STATCOM与SSSC改善电力系统阻尼的比较研究

电力系统故障过程中暂态能量的消失速率可以作为系统能否快速到达静态平衡点的一个标准,同时也可以看作系统阻尼的一个指标.基于这个理论,针对静止无功补偿器(STATCOM)和静止同步串联补偿器(SSSC)在系统故障过程中对系统作用的不同,分析并得出了一个单机无穷大系统故障过程中STATCOM与SSSC向系统提供的附加阻尼的表达式.仿真结果表明,STATCOM与SSSC都能够显著改善系统阻尼,但SSSC比STATCOM能更好地为系统提供阻尼,改善系统动态性能.     

Novel reactive power controllers for the STATCOM and SSSC

The paper investigates the dynamic operation of both static synchronous compensator (STATCOM) and static synchronous series compensator (SSSC) based on a new model comprising full 48-pulse GTO voltage source converter for combined reactive power compensation and voltage stabilization of the electric grid network. These key FACTS devices are power electronic GTO converters connected in parallel or series with the power system grid and are controlled by novel decoupled controllers. The complete digital simulation of the STATCOM and SSSC within the power system is performed in the MATLAB/Simulink environment using the power system blockset (PSB). The STATCOM scheme and the electric grid network are modeled by specific electric blocks from the power system blockset while the control system is modeled using Simulink. Two novel controllers for the STATCOM and SSSC are presented in this paper based on a decoupled current control strategy to ensure stable operation of the STATCOM under various load excursions. A novel control scheme for the static synchronous series compensator (SSSC) is also implemented to provide a full controllable series compensating (buck/boost) injected voltage over a specified capacitive and inductive range, independently of the magnitude of the transmission line current. The series reactive compensation scheme with an external dc power supply can also compensate for any voltage drops across resistive component of the transmission line impedance. The novel decoupled controller uses a phase locked loop (PLL) with a novel reduced inherent time delay to improve the transient performance of the SSSC. The performance of both STATCOM and SSSC schemes connected to the 230 kV grid are evaluated. The proposed novel control schemes for the STATCOM and SSSC are fully validated by digital simulation.     

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.     

Effects of STATCOM,TCSC, SSSC and UPFC on static voltage stability

The purpose of this paper is to study the effects of four FACTS controllers: STATCOM, TCSC, SSSC and UPFC on static voltage stability in power systems. Continuation power flow is used to evaluate the effects of these devices on system loadability. Applying saddle node bifurcation theory with the use of PSAT, effects of these devices controllers on maximum loading point are determined. Static voltage stability margin enhancement using STATCOM, TCSC, SSSC and UPFC is compared in the modified IEEE 14-bus test system.     

利用SSSC装置抑制电力系统低频振荡的研究

研究了电力系统低频振荡及其产生机理,并理论分析了静止同步串联补偿器(SSSC)对抑制电力系统低频振荡的作用。建立包含SSSC的单机无穷大系统的数学模型,推导该模型的非线性动态方程。利用在稳定运行点线性化的方法,以SSSC输出电压的相角和幅值调制系数为控制变量,设计了SSSC的暂态控制器,并将其用于提高系统阻尼,抑制电力系统低频振荡。在Matlab/Simulink中搭建包含SSSC的单机无穷大系统及暂态控制器的模型进行仿真验证,结果表明理论分析的正确性以及所提出的暂态控制策略的有效性。     

采用STATCOM抑制次同步谐振的理论与仿真研究

针对静止同步补偿器（STATCOM）在抑制次同步谐振（SSR）方面的理论与应用进行了研究。分析了STATCOM抑制SSR的基本工作原理;提出了STATCOM抑制SSR的控制策略,并设计了相应的控制器,以IEEE第一标准模型为例,采用特征值分析和时域仿真分析2种方法验证STATCOM对SSR的抑制效果。此外,利用PSCAD/EMTDC电磁暂态仿真软件,建立了锦界电厂串补送出系统的电磁暂态仿真平台,并进行了相应的仿真分析。仿真结果表明,STATCOM能有效抑制SSR的发生,为解决国内外交流串补输电工程中的SSR问题提供了参考,也为STATCOM装置的应用提供了依据。     

Optimal power flow with FACTS devices by hybrid TS/SA approach

In this paper, a hybrid tabu search and simulated annealing (TS/SA) approach is proposed to minimize the generator fuel cost in optimal power flow (OPF) control with flexible AC transmission systems (FACTS) devices. The problem is decomposed into the optimal setting of FACTS parameters subproblem that is searched by the hybrid TS/SA approach and the OPF with fixed FACTS parameters subproblem that is solved by the quadratic programming (QP). Two types of FACTS devices are used: thyristor-controlled series capacitor (TCSC) and thyristor-controlled phase shifting (TCPS). Test results on the modified IEEE 30 bus system indicates that the proposed hybrid TS/SA approach can obtain better solutions and require less CPU times than genetic algorithm (GA), SA, or TS alone.     

A proposal for investment recovery of FACTS devices in deregulated electricity markets

The paper presents a methodology to quantify the benefits, in terms of monetary values, of FACTS devices when used in deregulated electricity market for congestion management. The proposed methodology is used in the proposal for investment recovery of FACTS devices. Despite the long history of development and mature technology, the practical installations of FACTS devices are still limited. The main reasons for few installations are high investment cost and lack of viable measures to quantify the long list of benefits offered by FACTS device. In this respect, the methodology proposed in the paper provides a promising solution. The proposed methodology is based on establishing pricing schemes with and without FACTS devices using OPF formulation. The volume of market with FACTS devices and the increase in surplus due to them forms the basis of quantifying their benefits. The pricing scheme does not destroy the incentive effect in short run and also makes possible the provision of merchant FACTS. The proposed concept was tested and validated with TCSC in five-bus test system. Result shows that, when TCSC is used to relieve congestion in the system and the investment on TCSC can be recovered.     

基于多FACTS的网侧协调阻尼控制机理研究

柔性交流输电装置(flexible AC transmission system,FACTS)在提升电网安全稳定和运行效率方面发挥着重要的作用。随着柔性交流输电装置在电力系统中的广泛应用,研究系统中多FACTS的协调控制机理对于实现系统的协调阻尼控制具有重要的理论价值和现实意义。针对实现多FACTS协调控制过程中遇到的交互影响问题,提出基于选择模式分析(selective modal analysis,SMA)和多变量频域控制理论的多FACTS交互作用机理分析方法,通过SMA实现多FACTS交互作用的有效特征量提取,进而通过多变量频域控制理论推导出多FACTS间的交互作用关系和发生条件,并在此基础上揭示多FACTS间交互作用机理。研究结果表明:处于多机系统同一电力区域中的多台FACTS阻尼控制器间存在相互制约的关系,当控制器参数满足负交互条件时会发生比较明显的负交互作用,严重时甚至威胁系统的安全运行,当控制器参数满足协调运行条件时才能保证多FACTS间的协调运行与控制。通过仿真验证了文中机理研究的正确性以及在实际电网中应用的可行性。     

Power flow control and solutions with multiple and multi-type FACTS devices

In this paper, a new generalized current injection model of the modified power system using Newton–Raphson power flow algorithm has been proposed for desired power transfer with Flexible AC Transmission Systems (FACTS) devices. So that the FACTS devices can be incorporated in the proposed algorithm and, therefore, whole system with these devices can be easily converted to power injection models without change of original admittance and the Jacobian matrices. Power flow algorithm has been modeled in such a way that it can easily be extended to multiple and multi-type FACTS devices by adding a new Jacobian corresponding to that new device only. Power flow algorithm with the presence of Thyristor Controlled Series Compensators (TCSC), Unified Power Flow Controller (UPFC), and Generalized Unified Power Flow Controller (GUPFC) has been formulated and solved. To demonstrate the performance of the proposed algorithm for multiple and multi-type FACTS devices, different case studies of IEEE 30-bus system has been considered and the results are tabulated. The proposed algorithm is independent of the size of the system and initial starting conditions of the FACTS devices.     

A new modeling and placement of shunt FACTS devices in the secondary voltage regulation environment

Recently, the Secondary Voltage Regulation (SVR) is installed in some power systems in order to ensure the coordination voltage control devices. In other hand, the shunt FACTS devices such as the Static Var Compensator (SVC) and the STATic COMpensator (STATCOM) are extensively used for the local voltage control without any coordination with other voltage control devices, without any reciprocal coordination. In this paper, new models of SVC and STATCOM are proposed to be adopted in power flow models that include the SVR. The proposed models are implemented and tested on a model of the Italian power system. Furthermore, a new method based on sensitivity analysis is proposed to find the most sensitive placements for the installation of SVC and STATCOM. The results obtained show the highly computational performance of the propose models and also the effectiveness of the sensitivity analysis to find the best placements of SVC and STATCOM taking into account the SVR.     

Improvement of first swing stability limit by utilizing full benefit of shunt FACTS devices

This paper proposes a new control strategy of shunt flexible ac transmission system (FACTS) devices to improve the first swing stability limit of a simple power system. It is shown that the speed based bang-bang control (BBC) is unable to use the entire decelerating area in maintaining stability. The proposed control strategy improves the stability limit first by maximizing the decelerating area and then fully utilizing it in counterbalancing the accelerating area. This requires to continue the operation of shunt FACTS devices at full capacitive rating until the machine speed reaches a reasonable negative value during the first return journey. Afterwards, the control can be switched to continuous type to improve system damping in subsequent swings. The proposed control strategy is then applied to both static var compensator and static synchronous compensators placed in a single machine infinite bus system. The same control strategy is also used for some faults in a multimachine system. In both the systems, it is found that the proposed control can provide significantly higher stability limit than that of the BBC. The mechanism of improving the stability limit is also described.     

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。     

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.     

具有FACTS设备的多目标电网规划

提出了具有灵活交流输电(FACTS)设备的多目标妥协规划模型,综合考虑了FACTS设备对电网规划的经济性和可靠性两方面的影响,并采用混合遗传-模拟退火算法求解了该模型.算例结果表明FACTS设备能够提高电网规划的经济性及经济性与可靠性的综合水平,并证明了多目标电网规划妥协模型及其解算方法的有效性.     

采用STATCOM与SEDC的多机系统次同步谐振抑制措施

并列同型的多台汽轮机组通过带串补线路送出时可能发生次同步谐振(subsynchronous resonance,SSR)。出力不均衡时,各机组轴系扭振行为不一致,在幅值和相位上均有差别。以双机系统为例,对并列多机系统发生SSR时各机组轴系扭振行为的差异进行了研究。时域仿真结果表明,将各机组发电机转速均取作输入信号时,仅采用静止同步补偿器(static var compensator,STATCOM)便可抑制所有机组的轴系扭振,但是抑制速度缓慢;以网侧STATCOM为主、机侧附加励磁阻尼控制(supplementary excitation damping,SEDC)为辅的联合SSR抑制措施可以结合SEDC和STATCOM各自作为SSR抑制措施的优点,快速有效地抑制多机系统SSR。     

A non-dominated Sorting Hybrid Cuckoo Search Algorithm for multi-objective optimization in the presence of FACTS devices

In this paper, a proposed Non-dominated Sorting Hybrid Cuckoo Search Algorithm (NSHCSA) for multi objective optimal power flow problem with FACTS devices namely Thyristor Controlled Series Compensator (TCSC) and Static Synchronous Series Compensator (SSSC) with different objective functions including the installation cost of FACTS devices are presented. The practical and operating constraints are considered for this analysis. The location of the FACTS device is selected to enhance the system security with respect to minimizing line overloads and bus voltage violations. The proposed Hybrid Cuckoo Search Algorithm (HCSA) is the combination of Cuckoo Search Algorithm (CSA) and Genetic Algorithm (GA). For multi objectives selected Pareto front is obtained by using the fuzzy decision making tool. The effectiveness of the proposed method is tested on standard IEEE-30 bus test system in the presence of the TCSC and SSSC. The results are analyzed and compared with existing methods.     

STATCOM与SVC的性能比较与应用分析

分析了静止同步发生器(static synchronous compensator,STATCOM)与静止无功补偿装置(static var compensation,SVC)的工作特性与基本原理;对STATCOM与SVC的性能从多角度进行了比较。得出STATCOM具有响应速度快、控制方法先进、谐波含量少等优点,并对实际应用做了分析和介绍。指出了STATCOM是无功补偿与谐波抑制综合技术的发展方向,也是电能质量研究的重点内容。     

基于多FACTS的网侧阻尼协调控制量化指标研究

研究多变量系统等效开环过程(effective open-loop process,EOP)理论在电力系统多柔性交流输电装置(flexible AC transmission system,FACTS)协调控制量化分析中的应用,并提出基于EOP的多FCATS阻尼控制器交互作用分析方法及量化指标。推导电力系统阻尼控制框架下的 EOP,在此基础上建立用于多FACTS阻尼控制器分析的阻尼控制等效开环过程(damping control effective open-loop process,DCEOP)。提出基于 DCEOP 谱半径和多变量 Nyquist 推广定理的多FACTS阻尼控制器交互影响分析方法,可以判断系统中是否存在多FACTS阻尼控制器的负交互作用。进一步推导并提出基于DCEOP的多FACTS交互风险因子和交互作用因子,实现了多FACTS阻尼控制器协调控制及交互作用的量化分析。最后,通过算例分析验证了所提方法的正确性以及在实际电网中应用的可行性。     

电力电子和FACTS装置数字仿真软件包的研究与开发

介绍新研发的电力系统电力电子及FACTS装置仿真软件包EMTPE，其中包括电力电子装置的数值计算方法、大量全控型电力电子器件的模型、相量实时测量控制模块、过电压闪络率计算方法、工作平台与人机界面、总体合成及FACTS装置仿真等。给出一些算例以演示新计算方法的效果。