异步联网后西南电网安全稳定特性分析

Stability characteristics of southwest China power grid after asynchronous interconnection

针对渝鄂背靠背柔性直流工程投运后,与两华电网异步联网运行条件下的西南电网进行计算分析。研究了异步联网后西南电网小干扰稳定、功角稳定及频率稳定等稳定特性的变化情况。结果表明,渝鄂背靠背后,西南电网小干扰特性变化,尖山近区故障激发弱阻尼振荡成为限制水电通道送出能力的新制约因素。暂态功角稳定性有所提升,不再成为限制川电外送的主要制约因素。频率稳定问题突出,且存在严重的由于水电机组负阻尼效应导致的超低频振荡风险。最后,针对上述风险提出了相应的建议与措施。研究结论对西南电网异步联网后的安全稳定运行提供一定的技术参考。

Southwest China Power Grid which is un-synchronized intercolmection with Central-North China Power Grid is calculated and analyzed after the commissioning of back to back VSC-HVDC between Chongqing and Hubei power grid. The operation characteristic of Southwest China power grid after asynchronous interconnection is studied, including small signal stability, rotor angle stability, and frequency stability. Results show that with Chongqing and Hubei back to back commissioning small signal stability varies and the weekly damped oscillation excited by faults around Jianshan substation becomes to be new constraint of sending of hydropower. Transient rotor angle stability is improved and is no longer the main factor to restrict the power transmission. It should be noted that frequency stability problem is prominent, and there is a serious risk of ultra-low frequency oscillation due to the negative damping of hydro generators. Finally, corresponding suggestions and measures are put forward for the above risks. The study could be technical reference for the planning and operation of the Southwest Power Grid. This work is supported by Science and Technology Project of State Grid Corporation of China ＂Study on source-grid collaboration frequency control technology for large-scale energy bases with multi-DC and AC/DC transmission systems＂.