Performance Evaluation of Power Oscillation Damping Controller—Firefly Algorithm Based Parameter Tuning

This paper presents the performance evaluation of power oscillation damping controller based on firefly algorithm (FA) parameter tuning. The power system stabilizer (PSS), unified power flow controller (UPFC), and static synchronous series compensator (SSSC) are tuned with FA by minimizing integral time multiplied by absolute error (ITAE) as an objective function. An integrated multi-stage linear quadratic regulator – power oscillation damping UPFC/SSSC has been proposed with precise tuning of control parameters which results in overall states' oscillation damping as compared to other classical methods. It has been observed that the proposed control structure damps the oscillations adequately and is modular in design methodology. The sample power system comprising six areas has been considered to demonstrate the effectiveness of the concept. The software has been developed based on the proposed work by the authors and the MATLAB code has been generated in R2009b version. The states' inter-relation which has been shown with eigenvalues reflects a better regulation and the step response is also validated.     

Robust Direct Power Control Schemes of DFIGs Driven by Variable-speed Wind Turbines

Despite its several advantages, a classic direct power control (DPC) technique of doubly fed induction generators (DFIGs) driven by variable-speed wind turbines has some drawbacks such as high power ripples and variable switching frequency. In this paper, two robust controllers are designed to improve the classical DPC performance without complicating the overall scheme. First, an integral sliding mode controller (ISMC) is designed to regulate the stator active and reactive powers. Two integral switching functions are selected for controlling stator active and reactive powers. The idea of total sliding mode controller is selected to avoid reaching phase stability problem. Second, a diagonal recurrent neural network (DRNN) controller is designed and trained based on DPC. The DRNN has several advantages compared to the classical static neural networks such as recurrence and simple construction. Simple off-line back-propagation algorithm is proposed to train the proposed DRNN. The stability of the proposed ISMC and DRNN controller is proved using the Lyapunov stability theorem. The grid side converter is controlled based on the DPC principle to ensure both constant DC-link voltage and grid side reactive power. The feasibility of the proposed DPC schemes is validated by simulation studies on a 1.5-MW wind power generation system. The performance of the proposed schemes is compared with a conventional DPC scheme under different operating conditions.     

电力系统中长期过程动态仿真的组合积分算法

电力系统中长期过程具有非线性、强刚性的特点,其仿真时间框架长,与电力系统机电暂态过程相比,中长期过程对数值积分算法的数值稳定性、收敛性和计算效率的要求更高。针对此问题,将隐式梯形积分法和多步高阶隐式Taylor级数法进行组合,提出新的组合积分算法。在机电暂态过程采用隐式梯形积分法,在中长期过程采用多步高阶隐式Taylor级数法。算例仿真与分析结果验证了新组合积分算法的有效性和可行性。     

“跳出老城区,重建新东光”——对吉林东光集团长春高新区出口基地建设项目的思考

近年来,许多企业都面临着"退城进园"的问题。在制定企业迁建规划方案时,如何站在更高的起点,用现代理念对企业进行结构调整和流程再造,整体提升企业的核心工艺水平和制造能力,满足企业信息化和工业化的发展需求,是设计院经常遇到的课题。     

CMAC与卡尔曼滤波复合控制AVR的优化研究

电力系统的动态稳定已成为现代电力系统工程中一个关键性问题。同步发电机自动电压调节器(Automatic Voltage Regular, AVR)对于电力系统的稳定发挥着重要作用。为使AVR系统适应更加复杂的工作环境,增强AVR抵抗外界随机干扰和快速跟随输入信号的能力,提出了小脑模型神经网络、积分分离式 (Proportional Integral Differential, PID)控制器和卡尔曼滤波器复合控制的策略。通过对云南某水电厂的一台发电机AVR模型的仿真研究可知:该控制策略对于方波输入信号有很强的跟随能力,系统响应速度快,调节时间短,并且对控制通道和测量通道的干扰有很强的抑制作用。仿真结果充分验证了该控制策略的可行性,有助于电力系统的稳定。     

分布式光伏并网电压和功率因数协调控制策略

为应对分布式光伏并网引起的电压越限和功率因数超标问题,提出了一种改进的分布式光伏并网电压和功率因数协调控制策略。该策略包括电压控制策略和功率因数控制策略,电压控制策略采用优先控制光伏发出的无功功率,当无功容量不足时降低有功功率的方法调节并网点电压;功率因数控制策略控制光伏发出的无功功率以调节用户考核点功率因数。针对2种控制策略分别设计了比例积分控制器,最后通过算例,在RT-LAB仿真环境中验证了所提控制策略的有效性。     

基于SOH及离线数据分段矫正的锂电池SOC估计

锂离子动力电池在电动车辆上应用时,受工况、环境等随机因素影响,SOC具有很强的时变非线性,对电动车辆动力电池SOC估计进行研究具有理论意义和应用价值。安时积分法是目前工程中常用的SOC估计方法,在应用过程中存在的难点是积分过程中累积误差的消除。首先利用电池健康状态估算出电池当前时刻的实际可用容量,作为安时积分法中的除数项,对SOC估计值进行矫正;其次,利用离线数据对安时积分法中的累积误差进行分段消除。仿真结果表明,所提方法比传统的安时积分法具有更高的精度,能够较好地消除累积误差。     

基于电流积分的HVDC系统阀短路故障分类与定位方法

为实现高压直流输电(HVDC)系统阀短路故障的快速有效处理,提出了一种基于电流积分的阀短路故障分类与定位方法。定义六脉动换流器电流路径中的"交流截面""上桥臂截面"和"下桥臂截面",计算出采样窗内流过各截面的电流积分,以其大小关系为判据,区分交流侧相间短路、桥臂短路和直流出线短路3种典型阀短路故障类型;针对桥臂短路故障,进一步计算出采样窗内各交流支路和其对应桥臂支路的电流积分差值,定位故障桥臂。基于CIGRE模型的仿真结果表明,该方法能快速分类与定位阀短路故障,且不受故障时刻、噪声和采样窗长的影响。     

负序及谐波畸变电网电压下双馈风力发电系统的改进直接功率控制策略

由于定子直接连接到电网,电网电压中的负序和谐波分量会严重恶化双馈风力发电机(DFIG)系统的运行性能,导致系统输出总电流三相不对称及谐波畸变、总输出有功功率及无功功率波动等,使得DFIG系统无法安全稳定可靠运行,且输出风电质量下降。同时考虑负序和谐波电网下DFIG系统机侧变流器和网侧变流器的运行状态,以改善DFIG系统总输出电流或功率质量为目标,研究基于二阶矢量积分器(SOVI)的DFIG系统网侧和机侧变流器改进直接功率控制(DPC)策略,改善DFIG系统的运行性能。实验结果验证了所提出的负序和谐波畸变电网电压下DPC策略的正确性及有效性。     

采用原子力显微镜评价集料的微纳观特征

为了研究石灰岩和玄武岩集料的微纳观特征,利用原子力显微镜(AFM)测试了其表面纹理与黏附力,并导入SPSS软件校验了数据的稳定性和区分度,对比分析了石灰岩与玄武岩集料在微纳观特征上的异同.结果表明:AFM可有效测试集料的表面纹理,数据稳定性强,区分度高,但测试集料的黏附力时,数据的随机性大,存在着一定的误差;石灰岩表面纹理粗糙、黏附力峰值较高、分布比较随机,与沥青之间的黏结呈"散点式"分布,而玄武岩表面纹理光滑、具有流纹结构,黏附力峰值较低、分布比较均匀,与沥青之间的黏结呈"整体式"分布.