基于VSC-HVDC有功支援和自适应低频减载的区域电网频率控制

相比采用交流线路连接,当区域电网采用柔性直流输电(VSC-HVDC)连接时,主网不主动响应区域电网频率变化,降低了区域电网调频能力。提出基于VSC-HVDC有功支援和自适应低频减载的区域电网控制算法。当区域电网频率跌落时,利用增量法估计有功功率缺额。在保证主网频率安全的前提下,通过VSC-HVDC向区域电网提供有功支援。然后根据区域电网频率跌落幅度,确定是否进行低频减载,设计了自适应低频减载算法。仿真结果表明,所提出的频率控制算法能有效维持区域电网频率稳定,减少低频减载量。

Frequency control for regional system based on active power support from VSC-HVDC and adaptive under-frequency load shedding

When the regional power system is connected to main grid with the Voltage Source Converter based HVDC (VSC-HVDC), the main grid does not actively respond to frequency drop of the regional system; thus the regional system has less frequency control capability compared with that connected with AC line. Frequency control algorithm based on active power support from VSC-HVDC and adaptive under-frequency load shedding is proposed. With frequency drop in the regional system, the active power deficiency is estimated with the incremental method. With precondition of frequency security of the main grid, active power support is provided to the regional system by the VSC-HVDC. The adaptive under-frequency load shedding strategy is designed according to subsequent frequency drop. The numerical results show that the proposed algorithm effectively maintains frequency stability of the regional system and decreases load shedding.