基于双CPU系统的小电流接地选线装置的研究

【作者】 马姗姗；

【导师】 潘贞存；

【作者基本信息】 山东大学 ， 电力系统及其自动化， 2007， 硕士

【摘要】 我国中低压配电网中性点广泛采用小电流接地方式,这种接地方式具有供电可靠性高的优点。但发生单相接地故障后,长时间的接地运行极易形成两点或多点接地短路,弧光接地还会引起全系统过电压,因此快速准确地选出接地线路对系统的安全稳定运行以及确保系统的经济性有着相当重要的意义。但是由于故障电流微弱、电弧不稳定等原因,单相接地故障选线长期以来没有得到很好地解决,尽管多年来在选线判据上有了较大发展,但是单一的判据依然难以实现准确选线。本论文针对上述问题,利用模糊数学工具,选取相对完善的不同判据,利用注入法原理,并结合零序电流有功功率(或有功分量)法和基于零序电流暂态极大值的故障选线原理建立模糊模型,设置其隶属度函数及有效区间,并设置权重矩阵,根据系统结构和故障实时数据合成动态的自适应复合判据,通过模糊决策得到最终选线结果。该选线方案能有效弥补单一判据的弊端和不足,由于应用了多种选线判据的复合并考虑其隶属度和有效区间,对选线结果进行实时动态的加权评价,大大提高了正确判断的概率。判据的复杂对选线装置的硬件平台提出了更高的要求,本文设计了基于“单片机+DSP”的双CPU系统的综合选线装置,其中以单片机为核心的管理模块主要功能包括故障检测、选线、人机界面以及串口通信等,以DSP为核心的数据处理模块负责采集、处理36路的注入信号信息和零序电流暂稳态信息。本文详细地介绍了装置的硬件平台和软件流程,并对各功能模块的硬件结构和软件流程进行了详细的阐述。随着自动化水平的提高,配网对选线装置的组网和人机交互功能有了更进一步的要求。本装置中采用内藏T6963C控制器的液晶显示器和含九个轻触按键的小键盘构成了人机界面模块,采用RS232和RS485两种通信接口进行串口通信,分别实现与现场调试机通信和利用103规约实现与上级主机通信。本文详细阐释了人机界面和串口通信的软件设计,为装置实现良好的人机交互和组网功能搭建了软硬件平台,并通过VC软件构建PC机的端口维护,实现现场调试。现装置已通过实验室初步试验。更多还原

【Abstract】 The non-solidly earthed system with the advantage of high reliability has been widely used in power distribution network. But if single-phase fault occurs, long-time running with fault would probably cause multi-points earthed, and arcing earthed fault could lead the system high voltage. So the fast and accurate fault line selection has great significance on the safety and stable running of the system. However, for the fault current is very small and the arc is unstable, there hasn’t been a proper approach to solve the fault line selection problem.This paper processed a scenario of fault line selection based on fuzzy logic, which use injection method combined with the criterion based on the incremental of the active component of zero sequence current and the criterion based on transient max of zero sequence current to form a fuzzy logic module. This module is built by the designing of membership function and effective coverage of every criterion and then the weighing of the fuzzy sets of the criterions’ results. Then the scenario could achieve final results after the fuzzy decision according to the construction state of the system and the real-time fault data. This adaptive method could overcome the disadvantage of single criterion. It has significantly improved the accuracy by using multiple criterions, the membership function and the weighing of the fuzzy sets.This paper designed a hardware platform based on dual-CPU system to carry out this complicated scenario. Dual-CPU means SCM combined with DSP. So dual-CPU system is formed with two modules centering on SCM and DSP respectively. The management module centering on SCM are mainly in charged of the management of the whole equipment, including fault detection, fault line selection, human-machine interface and serial port communication. The data-processing module centering on DSP are responsible for the processing of the injection signals and zero sequence currents including transient and steady states from 36 feeders of substation. This paper presents the overview designing of the equipment including hardware structure and function and software process. Besides that, every function part of hardware platform has a detailed description of the hardware structure and the software realization.The equipment this paper designed employed the LCD device controlled by T6963C and little keypad to form the interface hardware platform, and used RS232 and RS485 communication protocols to have serial port communication, which used in the communication with debug machine and network respectively. For the realization of the good human-machine interface and network capacity, this paper has a detailed illumination of the software designing of the interface and serial port communication And for the port maintaining in the on-site debugging, this paper processes the overview designing of the software platform using VC and also a detailed description of its realization. The equipment this paper designed has been preliminarily verified in the lab.更多还原