. The numerical results illustrate the effectiveness of the proposed method     

Real and reactive power coordination for a unified power flow controller

This paper proposes a new real and reactive power coordination controller for a unified power flow controller (UPFC). The basic control for the UPFC is such that the series converter of the UPFC controls the transmission line real/reactive power flow and the shunt converter of the UPFC controls the UPFC bus voltage/shunt reactive power and the DC link capacitor voltage. In steady state, the real power demand of the series converter is supplied by the shunt converter of the UPFC. To avoid instability/loss of DC link capacitor voltage during transient conditions, a new real power coordination controller has been designed. The need for reactive power coordination controller for UPFC arises from the fact that excessive bus voltage (the bus to which the shunt converter is connected) excursions occur during reactive power transfers. A new reactive power coordination controller has been designed to limit excessive voltage excursions during reactive power transfers. PSCAD-EMTDC simulation results have been presented to show the improvement in the performance of the UPFC control with the proposed real power and reactive power coordination controller.     

电力潮流灵活控制技术应用综述

统一潮流控制器(unified power flow controller, UPFC)、静止同步串联补偿器(static synchronous series compensator, SSSC)、可控串联补偿装置(thyristor controlled series compensation, TCSC)和移相器(phase-shifting trans former, PST)能够调节线路参数、灵活控制潮流变化,均已在国内外电网中实现工程应用,对均衡输电通道潮流、提升供电能力有重要作用。文中对UPFC、SSSC、TCSC和PST的理论研究和工程实践进行了综述。首先,分析了4种潮流控制装置的基本结构和控制原理,并介绍了国内外已投运工程的运行情况;其次,从结构、换流器技术、选址定容、控制策略、故障保护5个方面对潮流控制装置的关键技术研究现状进行概述;最后,展望了潮流控制装置在未来电网中的典型应用场景,并对潮流控制技术的研究方向进行了分析。     

基于连续潮流法分析UPFC对电力系统潮流的控制

统一潮流控制器（UPFC）作为一种典型的FACTS装置,综合了FACTS元件的多种灵活控制手段。采用基于功率注入法的统一潮流控制器（UPFC）稳态模型,结合连续潮流法分析了UPFC在电力系统中的潮流控制特性。最后算例表明,UPFC可以控制线路的潮流分布,有效地提高电力系统的稳定性。     

美国INEZ变电站统一潮流控制器简介

统一潮流控制器（UPFC）是灵活交流输电系统（FACTS）中功能最强、最有应用前景的一种控制系统。文中介绍了由美国AEP、EPRI和西屋电气公司共同研制的UPFC装置的原理、性能特点及其应用，并与常规控制装置进行了比较。该装置的功能包括电压调整、串联补偿、相角调整及多功能潮流控制等。它能增加电力传输容量，提供电压支撑，从耐提高了输电系统的可靠性。     

Power system damping enhancement using unified power flow controller (UPFC)

The Unified Power Flow Controller (UPFC) can inject voltage with controllable magnitude and phase angle in series with a transmission line. It can also generate or absorb controllable reactive power. UPFC is expected to be able to damp power system oscillations more effectively than power electronics devices such as SVG and TCSC. In this paper, a control system design of a UPFC for power system damping enhancement based on the eigenvalue control method is proposed. It is made clear that the best design method for the power system damping enhancement is to determine steady‐state values of the UPFC control variables and the control parameters of the UPFC such as gains and time constants simultaneously, because the controllability of UPFC depends on the steady‐state values of UPFC and the power flow condition. The effectiveness of the proposed control system taking into account UPFC inverter ratings is verified by digital time simulation. Furthermore the effects of the input signals to the UPFC controller on small‐signal stability and transient stability enhancement are studied, and it is made clear that UPFC controllers using global information are more effective for power system damping enhancement than those using local information because global information has stronger observability for power system oscillations than local information. © 2000 Scripta Technica, Electr Eng Jpn, 133(3): 35–47, 2000     

Control Lyapunov functions for controllable series devices

Controllable series devices (CSD), i.e., series-connected flexible AC transmission systems (FACTS) devices, such as unified power flow controller (UPFC), controllable series capacitor (CSC) and quadrature boosting transformer (QBT) with a suitable control scheme can improve transient stability and help to damp electromechanical oscillations. For these devices, a general model, which is referred to as an injection model, is used. This model is valid for load flow and angle stability analysis and is helpful for understanding the impact of the CSD on power system stability. Also, based on Lyapunov theory a control strategy for damping of electromechanical power oscillations in a multi-machine power system is derived. Lyapunov theory deals with dynamical systems without inputs. For this reason, it has traditionally been applied only to closed-loop control systems, that is, systems for which the input has been eliminated through the substitution of a predetermined feedback control. However, in this paper, we use Lyapunov function candidates in feedback design itself by making the Lyapunov derivative negative when choosing the control. This control strategy is called control Lyapunov function (CLF) for systems with control inputs     

A real-time control system for single-phase unified power flow controllers

This paper proposes a real-time control system for a single-phase unified power flow controller (UPFC) which is constructed as a pilot power-quality compensation equipment of an electrical railway, and shows simulation and experimental results. For simulation, the control system is modeled in the form of block diagrams by using the Simulink, where the main control effort is focused on the power flow control with the UPFC and the hysteresis current controller is adopted to control the single-phase inverters of the UPFC. And for a small-scale rapid prototyping of the UPFC-equipped control system, the simulation blocks are modified and a real-time control platform is developed by using the real-time workshop and multiple digital signal processors. Both simulation and experiment results have proved the effectiveness of the proposed control system.     

基于统一潮流控制器(UPFC)的电力系统潮流控制

统一潮流控制器(UPFC)作为一种典型的FACTS装置,综合了FACTS元件的多种灵活控制手段.基于UPFC的基本原理、数学模型,介绍具有UPFC的电力系统的潮流计算方法.算例表明,UPFC可以控制线路的潮流分布,有效地提高电力系统的稳定性.     

Unified power flow controller models for three-phase power flow analysis

In this paper, three models of the unified power flow controller (UPFC) suitable for three-phase power flow analysis in polar coordinates are presented. The symmetrical components control model can be used to control the positive-sequence voltage of the shunt bus and the total three-phase active and reactive power flows of the transmission line while the injected shunt voltages and the series voltages are balanced, respectively; the general three-phase control model can be used to control the three shunt phase voltages and the six independent active and reactive power flows of the transmission line; the hybrid control model can be used to control the positive-sequence voltage of the shunt bus and the six independent active and reactive power flows of the transmission line. The proposed UPFC models were successfully implemented in a three-phase Newton power flow algorithm in polar coordinates. In the implementation of these UPFC models, transformers of some common connection types, which connect the UPFC with the network, are explicitly represented. Numerical results based on a five-bus system and the modified IEEE 118-bus system are given to illustrate the UPFC control models and demonstrate the computational performance of the three-phase Newton power flow algorithm.     

Decoupling Controller Design and Controllable Regions Analysis for the Space Vector Modulated Matrix Converter-Unified Power Flow Controller in Transmission Systems

The flexible alternating current transmission systems (FACTS) devices are essential components of the transmission system to enhance the controllability and elevate the transfer capacity of the network. The unified power flow controller is known as the most versatile device in the FACTS family. This work studies a distinctive unified power flow controller (UPFC) structure based on the direct matrix converter to regulate the active and reactive power in a transmission system. In contrast to the conventional UPFC, there is no requirement for a bulky energy storage element in this structure. This results in various benefits including: decreased system volume, improved efficiency, prolonged lifetime, reduced maintenance and removal of the DC-link control. The full power controllable regions are analyzed and graphically obtained for the MC-UPFC, which facilitates the selection of proper UPFC ratings. The working principles and a model of the MC-UPFC are put forward and discussed, followed by explanations of direct space vector modulation (SVM) for this application. Based on the SVM modulation scheme, PID controllers are developed to control power flows in a double-line transmission system. In addition, decoupling controllers are derived by feeding back the coupling components into controllers. The numerical simulation results for a double-line transmission system corroborate the feasibility and effectiveness of the proposition.     

柔性交流输电系统交直流潮流可靠性评估模型

根据串联补偿器(TCSC)、晶闸管控制移相器(TCPST)和统一潮流控制器(UPFC)的工作原理,从交流和直流潮流的视角建立了潮流计算和最优负荷削减模型,采用状态枚举法在RBTS可靠性测试系统中进行分析和验证,结果表明采用交流潮流模型能更准确评估FACTS元件对系统可靠性的影响;而直流潮流模型计算耗时较少,且当节点电压约束不是刚性约束时,所得结果与交流潮流模型结果相近.