基于观测解耦状态空间的多机励磁非线性分散最优控制策略

为进一步改善多机系统的暂态稳定性,结合直接反馈线性化原理和最优控制理论推导出多机系统中励磁的分散控制规律。该控制策略是根据多机电力系统观测解耦状态空间得出,只需要当地信号实施控制,驱动子系统到达局部平衡点,就能使全系统达到稳定。仿真结果表明,该控制规律能够较好地提高多机电力系统的暂态稳定性。     

MICROPROCESSOR BASED NONLINEAR EXCITATION CONTROLLER FOR SYNCHRONOUS MACHINES

ABSTRACT

The synchronous machines in power systems have the excitation systems of field winding to improve the transient stability of power systems. The synchronous machines are nonlinear systems, however, the excitation systems have been designed based on linearized systems, because the stability analysis of nonlinear systems is difficult and the generalized control method of nonlinear systems has not been developed yet.

This paper proposes a nonlinear excitation controller for synchronous machines in power systems. For the sake of simplification of the nonlinear state feedback control, this paper considers both the transient stability and the suppression of the rotor swings in transient conditions. The effect of the automatic voltage regulator (AVR) for the synchronous generator is not discussed here. This controller is designed based on Lyapunov's direct method that can directly judge the stability of nonlinear systems. The usefulness and validity of the proposed excitation controller are confirmed by numerical simulations and experiments. The microprocessor based generator excitation system that consists of a nonlinear controller, state variable detector, and PWM inverter, is constructed. The nonlinear excitation controller can improve the transient stability of synchronous machines.     

发电机励磁及SVC非线性最优协调控制

发电机励磁和静止无功补偿器(static var compensator,SVC)对远距离输电的稳定性有很大影响。为了提高系统在大扰动情况下的暂态稳定性,提出一种发电机励磁系统与SVC协调非线性最优控制方法。通过建立发电机励磁与SVC系统的综合模型,将微分几何反馈线性化理论与线性最优控制理论相结合,设计了发电机励磁与SVC系统的非线性最优协调控制规律。控制信号实现了本地化,避免了远距离的信号传输。仿真结果证明,该控制方法能同时改善系统的功角稳定性和电压稳定性。     

基于零动态和变结构控制的发电机汽门和励磁非线性综合控制

针对电力系统暂态过程的非线性特性,利用励磁控制和汽门控制的特点,以功角和电压稳定为目标提出一种发电机汽门和励磁综合控制思想。励磁控制以稳定电压为目标,结合基于零动态和变结构控制的概念和原理进行设计,有效地维持了电压水平。汽门控制以功角稳定为目标,通过计算零动态系统的暂态能量函数,利用Lyapunov稳定理论,得到稳定流形作为切换面,然后设计相应的变结构非线性汽门控制律,将零动态系统限制在所设计的稳定流形上。变结构控制的特性使控制律具有一定的鲁棒性。汽门控制设计中未使用任何线性化方法,因而控制律对系统的非线性特性完全适应。试验结果表明所设计的控制器不仅对小干扰和大干扰暂态过程具有很好的稳定作用,而且在动态过程中能很好地稳定电压,动态过程具有更好的供电品质。     

提高交直流系统暂态稳定性的最优变目标控制策略

提出一种用于改善交直流互联系统暂态稳定性的非线性控制策略。通过建立多机电力系统观测解耦状态空间模型，应用最优变目标控制策略推导出HVDC与发电机励磁的综合控制规律。该控制策略只需要当地实施控制，首先驱动系统达到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。仿真结果表明，该控制规律能较好地提高交直流互联系统的暂态稳定性。     

Boost变换器带恒功率负载状态反馈精确线性化与最优跟踪控制技术研究

分析了Boost变换器带恒功率负载的特性，推导出系统传递函数并得到系统稳定运行条件。采用状态反馈精确线性化技术对系统进行控制。根据Boost变换器带恒功率负载的特点，将最优跟踪技术应用于精确线性化控制中，得到系统非线性控制律。用SABER软件对得到的控制律进行了仿真。仿真结果表明：精确反馈线性化结合最优跟踪可以对Boost变换器带恒功率负载系统进行有效的控制，使系统具有理想的稳态特性和动态响应，在电源及负载大范围变化时，保证系统的稳定运行，满足不同类型负载的要求，具有大信号稳定特性。     

多机系统快速汽门非线性控制研究

首先介绍了最优控制系统综合的李雅普诺夫方法和一种简单实用的非线性系统大 范围线性化方法，然后将之成功地应用于同步发电机快速汽门控制器的设计，避免了构造 非线性系统李雅普诺夫函数的困难，为电力系统暂态稳定控制的研究作出了新的探索。获得 的控制器完全基于当地量的反馈，易于工程上在线实现。     

同步发电机暂态过程励磁非线性控制

首先介绍了基于能量函数的最优控制系统综合李雅鲁诺夫方法和一种简单实用的非线性系统大范围线性化方法。然后根据电力系统的具体特点，将其成功地应用于同步发电机暂态过程励磁控制器的设计，为电力系统暂态稳定控制的研究作出了新的尝试。     

多机电力系统变结构励磁控制器的设计研究

基于多机电力系统的非线性模型,利用状态反馈精确线性化方法和变结构控制理论,提出了一种新的电力系统变结构励磁控制器设计方法。在设计中取消了参考机,并实现了多机系统的分散控制。3机系统的仿真结果表明,提出的变结构励磁控制器可以有效地改善系统在大干扰下的暂态稳定性。     

A nonlinear geometric approach to power system excitation control and stabilization

In this paper, a unified approach to the design of a nonlinear excitation controller/power system stabilizer for a synchronous generator/infinite bus power system is presented. The approach is based on a form of state feedback linearization, known as input–output feedback linearization, which provides an exact semi-global state transformation that is valid for a large class of operating points of the power system. With this transformation, the terminal voltage becomes a linear function of the control input. The excitation controller/power system stabilizer is then synthesized by using linear controller design techniques. The controller is proven to provide small signal stability and to provide local asymptotic tracking of admissible constant reference signals for a large class of operating points. A procedure is given to tune the controller gains to provide significant damping of the power angle oscillations.     

双轴励磁同步发电机的微分反馈非线性最优励磁控制

本文在微分几何理论的基础上，提出了更简明、更适合工程用的面向多输入系统的微分反馈补偿物理精确线性化方法，解决了电力系统控制设计中的强非线性问题及鲁棒性问题，并据此推导了双轴励磁同步发电机的微分反馈非线性最优励磁控制规律。仿真结果表明，所设计的控制方式能较大幅度地提高系统的动态稳定性和暂态稳定性。     

基于暂态能量函数的电力系统非线性鲁棒滑模励磁控制

针对电力系统暂态过程的非线性特性,以功角稳定为目标设计了一种状态反馈非线性滑动模励磁控制器.通过直接计算系统的暂态能量函数,利用Lyapunov稳定理论,得到稳定流形作为切换平面,然后设计相应的滑动模励磁控制律,将系统限制在所设计的稳定流形上.在设计时考虑了对系统参数不稳定性,从而控制律具有一定的鲁棒性.设计中未使用任何线性化方法,因而控制律对系统的非线性特性完全适应.仿真结果表明所设计的控制器不仅具有良好的小干扰稳定性,而且对于大干扰暂态过程也具有很好的抑制作用.     

考虑机端电压限制的多重非线性变结构励磁控制

针对电力系统暂态过程的非线性特性,设计了一种考虑电压限制的多重非线性变结构励磁控制器,根据控制目标将控制器分2层设计。下层控制器由稳定控制和电压限制控制组成。稳定控制通过计算系统的暂态能量函数,得到稳定流形作为切换面,然后设计相应的变结构非线性励磁控制律,将系统限制在所设计的稳定流形上,以稳定系统;电压限制控制则利用零动态原理,使电压回复到限制区内。上层控制器通过适当的切换律,将下层控制器进行切换,在稳定系统和限制机端电压之间进行协调。在设计时考虑了系统参数不确定性,从而控制律具有一定的鲁棒性。稳定控制设计中未使用任何线性化方法,因而控制律对系统的非线性特性完全适应。实验结果表明所设计的控制器在稳定系统的同时,有效的限制了机端电压。     

Robust adaptive output feedback control of nonlinearly parameterized systems

The ideas of adaptive nonlinear damping and changing supply functions were used to counteract the effects of parameter and nonlinear uncertainties, unmodeled dynamics and unknown bounded disturbances. The high-gain observer was used to estimate the state of the system. A robust adaptive output feedback control scheme was proposed for nonlinearly parameterized systems represented by input-output models. The scheme does not need to estimate the unknown parameters nor add a dynamical signal to dominate the effects of unmodeled dynamics. It is proven that the proposed control scheme guarantees that all the variables in the closed-loop system are bounded and the mean-square tracking error can be made arbitrarily small by choosing some design parameters appropriately. Simulation results have illustrated the effectiveness of the proposed robust adaptive control scheme. Translated from Journal of Sichuan University (Engineering Science Edition), 2006, 38(4): 136–140 [译自: 四川大学学报 (工程科学版)]     

观测线性化追踪目标励磁控制

利用同步相量测量单元(PMU)测量电压相位角，通过相位角的在线追踪观测，实现状 态 方程式的线性化，在这种理论的基础上提出了追踪目标励磁控制(TOEC)。仿真结果 表明：在提高系统稳定极限和改善系统动态特性方面TOEC均优于线性最优励磁控制(LOEC) ，TOEC不仅可以实现电力系统闭环线性化控制，还具有使系统的状态逼近某一目标的能力 。     

Recurrent neural networks-based multivariable system PID predictive control

A nonlinear proportion integration differentiation (PID) controller is proposed on the basis of recurrent neural networks, due to the difficulty of tuning the parameters of conventional PID controller. In the control process of nonlinear multivariable system, a decoupling controller was constructed, which took advantage of multi-nonlinear PID controllers in parallel. With the idea of predictive control, two multivariable predictive control strategies were established. One strategy involved the use of the general minimum variance control function on the basis of recursive multi-step predictive method. The other involved the adoption of multistep predictive cost energy to train the weights of the decoupling controller. Simulation studies have shown the efficiency of these strategies. Translated from Acta Scientiarum Naturalium Universitatis Nankaiensis, 2006, 39(1): 49–53 [译自: 南开大学学报 (自然科学版)]     

基于双层规划的非线性鲁棒电力系统稳定器参数整定方法

使用先进的励磁控制技术是改善电力系统稳定性和动态品质的有效手段。采用反馈线性化和鲁棒控制理论设计的非线性鲁棒电力系统稳定器(NR-PSS)是一种先进的励磁控制装置。在深入研究电力系统稳定器(PSS)参数整定原理和NR-PSS现有参数整定方法的基础上,提出了一种基于双层规划的NR-PSS线性部分参数整定方法,以满足阻尼频带宽和控制代价低两方面要求。通过等价非线性规划可求出最优参数。仿真结果表明,应用所提出方法设定的参数可以改善NRPSS的控制效果。     

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     

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。     

An augmented automatic choosing control of observer type for nonlinear systems with linear measurement and its application to power systems

This paper deals with a feedback control using automatic choosing functions and the observer-control design procedure for nonlinear systems with linear measurement. A constant term which arises from linearization of a nonlinear equation is treated as a coefficient of a stable zero dynamics. A given nonlinear system is linearized piecewise so as to be able to design the linear optimal controllers with the linear observers. By the automatic choosing functions, these controllers are smoothly united into a single nonlinear feedback controller, which is called an augmented automatic choosing control of observer type. This controller is applied to a transient stability of power systems, whose simulation results show that the new controller enables to expand the stable region well. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.