交直流并联电网中直流功率紧急控制影响及优化研究

直流功率紧急控制可以提高故障后系统的暂态稳定水平,广域测量系统(WAMS)的快速发展为实现大电网交直流协调控制提供了技术前提。基于扩展等面积准则(EEAC)介绍了直流功率紧急控制提高系统暂态稳定性的机理,针对交直流并联电网中直流功率紧急控制造成的送受端电网不平衡功率通过交流通道形成的反馈可能导致某些关键断面潮流加重、恶化系统失稳模式的问题,认为交流控制措施(切机、切负荷)和直流功率紧急控制措施存在协调的空间。为评价交直流协调控制效果,建立了交直流协调优化控制的数学模型,将该协调问题转换为以控制代价最小为目标的优化问题。通过实际系统的仿真算例验证了交直流协调优化的必要性。

Research on effects and optimization of emergency DC power control in AC/DC hybrid power grid

With the development of interconnected scale of power grid, the foundation to realize large scale resource optimization configuration is established, and power system stability problems become complicated. More comprehensive control measures for large scale power grid security and stability control will be supported by wide area measurement system (WAMS). The mechanism of power system transient stability improved by emergency DC power control (EDCPC) is introduced based on extended equal area criterion (EEAC) theory. In AC/DC parallel connection grid, the imbalanced power induced by EDCPC will cause an extra feedback which might make adverse effects on some unstable mode through AC transmission lines. As a result there exit coordinated space between EDCPC measures and AC control measures, such as generators tripping, load tripping and so on. To evaluate the effects of AC/DC coordination control, a coordinated and optimal mathematical model is built. It is necessary for AC/DC coordination control which is verified by simulation.