西南电力设计院，四川省 成都市 610021

金沙江一期3回特高压直流输电工程具有直流输送容量大、送端换流站群间距离近、交流电网联系紧密的特点。在金沙江一期的其中1回直流系统双极闭锁时，为减少金沙江送端切机数量和避免向交流通道大规模功率转移，作者提出了充分利用另2回直流系统的直流暂态和稳态过负荷能力相结合的协调功率调制策略，同时简单分析了多回直流间的协调控制以提高全系统稳定性的机理。仿真结果表明，该策略可改善金沙江一期送端交直流系统的稳定性，在1回直流故障双极闭锁后，金沙江一期水电站可不切或少切机。

The three circuit UHVDC power transmission of the first phase Jinsha River project possesses following features: high DC transmission capacity, short distances among converter stations at sending end and close connection with UHVAC power grid. When the bipolar shutting down occurs in one of DC circuit of the first phase Jinsha River project, in order to reduce the number of units to be cut off in Xiluodu/Xiangjiaba hydropower station and avoid large-scale power flow transferring to UHVAC transmission system, a coordinated power regulation strategy among the three UHVDC circuits is proposed, in which the DC transient and steady state overload capabilities of the other two UHVDC circuits are fully utilized, meanwhile the mechanism of coordinated control among multi-DC circuits to enhance the stability of whole system is simply analyzed. Simulation results show that the proposed strategy can improve the stability of UHVAC/UHVDC system at the sending end of the first phase Jinsha River project; when bipolar shutting down occurs in one UHVDC circuit due to fault, the number of cut-off units in hydropower stations of the first phase Jinsha River project can be reduced or the cut-off of unit can be avoided.