大型交直流并联输电网网损优化理论及其在南方电网中的实现

Theoretical Study of Loss Minimization for a Large AC/DC Power System and Its Implementation in CSG Systems

交直流并联电网的网损优化问题与传统无功优化问题有很大不同,纯交流电网主要通过合理配置系统无功以降低网损,而交直流并联电网则是通过调整直流功率改变有功潮流分布,从而实现降低全网网损。尤其对于远距离、大容量、交直流并联送电的南方电网,调整交直流潮流分布降低主网网损则具有更加重要的意义。然而实际运行中主要依靠经验调整交直流潮流,亟需一种能够指导交直流输电网损优化的理论方法和适用于大规模系统的网损分析工具。该文系统分析交直流潮流分布影响网损的机理,提出相应网损优化最优潮流模型和最优等网损微增率原则。同时提出适用于大区电网规模的实用计算方法,在保留系统完整拓扑模型基础上实现算法的高准确性、稳定性和快速性。所提出的交直流并联电网网损分析理论和实用方法,已经应用于南方电网实际调度运行工作,并取得了较大的降损效益。

The loss minimization for AC/DC hybrid power grid is different from that of traditional AC power grid. For traditional AC power grid, the transmission loss is minimized by adjusting the distribution of reactive power in the system. For AC/DC hybrid power grid, the transmission loss can be minimized by adjusting DC power which can change the active power flow allocated between AC and DC transmission corridors, and this method is important for China Southern Power Grid （CSG） where the power transfer is huge through its AC/DC hybrid transmission network, since there are few theortical studies and practical method for the loss minimization of AC/DC power grid, the dispatcher of CSG can only adjust DC power by experience to reduce the transmission loss. This paper presents the theoretical analysis of the loss minimization for AC/DC system. The optimal power flow model to minimize the system loss by adjusting DC power is proposed. The optima criteria, which is equal loss sensitivity rule of such problem is proposed. The practical computation method for large scale system, such as CSG with more than 9 000 buses, is also provided is the paper. The realization of proposed method by this paper is introduced and the effect shows that the benefit of loss minization for CSG AC/DC hybrid grid is significant.