受端不同步系统交直流通道外送能力耦合特性分析

针对仿真中发现的电源中心交直流通道外送能力耦合的特点进行理论研究,研究对象是受端为非同步电网的交直流外送通道暂态功角稳定性.对交直流外送系统进行等值数学建模、直流系统故障进行简要讨论后,给出交直流外送系统的转子运动方程,并展开功角稳定性分析.在此基础上,对交直流通道外送能力的耦合特性进行推导发现:增加直流外送功率能够提高交直流通道总外送能力;增加交流通道外送能力须调减直流外送功率,同时交直流通道总外送能力下降,且交流通道外送能力提高量小于直流外送功率调减量.在实际电网的基础上进行算例分析,仿真结果验证了理论分析的正确性.最后,通过一个简化系统对所得结论的工程应用进行简要讨论,从而为实际运行与后续研究提供参考.

Analysis of maximum transmission capacity coupling characteristics between AC and DC lines connected to asynchronous receiving-end systems

According to the transmission capacity coupling characteristics between AC and DC lines connected from power source center to asynchronous systems found in simulation, the power-angle transient stability of AC and DC transmission channel with asynchronous receiving-end power grid is studied. The power-angle transient stability analysis is conducted based on the system equivalent model and the analysis of DC failures. Then, it is found that the total transmission capacity increases as the DC sending power increases according to the rigorous derivation. Additionally, to improve the maximum transmission capacity of AC lines, the DC sending power needs to be reduced, which could result in a reduction of total transmission capacity, and the delivery capacity improvement of AC channel is less than the reduction of DC delivery power. Case studies of a practical power grid verify the effectiveness of the proposed model. Finally, the application of the proposal is discussed through a simplified power system, which provides reference for practical operation and further academic research.