多端口电力电子变压器的安全稳定运行区域分析与控制

Analysis and Control of Safe and Stable Operation Region for Multi-port Power Electronic Transformer

多端口电力电子变压器(PET)是交直流混合配电网组网的关键设备。然而,当多端口负荷功率差异较大时,将引起PET相间或相内功率严重不平衡从而超出PET的功率传输能力,导致系统不稳定。因此,提出一种级联式跨相并联型多端口PET的安全稳定运行区域分析方法及其稳定控制策略。首先,建立基于调制比的系统稳定运行约束条件;然后,推导系统安全稳定运行区域及边界的解析表达式,给出其安全稳定运行裕度的定义和计算方法;最后,提出提升PET安全稳定运行裕度的功率转移策略,利用MATLAB/Simulink仿真验证了所提策略的有效性。

Multi-port power electronic transformer(PET)is the key equipment for AC/DC hybrid distribution network.However,when the difference in multi-port load power is large,it will cause a serious imbalance of PET interphase or in-phase power,which will exceed the power transmission capacity of PET and lead to system instability.Therefore,a safe and stable operation region analysis method and a stability control strategy of cascaded inter-phase parallel connected multi-port PET(CIPCM PET)are proposed.Firstly,the stable operation constraints of the system based on modulation ratio are established.Then,the analytical expressions of the safe and stable operation region of the system and its boundary are derived,and the definition and calculation method of the safe and stable operation margin are given.Finally,a power transfer strategy is proposed to improve the safe and stable operation margin of the PET.The effectiveness of the proposed strategy is verified in MATLAB/Simulink simulation.