Parameter identification of electrical power quality by a new synchronisation method and an innovative measuring instrument

The measuring and analysing of the quality and efficiency of electrical power usage is an important topic today and in the future. Electrical energy measurement must be synchronised with power frequency to analyse integer cycles and provide accurate power quality analysis. In this paper a new synchronisation method is presented which is realised from the software side without using PLL (Phase-Locked Loop). The paper also deals with real-time data processing, which is achieved with a multi-core personal computer (PC). In this way the power of the modern PC can be exploited in the area of electrical energy measurement. A measuring device was developed to implement the new synchronisation method and exploit the power of multi-core CPUs.     

Estimation of time-varying power quality indices using a computationally efficient algorithm

In this paper a new recursive adaptive filter based on a fast Gauss–Newton method has been proposed for the estimation of power quality (PQ) indices for time-varying voltage and current signals in an electric power system. The presented algorithm is based on the minimization of a weighted forgetting factor based error cost function by the use of Recursive Gauss–Newton method. Further a Hessian matrix approximation is used to produce a fast recursive algorithm, which is immune to random noise, waveform distortion and increases the speed of convergence and accuracy. The algorithm models the typical time-varying signal and the accompanied distortions due to harmonics and random noise in a manner that will be suitable for real-time PQ indices estimation. Further, the forgetting factor is tuned in accordance with signal error covariance to provide improved performance. Also power system frequency variations are estimated and correction factors are derived. The effects of sub harmonics, and interharmonics in the signal have been considered while estimating the various PQ indices.     

Development of DSP-based instrumentation for power quality monitoring on ships

The paper is to present the new DSP-based device shown in the wake of hitherto development of power quality instrumentation for power quality assessment in ship systems. The motivation of the research is presented and problems of power quality assessment in ship systems is discussed. The basic features of the new power quality estimator–analyser are described. Further, the design of its new commercial, expanded version is shown and discussed.     

Issues in the characterization of power quality instruments

This paper analyzes some issues related to the metrological characterization of instruments for power quality monitoring, in order to move a step toward the definition of a full performance verification protocol. This protocol should include not only the test situations reported in corresponding standards, but also an array of different voltage and current fluctuations – linked to common power quality issues – that may be encountered in actual power systems. This performance analysis is particularly interesting because it can be found that different power quality instruments, fully meeting characteristics prescribed in standard, still may significantly disagree in some actual measurements. This is due for the existence of unresolved technical and theoretical issues related to the metrological characterization through the classical approaches of these instruments. The aim of the discussion carried out in this paper is also the specification of requirements of a test system devoted to calibration and verification of a power quality monitor, such as it is done in type testing. After a preliminary discussion about technical and theoretical issues related to the performance analysis of these instruments, a proposal of test protocol definition, with reference to some power quality phenomena and based on the design of experiment, is presented.     

DSP在电能质量补偿器中的应用

讨论了DSP器件TMS320F240在电能质量补偿器(SPQC)中的应用，重点介绍用该器件实现物理硬件和控制软件方面的实际开发。     

电子式多功能电度表的可靠性设计

电力工业的快速发展，对电能计量仪表的可靠性提出了更高的要求。本文简要介绍了电子式多功能电度表的工作原理、性能特点；详细从供电、测量、保护、监控四个环节叙述了多功能表的可靠性实现方法。     

潜油电机软启动控制器设计

提出一种用双向晶闸管调压的数字移相控制方法，分析了讨论了该方法的工作和设计原理，采用80C196单片机和GAL16V8可编程逻辑器件构成的数字移相触发系统，将该系统用于全数字交流电动机软启动和节能控制的试验结果证明该系统切实可行。     

Method, algorithm and device for estimation of components above the harmonic frequency range up to 9 kHz

The paper presents a method of estimation of frequency groups with 200 Hz bandwidth in the frequency range from the 50th harmonic up to 9 kHz. The method consists of the application of a fast Fourier transform (FFT) for wavelet coefficients after input signal decomposition and partial synthesis for chosen frequency bands. It enables the computational complexity of the algorithm to be reduced and also attenuates influence of the fundamental component and low-frequency harmonics, as required by IEC Standard 61000-4-7. The particulars of this method are shown and analysis for a chosen wavelet family is provided. Further, the algorithm and its implementation in real device for power quality monitoring is presented. Finally, the results of measurements of two testing signals are shown. The required attenuation of fundamental component and required accuracy was obtained.     

Capacitive measuring system for two-phase flow monitoring. Part 1: Hardware design and evaluation

Two-phase flows are commonly found in many industrial applications, such as oil and gas production. The monitoring of such flows is performed either in field applications or in pilot plant studies. In both cases, simple and robust measuring techniques are required. Capacitive probes have been applied for void fraction measurement in pipes in research and industry. However, capacitive measuring systems applied so far are tailored for specific applications and may not be easily adaptable. In addition, more and more soft-computing methods are applied for advanced data processing and parameter extraction which requires more computational power of sensor systems for online data processing. We develop a capacitive system provided with a microcontroller in which necessary routines for data processing may be embedded. System design is detailed explained and system's performance is evaluated, showing appropriate accuracy and time response for the investigation of two-phase flows.     

基于DSP的电能质量在线检测装置的研究

设计一种基于DSP的电能质量在线检测装置。为达到电量采样和分析同步进行。一方面采用TMS320C5509作为处理器。另一方面通过CPLD来完成系统的逻辑控制;为把检测装置的分析结果可靠地传输给远方的控制分析中心,采用了目前工业控制中比较成熟的CAN通讯方式。     

Gearbox power loss. Part III: Application to a parallel axis and a planetary gearbox

In the third part of this work, the rolling bearing torque loss model, the lubricant factor extracted from the FZG tests with wind turbine gear oils and the loss factor for helical gears, developed in Part I and Part II of this work, will be applied to predict the power loss in a parallel axis and a planetary gearbox. The numerical results obtained are compared with those from experimental tests.     

质量管理与质量控制现状及研究方向

分析了当前质量管理和质量控制的现状 ,针对先进生产模式和信息技术 ,以及相关技术的质量管理和质量控制研究方向进行了详细的探讨。     

Power quality impacts of high-penetration electric vehicle stations and renewable energy-based generators on power distribution systems

High-penetration renewable energy-based generators (REGs) in distribution systems have increased the importance of impact assessment involving these systems. This assessment focuses on power quality (PQ) and compatibility between REGs and existing system components. Electric vehicle (EV) technology has also recently achieved a substantial market share. This technology requires the development of charging stations similar to current petroleum fuelling stations in the near future. Thus, the effect of EV stations (EVSs) on PQ must also be considered. This study presents a PQ analysis on the effects of high-penetration EVS and REG systems, including wind turbines, grid-connected photovoltaics (PVs), and fuel cell (FC) power generation units on a modified 16-bus distribution system under different loading and weather conditions. All data on EVS, wind farm, PV, and FC units as well as weather conditions presented in this paper were collected from different power companies and the Malaysian Meteorological Department. The system is modelled and simulated using the MATLAB/Simulink software to study the effects of these technologies on system performances at various penetration levels. Simulation results indicated that the presence of high-penetration EVSs and REGs can cause severe PQ problems such as frequency and voltage fluctuations, voltage drop, harmonic distortion and power factor reduction.     

A few remarks about assessment methods of electric power quality on ships – Present state and further development

This paper concerns the problem of reliable assessment of a power quality in naval networks. Two aspects of the problem were discussed. Firstly, the parameters for electric power quality assessment and their permissible levels were presented. Further, the methods of their measurement were analyzed. Especially the critical analysis of relevant IEC standards was presented and proposals for their amendment were laid. These considerations were based on the results of the original author’s research carried out in ship electrical power systems for a few years. Finally, the original and complete methods of signal processing and basic features of newly constructed instrumentation for power quality assessment were shown. Presented paper is a continuation and in some respect the synthesis of the earlier works prepared by the same author completed by new contribution.     

汽车总装配生产线质量实时统计和控制系统的设计与开发

针对汽车总装配生产中重要螺纹连接的质量控制问题,将现代质量控制和管理的思想方法与计算机网络信息系统相结合,根据生产实际的信息收集、整理和传递过程,建立基于Ethemet的统计质量控制信息系统实时控制总装配质量。     

行星齿轮功率分流式无级变速器的设计研究

针对液力自动变速器传动效率低、油耗大、结构复杂的缺陷,提出了一种新型的行星齿轮功率分流式无级变速器,它取消了液力变矩器,在辛普森双行星排变速机构的基础上,通过功率分流并调节发电机输入功率来实现无级变速,该变速器结构简单,传动效率高,具有较高的实用价值。     

An improved approach for robust control of dynamic voltage restorer and power quality enhancement using grasshopper optimization algorithm

This paper presents a novel contribution of a low complexity control scheme for voltage control of a dynamic voltage restorer (DVR). The scheme proposed utilizes an error-driven proportional–integral–derivative (PID) controller to guarantee better power quality performance in terms of voltage enhancement and stabilization of the buses, energy efficient utilization, and harmonic distortion reduction in a distribution network. This method maintains the load voltage close to or equal to the nominal value in terms of various voltage disturbances such as balanced and unbalanced sag/swell, voltage imbalance, notching, different fault conditions as well as power system harmonic distortion. A grasshopper optimization algorithm (GOA) is used to tune the gain values of the PID controller. In order to validate the effectiveness of the proposed DVR controller, first, a fractional order PID controller was presented and compared with the proposed one. Further, a comparative performance evaluation of four optimization techniques, namely Cuckoo search (CSA), GOA, Flower pollination (FBA), and Grey wolf optimizer (GWO), is presented to compare between the PID and FOPID performance in terms of fault conditions in order to achieve a global minimum error and fast dynamic response of the proposed controller. Second, a comparative analysis of simulation results obtained using the proposed controller and those obtained using an active disturbance rejection controller (ADRC) is presented, and it was found that the performance of the optimal PID is better than the performance of the conventional ADRC. Finally, the effectiveness of the presented DVR with the controller proposed has been assessed by time-domain simulations in the MATLAB/Simulink platform.     

电网电容电流外加信号单频测量法的研究与应用

针对高压电力系统发生单相接地时,流经故障点的电流急剧增加,产生很强的间隙弧光接地过电压问题,对电网电容电流外加信号测量控制器的方法进行了详细的分析,充分论证了测量电网电容电流的必要性,对电网电容电流外加信号单频测量控制器的方法进行了研究,将外加信号单频测量法的原理计算分析与其他测量方法进行了比较。研究结果表明,电容电流外加信号单频测量法具有测量准确,特别是电网系统阻尼大,回路Q值低或位移电压很小时,更能显示外加信号单频测量法的优势,为进一步进行优化电网电容电流测量法的设计与应用奠定了基础。     

Elastodynamic analysis of a gear pump. Part II: Meshing phenomena and simulation results

A non-linear lumped kineto-elastodynamic model for the prediction of the dynamic behaviour of external gear pumps is presented. It takes into account the most important phenomena involved in the operation of this kind of machines. Two main sources of noise and vibration can be considered: pressure and gear meshing. Fluid pressure distribution on gears, which is time-varying, is computed and included as a resultant external force and torque acting on the gears. Parametric excitations due to time-varying meshing stiffness, the tooth profile errors (obtained by a metrological analysis), the backlash effects between meshing teeth, the lubricant squeeze and the possibility of tooth contact on both lines of action were also included. Finally, the torsional stiffness and damping of the driving shaft and the non-linear behaviour of the hydrodynamic journal bearings were also taken into account. Model validation was carried out on the basis of experimental data concerning case accelerations and force reactions. The model can be used in order to analyse the pump dynamic behaviour and to identify the effects of modifications in design and operation parameters, in terms of vibration and dynamic forces.Part I is devoted to the calculation of the gear eccentricity in the steady-state condition as result of the balancing between mean pressure loads, mean meshing force and bearing reactions, while in Part II the meshing phenomena are fully explained and the main simulation results are presented.