一种适用于变频器低电压穿越电源的三重Boost电路仿真及实验分析

电厂及各类工矿企业的辅机大量采用变频器,而此类变频器抵抗电压跌落能力差、不具备低电压穿越能力,易造成的机组停机故障,直接威胁电网安全。因此研制变频器低电压穿越电源(LVRT),在电网故障时支撑变频器运行,具有重要意义。针对该问题,采用经典的DC-DC升压电路,研制出了基于三相交错并联Boost直流变换电路的LVRT电源,仿真及现场实验均显示,三相Boost交错并联可以减小输入电流纹波和开关管应力,且三相电流具有很好的一致性,能有效的提高变频器的低电压穿越能力且具有良好的动静态输出特性。     

一种新型的单相并网系统锁相环

电网电压的相角、频率对并网逆变器而言是最基本的信息.准确快速地跟踪电网电压是并网控制系统稳定运行的保障.在单相并网逆变器中,常规的过零点检测锁相方法往往对电网电压畸变或扰动敏感,使得锁相环处于不稳定状态,从而导致并网逆变系统性能降低,甚至不能正常工作.针对此问题,分析了基于同步旋转坐标变换的锁相环原理,并将这种锁相策略...     

交流励磁变频器动模系统主回路设计

针对国内目前没有交流励磁的运行案例,交流励磁的控制技术的研究就显得尤为必要和紧迫。设计了一套交流励磁三电平变频器动模系统,针对影响系统运行性能的LCL滤波器和直流平波电容进行了深入的设计分析,给出动模设计方法,并对所设计的滤波器和电容进行了仿真和动模验证。验证结果显示,该设计方法是可行的。     

Hybrid beamforming with discrete phase shifters for millimeter wave backhaul networks

Hybrid beamforming (HBF) technology becomes one of the key technologies in the millimeter wave (mmWave) mobile backhaul systems, for its lower complexity and low power consumption compared to full digital beamforming (DBF). Two structures of HBF exist in the mmWave mobile backhaul system, namely, the fully connected structures (FCS) and partially connected structures (PCS). However, the existing methods cannot be applied to both structures. Moreover, the ideal phase shifter is considered in some current HBF methods, which is not realistic. In this paper, a HBF algorithm for both structures based on the discrete phase shifters is proposed in the mmWave mobile backhaul systems. By using the principle of alternating minimization, the optimization problem of HBF is decomposed into a DBF optimization problem and an analog beamforming (ABF) optimization problem. Then the least square (LS) method is enabled to solve the optimization model of DBF. In addition, the achievable data rate for both structures with closed-form expression which can be used to convert the optimization model into a single-stream beamforming optimization model with per antenna power constraint is derived. Therefore, the ABF is easily solved. Simulation results show that the performance of the proposed HBF method can approach the full DBF by using a lower resolution phase shifter.     

配网串补装置关键技术研究与应用

为了解决我国偏远地区配电网长期存在的无功功率不足和电压质量不合格的问题,研制了一种适用于10 kV配电网的串联电容器补偿装置。电容器组是该配网串补装置的核心设备,晶闸管开关与旁路接触器结合组成了配网串补的过电压保护设备,操作断路器和隔离开关可以实现配网串补系统的投入和退出。该配网串补装置配置有电压、电流互感器,用于测量进线线路电压、线路电流、电容器电压。装置通过无线通信模块与配网主站构成局域网,可以实时上送运行信息,方便主站监控。并对该装置的过电压保护方式、电容器阻抗保护等关键技术作了详细阐述。研制的配网串补装置已在江苏电网成功投运,试验和运行结果证明:本装置能很好地补偿线路低电压,优化功率因数,具有良好的经济效益和社会效益。