Transient Capability of Superconducting Devices on Electric Power Systems

Superconducting devices operating within a power system are expected to go through transient overload conditions during which the superconducting coil has to carry currents above the rated values. Designing the coil to remain superconducting through any possible fault scenario can be cost prohibitive, necessitating operation beyond the critical current for short periods. In order to set operating limits and design adequate protection systems for superconducting devices connected to a power system, the region of safe operation of these devices has to be described with general capability curves. Existing standards that define limits for these over-current situations are based on copper winding experience that do not apply to devices with superconducting components because of the highly nonlinear interaction between magnetic fields, operating temperature, and current density in the superconductor, and the rapidly varying material properties at cryogenic temperatures. In this paper, the behavior of superconducting coils during over-currents is discussed and a simplified capability curve is described to help standardize device capabilities. These curves are necessary to aid power system designers in appropriately designing the system and associated protection systems.      

三相异步电动机故障仿真

通过Matlab／Simulink软件搭建三相异步电动机模型,对其过载、堵转、短路、定子匝间短路等典型故障进行仿真分析,给出定子电流的变化特征,为以电流为判据的电动机保护装置设计提供理论依据。     

Arc fault detection scheme for 42-V automotive DC networks using current shunt

Introduction of higher dc system voltage distribution networks, such as the 42-V PowerNet in future passenger vehicles appears to be an unavoidable consequence of meeting the increasing future electrical power demand. Higher voltage electrical distribution networks in vehicles force considerable component and system changes regarding electrical safety and reliability. In the event of an arc fault, e.g., when a wire is pinched or cut, or disengaged terminals under load etc., the resulting current may be significantly lower than the trip current of the protection devices such as fuses and circuit breakers. In these cases either the fault is cleared late (depending on the time/current characteristics of the fuse) or, in some cases the fault may not be cleared at all. A cost effective arc fault detection scheme using input side current shunt was developed, built, and tested with different loads including motor loads to clear both parallel and series arc faults in a 42-V dc network. This paper presents the details of the developed arc fault detection scheme and test results under several fault conditions.     

阻抗保护出口时限异常的原因分析

以温州轨道交通S1线灵昆牵引变电所的一次故障跳闸数据入手,深入分析阻抗保护在特殊情况下动作的时限问题,详细介绍阻抗保护动作数据的人工复核、分析方法,为供电系统管理人员分析保护动作数据提供一套新的思路。     

基于单片机的低压马达保护装置

介绍了一种以单片机MSP430为控制核心的低压马达保护装置,能够实现对低压马达故障进行判断和保护。分析了低压马达在工作时的常见故障和判定依据,及傅里叶算法作为采样算法。设计了以单片机控制系统的硬件电路,能够实现过载、堵转、短路、断相、不平衡等马达故障的功能保护,提出了软件设计程序流程。该装置能够有效且可靠地保护低压马达。     

A 70 mΩ intelligent high side switch with full diagnostics

A new, smart power switch for industrial, automotive, and computer applications developed in BCD (Bipolar, CMOS, DMOS) technology is described. It consists of an on-chip 70 mΩ power DMOS transistor connected in high side configuration and its driver makes the device virtually indestructible and suitable to drive any kind of load with an output current of 2.5 A. If the load is inductive, an internal voltage clamp allows fast demagnetization down to 55 V below the supply voltage. The device includes novel structures for the driver, the fully integrated charge pump circuit, and its oscillator. These circuits have specifically been designed to reduce electromagnetic interference (EMI) thanks to an accurate control of the output voltage slope and the reduction of the output voltage ripple caused by the charge pump itself. An innovative open load circuit allows the detection of the open load condition with high precision (3 mA ±10% within the temperature range from -25 to 150°C and including process spreads). Furthermore, the device protects the load from ground disconnection and is compatible with the new IEC standards concerning burst and surge tests. The quiescent current has also been reduced to 600 μA. Diagnostics for CPU feedback is externally available from the chip by two dedicated pins when the following fault conditions occur: open load, overload and short circuit to ground or to the supply voltage, overtemperature, and undervoltage supply     

Design of LIGBT protection circuit for smart power integration

Development of a monolithic power integrated circuit by making the lateral insulated gate bipolar transistor (IGBT) the main switching device is a current topic. The overcurrent protection scheme is usually necessary to be built as part of the function in such a power integrated circuit. The protection circuit requires distinguishing various fault conditions and reacting differently based on the device safe operating area (SOA) limitation. At the same time, the protection circuit should also be relatively concise and suitable for integration. In this paper, a concise circuit suitable for integration and with gate drive capability is proposed to provide the complete function of overcurrent SOA protection for the LIGBT. The operational principle was described in detail and the circuit performance was verified with experimental results from both the discrete circuit and the fabricated LIGBT integrated circuit     

新型煤矿供电网防越级跳闸保护装置的研制

以煤矿供电网越级跳闸现象为研究对象,在分析电流纵联差动保护、级联闭锁工作原理和防越级跳闸保护逻辑的基础上,介绍了一种煤矿供电网防越级跳闸保护装置的研制过程。保护装置以32位ARM处理器MB9BF618S为控制核心,可以实时检测供电网输电线路的工作状态,对输电线路故障进行有效的保护。文中主要叙述了保护装置的总体结构,给出了电流/电压输入模块、开关量输入/输出模块和通信模块的设计方案。该保护装置具有结构简单、操作方便、可靠性高等特点,能够满足煤矿供电网防越级跳闸保护的要求,具有较高的应用价值。     

霍尔传感器在大功率晶闸管保护电路中的应用

详细介绍了霍尔传感器在大功率晶闸管保护电路中的特殊应用,特别是在大功率晶闸管过载保护中解决了快速熔断器一次性保护的缺点。霍尔传感器在短路状态下对大功率晶闸管能够快速保护,是当前大功率晶闸 管保护电路中较先进的保护电路,也是非破坏性保护电路。     

优化理论与最优控制在断路器操作回路中的应用

优化理论与最优控制理论是现代控制理论理论的核心,它是通过一些控制手段和约束条件,在特定条件下将控制效果达到最佳.坚强智能的电力系统的离不开继电保护,继电保护装置就是能反映电力系统中各电气设备发生故障或不正常工作状态,并作用于断路器跳闸或发出信号的一种自动装置.本文从优化理论和最优控制的角度,对继电保护作用于电路器的控制的最优化展开介绍,使得断路器安全可靠的运行,保证电力系统的稳定性.     

Mitigation and analysis of arc faults in automotive DC networks

The introduction of system voltages higher than 24 VDC in vehicles, forces considerable component and system changes regarding reliability and electrical safety. In the instance of an arc fault, e.g., when a wire is cut, pinched, chafed or breaks under load, or an arc is drawn between disconnecting terminals, the resulting fault current may be significantly lower than the trip current of common protection devices such as fuses or circuit breakers. In these cases, the fault is cleared late (depending on the time/current characteristics) or, in some cases, not at all. The authors discuss different types of arc faults and introduce approaches to deal with them.     

基于Cotex-M3内核的智能低压断路器控制器设计

文章介绍了基于Cotex-M3内核的32位高性能微控制器在智能低压断路器控制器的硬件及软件设计中的应用。本智能控制器硬件采用信号变换、波形变换法;软件采用微分法。具体是通过微控制器中集成的PWM输入捕获模式采样变换后的信号来间接计算电流的变化率,大大缩短了过载、短路故障电流的响应时间。智能低压断路器控制器,除实现故障保护功能外,还能对环网供配电系统的现场参数进行实时性监测、区域联网通信等,真正能实现"分布式控制、集中管理",降低现场维护的难度,提高了整个区域环网供配电系统的安全性和可靠性。     

Fault Current Limiter Based on Resonant Circuit Controlled by Power Semiconductor Devices

This work presents a resonant fault current limiter (FCL) controlled by power semiconductor devices. Initially the operation of two ideal resonant circuit topologies as fault current limiter are discussed. The analysis of these circuits is used to derive an alternative topology to the fault current limiter based on the connection of a series and a parallel resonant circuit. Digital models are implemented in the SimPowerSystem/Matlab simulation package to investigate the performance of the proposed FCL to protect transmission and distribution electric networks against short circuit currents. Transfer functions of the linear limiter models are used to identify the effect of each element of the FCL over its stability and its transient response. The developed analysis will be used to derive modifications in the FCL topology in such a way to improve their dynamic response.     

基于MATLAB的高压供电系统故障分析

随着电力系统规模的越来越大和复杂程度的越来越高,传统的人工建模已不能满足电力科研实验的要求,为了适应电力系统的发展,采用了基于MATLAB的仿真方法。在分析供电系统变压器低压侧母线短路电流和冲击电流的基础上,利用MATLAB的电力系统工具箱建立短路仿真模型,运行仿真,得出了故障时电压电流波形,分析了其故障特征,得到理想的仿真结果。因此,在电力系统设计和运行中,可以运用MATLAB对电路进行短路计算和仿真,对供电系统的故障分析、继电保护整定具有指导意义。     

Modern IGBT gate driving methods for enhancing reliability of high-power converters — An overview

This paper presents a survey of existing gate driving approaches for improving reliability of Insulated Gate Bipolar Transistors (IGBTs). An extensive and various lists of techniques are introduced and discussed, including fast detection, identification and protection against IGBT failures, also considering cost-effective solutions. Gate-driver circuit solutions to improve short-circuit robustness, overload, voltage and current overshoots withstanding capability are first introduced to cope with abnormal conditions severely affecting lifetime expectation. Later, some advanced, state-of-the-art control techniques are discussed to minimize the real-mission-profile stresses in terms of voltage and current stresses to the device, together with, not least, temperature variations. Future challenges and perspectives are finally discussed at the end of the paper.     

基于配电自动化多层数据应用的配网多条线路同时跳闸故障分析

珠海某区域配电网线路发生故障后引起其他线路同时动作,故障分析难度较大.针对此类较为复杂的连锁故障情况,本文提出了基于配电自动化多层数据的故障分析查找方法,并针对一例该区域配电网连锁故障跳闸情况进行了分析,根据分析结果查找故障点,有效地定位了故障设备,并对单条线路发生故障时造成同段母线上其它线路同时连锁跳闸的现象进行了分析解释.针对此类配电网故障,珠海供电局研发了配网线路一体化故障控制终端设备,该设备可对配网线路故障情况下的电压、电流量进行录波,有效判断故障类型、地点以及保护动作是否为误动,为故障查找定位提供参考.     

Latchup-free ESD protection design with complementary substrate-triggered SCR devices

The turn-on mechanism of silicon-controlled rectifier (SCR) devices is essentially a current triggering event. While a current is applied to the base or substrate of an SCR device, it can be quickly triggered on into its latching state. In this paper, latchup-free electrostatic discharge (ESD) protection circuits, which are combined with the substrate-triggered technique and an SCR device, are proposed. A complementary circuit style with the substrate-triggered SCR device is designed to discharge both the pad-to-V/sub SS/ and pad-to-V/sub DD/ ESD stresses. The novel complementary substrate-triggered SCR devices have the advantages of controllable switching voltage, adjustable holding voltage, faster turn-on speed, and compatible to general CMOS process without extra process modification such as the silicide-blocking mask and ESD implantation. The total holding voltage of the substrate-triggered SCR device can be linearly increased by adding the stacked diode string to avoid the transient-induced latchup issue in the ESD protection circuits. The on-chip ESD protection circuits designed with the proposed complementary substrate-triggered SCR devices and stacked diode string for the input/output pad and power pad have been successfully verified in a 0.25-/spl mu/m salicided CMOS process with the human body model (machine model) ESD level of /spl sim/7.25 kV (500 V) in a small layout area.     

Integrated overcurrent protection system for class-D audio power amplifiers

A fully integrated overcurrent protection system is presented suitable for application in integrated class-D audio power amplifiers. Accurate overcurrent detection is used based on parallel measurement of the voltage drop across the DMOS power transistors. A logic circuit enables continuous current limiting during overload situations. Actual short circuits can be distinguished from load impedance minima using a simple short-circuit discrimination method.     

配网中自适应电流速断保护的应用

在阐述传统电流速断保护和自适应电流速断保护构成原理及特点的基础上,对自适应式电流速断保护在单端电源条件下发生在正、反方向故障时的动作性能进行了分析。结果表明,自适应电流速断保护性能比传统电流保护具有明显的优越性及适用条件。