基于PSASP的UPFC潮流控制建模与仿真

为了将统一潮流控制器UPFC(unified power flow controlle)r嵌入到商业软件中,采用节点注入电流法建立了UPFC的潮流控制模型。该模型通过控制UPFC串联侧节点的注入电流和并联侧节点的无功注入电流来控制线路潮流和UPFC接入点母线电压,其中,串联侧节点的注入电流通过功率目标方程直接求取,并联侧节点的无功注入电流通过引入被控母线电压的参考值与实际值的偏差求得。基于电力系统分析综合程序PSASP(power system analysis software package)进行了算例研究,结果表明所建模型能有效实现UPFC的潮流控制作用,且具有较快的潮流追踪速度和较高的收敛精度。对其他FACTS(flexible AC transmission system)器件的控制建模具有一定的参考价值。     

基于PSASP用户自定义的UPFC潮流控制模型

为建立与电力系统分析综合程序（PSASP）相适应的统一潮流控制器（UPFC）潮流控制模型,提出一种解耦控制方法。串联侧分别采用串联注入电压的q轴和d轴分量控制线路传输的有功功率和无功功率,并联侧基于瞬时功率理论,采用并联侧电流的q轴分量控制UPFC并联接入点母线电压,通过改变UPFC与网络接口节点的注入电流实现UPFC的潮流控制目标。在国内某500kV电网上进行了潮流控制计算,计算结果表明,所建立的模型正确、可行,完全可用于含UPFC的实际电网的工程研究和分析。     

用于三相电力系统潮流计算的UPFC稳态模型

基于对称分量坐标、用附加节点注入功率法,建立了统一潮流控制器(UPFC)在给定控制方式下计算三相潮流的三序解耦模型;三序解耦潮流采用正序约束条件,UPFC正序模型按附加节点注入功率计算,负序、零序模型按附加节点注入电流计算;结合牛顿—拉夫逊法编制了该潮流计算程序。因潮流可按正序、负序、零序分别求解,在保证求解精度的前提下提高了求解效率。     

含UPFC元件三相电力系统潮流模型和算法的研究

基于附加节点注入功率法,建立了统一潮流控制器( UPFC)在给定控制方式下的三相附加节点注入功率模型.在研究了UPFC 三相附加节点注入功率模型的基础上,运用三相解耦-补偿理论,对三相系统进行潮流计算.通过网络分析,说明了UPFC元件在改善系统的三相不平衡的作用.经算例仿真,验证了建立的UPFC三相潮流模型及运用算法的...     

考虑新型拓扑结构的统一潮流控制器五端功率注入模型

南京西环网中统一潮流控制器(UPFC)装置的串联侧变压器接入220kV铁北—晓庄双回线路,并联侧连接在临近的35kV燕子矶母线,这种新型拓扑结构对UPFC的系统级建模提出了更高的要求,既要考虑UPFC控制双回线路的特点,还要体现UPFC对并联侧母线及后续线路的影响。为此,文中提出了一种适用于新型拓扑结构的UPFC五端功率注入模型,在考虑串联侧控制双回线路且并联侧节点可灵活的情况下,基于注入功率法推导了该模型的数学表达式,并给出了PSASP软件下UPFC五端模型的潮流计算原理和实现方法。在该模型的基础上,进一步实现了UPFC串联侧双线控制策略,并基于南京UPFC工程实际数据进行正常运行状态和串联线路N-1故障的仿真计算,结果验证了该模型的准确性、灵活性和全面性。     

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。     

一种新的UPFC潮流计算模型

以往的统一潮流控制器UPFC(Unified Powernow Controller)的潮流计算模型要用到牛顿一拉夫逊法进行迭代求解，需要重新编制与之相应的潮流计算程序，因此费时费力。现提出一种新的UPFC等值模型，该模型适合利用已有的商业软件计算潮流，无需因为UPFC加入系统而重新编制潮流程序，因而可以大大减少工作量。该模型的主要设计思想是将系统中的UPFC用注入功率和恒定电压等值表示，从而将UPFC从等值网络中移去。该模型分为两部分，第一部分适用于UPFC的控制方式1和方式2，第二部分适用于控制方式3和方式4。一个IEEE—9节点的算例验证了该模型的有效性。     

采用直接电流控制策略的MMC-UPFC小信号模型

基于模块化多电平换流器(MMC)的统一潮流控制器(UPFC)大多采用直接电流控制策略,为分析采用该控制时UPFC接入后系统的小干扰稳定特性,针对一般的3节点拓扑UPFC,推导了其外环控制器、内环控制器、MMC和直流系统的小信号模型,并给出了UPFC输出电流的线性化方程。进一步地推导了传统2节点拓扑UPFC的小信号模型,同时给出了UPFC模型与系统其余部分的组合方法,建立了系统整体的线性化模型。最后,通过对一个2机测试系统进行时域仿真和模态分析,验证了所提小信号模型的正确性。     

UPFC控制器的设计

采用功率模型描述含UPFC的网络方程,在该网络方程基础上并联侧采用电压控制/无功电流控制,串联侧采用自动潮流控制/电压注入的控制策略。提出了UPFC控制器物理实验装置的实现方案。仿真结果证明采用该方法,UPFC能快速有效地改善系统的电压和潮流。     

基于PSASP的UPFC自定义模型在西南电网的应用仿真

采用功率注入法和电流注入法,在PSASP下实现UPFC自定义潮流模型与暂稳模型搭建。给出了川渝断面UPFC安装容量与改变潮流分布的关系,计算了川渝断面动态特性。计算结果表明,UPFC对于改善川渝断面潮流分布有一定作用,但是安装在功率输送通道上的UPFC,单位容量改变所安装通道的潮流不到0.5单位,杠杆作用小。通过串并联侧控制,UPFC对改善功率、电压振荡效果较明显。     

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。     

特高压直流接入背景下的UPFC系统级控制策略

为缓解特高压直流馈入受端电网后造成的多个交流输电通道紧张的问题,提高换流站交流母线暂态电压支撑强度和稳态调压能力,首先基于电网络理论推导了统一潮流控制器(UPFC)对输电线路电流、交流母线电压的控制灵敏度,分析了利用UPFC系统级控制功能(线路有功/无功潮流控制以及并联换流器无功功率控制)实现输电线路过载控制和交流母线电压调节的可行性。在此基础上,提出了一套特高压直流接入背景下的UPFC系统级控制策略,以监控系统运行参数并自动生成满足系统安全稳定约束的UPFC系统级控制指令值。最后,以锦苏直流落点附近的苏南500 kV UPFC示范工程作为仿真算例,验证了所提出的控制灵敏度分析的有效性和UPFC系统级控制策略的可行性。     

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.     

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).     

一种新型的统一潮流控制器设计方法

在介绍统一潮流控制器(UPFC)的构成、电压空间矢量脉宽调制技术及带有UPFC单机无穷大系统的 数学模型之后,采用两种控制策略来设计UPFC。第一部分采用电流预测的d q轴解耦控制策略结合电压空 间矢量脉宽调制技术来调节线路有功功率及无功功率。第二部分采用多输入单输出的自组织模糊神经网络和d q轴解耦控制策略并结合电压空间矢量脉宽调制技术来维持节点电压及电容器端电压的稳定。Matlab仿真结果表明:基于以上两种控制策略的UPFC能有效调节线路的有功功率及无功功率,保证节点电压及电 容器端电压的稳定,证明该     

Optimal location and signal selection of UPFC device for damping oscillation

Unified power flow controller (UPFC) is used for controlling the real and reactive power in transmission line and bus voltage simultaneously and independently. An additional task of UPFC is to increase transmission capacity as result of power oscillation damping. The effectiveness of this controller depends on its optimal location and proper signal selection in the power system network. A residue factor has been proposed to find the optimal location of the UPFC controllers and eigenvalue analyses are used to assess the most appropriate input signals (stabilizing signal) for supplementary damping control of UPFC to damp out the inter-area mode of oscillations. The proposed residue factor is based on the relative participation of the parameters of UPFC controller to the critical mode. A simple approach of computing the residue factor has been proposed, which combines the linearized differential algebraic equation model of the power system and the UPFC output equations. While for signal selection a right-half plane zeros (RHP zeros) and Hankel singular value (HSV) is used as tools to select the most receptive signal to a mode of the inter-area oscillation. The placements of UPFC controllers have been obtained for the base case and for the dynamic critical contingences. The effectiveness of the proposed method of placement and selection of signals are demonstrated on practical network of TNB 25 bus system of south Malaysian network and New England 39 bus system.     

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.