摘要
低载波比(载波频率与基波频率之比)的载波移相调制策略可有效降低MMC-UPFC的开关损耗,但会导致“减频效应”造成电容电压谐波频率明显降低,严重削弱电容电压均衡策略的控制效果。根据电容电压谐波频率随载波比降低的规律,定量分析了低载波比调制下MMC-UPFC电容电压的减频效应,明确了低载波比与电容电压低频波动、子模块电容不稳定充放电状态和子模块间电容电压不均衡间的内在联系及其发生机理;在此基础上,提出一种基于RBF神经网络的减频效应抑制策略,通过检测电容电压的谐波分量进行最优载波比选择和电容电压控制。最后以苏州南部500kV UPFC示范工程为参考进行仿真,证明了MMC-UPFC电容电压的减频效应的存在性以及抑制方法的有效性。
The carrier phase-shifting modulation strategy with a low carrier ratio(the ratio of carrier frequency to fundamental frequency)can effectively reduce the switching loss of MMC-UPFC but is prone to lead to a"frequencydecrease effect",resulting in a significant reduction in the harmonic frequency of the capacitor voltage,which severely weakens the control effectiveness of the capacitor voltage balancing strategy.Based on the rule that the harmonic frequency of the capacitor voltage decreases with the carrier ratio,this paper quantitatively analyzes the frequency reduction effect of MMC-UPFC capacitor voltage under low carrier ratio modulation.It clarifies the intrinsic relationship and occurrence mechanism between the low carrier ratio,low-frequency fluctuation of capacitor voltage,unstable charging and discharging state of sub-module capacitors,and imbalance of capacitor voltage among sub-modules.On this basis,a frequency reduction effect suppression strategy based on RBF neural networks is proposed,which optimizes carrier ratio selection and capacitor voltage control by detecting the harmonic components of the capacitor voltage.Finally,simulations were conducted using the 500kV UPFC demonstration project in southern Suzhou as a reference,demonstrating the existence of the frequency reduction effect of MMC-UPFC capacitor voltage and the effectiveness of the suppression method.
作者
陈志军
王骏
郁超
张珂
赵云龙
王楚扬
CHEN Zhijun;WANG Jun;YU Chao;ZHANG Ke;ZHAO Yunlong;WANG Chuyang(Suzhou Power Supply Company of State Grid Jiangsu Electric Power Company,Suzhuo 215000,Jiangsu,China;School of Energy and Electrical Engineering,Hohai University,Hohai University,Nanjing 211106,Jiangsu,China)
出处
《电网与清洁能源》
CSCD
北大核心
2024年第10期93-104,共12页
Power System and Clean Energy
基金
江苏省电力有限公司科技项目“基于设备画像的区域电网柔性电力电子设备性能提升技术研究”(J2023001)。
关键词
模块化多电平换流器
统一潮流控制器
减频效应
载波移相调制
RBF神经网络
modular multilevel converter
unified power flow controller
frequency-decrease effect
carrier phase-shift PWM
RBF neural network
