一种典型交直流电力系统中的次同步谐振/振荡问题分析及抑制

Analysis and Suppression of Sub-Synchronous Resonance/Oscillation in a Typical AC/DC Power System

为减少丰水期云南电网弃水电量,南方电网开展了云贵互联的可行性研究。本文结合上述研究需求,针对近区同时包含火电机组、固定串补、高压直流输电系统的交直流电网,开展了三者之间的次同步谐振/振荡(sub-synchronous resonance/oscillation,SSR/SSO)相互作用分析及抑制技术研究。首先,从理论上计算分析了火电机组轴系、固定串补、高压直流输电系统各自可能引发交流系统SSR/SSO的频率,综合得出了系统中可能存在的三类振荡模态及其主导来源,并通过EMTDC故障时域仿真,对比分析验证了上述结论的正确性;进一步,根据SSR/SSO振荡模态的特点及其分布,从直流附加控制的角度提出了直流次同步阻尼控制器(sub-synchronous damping controller,SSDC)的改进设计方法,并据此设计了新的直流SSDC,在EMTDC中的故障时域仿真证明了该方法是正确有效的。

To reduce the amount of discarded hydropower of Yunnan Power Grid during flood season,a feasibility study on interconnection between Yunnan Power Grid and Guizhou Power Grid is conducted by China Southern Power Grid.For the above research requirements,interaction analysis and suppression technology of sub-synchronous resonance/oscillation(SSR/SSO)in the AC-DC power grid with thermal power units,fixed series compensations and HVDC transmission system are carried out.Firstly,the frequencies of the SSR/SSO in AC system,which may be caused by the three types of above-mentioned equipment respectively,are theoretically calculated and analyzed,then the possible three types of SSR/SSO modes and their dominant sources are obtained comprehensively,which are verified through the EMTDC fault time domain simulation and comparative analysis.Further,from the perspective of HVDC additional control,an improved design method of DC sub-synchronous damping controller(SSDC)is proposed according to the characteristics and distribution of the SSR/SSO modes in the power grid.The results of the fault time domain simulation in EMTDC with a new SSDC designed using the above method prove the correctness and effectiveness of the method.