特高压直流对交直流并联电网安全稳定影响

以南方电网为例,应用PSS/E仿真软件探讨含有特高压直流的电网中交流和直流系统相互影响机理,以便揭示交直流并联运行电网失稳的可能性。分析表明,多馈入直流系统中,受端交流故障对直流运行状态的破坏程度远较送端交流故障严重,其对系统稳定的影响与直流功率恢复速度有关,若直流恢复速度较慢,有可能使受端交流故障成为系统输电能力的约束故障。大容量直流对系统稳定影响表现为输电能力更高,双极故障后的安稳措施代价更大。

Influence of UHVDC System on the Security and Stability of AC/DC Interconnected Power Grid

With CSG as an example, the interaction mechanism between AC and DC systems in a AC/DC interconnected power grid is discussed with PSS/E software to open out the possibility of the grid being in instability. Analysis shows that receiving-end AC fault damages the HVDC system operation much more than the sending-end AC fault in a multi-infeed HVDC system, and its damage extent depends on the power recovering rate of the HVDC system, and for a HVDC system with slow power recovering rate, the receiving-end AC fault will possibly become a critical one to restrict transmission capacities. The larger is the capacity of the HVDC system, the higher is the transmission capacities of the parallel grid, but more expensive cost of system stability control.