This paper introduces a system of harmonic analysis,which applies quasi-synchronous sampling arithmetic and DSP.Two processors is used in the system.The main processor(MCU) is for man-machine interface and the bootloader of DSP.The coprocessor(DSP) achieves data processing.By defining float data on fixed-point DSP,accuracy is improved.And with application of quasi-synchronous sampling arithmetic,high precision harmonic analysis is realized when there would be a non-synchronization between the sampling period and the signal period.The system has been applied in optoelectronic high-voltage measurement set.The accuracy of fundamental wave and harmonic wave(3rd-11th) is better than 0.1% and 2%.The system has practical value and expansibility.

This article introduces a style of kilowatt-hour meter of high voltage which adopts optoelectronic current transformer. The suspended power source is designed to accommodate the power supply on high voltage site. High-speed and low-power consumption MPUs are used to achieve electric energy measuring on high voltage site. Hence it can prevent the electricity-theft activities efficiently. The quasi-synchronous sampling arithmetic is applied to solve the problem of electric energy measuring on periodicity aberrance wave. The experiment indicates that the proposed kilowatt-hour meter is practical and its accuracy is high.

基于DSP的电子式高压电能表是新一代的多功能高压电量计量仪器,与以往电网二次侧计量设备不同,它采用高、低压侧分体式结构,在高压侧计量电能值,在低压侧的高速DSP中计算电压、电流有效值等各相电网参数,并且具有电压、电流谐波分析的功能,同时利用高绝缘的光纤进行通讯,通过液晶显示各项参数,具备很好的防窃电功能.

In this paper a project for the design of an opto-electronic current transformer (OECT) is presented, in which the optical fibre is used as the insulation between the high voltage side and the low voltage side and at the same time the fibre is applied to carry out the digital communication between the both sides. The kernel device of the project is digital signal processor (DSP) which can perform high speed floating-point operation, otherwise, the optical fibre technique, the communication technique and the micro-computer technique are adopted. The current measurement and harmonics analysis are integrated in OECT and the interface circuits for both computer communication and protective relaying are also provided. Test results show that the OECT possesses following features: simple structure, easy to install, high counter-interference capability and high measuring accuracy.

0　引言 随着电网商业化运营和用电营业管理现代化的需要，电能表的多功能化和自动化将成为实现这种改革的一种重要的技术手段。光电式高压电能表应用于10 kV配电系统，可以实现电能的直接高压计量，从根本上解决了长期困扰电力系统的窃电问题，为实现配电网的高压计量收费奠定了技术基础。 该表应用光电式电流互感器这一新型电子元件，采用了先进的DSP技术及网络技术，将这些技术与微机有机地结合起来，能完成有功电能、无功电能、有功功率、无功功率、视在功率、频率、电压、电流、功率因数等数据的实时计量与监测，不仅具有复费率电表的高、谷、平分时计量功能，同时具有计量配电变压器损耗、谐波电能及基波电能的功能，还可实现远程读表、负荷监控、电费分时统计结算等功能，从各方面满足了电能量计费系统的要求［1］。本文主要从系统设计角度，介绍在光电式高低压电能表(OEWM)系统中，高速DSP芯片TMS320C542的设计应用。

In order to meet the requirements for small size, automation and high reliability of protection and monitor equipment in electric power system, an Optoelectric Current Transformer(OECT) is designed. The OECT consists of optic fiber, communication unit and microcomputer, and it can be applied to current measurement, harmonic wave analysis and power measurement. The trial run in power network demonstrates that the OECT has the advantages of wide dynamic measuring range, fast response speed and resistance of electromagnetic interference.

A new optoelectronic current transducer (OECT)is developed,which can measure current,voltage,active power,reactive power and power factor.Furthermore,the OECT provides power system protection function and can interface with a computer.

新型电力系统故障录波及定位系统是记录输电线路故障信息的智能自动化仪器,该仪器集工控机、GPS(全球卫星定位系统)、高速数据采集卡、DSP(数字信号处理器)于一体,利用虚拟设备驱动程序(Vxd)和多线程技术,提供Windows操作平台,具有全网同步高速大容量的数据采集、录波监控及定位功能.

介绍了一种应用于高压测量系统中电源方案,可成功地解决高压侧电子测量设备的电源问题与对地绝缘之间的矛盾.该方案已应用于10 kV光电式电流互感器中,取得了良好的运行效果.

A new current measurement method combines Rogowski wiring with a voltage frequency convector (VFC) was discussed to offer a very accurate current measurement for large currents. Since the output voltage of Rogowski wiring is proportion to the differential of the input current and the VFC result is proportion to the integral of the input voltage, a nonlinear integral circuit is not needed. The paper shows that for the proper integral interval, the harmonics in concern can be reserved and some noise can be filtered. A very accurate optical electric current transformer (OECT) was developed using this method in the 10A～5kA current scale.

介绍一种新型的快速高准确度开方算法,特别适用于需要用计算机进行(√a2+b2)型式开方运算场合.算法巧妙地将开方变量由两个减少为一个,将变量变化区间由整个实数轴缩小为[0,1]区间,进而采用查表与插值相结合的方法,实现了高准确度、快速开方运算.在单片机80c196kb上,利用PL/M96语言编程进行了运算,效果良好.

This article introduced a kind of pleisiochronous Discrete Fourier Translation (DFT) algorithm to realize the high precision harmonic analysis when there would be a non synchronization between the sampling period and the signal period. First, the paper proposed the high precision equalizing value calculation process of the periodic functions by using the pleisiochronous algorithm when the sampling would be non synchronous. Then through a newly constructed function, the Fourier translation process was converted to the solution procedure of an equalizing value of a periodic function. Further more, the quasi synchronous algorithm and Fourier translation algorithm were integrated. After the discretization, the high precision harmonic analysis algorithm routine, which would be suitable for computer processing, was obtained under non synchronous condition. The simulating test shows that the accuracy of the integrated algorithm is higher than that of DFT by one order. When the deviation of the sampling periods is less than half period and the sampling number required by the sampling theorem is satisfied, after properly selecting the parameters of the algoritm, the measuring accuracy of nearly “perfect synchronized sampling” can be got.

Longitudinal differential protections for electric main equipments (transformer, generator, motor, busbar, etc. ) misoperate frequently under normal operation, and the same misoperation occurs over and over again. "Cause is not clear" is often the conclusion. This paper analyzes the transient performance of current transformer in the protective level. It is pointed out that TP class current transformer is too expensive for medium and low voltage device, and also difficult to install because of its bulky size. Digital optical current transducer (DOCT) has been developed successfully, which provides possibility to solve the said problems.

The characteristics of optic fiber current transducer are introduced. Compared with the traditional transducer, it has higher measuring precision, better transient characteristic, simpler insulation structure, smaller size, lower cost and better scalability. Optic fiber current transducers can be divided into two groups: opto-electronic current transducer (OECT) and magnetic optical current transducer (MOCT). The principles and structure characteristics of these two types of optic fiber current transducers are presented. It has broad prospects to apply the optic fiber technique integrated with computer technique in the power systems, in particular, in the integrated substation automation system.