一种新型电能转换技术及其应用

A New Technology and Application of Electric Power Transform

某火电厂原有集中式变频供电系统为一批大型辅机提供集中调速电源。由于该供电系统为独立微电网,为维持系统频率稳定性及满足辅机变频运行需要,汽轮机的调节阀门长期处于节流状态,尤其是中低负荷区间时辅机变频运行所需功率相对汽轮机下降得更快,加剧了节流损失。本文介绍的新型电能转换技术属跨界集成创新,基于现有电力电子变频技术和产品,在现有集中变频供电系统与工频系统之间,研发并增设一套新型电能转换系统,实现了集中式变频供电系统与厂用电工频系统两个异频电网之间的联络运行,将集中变频供电系统变化的电压、频率经转换后,输出为可运行于现有工频系统的交流电源,并将集中变频供电系统的富裕功率送至现有工频系统。通过调节新型电能转换系统的输出功率,基本代替汽轮机调节阀门的调速功能,而且使汽轮机调门接近全开,减小节流损失、提高机组性能。

A centralized variable frequency power system has been built in a power plant to supply common electric power of speed governing operation for a number of large motors.However,the system forms a microgrid which frequency is different from utility power grid,so the turbine regulating valves often operate in throttling state,which not only provide the speed required by motors,but also keep the turbine speed stable.This means a lot of throttling loss,especially when the lower speed need of motors.The paper introduces a new technology of electric power transform based on the existing IGBT technology and product,which a new electric power transform system is developed and applied.The new system is an integrated innovation,successfully interconnects centralized variable frequency power system with utility power grid,converts varying voltage and frequency to nominal voltage and frequency,and transfer spare energy due to turbine valves almost fully open from centralized variable frequency power system to utility power grid.In addition to greatly reducing throttling loss,by adjusting the output power of the new system instead of turbine valves,like a backward acting regulating valve of electric,the system speed can be controlled well.The new system improves the performance of power plant unit.