摘要
为了解决常规直流不能单独送风电的问题,分析了风电场孤岛直流外送系统的不稳定性机理,指出风电场不能与高压直流系统配合的原因在于"缺少不平衡功率自动消除机制",基于此提出一种解决方法,即在送端交流母线处附加VSC装置及其稳定控制策略,使送端电源整体接近电压源外特性并具备不平衡功率消除机制。一方面,VSC为DFIG提供了三相电压旋转矢量,保证DFIG的正常运行;另一方面,反馈VSC电容电压,根据电容电压的变化来反映直流送端系统频率变化,通过频率变化调节直流输送功率从而消除直流送端系统不平衡功率,实现了系统稳定运行的目标。基于所提出方法进行了实时数字仿真器(real time digital simulator,RTDS)的闭环验证,实验结果表明,此方法建立的不平衡功率消除机制,是解决风电场与传统直流单独配合问题的可行方法,且所需VSC装置容量仅为直流传输容量的1%左右。
To solve the problem that traditional DC system is not capable of transmitting electrical power alone, the in stability mechanism of HVDC transmission system for islanded wind farm is analyzed, and the lack of autosuppressing measures for unbalanced power is regarded as the reason of the incapability of cooperation between wind farm and HVDC. A solution is proposed to introduce an additional VSC with stability control strategy at the sending end of AC bus so the external characteristic of the sending end source performs similarly as a voltage source and the unbalanced power can be suppressed. On one hand, VSC provides threephase voltage rotating vector to maintain the regular operation of DFIG. On the other hand, the capacity voltage of VSC is fed back to monitor the frequency fluctuation at the sending end of HVDC and adjust the transmitted power to suppress the unbalanced power. Thus, the stable operation of the system is achieved. A closed loop is verified by real time digital simulator（RTDS） carried on, and the results indicate that the pro posed suppressing mechanism is a valid method for the cooperation of wind farm and traditional DC system, and the capacity of the introduced VSC is only about 1% of the DC transmission capacity.
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2016年第7期2193-2198,共6页
High Voltage Engineering
基金
国家自然科学基金(51467003)~~
