基于PCA-OLS模型的系统等效惯量中长期预测

为综合考虑多重影响因素与系统等效惯量之间的量化关系,本文提出一种基于主成分分析-普通最小二乘法的系统等效惯量中长期预测模型。根据电网实际调度规则搭建简化的开机方式优化模型,构建系统等效惯量中长期预测历史数据集;利用主成分分析对系统等效惯量主要影响因素的多重共线性进行消除,得到主成分表达式;进行多元普通最小二乘法回归,反标准化后得到系统等效惯量解析模型。根据某电网能源发展规划数据,对未来系统惯量水平进行推演,可快速预估不同运行方式下系统等效惯量的演化趋势及非同步电源承载能力。

开环同步型单相并网逆变器小干扰建模与弱电网下稳定性分析

单相并网逆变器中,多采用锁相环(phase-lockedloop,PLL)型闭环同步方法,但PLL引入的低频段负阻特性不利于系统稳定性,在电网阻抗较大时并网逆变器易发生严重失稳。对此,国内外广泛开展了PLL优化或替代技术的研究。其中,开环同步(open-loop synchronization,OLS)方法的无反馈结构使得其自身是完全稳定的,近年来得到了较多关注。然而,OLS结构中非线性特性明显,如何获得准确的小干扰线性化模型仍非常困难,OLS型单相并网逆变器在弱电网下的稳定性仍不清晰。鉴于此,重点研究开环同步型单相并网逆变器小干扰建模与稳定性。借鉴谐波线性化思想,提出OLS的线性化建模方法,建立开环同步型单相并网逆变器的输出阻抗模型。在此基础上,讨论OLS型单相并网逆变器的鲁棒性。较大电网阻抗下,采用OLS的开环同步型单相并网逆变器系统仍有良好的稳定性。通过仿真和对比实验验证上述模型的准确性以及弱电网下OLS的适应性。

Open-loop Phase Synchronization Method of Positive and Negative Sequences for Three-phase Asymmetric Grid

Currently,a grid-connected inverter is required to inject a dual-sequence current during asymmetric grid sags,which means both positive and negative sequence phases should be tracked.This paper proposes an open-loop phase synchronization(OLS)method of positive and negative sequences for an asymmetric grid based on the moving average filter(MAF),which does not need to separate the positive and negative sequence fundamental components of grid voltage.As a benefit,there is no double-frequency oscillation in the estimated phases at offnominal frequencies since the positive and negative sequence phases are obtained simultaneously.The proposed method not only has the inherent advantages of OLS,but also further improves the dynamic response since the window length of MAF is only 1/6 of the fundamental period.The effectiveness of the proposed OLS is verified by experimental results.

Chaos Correlation in Open-loop Semiconductor Lasers Scheme Effected by Variable Feedback Time

The effect of optical feedback time （depend on the distance between the front facet of the laser and the external mirror） on the chaos synchronization in open-loop communication system have been investigated. In this system, the dynamics of semiconductor lasers with both the optical feedback and optical injection are coherently coupled with the internal laser field. The synchronization map becomes a cloud of points for some parameters values （no correlation between Master laser ML and Slave laser SL outputs）. It means that the two lasers are decoupled. It can be clearly seen when kf = 0.2, kinj = 0.4 and τ = 1 the correlation between these two laser outputs are in a diagonal line, which implies the excellent correlation between them and verifies their synchronization. It is evident that the synchronization quality of open-loop scheme improves for this value is better than that of the other amounts. Value is better than that of the other amounts.

SOLVABILITY AND CONTROL DESIGN FOR SYNCHRONIZATION OF BOOLEAN NETWORKS

This paper addresses the synchronization problem of Boolean networks.Based on the matrix expression of logic,solvability conditions and design procedures of the synchronization of Boolean networks with outputs are given for both open-loop and feedback control.Necessary and sufficient conditions on open-loop control are proposed first with a constructive design procedure.Then sufficient condition for the feedback control case is obtained,and corresponding design procedure is proposed with the help of algorithms to solve logic matrix equations.Numerical examples are also provided to illustrate the proposed control design.

基于在线最小二乘支持向量机逆系统的高速永磁同步电机解耦控制

针对高速永磁同步电机(high speed permanent magnet synchronous motor,HS-PMSM)的解耦控制系统,根据逆系统理论分析了其数学模型的可逆性,进一步提出一种基于在线最小二乘支持向量机(online least squares support vector machine,OLS-SVM)的逆系统方法,实现了HS-PMSM的高性能解耦控制。该方法设计了基于OLS-SVM的实时逆系统,并将其与原系统串联构成一种伪线性系统,实现了HS-PMSM系统的线性化和解耦。同时,在HS-PMSM逆控制系统中为获得高精度定子磁链观测,进一步引入一种基于带通滤波器和参数补偿(band-pass filter with parameter compensator,BPFC)的磁链观测器。通过仿真和实验研究,在宽速范围内转速和电流解耦控制、不同转速域转速跃跟踪和负载抗扰性能等几个方面验证了文中所提出的解耦控制方法的有效性。

An Improved Frequency Synchronizer for Mobile OFDMSystems

Orthogonal Frequency Division Multiplexing （ OFDM） system is sensitive to Carrier Frequency Offset （ CFO ）. In this paper, traditional Maximum Likelihood Estimators （MLE） for CFO of OFDM are introduced first. Then, averaging method and a-filter are introduced as Low Pass Filter （LPF） to improve the performance of cyclic prefix estimator. The bandwith of LPF is determined by the coherence time of radio channel. Estimation performance in multipath channel is analyzed. Outlier picking-out scheme is proposed to improve performance further. Performance of close-loop structure is presented briefly, which is worse than that of open-loop structure. Finally, a parallel switch structure of frequency synchronizer is proposed for mobile OFDM systems. The scheme ezcploits training sequence and cyclic prefix. The proposed synchronizer has a wide acquisition range. It is accurate and robust in both AWGN channel and multipath channels. The complexity is low due to functionality of a-filter. A better performance of frequevlcy synchronization is obtained comparing to that of existing Maximum Likelihood Estimator（ MLEs）. We achieve these advantages without loss of bandwidth efficiency.