Firstly , after analyzing the generated mechanism of surplus power , it can be found that surplus power affects the capability of loading seriously . secondly , according to the classical control theory , analyzes the capability of system and adopts pid and interfere compensation to eliminate the effects of the surplus power 本论文首先分析了加载系统的加载原理,和多余力的产生机理和本质特性,得出多余力严重影响加载系统的加载性能,并且这种多余力是由于承载对象的位置变化引起的。
Besides , the converters have unmodeled dynamics . so the traditional controller for hvdc based on the classical control theory can not meet the requirements in practice . although , pi controllers are widely used in the hvdc systems , they have high sensitive responses to random disturbances , low robust performance , and can not solve some problems in power systems , such as unmodeled dynamics , nonlinear uncertainties 直流输电线路中的换流器具有很强的非线性,系统的运行工况随时都会发生改变,系统扰动发生的地点、类型及严重程度具有随机性;此外,换流器还含有未建模动态部分,这些因素使得基于直流输电系统准静态模型的常规控制器设计方法常常不能很好地满足系统的实际要求。