串联FACTS装置提高区域间可用传输能力的数值研究

对利用串联FACTS装置提高区域间可用传输能力问题进行了数值计算研究。给出了含有FACTS装置的求解区域间可用输电能力的优化模型和求解方法,并用算例进行了分析验证。研究结果表明,采用最优潮流的方法对ATC问题进行求解,可以较方便地考虑FACTS的控制,得到其最优的控制参数;在输电网络的潮流有可调节容量余度的条件下,FACTS可以有效地提高可用输电能力,使网络的输送容量得以充分利用。     

计及FACTS装置的可用输电能力计算

利用功率注入法,建立广义统一潮流控制器(generalized unified power flow controller,GUPFC)和线间潮流控制器(interline power flow controller,IPFC)的数学模型。将GUPFC和IPFC的目标控制约束及运行约束即内部功率平衡约束和考虑等效功率注入模型的潮流约束嵌入到最优潮流计算模型中,得到计及GUPFC和IPFC的可用输电能力(available transfer capability,ATC)计算模型,并利用跟踪中心轨迹内点法对模型进行求解。IEEE-30节点系统的仿真计算显示GUPFC对节点电压和多条线路甚至某一子网络潮流的灵活控制能力及IPFC对线间潮流的合理分配能力;同时验证模型和算法的有效性和可行性。     

基于SSSC装置的系统可用输电能力研究

可用输电能力(ATC)是衡量互联电网安全性与稳定性的重要指标,而灵活交流输电技术(FACTS)是提高系统可用输电能力的有效途径。以提高可用输电能力为目的,将静止同步串联补偿器(SSSC)引入互联电力系统。首先利用功率注入法,建立SSSC的稳态数学模型,然后基于最优潮流法,将SSSC的功率注入模型加入潮流方程,建立了计及SSSC的可用输电能力计算模型,并采用原对偶内点法对其进行求解。为了确定装置的安装位置,利用特征结构分析法,根据最小模特征值对控制变量的灵敏度系数来选择最有利于提高输电能力的SSSC安装位置。利用IEEE-30节点系统进行仿真计算,结果显示安装SSSC后互联系统间的传输容量得到提高,稳定裕度也得到提升,合理地配置SSSC可以有效提高系统的可用输电能力。     

考虑静止同步串联补偿器的可用输电能力研究

基于静止同步串联补偿器(static synchronous series compensator, SSSC)建立了可用输电能力计算的最优潮流模型,并在模型中引入了SSSC的功率注入模型进行优化,采用原-对偶内点法对优化后的模型进行求解,根据特征结构分析法确定SSSC的最佳安装位置.利用IEEE 30节点系统进行仿真...     

考虑SSSC装置的可用输电能力研究

可用输电能力是衡量互联网络安全性与稳定性的重要指标,而灵活交流输电系统是提高系统可用输电能力的有效途径.基于一种串联补偿型的FACTS装置-静止同步串联补偿器,建立了ATC计算的最优潮流模型,在模型中引入了SSSC的功率注入模型,采用原对偶内点法对其进行求解,并且根据特征结构分析法确定了SSSC装置的最佳安装位置.利用...     

风电并网系统区域间概率可用输电能力计算

为了准确评估风电场接入电网对系统可用输电能力(Available Transfer Capability,ATC)的影响,针对风电并网系统的概率可用输电能力计算展开研究,详细分析不同风电并网情况下ATC的变化规律。首先基于风速Weibull分布,建立了大型风电场输出功率数学模型;进而采用原-对偶内点法完成风电并网系统可用输电能力单一样板值的求解。在此基础上,采用蒙特卡罗仿真法从广义角度对风电并网系统的ATC进行概率评估。仿真结果表明,所提算法能够有效评估风电这种波动性电源对ATC的影响。研究成果可为风电并网系统安全经济性能评估提供有效参考信息,对未来电网规划扩建具有指导意义。     

基于最优潮流并计及静态电压稳定性约束的区域间可用输电能力计算

可用输电能力(ATC)是衡量电力系统在安全稳定运行的前提下区域间功率交换能力的指标。文中基于最优潮流(OPF)方法，建立起符合电力市场交易机制的ATC计算模型，其中考虑到输电线路故障对系统静态电压稳定性的影响，加入线路N-1故障时广义参数化形式的潮流方程及相应的不等式约束条件，使系统在故障时仍有负荷裕度，以保持电压稳定；以支路功率和系统负荷裕度之间的灵敏度指标进行预想故障选择，并用原对偶内点法计算得到输电线路N-1安全约束下的区域间可用输电能力。IEEE30和IEEE118节点系统算例表明该模型和算法的正确性与有效性。     

输电系统可用传输能力的研究

针对电力工业市场化改革的需求，综述了在电力市场环境下，输电网可用输电能力ATC（Available Transfer Capability)计算问题的研究现状及发展方向，介绍了ATC的定义，分析限影响ATC准确计算的各种不确定因素，针对ATC在线计算和离线计算的特点，提出了ATC计算的确定性模型和概率性模型，分析比较了目前ATC计算的几种算法的优,缺点，最后，展望了输电网可用输电能力计算中有价值的研究方向。     

基于电压稳定约束下的交直流系统可用传输能力计算

将基于电压稳定约束下的交直流混合系统的可利用传输能力求解问题归结为非线性规划问题,并运用原始-对偶内点法来求解优化模型.首先由交直流网络间的耦合关系和换流器转换方程,推导出直角坐标系交直流系统的Jacobi、Hessian矩阵,然后针对交直流系统控制方式的改变提出分段求解的方法求解电压稳定约束条件下的可用传输能力.仿真算例验证了该龄算法能方便考虑直流变量约束及运行方式的调整,且对初始值选择要求不高,收敛迭代次数少.     

基于最优潮流的广域FACTS控制提高输电能力

讨论了利用最优潮流进行基于广义测量的二次控制问题。研究表明FACTS控制器如不装备广义测量控制则不能充分发挥其控制潜能。提出了可协调和优化控制器设定点,从而增加静态最大负荷能力的新控制策略。此外,对基于远方测量反馈控制的简单方案和基于在线最优的通用方案进行了研究。最后,以一实例定量评估了基于广义测量的FACTS控制的效果。     

Comprehensive comparison of FACTS devices for exclusive loadability enhancement

A complete comparison of a number of well‐known flexible alternating current transmission system (FACTS) devices for static voltage stability enhancement is presented. Various performance measures including power–voltage (P–V) curves, voltage profiles, and power losses are compared under normal and contingency conditions. The importance of proper modeling of FACTS devices, including the DC side, is emphasized because, at their limits, most of these devices behave like a fixed capacitor or inductor. A simple placement technique of series FACTS devices and unified power flow controller (UPFC) is proposed considering exclusive loading margin enhancement. A new idea of loading margin increase per cost is proposed to find the appropriate FACTS devices for investment. The paper provides a guide for utilities to have an appropriate choice of FACTS device for enhancing static voltage stability and loading margin by comparing technical merits and demerits of each of these devices in terms of system performance. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Loadability enhancement with FACTS devices using gravitational search algorithm

In the present work, GSA (gravitational search algorithm) based optimization algorithm is applied for the optimal allocation of FACTS devices in transmission system. IEEE 30 & IEEE 57 test bus systems are taken as standards. Both active and reactive loading of the power system is considered and the effect of FACTS devices on the power transfer capacity of the individual generator is investigated. The proposed approach of planning of reactive power sources with the FACTS devices is compared with other globally accepted techniques like GA (Genetic Algorithm), Differential Evolution (DE), and PSO (Particle Swarm Optimization). From the results obtained, it is observed that incorporating FACTS devices, loadability of the power system increases considerably and each generator present in the system is being able to dispatch significant amount of active power under different increasing loading conditions where the steam flow rate is maintained corresponding to the base active loading condition. The active power loss & operating cost also reduces by significant margin with FACTS devices at each loading condition and GSA based planning approach of reactive power sources with FACTS devices found to be the best among all the methods discussed in terms of reducing active power loss and total operating cost of the system under all active and reactive loading situations.     

基于电压稳定及FACTS配置的输电能力的研究

输电能力是电网技术的重要指标,也是反映电网输电容量的市场信号。介绍了考虑电压稳定性后,采用线路电压稳定指标快速筛选出严重预想事故集,并用连续潮流法计算输电能力;同时叙述了采用临界状态下线路电压稳定指标来评估FACTS配置安装地点对输电能力的影响,以快速捕获最佳安装位置。通过IEEE5节点和IEEE30节点标准系统验证了此方法的有效性。     

计及FACTS装置的概率特征根分析

概率特征根分析计及了较宽范围的系统运行方式变化,利用柔性交流输电系统FACTS(Flexible AC Transmission System)装置上的附加控制器可以改善系统的动态特性,将现有的概率特征根分析扩展到包含FACTS功能模块。以并联型静态无功补偿器SVC(Static Var Compensator)和串联型可控串联补偿器TCSC(Thyristor-Controlled Series Capacitor)为例,在原有概率特征根模型的基础上,依据具体的元件模型和控制器表达,确定了形成系统状态空间方程时的相应线性化表达式;详细讨论了功能增加后系统状态方程矩阵的形成;通过补充相关的灵敏度计算,完成了计及FACTS装置的电力系统多运行方式下的小干扰稳定性分析。最后,在一个八机系统上进行了试算。在选定的附加控制器参数下,比较了增加SVC前后的系统主导特征根的变化,考察了附加控制器增益变化对临界特征根的影响。     

Steady-state optimization in power systems with series FACTS devices

This paper presents an optimization-based methodology to identify key locations in the AC network where placement of a series-connected FACTS device increases the maximum megawatt power transfer the most. The models used for the thyristor-controlled series capacitor (TCSC) and unified power-flow controller (UPFC) include the nonlinear constraints of voltage limitation, zero megawatt active-power exchange, voltage control, and reactive-power exchange. This article describes briefly the steady-state flexible AC transmission systems (FACTS) models and their integration in an existing optimal power-flow (OPF) software package designed and implemented by the authors. A reduced real-life network is used for the case studies. The optimization results help in evaluating the effectiveness of the series FACTS devices in maximizing the network transfer capability and deliver a measure of the FACTS ratings.     

Locating series FACTS devices for congestion management in deregulated electricity markets

This paper proposes two new methodologies for the placement of series FACTS devices in deregulated electricity market to reduce congestion. Similar to sensitivity factor based method, the proposed methods form a priority list that reduces the solution space. The proposed methodologies are based on the use of LMP differences and congestion rent, respectively. The methods are computationally efficient, since LMPs are the by-product of a security constrained OPF and congestion rent is a function of LMP difference and power flows. The proposed methodologies are tested and validated for locating TCSC in IEEE 14-, IEEE 30- and IEEE 57-bus test systems. Results obtained with the proposed methods are compared with that of the sensitivity method and with exhaustive OPF solutions. The overall objective of FACTS device placement can be either to minimize the total congestion rent or to maximize the social welfare. Results show that the proposed methods are capable of finding the best location for TCSC installation, that suite both objectives.     

A new formulation for load flow solution of power systems with series FACTS devices

This paper addresses the solution of load flow equations for a power system with series flexible AC transmission systems (FACTS) devices. A novel formulation of equations using dual state variables (current magnitude and angle) and dual control variables (series injected real power and series voltage in quadrature with current) for series devices is proposed. These specifications can be related to transmission line loading and device limits. Specifications like power flow through a series device can also be handled using this formulation. The load flow equations are solved using Newton-Raphson technique. A decoupled formulation is also proposed. Case studies are carried out on IEEE test systems with several types of specifications to validate the method.     

Analysis of radial distribution systems with embedded series FACTS devices using a fast line flow-based algorithm

Analysis of radial distribution systems with embedded series Flexible AC Transmission System (FACTS) devices is facilitated by a formulation of power flow equations with bus voltage magnitudes and line flows as independent variables. Since control variables such as the line and bus reactive powers figure directly in the formulation, handling the control action of FACTS devices in distribution systems is direct and easily implemented. Using the Breadth-First-Search (BFS), the bus incidence matrix of a radial distribution system is first rendered strictly upper diagonal, leading to reduced computational effort. All the common FACTS device models under steady-state conditions are easily incorporated in the new framework by a simple process of "variable swapping." Using IEEE standard systems, the line flow-based (LFB) formulation is shown to provide easy implementation with multiple series and shunt FACTS devices in the system and enable direct evaluation of the FACTS device ratings.