基于部分左特征结构配置的电力系统优化阻尼控制

基于线性系统部分特征结构配置思想,提出了一种电力系统阻尼控制器优化设计方法。利用部分左特征结构配置方法,同时配置闭环主导振荡模态的特征值和特征向量,将多余的设计自由度分配到部分特征向量上,改善电力系统的动态阻尼特性。引入动态补偿器型电力系统稳定器(PSS)替代传统PSS,满足部分左特征结构配置方法对输出反馈变量的要求,提高闭环系统的阶次,使系统特征结构在更高的维度中优化配置。最后,建立加权多目标函数,将阻尼控制器的参数优化设计归纳为一个无约束的单目标非线性规划问题,并通过群搜索(GSO)优化算法求解控制器参数。多种运行条件下的新英格兰10机39节点系统仿真分析表明,采用该方法设计的阻尼控制器能有效抑制电力系统低频振荡,较留数法设计的传统PSS有更好的阻尼控制效果和鲁棒性。     

基于扰动估计观测器的非线性分散控制

为提高多机电力系统的稳定性,提出了一种新型的非线性分散控制器（NDC）。该控制器的设计是基于输入输出反馈线性化控制策略,并采用估计的状态和定义为一个虚拟状态的扰动来反映系统的非线性、不确定和各子系统的外部动态的综合作用。鲁棒滑动模态观测器被用来估计系统的状态和扰动。该控制器的设计不需要系统详细的知识,易于实现分散控制。3机系统的仿真结果表明了所提非线性分散控制器能有效地提高系统的稳定性。     

多机电力系统附加励磁控制器的优化配置

针对多机电力系统附加励磁控制器安装位置选择问题,基于奇异值分解的相关理论,利用传递函数矩阵给出附加励磁控制器安装地点的评价指标.该评价指标不需要系统状态矩阵的QR分解和传递函数留数的计算,通过求解系统输入-输出的传递函数矩阵的最大奇异值及其奇异向量来识别每台发电机对振荡模态的贡献程度,从而简化了计算过程和运算量.将该方法应用于多机电力系统,找出了影响每个振荡模态的最小数目的机组及附加阻尼控制器的最佳配置点,验证了该方法的正确性.     

采用SVD方法的附加阻尼控制器配置

为正确选择附加阻尼控制器的配置点,在建立多机电力系统传递函数矩阵的基础上采用奇异值分解的方法,给出了附加阻尼控制器配置点的评价指标。该评价指标与留数法评价指标具有一致性,通过求解传递函数矩阵的最大奇异值及其奇异向量来识别每台发电机对振荡模态的贡献程度,从而找出附加阻尼控制器的最佳配置点,简化了计算过程和运算量。为了获得复杂电力系统的传递函数,引入普罗尼分析的方法进行传递函数辨识,以给大规模电力系统在线模型辨识提供有利支持。最后将该方法应用于多机电力系统的PSS和SVC附加阻尼控制器配置点选择,分析获得其最佳配置点,验证了配置点的合理性。     

多机系统励磁与SSSC的非线性鲁棒协调控制

针对多机电力系统中,发电机励磁和静止同步串联补偿器(static synchronous series compensator,SSSC)的协调控制问题,引入广义Hamilton系统理论,进行非线性协调控制器设计。SSSC采用考虑内部动态的三阶模型,并将SSSC与各台发电机的相互作用用附加电磁功率表示。将包含发电机励磁和SSSC的多机电力系统描述成广义耗散Hamilton系统形式,利用边界函数法和L2干扰抑制控制方法设计了发电机励磁和SSSC的协调控制器。四机两区域系统的仿真结果表明:与传统的分散控制器相比,所提的非线性协调控制器能够有效地提高系统的暂态稳定性和电压调节性能。     

基于Hamilton理论的多机系统励磁与UPFC的非线性鲁棒协调控制器设计

针对多机电力系统中参数的不确定扰动对系统稳定控制器影响的问题,利用广义耗散Hamilton理论设计了一种新型多机励磁和统一潮流控制器(UPFC)的非线性协调控制器。首先,建立了包含UPFC动态调节作用的多机电力系统动态方程,构造了系统的Hamilton能量函数,从而将系统表示成广义耗散Hamilton系统形式。其次,利用含参数摄动的L_2干扰抑制控制理论设计了多机励磁和UPFC的非线性协调控制器。此控制器设计过程同样适用于含有参数摄动的其他FACTS装置与多机励磁的协调控制器设计。最后,以四机两区域系统进行了仿真分析,结果表明当系统中存在多种参数摄动时,所设计协调控制器能够保证系统的功角稳定、实现UPFC接入点电压的无差调节并且具有较好的鲁棒性。     

大电力系统的解耦及关联测量控制法

本文根据多机电力系统所形成的大系统的特点,导出了关联项与本子系统状态变量及一些可测量的关系,从而得到了大电力系统动态解耦的一个方法。又在大系统关联预估法的基础上导出了分散反馈控制律,它是本子系统的定常增益反馈。在理论上本文提出了一个大电力系统控制解耦方法,在实践上解决了大电力系统分散控制器的设计方法。 本文对三机电力系统进行了数字仿真,用本文提出的关联测量分散控制器所得的系统动态品质完全达到了典型全系统最佳控制的效果。     

基于分散控制理论的多机系统低频振荡抑制

常规的电力系统低频振荡抑制措施是在发电机励磁系统中加装电力系统稳定器(PSS),然而它在多机电力系统中的应用并没有充分的理论研究.将大系统分散控制原理应用于多机电力系统低频振荡抑制问题,只要分散阻尼控制器(DDC)的阶数足够高,分散闭环控制系统的低频振荡模态总可以在复平面内任意配置.分析了PSS与DDC的关系,论证了PSS是DDC的一种特殊形式,因而从理论上说明了DDC比PSS优越.将DDC的优化配置表示为一个带不等式约束的非光滑优化问题并用遗传算法求解.以新英格兰测试系统和我国西北电网为算例的计算结果表明,在发电机励磁系统中加装DDC是一种有效的低频振荡抑制新措施.     

采用低阶动态补偿器的电力系统分散控制

提出一种用低阶动态补偿器抑制电力系统低频振荡的分散控制方法。安装在不同地点的多个低阶动态补偿器通过给定结构输出反馈统一设计,使系统的所有机电振荡模态具有整体最优的阻尼效果。用本地可测量和广域测量系统(wide area measurement system,WAMS)提供的部分关键远方信息共同作为补偿器的输入,从而可使本地振荡模态和区间振荡模态都得到良好的抑制。同时考虑多种运行方式优化控制器参数,使控制器具有更好的适应性;采用区域极点配置保证控制器具有一定的鲁棒性。最后,将控制器的参数求解归结为一个非光滑优化问题,并用梯度采样法进行求解。2个示例系统的仿真结果表明,该文所设计的控制器对低频振荡有着明显的抑制作用,优于传统的电力系统稳定器(power system stabilizer,PSS)。     

基于多工况综合留数及H2／H∞的多回直流系统阻尼控制鲁棒设计方法

直流附加阻尼控制是提高电力系统区域间低频振荡阻尼的有效措施,但阻尼控制器的安装地点和调制信号的选取是影响阻尼控制器性能的重要因素。综合考虑了控制器安装地点和调制信号组合方案对主导模式的可观可控性、对其他模式的耦合作用和对多种运行工况的鲁棒性3个因素,提出了多工况综合留数指标来确定最优方案,所设计控制器的H2/H∞综合性能验证了多工况综合留数指标的有效性。最后,对一个大规模交直流混联系统在多种运行工况、多种故障情况下进行了仿真,仿真结果验证了基于多工况综合留数和H2/H∞的多回直流系统阻尼控制鲁棒设计方法能有效提高系统区间振荡模式的阻尼。     

可控制动电阻控制器广域协调优化方法研究

提出一种基于广域测量系统和三级共态预估算法的可控制动电阻控制器广域协调优化方法.将多机系统中的可控制动电阻控制器分成本地控制器和协调控制器两层,采用三级共态预估算法对分散的本地控制器进行非线性协调优化,使系统获得全局最优的控制效果.所提方法计算量小,并能在本地形成闭环反馈控制,适合于在线应用.仿真结果表明所提方法可以明显提高系统的暂态稳定性,并改善系统的动态品质.     

Simultaneously tuning decentralized nonlinear optimal excitation controllers in multimachine power systems

This paper proposes an approach to simultaneously designing multiple decentralized nonlinear optimal excitation controllers to achieve rotor angle stability improvement and good trade-off between voltage regulation and oscillation damping in multimachine power systems. The approach includes: (1) building a novel state-space mathematical model based on nonlinear feedback compensation, (2) properly formulating the control problem and (3) developing a more quick and accurate algorithm to solve the problem. Case studies are fulfilled in a two-area four-machine power system to verify the effectiveness of the approach. Digital simulation results show that the controllers designed with the proposed method gain much priority over traditional AVR/PSS in damping power oscillation, improving voltage regulation and enhancing transfer capability.     

A decentralized nonlinear feedback controller with prescribed degree of stability for damping power system oscillations

Nonlinear feedback linearization techniques are being used for transforming nonlinear power system dynamics into closed loop systems, whose dynamics are linear over wide range of operating conditions. This facilitates use of linear techniques for designing feedback controllers to damp out oscillations. The advantage of using such feedback controllers is that they do not depend on the system operating conditions unlike the conventional controllers, for example a conventional power system stabilizer. A nonlinear feedback law is proposed in this work, which converts a nonlinear power system into closed loop decentralized linear time varying systems. A feedback controller has been designed using linear quadratic regulator with prescribed degree of stability to stabilize the decentralized linear time varying systems. The performance of the proposed method has been tested on a 16-machine, 68-bus system representing interconnected New England Test system (NETS) and New York Power System (NYPS).     

Nonlinear decentralized disturbance attenuation excitation controlvia new recursive design for multi-machine power systems

In this paper, a new nonlinear decentralized disturbance attenuation excitation control for multi-machine power systems is proposed based on recursive design without linearization treatment. The proposed controller improves system robustness to dynamic uncertainties and also attenuates bounded exogenous disturbances on the system in the sense of L₂-gain. Computer test results on a 6-machine system show clearly that the proposed excitation control strategy can enhance transient stability of power systems more effectively than other excitation controllers     

考虑控制量限幅的发电机非线性分散鲁棒汽门控制

提出了一种冗余控制量情况下考虑控制量限幅的非线性反馈控制方法,这种方法通过在动态过程的任一时间点上求解一个具有不等式约束的最优化问题得到该时刻各控制量值,使实际能够给出的虚拟控制量尽量达到保证系统渐近稳定所需要的虚拟控制量要求。将该方法与引入量测变量的建模方法相结合,设计了可同时考虑高压、中低压缸汽门控制的多机系统非线性分散鲁棒汽门控制器。对一个多机交直流系统的数字仿真表明,所设计的控制器是有效的。     

Stability analysis and decentralizedcontrol of inverter-based ac microgrid

This work considers the problem of decentralized control of inverter-based ac micro-grid in different operation modes. The main objectives are to (i) design decentralized frequency and voltage controllers, to gather with power sharing, without information exchange between microsources (ii) design passive dynamic controllers which ensure stability of the entire microgrid system (iii) capture nonlinear, interconnected and large-scale dynamic of the micro-grid system withmeshed topology as a port-Hamiltonian formulation (iv) expand the property of shifted-energy function in the context of decentralized control of ac micro-grid (v) analysis of system stability in large signal point of view. More precisely, to deal with nonlinear, interconnected and large-scale structure of micro-grid systems, the port-Hamiltonian formulation is used to capture the dynamic of micro-grid components including microsource, distribution line and load dynamics as well as interconnection controllers. Furthermore, to deal with large signal stability problem of the microgrid system in the grid-connected and islanded conditions, the shifted-Hamiltonian energy function is served as a storage function to ensure incremental passivity and stability of the microgrid system. Moreover, it is shown that the aggregating of the microgrid dynamic and the decentralized controller dynamics satisfies the incremental passivity. Finally, the effectiveness of the proposed controllers is evaluated through simulation studies. The different scenarios including grid-connected and islanded modes as well as transition between both modes are simulated. The simulation conforms that the decentralized control dynamics are suited to achieve the desired objective of frequency synchronization, voltage control and power sharing in the grid-connected and islanded modes. The simulation results demonstrate the effectiveness of the proposed control strategy.     

不确定互联电力系统的分散鲁棒控制

针对不确定互联电力系统,提出了一种分散鲁棒输出反馈控制器的设计方法.为了使参数不确定性符合工程实际和简化控制器的求解,引入数值界的形式对不确定性进行描述.该方法将控制器的设计归结为一组矩阵不等式的求解问题,采用同伦迭代算法,通过固定不同的变量,将非线性矩阵不等式转化为两组线性矩阵不等式并交替求解.仿真结果表明所获得的控制器使得互联电力系统鲁棒稳定,阻尼转矩充足,满足给定的性能指标,并且具有良好的抑制大扰动的能力.     

Decentralized suboptimal control of a complex power system using the modified Bellman-Lyapunov equation

This paper is concerned with the decentralized control of the dynamic behaviour of a complex power system. Two different approaches are suggested here for the design of suboptimal decentralized controllers using the modified Bellman-Lyapunov equation via optimal techniques. In the first approach, suboptimal control laws for the turbine power are constructed with the aid of a special Lyapunov function for the system as a whole. This method of attack aims at ensuring suboptimal dynamic conditions for the system as a nonlinear large-scale dynamic system. In the second approach, suboptimal control laws are deduced with the aid of a vector Lyapunov function, which is constructed by the decomposition of the power system into interconnected subsystems.     

Decentralized coordinated control for large power system based on transient stability assessment

For the purpose of enhancing transient stability of large power systems, this paper focuses on an issue of decentralized coordinated control. A modified equal area criterion (MEAC) is firstly proposed as the transient stability judgment criterion of multi-machine power systems. Then, a hierarchical decentralized coordinated excitation control is designed, which consists of both upper level coordinated control and lower level decentralized control. Based on the transient stability assessment, the coordinated controller determines whether to send coordinated control signal to lower level decentralized controllers. Moreover, the decentralized coordinated controller is designed by using H_∞ robust control method so as to deal with the uncertainties of system. Finally, simulation studies test effectiveness of the proposed control.     

Enhancement of interconnected power system stability using a control strategy involving static phase shifters

The static phase shifting transformer is one of the potential options of the recently proposed FACTS (flexible AC transmission systems). Promising results have been obtained for enhancing the small-disturbance and the transient stability of interconnected power systems.

In this paper, the important concept of involving in the same control strategy both generating units and static phase shifters has been considered. A systematic procedure for designing co-ordinated and decentralized controllers of these components is provided to assure a satisfactory dynamic performance of an interconnected power system under both small and large perturbations. The approach uses optimal control theory as a basis for the co-ordination of static phase shifter and governor controllers. A suboptimal decentralized control scheme is derived from the designed optimal controller by using a ‘minimum norm’ nearness criterion. The resulting feedback control signals for each generating unit and for each phase shifter is expressed in terms of measurable and local variables only.

Test results show the effectiveness of the proposed control strategy and the usefulness of control actions on static phase shifters.