油气处理厂埋地管道PCM检测的电流控制方法

针对使用PCM(多频管中电流法)对油气处理厂的埋地管道进行检测时,输入电流在三通处会受管道支管的影响而产生分流的问题,将检测的管道分支看成是并联电路,在输入电压不变的情况下,通过降低检测目标管段回路电阻的方法,控制埋地管道各支路PCM检测的输出电流信号强度,使检测电流信号更多地向待检测的管段分配,完成对油气处理厂埋地管道的定位。

宽带差动跨阻抗DAC输出接口设计要领

高速数字模拟转换器（DAC）通常会提供一组互补的电流输出信号。多数的输出接口建置会使用一组电阻负载和／或变压器来将这组电流源信号转换为电压。当需要直流耦合（dc-coupled）接口时．设计精细的差动转阻级（differential transimpedance stage）就成了极佳的替代选择。这篇文章将说明先使用宽带双路运算放大器（wideband dual op amp）．再使用新式全差动放大器（fully-differential amplifier．FDA）的设计考虑与选项。同时也说明范例电路和仿真表现。

Adaptive controller design based on input-output signal selection for voltage source converter high voltage direct current systems to improve power system stability

An input-output signal selection based on Phillips-Heffron model of a parallel high voltage alternative current/high voltage direct current(HVAC/HVDC) power system is presented to study power system stability. It is well known that appropriate coupling of inputs-outputs signals in the multivariable HVDC-HVAC system can improve the performance of designed supplemetary controller. In this work, different analysis techniques are used to measure controllability and observability of electromechanical oscillation mode. Also inputs–outputs interactions are considered and suggestions are drawn to select the best signal pair through the system inputs-outputs. In addition, a supplementary online adaptive controller for nonlinear HVDC to damp low frequency oscillations in a weakly connected system is proposed. The results obtained using MATLAB software show that the best output-input for damping controller design is rotor speed deviation as out put and phase angle of rectifier as in put. Also response of system equipped with adaptive damping controller based on HVDC system has appropriate performance when it is faced with faults and disturbance.