CS1000在焦炉改造中的应用

叙述了横河CS1000系统在焦炉的应用,对其组成及控制做了详尽的介绍.实际运行证明,顺序逻辑控制正常可靠,设备运转正常.     

自适应模糊H∞控制在导弹自动驾驶仪中的应用

自适应模糊H∞控制在导弹自动驾驶仪中的应用,通过对攻角求二阶导数,得到导弹输入-输出动态模型,同时将模糊系统简变为单输入逻辑系统.设定攻角变化范围,并将其作为模糊系统的唯一输入变量.根据系统的带宽,在控制器中加入低通滤波器,以保证系统跟踪效果,过滤控制信号中频率过高部分.仿真证明,该应用可得到导弹飞行动态的精确数学模型.     

Distributed cooperative synchronization strategy for multi-bus microgrids

Microgrids can operate in both grid-connected mode and islanded mode. In order to smooth transfer from islanded mode to grid-connected mode, it is necessary to synchronize the point of common coupling (PCC) with main utility grid (UG) in voltage frequency, phase and amplitude. Conventional synchronization methods based on centralized communication are very costly and not suitable for multi-bus microgrids that have a large number of distributed generators (DGs). To address this concern, this study presents an active synchronization control strategy based on distributed cooperation technology for multi-bus microgrids. The proposed method can reconnect the microgrid in island to UG seamlessly with sparse communication channels. Synchronization correction signals are generated by a voltage controller, which are only transmitted to the leader DGs. Meanwhile, each DG exchanges information with its neighbors. Finally, the voltage of PCC will synchronize with the main grid and all DGs will achieve the consensus behaviors. Compared with traditional synchronization methods, the proposed method does not need complex communication networks and improves flexibility and redundancy. Even if the distributed communication breaks down, the primary droop control can still operate robustly. Small signal model of entire system is developed to adjust the parameters of distributed active synchronization controller. Simulation results are presented to verify the effectiveness of the proposed method.     

Mismatched disturbance attenuation control for static var compensator with uncertain parameters

The use of a static var compensator (SVC) as a component of flexible alternating current transmission system (FACTS) devices to control power systems has been investigated for decades. Its aim is to regulate the system voltage and improve the stability and loadability of power systems. A typical assumption in such a system is that the parameters of the controlled system are known accurately, which is rarely satisfied in practice. This paper explores the development of a simple but effective controller for a single-machine infinite-bus power system with SVC subjected to both matched and mismatched disturbances where the controller derivation is based on the assumption that all parameters used in the system modeling are unknown, but bounded in size. The research in this paper illustrates how an indirect robust control can be incorporated with a modified disturbance observer-based feedforward term to attenuate the influence of parameter variations and disturbances from the outputs of the system. Simulation results are presented to confirm the effectiveness of the proposed scheme.     

Coordinated voltage control of wind-penetrated power systems via state feedback control

This paper presents an optimal coordinated voltage control scheme for preserving long-term voltage stability of power systems. Linear quadratic integral (LQI) controller is employed to construct this scheme. Also, this paper considers the detailed dynamic model of doubly-fed induction generator (DFIG) wind turbine, synchronous generators, over excitation limiter (OEL) and under-load tap changer (ULTC) system, which are important elements influencing voltage stability of power systems. The proposed approach at each time instance involves following two major steps: First, the power system nonlinear equations are linearized and optimal controllers are obtained by LQI technique. Then, in the second step the system dynamic behavior is investigated via time-domain simulations by applying the attained optimal control signals at the first step. The impact of the proposed coordinated voltage control scheme is evaluated by time domain simulations on a well-known test system, under variable wind speed and fault conditions.     

顶管技术应用中的问题浅析

本论文在简单介绍了顶管技术的施工特点的基础上,重点分析了顶管技术在市政工程建设中的应用,讨论了大量施工中暴露出的共同问题,并提出在施工中可操作的预防性施工措施,对于同类工程进一步提高顶管施工的质量水平具有一定借鉴意义。     

多逆变器下垂协调控制方法综述

下垂控制是微电网中多个分布式发电单元(DG)实现功率协调的重要控制方法。对现有的下垂控制方法进行了归类和综述,将其分成有功-频率、无功-电压下垂控制,电压-相角下垂控制和虚拟同步机控制三类,对这三类方法的基本原理和改进方法进行了介绍,为研究人员开展后续研究提供借鉴和参考。     

异步电机效率优化控制及动态响应研究

针对异步电机效率优化问题,在黄金分割法和模糊搜索控制法的基础上,提出了一种新型混合控制方法。该方法在模糊控制中设计了合理的比例因子和隶属度函数,保证了在初始阶段搜索步长,根据电机工况进行在线调整,减小了电磁转矩的波动。在优化的后半段中接入黄金分割法,有效解决了模糊控制在最优点附近振荡和收敛速度慢的问题,保证了系统的稳定性。同时针对弱磁情况,给出了一种动态电流分配策略以提高系统动态响应速度。仿真结果验证了新型混合搜索法和动态电流分配法的有效性。     

考虑锁相环的双馈风力发电机组无源控制

为了降低大规模变速风力发电机接入电网的运行风险,需要研究风力发电机组的控制策略,增加风电对系统功率振荡的抑制能力。该文通过锁相环实现dq坐标系定向以及输出参考点频率值,考虑锁相环的动态作用建立风力发电机组和电网频率之间的端口受控耗散哈密尔顿(PCHD)模型,根据系统平衡方程求得双馈风力发电机组(DFIG)各个状态变量的期望平衡点,然后采用互联和阻尼分配无源控制(IDA-PBC)方法获得转子电压反馈控制律,从而得到DFIG机侧换流器控制和附加阻尼控制器,以改善系统的低频振荡特性,最后以单机无穷大系统和IEEE4机2区域系统为例验证本文所提方法的有效性。     

基于事件触发的DFIG次同步附加阻尼控制方法

为快速、准确判断和有效抑制双馈感应发电机(double fed induction generator,DFIG)并网经串补输电系统送出发生的次同步控制互作用(sub-synchronous control interaction,SSCI)问题,首先分析了DFIG经串补送出系统SSCI的作用路径,并经数学推导给出了SSCI发生判据。然后,基于该判据,进一步提出了一种基于SSCI事件触发的DFIG次同步附加阻尼控制方法,提出了适用于快速检测需求的次同步频率提取方法;引入了迟滞环节来解决电机参数不确定导致的误判问题,提高方法的鲁棒性;设计了相频特性平滑的带通滤波器,增强了控制方法对频率变化SSCI问题的适用性。最后,进行PSCAD/EMTDC仿真验证,结果表明所提控制方法能够在风速变化、串补度变化及风机参数不确定情况下较好地阻尼SSCI,且由于引入了SSCI事件判断机制,附加控制在未出现SSCI风险时退出运行,不影响风机变流器的主控制功能。与已有的附加阻尼控制方法相比,所提控制方法在较高串补度下仍然具有较好的抑制效果。