摘要
模块化多电平换流器(MMC)在高压大功率能量变换领域应用广泛,尤其在高压直流输电系统中,当桥臂子模块达上百个时,需要配置上百个电压传感器实时测量子模块电容电压,并根据调制策略分配各子模块的开关控制信号,大量传感器的使用增加了测量系统的复杂度和生产成本。针对MMC系统传感器数量较多的问题,在采用最近电平调制的基础上,提出一种单传感器电容电压平衡控制策略。区别于传统测量方法为每个子模块配置一个电压传感器,该策略采用每个桥臂只配置一个电压传感器,用于测量桥臂电压,并结合桥臂电流的充放电方向对各子模块电容电压进行实时预测校正,实现电容电压的平衡;同时,进一步定性分析系统调制度和控制频率对预测校正平衡控制策略的影响,为选取合适的控制参数提供依据。仿真和实验结果验证了所提方法在稳态和暂态工况下的正确性和稳定性。
Modular multilevel converter(MMC)is widely used in the field of high power and high voltage energy conversion.Especially in high voltage direct current(HVDC)transmission system,there are hundreds of submodules(SMs)in each arm,and a large number of sensors need to be installed to measure the capacitor voltages of all SMs.Then the switching signals are allocated for SMs by means of modulation strategy.The use of a large number of sensors increases the complexity and costs of the measurement system.Therefore,in this paper,a balance control strategy with single sensor measurement based nearest level modulation(NLM)for capacitor voltages is proposed.Different from the conventional measurement with individual voltage sensor for each SM,the proposed strategy employs only one voltage sensor for each arm to measure arm voltage.Combining the measured arm voltage and the charging/discharging direction of the arm current,the capacitor voltage can be obtained through prediction-modification operation in real time to realize the capacitor voltages balance control.Simultaneously,the influence of modulation ratio and control frequency on the prediction-modification balance control strategy can be further qualitatively analyzed,which can provide evidence for selecting proper control parameters.Simulation and experimental results validate the correctness and stability of the proposed strategy under transient and steady-state conditions.
作者
岳雨霏
徐千鸣
罗安
郭鹏
Yue Yufei;Xu Qianming;Luo An;Guo Peng(National Electric Power Conversion and Control Engineering Technology Research Center Hunan University Changsha 410082 China)
出处
《电工技术学报》
EI
CSCD
北大核心
2018年第16期3663-3676,共14页
Transactions of China Electrotechnical Society
基金
国家重点研发计划(2017YFB0902000)
国家自然科学基金面上项目(51477045)
博士后创新人才支持计划(BX201700311)资助
关键词
模块化多电平换流器
最近电平调制策略
单传感器测量
预测校正
平衡控制策略
Modular multilevel converter(MMC)
nearest level modulation(NLM)strategy
single sensor measurement
prediction-modification
balancing control strategy
