摘要
当多端高压直流输电系统用于远距离输电时,直流线路的电压降落以及线路功率损耗会对电压裕度控制的精度带来较大影响,使直流电压不能稳定控制于一点,为此提出一种适用于多端柔性直流输电系统的精确电压裕度控制方法。推导了多端柔性直流输电系统的dq坐标数学模型,基于直流系统潮流计算的思想,充分考虑线路压降和损耗对控制参考值的影响,对电压裕度的取值进行计算,并在控制器中实现裕度修正。在PSCAD/EMTDC环境中建立了基于模块化多电平换流器的三端直流系统仿真模型,仿真结果验证了所提出的控制方法的正确性和有效性,该方法能够有效避免因电压裕度取值不当造成的控制特性偏移,并在系统受到较大功率扰动时可以有效、迅速地转换控制方式,提升系统稳定性。
When multi-terminal HVDC system is used for long distance power transmission, DC line voltage drop and DC line power loss make significant impacts on the precision of voltage margin control, which makes the control of DC voltage unstable. Therefore, a precise voltage margin control method is proposed. In this paper a mathematical model in dq coordinate for VSC based multi-terminal DC power transmission system （ VSC-MTDC）. Then the value of voltage margin is calculated and revised in controller, with adequate consideration of the influence of line voltage drop and power loss on control reference value, based on power flow calculation for DC system. A simulation model of modular multilevel converter （ MMC ） based MTDC system in PSCAD/EMTDC is established to verify the correctness and validity of the proposed control method. The results show that with this method control characteristic deviations caused by unsuitable setting of voltage margin value could be avoided, and the control mode could be quickly switched under large power disturbance to improve the system stability.
出处
《电力建设》
2013年第4期1-7,共7页
Electric Power Construction
基金
国家自然科学基金项目(51177042)
国家高技术研究发展计划(863计划)项目(SS2013AA050105)
教育部中央高校基本科研业务费专项资金资助项目(12QX13)
