Kalmen estimator as a robust solution for output power maximization of wave energy converter

In this paper, the application of linear quadratic Gaussian (LQG) control for a buoy‐type point absorber of a wave energy converter (PA‐WEC) system is investigated. The proposed wave energy conversion is considered as a two‐body system, which is taut‐anchored to the sea floor using three cables. The main goal of this study is to extract the maximum available power from the ocean wave. This is accomplished via determining the optimal value of the force exerted on the power take‐off (PTO) system taking in account the physical constraints on the position and velocity. First, the reduced nonlinear dynamical model of the WEC system is obtained. The nonlinearity in the mooring force is replaced by a linear law to yield the state space linear model of the system. Then, the standard Kalman filter technique is employed to estimate the full states of the system. Based on the LQG control approach, the optimal PTO force is computed at which the maximum output power can be easily harvested. The computational burden is minimized to a great extent by computing the optimal state feedback gains and the Kalman state space model offline. The feasibility of the proposed control approach in extracting the optimal power of the ocean wave is validated via the simulation example even under different values of the mooring constant and without violating the system limitation. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

A factored form of the instrumental variable algorithm

A UDV^T-factored form of the instrumental variable (IV) identification algorithm is developed for identification of systems with coloured noise. The algorithm uses a UDV^T factorization technique to reformulate the conventional instrumental variable method and simultaneously produces the parameter estimates and loss functions for all models from order one to a user-specified number n with approximately the same computational effort as the conventional IV algorithm. The algorithm possesses a unique compact structure that facilitates the interpretation and implementation of IV-type algorithms. The UDV^T factorization technique used in this algorithm also results in better numerical performance than the conventional instrumental variable method.     

一种多模式变频宽输出LLC变换器

针对新能源领域对开关变换器具有宽电压增益范围的要求,提出一种多模式变频宽输出LLC变换器.该变换器原边为全桥结构,副边整流器为两级倍压结构,通过控制副边开关管的导通与截止,具有3种不同的电路模式,其增益比为1:2:4.各种模式对应不同的输出电压等级,采用变频控制方式,变换器可以实现50～430 V的宽输出电压范围.多种...     

空间矢量PWM多相变频调速系统非正弦供电技术

针对多相感应电机正弦供电时直流母线电压利用率低、输出转矩小的问题,建立了多相感应电机非正弦空间电压矢量PWM(NSVPWM)的数学模型,分析了NSVPWM与谐波注入PWM的内在联系,探讨了NSVPWM各个d-q平面参考电压矢量给定问题.以一台九相集中整距绕组感应电机为例,在保持齿、轭部磁密幅值分别相等、定子铜耗相同的前提下,将其分别在SPWM、正弦空间电压矢量PWM和NSVPWM调制策略下的输出转矩进行比较.试验结果证明,采用NSVPWM控制策略时,九相集中整距绕组感应电机输出转矩比采用SPWM时提高了大约6.42%,最后分析了其原因.     

一种交错级联多模式变频宽输出LLC变换器

新能源领域要求开关变换器具有宽增益范围、高效率和高功率密度的特点.论文针对新能源电动汽车充电系统,提出了一种基于交错级联结构的多模式变频宽输出LLC变换器.该变换器原边为双半桥交错结构,副边整流器为上下级联结构,通过控制原边交错模式和副边开关管的导通与截止,具有4种不同的电路模式,其增益比为0.5:1:1.5:2.电路...     

Coupling heat storage to nuclear reactors for variable electricity output with baseload reactor operation

Nuclear reactors produce heat and thus can couple to heat storage systems to provide dispacthable electricity while the reactor operates at full power. Six classes of heat storage technologies couple to light-water reactors with steam cycles. Firebrick Resistance-Heated Energy Storage (FIRES) converts low-price electricity into high-temperature stored heat for industry or power. FIRES and brick recuperators coupled to nuclear brayton power cycles may enable high-temperature reactors to buy electricity when prices are low and sell electricity at higher price.     

State smoothing in Markov jump systems with lagged mode observation

Estimation involving Markov jump systems (MJSs) is widely used in target tracking, speech recognition and communication. It is assumed in MJSs that state measurement and mode observation are synchronous. In applications such as image‐based target tracking, the target orientation, as one of the mode observations, needs additional computation time for pattern recognition and thus can be delayed. This motivates us to explore the smoothing problem of MJSs with mode observation lagged to state measurement. This brief paper presents a recursive estimator by deriving the conditional state mean and the conditional model probability from both delayed mode observation and state measurement. Simulations on maneuvering target tracking are carried out to validate the performance of the proposed smoother in comparison with existing methods. Copyright © 2010 John Wiley & Sons, Ltd.     

液位系统的辅助变量复合建模方法研究

针对发电过程控制策略设计和计量方法研究过程中,对系统模型要求越来越高的现状,基于辅助变量最小二乘(RIVLS)辨识方法,提出一种分别以一阶惯性加纯滞后模型(FOPDT)和二阶惯性加纯滞后模型(SOPDT)为基本组成部分,以建模误差的均方差为加权因子的复合建模方法,并通过实验室液位系统建模仿真过程,证明新算法的有效性。仿真结果表明:该方法具有提高建模准确性的作用,该建模方法可以扩展应用于其它对模型精度要求较高的生产过程中。     

风电出力变化对系统调频的影响

随着大规模风电的并网,需要研究风电出力波动和系统调频速度的关系,探讨大规模风电并网对系统调频的冲击。通过对张家口地区单个和多个风电场的调度EMS数据进行统计分析,验证了风电出力变化率呈正态分布,随着所统计风电场容量的增加风电出力变化率降低的特性,并得到了风电场出力变化率的数值范围,结合甘肃电网的系统调频速度数据,对风电接入率、风电出力变化率和系统调频速度的关系进行定性计算分析,得出了系统调频速度并非限制风电大规模接入制约因素的结论。     

An adaptive estimation method using instrumental variables and deconvolution

The performance of the methods of recursive instrumental variables (RIV) and minimum variance deconvolution (MVD) is examined when the methods are interwoven so as to provide adaptive estimation of the ARMA model parameters of a system driven by white unmeasurable noise. It is shown that the methods have some similar properties which permit their successful combination in most cases. The asymptotic properties of the resulting estimation approach are evaluated in terms of the ARMA model parameters or the pole-zero locations, the signal-to-noise ratio and the frequency bandwidth of the system impulse response. An analysis of the second-order ARMA model and various simulation examples are presented which illustrate the derived results. The method has been successfully applied to the problem of adaptive seismic signal deconvolution.     

An automated monitoring system as an instrument of lean production of a traction power supply system

Issues of using an automated monitoring system for implementation of the principles of lean production in the traction power supply system of Russian railways are considered. As a result of analysis of the operational efficiency of existing systems of monitoring of railway infrastructure facilities from the point of view of the principles of lean production, unused capabilities of the monitoring systems were revealed. It is suggested to take advantage of these unused capabilities independently or in combination with other components. The efficiency of application of the suggested solutions is proven due to reduction of time for repair work, an increase in overhaul periods, an increase of reliability of the traction power supply system, and making the work time more effective of the maintenance personnel. The necessity of combining the principles of lean production is justified not only with the information monitoring systems, but with other modern management approaches and practices. Use of lean production technologies will permit reduction in the time for repair works, an increase in the overhaul periods, an increase in the reliability of the traction power supply systems, an increase in the efficiency of the work time of maintenance personnel. It can be expected that it will lead to a significant decrease in the range of repair work (will exclude the repair of units without defects) and an increase in the overhaul period. As a result, lean production will permit using smoothly not only the information monitoring system, but also other modern management approaches and practices.     

一种变权重风电功率最优组合预测模型

针对单项预测方法的局限性,利用改进的基于灰色关联度的IOWGA算子组合预测模型,建立了一种风电功率最优组合预测模型,并通过改进多种群遗传算法(MPGA)对该模型进行优化。采用RBF神经网络法、相似日法和支持向量机(SVM)法对预测日和预测日前一日的风电功率分别进行预测,通过提出的最优组合预测模型及优化算法对预测日的24 h风电功率进行组合预测。根据云南某风电场的实测数据,进行了实例分析。结果表明,风电功率最优组合预测模型能够有效提高风电功率预测精度,具有较强的实用性。     

Operating experience with the AEP state estimator

Some of AEP's (American Electric Power) state estimator experience over a period of thirteen years is reported. The scenarios of several unusual system events are described. Justification for a new estimator, which has been in service for nearly three years and can accommodate measurements other than line flows, is provided. The AEP metering system and specification of measurement weights which support the estimator have been explained. Some recommendations for new features in the state estimator package are given     

基于CAN总线和虚拟仪器技术的变频调速实时监控系统*

本文研究了变频调速实时监控系统的开发方法。利用控制现场总线(Controller Area Network,简称CAN),在保证传输速度的前提下,提高了系统的抗干扰能力。为了克服短帧通信所造成的信息量小的缺点,改进了传统的应用层协议,充分利用标识位传输有效信息。以LabVIEW软件为开发平台,通过批量接收、显示数据的方法,克服了上位机显示缓慢的缺点,实现了数据选择、分析、实时显示、录波、触发等功能。该监控系统界面友好,使用方便,同时实现了监视和控制功能,可以广泛应用于变频调速场合。     

Field operational experiences with on line state estimator

This paper presents the field experiences during the process of bringing the state estimation function on line. Several practical problems involving topology, analog telemetry, equipment parameters, system load calculation, pockets of unobservable buses and external equivalent modeling were identified. Implementation of some trial solutions as a part of Pacific Gas and Electric company's (PG&E) Energy Management System is presented