MMC柔性直流输电系统功率骤变附加控制

Additional Power Change Control for Modular Multilevel Converter Based on Flexible HVDC Systems

为了提高柔性直流输电系统紧急功率调节时换流站母线电压的稳定性,引入了dq0坐标系下系统功率控制数学模型.通过对模块化多电平换流器(Modular Multilevel Converter,MMC)功率控制方式深入研究,发现了柔性直流输电系统的有功功率和直流电压的平方成比例微分关系,从而提出了功率骤变附加控制环节.当交流电网出现功率波动时,加入附加控制环节后,交直流系统的穿越功率更加快速平稳地恢复到给定值.最后基于搭建的51电平MMC交直流混合系统仿真模型,利用数值仿真方法分析了功率翻转情况的系统特性,结果表明MMC系统在加入功率骤变附加控制环节后,系统的有功功率和直流电压响应特性更好,验证了功率骤变附加控制的有效性.

In order to improve the stability of flexible HVDC systems converter bus voltage, while adjusting the emergency power, the mathematical model of power control in dq0 coordinate system is introduced. Based on the learn of the power control mode of the modular multilevel converter, it is found that the active power of the system is proportional differential to the square of the DC voltage, and then an additional power change control loop is proposed. When the power fluctuation occurs in the AC power grid, the additional control to make the cross power of the AC and DC power system more quickly and smoothly return to a given value. Finally, based on the 51 level MMC AC/DC hybrid system simulation model,the system characteristics of power flip are ana- lyzed by the numerical simulation method. The simulation results show that the MMC after adding additional control aspects of the sudden change of power, the active power and DC voltage response characteristics better, which verified the effectiveness of the additional control of the power system.