摘要
针对基于两电平电压源换流器(voltage source converter,VSC)的HVDC系统,为实现两电平VSC在获得较优谐波特性的同时,尽可能降低开关频率、提高暂态控制能力,文中提出一种将特定次谐波消除脉宽调制(selective harmonic elimination pulse width modulation,SHEPWM)与3次谐波注入SPWM相结合的混合脉宽调制技术。运用"幂和理论",提出一种两电平SHEPWM非线性超越方程组求解算法,可显著降低运算量。通过构建稳态控制单元、状态监测器、暂态控制单元与选择器,较好地实现了混合调制的目标。并通过仿真加以验证,结果表明,此混合脉宽调制技术可提高VSC-HVDC工程的效率、可靠性及经济性。
For HVDC transmission system based on two-level voltage source converter （VSC）, in order to decrease switching frequency and improve transient control ability as possible while the two-level VSC attains better harmonic characteristic, in this paper a hybrid PWM technology that combines selective harmonic elimination pulse width modulation （SHEPWM） with third harmonic injected SPWM is proposed. By use of power sums theory, an algorithm to solve two-level SHEPWM nonlinear transcendental equations is put forward which can reduce computational burden greatly. By means of constructing steady-state control unit, state detector, transient control unit and selector, the objective of hybrid modulation is implemented well and validated by simulation. Simulation results show that such a hybrid PWM technology can improve efficiency, reliability and economy of VSC-HVDC.
出处
《电网技术》
EI
CSCD
北大核心
2009年第7期7-13,共7页
Power System Technology
基金
国家重点基础研究发展计划项目(973项目)(2004CB217907)
国家电网公司重点科技项目SGKJ[2007]249)~~
