亭子口电站机组同期装置的优化改造

亭子口电站1-4号机组监控系统原同期回路分为手准和自准回路（同期合闸和双侧无压合闸）,合闸出口回路串联一个同步检查闭锁继电器.自投产以来,先后多次发生由于同步检查闭锁继电器接点动作不可靠造成同期并网不成功;且同期装置存在硬件故障缺陷,使装置内部接点误开出;监控系统PLC的复归“投PT信号”指令、复归“启动同期”指令流程不合理;在机组同期并网过程中,调速器系统不接受同期装置下发的增速或减速等调频指令,造成同期装置采集到的频差信号不满足合闸条件,导致机组并网过程很慢或并网超时流程退出等现象;针对以上存在的问题对其同期装置硬件和软件进行优化改造、对调速器并网控制逻辑进行优化,使问题得以彻底解决.

台电五期汽轮机ETS保护系统改进与优化

台电五期机组的ETS系统投产以来,因设计及设备等原因出现了一些不安全现象,严重影响机组安全生产稳定。为此,热工人员对五期机组的ETS系统进行了全面的分析整理,根据五期机组特点并借鉴其他机组成功经验,系统性的对两台机组的ETS系统进行了改进优化,提高设备可靠性和机组的安全性。

Modular Multilevel Inverter with Maximum Power Point Tracking for Grid Connected Photovoltaic Application

A single-phase modular multilevel inverter based photovoltaic system for grid connection is proposed. This photovoltaic system utilizes two conversion stages： a boost converter for tracking the maximum power point and a modular multilevel inverter used as an interfacing unit. The maximum power point tracking is achieved with a fuzzy logic controller, and the modular multilevel inverter regulates the DC link voltage and synchronizes the grid voltage and current in order to achieve unity power factor operation. The proposed system provides high dynamic performance and power quality injected into the grid. The validity of the proposed system is confirmed by simulations.