Decentralized robust adaptive neural dynamic surface control for multi‐machine excitation systems with static var compensator

Focusing on solving the control problem of the multimachine excitation systems with static var compensator (SVC), this paper proposes a decentralized neural adaptive dynamic surface control (DNADSC) scheme, where the radial basis function neural networks are used to approximate the unknown nonlinear dynamics of the subsystems and compensate the unknown nonlinear interactions. The main advantages of the proposed DNADSC scheme are summarized as follows: (1) the strong nonlinearities and complexities are mitigated when the SVC equipment are introduced to the multimachine excitation systems and the explosion of complexity problem of the backstepping method is overcome by combining the dynamic surface control method with neural networks (NNs) approximators; 2) the tracking error of the power angle can be kept in the prespecified performance curve by introducing the error transformed function; (3) instead of estimating the weighted vector itself, the norm of the weighted vector of the NNs are estimated, leading to the reduction of the computational burden. It is proved that all the signals in the multimachine excitation system with SVC are semiglobally uniformly ultimately bounded.     

基于能量函数的多机系统暂态过程励磁控制研究

采用最优控制系统综合的李雅普诺夫方法研究多机系统暂态过程励磁非线性控制，考虑了控制系统的非线性结构，控制量的有界约束和整个系统的动态品质，获得的控制规律具有较好的解耦和鲁棒特性，仿真结果检验了方法的正确性和有效性。     

一种弱磁扩速下的异步电机磁链观测和速度辨识

针对异步电机在高速弱磁下的运行特点,提出了一种基于弱磁下的高性能的磁链观测方法。该方法在基于转子磁链定向电流模型下,设计了一个可以补偿磁链观测误差的补偿器,解决了弱磁条件下励磁磁场变化而导致磁链观测不准的问题。在改进磁链观测的基础上,运用了易于在定点芯片上实现的转速辨识算法,估算出电机转速。最后将结合改进磁链观测的速度估计器应用到无速度传感器矢量控制系统中,仿真结果表明,这种方法实现方便,能够在弱磁高速下准确的辨识磁链和转速估计,提高控制系统的动态性能。     

多机系统的非线性自适应分散稳定控制

针对含有未知参数的励磁系统,提出了一种非线性自适应控制设计方法,通过递推方法得到了自适应控制策略,而且在控制策略中包含了对未知参数的动态估计,最后获得了多机系统的非线性自适应分散励磁控制策略的一般表达式,在控制策略中所有的变量都是可量测的,而且控制量只与本机组的状态量有关,与其他机组的状态量和输电网络的参数无关,因此控制策略具有分散性和适应性,在一个６机系统上的仿真结果表明了非线性自适应控制器的有     

Simple quasioptimal control of excitation for stabilization of multimachine power system

A closed loop quasioptimal excitation control strategy has been developed for a multimachine power system problem. The control is obtained directly as a function of angle, frequency and acceleration of the different synchronous generators of the system. A modification of the control proportional to the switching function is proposed. Response with both bang-bang quasioptimal and proportional control schemes was compared with that of a basic exciter regulator for the multimachine system. It was observed that both feedback strategies are much superior to the basic scheme, the proportional controller being preferable in terms of realization and smooth voltage regulation.     

多机电力系统再同步最优变目标控制

本文在最优目标控制（ＯＡＣ）的基础上，根据电力系统再同步的特点，提出再同步最优变目标控制（ＯＶＡＣ）策略。该控制策略首先驱动系统到达按最大稳定域选择的人工中间稳定平衡点，然后才驱动系统到达所希望的稳定平衡点。所得到的再同步励磁和快关汽门综合控制规律是根据多机电力系统观测解耦状态空间模型导出的，仅需要获得局部信息，而且能形成闭环反馈控制，因此容易实现。通过数字仿真表明，最优变目标控制能使电力系统快速可靠地再同步。     

Stabilization control for multimachine system using decentralized H∞ excitation controller realizing terminal voltage control and damping control

In this paper, to achieve both damping of power system oscillation and terminal voltage control simultaneously on a multimachine power system, we propose a decentralized H_∞ excitation controller. In the proposed method, H_∞ control via the Normalized Coprime Factorization approach is used to achieve the proposed design idea. By the Normalized Coprime Factorization approach, the weighting function in H_∞ control design is simplified, and output feedback controllers that take into account the realities and constraints of the power systems are designed. The proposed controller is subjected to model reduction of H_∞ controllers, and is transformed to a discrete system to perform digital control by computer systems in consideration of application to a real system. We verify that the proposed excitation controller can achieve both damping of power system oscillation and terminal voltage control by computer simulations of a multimachine power system. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 147(1): 33–41, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10254     

Adaptive control of robots by linear time-varying dynamic position feedback

A simple linear adaptive controller based on a reduced-order observer is proposed to treat the trajectory tracking control problem of robotic systems with unknown parameters and external disturbances. The novelty of our result lies in the fact that the controller is a linear time-varying dynamic position feedback compensator; the dimension of the observer, which is constructed only to estimate the velocity signal, is half the dimension of the robotic system and the attraction region of the closed-loop error system can not be only arbitrarily preassigned but also explicitly constructed. Moreover, as the adaptation is switched off, the boundedness of all the variables is still guaranteed and the trajectories of the closed-loop error system converge to any desired region. If the regressor matrix satisfies the persistent excitation condition, then our control algorithm also guarantees that the estimated values of the unknown parameters converge to the true ones.     

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。     

A Digital Computer Method to Evaluate Load Rejection Overvoltages on a Series Compensated Line with Static Shunt Compensator

A method of analysis for computing dynamic overvoltages following load rejection on a series compensated line with static compensator is presented in this paper. The method incorporates detailed models of a synchronous machine, excitation systems, a series compensated transmission network and a static shunt compensator. The problem has been simulated on an ICL 2960 computer system. The receiving-end voltage envelopes following load rejection were evaluated for a typical 400 kV system having different levels of series compensation with a static compensator. These studies are useful for choosing the kind and quantum of compensation required for a particular power system.     

多机电力系统的频谱拟合

本文采用最小二乘估计方法对多机电力系统的频谱进行拟合。根据不同阶次模型的拟合误差的大小即可确定对某台发电机采用几阶模型最为合适。这对多机电力系统中同步发电机的励磁控制器设计具有一定的指导意义。对一个实际电力系统的计算表明:多机电力系统中一般的同步发电机采用3阶模型是合适的;对于转动惯量相当大的机组可采用2阶模型。     

Dynamic Stabilization of Power Systems through Reactive Power Modulation

ABSTRACT

This paper demonstrates the significant benefits in the dynamic stability improvement of power systems by reactive power modulation in response to a local control signal derived from bus frequency. Static var compensator (SVC) with a thyristor controlled reactor scheme is considered for reactive power modulation.

The benefits of reactive power modulation are dependent on the location of SVC in a multimachine system. A simple criterion based on eigenvalue aensitivity is proposed for the prediction of the effectiveness of the damping control. An illustrative example is given to demonstrate its utility.     

Robust multimachine power systems control via high order sliding modes

This article presents a formal study of the transient stabilization problem, including a stability proof. A decentralized nonlinear robust control scheme for multimachine electrical power systems is presented. The mathematical model takes into account the interconnections between electrical elements of the power system such as generators, electric networks, loads and exciters. Each generator is considered as a seventh order system that includes the mechanical and rotor electrical dynamics with static exciter dynamics. The proposed control scheme is based on the Block Control methodology and Second Order Sliding Modes technique using the Super Twisting algorithm. A nonlinear observer is designed to estimate the rotor fluxes of the synchronous machines. The designed decentralized control scheme requires the only local information for each local controller. This control scheme was tested through simulation on the well known reduced 9 buses equivalent model of the WSCC system.     

Equivalent turbogenerator model for design of multivariable controllers in multimachine systems

The design of multivariable controllers for turbogenerators is usually based on single-machine infinite-bus representations, which are not valid for multimachine power systems. Alternatively, an overall control strategy may be sought for all the generators in the system, but this arrangement is not feasible in practice and involves major mathematical difficulties. The paper describes a method for designing physically-realizable multivariable controllers for individual turbogenerators in multimachine systems, without the assumption of an infinite bus. This employs an equivalent model for each generator, which includes the effects of interconnections with other units in the power system. The method has been used to design optimal state-space controllers for a three-machine system, and results obtained by nonlinear computer simulation show that good performance is achieved.     

基于输入-输出线性化的交流励磁发电机控制

根据单机无穷大系统中交流发电机(ACEG)的状态方程,推导出ACEG的四阶控制模型。基于模型的多变量、非线性,将输入-输出线性化理论应用到交流励磁发电机的控制中,得到输入-输出线性化方程。对线性方程用线性最优控制,得出以发电机功角、有功功率和无功功率为反馈控制量的非线性励磁控制规律。对线性化中重要的零动态问题进行了研究,保证所得控制系统的稳定性。单机无穷大系统仿真结果表明,这种输入-输出线性化的控制对增强系统稳定性具有一定的作用。     

解决超调问题的220kV变电站无功配置方法

针对220 kV变电站单组补偿容量配置偏大、感性与动态无功补偿缺乏引起的电压调控困难问题,提出了220 kV变电站离散与连续相结合的综合无功补偿方案,由一组直接式静止同步补偿器(static synchronous compensator,STATCOM)和采用开关柔性控制技术的并联电容器组组成补偿系统。首先构建了变电站无功补偿调压估算模型和指标——无功超调率,该指标揭示了当前变电站无功补偿配置组数有限和单组容量不宜过大之间的矛盾,使得220 kV变电站采用所提的新型补偿方案成为了解决受端系统的稳态电压控制的精度和暂态电压稳定的超调问题的根本出路。算例表明紧急状态下所提方案能给电网提供有效的动态电压支撑。     

SVC与发电机励磁的非线性变结构协调控制

针对电力系统的强非线性和不确定性特点及精确反馈线性化的不足,引入自抗扰控制技术设计了能同时改善电力系统功角稳定和电压动态特性的静止无功补偿(SVC)与发电机励磁的变结构协调控制器。扩张状态观测器的动态补偿作用不仅使励磁控制与SVC控制实现解耦,而且使二者均能实现当地信号控制。仿真结果表明提出的非线性鲁棒变结构协调控制器能有效地改善系统的动态稳定性。所设计的控制器对系统运行点和网络结构的变化具有良好的适应性和鲁棒性。     

带零动量轮航天器的逆系统方法姿态控制

为满足带零动量轮航天器姿态响应的快速性与准确性,将航天器姿态模型和飞轮机构及其补偿器视为广义控制对象,采用广义逆系统方法与内模原理相结合设计了复合控制器。在分析动量轮的摩擦阻力效应基础上,设计了基于飞轮非线性观测器的低、高速补偿器,在改变航天器惯量与加入干扰的情况下,通过仿真分析了复合控制的鲁棒性。逆系统实现了广义控制对象的解耦,内模闭环控制器弥补了解耦的非理想性,补偿器加快了姿态响应速度。仿真结果表明,逆系统与内模控制组成的复合控制器对带零动量轮航天器姿态控制是有效的,并且该控制器对航天器惯量参数和干扰具有较强的鲁棒性。     

基于观测器的控制时滞线性系统的最优跟踪控制

研究了控制时滞线性系统的二次型最优跟踪控制问题.首先将控制时滞系统转化为无时滞系统,再将最优跟踪问题转化成等价系统的最优调节问题.然后,通过求解Riccati方程,设计含动态观测器的前馈-反馈最优跟踪控制律,利用构造参考输入观测器解决了前馈补偿器的状态物理不可实现问题.仿真实例验证了所设计的最优跟踪控制律的有效性.     

计及动态负荷的电力系统静止无功补偿器(SVC)与发电机励磁控制

基于微分代数控制系统的反馈线性化方法，进一步研究了具有非线性负荷的电力系统中静止无功补偿器(Static var compensator，SVC)和发电机三阶模型的励磁控制，表明具有非线性负荷和SVC装置的NDAS(3)仍可以通过状态反馈精确线性化，从而得到具有代数方程的Bnmovsky标准型。提出了具有非线性负荷的电力系统SVC与发电机励磁控制的完全精确线性化设计。该控制方法可以同时满足发电机功角稳定和SVC节点处电压。仿真结果表明该方法具有很好的效果和优越性。