柔性直流系统的交流侧故障穿越优化控制策略

AC-side Fault Crossing Optimization Control Strategy for VSC-HVDC

基于模块化多电平换流器(Modular multilevel converter,MMC)的柔性直流输电在大规模的风电并网中具有广阔的发展前景,针对风电接入下交流侧故障时MMC的故障穿越能力进行研究,提出一种基于功率预测控制的交流侧故障穿越控制方法,通过新型瞬时功率理论建立功率预测控制模型及环流预测控制模型,并以上下桥臂插入子模块数为控制变量,相比于传统的功率控制理论,无需计算功率补偿项,能够实现有功及无功功率的同步控制,采用的分层预测控制模型,无需引入权重因子,控制系统结构简单、计算量小,最后通过Matlab/Simulink仿真平台建立仿真模型,仿真结果表明所提控制策略能够实现稳态及网压不平衡故障情况下的有效控制。

Flexible HVDC transmission based on modular multi-level converter(MMC)has broad prospects for development in large-scale wind power grid-connected.The fault-crossing capability of MMC in AC side fault under wind power access is studied,a fault-crossing control method for AC side based on predictive direct power control is proposed.A predictive power model and a circulating current predictive control model are established through a new instantaneous power theory.Compared with the traditional power control theory,the insertion of sub-modules into the lower arm is a control variable,which can realize the synchronous control of reactive power and active power without calculating the power compensation term.The hierarchical predictive control model is adopted without introducing the weight factor.The control structure is simple and accurate.Finally,the simulation model is established through the simulation platform of Matlab/Simulink.The simulation results show that the proposed model can achieve the synchronous control of reactive power and active power without calculating the power compensation term.The control strategy can achieve effective control in the case of steady state and unbalanced network voltage.