Adaptive speed control of hydrogenerators by recursive leastsquares identification algorithm

An inherent challenge to hydrogenerator speed regulation is the nonlinear and time varying nature of the process. When a fixed gain controller is used to regulate such a process, globally stable system response can be achieved only at the expense of degraded off design-point performance. This paper considers the application of an adaptive control methodology that allows the controller gains to automatically adjust to changing process variables and thereby provide uniform closed loop response over a wide range of operating conditions. Preliminary findings derived from a calculated plant model, and a standard recursive identification technique, indicate that the adaptive system provides desirable dynamic response despite changes in system operating dynamics, maintaining stable operation in situations where constant gain schedules fail     

考虑尾流效应的风电场减载出力优化控制

在高风电渗透电力系统中,风电场参与系统调频普遍忽略了尾流效应对风电机组出力的影响。文章提出了一种考虑尾流效应的风电场减载出力优化控制方案。首先,采用改进Jensen尾流模型,给出了任意风向的尾流区域划分方法;其次,在满足系统调频需求的前提下,以风电场有功出力最大为目标,对风电场功率分配进行优化;然后,针对不同风速区间设置了相应的优化控制方案,并给出方案的具体实现方法;最后,以江苏某海上风电场为例进行算例仿真,算例结果表明,所提方案可有效地提高风电场整体出力。     

Speed control of a three-phase induction motor based on robust optimal preview control theory

A synthesized method for speed control of a three-phase induction motor (IM) based on optimal preview control system theory is implemented in this article. An IM model comprises three-input variables and three-output variables that coincide with the synchronous reference frame that is implemented using the vector method. The input variables of this model are the stator angular frequency and the two components of the stator space voltage vector, whereas the output variables are the rotor angular speed and the two components of the stator space flux linkage. The objective of the synthesized control system is to achieve motor speed control, field orientation control, and constant flux control. A novel error system is derived and introduced into the control law to increase the robustness of the system. The preview feed-forward controller, which includes the desired and disturbance signals, is used to improve the transient response of the system. A space vector pulse-width modulation (PWM) control technique for voltage source-fed IM is prepared for microprocessor-based control. Spectral analysis of the output voltage is evaluated to predict the effect of the proposed space vector modulation technique on the dynamic performance of the IM. The optimal preview controlled system is implemented, and its applicability and robustness are demonstrated by computer simulation and experimental results.     

基于LQG-I的风力发电机组优化控制策略研究

文章针对风电系统的随机性、不确定性和未建模动态等特征,提出了LQG-I优化控制策略。首先,运用机理分析的方法建立了风力发电系统数学模型。在此基础上,设计了LQG-I控制策略,既保留了LQG在克服随机扰动方面的优势,又利用了积分控制在解决系统的不确定性和未建模动态方面的优势。为了进一步改善对系统的控制性能,采用粒子群优化算法对加权矩阵Q,Qe,R的参数进行整定。最后,以高风速区功率和发电机转矩优化控制问题为例,在matlab/simulink平台下仿真验证了所提优化控制策略的可行性和有效性。仿真结果表明:所提出的LQG-I优化控制策略能够实时跟踪风速的变化,保证发电机角速度、转矩和输出功率的稳定;在同等条件下,该控制策略比传统LQG控制器性能更优越。     

基于最优控制的半主动悬挂机车非线性稳定性分析

半主动悬挂系统是我国目前高速列车悬挂系统发展的最佳形式,而采用天棚阻尼半主动悬挂控制策略恶化了轮对的稳定性性能,降低了临界速度。采用最优控制的方法,对车辆悬挂系统的半主动控制策略进行了优化研究,同时利用动力学仿真软件Simpack建立一个2Co轴式机车控制模型,并对优化后的控制策略进行了非线性稳定性分析。结果表明,采用最优控制的半主动悬挂控制策略,不但不会降低机车的非线性临界速度,而且还会使得其收敛速度明显加快,振动幅值也相应地变小。     

基于一致性协议的配电网分布式优化控制策略研究

分布式控制以其鲁棒性强、可扩展性强等突出优势,已逐渐取代集中式控制,成为高渗透率配电网优化控制的一种有效途径。文章研究了一种基于无功补偿设备和分布式电源分组协作机制的配电网分布式优化控制策略,将多个无功补偿设备或分布式电源聚合在一起,以基于领导者的一致性协议控制节点电压和交换功率。文章给出了分布式协同控制框架,各分组控制目标及一致性变量的选取,并证明了各控制组分布式控制算法的收敛性。通过IEEE14节点系统的仿真算例验证了所提出方法的正确性和有效性。     

以SCADA系统为基础的变电站无功电压闭环优化控制

随着无人值班变电站的不断增加,变电站综合自动化系统也在不断完善,功能亦不断强大.为了实现全电网的无功优化控制,提高系统运行的可靠性和经济性,最好的无功控制方式为集中式控制,即调度中心对各个变电站的变压器的分接头和无功补偿设备进行统一的控制.     

Optimization of a photovoltaic pumping system based on the optimal control theory

This paper suggests how an optimal operation of a photovoltaic pumping system based on an induction motor driving a centrifugal pump can be realized. The optimization problem consists in maximizing the daily pumped water quantity via the optimization of the motor efficiency for every operation point. The proposed structure allows at the same time the minimization the machine losses, the field oriented control and the maximum power tracking of the photovoltaic array. This will be attained based on multi-input and multi-output optimal regulator theory. The effectiveness of the proposed algorithm is described by simulation and the obtained results are compared to those of a system working with a constant air gap flux.     

采用室内热舒适性控制的变风量空调系统节能控制研究

在对变风量空调系统及控制系统分析的基础上,利用ＤＤＣ控制器可采集多点和多种信号的优点,提出采用室内热舒适性控制取代室内温度控制的控制方案。仿真试验结果证明,同常规的室内温度控制方案相比,室内热舒适性控制方案可以较好地改善室内的热舒适性,同时,在保证室内热舒适性前提下,采用室内热舒适性控制方案不仅能够保证控制的稳定性,而且有较好的节能作用。     

基于微分跟踪器光伏最大功率跟踪优化控制

光伏发电是一非线性系统,针对光伏系统易受电网工作方式和工作环境的影响,在分析电导增量法的基础上,利用MATLAB/Simulink搭建了光伏阵列数学模型,针对传统电导增量法存在跟踪速度慢及误判的问题,采用微分-跟踪器方法,对电导增量法进行改进优化。仿真结果表明,采用微分-跟踪器改进后的电导增量法能够快速、准确地跟踪光伏系统最大功率,能够有效抑制各种扰动,减少了误判几率,系统的动态性能及稳定性都优于常规电导增量法,从而提高了系统的鲁棒性。     

考虑分时电价的煤矿运输系统改造分析

介绍了生产流程中影响负荷转移的重要因素,分析了生产流程中的负荷构成,并考虑分时电价因素,建立了负荷转移模型。将该模型成功应用到煤矿传输系统中,借助分时电价,帮助煤矿企业合理转移负荷,避开峰时电价,达到节约用电成本的目的。     

一维最优直肋的肋效率分析

为研究等截面一维直翅优化问题,从Schmidt最优翅片形状假定出发,通过理论分析得到一种优化的直翅周线表达式,并找出了优化后的翅片散热效率与其几何外形之间的关系。在优化后的直翅精确解基础上,针对实际工程设计中,在散热效率与精确解偏差不大于0．12％的情况下,进一步推导出翅片所能采用的近似周线方程,为等截面直翅的工程优化设计和应用提供了依据。     

Line-to-line short-circuit-based finite-element performance and parameter predictions of large hydrogenerators

A two-dimensional (2-D), time-stepped finite-element (FE) method is used to model and successfully replicate saturated line-to-line and three-phase short-circuit test responses recorded on a 40-pole 13.75 MVA hydrogenerator at Hydro-Quebec's Rapides-des-Quinze generating station. Three levels of line-to-line and sudden three-phase short-circuit tests (0.13, 0.25, and 0.48 p.u.) are simulated numerically using the FE-based model. While symmetrical faults are only used for parameter determination, the computed line-to-line waveforms are thoroughly compared to real data, with special attention given to field current responses. According to IEEE Std.-115-1995, the d-axis dynamic reactances and time-constants are computed from three-phase short-circuit tests while the negative-sequence reactance is derived from the line-to-line short-circuit test resulting in a rated armature current. The obtained simulated tests responses and parameter values, from both symmetrical and asymmetrical faults, support the effectiveness of the proposed FE-based model in incorporating the saturation phenomenon, large number of poles, and detailed damper representation to achieve an accurate dynamic performance assessment together with negative-sequence reactance and dynamic constants prediction.     

Hamiltonian structures in optimal control theory

The concept of a piecewise smooth Hamiltonian system, motivated by optimal control theory, is introduced and developed. It is proved that the Poisson bracket of two integrals of such a system is globally continuous. Integrable piecewise smooth systems are proved to be equivalent to smooth integrable systems.This research was partially supported by the Russian Foundation for Fundamental Research, grant No. 93-012-470     

Implementation and laboratory test results for an adaptive powersystem stabilizer based on linear optimal control

Implementation of an adaptive power system stabilizer (PSS) based on linear optimal control is described. The generator is identified in real time, and a special third-order discrete Riccati equation is solved in each sample interval. Because the output of the generator is fed back directly, the controller can track the system very fast. Experimental studies on a physical model of a micromachine alternator connected to a constant voltage bus through a transmission line are reported. The PSS was implemented using a multiprocessor architecture employing separate processors for identification, control, and man-machine interface. The various parameters are tuned to obtain the best performance under various disturbances. Test results show that the proposed PSS is very effective in damping out the system oscillation     

Geometric structure-preserving optimal control of a rigid body

In this paper, we study a discrete variational optimal control problem for a rigid body. The cost to be minimized is the external torque applied to move the rigid body from an initial condition to a pre-specified terminal condition. Instead of discretizing the equations of motion, we use the discrete equations obtained from the discrete Lagrange–d’Alembert principle, a process that better approximates the equations of motion. Within the discrete-time setting, these two approaches are not equivalent in general. The kinematics are discretized using a natural Lie-algebraic formulation that guarantees that the flow remains on the Lie group SO(3) and its algebra . We use the Lagrange method for constrained problems in the calculus of variations to derive the discrete-time necessary conditions. We give a numerical example for a three-dimensional rigid body maneuver.      

冷冻水系统优化控制方法

介绍了确定冷冻水系统优化控制的两种方法:基于设备的优化和基于系统的优化。处理优化问题的手段,如二次费用和线性输出,独立控制变量的确定等,对于冷冻水系统的优化控制具有一定的借鉴意义。     

轴流转桨式水轮机组模块化建模研究

以浙江省某水电站双调节轴流式转桨式机组为例,基于SCT3000仿真平台,按模块化建模的基本原则和方法将水轮发电机组层层剖分为若干相对独立又相互联系的模块,并对本体部分建模,研究了双调节水轮机导叶和桨叶协联及非协联时的运动规律,采用图形化模块构建了数学模型,实现了模块化建模.     

基于经济模型预测控制的多虚拟电厂两阶段协调优化调度

在考虑新能源出力具有不确定性的条件下,如何实现多虚拟电厂经济优化运行是当前研究的热点.本文提出了基于经济模型预测控制的多虚拟电厂日前日内两阶段协调优化调度方法.首先,建立了包括风电机组和燃气轮机的分布式电源模型及储能电池模型,设计了参与需求响应的可中断负荷模型;接着,以最大化多虚拟电厂收益为目标,基于改进经济模型预测控...     

轴流转桨式水轮机抬机现象处理

针对满天星水电站轴流转桨式水轮机组抬机现象,从理论上分析了抬机原因,并结合试验和现场处理经验提出了消除抬机现象的防范措施,对确保电站安全运行有指导意义,可供同类工程借鉴.