The Modular Multilevel Matrix Converter can realize the three-phase AC-AC transformation. Its outstanding advantages are easy to modularize, high reliability and low harmonic content, which can be used in high-voltage and large-capacity driven system. Aiming at the shortcomings of traditional PI control, such as slow stability, easy overshoot and poor dynamic performance, this paper proposes a new nonlinear Flatness-Based-Control strategy based on Differential Flatness theory, which has the advantages of fast response, no overshoot, no static error in tracking and high dynamic performance. It can greatly improve the control effect of M3C input-side and output-side current. And under the operating conditions of input-side frequency changes, the Flatness-Based-Control strategy can still maintain the extremely low impact of the system, and the overall control effect is better. At last, the correctness and superiority of this method are verified by experiments under different working conditions.

电力电子变压器(PET)具有瞬时功率调节、谐波抑制等优点,输电线路经过PET向无源网络供电是柔性输电的一个重要应用领域.将模块化多电平变换器(MMC)技术与PET相结合,使得PET应用于高电压、大容量的输电和配电系统成为了可能.首先,本文针对MMC-PET输入级在电网故障时产生的正负序电流,推导出基于欧拉-拉格朗日(EL)模型的内环正负序电流的无源控制器(PBC);接着,将MMC技术应用于MMC-PET中间隔离级高压侧,提高其中间隔离级的供电可靠性,并采用移相调压的控制策略;再后,针对MMC-PET输出级,设计了基于EL模型的内环电流无源控制器.最后,在Matlab/Simulink中建立一个向无源网络供电的MMC-PET系统,在电网电压出现故障时,对向无源网络供电的MMC-PET系统进行了软件仿真实验验证,实验结果表明MMC-PET系统的控制策略具有良好的动态控制性能.

MMC-DVR combined with dynamic voltage regulator（DVR）and modular multilevel converter（MMC）can be used to solve the problem of sag/swell compensation for medium and high voltages. Since MMC-DVR is a non-linear system，the compensation effect of linear control methods such as PID commonly used in DVR systems is not satisfactory. To this end，this paper proposes a passive nonlinear control method for the MMC-DVR system，which can be deeply integrated in the wind farm grid-connected system，and can solve the negative problems such as power quality degradation. First，the circuit topology and working principle of MMC-DVR are introduced，and the mathematical model under the static and rotating coordinate system is established. Then，the passive control method is proposed to solve the problem. Finally，the MMC-DVR control system is built on Matlab/Simulink software experimental platform， and the experimental results verify the feasibility and superiority of the passive nonlinear control strategy proposed in this paper .

This paper reports finite state based model predictive control method for unified power quality conditioner based on modular multilevel converter. This control reverses and optimizes bridge arm sub-modules conducting number through the output as well as change trend, which can narrow control set to greatly and reduce the computation. Since unified power quality conditioner based on modular multilevel converter needs to control both voltage and current quality, multi-step control is adopted in proposed control at the same time to achieve better control effect. After analysis and calculation, finite state based model predictive control method proposed has a small amount of calculation and excellent dynamic and static characteristics compared with other predictive control. Voltage and current can be restored by this control method in the case of voltage imbalance, transient, harmonic wave, etc.

模块化多电平矩阵变换器(modular multilevel matrix converter,MMMC)具备模块化的优点,能实现三相AC-AC的变换,且可用于高电压大功率的场合.但传统的载波移相调制策略在MMMC的模块数为偶数时,会导致桥臂上两两H桥子模块的输出电压发生100％的重合,从而致使桥臂上H桥子模块不能被高效使用.另一方面,桥臂上H桥子模块总输出电平数也会因此锐减,使得MMMC的工作效率低下.为了解决上述问题,提出一种新型的调制策略(即双载波调制策略)能够解决此问题且能大大提高MMMC 的输出效果.通过理论分析、推导和在MATLAB/Simulink仿真平台上进行两种调制策略的仿真对比,验证了在MMMC的模块数为偶数时,在同等条件下,采用新型调制策略的输出效果优于采用传统调制策略的输出效果,且新型调制策略仅需传统调制策略一半的模块数就能达到与传统的调制策略一样的效果.因此新型的调制策略具有更高的经济性和应用价值.

基于模块化多电平变换器(modular multilevel converter,MMC)的统一电能质量调节器(unified power quality conditioner,UPQC)可用于高电压下电压电流的电能质量综合治理,但当电网电压不平衡时,电流电压相位和幅值发生变化,给综合治理带来困难.将无源控制方法应用到MMC-UPQC中,以解决电网电压不平衡下的电能质量问题.首先,根据MMC-UPQC的拓扑结构,建立其在不平衡电网下的数学模型;然后,根据正负序分离方法,对检测量进行无需锁相环的分离;接着基于无源控制理论,搭建基于E-L模型的无源控制器,并将其应用到多电平、高电压的电能质量补偿系统中;最后,利用串联侧补偿电压和并联侧补偿电流的原理,通过协调控制综合解决不平衡状态下的电网电能质量问题.Matlab/Simulink平台实验结果发现基于所提无源控制器的MMC-UPQC系统响应时间小于0.05 s且总谐波失真度小于5％,验证了其解决电能质量综合治理问题的有效性和优越性.

模块化多电平矩阵变换器(M3C)在风力发电中具有突出优势,可实现从低频交流电到工频交流电的AC/AC变换.为了解决比例-积分(PI)控制调节参数多、谐波含量高等问题,文中依据无源控制理论,分析了M3C输入侧数学模型的无源性及稳定性,提出其无源控制策略.通过MATLAB/Simulink建模仿真,验证了所提无源控制策略的正确性和优越性,并且模拟了输入侧频率变化、输出侧负载变化时,通过无源控制策略实现M3C的变频及变负载运行.相比于PI控制,所提无源控制响应更快、调节参数更少、谐波含量更低,整体控制效果更好.

电网电压不平衡时,电流电压波动较大,基于模块化多电平变换器(MMC)的统一电能质量调节器(UPQC)采用简单的PI控制难以调节电能质量.针对MMC-UPQC在电网电压不平衡的运行状态,提出一种基于正负序分离MMC-UPQC的微分平坦控制(DFBC)方法,它能够综合治理电压和电流的电能质量问题.首先,根据MMC-UPQC的拓扑结构,建立其在不平衡电网下的数学模型,分析MMC-UPQC的内部特性,验证MMC-UPQC的平坦性和稳定性;然后,根据正负序分离方法,采用无需锁相环方法对检测量进行分离,基于微分平坦控制理论,搭建结合前馈参考轨迹和误差反馈补偿的微分平坦控制器,并将其应用到多电平、高电压的MMC-UPQC电能质量补偿系统中,综合解决电网电压不平衡状态下的电网电能质量问题;最后,通过实验验证了基于所提微分平坦控制器的MMC-UPQC系统解决电压暂升、暂降和注入谐波问题的有效性和优越性.

该文将无源控制(PBC)引入到一种准Z源三电平并网逆变器上,该方法无需对逆变器系统进行线性化处理,就可实现良好的并网控制.首先,讨论逆变器拓扑的工作原理,推导出逆变器整体数学模型,给出无源E-L(Euler-Lagrange)方程形式;然后,验证逆变器系统具有严格的无源特性,通过采用合适的阻尼注入和控制率,加速逆变器系统达到期望点,得到逆变器并网电流解耦的无源控制规律,设计出逆变器的无源控制系统,并结合正弦脉宽调制(SPWM)算法驱动逆变器的开关动作;最后,在Matlab/Simulink软件仿真平台和硬件平台上进行实验,实验结果表明,该文基于E-L模型的无源控制策略具有动态特性好、鲁棒性强等优点.

模块化多电平变流器(MMC)逐渐被应用于并联型有源滤波器(SAPF).针对电力系统的非理想运行状态,提出了一种基于Lyapunov函数的正负序分离的控制策略,该控制策略可根据SAPF的容量灵活地选择补偿信号.首先根据MMC型SAPF(MMC-SAPF)的数学模型,建立经正负序分离后MMC-SAPF的Lyapunov函数控制器模型,选择最优控制增益;其次加入适用于电网非理想条件下的准比例谐振环流控制、电容电压控制器以提高系统性能;最后基于MATLAB/Simulink软件仿真平台和硬件实验平台,分别在理想、非理想条件下验证了所提Lyapunov函数控制策略对MMC-SAPF的有效性和优越性.仿真和实验结果表明所提Lyapunov函数控制策略能够快速、准确地补偿电流谐波,具有调节参数少、鲁棒性强、控制精度高等优点.